Estimating the prevalence of infectious diseases from under-reported age-dependent compulsorily notification databases

Regional differences and temporal trend analysis of Hepatitis B in Brazil

BACKGROUND

Burden disease related to chronic HBV infection is increasing worldwide. Monitoring Hepatitis B occurrence is difficult due to intrinsic characteristics of the infection, nonetheless analyzing this information improves strategic planning towards reducing the burden related to chronic infection. In this line of thought, this study aims to analyze national and regional epidemiology of Hepatitis B and it's temporal trends based on Brazilian reported cases.

METHODS

Data obtained from the Brazilian National Notifiable Disease Reporting System (SINAN) from 2007 to 2018 were classified by infection status with an original classification algorithm, had their temporal trends analyzed by Joinpoint regression model and were correlated with gender, age and region.

RESULTS

Of the 487,180 hepatitis B cases notified to SINAN, 97.65% had it infection status correctly classified by the new algorithm. Hepatitis B detection rate, gender and age-distribution were different among Brazilian regions. Overall, detection rates remained stable from 2007 to 2018, achieving their maximal value (56.1 cases per 100,000 inhabitants) in North region. However, there were different temporal trends related to different hepatitis B status and age. Women mean age at notification were always inferior to those of men and the difference was higher in Central-West, North and Northeast regions.

CONCLUSION

Hepatitis B affects heterogeneously different populations throughout Brazilian territory. The differences shown in its temporal trends, regional, gender and age-related distribution helps the planning and evaluation of control measures in Brazil.

Incidence, Demographic, and Seasonal Risk Factors of Infections Caused by Five Major Enteric Pathogens, Ontario, Canada, 2010-2017

In Canada, enteric infections cause significant health and economic burden. We evaluated the individual characteristics of laboratory-confirmed cases of Campylobacter spp. (n = 28,728), non-typhoidal Salmonella spp. (n = 22,640), Yersinia spp. (n = 1674), Verotoxin-producing Escherichia coli (VTEC; n = 1340), and Listeria monocytogenes (n = 471), reported between 2010 and 2017 inclusive, in Ontario, Canada (population ∼13,500,000). We calculated overall and pathogen-specific annual and mean incidence rates (IRs) for Ontario. We used multivariable Poisson and negative binomial regression models to estimate incidence rate ratios (IRRs) for years, seasons, age groups, and sexes, and we included two-way age and sex interaction terms in the models. Campylobacter and Salmonella infections had the highest IRs whereas Listeria infections had the lowest IRs. None of the infections showed long-term trends over the 8-year study period; however, rates of all five infections were elevated in the summer. More Salmonella, VTEC, and Listeria infections were linked to disease outbreaks than were Campylobacter and Yersinia infections. Overall, mean IRs of Campylobacter, Salmonella, Yersinia, and VTEC infections were highest in children 0-4 years old, whereas Listeria IRs peaked in adults 60 years and older. Higher mean IRs of Campylobacter were observed in males. No other differences by sex were statistically significant. The same mean rate was observed in both sexes for Listeria. Adjusting for all other factors, significant age- and sex-specific differences in IRs were observed in Campylobacter, Salmonella, and VTEC infection rates. No significant interactions of age and sex were found for Yersinia and Listeria infections. Future research should focus on the pathogen-specific socioeconomic, environmental, or agricultural risk factors that might be responsible for these infections.

Assessing the reporting of Dengue, Chikungunya and Zika to the National Surveillance System in Colombia from 2014-2017: A Capture-recapture analysis accounting for misclassification of arboviral diagnostics

BACKGROUND

Chikungunya, dengue, and Zika are three different arboviruses which have similar symptoms and are a major public health issue in Colombia. Despite the mandatory reporting of these arboviruses to the National Surveillance System in Colombia (SIVIGILA), it has been reported that the system captures less than 10% of diagnosed cases in some cities.

