The malaria and typhoid fever burden in the slums of Kolkata, India: data from a prospective community-based study

Comparison of model predictions of typhoid conjugate vaccine public health impact and cost-effectiveness

Models are useful to inform policy decisions on typhoid conjugate vaccine (TCV) deployment in endemic settings. However, methodological choices can influence model-predicted outcomes. To provide robust estimates for the potential public health impact of TCVs that account for structural model differences, we compared four dynamic and one static mathematical model of typhoid transmission and vaccine impact. All models were fitted to a common dataset of age-specific typhoid fever cases in Kolkata, India. We evaluated three TCV strategies: no vaccination, routine vaccination at 9 months of age, and routine vaccination at 9 months with a one-time catch-up campaign (ages 9 months to 15 years). The primary outcome was the predicted percent reduction in symptomatic typhoid cases over 10 years after vaccine introduction. For three models with economic analyses (Models A-C), we also compared the incremental cost-effectiveness ratios (ICERs), calculated as the incremental cost (US$) per disability-adjusted life-year (DALY) averted. Routine vaccination was predicted to reduce symptomatic cases by 10-46 % over a 10-year time horizon under an optimistic scenario (95 % initial vaccine efficacy and 19-year mean duration of protection), and by 2-16 % under a pessimistic scenario (82 % initial efficacy and 6-year mean protection). Adding a catch-up campaign predicted a reduction in incidence of 36-90 % and 6-35 % in the optimistic and pessimistic scenarios, respectively. Vaccine impact was predicted to decrease as the relative contribution of chronic carriers to transmission increased. Models A-C all predicted routine vaccination with or without a catch-up campaign to be cost-effective compared to no vaccination, with ICERs varying from $95-789 per DALY averted; two models predicted the ICER of routine vaccination alone to be greater than with the addition of catch-up campaign. Despite differences in model-predicted vaccine impact and cost-effectiveness, routine vaccination plus a catch-up campaign is likely to be impactful and cost-effective in high incidence settings such as Kolkata.

Quantifying antibiotic use in typhoid fever in India: a cross-sectional analysis of private sector medical audit data, 2013-2015

OBJECTIVES

To estimate the antibiotic prescription rates for typhoid in India.

DESIGN

Cross-sectional study.

SETTING

Private sector primary care clinicians in India.

PARTICIPANTS

The data came from prescriptions of a panel of 4600 private sector primary care clinicians selected through a multistage stratified random sampling accounting for the region, specialty type and patient turnover. The data had 671 million prescriptions for antibiotics extracted from the IQVIA database for the years 2013, 2014 and 2015.

PRIMARY AND SECONDARY OUTCOME MEASURES

Mean annual antibiotic prescription rates; sex-specific and age-specific prescription rates; distribution of antibiotic class.

RESULTS

There were 8.98 million antibiotic prescriptions per year for typhoid, accounting for 714 prescriptions per 100 000 population. Children 10-19 years of age represented 18.6% of the total burden in the country in absolute numbers, 20-29 year age group had the highest age-specific rate, and males had a higher average rate (844/100 000) compared with females (627/100 000). Ten different antibiotics accounted for 72.4% of all prescriptions. Cefixime-ofloxacin combination was the preferred drug of choice for typhoid across all regions except the south. Combination antibiotics are the preferred choice of prescribers for adult patients, while cephalosporins are the preferred choice for children and young age. Quinolones were prescribed as monotherapy in 23.0% of cases.

CONCLUSIONS

Nationally representative private sector antibiotic prescription data during 2013-2015 indicate a higher disease burden of typhoid in India than previously estimated. The total prescription rate shows a declining trend. Young adult patients account for close to one-third of the cases and children less than 10 years account for more than a million cases annually.

Facility-based disease surveillance and Bayesian hierarchical modeling to estimate endemic typhoid fever incidence, Kilimanjaro Region, Tanzania, 2007–2018

Growing evidence suggests considerable variation in endemic typhoid fever incidence at some locations over time, yet few settings have multi-year incidence estimates to inform typhoid control measures. We sought to describe a decade of typhoid fever incidence in the Kilimanjaro Region of Tanzania. Cases of blood culture confirmed typhoid were identified among febrile patients at two sentinel hospitals during three study periods: 2007–08, 2011–14, and 2016–18. To account for under-ascertainment at sentinel facilities, we derived adjustment multipliers from healthcare utilization surveys done in the hospital catchment area. Incidence estimates and credible intervals (CrI) were derived using a Bayesian hierarchical incidence model that incorporated uncertainty of our observed typhoid fever prevalence, of healthcare seeking adjustment multipliers, and of blood culture diagnostic sensitivity. Among 3,556 total participants, 50 typhoid fever cases were identified. Of typhoid cases, 26 (52%) were male and the median (range) age was 22 (<1–60) years; 4 (8%) were aged <5 years and 10 (20%) were aged 5 to 14 years. Annual typhoid fever incidence was estimated as 61.5 (95% CrI 14.9–181.9), 6.5 (95% CrI 1.4–20.4), and 4.0 (95% CrI 0.6–13.9) per 100,000 persons in 2007–08, 2011–14, and 2016–18, respectively. There were no deaths among typhoid cases. We estimated moderate typhoid incidence (≥10 per 100 000) in 2007–08 and low (<10 per 100 000) incidence during later surveillance periods, but with overlapping credible intervals across study periods. Although consistent with falling typhoid incidence, we interpret this as showing substantial variation over the study periods. Given potential variation, multi-year surveillance may be warranted in locations making decisions about typhoid conjugate vaccine introduction and other control measures.

There is evidence that typhoid fever incidence may vary over time, but there are few longitudinal studies estimating incidence. This is especially true in Sub-Saharan Africa, where recent estimates show wide variation in incidence across different settings, but very limited longitudinal descriptions from those settings. Incidence estimates were generated using facility-based surveillance data from three study periods that was adjusted for health-seeking behavior established through healthcare utilization surveys performed in the catchment area. In addition to coupling facility-based surveillance data with healthcare utilization data, we utilized a Bayesian statistical methodology in order to estimate incidence and characterize uncertainty around the estimates. Our results demonstrate moderate typhoid incidence in 2007–08 and low incidence during 2012–14 and 2016–18, but with overlapping credible intervals across study periods. Our data are consistent with evidence that endemic typhoid may vary substantially over time. Given potential variation, multi-year surveillance may be warranted in locations making decisions about typhoid conjugate vaccine introduction and other control measures.

Epidemiology of Multidrug Resistance among Salmonella enterica serovars typhi and paratyphi A at a Tertiary Pediatric Hospital in India Over a Decade; In-silico Approach to Elucidate the Molecular Mechanism of Quinolone Resistance

BACKGROUND

Enteric fever caused by Salmonella enterica serovar typhi and Salmonella enterica serovar paratyphi A remains one of the most common causes of community-acquired bloodstream infection among children in India. Multidrug resistance is emerging and is a cause of concern as it affects the choice of treatment in enteric fever.

METHOD

In this study, a 10-year analysis of resistance patterns was done along with in-silico homology modeling and molecular docking to understand the commonly occurring quinolone resistance.

RESULTS

A total of 1010 cases of blood culture-confirmed enteric fevers (S. typhi n=849; S. paratyphi A n=161) were recorded at the study hospital during the period from 2011-2020. Multidrug resistance among cases of S. typhi was 2.12 %, whereas it was completely absent among cases of S. paratyphi A. Fluoroquinolone resistance was high (>95%) throughout the study period. Resistance to ampicillin, chloramphenicol and co-trimoxacole was low (<3%) among S. typhi cases. No deaths were observed among study participants. Molecular docking analysis showed that quinolone had less binding affinity to mutated gyrase A than to its wild type for both S. typhi and S. paratyphi A.

CONCLUSION

Quinolone resistance was high among cases of enteric fever, whereas no resistance was observed among third-generation cephalosporins. In-silico studies indicated that a mutation in gyrase A might be the cause of the gradual increase in ciprofloxacin resistance over the study period.

A contextual exploration of healthcare service use in urban slums in Nigeria

Introduction

Many urban residents in low- and middle-income countries live in unfavorable conditions with few healthcare facilities, calling to question the long-held view of urban advantage in health, healthcare access and utilization. We explore the patterns of healthcare utilization in these deprived neighborhoods by studying three such settlements in Nigeria.

Methods

The study was conducted in three slums in Southwestern Nigeria, categorized as migrant, indigenous or cosmopolitan, based on their characteristics. Using observational data of those who needed healthcare and used in-patient or out-patient services in the 12 months preceding the survey, frequencies, percentages and odds-ratios were used to show the study participants’ environmental and population characteristics, relative to their patterns of healthcare use.

Results

A total of 1,634 residents from the three slums participated, distributed as 763 (migrant), 459 (indigenous) and 412 (cosmopolitan). Residents from the migrant (OR = 0.70, 95%CI: 0.51 to 0.97) and indigenous (OR = 0.65, 95%CI: 0.45 to 0.93) slums were less likely to have used formal healthcare facilities than those from the cosmopolitan slum. Slum residents were more likely to use formal healthcare facilities for maternal and perinatal conditions, and generalized pains, than for communicable (OR = 0.50, 95%CI: 0.34 to 0.72) and non-communicable diseases (OR = 0.61, 95%CI: 0.41 to 0.91). The unemployed had higher odds (OR = 1.45, 95%CI: 1.08 to 1.93) of using formal healthcare facilities than those currently employed.

Conclusion

The cosmopolitan slum, situated in a major financial center and national economic hub, had a higher proportion of formal healthcare facility usage than the migrant and indigenous slums where about half of families were classified as poor. The urban advantage premise and Anderson behavioral model remain a practical explanatory framework, although they may not explain healthcare use in all possible slum types in Africa. A context-within-context approach is important for addressing healthcare utilization challenges in slums in sub-Saharan Africa.

Gender difference in the incidence of malaria diagnosed at public health facilities in Uganda

BACKGROUND

Routine malaria surveillance data in Africa primarily come from public health facilities reporting to national health management information systems. Although information on gender is routinely collected from patients presenting to these health facilities, stratification of malaria surveillance data by gender is rarely done. This study evaluated gender difference among patients diagnosed with parasitological confirmed malaria at public health facilities in Uganda.

