Cholera in Africa: new momentum in fighting an old problem

Global oral cholera vaccine use, 2013-2018

Vaccination is a key intervention to prevent and control cholera in conjunction with water, sanitation and hygiene activities. An oral cholera vaccine (OCV) stockpile was established by the World Health Organization (WHO) in 2013. We reviewed its use from July 2013 to all of 2018 in order to assess its role in cholera control. We computed information related to OCV deployments and campaigns conducted including setting, target population, timelines, delivery strategy, reported adverse events, coverage achieved, and costs. In 2013-2018, a total of 83,509,941 OCV doses have been requested by 24 countries, of which 55,409,160 were approved and 36,066,010 eventually shipped in 83 deployments, resulting in 104 vaccination campaigns in 22 countries. OCVs had in general high uptake (mean administrative coverage 1st dose campaign at 90.3%; 2nd dose campaign at 88.2%; mean survey-estimated two-dose coverage at 69.9%, at least one dose at 84.6%) No serious adverse events were reported. Campaigns were organized quickly (five days median duration). In emergency settings, the longest delay was from the occurrence of the emergency to requesting OCV (median: 26 days). The mean cost of administering one dose of vaccine was 2.98 USD. The OCV stockpile is an important public health resource. OCVs were generally well accepted by the population and their use demonstrated to be safe and feasible in all settings. OCV was an inexpensive intervention, although timing was a limiting factor for emergency use. The dynamic created by the establishment of the OCV stockpile has played a role in the increased use of the vaccine by setting in motion a virtuous cycle by which better monitoring and evaluation leads to better campaign organization, better cholera control, and more requests being generated. Further work is needed to improve timeliness of response and contextualize strategies for OCV delivery in the various settings.

Concentration and sources of polycyclic aromatic hydrocarbons in some commercial herbal drugs used for cholera treatment in southwest Nigeria

The aim of this study was to investigate the cancer risk that could be incurred from the use of some anti-cholera herbal drugs sold in Southwest Nigeria. Three most popular anti-cholera herbal drugs were studied. The cancer risk estimation for the drugs at studied population ranges from 7.119 to 0.338 x 10-8 in children, 9.563 to 0.129 x 10-8 in preteen and 9.541 to 5.196 x 10-8 in adult. The cancer risk estimated values are below the USEPA set value 1 x 10-6. This established that the use of these herbal drugs might not lead to cancer if consumed at low dosage.

A cholera outbreak in a rural north central Nigerian community: an unmatched case-control study

Background

Cholera remains a disease of public health importance in Nigeria associated with high morbidity and mortality. In November 2014, the Nigeria Field Epidemiology and Laboratory Training Programme (NFELTP) was notified of an increase in suspected cholera cases in Gomani, Kwali Local Government Area. NFELTP residents were deployed to investigate the outbreak with the objectives of verifying the diagnosis, identifying risk factors and instituting appropriate control measures to control the outbreak.

Methods

We conducted an unmatched case-control study. We defined a cholera case as any person aged ≥5 years with acute watery diarrhea in Gomani community. We identified community controls. A total of 43 cases and 68 controls were recruited. Structured questionnaires were administered to both cases and controls. Four stool samples from case-patients and two water samples from the community water source were collected for laboratory investigation. We performed univariate and bivariate analysis using Epi-Info version 7.1.3.10.

Results

The mean age of cases and controls was 20.3 years and 25.4 respectively (p value 0.09). Females constituted 58.1% (cases) and 51.5%(controls). The attack rate was 4.3% with a case fatality rate of 13%. Four stool (100%) specimen tested positive for Vibrio cholerae. The water source and environment were polluted by indiscriminate defecation. Compared to controls, cases were more likely to have drank from Zamani river (OR 14.2, 95% CI: 5.5–36.8) and living in households(HH) with more than 5 persons/HH (OR 5.9, 95% CI: 1.3–27.2). Good hand hygiene was found to be protective (OR 0.3, 95% CI: 0.1–0.7).

Conclusion

Vibrio cholerae was the cause of the outbreak in Gomani. Drinking water from Zamani river, living in overcrowded HH and poor hand hygiene were significantly associated with the outbreak. We initiated hand hygiene and water treatment to control the outbreak.

Electronic supplementary material

The online version of this article (10.1186/s12889-018-6299-3) contains supplementary material, which is available to authorized users.

