Abstract:
Background: Anopheles gambiae s.l. and An. funestus are important vectors of malaria and
bancroftian filariasis, which occur as co-endemic infections along the Kenyan Coast. However, little
is known about the occurrence and prevalence of concomitant infections of the two diseases in
mosquito and human populations in these areas. This study reports the prevalence of concomitant
infections of Plasmodium falciparum and Wuchereria bancrofti in mosquito and human populations in
Jilore and Shakahola villages in Malindi, Kenya.
Methods: Mosquitoes were sampled inside houses by pyrethrum spray sheet collection (PSC)
while blood samples were collected by finger prick technique at the end of entomological survey.
Results: A total of 1,979 female Anopheles mosquitoes comprising of 1,919 Anopheles gambiae s.l
and 60 An. funestus were collected. Concomitant infections of P. falciparum sporozoites and filarial
worms occurred in 1.1% and 1.6% of An. gambiae s.l collected in Jilore and Shakahola villages
respectively. Wuchereria-infected mosquitoes had higher sporozoite rates compared to noninfected
mosquitoes, but multiple infections appeared to reduce mosquito survivorship making
transmission of such infections rare. None of the persons examined in Shakahola (n = 107) had
coinfections of the two parasites, whereas in Jilore (n = 94), out of the 4.3% of individuals
harbouring both parasites, 1.2% had P. falciparum gametocytes and microfilariae and could
potentially infect the mosquito with both parasites simultaneously.
Conclusion: Concerted efforts should be made to integrate the control of malaria and bancroftian
filariasis in areas where they co-exist.
