Geographical distribution of typhoid risk factors in low and middle income countries

Abstract

BackgroundWhile the global burden of typhoid fever has been often brought up for attention, the detailed surveillance information has only been available for the limited number of countries. As more efficacious vaccines will be available in the near future, it is essential to understand the geographically diverse patterns of typhoid risk levels and to prioritize the right populations for vaccination to effectively control the disease.MethodsA composite index called the typhoid risk factor (TRF) index was created based on data with the Global Positioning System (GPS). Demographic and Health Surveys (DHS) and National Geographical Data Center (NGDC) satellite lights data were used for this analysis. A count model was adopted to validate the TRF index against the existing surveillance burden data. The TRF index was then re-estimated for 66 countries using the most recent data and mapped out for two geographical levels (sub-national boundary and grid-cell levels).ResultsThe TRF index which consists of drinking water sources, toilet facility types, and population density appeared to be statistically significant to explain variation in the disease burden data. The mapping analysis showed that typhoid risk levels vary not only by country but also by sub-national region. The grid-cell level analysis highlighted that the distribution of typhoid risk factors is uneven within the sub-national boundary level. Typhoid risk levels are geographically heterogeneous.ConclusionsGiven the insufficient number of surveillance studies, the TRF index serves as a useful tool by capturing multiple risk factors of the disease into a single indicator. This will help decision makers identify high risk areas for typhoid as well as other waterborne diseases. Further, the study outcome can guide researchers to find relevant places for future surveillance studies.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-016-2074-1) contains supplementary material, which is available to authorized users.

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“…These data concur with the geographical distribution of typhoid fever, placing it in developing countries, which converge geo-spatially in the tropic of cancer, having a tropical climate (Lee et al, 2016). However, although…”

“…An example of this are the high incidence of typhoid fever in states such as Sinaloa and Tamaulipas (DGE, 2017) and paratyphoid/ other salmonellosis in Chiapas, Veracruz and Tabasco; these states have similar temperature and rainfall and are hit by cyclones and hurricanes (CONAGUA 2013; Revista Bio Ciencias 6(nesp), e540. se presenta el mayor número de casos de salmonelosis (DGE, 2017).Estos datos concuerdan con la distribución geográfica de fiebre tifoidea ubicándola en países en vías de desarrollo, los cuales convergen geo-espacialmente en el trópico de cáncer, y cuentan con un clima tropical(Lee et al, 2016). Salmonella a periodos de lluvia en sitios como Bahía de Todos Santos, Baja California, México; mientras los segundos, detectando a la bacteria de manera consistente independientemente de la estación del año en ríos de Sinaloa.…”

Extended-spectrum beta-lactamases producing extensively drug-resistant Salmonella Typhi in Punjab, Pakistan

“…The incidence rates in some countries of Asia and Africa indicate the critical gaps in knowledge and surveillance system in these regions [29,30]. The evidence-based approaches are essential to bridge the gaps and to screen the broader regions in these continents.…”

Complications of typhoid fever in digestive surgery: a descriptive study based on 295 cases in a sub Saharan environment

“…Typhoid fever is a systemic and contagious infection caused by Salmonella typhi, or more rarely, by Salmonella paratyphi A, B, or C [1]. It is currently considered a disease of poverty [2,3]. According to the World Health Organization (WHO), its incidence reaches 21 million cases per year worldwide, and its mortality is approximately 4% [4,5].…”