Feasibility, coverage and cost of oral cholera vaccination conducted by icddr,b using the existing national immunization service delivery mechanism in rural setting Keraniganj, Bangladesh

Background: Cholera is a considerable health burden in developing country settings including Bangladesh. The oral cholera vaccine (OCV) is a preventative tool to control the disease. The objective of this study was to describe whether the International Centre for Diarrheal Disease Research, Bangladesh (icddr,b), could provide the OCV to rural communities using existing government infrastructure.

Methods: The study was conducted in rural sub-district Keraniganj, 20 km from the capital city Dhaka. All listed participants one year and above in age (excluding pregnant women) were offered two doses of OCV at a 14 day interval. Existing government facilities were used to deliver and also maintain the cold chain required for the vaccine. All events related to vaccination were recorded at the 17 vaccination sites to evaluate the coverage and feasibility of OCV program.

Results: A total of 29,029 individuals received the 1st dose (90% of target) and 26,611 individuals received the 2nd dose (83% of target and 92% of 1st dose individuals) of OCV. The highest vaccination coverage was in younger children (1–9 years) and the lowest was amongst 18–29-year age group. Somewhat better coverage was seen amongst the female participants than males (92% vs. 88% for the 1st dose and 93% vs. 90% for the 2nd dose). The cost of vaccine cost was calculated as US$1.00 per dose plus freight, insurance, and transportation and the total vaccine delivery cost was US$70,957.

Conclusion: This was a project undertaken using existing public health program resources to collect empirical evidence on the use of a mass OCV campaign in the rural setting. Mass vaccination with the OCV is feasible in the rural setting using existing governmental vaccine delivery systems in Bangladesh.

Oral cholera vaccine coverage during a preventive door-to-door mass vaccination campaign in Nampula, Mozambique

Background

In addition to improving water, sanitation and hygiene (WASH) measures and optimal case management, the introduction of Oral cholera vaccine (OCV) is a complementary strategy for cholera prevention and control for vulnerable population groups. In October 2016, the Mozambique Ministry of Health implemented a mass vaccination campaign using a two-dose regimen of the Shanchol™ OCV in six high-risk neighborhoods of Nampula city, in Northern Mozambique. Overall 193,403 people were targeted by the campaign, which used a door-to-door strategy. During campaign follow-up, a population survey was conducted to assess: (1) OCV coverage; (2) frequency of adverse events following immunization; (3) vaccine acceptability and (4) reasons for non-vaccination.

Methodology/Principal findings

In the absence of a household listing and clear administrative neighborhood delimitations, we used geospatial technology to select households from satellite images and used the support of community leaders. One person per household was randomly selected for interview. In total, 636 individuals were enrolled in the survey. The overall vaccination coverage with at least one dose (including card and oral reporting) was 69.5% (95%CI: 51.2–88.2) and the two-dose coverage was 51.2% (95%CI: 37.9–64.3). The campaign was well accepted. Among the 185 non-vaccinated individuals, 83 (44.6%) did not take the vaccine because they were absent when the vaccination team visited their houses. Among the 451 vaccinated individuals, 47 (10%) reported minor and non-specific complaints, and 78 (17.3%) mentioned they did not receive any information before the campaign.

Conclusions/Significance

In spite of overall coverage being slightly lower than expected, the use of a mobile door-to-door strategy remains a viable option even in densely-populated urban settings. Our results suggest that campaigns can be successfully implemented and well accepted in Mozambique in non-emergency contexts in order to prevent cholera outbreaks. These findings are encouraging and complement the previous Mozambican experience related to OCV.

Antibiotics resistance in El Tor Vibrio cholerae 01 isolated during cholera outbreaks in Mozambique from 2012 to 2015

RATIONALE

Mozambique has recorded cyclically epidemic outbreaks of cholera. Antibiotic therapy is recommended in specific situations for management and control of cholera outbreaks. However, an increase in resistance rates to antibiotics by Vibrio cholerae has been reported in several epidemic outbreaks worldwide. On the other hand, there are few recent records of continuous surveillance of antibiotics susceptibility pattern of V. cholerae in Mozambique.

GOALS

The purpose of this study was to evaluate antibiotics resistance pattern of Vibrio cholerae O1 Ogawa isolated during Cholera outbreaks in Mozambique to commonly used antibiotics.