METHODS

This study utilized individual level patient data collected from January 2020 through April 2021 at 12 public health facilities in Uganda and cross-sectional surveys conducted in target areas around these facilities in April 2021. Associations between gender and the incidence of malaria and non-malarial visits captured at the health facilities from patients residing within the target areas were estimated using poisson regression models controlling for seasonality. Associations between gender and data on health-seeking behaviour from the cross-sectional surveys were estimated using poisson regression models controlling for seasonality.

RESULTS

Overall, incidence of malaria diagnosed per 1000 person years was 735 among females and 449 among males (IRR = 1.72, 95% CI 1.68-1.77, p < 0.001), with larger differences among those 15-39 years (IRR = 2.46, 95% CI 2.34-2.58, p < 0.001) and over 39 years (IRR = 2.26, 95% CI 2.05-2.50, p < 0.001) compared to those under 15 years (IRR = 1.46, 95% CI 1.41-1.50, p < 0.001). Female gender was also associated with a higher incidence of visits where malaria was not suspected (IRR = 1.77, 95% CI 1.71-1.83, p < 0.001), with a similar pattern across age strata. These associations were consistent across the 12 individual health centres. From the cross-sectional surveys, females were more likely than males to report fever in the past 2 weeks and seek care at the local health centre (7.5% vs. 4.7%, p = 0.001) with these associations significant for those 15-39 years (RR = 2.49, 95% CI 1.17-5.31, p = 0.018) and over 39 years (RR = 2.56, 95% CI 1.00-6.54, p = 0.049).

CONCLUSIONS

Females disproportionately contribute to the burden of malaria diagnosed at public health facilities in Uganda, especially once they reach childbearing age. Contributing factors included more frequent visits to these facilities independent of malaria and a higher reported risk of seeking care at these facilities for febrile illnesses.

Factors Predicting Blood Culture Positivity in Children With Enteric Fever

BACKGROUND

Blood culture, despite low sensitivity, is the gold standard for enteric fever diagnosis. Understanding predictors of blood culture positivity may help design strategies to optimize enteric fever diagnosis.

METHODS

A cohort of 6760 children aged 0.5-15 years was followed for 3 years for enteric fever with blood cultures in an automated system, for fevers >3 days. Factors affecting test positivity in fevers and participant-level predictors for culture refusals were analyzed using regression models.

RESULTS

Overall, 6097 suspected typhoid/paratyphoid fever (STF) episodes were reported, of which 5703 (93.5%) STFs had sampling for blood cultures, with 394 (6.5%) refusals. Salmonella enterica serovar Typhi/Paratyphi positivity was culture-confirmed in 3.8% (218/5703) of STF episodes. Older children (odds ratio [OR], 1.96 [95% CI, 1.39-2.77]), larger blood volume inoculated (OR, 2.82 [95% CI, 1.71-4.66]), higher temperatures during fever (OR, 3.77 [95% CI, 2.89-4.91]), and fevers diagnosed as suspected typhoid or acute undifferentiated fever (OR, 6.06 [95% CI, 3.11-11.78]) had a higher probability of culture positivity. Antibiotics before culture did not decrease culture positivity. Blood culture refusals were higher for children from wealthier households or with milder illness.

CONCLUSIONS

Performing blood cultures in older children with fever, especially those fevers with toxic presentation and increasing blood volume for inoculation are strategies to improve enteric fever detection in surveillance settings.

Water, Sanitation, and Hygiene Practices in Urban Slums of Eastern India

Background

The Sustainable Development Goals identified universal access to water and sanitation facilities as key components for improving health. We assessed water, sanitation, and hygiene (WASH) practices and associated determinants among residents of urban slums in Kolkata, India.

Methods

Information on WASH practices was collected in 2 surveys (2018 and 2019) from participants of a prospective enteric fever surveillance conducted in 2 municipal wards of Kolkata. A composite WASH practice score was computed and a hierarchical stepwise multiple linear regression model constructed to identify key determinants of improved WASH score.

Results

Over 90% of households had access to piped water; 6% reported access to continuous supply. Adult women (61% in 2018; 45% in 2019) spent 20 minutes daily to fetch water. Access to improved latrines was almost universal, although 80% used shared facilities. Unhealthy disposal of children’s stools was reported in both rounds. Food hygiene practices were high, with most (>90%) washing uncooked items before eating; frequent consumption of street food items was reported.

Conclusions

The study area reported high WASH coverage. Unhygienic behavioral patterns predisposing to food- or water-borne diseases were also noted. Awareness building and sustainable community mobilization for food hygiene needs to be emphasized to ensure community well-being.

Prevalence, probability, and outcomes of typhoidal/non-typhoidal Salmonella and malaria co-infection among febrile patients: a systematic review and meta-analysis

The geographical overlaps of malaria parasites and Salmonella spp. can lead to co-infection of these two pathogens, especially in the tropics where malaria is endemic. Moreover, few literatures suggested that malaria infection was associated with Salmonella bacteremia. Therefore, this study quantified pooled prevalence of typhoidal/non-typhoidal Salmonella (NTS) and probability of typhoidal/NTS and malaria co-infection among febrile patients. The systematic review protocol was registered at PROSPERO (CRD42021252322). Studies on co-infection of typhoidal/NTS and malaria were searched in PubMed, Scopus, and Web of Science. The risk of bias of the included studies was assessed using the checklist for analytical cross-sectional studies developed by the Joanna Briggs Institute. Meta-analyses on the following criteria were performed: (1) pooled prevalence of typhoidal/NTS and malaria co-infection among febrile patients, (2) pooled prevalence of typhoidal/NTS among malaria patients, (3) pooled prevalence of malaria infections among patients with Salmonella spp. infection, and (4) probability of typhoidal/NTS and malaria co-infection among febrile patients. Additionally, the case fatality rate and mean difference of malarial parasitemia between typhoidal/NTS and malaria co-infection and Plasmodium monoinfection were also determined. The subgroup analyses of typhoidal/NTS, regions (Africa and Asia), countries, time (publication year), characteristics of participants, and diagnostic tests for identifying Salmonella spp. were also conducted. A sensitivity test was performed to determine the robustness of the study outcomes. Publication bias among the included studies was evaluated using the funnel plot and Egger’s test. All analyses were performed using Stata version 15 (StataCorp LLC, Texas, USA) with a p-value < 0.05 indicating statistical significance. Eighty-one studies that met the eligibility criteria were included in the analyses. Of the 73,775 study participants, 4523 had typhoidal/NTS and malaria co-infections. The pooled prevalence rates of typhoidal/NTS and malaria co-infection among febrile patients were 14% (95% confidence interval [CI], 9–19%; I², 99.4%; 2971/17,720 cases) and 1% (95% CI 1–1%; I², 89.9%; 252/29,081 cases) using the Widal test and culture methods for identifying Salmonella spp., respectively. The pooled prevalence rates of typhoidal/NTS infection among patients with malaria were 31% (95% CI 23–39%; I², 99.5%; 3202/19,208 cases) and 3% (95% CI 2–3%; I², 86.8%; 407/40,426 cases) using the Widal test and culture methods for identifying Salmonella spp., respectively. The pooled prevalence rates of malaria infection among patients with typhoidal/NTS were 17% (95% CI 6–29%; I², 33.3%; 13/75 cases) and 43% (95% CI 32–53%; I², 89.1%; 287/736 cases), respectively. Malaria infection was associated with typhoidal/NTS in children aged < 15 years (p < 0.0001; odds ratio, 0.36; 95% CI 0.23–0.58; I², 73.9%; 3188/43,212 cases). The case fatality rate in patients with malaria and NTS co-infections was 16% (95% CI 9–24%; I², 89.1%; 18/103 cases). From the view of the present study, the inappropriate use of the Widal test for Salmonella spp. diagnosis can overestimate the prevalence of typhoidal/NTS and malaria co-infections. Malaria infection associated with typhoidal/NTS in children and the high case fatality rates among few patients with co-infections were highlighted. Future prospective longitudinal studies using the appropriate and confirmatory dsiagnosis for Salmonella spp. infections are highly recommended to ensure the real prevalence of co-infection and highlight the outcome of co-infection for providing adequate treatment in febrile patients who live in areas where malaria is endemic, such as tropical Africa and India.

Trends of neglected Plasmodium species infection in humans over the past century in India

BACKGROUND

Efforts for malaria elimination in India focus solely on the more prevalent human malaria parasites of Plasmodium falciparum (Pf) and Plasmodium vivax (Pv). The three non-Pf/Pv species - Plasmodium malariae (Pm), Plasmodium ovale (Po) and Plasmodium knowlesi (Pk) are seldom studied though they are often present as mixed infections with Pf/Pv and thus may be misdiagnosed. This study provides a comprehensive landscape of Pm, Po, and Pk infections from 1930 to 2020.

METHODOLOGY

We systematically searched for published literature on Pm, Po, and Pk in India from PubMed database and collated data from 35 studies. The data, starting from 1930, were mapped decade-wise across India. The prevalence of the three neglected Plasmodium species and their proportional contribution to reported Plasmodium mixed-infection were also calculated and analysed.

PRINCIPAL FINDINGS

Amongst the three non-Pf/Pv species, Pm infections have been reported in greater numbers across India and were mostly mono-infections till 1980. From 1983 onwards, reports of Pm mixed infections with Pf/Pv started to emerge. In contrast, reports on occurrence of Po are still rare barring few mixed infection studies. Further, Pk mono- and mixed cases were first reported in 2004 in India and Pk now has been found reported from four Indian states.

CONCLUSION

This is the first account of country-wide assimilation of reported malaria parasite species data that covers Pm, Po, and Pk infection profiles from 1930 to 2020. This study illustrates the need to survey all 5 human malaria parasite species in India and to target them collectively during the malaria elimination phase.

Complications and mortality of typhoid fever: A global systematic review and meta-analysis

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Complications and death are considerable among hospitalized patients with typhoid fever.

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Case fatality ratio of typhoid fever was higher in Africa compared to Asia.

