Skin neglected tropical diseases in Cameroon : the need for integrated control and elimination

Among the updated WHO list of 20 Neglected Tropical Diseases, about six manifests on the skin and are now known as Skin-NTDs. NTDs have not received equal attention from the international community compared to HIV/AIDS, malaria and tuberculosis although their burdens in terms of disability adjusted life years (DALYs) are comparable. Following advocacy for over a decade and half, NTDs are now being prioritized on the global health agenda, and the WHO has set a 2020 roadmap for accelerating work to overcome the global impact of NTDs.
For this PhD thesis, we aimed at determining the current burden of major skin-NTDs in Cameroon and make recommendations for proper control strategies. The basis was surveillance data from 2000 to 2014 for leprosy and Buruli ulcer available at the National Control Programme office, community-based surveys and a literature review.
We confirmed that Cameroon attained elimination of leprosy as a public health problem in 2000. Between 2000 and 2014, the leprosy prevalence and the detection dropped significantly, with the steepest reductions occurring between 2000 and 2005, followed by a stagnation from 2006 to 2014. We also showed a persistent but moderate transmission of leprosy, with an increasing trend between 2007 and 2014. Ten health districts had not achieved leprosy elimination, and eighteen were high leprosy-burdened according to the Leprosy Burden Score at the end of 2014. The increasing trend in leprosy transmission and the persistence of high-burdened districts were attributed to reduction in key leprosy control activities secondary to waning of resource allocation by the government and support partners. Some 3700 Buruli ulcer (BU) cases, with an annual average of 264 cases were treated from 2001 to 2014 in Cameroon. Control activities began in two endemic foci of Ayos and Akonolinga in the centre region and were later expanded to Ngoantet-Mbalmayo in the centre, Bankim in the Adamawa and Mbonge in the southwest regions following a national survey in 2004. Analysis of data from treatment centres created at these foci, further revealed presence of BU in 64 health districts mainly from the southern part of the country. BU case-detection increased between 2001 and 2005, and then declined progressively until 2014 and beyond. Analysis of key BU control indicators showed deterioration from 2010 to 2014 and beyond. We also highlighted the importance of differential diagnosis in a context of co-endemicity of mycobacterial diseases, through a case-report of cutaneous tuberculosis misdiagnosed for BU. BU activities in Cameroon were supported by two partners, who from 2010, reduce their support significantly to complete withdrawal of one of them in 2014. Currently there is little funding from the government budget, which is insignificant compared to the expressed needs. We also confirmed the resurgence of yaws in Cameroon through a survey among the pygmy population in the east region, and building on this, we have determined the status of yaws in 53 of 189 health districts and confirmed 37 of them as endemic for yaws.
Research conducted within the framework of this thesis, has increased our understanding of skin-NTDs, the efforts made in their control, and the challenges faced by the control activities in Cameroon. Based on these, we have recommended an integrated surveillance and control strategy of skin-NTDs to the National Control Programme. To the scientific community we recommend, accelerated research and development activities for point-of-care diagnostic tests, shorter treatment courses, and vaccines for reinforcement of prevention of these NTDs.