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Mycobacterium ulcerans infection or Buruli ulcer begins by a papule, nodule, blotch or oedema and develops into ulceration with complications which can lead to disabilities. Its prevalence is high in West Africa and in Côte d'Ivoire particularly. Until recently, only ulcerated forms were mostly observed, whereas nodular ones were unnoticed or did not draw patients' attention. From 1999 to 2002 we conducted a before-after survey in the endemic area of Zoukougbeu located in Daloa region, the central west part of Côte d'Ivoire in order to assess the potential impact of a screening and treatment strategy for nodular forms of Buruli ulcer on ulceration rate decrease. The survey used clinical criteria necessary to identify Buruli ulcer nodule which were defined according to a former study carried out in the same area in 1998. As result of our survey 781 Buruli ulcer cases were reported of which 34.7% were ulcerative forms, 61.1% were nodules and 4.2% were other forms (blotch and oedema). By comparing the data of 1999, when the prevention program started, to those of 2002, we observed a drop of 47.6% in the ulcerative lesions and an increase of 57.4% in nodule ones. These changes were statistically significant (p < 10-5). Annual trend, from 1999 to 2002, showed a decrease in the detection rate of the respective forms under study. It ranged from 25.8/10000 to 7.3/10000 for ulcerative lesions and from 23/10000 to 19.7/10000 for nodules. In spite of possible defects in the methodology of a before/after survey the incidence decrease of both ulcerative and nodular forms that coincided with the prevention program probably reflects the efficacy of the secondary prevention program that promotes early diagnosis and treatment of nodular forms of Mycobacterium ulcerans infection.

Mycobacterium ulcerans infection (Mu) is an emerging public health problem. The cumulative number of cases in Ivory Coast was 10,382 in 1997. One of the key points of the Yamoussoukro "global initiative" in December 1997 involved detection and treatment of cases at the early-disease stage. The threefold purpose of this transversal study was to determine the frequency of nodular-stage Mu infection, to describe the features of the nodules, and to identify nodular features suitable for early screening use. Of the 93 nodules removed, 58.1% were due to Mu, indicating that the prevalence of nodular-stage Mu in Zoukougbeu, Ivory Coast was 9 per 1000 inhabitants. All Mu nodules were recent, caused pruritus, and displayed oedematous edges. The mean duration of disease was 23 months. In endemic areas, Mu infection should be suspected for any lesion that is of recent onset (< 5 year), shows visible elevation, has a diameter of 3 cm or more, or is mobile under the skin. Cold nodules that are adherent to the superficial skin layer and located on the limbs or firm cold nodules should also be considered as suspect. Excision of cold nodules caused by Mu is recommended. The wound heals within 4 weeks and no recurrences have been reported after 6-month follow-up.