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Among studies in Africa, 20% of patients with typhoid intestinal perforation died.

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Delays in care were correlated with increased typhoid case fatality ratio in Asia.

Objectives

Updated estimates of the prevalence of complications and case fatality ratio (CFR) among typhoid fever patients are needed to understand disease burden.

Methods

Articles published in PubMed and Web of Science from 1 January 1980 through 29 January 2020 were systematically reviewed for hospital or community-based non-surgical studies that used cultures of normally sterile sites, and hospital surgical studies of typhoid intestinal perforation (TIP) with intra- or post-operative findings suggestive of typhoid. Prevalence of 21 pre-selected recognized complications of typhoid fever, crude and median (interquartile range) CFR, and pooled CFR estimates using a random effects meta-analysis were calculated.

Results

Of 113 study sites, 106 (93.8%) were located in Asia and Africa, and 84 (74.3%) were non-surgical. Among non-surgical studies, 70 (83.3%) were hospital-based. Of 10,355 confirmed typhoid patients, 2,719 (26.3%) had complications. The pooled CFR estimate among non-surgical patients was 0.9% for the Asia region and 5.4% for the Africa region. Delay in care was significantly correlated with increased CFR in Asia (r = 0.84; p<0.01). Among surgical studies, the median CFR of TIP was 15.5% (6.7–24.1%) per study.

Conclusions

Our findings identify considerable typhoid-associated illness and death that could be averted with prevention measures, including typhoid conjugate vaccine introduction.

A micro-epidemiological report on the unstable transmission of malaria in Aligarh, India

India contributes approximately 70% to the malaria burden of Southeast Asia. The transmission of disease in the country is generally hypoendemic, seasonal and unstable. Most researchers focus upon the hyperendemic malarious regions with stable malaria transmission. There is paucity of data regarding malaria transmission in hypoendemic regions, here we are presenting an epidemiological picture of clinical manifestations through a hospital-based survey in Aligarh, India, during 2016-18. Two thousand sixty-eight patients were diagnosed with malaria infection in Jawaharlal Nehru Medical College and Hospital (JNMCH), out of which 1104 were enrolled for clinical analysis. Ninety per cent of the cases were reported during July-November, and the rest in the dry season. A progressive increase in the prevalence rate was observed during the study period, i.e. 4.8, 7.57 and 8.7% in 2016, 2017 and 2018, respectively. Of the total cases, 75.77% had vivax malaria, while rest suffered from falciparum malaria. The risk of disease was significantly higher in the age group 0-15 years compared to all other age groups (p < .0001). The infection rate was higher in males (61%) compared to females (39%) p < .0001. Overall 8.6% of the patients had severe malaria who fulfilled the WHO criteria. The increasing rate of malaria infection during the study period and a considerable no. of severe vivax malaria cases warrant an efficient disease monitoring system, pointing towards the need to carry out micro-epidemiological studies in order to estimate the real burden of malaria in the country.

Ownership of Mother and Children's Health Book and Complete Basic Immunization Status in Slums and Poor Population

Background: The percentage of complete immunization in urban areas is higher than rural areas. The purpose of the study was to analyze the relationship between ownership of Maternal and Child Health (MCH) books with Complete Basic Immunization (CBI) coverage in slums and poor areas.

Design and Methods: A rapid survey was conducted in selected slums and poor groups based on medical records from Public Health Center. Informants were mothers with a sample of 325 infants aged 12 to 23 months.

Results: The lowest coverage of CBI for slum and poor residents is Pasuruan, which is 55.4%. The results of statistical analysis showed that there was a significant relationship between ownership of MCH books and the complete coverage of basic immunization in Malang (P = 0.000; PR = 3.682); Pasuruan (P = 0.002; PR = 1.854); Sidoarjo (P = 0.000; PR = 4.042); Surabaya (P = 0.000; PR = 2.425).

Conclusions: It is recommended that the government should improve access to complete immunization programs in slums and poor population.

Factors associated with occurrence of salmonellosis among children living in Mukuru slum, an urban informal settlement in Kenya

Background

In Kenya, typhoid fever and invasive non-typhoidal salmonellosis present a huge burden of disease, especially in poor-resource settings where clean water supply and sanitation conditions are inadequate. The epidemiology of both diseases is poorly understood in terms of severity and risk factors. The aim of the study was to determine the disease burden and spatial distribution of salmonellosis, as well as socioeconomic and environmental risk factors for these infections, in a large informal settlement near the city of Nairobi, from 2013 to 2017.

Methods

Initially, a house-to-house baseline census of 150,000 population in Mukuru informal settlement was carried out and relevant socioeconomic, demographic, and healthcare utilization information was collected using structured questionnaires. Salmonella bacteria were cultured from the blood and faeces of children < 16 years of age who reported at three outpatient facilities with fever alone or fever and diarrhea. Tests of association between specific Salmonella serotypes and risk factors were conducted using Pearson Chi-Square (χ²) test.

Results

A total of 16,236 children were recruited into the study. The prevalence of bloodstream infections by Non-Typhoidal Salmonella (NTS), consisting of Salmonella Typhimurium/ Enteriditis, was 1.3%; Salmonella Typhi was 1.4%, and this was highest among children < 16 years of age. Occurrence of Salmonella Typhimurium/ Enteriditis was not significantly associated with rearing any domestic animals. Rearing chicken was significantly associated with high prevalence of S. Typhi (2.1%; p = 0.011). The proportion of children infected with Salmonella Typhimurium/ Enteriditis was significantly higher in households that used water pots as water storage containers compared to using water directly from the tap (0.6%). Use of pit latrines and open defecation were significant risk factors for S. Typhi infection (1.6%; p = 0.048). The proportion of Salmonella Typhimurium/ Enteriditis among children eating street food 4 or more times per week was higher compared to 1 to 2 times/week on average (1.1%; p = 0.032).

Conclusion

Typhoidal and NTS are important causes of illness in children in Mukuru informal settlement, especially among children less than 16 years of age. Improving Water, Sanitation and Hygiene (WASH) including boiling water, breastfeeding, hand washing practices, and avoiding animal contact in domestic settings could contribute to reducing the risk of transmission of Salmonella disease from contaminated environments.

Typhoid fever: Control & challenges in India

Enteric fever is a common but serious disease that affects mostly children and adolescents in the developing countries. Salmonella enterica serovar Typhi remains responsible for most of the disease episodes; however, S. Paratyphi A has also been reported as an emerging infectious agent of concern. The control measures for the disease must encompass early diagnosis, surveillance and vaccine to protect against the disease. Sanitation and hygiene play a major role in reducing the burden of enteric diseases as well. The current status of diagnostics, the surveillance practices in the recent past and the vaccine development efforts have been taken into account for suggesting effective prevention and control measures. However, the challenges in all these aspects persist and cause hindrance in the implementation of the available tools. Hence, an integrative approach and a comprehensive policy framework are required to be in place for the prevention, control and elimination of typhoid fevers.

Designing a typhoid environmental surveillance study: A simulation model for optimum sampling site allocation

Environmental surveillance can be used for monitoring enteric disease in a population by detecting pathogens, shed by infected people, in sewage. Detection of pathogens depends on many factors: infection rates and shedding in the population, pathogen fate in the sewerage network, and also sampling sites, sample size, and assay sensitivity. This complexity makes the design of sampling strategies challenging, which creates a need for mathematical modeling to guide decision making.

In the present study, a model was developed to simulate pathogen shedding, pathogen transport and fate in the sewerage network, sewage sampling, and detection of the pathogen. The simulation study used Salmonella enterica serovar Typhi (S. Typhi) as the target pathogen and two wards in Kolkata, India as the study area. Five different sampling strategies were evaluated for their sensitivity of detecting S. Typhi, by sampling unit: sewage pumping station, shared toilet, adjacent multiple shared toilets (primary sampling unit), pumping station + shared toilets, pumping station + primary sampling units. Sampling strategies were studied in eight scenarios with different geographic clustering of risk, pathogen loss (decay, leakage), and sensitivity of detection assays. A novel adaptive sampling site allocation method was designed, that updates the locations of sampling sites based on their performance. We then demonstrated how the simulation model can be used to predict the performance of environmental surveillance and how it is improved by optimizing the allocation of sampling sites.

The results are summarized as a decision tree to guide the sampling strategy based on disease incidence, geographic distribution of risk, pathogen loss, and the sensitivity of the detection assay. The adaptive sampling site allocation method consistently outperformed alternatives with fixed site locations in most scenarios. In some cases, the optimum allocation method increased the median sensitivity from 45% to 90% within 20 updates.

Comparison of anti-Vi IgG responses between two clinical studies of typhoid Vi conjugate vaccines (Vi-DT vs Vi-TT)

Salmonella enterica serovar Typhi (S. Typhi) is a causative agent for typhoid fever and especially critical in developing countries. Although clinical studies for various typhoid conjugate vaccines (TCVs) have been performed, there are no comparative data on the immune responses of vaccines due to lack of harmonization of the serological assay. Recently, Typbar-TCV (Vi-TT) was prequalified by WHO and recommended for vaccination in endemic areas. Forty-eight serum samples were selected from a recent Vi-DT phase 1 study based on age cohort and anti-Vi IgG levels using an in-house ELISA. Anti-Vi IgG titers of 48 sera were also determined by Vacczyme ELISA, used in a Vi-TT phase 3 trial. A good correlation between the two assays was observed when the anti-Vi IgG titer was determined using Vacczyme ELISA based on the Vi-IgG_R1,2011, U.S. reference reagent (Pearson correlation coefficient (r) = 0.991, P < 0.001) or Vacczyme ELISA calibrator (r = 0.991, P < 0.001). Based on the correlation, multiple linear regression model was developed to convert data of 281 sera (prior to vaccination and 28 days post first-dose) in the Vi-DT phase 1 study from in-house ELISA titers to Vacczyme ELISA values and then, compared with the Vi-TT results. Similar estimates of anti-Vi IgG GMT were observed after vaccination with the Vi-DT and Vi-TT vaccines [1626 EU/ml (95% CI: 1292–2047) vs 1293 EU/ml (95% CI: 1153–1449), respectively]. The method used here can be implemented to estimate and compare anti-Vi IgG levels between different clinical studies of TCVs. This approach enables comparison of the antibody responses among TCVs under development and may help facilitate licensing of new TCVs.

