The influence of host haematocrit on the blood feeding success of Anopheles stephensi: implications for enhanced malaria transmission

Abstract

Two studies were carried out to determine the effect of the rodent malaria Plasmodium yoelii nigeriensis on the blood feeding success of Anopheles stephensi. Initially, pairs of mice with similar packed cell volume (PCV) (measured by haematocrit) were selected. Following infection of one of the pair its PCV gradually fell. At various times post-infection, a comparison was made of the bloodmeal size (haemoglobin content) of mosquitoes feeding on these mice. The bloodmeal sizes increased with parasite-induced fall in PCV down to a haematocrit of 43-44%, which occurred approximately 48 h post-infection. Bloodmeals were significantly reduced, however, when mosquitoes fed on mice with higher parasitaemias and a haematocrit of 15-35%. Thus, at early stages of infection, mosquitoes ingested a bloodmeal significantly greater than did the mosquitoes feeding on the control mice. However, mosquitoes were not able to compensate for severe infection-associated anaemia. To compensate for variation due to innate differences in the mice, a second experiment was performed. Mosquitoes were fed on the same mice before (control) and after infection. Again, the bloodmeal size increased with decreasing PCV down to haematocrits of 42-45%, but declined thereafter. In this host-parasite-vector system, haematocrits that maximized erythrocyte intake were produced when gametocytes, capable of exflagellation, were present.

Evaluation of the Antimalarial Potential of Streptomyces Sp.

“…Based on this classification, the extract of S. griseus exhibited a good antiplasmodial activity. Anemia, hypoglycemia, body weight loss, and body temperature reduction are the general features of malaria-infected mice body weight loss is one feature of rodent malaria infections [29]. The result of the present work, however, showed only a statistically nonsignificant slight gain in body weight of crude extract administered of P. berghei infected mice.…”

Effect of Crude Leaf Extract of Bauhinia strychnifolia in BALB/c Mice Infected with Plasmodium berghei

“…The influence of malaria on hematological parameters is extensively investigated and PCV reduction is considered a hallmark of both human and rodent malaria [24,28]. Infected mice may suffer from severe anemia because of rapid erythrocyte destruction, either by parasitemia or spleen reticulo endothelial cells [29]. For instance, in one study it was noted that within an estimated 48 h of post-infection rodent PCV was depleted to 43-44%.…”

Olfaction in vector-host interactions

“…Early in infection, when PCV has only dropped 1-3%, mosquitoes allowed to feed on anaesthetised infected mice were able to imbibe significantly larger amounts of haemoglobin (a proxy measurement for red blood cells) than mosquitoes feeding on control mice. However, as parasitaemia increased and PCV fell below 6% of the control mice the haemoglobin taken by mosquitoes feeding on infected mice was significantly reduced (Taylor and Hurd 2001). Thus, initially, the predicted decrease in viscosity as PCV falls appears to enhance erythrocyte uptake.…”