Association of Schistosoma Haematobium Infection With Protection Against Acute Plasmodium Falciparum Malaria in Malian Children

Abstract

Plasmodium falciparum and Schistosoma haematobium are co-endemic parasitic diseases with worldwide distribution. Evidence suggests interactions occur between helminthic and malaria infections, although it is unclear whether this effect is beneficial or harmful to the host. Malian children 4-14 years of age with asymptomatic S. haematobium infection (SP) (n = 338) were prospectively matched by age, sex, and residence to children without schistosomiasis (SN) (n = 338) who were cleared of occult intestinal parasites, and followed-up for one malaria transmission season (25 weeks). The time to the first clinical malaria infection, incidence of malaria episodes, and parasitemia were recorded. Age associated protection from malaria in children with schistosomiasis was observed. SP children (4-8 years of age) compared with SN children demonstrated delayed time to first clinical malaria infection (74 versus 59 days; P = 0.04), fewer numbers of malaria episodes (1.55 versus 1.81 infections; P = 0.03) and lower geometric mean parasite densities (6,359 versus 9,874 asexual forms/mm(3); P = 0.07) at first infection. No association between schistosomiasis and P. falciparum malaria was observed in children 9-14 years of age. We conclude that underlying schistosomiasis is associated with protection against clinical falciparum malaria in an age-dependent manner.

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

“…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. 8,9 In contrast, other studies suggested an additive or synergistic effect of coinfection.…”

“…7 Another study among children in Mali in [2002][2003] with both an epidemiological and a biological approach, showed an age-dependent protection in children infected with urinary schistosomiasis against acute P. falciparum malaria. 8,9 However, other studies suggested an additive or synergic effect of coinfection, 10,11 as for example, Wilson and others 11 who showed that concurrent chronic exposure to Schistosoma mansoni and P. falciparum could have a synergistic effect on childhood morbidity.…”

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

“…In contrast, previous study demonstrated an agespecific protective effect of Schistosoma hematobium infection following the acquisition of uncomplicated P. falciparum malaria (Lyke et al 2005). Children with schistosomiasis have less severe malaria, their first clinical symptoms are delayed and parasitaemia is reduced.…”

Associations Between Helminth Infections, Plasmodium falciparum Parasite Carriage and Antibody Responses to Sexual and Asexual Stage Malarial Antigens

“…; however, this has not been consistent. For example, the prevalence and severity of malaria as well as Plasmodium falciparum parasitemia density has been reported to be higher 3,4 in some but lower 5,6 in other studies comparing helminth-infected subjects with those uninfected. Similarly, at the immunological level, there are conflicting reports regarding the effect of chronic helminth infections on the immune responses to Plasmodium spp.…”