Typhoid fever is an infectious and life-threatening disease in developing countries. Before 2017, Ty21a and Vi polysaccharide vaccines were licensed but these are not recommended in young children under 2-year-old. Vaccine manufacturers are developing typhoid Vi conjugate vaccines (TCVs) to improve immunogenicity. Typbar-TCV (Vi-TT) demonstrated its safety and immunogenicity in infants and recently, prequalified by WHO. Serum Vi-specific IgG antibody has been used to measure the immunogenicity of TCV in many clinical trials. However, due to lack of harmonized assay, comparison of the immunogenicity among various TCVs is not possible in the absence of head-to-head clinical trials. Recently, we evaluated immunogenicity of Vi-DT using an in-house ELISA in the clinical study. In this study, 48 sera were selected from Vi-DT phase 1 study and measured anti-Vi IgG using commercial Vacczyme ELISA kit, used in the phase 3 study of Vi-TT, to compare the immunogenicity between two vaccines. Based on the correlation between two assays, anti-Vi IgG of all participants in the Vi-DT study was converted to Vacczyme antibody value using statistical model and compared with results of Vi-TT phase 3 study. The antibody levels induced by two studies were similar in pre- and post-vaccinated sera. This approach enables to compare the antibody responses among TCVs under development and would facilitate licensing of new TCVs.

Prevalence of Neglected Tropical Diseases (Leishmaniasis and Lymphatic Filariasis) and Malaria Among a Migrant Labour Settlement in Kerala, India

Neglected tropical diseases (visceral leismaniasis, lymphatic filariasis) and malaria are endemic in northern states of India. Kerala has become a hub of construction activities employing a large number of migrants from these endemic states. Studies on morbidity pattern among migrants in Kerala are lacking. It is essential to look into the burden of these infections among migrant laborers who can act as reservoirs and are a threat to native population. A cross sectional study was done among migrant laborers in Ernakulam district, Kerala. After getting informed consent, a questionnaire was administered to each participant to collect sociodemographic details and 5 ml of blood was collected for detection of antigens using rapid diagnostic tests (RDT). Of the 309 migrants tested, none of them were positive for leishmaniasis, while 3.8% were positive for malaria and 3.6% for filariasis. With 2.5 million migrant laborers in Kerala, the magnitude of the problem in absolute numbers is enormous. Active surveillance and treatment is needed to prevent the reemergence of these diseases in Kerala.

A Retrospective Review of Hospital-Based Data on Enteric Fever in India, 2014-2015

Background

Enteric fever remains a threat to many countries with minimal access to clean water and poor sanitation infrastructure. As part of a multisite surveillance study, we conducted a retrospective review of records in 5 hospitals across India to gather evidence on the burden of enteric fever.

Methods

We examined hospital records (laboratory and surgical registers) from 5 hospitals across India for laboratory-confirmed Salmonella Typhi or Salmonella Paratyphi cases and intestinal perforations from 2014–2015. Clinical data were obtained where available. For laboratory-confirmed infections, we compared differences in disease burden, age, sex, clinical presentation, and antimicrobial resistance.

Results

Of 267536 blood cultures, 1418 (0.53%) were positive for S. Typhi or S. Paratyphi. Clinical data were available for 429 cases (72%); a higher proportion of participants with S. Typhi infection were hospitalized, compared with those with S. Paratyphi infection (44% vs 35%). We observed resistance to quinolones among 82% of isolates, with cases of cephalosporin resistance (1%) and macrolide resistance (9%) detected. Of 94 participants with intestinal perforations, 16 (17%) had a provisional, final, or laboratory-confirmed diagnosis of enteric fever.

Discussion

Data show a moderate burden of enteric fever in India. Enteric fever data should be systematically collected to facilitate evidence-based decision-making by countries for typhoid conjugate vaccines.

Global Typhoid Fever Incidence: A Systematic Review and Meta-analysis

BACKGROUND

Contemporary incidence estimates of typhoid fever are needed to guide policy decisions and control measures and to improve future epidemiological studies.

METHODS

We systematically reviewed 3 databases (Ovid Medline, PubMed, and Scopus) without restriction on age, country, language, or time for studies reporting the incidence of blood culture-confirmed typhoid fever. Outbreak, travel-associated, and passive government surveillance reports were excluded. We performed a meta-analysis using a random-effects model to calculate estimates of pooled incidence, stratifying by studies that reported the incidence of typhoid fever and those that estimated incidence by using multipliers.

RESULTS

Thirty-three studies were included in the analysis. There were 26 study sites from 16 countries reporting typhoid cases from population-based incidence studies, and 17 sites in 9 countries used multipliers to account for underascertainment in sentinel surveillance data. We identified Africa and Asia as regions with studies showing high typhoid incidence while noting considerable variation of typhoid incidence in time and place, including in consecutive years at the same location. Overall, more recent studies reported lower typhoid incidence compared to years prior to 2000. We identified variation in the criteria for collecting a blood culture, and among multiplier studies we identified a lack of a standardization for the types of multipliers being used to estimate incidence.

CONCLUSIONS

Typhoid fever incidence remains high at many sites. Additional and more accurate typhoid incidence studies are needed to support country decisions about typhoid conjugate vaccine adoption. Standardization of multiplier types applied in multiplier studies is recommended.

The Relationship Between Blood Sample Volume and Diagnostic Sensitivity of Blood Culture for Typhoid and Paratyphoid Fever: A Systematic Review and Meta-Analysis

Background

Blood culture is the standard diagnostic method for typhoid and paratyphoid (enteric) fever in surveillance studies and clinical trials, but sensitivity is widely acknowledged to be suboptimal. We conducted a systematic review and meta-analysis to examine sources of heterogeneity across studies and quantified the effect of blood volume.

Methods

We searched the literature to identify all studies that performed blood culture alongside bone marrow culture (a gold standard) to detect cases of enteric fever. We performed a meta-regression analysis to quantify the relationship between blood sample volume and diagnostic sensitivity. Furthermore, we evaluated the impact of patient age, antimicrobial use, and symptom duration on sensitivity.

Results

We estimated blood culture diagnostic sensitivity was 0.59 (95% confidence interval [CI], 0.54-0.64) with significant between-study heterogeneity (I2, 76% [95% CI, 68%-82%]; P < .01). Sensitivity ranged from 0.51 (95% CI, 0.44-0.57) for a 2-mL blood specimen to 0.65 (95% CI, 0.58-0.70) for a 10-mL blood specimen, indicative of a relationship between specimen volume and sensitivity. Subgroup analysis showed significant heterogeneity by patient age and a weak trend towards higher sensitivity among more recent studies. Sensitivity was 34% lower (95% CI, 4%-54%) among patients with prior antimicrobial use and 31% lower after the first week of symptoms (95% CI, 19%-41%). There was no evidence of confounding by patient age, antimicrobial use, symptom duration, or study date on the relationship between specimen volume and sensitivity.

Conclusions

The relationship between the blood sample volume and culture sensitivity should be accounted for in incidence and next-generation diagnostic studies.

Changing trends of culture-positive typhoid fever and antimicrobial susceptibility in a tertiary care North Indian Hospital over the last decade

Purpose

The present study was undertaken to analyse the trend in prevalence of culture-positive typhoid fever during the last decade and to determine antimicrobial susceptibility profile of Salmonella Typhi and Salmonella Paratyphi A isolated from patients of enteric fever presenting to our hospital.

Methods

All the culture-positive enteric fever cases during 2005-2016 presenting to our Hospital were included in the study. Antimicrobial susceptibility was done against chloramphenicol, amoxicillin, co-trimoxazole, ciprofloxacin, ofloxacin, levofloxacin, pefloxacin, ceftriaxone and azithromycin as per corresponding CLSI guidelines for each year. We also analysed the proportion of culture positivity during 1993-2016 in light of the antibiotic consumption data from published literature.

Results

A total of 1066 strains-S. Typhi (772) and S. Paratyphi A (294) were isolated from the blood cultures during the study. A maximum number of cases were found in July-September. Antimicrobial susceptibility for chloramphenicol, amoxicillin and co-trimoxazole was found to be 87.9%, 75.5%, 87.3% for S. Typhi and 94.2%, 90.1% and 94.2% for S. Paratyphi A, respectively. Ciprofloxacin, ofloxacin and levofloxacin susceptibility were 71.3%, 70.8% and 70.9% for S. Typhi and 58.1%, 57.4% and 57.1% for S. Paratyphi A, respectively. Azithromycin susceptibility was 98.9% in S. Typhi. Although susceptibility to ceftriaxone and cefixime was 100% in our isolates, there is a continuous increase in ceftriaxone minimum inhibitory concentration (MIC)₅₀and MIC₉₀values over the time. The proportion of blood culture-positive cases during 1993-2016 ranged from a minimum of 0.0006 in 2014 to a maximum of 0.0087 in 1999.

Conclusion

We found that the most common etiological agent of enteric fever is S. Typhi causing the majority of cases from July to October in our region. MIC to ceftriaxone in typhoidal salmonellae is creeping towards resistance and more data are needed to understand the azithromycin susceptibility.

Identification of priority health conditions for field-based screening in urban slums in Bangalore, India

BACKGROUND

Urban slums are characterised by unique challenging living conditions, which increase their inhabitants' vulnerability to specific health conditions. The identification and prioritization of the key health issues occurring in these settings is essential for the development of programmes that aim to enhance the health of local slum communities effectively. As such, the present study sought to identify and prioritise the key health issues occurring in urban slums, with a focus on the perceptions of health professionals and community workers, in the rapidly growing city of Bangalore, India.

METHODS

The study followed a two-phased mixed methods design. During Phase I of the study, a total of 60 health conditions belonging to four major categories: - 1) non-communicable diseases; 2) infectious diseases; 3) maternal and women's reproductive health; and 4) child health - were identified through a systematic literature review and semi-structured interviews conducted with health professionals and other relevant stakeholders with experience working with urban slum communities in Bangalore. In Phase II, the health issues were prioritised based on four criteria through a consensus workshop conducted in Bangalore.

