Objective: To investigate the possible impact of soil-transmitted helminth (STH) infection on malaria severity, level of parasitaemia and clearance/reduction of Plasmodium parasites following treatment with anti-malarial drugs.
Methods: 458 voluntary malaria patients who visited the Alaba Kulito Health Center, southern Ethiopia, for medical treatment in November and December 2007 were included in this study. Giemsa-stained thick and thin blood films were used for the determination of parasitaemia and identification of Plasmodium species, respectively. Stool sample was collected from these patients and diagnosed for intestinal helminths using Kato-Katz technique. Haemoglobin concentration was measured using a portable spectrophotometer (HemoCue HB 201). Malaria parasite clearance was checked on day 3 post-treatment.
Findings: The prevalence of co-infection of malaria with the major soil-transmitted helminths (STHs), i.e., with hookworm species, Ascaris lumbricoides and Trichuris trichiura was 9.6%, 6.3% and 2.1%, respectively. About 8.1% of the study subjects had severe malaria. Intensity of hookworm infection showed positive association with malaria parasite densities (F=3.510, P=0.033). STHs infection in general was negatively correlated with the symptoms of severe malaria (OR=0.317, 95% CI=0.315-0.86, P=0.01), but a small proportion (4.5%) of malaria patients who were concurrently harboring one or more intestinal helminths had severe malaria. Only few malaria patients (2.3%) co-infected with STHs were found positive for Plasmodium parasites on day 3 post-treatment.
Conclusion: The present findings indicate that soil-transmitted helminths have very little contribution to malaria severity in co-infected individuals. The findings also indicate that STHs do not have significant impact on clearance rate of Plasmodium falciparum and Plasmodium vivax when treated with anti-malarial drugs.