Schistosomiasis in school-age children in Burkina Faso after a decade of preventive chemotherapy
Ouedraogo H, et al. Bulletin of the World Health Organization
2016; 94: 37–45. doi: http://dx.doi.org/10.2471/BLT.15.161885
[Full article can be accessed at http://www.who.int/bulletin/volumes/94/1/15-161885/en/]
Human schistosomiasis is endemic in 78 countries. In 2013, nearly 240 million people in Africa were at risk of infection and required preventive chemotherapy. Several endemic countries in Africa launched national programs for the control of schistosomiasis following the World Health Assembly resolution in 2001. Programs focus on preventive chemotherapy with praziquantel and are targeted at school-age children and at-risk adults through mass drug administration (MDA) programs. Burkina Faso established a national program for the control of schistosomiasis and soil-transmitted helminths in 2004, with the main objective to use mass administration of praziquantel to prevent human schistosomiasis. In 2007, this program was integrated into a national integrated program against neglected tropical diseases. By 2013, four and five rounds of praziquantel MDA was conducted in the meso-endemic and hyper-endemic zones, respectively. In 2013, a survey was conducted at 22 sentinel sites across schistosomiasis-endemic areas of the country to determine the impact of MDA conducted and to assist in planning.
The survey was conducted by the national monitoring and evaluation team, following required ethics approval processes in-country. At the 22 sentinel sites, stool and urine samples were collected to check for schistosome eggs of Schistosoma mansoni
and S. haematobium
among 3514 school children by the Kato-Katz and urine filtration methods. Data from 2013 were compared with summary data from the 2004 published baseline data and the 2008 assessments at the same 22 sites, as the raw data were not available. In general, intensity of infection was compared based on the arithmetic mean egg counts for all subjects. Children were considered to have heavy S. haematobium
infections if they had at least 50 eggs per 10 ml of urine. Children with more than 399 eggs per gram of faeces were considered to have heavy S. mansoni
infections. Prevalence and intensity of infection were compared using χ2 and Kruskal–Wallis tests, respectively.
Of the 3514 school children observed, 287 children (adjusted prevalence 8.76%) were detected with S. haematobium
infection, with a range from 0.0% to 56.3%. Prevalence of S. haematobium
was significantly higher in Boucle du Mouhoun, Centre-Est, and Sahel, compared to eight other regions. S. mansoni
was only detected in two regions, Centre-Sud (0.31%) and Hauts Bassins (8.75%). The adjusted arithmetic mean intensity of S. haematobium
infection, among all children, was 6.0 eggs per 10 ml urine. Less than 1% of the children in six regions had heavy S. haematobium
infections. According to the impact assessment data conducted in the 22 sentinel sites, the prevalence of S. haematobium
was considerably higher in 2008 compared to 2013. Overall, the prevalence and intensity of S. haematobium
infection declined remarkably between 2004 and 2013. Within the integrated program for the control of neglected tropical diseases, the cost, including drug transportation and distribution, supervision during the distribution, training of drug distributors, and social mobilization, of a round of MDA with praziquantel was estimated to be US$ 0.08 per person treated using the 2013-2014 MDA data.
Discussion and Comments
Burkina Faso has made progress in the control of schistosomiasis at a modest cost since the program began. According to World Health Organization (WHO) criteria, 8 regions had eliminated urogenital schistosomiasis as a public health problem, and three other regions had reached the target of controlling the morbidity caused by schistosomiasis through preventive chemotherapy. The data indicate that regular treatment with praziquantel can prevent schistosomiasis morbidity and can lead to elimination of schistosomiasis in certain transmission settings.
It was however noted that, some sentinel sites showed similar or higher prevalence in 2013 as compared to 2008. Possible causes for an increase in the prevalence of infection are: frequency of treatment may not be adequate, inadequate focal treatment coverage, or social or environmental factors that support transmission despite the benefits of preventive chemotherapy, among others.
Following the results of the assessment, the national program reviewed the achieved progress and set objectives for the next phase of the program. The objectives will use MDA: (i) biennially, to interrupt the transmission of S. haematobium
and S. mansoni
in the Cascades, Centre, Centre-Nord, Centre-Ouest, Centre-Sud, Nord, Plateau Central and Sud-Ouest regions; (ii) annually, to control schistosome related morbidity or eliminate schistosomiasis as a public health problem in the Boucle du Mouhoun, Est, Hauts Bassins and Sahel regions; and (iii) biannually, to control schistosome-related morbidity or eliminate schistosomiasis as a public health problem in the Centre-Est region.
Overall, apart from increasing treatment, other public health interventions may need to be added such as water and sanitation hygiene, health education, snail management, and operational research on mollusciciding. Behavioral change communication will also need to be supported in order to change water-contact behavior to minimize the risk of infection in the future.