RESULTS

The top health issues prioritized during the workshop were: diabetes and hypertension (non-communicable diseases category), dengue fever (infectious diseases category), malnutrition and anaemia (child health, and maternal and women's reproductive health categories). Diarrhoea was also selected as a top priority in children. These health issues were in line with national and international reports that listed them as top causes of mortality and major contributors to the burden of diseases in India.

CONCLUSIONS

The results of this study will be used to inform the development of technologies and the design of interventions to improve the health outcomes of local communities. Identification of priority health issues in the slums of other regions of India, and in other low and lower middle-income countries, is recommended.

INCIDENCE OF MALARIA/TYPHOID CO-INFECTION AMONG ADULT POPULATION IN UNWANA COMMUNITY, AFIKPO NORTH LOCAL GOVERNMENT AREA, EBONYI STATE, SOUTHEASTERN NIGERIA

BACKGROUND

Malaria and typhoid fever are two leading infections of poverty with serious health and socioeconomic impacts, and due to their geographical overlap, co-infections are very common. Their mimicking symptomatology often present with gross misdiagnosis and mistreatment. This study was carried out to determine the incidence of malaria and typhoid co-infections among adult population in Unwana Community, Afikpo-North Local Government Area of Ebonyi State.

MATERIALS AND METHODS

Three hundred and fifty (350) individuals were examined, their blood samples subjected to microscopic examination and widal agglutination tests, for identification of Plasmodium parasites and antibodies to Salmonella enterica serovar typhi respectively. Questionnaire was administered to obtain information on malaria/typhoid management practices.

RESULTS

Out of the 350 blood samples analysed, 190 (54.2%) were positive for malaria, 173 (49.4%) were positive for Salmonella enterica serovar typhi, while 127(36.2%) were positive for both typhoid and malaria. However, prevalence of malaria parasite was statistically significant in relation to sex (p<0.05), as males had 50% prevalence and females, 58%. For Salmonella enterica serovar typhi, the prevalence was not statistically significant in relation to sex (p>0.05); while males had 57% prevalence for Salmonella enteric serovar typhi, females had 42%. Sex was statistically significant (p<0.05) concerning prevalence rate of malaria/typhoid co-infection; males had 35% co-infection rate while females had 37%. The management practices studied revealed that over 80% of the respondents preferred environmental sanitation as the best prevention/control method. In the case of treatment, buying medicine from pharmacy shops was common (48%). This was followed by the use of herbal remedies (31%), while appreciable number adopted self-treatment method (18%).

CONCLUSION

Both malaria and typhoid were prevalent among the studied population with high rate of co-infection. Co-infection was higher in females than males and use of herbal medicine for treatment was common. Efforts should be made to improve on the living conditions of the people of Unwana and also, there should be public enlightenment on the preventive and control measures of the two diseases. Since both diseases have similar symptomatology, treatment should be based on adequate laboratory diagnosis. Also, personal hygiene is hereby encouraged among the populace.

Cost-effectiveness analysis of typhoid conjugate vaccines in five endemic low- and middle-income settings

BACKGROUND

Typhoid fever remains endemic in low- and middle-income countries. Programmatic use of existing vaccines is limited, but upcoming typhoid conjugate vaccines (TCVs) could warrant wider use. We evaluated the cost-effectiveness of five TCV delivery strategies in three urban areas (Delhi and Kolkata, India and Nairobi, Kenya) and two rural settings (Lwak, Kenya and Dong Thap, Vietnam) with varying incidence.

METHODS AND FINDINGS

We evaluated routine infant vaccination with and without catch-up campaigns among older individuals. We used a dynamic model of typhoid transmission to simulate cases, hospitalizations, deaths, disability-adjusted life-years (DALY) lost, treatment and intervention costs. We estimated cost-effectiveness (in terms of cost in international dollars (I$) per DALY averted) from the healthcare payer perspective, and assessed how it was influenced by uncertain model parameters. Compared to no vaccination, routine infant vaccination at I$1/dose was cost-saving in Delhi and Dong Thap, "very cost-effective" in Kolkata and Nairobi, and "cost-effective" in Lwak according to World Health Organization thresholds. However, routine vaccination was not the optimal strategy compared to strategies that included a catch-up campaign, which yielded the highest probability of being cost-saving in Delhi and Dong Thap and were most likely to provide a return on investment above a willingness-to-pay threshold of I$1440 in Kolkata, I$2300 in Nairobi, and I$5360 in Lwak. Vaccine price impacted the optimal strategy, and the number of doses required and rate of hospitalization were the primary sources of uncertainty.

CONCLUSION

Routine vaccination with TCV would be cost-effective in most settings, and additional one-time catch-up campaigns would also be economically justified.

Immunization, urbanization and slums - a systematic review of factors and interventions

Background

In 2014, over half (54%) of the world’s population lived in urban areas and this proportion will increase to 66% by 2050. This urbanizing trend has been accompanied by an increasing number of people living in urban poor communities and slums. Lower immunization coverage is found in poorer urban dwellers in many contexts. This study aims to identify factors associated with immunization coverage in poor urban areas and slums, and to identify interventions to improve coverage.

Methods

We conducted a systematic review, searching Medline, Embase, Global Health, CINAHL, Web of Science and The Cochrane Database with broad search terms for studies published between 2000 and 2016.

Results

Of 4872 unique articles, 327 abstracts were screened, leading to 63 included studies: 44 considering factors and 20 evaluating interventions (one in both categories) in 16 low or middle-income countries. A wide range of socio-economic characteristics were associated with coverage in different contexts. Recent rural-urban migration had a universally negative effect. Parents commonly reported lack of awareness of immunization importance and difficulty accessing services as reasons for under-immunization of their children. Physical distance to clinics and aspects of service quality also impacted uptake. We found evidence of effectiveness for interventions involving multiple components, especially if they have been designed with community involvement. Outreach programmes were effective where physical distance was identified as a barrier. Some evidence was found for the effective use of SMS (text) messaging services, community-based education programmes and financial incentives, which warrant further evaluation. No interventions were identified that provided services to migrants from rural areas.

Conclusion

Different factors affect immunization coverage in different urban poor and slum contexts. Immunization services should be designed in collaboration with slum-dwelling communities, considering the local context. Interventions should be designed and tested to increase immunization in migrants from rural areas.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-017-4473-7) contains supplementary material, which is available to authorized users.

The burden of typhoid fever in low- and middle-income countries: A meta-regression approach

Background

Upcoming vaccination efforts against typhoid fever require an assessment of the baseline burden of disease in countries at risk. There are no typhoid incidence data from most low- and middle-income countries (LMICs), so model-based estimates offer insights for decision-makers in the absence of readily available data.

Methods

We developed a mixed-effects model fit to data from 32 population-based studies of typhoid incidence in 22 locations in 14 countries. We tested the contribution of economic and environmental indices for predicting typhoid incidence using a stochastic search variable selection algorithm. We performed out-of-sample validation to assess the predictive performance of the model.

Results

We estimated that 17.8 million cases of typhoid fever occur each year in LMICs (95% credible interval: 6.9–48.4 million). Central Africa was predicted to experience the highest incidence of typhoid, followed by select countries in Central, South, and Southeast Asia. Incidence typically peaked in the 2–4 year old age group. Models incorporating widely available economic and environmental indicators were found to describe incidence better than null models.

Conclusions

Recent estimates of typhoid burden may under-estimate the number of cases and magnitude of uncertainty in typhoid incidence. Our analysis permits prediction of overall as well as age-specific incidence of typhoid fever in LMICs, and incorporates uncertainty around the model structure and estimates of the predictors. Future studies are needed to further validate and refine model predictions and better understand year-to-year variation in cases.

Typhoid fever is a bacterial enteric infection that continues to pose a considerable burden to the 5.5 billion people living in low- and middle-income countries (LMICs). We developed and validated a model incorporating widely available indicators of economic and social development and the environment to estimate the burden of typhoid fever across LMICs. Our analysis uses all available data to estimate the incidence of typhoid in key age groups, which is important for the design and implementation of optimal vaccination strategies, and it identifies regions of the world that have the most uncertainty in typhoid incidence. Across all LMICs, we estimated that the expected number of typhoid fever cases per year is 17.8 million (95% CI: 6.9–48.4 million). We also present the probability that incidence surpasses the criteria for low, medium, high, and very high incidence in each country, which could help guide policy in the face of uncertainty.

Whole Genome Sequence Analysis of Salmonella Typhi Isolated in Thailand before and after the Introduction of a National Immunization Program

Vaccines against Salmonella Typhi, the causative agent of typhoid fever, are commonly used by travellers, however, there are few examples of national immunization programs in endemic areas. There is therefore a paucity of data on the impact of typhoid immunization programs on localised populations of S. Typhi. Here we have used whole genome sequencing (WGS) to characterise 44 historical bacterial isolates collected before and after a national typhoid immunization program that was implemented in Thailand in 1977 in response to a large outbreak; the program was highly effective in reducing typhoid case numbers. Thai isolates were highly diverse, including 10 distinct phylogenetic lineages or genotypes. Novel prophage and plasmids were also detected, including examples that were previously only reported in Shigella sonnei and Escherichia coli. The majority of S. Typhi genotypes observed prior to the immunization program were not observed following it. Post-vaccine era isolates were more closely related to S. Typhi isolated from neighbouring countries than to earlier Thai isolates, providing no evidence for the local persistence of endemic S. Typhi following the national immunization program. Rather, later cases of typhoid appeared to be caused by the occasional importation of common genotypes from neighbouring Vietnam, Laos, and Cambodia. These data show the value of WGS in understanding the impacts of vaccination on pathogen populations and provide support for the proposal that large-scale typhoid immunization programs in endemic areas could result in lasting local disease elimination, although larger prospective studies are needed to test this directly.

