Helminth and Plasmodium infections are common in the tropics. In-utero exposure to these infections may influence susceptibility to childhood malaria.
In a trial of anthelminthic treatment in Uganda, 2,345 mother-child pairs were followed up. Pregnant women were randomized to receive albendazole or placebo, and praziquantel or placebo. Children were randomized to receive albendazole or placebo from age 15 months to five years. Maternal Plasmodium and helminth infection status was determined during pregnancy. Childhood malaria data was collected prospectively from birth to age five years. We investigated (i) the association between maternal helminth and Plasmodium infections in pregnancy and childhood malaria, and (ii) the effect of deworming in pregnancy and early childhood on childhood malaria.
Common maternal infections were hookworm (45%), Mansonella perstans (21%), Schistosoma mansoni (18%), and Plasmodium falciparum (11%). Childhood helminth infections included Trichuris trichiura (8.3%), Ascaris lumbricoides (4.3%), S. mansoni (2.9%) and hookworm (2.1%). At age five years, 69% of the children were still under follow-up. The incidence of malaria was 34 episodes per 100 child-years.
Maternal hookworm infection was associated with an increased rate of childhood clinical malaria, and increased odds of child asymptomatic malaria. Children infected with T. trichiura (aHR, 1.89 (95% CI, 1.05-3.42)), A. lumbricoides (aHR, 4.33 (95% CI, 1.53-12.30)), and hookworm (aHR, 3.25 (95% CI, 1.08-9.77)) at age four years had an increased rate of clinical malaria in the fifth year of life compared to the uninfected. Similarly, at age five years, children infected with these helminths were more likely to have asymptomatic P. falciparum parasitaemia compared to the uninfected.
Maternal anthelminthic treatment in pregnancy effectively treated maternal helminth infections but had no effect on malaria in the offspring. Child quarterly albendazole provided a beneficial effect for clinical and asymptomatic malaria, and this effect was strongest in the second year of life. Moreover, the effect of albendazole on childhood clinical malaria was modified by child helminth infections (P for interaction = 0.02).
This is the first report of an association between helminth infections in pregnancy and malaria in the offspring, and of a beneficial effect of albendazole treatment on childhood malaria. Our findings highlight the need to understand further the interactions between Plasmodium and helminth infections in pregnancy and childhood, in an effort to improve malaria and helminth control strategies.