Malaria and obesity: obese mice are resistant to cerebral malaria

Background: The relationship between malaria and obesity are largely unknown. This is partly due to the fact that malaria occurs mainly in tropical areas where, until recently, obesity was not prevalent. It now appears, however, that obesity is emerging as a problem in developing countries. To investigate the possible role of obesity on the host-parasite response to malarial infection, this study applied a murine model, which uses the existence of genetically well characterized obese mice. Methods: The receptivity of obese homozygous ob/ob mice was compared to the receptivity of control heterozygous ob/(+) lean mice after a single injection of Plasmodium berghei ANKA sporozoites. Both parasitaemia and mortality in response to infection were recorded. Results: The control mice developed the expected rapid neurological syndromes associated with the ANKA strain, leading to death after six days, in absence of high parasitaemia. The obese mice, on the other hand, did not develop cerebral malaria and responded with increasing parasitaemia, which produced severe anemia leading to death 18-25 days after injection. Conclusion: The observed major differences in outward symptoms for malarial infection in obese versus control mice indicate a link between obesity and resistance to the infection which could be addressed by malariologists studying human malaria.