Typhoid fever is a systemic infection caused by the bacterium Salmonella Typhi. Typhoid fever is associated with inadequate hygiene in low-income settings and a lack of sanitation infrastructure. A sustained outbreak of typhoid fever occurred in Thailand in the 1970s, which peaked in 1975–1976. In response to this typhoid fever outbreak the government of Thailand initiated an immunization program, which resulted in a dramatic reduction in the number of typhoid cases in Thailand. To better understand the population of S. Typhi circulating in Thailand at this time, as well as the impact of the immunization program on the pathogen population, we sequenced the genomes of 44 S. Typhi obtained from hospitals in Thailand before and after the immunization program. The genome sequences showed that isolates of S. Typhi bacteria isolated from post-immunization era typhoid cases were likely imported from neighbouring countries, rather than strains that have persisted in Thailand throughout the immunization period. Our work provides the first historical insights into S. Typhi in Thailand during the 1970s, and provides a model for the impact of immunization on S. Typhi populations.

Antimicrobial resistance and molecular subtypes of Salmonella enterica serovar Typhi isolates from Kolkata, India over a 15 years period 1998-2012

Typhoid fever, caused by Salmonella enterica serovar Typhi (S. Typhi), remains an unresolved public health problem in India. Emergence of antimicrobial resistant strains poses a great concern for typhoid treatment and influences reshaping of current S. Typhi population. We included representative S. Typhi strains (n=164) from retrospective studies, both community and hospital based, conducted at National Institute of Cholera and Enteric Diseases, Kolkata during 15 years period (1998-2012) to analyze their antimicrobial resistance (AMR) profiles, mechanism of AMR and molecular subtypes of the strains. More than 60% of the S. Typhi isolates were obtained from community based studies. During the study period, steady decline (46.4%-15.6%) in isolation of multidrug-resistant (MDR, resistant to ampicillin, chloramphenicol and co-trimoxazole) S. Typhi was noticed with parallel increase of nalidixic acid-resistant (NAL^R) strains (60.7%-93.8%) and ciprofloxacin resistant (CIP^R) strains (0%-25%). Of 53 MDR strains, 46 (86.8%) were NAL^R showing decreased ciprofloxacin susceptible (DCS) (MIC for ciprofloxacin 0.12-0.5μg/ml) phenotype. Conjugative IncHI1 (230kb) and non-conjugative non-IncHI1 (180kb) plasmids were found in 23 (43.4%) and 14 (26.4%) MDR strains respectively, plasmid was absent in 16 (30.2%) MDR strains. MDR strains with or without plasmid shared the same set of resistance genes (bla_TEM-1, catA1, sul1, sul2, strA and strB) and class 1 integron possessing dfrA7 gene cassette. Two S. Typhi strains harbored 50kb transferrable plasmids carrying dfrA15 and aadA1 gene cassettes in class 1 integron. The majority of the strains (135/164, 82.3%) belonged to H58 haplotype. Among the MDR isolates, fluoroquinolone resistant or combined resistant isolates (n=147), 127 (86.4%) were H58 and 20 (13.6%) belonged to non-H58. NAL^RS. Typhi strains with decreased susceptibility or resistance to ciprofloxacin had point mutation(s) in quinolone resistance-determining region of gyrA and parC genes. Pulsed-field gel electrophoresis showed more diversity among NAL^RS. Typhi than MDR strains. Results of this study generated information useful for better understanding of the disease epidemiology and its control in endemic settings.

Estimating the spatial distribution of acute undifferentiated fever (AUF) and associated risk factors using emergency call data in India. A symptom-based approach for public health surveillance

The System for Early-warning based on Emergency Data (SEED) is a pilot project to evaluate the use of emergency call data with the main complaint acute undifferentiated fever (AUF) for syndromic surveillance in India. While spatio-temporal methods provide signals to detect potential disease outbreaks, additional information about socio-ecological exposure factors and the main population at risk is necessary for evidence-based public health interventions and future preparedness strategies. The goal of this study is to investigate whether a spatial epidemiological analysis at the ecological level provides information on urban-rural inequalities, socio-ecological exposure factors and the main population at risk for AUF. Our results displayed higher risks in rural areas with strong local variation. Household industries and proximity to forests were the main socio-ecological exposure factors and scheduled tribes were the main population at risk for AUF. These results provide additional information for syndromic surveillance and could be used for evidence-based public health interventions and future preparedness strategies.

Plasmodium falciparum malaria and invasive bacterial co-infection in young African children: the dysfunctional spleen hypothesis

Children with recent or acute malaria episodes are at increased risk of invasive bacterial infections (IBI). However, the exact nature of the malaria-IBI association is still unclear. Young children have an age-related spleen immunologic immaturity, mainly due to the still ongoing development of the marginal zone (MZ) B cell subset. By mounting a rapid antibody response against encapsulated bacteria, these cells are critical for the defence against highly pathogenic microorganisms that do not elicit classical T cell-dependent responses. There is increasing evidence that the anatomy of the spleen becomes disorganized during malaria infection, with complete dissolution of the MZ and apoptosis of MZ B cells. Correspondingly, a reduction in the frequency of the peripheral equivalent of the MZ B cells has been found in malaria endemic areas. A remarkable similarity exists in IBI susceptibility between African children with malaria and hyposplenic or splenectomized patients. However, studies specifically assessing the immune function of the spleen in controlling bacterial infections in young children with malaria are scarce.

Here, it is hypothesized that Plasmodium falciparum malaria infection constitutes a detrimental factor in the still immature spleen function of young children, resulting in a factually hyposplenic state during malaria episodes, putting children with malaria at a high risk to develop life-threatening bacterial infections. Studies to confirm or reject this hypothesis are greatly needed, as well as the development of affordable and feasible tools to assess the immune spleen function against encapsulated bacteria in children with malaria.

Stochastic simulation of endemic Salmonella enterica serovar Typhi: the importance of long lasting immunity and the carrier state

Background

Typhoid fever caused by Salmonella enterica serovar Typhi (S. Typhi) remains a serious burden of disease, especially in developing countries of Asia and Africa. It is estimated that it causes 200,000 deaths per year, mainly in children. S. Typhi is an obligate pathogen of humans and although it has a relatively complex life cycle with a long lived carrier state, the absence of non-human hosts suggests that well targeted control methods should have a major impact on disease. Newer control methods including new generations of vaccines offer hope but their implementation would benefit from quantitative models to guide the most cost effective strategies. This paper presents a quantitative model of Typhoid disease, immunity and transmission as a first step in that process.

Methodology/Principal Findings

A stochastic agent-based model has been developed that incorporates known features of the biology of typhoid including probability of infection, the consequences of infection, treatment options, acquisition and loss of immunity as a result of infection and vaccination, the development of the carrier state and the impact of environmental or behavioral factors on transmission. The model has been parameterized with values derived where possible from the literature and where this was not possible, feasible parameters space has been determined by sensitivity analyses, fitting the simulations to age distribution of field data. The model is able to adequately predict the age distribution of typhoid in two settings.

Conclusions/Significance

The modeling highlights the importance of variations in the exposure/resistance of infants and young children to infection in different settings, especially as this impacts on design of control programs; it predicts that naturally induced clinical and sterile immunity to typhoid is long lived and highlights the importance of the carrier state especially in areas of low transmission.

Vivax malaria and bacteraemia: a prospective study in Kolkata, India

BACKGROUND

Falciparum malaria increases the risk for bacteraemia, whereas the relationship between vivax malaria and bacteraemia is not clear. Data from a prospective fever surveillance study in Kolkata, India were reanalysed for the potential association between Plasmodium vivax malaria and bacteraemia.

METHODS

Patients of all ages presenting with fever of three days or more to a project health outpost were invited to participate. A blood film and blood culture was performed on presentation. Treatment and referral were provided according to national guidelines. The case fraction and incidence of malaria, bacteraemia, and co-infection were calculated.

RESULTS

3,371 participants were enrolled during a one-year study period, of whom 93/3,371 (2.8%) had malaria (89/93 [95.7%] Plasmodium vivax) and 256 (7.6%) bacteraemia. There were 154 malaria, 423 bacteraemia and 10 P. vivax-bacteremia coinfection episodes per 100,000/year. Among the malaria-bacteraemia co-infections, all were vivax malaria and 5/6 (83%) bacteria isolated were Gram-negative (one S. Typhi, one S. Paratyphi A, three other Gram-negative). Bacteraemia occurred in 6/89 (6.7% [95%CI: 3.1-13.9%]) of P. vivax cases versus 250/3,278 (7.6% [95% CI: 6.7-8.6%]) without Plasmodium infection (p=0.76).

CONCLUSIONS

While an increased risk was not demonstrated, concomitant bacteraemia occurs frequently in vivax malaria in an area with a high background incidence of bacteraemia, and should be considered in cases of vivax malaria with severe manifestations.

A ubiquitous method for street scale spatial data collection and analysis in challenging urban environments: mapping health risks using spatial video in Haiti

BACKGROUND

Fine-scale and longitudinal geospatial analysis of health risks in challenging urban areas is often limited by the lack of other spatial layers even if case data are available. Underlying population counts, residential context, and associated causative factors such as standing water or trash locations are often missing unless collected through logistically difficult, and often expensive, surveys. The lack of spatial context also hinders the interpretation of results and designing intervention strategies structured around analytical insights. This paper offers a ubiquitous spatial data collection approach using a spatial video that can be used to improve analysis and involve participatory collaborations. A case study will be used to illustrate this approach with three health risks mapped at the street scale for a coastal community in Haiti.

METHODS

Spatial video was used to collect street and building scale information, including standing water, trash accumulation, presence of dogs, cohort specific population characteristics, and other cultural phenomena. These data were digitized into Google Earth and then coded and analyzed in a GIS using kernel density and spatial filtering approaches. The concentrations of these risks around area schools which are sometimes sources of diarrheal disease infection because of the high concentration of children and variable sanitary practices will show the utility of the method. In addition schools offer potential locations for cholera education interventions.

RESULTS

Previously unavailable fine scale health risk data vary in concentration across the town, with some schools being proximate to greater concentrations of the mapped risks. The spatial video is also used to validate coded data and location specific risks within these "hotspots".

CONCLUSIONS

Spatial video is a tool that can be used in any environment to improve local area health analysis and intervention. The process is rapid and can be repeated in study sites through time to track spatio-temporal dynamics of the communities. Its simplicity should also be used to encourage local participatory collaborations.

