Abstract:
Background: Necator americanus (hookworm) and Plasmodium falciparum co-infections are common in endemic
communities in rural Ghana. Human immune responses to P. falciparum and hookworm are complex, and the
dynamics of cytokine levels and effector mediators are poorly understood. This study aimed to determine the
effect of hookworm and P. falciparum co-infection on parasite intensities and cytokine profiles in individuals
before and after deworming drug treatment.
Methods: In this cross-sectional study conducted in the Kintampo North Municipality of Ghana blood and stool
samples were analyzed from 984 participants (aged 4–88 years). Stool samples were collected at baseline from
all participants and examined for the presence of hookworm using the Kato-Katz method. Blood and stool
samples were analysed again two weeks after albendazole treatment of hookworm infected individuals. Malaria
parasitaemia was estimated by light microscopy and P. falciparum-specific 18S rRNA gene PCR method used for
species identification. Serum levels of circulating cytokines interleukins -5, -10 (IL-5, IL-10), tumor necrosis
factor [TNF]-α, and eotaxin [CCL11] were determined using ELISA based methods.
Results: Malaria parasitaemia was significantly reduced in hookworm and P. falciparum co-infected individuals
(p = 0.0018) while hookworm intensity was similar between groups. IL-10 level was significantly higher in the
co-infected individuals (39.9 ± 12.2 pg/ml) compared to the single infected or the uninfected group
(10.7 ± 7.6 mg/ml). IL-5 level was higher in the hookworm only infected individual. TNF-α levels were higher
in all infected groups compared to the uninfected controls. CCL11 levels were significantly higher in subjects
infected with hookworm only or co-infected with hookworm and P. falciparum. There was a significantly ne-
gative correlation (rs = −0.39, p = 0.021) between hookworm eggs per gram of stool and CCL11 levels in the
group mono-infected with hookworm which was not affected by treatment. Treatment with albendazole led to a
significant reduction of TNF-α (p = 0.041), IL-5 (p = 0.01) and IL-10 (p = 0.001) levels.
Conclusion: This study shows that in the absence of other helminths, co-infection of hookworm with P. falci-
parum may modulate blood parasitemia levels and cytokine responses. Data also show that deworming drug
treatment alters these cytokine profiles in hookworm infected subjects. Future studies to elucidate the potential
mechanisms underlying these observations should include an assessment of parasite specific cellular responses.