METHODOLOGY

We analyzed data from samples received in the context of surveillance and response to Cholera outbreaks in the National Reference Laboratory of Microbiology from the National Institute of Health of Mozambique, 159 samples suspected of cholera from cholera treatment centers of, Metangula (09), Memba (01), Tete City (08), Moatize (01), Morrumbala (01) districts, City of Quelimane (01), Lichinga (06) and Nampula (86) districts, from 2012 to 2015. Laboratory culture and standard biochemical tests were employed to isolate and identify Vibrio cholerae; serotypes were determined by antisera agglutination reaction in blade. Biotype and presence of important virulence factors analysis was done by PCR. Antibiotics susceptibility pattern was detected by disk diffusion method Kirby Bauer. Antibiotic susceptibility and results were interpreted by following as per recommendations of CLSI (Clinical and Laboratory Standards Institute) 2014. All samples were collected and tested in the context of Africhol Project, approved by the National Bioethics Committee for Health.

RESULTS

Among isolates from of Vibrio cholerae O1 El Tor Ogawa resistance to Sulphamethoxazole-trimethropim was 100% (53/53) to Trimethoprim-, being 100% (54/54) for Ampicillin, 99% (72/74) for Nalidixic Acid, 97% (64/66) to Chloramphenicol, 95% (42/44) for Nitrofurantoin and (19/20) Cotrimoxazole, 83% (80/97) Tetracycline, 56% (5/13) Doxycycline, 56% (39/70) Azithromycin and 0% (0/101) for Ciprofloxacin. PCR analysis suggested strains of V. cholerae O1 being descendants of the current seventh pandemic V. cholerae O1 CIRS 101 hybrid variant. The V. cholerae O1 currently causing cholera epidemics in north and central Mozambique confirmed a CTXΦ genotype and a molecular arrangement similar to the V. cholerae O1 CIRS 101.

CONCLUSION

Although V. cholerae infections in Mozambique are generally not treated with antibiotics circulating strains of the bacteria showed high frequency of in vitro resistance to available antibiotics. Continuous monitoring of antibiotic resistance pattern of epidemic strains is therefore crucial since the appearance of antibiotic resistance can influence cholera control strategies.

Epidemiology of cholera outbreaks and socio-economic characteristics of the communities in the fishing villages of Uganda: 2011-2015

Background

The communities in fishing villages in the Great Lakes Region of Africa and particularly in Uganda experience recurrent cholera outbreaks that lead to considerable mortality and morbidity. We evaluated cholera epidemiology and population characteristics in the fishing villages of Uganda to better target prevention and control interventions of cholera and contribute to its elimination from those communities.

Methodology/Principal findings

We conducted a prospective study between 2011–15 in fishing villages in Uganda. We collected, reviewed and documented epidemiological and socioeconomic data for 10 cholera outbreaks that occurred in fishing communities located along the African Great Lakes and River Nile in Uganda. These outbreaks caused 1,827 suspected cholera cases and 43 deaths, with a Case-Fatality Ratio (CFR) of 2.4%. Though the communities in the fishing villages make up only 5–10% of the Ugandan population, they bear the biggest burden of cholera contributing 58% and 55% of all reported cases and deaths in Uganda during the study period. The CFR was significantly higher among males than females (3.2% vs. 1.3%, p = 0.02). The outbreaks were seasonal with most cases occurring during the months of April-May. Male children under age of 5 years, and 5–9 years had increased risk. Cholera was endemic in some villages with well-defined “hotspots”. Practices predisposing communities to cholera outbreaks included: the use of contaminated lake water, poor sanitation and hygiene. Additional factors were: ignorance, illiteracy, and poverty.

Conclusions/Significance

Cholera outbreaks were a major cause of morbidity and mortality among the fishing communities in Uganda. In addition to improvements in water, sanitation, and hygiene, oral cholera vaccines could play an important role in the prevention and control of these outbreaks, particularly when targeted to high-risk areas and populations. Promotion and facilitation of access to social services including education and reduction in poverty should contribute to cholera prevention, control and elimination in these communities.

Cholera, though a preventable and treatable disease, remains a major cause of morbidity and mortality in the Great Lakes Region of Africa, including Uganda. The communities in the fishing villages constitute 5–10% of the total Ugandan population. Most fishing villages are located along Lakes Victoria, Albert and Edward and the River Nile. During the study period, 2011–2015 these villages were responsible for over 50% of the reported annual cholera cases and deaths in Uganda. The CFR was significantly higher among males than females (3.2% vs. 1.3%, p = 0.02). Our study is the first to systematically describe the epidemiology of these outbreaks and socioeconomic characteristics of communities in the fishing villages in Uganda. Our study found that persons in the fishing villages were at increased risk of cholera outbreaks due to poor access to safe water, sanitation, and hygiene. Furthermore, the villages had similar population characteristics such as illiteracy, ignorance regarding cholera transmission, poverty and constant population migration. In addition to improvements in water, sanitation, and hygiene, complementary use of oral cholera vaccines could play an important role, particularly when targeted to high-risk areas and populations. As a long term strategy, improvements in education and reduction in poverty should contribute to cholera prevention, control and elimination in the fishing villages and Uganda as whole.

