Full Length Research Paper

Risk factors for Buruli ulcer in Côte d’Ivoire: Results of a case-control study, August 2001

Laurence Ahoua^1,2*, Aka N. Guetta¹, Euloge Ekaza¹, Samir Bouzid¹, Raymond N’Guessan¹ and Mireille Dosso¹

¹Bacteriological and virological laboratory, Institut Pasteur, 01 B. P. 490, Abidjan Côte d’Ivoire.

²Epicentre, 8 rue Saint Sabin 75011 Paris, France.

*Corresponding author. E-mail: epimail@epicentre.msf.org or lahoua@epicentre.msf.org.  Phone: + 331-421-2849; Fax: + 331-40-21-28-03.

Accepted 22 January, 2009

A case-control study was carried out in 3 highly endemic regions of Côte d’Ivoire to study risk factors for Buruli ulcer. A case was defined as a Buruli ulcer occurring less than one year before the date of survey, resident in one of the regions investigated and there was no history of Buruli ulcer illness. Controls were selected from the general population by a two stage cluster sampling method. A total of 116 cases and 116 controls were included. For the cases, the male/female sex ratio was 0.84, the median age was 19.5 years and 40.5% were children ≤ 15 years. Biological results were obtained for 86 (74%) cases using skin exudate samples. Positive rates were 22.0, 22.1 and 27.9% respectively for smear examination, culture and PCR IS2404, respectively. After adjusting for possible confounders, no history of BCG vaccination (OR_a = 5.0, CI 1.7 - 14.3), presence of a case ≤15 years (OR_a = 8.3, CI 2.8 - 24.1), having a river/lake/dam near the housing (OR_a = 4.4, CI 1.6 - 12.2) and the type of place for fishing (p = 0.001) were associated with illness. Young children and women having daily water related activities were most at risk. Swab samples were not sensitive enough for Buruli ulcer diagnosis. There is an urgent need for a rapid field test to diagnosis Buruli Ulcer as PCR IS2404 remains expensive for most of the endemic countries.

Key words: Ulcer, Mycobacterium ulcerans, Côte d’Ivoire, case-control study, risk factors.