Dataset Information

Spatio-temporal patterns and landscape-associated risk of Buruli ulcer in Akonolinga, Cameroon.

ABSTRACT:

Background

Buruli ulcer (BU) is an extensively damaging skin infection caused by Mycobacterium ulcerans, whose transmission mode is still unknown. The focal distribution of BU and the absence of interpersonal transmission suggest a major role of environmental factors, which remain unidentified. This study provides the first description of the spatio-temporal variations of BU in an endemic African region, in Akonolinga, Cameroon. We quantify landscape-associated risk of BU, and reveal local patterns of endemicity.

Methodology/principal findings

From January 2002 to May 2012, 787 new BU cases were recorded in 154 villages of the district of Akonolinga. Incidence per village ranged from 0 (n = 59 villages) to 10.4 cases/1000 person.years (py); median incidence was 0.4 cases/1,000 py. Villages neighbouring the Nyong River flood plain near Akonolinga town were identified as the highest risk zone using the SPODT algorithm. We found a decreasing risk with increasing distance to the Nyong and identified 4 time phases with changes in spatial distribution. We classified the villages into 8 groups according to landscape characteristics using principal component analysis and hierarchical clustering. We estimated the incidence ratio (IR) associated with each landscape using a generalised linear model. BU risk was highest in landscapes with abundant wetlands, especially cultivated ones (IR = 15.7, 95% confidence interval [95%CI]?= 15.7[4.2-59.2]), and lowest in reference landscape where primary and secondary forest cover was abundant. In intermediate-risk landscapes, risk decreased with agriculture pressure (from IR[95%CI]?= 7.9[2.2-28.8] to 2.0[0.6-6.6]). We identified landscapes where endemicity was stable and landscapes where incidence increased with time.

Conclusion/significance

Our study on the largest series of BU cases recorded in a single endemic region illustrates the local evolution of BU and identifies the Nyong River as the major driver of BU incidence. Local differences along the river are explained by wetland abundance and human modification of the environment.

SUBMITTER: Landier J

PROVIDER: S-EPMC4154661 | biostudies-literature | 2014 Sep

REPOSITORIES: biostudies-literature

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Publications

Spatio-temporal patterns and landscape-associated risk of Buruli ulcer in Akonolinga, Cameroon.

Landier Jordi J Gaudart Jean J Carolan Kevin K Lo Seen Danny D Guégan Jean-François JF Eyangoh Sara S Fontanet Arnaud A Texier Gaëtan G

PLoS neglected tropical diseases 20140904 9

<h4>Background</h4>Buruli ulcer (BU) is an extensively damaging skin infection caused by Mycobacterium ulcerans, whose transmission mode is still unknown. The focal distribution of BU and the absence of interpersonal transmission suggest a major role of environmental factors, which remain unidentified. This study provides the first description of the spatio-temporal variations of BU in an endemic African region, in Akonolinga, Cameroon. We quantify landscape-associated risk of BU, and reveal loc ...[more]

PMID: 25188464

Similar Datasets

Project description:BackgroundIn the Cameroon, previous efforts to identify Buruli ulcer (BU) through the mobilization of community health workers (CHWs) yielded poor results. In this paper, we describe the successful creation of a BU community of practice (BUCOP) in Bankim, Cameroon composed of hospital staff, former patients, CHWs, and traditional healers.Methods and principle findingsAll seven stages of a well-defined formative research process were conducted during three phases of research carried out by a team of social scientists working closely with Bankim hospital staff. Phase one ethnographic research generated interventions tested in a phase two proof of concept study followed by a three- year pilot project. In phase three the pilot project was evaluated. An outcome evaluation documented a significant rise in BU detection, especially category I cases, and a shift in case referral. Trained CHW and traditional healers initially referred most suspected cases of BU to Bankim hospital. Over time, household members exposed to an innovative and culturally sensitive outreach education program referred the greatest number of suspected cases. Laboratory confirmation of suspected BU cases referred by community stakeholders was above 30%. An impact and process evaluation found that sustained collaboration between health staff, CHWs, and traditional healers had been achieved. CHWs came to play a more active role in organizing BU outreach activities, which increased their social status. Traditional healers found they gained more from collaboration than they lost from referral.Conclusion/ significanceSetting up lines of communication, and promoting collaboration and trust between community stakeholders and health staff is essential to the control of neglected tropical diseases. It is also essential to health system strengthening and emerging disease preparedness. The BUCOP model described in this paper holds great promise for bringing communities together to solve pressing health problems in a culturally sensitive manner.

Project description:BackgroundBuruli ulcer (BU) is a chronic, indolent necrotizing disease of the skin and underlying tissues caused by Mycobacterium ulcerans, which may result in functional incapacity. In 2002, Médecins Sans Frontières (MSF) opened a BU programme in Akonolinga Hospital, Cameroon, offering antibiotic treatment, surgery and general medical care. Six hundred patients have been treated in the project to date. However, due to the nature of the disease and its stigmatization, determining the exact prevalence and burden of disease is difficult and current estimates may not reflect the magnitude of the problem. The objectives of this survey were to estimate the prevalence of BU in the health district of Akonolinga, describe the geographic extension of the highly endemic area within the health district, and determine the programme coverage and its geographical distribution.Methodology/principal findingsWe conducted a cross-sectional population survey using centric systematic area sampling (CSAS). A 15x15 km grid (quadrats of 225 km(2)) was overlaid on a map of Akonolinga district with its position chosen to maximize the area covered by the survey. Quadrats were selected if more than 50% of the quadrat was inside of the health district. The chiefdom located closest to the centre of each quadrat was selected and Buruli cases were identified using an active case finding strategy (the sensitivity of the strategy was estimated by capture-recapture). WHO-case definitions were used for nodules, plaque, ulcer, oedema and sequelae. Out of a total population of 103,000 inhabitants, 26,679 were surveyed within the twenty quadrats. Sensitivity of the case finding strategy was estimated to be 84% (95%CI 54-97%). The overall prevalence was 0.47% (n = 105) for all cases including sequelae and 0.25% (n = 56) for active stages of the disease. Five quadrats had a high prevalence of >0.6% to 0.9%, 5 a prevalence >0.3% to 0.6% and 10 quadrats <0.3%. The quadrats with the high prevalence were situated along the rivers Nyong and Mfoumou. Overall coverage of the project was 18% (12-27%) for all cases and 16% (9-18%) for active cases, but was limited to the quadrats neighbouring Akonolinga Hospital.Conclusions/significancePrevalence was highest in the area neighbouring the Nyong River. Coverage was limited to the area close to the hospital and efforts have to be made to increase access to care in the high prevalence areas. Use of the CSAS method was particularly useful for project planning and to identify priority areas of intervention. An added benefit of the method is that the survey procedure incorporated an awareness campaign, providing information about the disease and treatment to the population.

Dataset Information

Spatio-temporal patterns and landscape-associated risk of Buruli ulcer in Akonolinga, Cameroon.

Background

Methodology/principal findings

Conclusion/significance

Publications

Spatio-temporal patterns and landscape-associated risk of Buruli ulcer in Akonolinga, Cameroon.

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