Melissa Carbine and Dr. McKay Rollins, Health Sciences
M. ulcerans infection (commonly referred to as Buruli ulcer) is rapidly emerging as an important cause of human morbidity throughout the world. An indolent, deep, necrotizing lesion of the skin, Buruli ulcer is caused by Mycobacterium ulcerans (Meyers et al., 1997). The destruction of the skin tissue often leaves patients disfigured and/or severely handicapped, generating a public health dilemma with significant socioeconomic implications.
M. ulcerans infection remains the third most common mycobacterial infection after tuberculosis and leprosy. Today, M. ulcerans infection is found in 26 different countries mostly within the tropic or sub-tropic regions.1 A dramatic increase of incidences reported in the last few years have been found in several West African countries including: Benin, Cote d’Ivoire, and Ghana.
The disease occurs within a closely defined region near environmental reservoirs associated with water sources such as a river or lake. The mode of transmission remains unknown. Infection is suggested to be acquired through direct inoculation into the skin of areas where specific trauma has occurred leaving open wounds or abrasions. These wounds can then become infected by mud or grasses contaminated with Mycobacterium ulcerans (1).
This study describes a series of 85 cases of Mycobacterium ulcerans infection from a chronic endemic focus in the Ashanti Region of Ghana. 75% of the cases were children 15 years or younger. In the distribution of cases, 38 were male and 47 were female. The highest rate of illness occurred in the 8-15 year old age group resulting in 41% of the total cases. Eleven (13%) of the patients interviewed suffered minor to severe deformities, including 1 limb amputation, loss of sight for one child, and 1 fatality due to an unknown cause(s). A significantly high incidence rate was seen in the residential area known as the “Mission”. Use of differing water sources was also associated with higher incidence rates.
Examination of a series of retrospective cases of Mycobacterium ulcerans infection from the endemic village of Tontokrom was conducted in order to determine the extent of the disease as well as assess possible risk factors. Standardized questionnaires, based on the World Health Organization’s Recording Form for Buruli Ulcer, were administered to both case and control groups to gather basic demographic and history data. The following information was also included in the questionnaire: residence location, footpath(s) taken when going to farm location, and water sources (drinking, bathing, and laundry).
M. ulcerans infection occurs among rural populations in difficult to reach areas in Ghana. Results from this survey are conclusive with other reported findings in respect to age and gender. However, no conclusive data have demonstrated why children 15 and younger consistently seem to be burdened more by M. ulcerans infection throughout endemic countries in Africa.
Meanwhile, significant means of identifying possible point sources in this study included residential patterns, footpaths and water sources. Residential patterns, were statistically significant (P < .001) in one region of the village, a church-owned area known as the Mission. Twenty-nine cases of M. ulcerans infection were identified in the 42 households, resulting in the highest point prevalence rate (7.5 per 100) for the village (95% CI 1.40, 3.54). Similarly, though not statistically significant (P = .064), M. ulcerans infected patients used Footpath # 3, located on the North-East side of the village, more than any other.
The case-control analysis of Borehole # 3 revealed a higher rate of use among M. ulcerans patients (30.0%) than by the control group (19.2%). Tests of significance concluded P = .007 with a 95% confidence interval of (1.17, 2.79). Use of Asuafo stream was recorded 18 times by the case group (16%) and 23 times by the control group (2.2%). The observed difference between these two groups was statistically significant with a 95% confidence interval of (4.44, 16.4) and P < .001.
From the evidence presented, it would appear M. ulcerans infection is contracted by contact at distinct locations (e.g. borehole, stream, etc.) in or near the village. Nevertheless, considerable systematic environment sampling is needed in the area. Further important findings concern additional potential factors contributing to susceptibility.
We observed no significant difference among cases and controls with regards to BCG vaccination, reported to be a possible means of prevention of M. ulcerans infection. Similarly, neither trauma nor travel to other endemic communities presented a reliable means of identifying the mode of transmission. Applicable preventative measures and mode of transmission possibilities require additional research.
M. ulcerans infection remains a constant and important health threat because of the end results of severe disfiguration and/or handicaps. With the mode of transmission unknown, education remains the most effective prevention strategy. Additional research needs to be conducted among those that are 15 years or younger and also on contributing environmental sources.
- Meyers, W.M. & Horsburgh, C.R., Jr. (1997). pp. 119-133. Pathology of Emerging Infections. Washington D.C.: American society for Microbiology