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Background: Parasitic worms evade immune responses, and interactions between diseases can cause altered immunologic outcomes compared to what usually occurs with single infections. These interactions may influence vaccine and chemotherapeutic efficacy. Schistosoma mansoni and Plasmodium falciparum are co-endemic in Uganda and are the leading parasitic causes of public health problems across sub-Saharan Africa. Plasmodium falciparum is the major causative agent of malaria and Schistosoma mansoni is one of the causative agents of intestinal schistosomiasis. Objectives: The overall aim was therefore, to elucidate the impact of the comorbidity on protective T helper immune responses on P. falciparum and S. mansoni co-infection. Methodology: This study evaluated the T helper immune responses in individuals with independent S. mansoni infection, independent P. falciparum infection, co-infection and non-infection in school attending children in a co-endemic area along Lake Victoria shores, Uganda. Immune responses were categorized into Th1, Th2, and Th17 based on unique cytokine(s) produced by the T helper subpopulation in ex vivo. Kato Katz thick smears and circulating cathodic antigen tests were performed for S. mansoni screening, whereas thick and thin blood smear techniques were performed for P. falciparum screening. Results: We observed an up regulated Th1 T helper subpopulation in independent P. falciparum infections compared to the uninfected group. Suboptimal T helper immune responses were detected in independent S. mansoni infection characterized by significantly down regulated Th1 (Z = −1.425, p = 0.0313) response in comparison to the non-infected group. Suboptimal T helper immune responses were also recorded in the co-infected individuals characterized by significantly down regulated Th1 (Z = −3.260, p = 0.0273) and Th2 (Z = −1.180, p = 0.0078) responses compared to independent P. falciparum. Conclusions: S. mansoni infection is a major contributor of a reduced effective T helper immune response against P. falciparum in P. falciparum and S. mansoni co-infection.

Background: Parasitic worms evade immune responses, and interactions between diseases can cause altered immunologic outcomes compared to what usually occurs with single infections. These interactions may influence vaccine and chemotherapeutic efficacy. Schistosoma mansoni and Plasmodium falciparum are co-endemic in Uganda and are the leading parasitic causes of public health problems across sub-Saharan Africa. Objectives: The overall aim was therefore, to elucidate the impact of S. mansoni infection on protective T helper immune responses on P. falciparum and S. mansoni co-infection. Methodology: This study evaluated the T helper immune responses in individuals with independent S. mansoni infection, independent P. falciparum infection, co-infection and non-infection in school attending children in a co-endemic area along Lake Victoria shores, Uganda. Immune responses were categorized into Th1, Th2, and Th17 based on unique cytokine(s) produced by the T helper subpopulation in ex vivo. Kato Katz thick smears and circulating cathodic antigen tests were performed for S. mansoni screening, whereas thick and thin blood smear techniques were performed for P. falciparum screening. Results: We observed an up regulated Th1 T helper subpopulation in independent P. falciparum infections compared to the uninfected group. Suboptimal T helper immune responses were detected in independent S. mansoni infections characterized by significantly down regulated Th1 (Z = -1.425, p = 0.0313) response in comparison to the non-infected group. Suboptimal T helper immune responses were also recorded in the co-infected individuals characterized by significantly down regulated Th1 (Z = -3.260, p = 0.0273) and Th2 (Z = -1.180, p = 0.0078) responses compared to independent P. falciparum. Conclusions: S. mansoni infection is a major contributor of a reduced effective T helper immune response against P. falciparum in P. falciparum and S. mansoni co-infection.

Major control efforts over many decades have resulted in a substantial reduction in the prevalence of schistosomiasis japonica in the People’s Republic of China, although pockets of new infection continue to arise, particularly in the mountainous areas of the south. As well, the completion of the Three Gorges Dam, which crosses the Yangtze River and other large irrigation projects underway, may have significant environmental and ecological impacts likely resulting in expansion of the habitats for the intermediate snail host Oncomelania hupensis in some areas, thereby increasing the risk of human and bovine infection, and resulting in potentially new challenging consequences for control. The epidemiological picture for China will be briefly summarised and the current effective control strategies highlighted. The situation in the Philippines will also be briefly outlined but the picture is far less encouraging as there is limited national funding for schistosomiasis control; since the termination of the World Bank Loan program for schistosomiasis control in the late 1990’s, both schistosome prevalence and the associated morbidity have rebounded to former levels. Some results of recent surveillance studies we have undertaken in the Philippines will be described which indicate that schistosomiasis japonica is now far more prevalent, both in humans and bovines, than has been appreciated. Results of a large intervention trial we have completed in China - in the highly endemic Dongting Lake area downstream of the Three Gorges Dam, aimed at field-testing integrated strategies, including the use of a bovine transmission blocking vaccine, for schistosomiasis control, will be presented. The results of the trial in China will provide parameters for mathematical modelling of future control methods so as to define the long-term impact and cost-effectiveness of integrated control measures for both China and the Philippines. We believe that such an integrated approach, incorporating bovine vaccination, can lead to the future elimination of schistosomiasis from China.