Epidemiology and control of polyparasitism with schistosomiasis, soil-transmitted helminths and Taenia solium infections in rural and co-endemic areas of the Democratic Republic of Congo

Over a quarter of the world’s population is infected with helminth parasites; many of which are long-lived and cause chronic infections. Schistosomiasis, soil-transmitted helminths (STH) and Taenia solium infections belong to the neglected tropical diseases (NTDs) and are common in rural and poor urban settings of sub-Saharan Africa [1]. STH and Schistosoma spp. cause long-term chronic morbidity including anemia and iron-deficiency [2–4], malnutrition and impaired child growth and cognition [5,6]. In addition, Schistosoma spp. infections may cause liver and urogenital tissue damage [7]. Taenia solium-related morbidity is strongly associated with neurocysticercosis, a major cause of epilepsy and various neurological disorders within endemic regions [8,9]. Geographic distributions of these parasitic worms overlap in many endemic territories. Moreover, they share transmission routes, risk factors, risk groups and/or within-host habitats. Consequently, concomitant infections with multiple parasite species can occur in the human host, with a high potential to interact and to result in common morbidities. Nevertheless, most studies have so far focused on single helminth parasite infections, and little is known about the distribution and determinants of co-infections in human populations and the consequences for control. Helminth co-infections may alter disease epidemiology and severity, and the feasibility and efficacy of drug treatment, while in turn, anthelminthic drugs for one infection may alter the course and severity of the other infections and diseases. This presents both challenges and opportunities for helminth control in co-endemic areas as well as for current integrated control programs that target multiple infections at once by combined mass drug administration (MDA) [10–14].
The Democratic Republic of Congo (DRC) is estimated to have the second or third highest number of cases of schistosomiasis and STH infections in sub-Saharan Africa [1], but there is an overall paucity of data supporting this statement [15]. The country is also reported to be endemic for T. solium, though data are scarce [16]. In 2012, the Ministry of Health adopted a national plan against neglected tropical diseases, including the mass distribution of anthelminthics (MDA) in endemic regions [17]. However, implementation of this strategy is just starting. Recent surveys conducted in some villages of Kimpese health district (in Bas-Congo province) point to co-endemicity of schistosomiasis, STH and T. solium infections in that area. Respectively, 32.1% and 56% of schistosomiasis and STH infections were found among school aged children from 14 schools [18] and a T. solium cysticercosis prevalence of 21% was reported in one village community [19]. However, up-to-date published data about helminth (co-)infections in DRC are scarce, let alone about the resulting interactions and (co)morbidities, and the consequences for control.

Keywords:B780-tropical-medicine