Public health. The cholera crisis in Africa.

Indian Council of Medical Research, Ansari Nagore, New Delhi, 110029, India.
Science (Impact Factor: 31.48). 06/2009; 324(5929):885. DOI: 10.1126/science.1173890
Source: PubMed

ABSTRACT In July 1994, 500,000 to 800,000 Rwandans crossed the border into the North Kivu region of Zaire (now called the Democratic
Republic of the Congo, DRC). During the first month after the influx, almost 50,000 refugees died; cholera was a major contributor

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    ABSTRACT: During the current seventh Cholera pandemicseventh Cholera pandemic , AfricaAfrica bore the major brunt of global disease burden. More than 40 years after its resurgence in Africa in 1970, cholera remains a grave public health problem, characterized by large disease burden, frequent outbreaks, persistent endemicityendemicity , and high CFRsCFRs , particularly in the region of the central African Great LakesGreat Lakes which might act as reservoirsreservoirs for cholera. There, cases occur year round with a rise in incidence during the rainy season. Elsewhere in sub-Saharan Africa, cholera occurs mostly in outbreaks of varying size with a constant threat of widespread epidemics. Between 1970 and 2011, African countries reported 3,221,050 suspected cholera cases to the World Health OrganizationWorld Health Organization , representing 46 % of all cases reported globally. Excluding the Haitian epidemic, sub-Saharan Africa accounted for 86 % of reported cases and 99 % of deaths worldwide in 2011. The number of cholera cases is possibly much higher than what is reported to the WHO due to the variation in modalities, completeness, and case definition of national cholera data. One source on country specific incidence rates for Africa, adjusting for underreporting, estimates 1,341,080 cases and 160,930 deaths (52.6 % of 2,548,227 estimated cases and 79.6 % of 209,216 estimated deaths worldwide). Another estimates 1,411,453 cases and 53,632 deaths per year, respectively (50 % of 2,836,669 estimated cases and 58.6 % of 91,490 estimated deaths worldwide). Within Africa, half of all cases between 1970 and 2011 were notified from only seven countries: AngolaAngola , Democratic Republic of the CongoDemocratic Republic of the Congo , MozambiqueMozambique , NigeriaNigeria , SomaliaSomalia , TanzaniaTanzania , and South AfricaSouth Africa . In contrast to a global trend of decreasing case fatality ratios (CFRs), CFRs have remained stable in Africa at approximately 2 %. Early propagation of cholera outbreaks depends largely on the extent of individual bacterial shedding, host and organism characteristics, the likelihood of people coming into contact with an infectious dose of Vibrio cholerae and on the virulence of the implicated strain. Cholera transmission can then be amplified by several factors including contamination of human water-water sources or food sourcesfood sources ; climate and extreme weather eventsextreme weather events ; political and economic crisescrises ; high population densitypopulation density combined with poor quality informal housinginformal housing and poor hygienehygiene practices; spread beyond a local community through human travel and animals, e.g., water birds. At an individual level, cholera risk may increase with decreasing immunityimmunity and hypochlorhydriahypochlorhydria , such as that induced by Helicobacter pylori Helicobacter pylori infection, which is endemic in much of Africa, and may increase individual susceptibilitysusceptibility and cholera incidence. Since contaminated water is the main vehicle for the spread of cholera, the obvious long-term solution to eradicateeradicate the disease is the provision of safe water to all African populations. This requires considerable human and financial resources and time. In the short and medium term, vaccinationvaccination may help to prevent and control the spread of cholera outbreaks. Regardless of the intervention, further understanding of cholera biology and epidemiology is essential to identify populations and areas at increased risk and thus ensure the most efficient use of scarce resources for the prevention and control of cholera.
    Current topics in microbiology and immunology 05/2014; DOI:10.1007/82_2014_369 · 3.47 Impact Factor
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    ABSTRACT: Vibrio cholerae O1, the causative agent of the disease cholera, has two biotypes namely the classical and El Tor. biotype is a subspecific taxonomic classification of V. cholerae O1. Differentiation of V. cholerae strains into biotype does not alter the clinical management of cholera but is of immense public health and epidemiological importance in identifying the source and spread of infection, particularly when V. cholerae is first isolated in a country or geographic area. From recorded history, till date, the world has experienced seven pandemics of cholera. Among these, the first six pandemics are believed to have been caused by the classical biotype whereas the ongoing seventh pandemic is caused by the El Tor biotype. In recent years, new pathogenic variants of V. cholerae have emerged and spread throughout many Asian and African countries with corresponding cryptic changes in the epidemiology of cholera. In this chapter, we describe the outbreaks during the seventh pandemic El Tor biotype era spanning more than five decades along with the recent advances in our understanding of the development, evolution, spread, and impact of the new variants of El Tor strains.
    Current topics in microbiology and immunology 02/2014; DOI:10.1007/82_2014_363 · 3.47 Impact Factor
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    ABSTRACT: Analysis of genes required for host infection will provide clues to the drivers of evolutionary fitness of pathogens like Vibrio cholerae, a mounting threat to global heath. We used transposon insertion site sequencing (Tn-seq) to comprehensively assess the contribution of nearly all V. cholerae genes toward growth in the infant rabbit intestine. Four hundred genes were identified as critical to V. cholerae in vivo fitness. These included most known colonization factors and several new genes affecting the bacterium's metabolic properties, resistance to bile, and ability to synthesize cyclic AMP-GMP. Notably, a mutant carrying an insertion in tsiV3, encoding immunity to a bacteriocidal type VI secretion system (T6SS) effector VgrG3, exhibited a colonization defect. The reduced in vivo fitness of tsiV3 mutants depends on their cocolonization with bacterial cells carrying an intact T6SS locus and VgrG3 gene, suggesting that the V. cholerae T6SS is functional and mediates antagonistic interbacterial interactions during infection.
    Cell host & microbe 12/2013; 14(6):652-663. DOI:10.1016/j.chom.2013.11.001 · 12.19 Impact Factor

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