METHODOLOGY/PRINCIPAL FINDINGS

To assess the scope and degree of arboviruses reporting in Colombia between 2014-2017, we conducted an observational study of surveillance data using the capture-recapture approach in three Colombian cities. Using healthcare facility registries (capture data) and surveillance-notified cases (recapture data), we estimated the degree of reporting by clinical diagnosis. We fit robust Poisson regressions to identify predictors of reporting and estimated the predicted probability of reporting by disease and year. To account for the potential misclassification of the clinical diagnosis, we used the simulation extrapolation for misclassification (MC-SIMEX) method. A total of 266,549 registries were examined. Overall arboviruses' reporting ranged from 5.3% to 14.7% and varied in magnitude according to age and year of diagnosis. Dengue was the most notified disease (21-70%) followed by Zika (6-45%). The highest reporting rate was seen in 2016, an epidemic year. The MC-SIMEX corrected rates indicated underestimation of the reporting due to the potential misclassification bias.

CONCLUSIONS

These findings reflect challenges on arboviruses' reporting, and therefore, potential challenges on the estimation of arboviral burden in Colombia and other endemic settings with similar surveillance systems.

Population attributable fractions of mortality in people living with HIV: roles of delayed antiretroviral therapy, hepatitis coinfections and social factors

OBJECTIVES

Despite free access to antiretroviral therapy (ART) from 1996 onward, and treatment for all people living with HIV (PLWHIV) from 2013, mortality in Brazil has not homogeneously decreased. We investigated to what extent delayed ART, hepatitis coinfections and sociodemographic factors predict all-cause mortality in Brazilian PLWHIV.

DESIGN

We included PLWHIV at least 18 years, with complete CD4 cell count data, followed up between 2007 and 2015 in Brazil.

METHODS

After multiple imputation, an extended Cox model helped estimate the effects of fixed and time-varying covariates on mortality.

RESULTS

The study population (n = 411 028) were mainly male (61%), white (55%), 40 years or less (61%), heterosexually HIV infected (71%), living in the Southeast region (48%) and had basic education (79%). Hepatitis C virus and hepatitis B virus coinfection prevalences were 2.5 and 1.4%, respectively. During a 4-year median follow-up, 61 630 deaths occurred and the mortality rate was 3.45 (95% confidence interval: 3.42-3.47) per 100 person-years. Older age, male sex, non-white ethnicity, illiteracy/basic education and living outside the Southeast and Central-West regions were independently associated with increased mortality. The main modifiable predictors of mortality were delayed ART (i.e. CD4 cell count <200 cells/μl at ART initiation) (adjusted population attributable fraction: 14.20% [95% confidence interval: 13.81-14.59]), being ART-untreated (14.06% [13.54-14.59]) and ART-treated with unrecorded CD4 at ART initiation (5.74% [5.26-6.21]). Hepatitis C virus and hepatitis B virus coinfections accounted for 2.44 [2.26-2.62] and 0.42% [0.31-0.53] of mortality, respectively.

CONCLUSION

The current study demonstrates that besides early ART and coinfection control, actions targeting males, non-whites and illiterate people and those with basic education are important to reduce avoidable deaths among Brazilian PLWHIV.

Laboratory capacity of Greek hospitals for diagnosis of salmonellosis and surveillance systems' performance in the years of economic crisis, 2010-2016

Austerity might have affected the capacity of public hospitals in Greece to diagnose salmonellosis (laboratory capacity) over the period 2010-2016, as well as the performance of the existing surveillance systems. The scope of this paper is to present data on laboratory capacity over these years, as well as the results of a two-source capture-recapture study (data from Mandatory Notification System and National Reference Laboratory System for Salmonella). The main findings were that: (a) laboratory capacity was high and steady besides the financial crisis, (b) the estimated number of laboratory-confirmed cases (n = 6017, 95% CI 5892-6142) resulted in an incidence rate (7.9 cases/100 000 population) almost twice than that reported by the two systems Mandatory Notification System (MNS); 4.1 and National Reference Laboratory System (NRLS); 4.5 cases/100 000 population, (c) underreporting was high for both systems (MNS; 47.5% and NRLS; 42.8%) and (d) differences by geographical region, size and type of hospital were identified. We suggest that (a) specific interventions are needed to increase completeness of the systems by type of hospital and geographical region, (b) record linkage can help in estimating the disease burden in a more valid way than each system separately and (c) a common electronic database in order to feed one system to the other could significantly increase completeness of both systems.