Schistosomiasis co‐infection in humans influences inflammatory markers in uncomplicated Plasmodium falciparum malaria

Abstract

Malaria and schistosomiasis are the two major parasite diseases present in developing countries. The epidemiological co-infection with schistosomiasis could influence the development of the physiological reaction associated with Plasmodium falciparum infection in human. Most studies have demonstrated the association of circulating levels of interferon-gamma (IFN-gamma), tumour necrosis factor-a (TNF-alpha), interleukin-10 (IL-10), transforming growth factor (TGF-beta) and soluble Tumour Necrosis Factor Receptors (sTNF-RI and sTNF-RII) with the morbidity of malaria. In the present study, we showed that Schistosoma haematobium co-infection influences, in an age-dependent manner, the unbalance between pro- and anti-inflammatory circulating cytokines that play a key role during malaria infection. Indeed, children co-infected by S. haematobium have higher levels of IFN-gamma and sTNF-RII than children infected only by P. falciparum. In contrast, co-infected adults presented a significant increase of IFN-gamma, IL-10, TGF-beta, sTNF-RI and sTNF-RII rates and IL-10/TNF-alpha ratio. Taken together, this study indicates that schistosomiasis co-infection can unbalance the regulation of inflammatory factors in uncomplicated P. falciparum malaria. The possible consequences of the schistosomiasis co-infection for age-dependent malaria morbidity are discussed.

Coinfection with Plasmodium falciparum and Schistosoma haematobium: Additional Evidence of the Protective Effect of Schistosomiasis on Malaria in Senegalese Children

“…[4][5][6]17 In this study, we focused on the interaction between schistosomiasis and malaria infection. Several biological studies have shown a synergistic effect of coinfection, 16,[18][19][20][21] whereas other studies suggested an acceleration or regulation toward protective profile of the acquired immunity against malaria in children coinfected with malaria and schistosomiasis 9,22 and another study did not find an association. 23 A study on children conducted in Mali in 2002-2003 presented both epidemiological and biological approaches and concluded on a protective effect of infection with urinary schistosomiasis on malaria.…”

“…9,22,[27][28][29][30] As to the two antagonistic responses (Th1 and Th2) described in animals and humans, it has been established that the immune response caused by helminth infections is predominantly Th2, leading to a Th1 downregulation and to an exacerbation of Th2-dependent antibody response, which would accelerate the process of parasite clearance, and favor P. falciparum elimination with a better control of malaria parasite density. 22 A recent study on malaria-urinary schistosomiasis coinfection, conducted in Senegal, showed that children presenting moderate intensity of urinary schistosomiasis infection produced higher IgG1 and IgG3 responses to whole P. falciparum extracts than children not infected with urinary schistosomiasis. 18 Interestingly, IgG1 and IgG3 isotypes are known to be involved in the malaria protective immune response.…”

Reduced protective effect of Plasmodium berghei immunization by concurrent Schistosoma mansoni infection

“…The influence of schistosomes in the acquisition of immunity against Plasmodium has been proposed in several field studies (Diallo et al 2004, Sokhna et al 2004, Mutapi et al 2007). However, the actual findings are controversial as epidemiological observations suggest a range of scenarios in which helminth infections may not only increase the susceptibility to Plasmodium infections, but also protect against severe malaria under certain circumstances (reviewed in Nacher 2004, Brooker et al 2007, Nacher 2008.…”

Protective Effect of Chronic Schistosomiasis in Baboons Coinfected with Schistosoma mansoni and Plasmodium knowlesi

“…This immunoregulation does not appear to have impaired the ability of animals to clear parasites but may have attenuated some malaria-associated pathology, such as reduced immune-mediated RBC lysis of uninfected erythrocytes. Studies in Senegal, Ghana, and elsewhere have suggested a more anti-inflammatory environment in groups protected from severe malaria (24,(61)(62)(63)(64)(65). Thus, an early proinflammatory response may be important in controlling parasitemia.…”

“…Results in human studies have also been conflicting. Some studies have shown that helminth infections protect against malaria-associated morbidity (12-17), while others indicate that coinfections enhance clinical malaria (18)(19)(20)(21)(22) or have no influence on malaria outcome (23,24). A number of factors can contribute to differing results, such as parasite exposure (large single or repeated smaller infections), age, the duration of prior infections, and the methods of data collection and analysis (25).…”