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Letter
Buruli Ulcer Distribution
in Benin
Roch Christian Johnson,* Michel Makoutodé,† Ghislain Emmanuel Sopoh,*
Pierre Elsen,‡ Jules Gbovi,* Lise Hélène Pouteau,§ Wayne M. Meyers,¶ Michel
Boko,# and Françoise Portaels‡
*Programme National de Lutte contre I'Ulcère e Buruli, Cotonou, Benin;
†Institut Régional de Santé Publique (IRSP), Ouidah, Benin; ‡Institute
of Tropical Medicine, Antwerp, Belgium; §Médecins sans Frontières-Luxembourg,
Cotonou, Benin; ¶Armed Forces Institute of Pathology, Washington, DC,
USA; and #Université d'Abomey, Calavi, Benin
Suggested
citation for this article
To the Editor: Mycobacterium ulcerans disease, commonly
called Buruli ulcer, is an emerging infectious disease in West Africa
(1,2). Several forms of Buruli ulcer exist; large, chronic
ulcerations or indurated plaques of the skin are the most frequent manifestations
of the disease (1), and bone is sometimes involved (3).
Little is known about the focal epidemiology of Buruli ulcer; incidence,
prevalence, and other data are usually reported at the national or district
level (4). These data convey the importance of the disease
but do not show the wide variations that occur at the village level within
a given district. In 2002, we investigated the disease in an arrondissement
(Gnizounmé) in an area in which Buruli ulcer is endemic, the commune of
Lalo in Benin. Prevalence rates of Buruli ulcer varied from 0.58 to 32.62
per 1,000 inhabitants of villages in the same arrondissement. For Gnizounmè
Arrondissement, the overall prevalence was 10.70 per 1,000 inhabitants.
These results confirmed that distribution of Buruli ulcer must be determined
at geopolitical divisions lower than district or national levels, as is
frequently assumed to be the case.
An inverse relationship exists between the prevalence of Buruli ulcer
and distance from the Couffo River, which drains the arrondissement of
Gnizounmè. A comparison of the relevant data for Assogbahoué and Tandji
villages shows that the number of patients per 1,000 inhabitants increases
gradually from 0.58 to 32.62 as the distance from the river decreases
from 10 to 1 km.
Recently, aquatic insects have been considered potential vectors of M.
ulcerans (5,6). These aquatic insects can fly many
kilometers from their source (7). This finding may partially
explain how patients who live farther distances from their source of water
become infected, but not as often as those who live closer. Some water
bugs obtained from water collection points along the Couffo River in the
village of Tandji were found to be positive for M. ulcerans by
using PCR with specific insertion sequence 2404 as a target (8).
If we consider domestic water sources in the arrondissement of Gnizounmè,
only Tandji (32.62 Buruli ulcer patients per 1,000 inhabitants) used water
directly from the Couffo River. Other villages employed protected water
sources for domestic purposes (boreholes, cisterns, or piped water from
artesian wells). These results are similar to Barker's findings in Uganda,
which showed that families who used unprotected sources of water for domestic
purposes had higher prevalence rates of Buruli ulcer than those who used
boreholes (9). Consequently, besides the possible influence
of distance from the river on disease prevalence through potential vectors,
such as insects or other factors, we hypothesize that the use of river
water for domestic purposes may also play a role in the elevated prevalence
of the disease in Tandji village. If this hypothesis is confirmed, preventive
public health programs based on strategies that provide protected water
supply systems to villages must be developed to reduce the frequency of
the disease.
Determining the complex relationship between distance from the Couffo
River and the numbers of cases and level of protection of water supply
is difficult. Our findings argue for the need to perform additional epidemiologic
studies to understand more completely the key factors that determine the
distribution of the disease in the entire commune of Lalo.
References
- Asiedu K, Scherpbier R, Raviglione M. Buruli ulcer—Mycobacterium
ulcerans infection. Geneva: World Health Organization; 2000.
- Debacker M, Aguiar J, Steunou C, Zinsou C, Meyers WM, Guédénon A,
et al. Mycobacterium
ulcerans disease (Buruli ulcer) in a rural hospital, southern Benin,
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insect as a vector for Mycobacterium ulcerans. Appl Environ
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Suggested citation
for this article:
Johnson RC, Makoutodé
M, Sopoh GE, Elsen P, Gbovi J, Pouteau LH, et al. Buruli ulcer distribution
in Benin [letter]. Emerg Infect Dis [serial on the Internet]. 2005 Mar
[date cited]. Available from http://www.cdc.gov/ncidod/EID/vol11no03/04-0597.htm
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