Cross-Border Cholera Outbreaks in Sub-Saharan Africa, the Mystery behind the Silent Illness: What Needs to Be Done?

Introduction

Cross-border cholera outbreaks are a major public health problem in Sub-Saharan Africa contributing to the high annual reported cholera cases and deaths. These outbreaks affect all categories of people and are challenging to prevent and control. This article describes lessons learnt during the cross-border cholera outbreak control in Eastern and Southern Africa sub-regions using the case of Uganda-DRC and Malawi-Mozambique borders and makes recommendations for future outbreak prevention and control.

Materials and Methods

We reviewed weekly surveillance data, outbreak response reports and documented experiences on the management of the most recent cross-border cholera outbreaks in Eastern and Southern Africa sub-regions, namely in Uganda and Malawi respectively. Uganda-Democratic Republic of Congo and Malawi-Mozambique borders were selected because the countries sharing these borders reported high cholera disease burden to WHO.

Results

A total of 603 cross-border cholera cases with 5 deaths were recorded in Malawi and Uganda in 2015. Uganda recorded 118 cases with 2 deaths and CFR of 1.7%. The under-fives and school going children were the most affected age groups contributing 24.2% and 36.4% of all patients seen along Malawi-Mozambique and Uganda-DRC borders, respectively. These outbreaks lasted for over 3 months and spread to new areas leading to 60 cases with 3 deaths, CRF of 5%, and 102 cases 0 deaths in Malawi and Uganda, respectively. Factors contributing to these outbreaks were: poor sanitation and hygiene, use of contaminated water, floods and rampant cross-border movements. The outbreak control efforts mainly involved unilateral measures implemented by only one of the affected countries.

Conclusions

Cross-border cholera outbreaks contribute to the high annual reported cholera burden in Sub-Saharan Africa yet they remain silent, marginalized and poorly identified by cholera actors (governments and international agencies). The under-fives and the school going children were the most affected age groups. To successfully prevent and control these outbreaks, guidelines and strategies should be reviewed to assign clear roles and responsibilities to cholera actors on collaboration, prevention, detection, monitoring and control of these epidemics.

Highlights of the 8th International Conference on Vaccines for Enteric Diseases: the Scottish Encounter To Defeat Diarrheal Diseases

Infectious diarrhea is a leading cause of morbidity and of mortality; the burden of disease affects individuals of all ages but particularly young children, especially those living in poor regions where the disease is endemic. It is also a health concern for international travelers to these areas. Experts on vaccines and enteric infections and advocates for global health improvement gathered in Scotland from 8 to 10 July 2015 to discuss recent advances in the assessment and understanding of the burden of enteric diseases and progress in the development and implementation of strategies to prevent these infections. Highlights of the meeting included description of advances in molecular assays to estimate pathogen-specific prevalence, methods to model epidemiologic trends, novel approaches to generate broad-spectrum vaccines, new initiatives to evaluate vaccine performance where they are most needed, renewed interest in human challenge models, immunological readouts as predictors of vaccine efficacy, maternal immunization to prevent enteric infections, and the impact of maternal immunity on the vaccine take of infants. A follow-up scientific gathering to advance Shigella and enterotoxigenic Escherichia coli (ETEC) vaccine efforts will be held from 28 to 30 June 2016 in Washington, DC.

Oral Cholera Vaccine Coverage, Barriers to Vaccination, and Adverse Events following Vaccination, Haiti, 2013

In 2013, the first government-led oral cholera vaccination (OCV) campaign in Haiti was implemented in Petite Anse and Cerca Carvajal. To evaluate vaccination coverage, barriers to vaccination, and adverse events following vaccination, we conducted a cluster survey. We enrolled 1,121 persons from Petite Anse and 809 persons from Cerca Carvajal, categorized by 3 age groups (1-4, 5-14, >15 years). Two-dose OCV coverage was 62.5% in Petite Anse and 76.8% in Cerca Carvajal. Two-dose coverage was lowest among persons >15 years of age. In Cerca Carvajal, coverage was significantly lower for male than female respondents (69% vs. 85%; p<0.001). No major adverse events were reported. The main reason for nonvaccination was absence during the campaign. Vaccination coverage after this campaign was acceptable and comparable to that resulting from campaigns implemented by nongovernmental organizations. Future campaigns should be tailored to reach adults who are not available during daytime hours.