Plasmodium vivax: clinical spectrum, risk factors and pathogenesis

Vivax malaria was historically described as 'benign tertian malaria' because individual clinical episodes were less likely to cause severe illness than Plasmodium falciparum. Despite this, Plasmodium vivax was, and remains, responsible for major morbidity and significant mortality in vivax-endemic areas. Single infections causing febrile illness in otherwise healthy individuals rarely progress to severe disease. Nevertheless, in the presence of co-morbidities, P. vivax can cause severe illness and fatal outcomes. Recurrent or chronic infections in endemic areas can cause severe anaemia and malnutrition, particularly in early childhood. Other severe manifestations include acute lung injury, acute kidney injury and uncommonly, coma. Multiorgan failure and shock are described but further studies are needed to investigate the role of bacterial and other co-infections in these syndromes. In pregnancy, P. vivax infection can cause maternal anaemia, miscarriage, low birth weight and congenital malaria. Compared to P. falciparum, P. vivax has a greater capacity to elicit an inflammatory response, resulting in a lower pyrogenic threshold. Conversely, cytoadherence of P. vivax to endothelial cells is less frequent and parasite sequestration is not thought to be a significant cause of severe illness in vivax malaria. With a predilection for young red cells, P. vivax does not result in the high parasite biomass associated with severe disease in P. falciparum, but a four to fivefold greater removal of uninfected red cells from the circulation relative to P. falciparum is associated with a similar risk of severe anaemia. Mechanisms underlying the pathogenesis of severe vivax syndromes remain incompletely understood.

Urban inequities; urban rights: a conceptual analysis and review of impacts on children, and policies to address them

This paper explores current conceptual understanding of urban social, environmental, and health inequality and inequity, and looks at the impact of these processes on urban children and young people in the 21st century. This conceptual analysis was commissioned for a discussion paper for UNICEF's flagship publication: State of the World's Children 2012: Children in an Urban World. The aim of the paper is to examine evidence on the meaning of urban inequality and inequity for urban children and young people. It further looks at the controversial policies of targeting "vulnerable" young people, and policies to achieve the urban MDGs. Finally, the paper looks briefly at the potential of concepts such as environment justice and rights to change our understanding of urban inequality and inequity.

Age-dependent sex bias in clinical malarial disease in hypoendemic regions

BACKGROUND AND OBJECTIVES

Experimental models show a male bias in murine malaria; however, extant literature on biases in human clinical malaria is inconclusive. Studies in hyperendemic areas document an absence of sexual dimorphism in clinical malaria. Data on sex bias in clinical malaria in hypoendemic areas is ambiguous--some reports note a male bias but do not investigate the role of differential mosquito exposure in that bias. Moreover, these studies do not examine whether the bias is age related. This study investigates whether clinical malaria in hypoendemic regions exhibits a sex bias and whether this bias is age-dependent. We also consider the role of vector exposure in this bias.

METHODS

Retrospective passive clinical malaria datasets (2002-2007) and active surveillance datasets (2000-2009) were captured for the hypoendemic Mumbai region in Western India. To validate findings, passive retrospective data was captured from a primary malaria clinic (2006-2007) in hypoendemic Rourkela (Eastern India). Data was normalized by determining percent slide-positivity rates (SPRs) for males and females, and parasite-positivity distributions were established across age groups. The Mann-Whitney test, Wilcoxon Signed Rank test, and Chi-square analysis were used to determine statistical significances.

RESULTS

In both the Mumbai and Rourkela regions, clinical malaria exhibited an adult male bias (p<0.01). A sex bias was not observed in children aged ≤10. Post-puberty, male SPRs were significantly greater than females SPRs (p<0.01). This adult male bias was observed for both vivax and falciparum clinical disease. Analysis of active surveillance data did not reveal an age or sex bias in the frequency of parasite positivity.

CONCLUSION

This study demonstrates an age-dependent sex bias in clinical malaria in hypoendemic regions and enhanced incidence of clinical malaria in males following puberty. Possible roles of sex hormones, vector exposure, co-infections, and other factors in this enhanced susceptibility are discussed.

High-resolution genotyping of the endemic Salmonella Typhi population during a Vi (typhoid) vaccination trial in Kolkata

BACKGROUND

Typhoid fever, caused by Salmonella enterica serovar Typhi (S. Typhi), is a major health problem especially in developing countries. Vaccines against typhoid are commonly used by travelers but less so by residents of endemic areas.

METHODOLOGY

We used single nucleotide polymorphism (SNP) typing to investigate the population structure of 372 S. Typhi isolated during a typhoid disease burden study and Vi vaccine trial in Kolkata, India. Approximately sixty thousand people were enrolled for fever surveillance for 19 months prior to, and 24 months following, Vi vaccination of one third of the study population (May 2003-December 2006, vaccinations given December 2004).

PRINCIPAL FINDINGS

A diverse S. Typhi population was detected, including 21 haplotypes. The most common were of the H58 haplogroup (69%), which included all multidrug resistant isolates (defined as resistance to chloramphenicol, ampicillin and co-trimoxazole). Quinolone resistance was particularly high among H58-G isolates (97% Nalidixic acid resistant, 30% with reduced susceptibility to ciprofloxacin). Multiple typhoid fever episodes were detected in 22 households, however household clustering was not associated with specific S. Typhi haplotypes.

CONCLUSIONS

Typhoid fever in Kolkata is caused by a diverse population of S. Typhi, however H58 haplotypes dominate and are associated with multidrug and quinolone resistance. Vi vaccination did not obviously impact on the haplotype population structure of the S. Typhi circulating during the study period.

Fluoroquinolones for treating typhoid and paratyphoid fever (enteric fever)

BACKGROUND

Typhoid and paratyphoid are febrile illnesses, due to a bacterial infection, which remain common in many low- and middle-income countries. The World Health Organization (WHO) currently recommends the fluoroquinolone antibiotics in areas with known resistance to the older first-line antibiotics.

OBJECTIVES

To evaluate fluoroquinolone antibiotics for treating children and adults with enteric fever.

SEARCH STRATEGY

We searched The Cochrane Infectious Disease Group Specialized Register (February 2011); Cochrane Central Register of Controlled Trials (CENTRAL), published in The Cochrane Library (2011, Issue 2); MEDLINE (1966 to February 2011); EMBASE (1974 to February 2011); and LILACS (1982 to February 2011). We also searched the metaRegister of Controlled Trials (mRCT) in February 2011.

SELECTION CRITERIA

Randomized controlled trials examining fluoroquinolone antibiotics, in people with blood, stool or bone marrow culture-confirmed enteric fever.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the trial's methodological quality and extracted data. We calculated risk ratios (RR) for dichotomous data and mean difference for continuous data with 95% confidence intervals (CI).Comparative effectiveness has been interpreted in the context of; length of treatment, dose, year of study, known levels of antibiotic resistance, or proxy measures of resistance such as the failure rate in the comparator arm.

MAIN RESULTS

Twenty-six studies, involving 3033 patients, are included in this review.Fluoroquinolones versus older antibiotics (chloramphenicol, co-trimoxazole, amoxicillin and ampicillin)In one study from Pakistan in 2003-04, high clinical failure rates were seen with both chloramphenicol and co-trimoxazole, although resistance was not confirmed microbiologically. A seven-day course of either ciprofloxacin or ofloxacin were found to be superior. Older studies of these comparisons failed to show a difference (six trials, 361 participants).In small studies conducted almost two decades ago, the fluoroquinolones were demonstrated to have fewer clinical failures than ampicillin and amoxicillin (two trials, 90 participants, RR 0.11, 95% CI 0.02 to 0.57).Fluoroquinolones versus current second-line options (ceftriaxone, cefalexin, and azithromycin)The two studies comparing a seven day course of oral fluoroquinolones with three days of intravenous ceftriaxone were too small to detect important differences between antibiotics should they exist (two trials, 89 participants).In Pakistan in 2003-04, no clinical or microbiological failures were seen with seven days of either ciprofloxacin, ofloxacin or cefixime (one trial, 139 participants). In Nepal in 2005, gatifloxacin reduced clinical failure and relapse compared to cefixime, despite a high prevalence of NaR in the study population (one trial, 158 participants, RR 0.04, 95% CI 0.01 to 0.31).Compared to a seven day course of azithromycin, a seven day course of ofloxacin had a higher rate of clinical failures in populations with both multi-drug resistance (MDR) and nalidixic acid resistance (NaR) enteric fever in Vietnam in 1998-2002 (two trials, 213 participants, RR 2.20, 95% CI 1.23 to 3.94). However, a more recent study from Vietnam in 2004-05, detected no difference between gatifloxacin and azithromycin with both drugs performing well (one trial, 287 participants).

AUTHORS' CONCLUSIONS

Generally, fluoroquinolones performed well in treating typhoid, and maybe superior to alternatives in some settings. However, we were unable to draw firm general conclusions on comparative contemporary effectiveness given that resistance changes over time, and many studies were small. Policy makers and clinicians need to consider local resistance patterns in choosing a fluoroquinolone or alternative.There is some evidence that the newest fluoroquinolone, gatifloxacin, remains effective in some regions where resistance to older fluoroquinolones has developed. However, the different fluoroquinolones have not been compared directly in trials in these settings.

Inactivation and sub-lethal injury of salmonella typhi, salmonella typhimurium and vibrio cholerae in copper water storage vessels

Background

This study provides information on the antibacterial effect of copper against the water-borne pathogens Salmonella Typhi, Salmonella Typhimurium and Vibrio cholerae.

Methods

Suspensions of each pathogen were kept in water within a traditional copper vessel at 30°C for 24 h. Samples were withdrawn, diluted and plated onto suitable growth media. Conventional enumeration of healthy (uninjured) bacteria was carried out using standard aerobic incubation conditions. Additionally, reactive oxygen species-neutralised (ROS-n) conditions were achieved by adding the peroxide scavenger sodium pyruvate to the medium with anaerobic incubation, to enumerate uninjured (ROS-insensitive) and injured (ROS-sensitive) bacteria. Differences between log-transformed means of conventional (aerobic) and ROS-n counts were statistically evaluated using t tests.

