Epidemiology Bill Brieger | 17 Jul 2008 11:01 am
Malaria Dynamics – interactions with drugs and genes reported
The field of malaria research is dynamic. We are always learning new aspects about the disease and its interaction with the biological, social and economic environments. News stories today highlight two such interactions that have implications for public health beyond malaria control.
Reuters reports on Canadian researchers whose “surprising findings suggest that treating malaria with the cheap, widely used drug chloroquine — a close cousin of fluoroquinolones — may boost the risk of resistance to these antibiotics,” in South America. This resistance has even been found in remote villages where people have never even taken the antibiotics, fluoroquinolones.
As Davidson and colleagues note in PLoS One, It is not only a matter of chloroquine, but the some of replacement first line treatments, artimisinin-based combination therapies (ACTs) that contain a related drug like amodiaquine. We may be preventing death from malaria while boosting the chances of people not being able to control other diseases with cheap, available antibiotics.
Another interesting dynamic reported by the BBC is that, “A gene which apparently evolved to protect people from malaria increases their vulnerability to HIV infection by 40%.”The story points out an irony: “People of African descent have a variation of the “DARC” (Duffy antigen receptor for chemokines) gene which may interfere with their ability to fight HIV in its early stages. The Cell Host and Microbe study says the gene accounts for millions of extra HIV cases in sub-Saharan Africa.However, people with the gene appear to live longer with HIV than other.”
The scientific article on this dynamic, appearing in Cell Host and Microbe, and observed that, “The sum of the in vitro and genetic epidemiologic findings demonstrates that HIV might exploit DARC to its advantage: binding of HIV to DARC, a molecule that is expressed on one of the most abundant cell types (RBCs), might afford a unique biological niche that favors viral survival and persistence.”
The Weijing He and colleagues point out the need for further understanding of the dynamic among malaria, immune defenses, HIV and genetics: “Of broad interest, our studies underscore that DARC impacts on chemokines, malaria, and HIV, a ménage à trois. However, given the importance of the chemokine system in host defense, immune responses, and inflammation, it will be important to determine the contribution of DARC to the pathogenesis of other infectious disease and inflammatory disease states.” Ultimately we cannot address the problem of malaria without looking at the broader dynamics of infectious diseases and genetics in a given setting.