Antibiotic-filled blood supercharges mosquitoes

Antibiotic-filled blood supercharges mosquitoes

By Ryan Whitwam Jan. 15, 2015 9:48 am mosquito

Malaria is one of the most pressing public health concerns in tropical and subtropical parts of the world. While diseases like ebola grab headlines on occasion, malaria kills hundreds of thousands of people every year, and new research indicates the use of antibiotics could actually worsen the problem. A series of experiments conducted at Imperial College London show that mosquitoes fed antibiotic-laced blood lived longer, had more offspring, and were more able to better transmit malaria.

Malaria is a disease, not an organism. The organism that causes malaria is a parasitic protozoan in the Plasmodium family. There are a number of different species of Plasmodium that can cause malaria, but most serious human infections are caused by P. falciparum. A protozoan is a single celled organism, but it’s much larger and more complex than bacteria, which are treated with antibiotics. They are eukaryotic, meaning the structure of the cells is more like that of an animal cell with organelles and a nucleus containing the genetic material. The Amoeba is another example of a protozoan.

There’s no reason to expect malaria parasites to be susceptible to antibiotics in the same way bacteria are, but to actually see increased transmission from antibiotic exposure is unexpected. There are a small number of antibiotic compounds that also treat malaria, but the mechanism is different. Plasmodium has an incredibly complex life cycle once it’s in a human host, but it gets there by way of a female Anopheles mosquito. This is where exposure to antibiotics affects malaria, but it may be an indirect benefit to the parasite.

The researchers fed mosquitoes blood samples from malaria-infected children. Half the samples were doped with a penicillin-streptomycin antibiotic cocktail, while the others had a control solution added. The insects fed antibiotic-infused blood were more likely to pick up the malaria parasite. What’s more, they had statistically significant increases in lifespan and reproductive success.

These antibiotics are often administered to treat bacterial infections unrelated to malaria, so it’s possible they’d be in the bloodstream of someone bitten by a mosquito in real life. The researchers theorize that the presence of antibiotics is affecting the gut bacteria of mosquitoes, essentially killing off enough of the naturally occurring organisms that malaria parasites can more easily take root.

We see similar effects in humans on antibiotics — the disruption of your normal gut bacteria can open you up to dangerous infections because of reduced competition for space. You actually have more bacterial cells in your digestive tract than human cells in your entire body, and if the safe ones aren’t taking up the space, other less friendly visitors will move in. It’s the same for mosquitoes apparently.

These findings suggest that areas of the world where antibiotics are used more frequently to treat infections (or are overused) could actually be exacerbating the spread of malaria. Antibiotic use can be reduced, but these are still important drugs with many valid use cases. The safest course of action is to continue combating the spread of malaria through control of mosquito populations.

Leave a Reply