Results

Overall, all three pathogens were inactivated by storage in copper vessels for 24 h. However, for shorter-term incubation (4-12 h), higher counts were observed under ROS-n conditions than under aerobic conditions, which demonstrate the presence of substantial numbers of sub-lethally injured cells prior to their complete inactivation.

Conclusions

The present study has for the first time confirmed that these bacterial pathogens are inactivated by storage in a copper vessel within 24 h. However, it has also demonstrated that it is necessary to account for short-term sub-lethal injury, manifest as ROS-sensitivity, in order to more fully understand the process. This has important practical implications in terms of the time required to store water within a copper vessel to completely inactivate these bacteria and thereby remove the risk of water-borne disease transmission by this route.

Use of verbal autopsy to determine mortality patterns in an urban slum in Kolkata, India

OBJECTIVE

To define mortality patterns in an urban slum in Kolkata, India, in the context of a cholera and typhoid fever project.

METHODS

In a well-defined population that was under surveillance for 18 months, we followed a dynamic cohort of 63 788 residents whose households were visited monthly by community health workers to identify deaths. Trained physicians performed verbal autopsies and experienced senior physicians assigned the primary cause of death according to the International classification of diseases, 10th edition. We tabulated causes of death in accordance with Global Burden of Disease 2000 categories and assessed overall and cause-specific mortality rates per age group and gender.

FINDINGS

During 87 921 person-years of follow-up, we recorded 544 deaths. This gave an overall mortality rate of 6.2 per 1000 person-years. We assigned a cause to 89% (482/544) of the deaths. The leading causes of death, in descending order, were cardiovascular diseases (especially among adults aged over 40 years), cancer, respiratory ailments and digestive disorders. Most deaths in children under 5 years of age were caused by tuberculosis, respiratory infections and diarrhoeal diseases.

CONCLUSION

Although the most common causes of death in children were infectious, non-communicable diseases were predominant among adults. There is a need for continuing interventions against infectious diseases in addition to new and innovative strategies to combat non-infectious conditions.

A comparison of fluoroquinolones versus other antibiotics for treating enteric fever: meta-analysis

OBJECTIVES

To review evidence supporting use of fluoroquinolones as first line agents over other antibiotics for treating typhoid and paratyphoid fever (enteric fever).

DESIGN

Meta-analysis of randomised controlled trials.

DATA SOURCES

Cochrane Infectious Diseases Group specialised register, CENTRAL (issue 4, 2007), Medline (1966-2007), Embase (1974-2007), LILACS (1982-2007), selected conferences, reference lists, and ongoing trial register (November 2007). Review methods Trials comparing fluoroquinolones with chloramphenicol, cephalosporins, or azithromycin in culture-proven enteric fever were included. Two reviewers extracted data and assessed methodological quality. Odds ratios with 95% confidence intervals were estimated. Trials recruiting over 60% children were analysed separately from trials on adults. Primary outcomes studied were clinical failure, microbiological failure, and relapse.

RESULTS

Twenty trials were included. Trials were small and often of limited methodological quality. Only 10 trials concealed allocation and only three were blinded. In trials on adults, fluoroquinolones were not significantly different from chloramphenicol for clinical failure (594 participants) or microbiological failure (n=378), but reduced clinical relapse (odds ratio 0.14 (95% confidence interval 0.04 to 0.50), n=467, 6 trials). Azithromycin and fluoroquinolones were comparable (n=152, 2 trials). Compared with ceftriaxone, fluoroquinolones reduced clinical failure (0.08 (0.01 to 0.45), n=120, 3 trials) but not microbiological failure or relapse. Compared with cefixime, fluoroquinolones reduced clinical failure (0.05 (0.01 to 0.24), n=238, 2 trials) and relapse (0.18 (0.03 to 0.91), n=218, 2 trials). In trials on children infected with nalidixic acid resistant strains, older fluoroquinolones (ofloxacin) produced more clinical failures than azithromycin (2.67 (1.16 to 6.11), n=125, 1 trial), but there were no differences with newer fluoroquinolones (gatifloxacin, n=285, 1 trial). Fluoroquinolones and cefixime were not significantly different (n=82, 1 trial).

CONCLUSIONS

In adults, fluoroquinolones may be better than chloramphenicol for preventing clinical relapse. Data were limited for other comparisons, particularly for children.

Risk factors for typhoid in Darjeeling, West Bengal, India: evidence for practical action

OBJECTIVE

To identify risk factors for typhoid and propose prevention measures.

METHODS

Case-control study; we compared hospital-based typhoid cases defined as fever>38 degrees C for >or=3 days with four-fold rise in 'O' antibodies on paired sera (Widal) with community, age and neighbourhood matched controls. We obtained information on drinking water, fruits, vegetables, milk products and sanitation; and calculated matched odds ratios (MOR) and attributable fractions in the population (AFP) for the risk factors or failure to use prevention measures.

RESULTS

The 123 typhoid cases (median age: 25 years, 47% female) and 123 controls did not differ with respect to baseline characteristics. Cases were less likely to store drinking water in narrow-mouthed containers (MOR: 0.4, 95% CI: 0.2-0.7, AFP 29%), tip containers to draw water (MOR: 0.4, 95% CI: 0.2-0.7, AFP 33%) and have home latrines (MOR: 0.5, 95% CI: 0.3-0.8, AFP 23%). Cases were more likely to consume butter (OR: 2.3, 95% CI: 1.3-4.1, AFP 28%), yoghurt (OR: 2.3, 95% CI: 1.4-3.7, AFP 34%) and raw fruits and vegetables, including onions (MOR: 2.1, 95% CI: 1.2-3.9, AFP 34%), cabbages (OR: 2.8, 95% CI: 1.7-4.8, AFP 44%) and unwashed guavas (OR: 1.9, 95% CI: 1.2-3, AFP 25%).

CONCLUSION

Typhoid was associated with unsafe water and sanitation practices as well as with consumption of milk products, fruits and vegetables. We propose to chlorinate drinking water at the point of use, wash/cook raw fruits and vegetables and ensure safer preparation/storage of local milk products.

Fluoroquinolones for treating typhoid and paratyphoid fever (enteric fever)

BACKGROUND

Fluoroquinolones are recommended as first-line therapy for typhoid and paratyphoid fever (enteric fever), but how they compare with other antibiotics and different fluoroquinolones is unclear.

OBJECTIVES

To evaluate fluoroquinolone antibiotics for treating enteric fever in children and adults compared with other antibiotics, different fluoroquinolones, and different durations of fluoroquinolone treatment.

SEARCH STRATEGY

In November 2007, we searched the Cochrane Infectious Diseases Group Specialized Register, CENTRAL (The Cochrane Library 2007, Issue 4), MEDLINE, EMBASE, LILACS, mRCT, conference proceedings, and reference lists.

SELECTION CRITERIA

Randomized controlled trials of fluoroquinolones in people with blood or bone marrow culture-confirmed enteric fever.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the trials' methodological quality and extracted data. We calculated odds ratios (OR) for dichotomous data with 95% confidence intervals (CI). We analysed trials with greater than 60% children separately from trials of mostly adults.

MAIN RESULTS

Of 38 included trials, 22 had unclear allocation concealment and 34 did not use blinding. Four trials included exclusively children, seven had both adults and children, and three studied outpatients.

ADULTS

Among primary outcomes (clinical failure, microbiological failure, and relapse), compared with chloramphenicol, fluoroquinolones were not statistically significantly different for clinical failure (594 participants) or microbiological failure (378 participants), but they reduced clinical relapse (OR 0.14, 95% CI 0.04 to 0.50; 467 participants, 6 trials). We detected no statistically significant difference versus co-trimoxazole (82 participants, 2 trials) or azithromycin (152 participants, 2 trials). Fluoroquinolones reduced clinical failure compared with ceftriaxone (OR 0.08, 95% CI 0.01 to 0.45; 120 participants, 3 trials), but not microbiological failure or relapse. Versus cefixime, fluoroquinolones reduced clinical failure (OR 0.05, 95% CI 0.01 to 0.24; 238 participants; 2 trials) and relapse (OR 0.18, 95% CI 0.03 to 0.91; 218 participants, 2 trials).

CHILDREN

In children with high proportions of nalidixic acid-resistant strains, older fluoroquinolones increased clinical failures compared with azithromycin (OR 2.67, 95% CI 1.16 to 6.11; 125 participants, 1 trial), with no differences using newer fluoroquinolones (285 participants, 1 trial). Fluoroquinolones and cefixime were not statistically significantly different (82 participants, 1 trial). Trials comparing different durations of fluoroquinolone treatment were not statistically significantly different (889 participants, 9 trials). Norfloxacin had more clinical failures than other fluoroquinolones (417 participants, 5 trials).

AUTHORS' CONCLUSIONS

Trials were small and methodological quality varied. In adults, fluoroquinolones may be better for reducing clinical relapse rates compared to chloramphenicol. Data are limited for other comparisons, particularly in children.

Typhoid fever in children in Africa

Estimates for the year 2000 suggested that there were approximately 21.5 million infections and 200,000 deaths from typhoid fever globally each year, making the disease one of the most serious infectious disease threats to public health on a global scale. However, these estimates were based on little data, especially from Africa. Global prominence and high-profile outbreaks have created the perception in Kenya that typhoid is a common cause of febrile illness. The Widal test is used widely in diagnosis. We have reviewed recent literature, taking the perspective of a healthcare provider, to collate information on the prevalence of typhoid in children particularly, and to explore the role of clinical diagnosis and diagnosis based on a crude, but common, interpretation of the Widal test. Data suggest that typhoid in children in rural Africa is uncommon, perhaps 100 times or 250 times less common than invasive disease because of Haemophilus influenzae or Streptococcus pneumoniae, respectively. Frequent use of the Widal test may result in many hundreds of over-treatment episodes for every true case treated and may perpetuate the perception that typhoid is common. Countries such as Kenya need better bacterial disease surveillance systems allied to better information for healthcare providers to promote appropriate decision-making on prevention and treatment strategies.