Date Published: February 20, 2008
Publisher: Public Library of Science
Author(s): Jacqueline L. Deen, Lorenz von Seidlein, Dipika Sur, Magdarina Agtini, Marcelino E. S. Lucas, Anna Lena Lopez, Deok Ryun Kim, Mohammad Ali, John D. Clemens, Malla Rao
Abstract: BackgroundCholera remains an important public health problem. Yet there are few reliable population-based estimates of laboratory-confirmed cholera incidence in endemic areas around the world.MethodsWe established treatment facility–based cholera surveillance in three sites in Jakarta (Indonesia), Kolkata (India), and Beira (Mozambique). The annual incidence of cholera was estimated using the population census as the denominator and the age-specific number of cholera cases among the study cohort as the numerator.FindingsThe lowest overall rate was found in Jakarta, where the estimated incidence was 0.5/1000 population/year. The incidence was three times higher in Kolkata (1.6/1000/year) and eight times higher in Beira (4.0/1000/year). In all study sites, the greatest burden was in children under 5 years of age.ConclusionThere are considerable differences in cholera incidence across these endemic areas but in all sites, children are the most affected. The study site in Africa had the highest cholera incidence consistent with a growing impression of the large cholera burden in Africa. Burden estimates are useful when considering where and among whom interventions such as vaccination would be most needed.
Partial Text: Cholera is an acute, diarrheal illness caused by infection of the intestine with O1 or O139 serogroups of Vibrio cholerae. Profuse watery diarrhea and vomiting can lead to dehydration and shock. Without treatment, death can occur within hours. Oral and intravenous rehydration therapy has markedly decreased case fatality rates , but cholera remains a dreaded illness because of its rapid onset, severity, and potential to cause outbreaks that easily overwhelm public health systems in impoverished settings. Seasonal disease occurs in many less developed countries that cannot afford to establish or to maintain essential infrastructure for safe water supply and sanitation. Outbreaks may arise during natural disasters and complex emergencies.
We compared the annualized incidence (per 1,000 population) of cholera across the study sites (Figure 1 and Table 1). Overall rates ranged from 0.5 to 4.0 cases/1,000 population/year. The lowest overall rate was found in Jakarta, where the estimated incidence was 0.5/1,000/year. The incidence was three times higher in Kolkata (1.6/1000/year) and eight times higher in Beira (4.0/1000/year). The rates were highest in children under 5 years of age, with 8.8/1,000, 6.2/1,000, and 1.2/1000 among the 24 to 59 months old in Beira, Kolkata, and Jakarta, respectively. In the two sites where children under two years were also under observation (Jakarta and Kolkata), they were found to have even higher rates of cholera: 8.6/1,000 in Kolkata and 3.2/1,000 in Jakarta. Only V. cholerae O1 was isolated at all sites.
We found that young children bear the greatest burden of cholera. Cholera has traditionally been considered to occur infrequently in young children, and consequently, the WHO recommends that cholera should be suspected among those over two years of age who have acute watery diarrhea and severe dehydration if cholera is endemic in the local area . Aside from our data, two other studies have shown that cholera is a significant problem in young children ,, but neither provide population-based incidence. Our findings have implications for the enhanced benefit of cholera vaccination targeting specific age-groups in cholera-endemic areas. Protecting children against cholera may not only decrease the burden in this age group but decrease transmission of the disease to their family members and the community . Immunization of adult women with killed oral cholera vaccines has been shown to confer herd immunity against cholera to children too young to be vaccinated .