Analysing the utility of implementation of the new oral cholera vaccine. A case-study in west-africa
- J Guerra
- R Gray
- A Djibo
- L Monzo
- B Mayana
- Maladies diarrhéiques
An epidemic of cholera is defined as at least one case of cholera in a given non-endemic region.
In epidemic settings, about 20% of infected people present large volume watery diarrhoea.
Mortality of untreated cases can reach 50%, because of severe and rapidly progressing dehydratation and shock (1).
Given the new data on oral cholera vaccines effectiveness, feasibility and acceptance in cholera affected-populations, WHO recommends to target cholera vaccination in high-risk areas and population groups (4): "Vaccination should be targeted at areas where 2 of the following criteria have been met: (i) cultureconfirmed cholera has been detected in at least 3 of the past 5 years; (ii) an
incidence rate of cholera of at least 1/ 1000 population in any of these years has been recorded; (iii) if population-based incidence rates are not available, highrisk areas or groups have been identified using information collected from local public health officials".
Shanchol® is a new inactive whole cell oral cholera vaccine with a two year known protective efficacy of 67% in people aged 5 years old or more, and 49% in 1-4 year-old chidren (2). An initial vaccination with 2 doses two weeks apart followed by a booster dose every two years is recommended. Besides providing individual immunity, Shanchol® is likely to confer herd protection (3).
We therefore conducted a study to evaluate the utility of such a vaccination in the region of Maradi in Niger (figure 1). This objective needed a previous evaluation of the regional cholera surveillance system.