In an article published in Nature Communications in January of 2015, a connection was revealed between the presence of antibiotics in human blood and increased mosquito transmissibility of malaria. The apparent link, between the otherwise disparate concepts, lies in the effect of antibiotics on the gut flora of the Anopheles gambiae mosquito – the main vector involved in malaria transmission [1].
It is largely accepted that the use of antibiotics in humans can change the personal microbiome, including the makeup of gut flora. However, it has also been argued that these changes may be permanent [2]. Long-term antibiotic use has been shown to increase susceptibility to infections, such as Clostridium difficile [3], by way of changes or reductions in the good bacteria in our gut flora. The effects of antibiotics on human microbiomes has been significantly studied and considered. What has not been considered are the effects of human antibiotic use on disease vectors. The Nature Communications study by Gendrin et al. highlights the effects of a mosquito’s consumption of antibiotic-laced human blood [4].
The effects of human use of antibiotics is passed on to the mosquitoes that feed on our blood. Gendrin et al. found that a combination of penicillin and streptomycin added to the blood ingested by mosquitoes, disrupted their natural gut microbiome, just as it does in humans. The antibiotics actually increased the mosquitoes’ susceptibility to malaria infection. With these increased rates of mosquito infection comes increased malaria parasite transmissibility to humans [4].
The mosquitoes fed the antibiotic-laced blood also showed advantages akin to antibiotic use in livestock growth promotion – it raised the mosquitoes’ survival and procreation rates [1]. Altogether, areas where human antibiotic use are high (such as tuberculosis-endemic regions) may be at increasing malaria transmission risk.
In Africa, a child dies every minute from malaria and malaria-related complications [5]. Globally, malaria infects an estimated 198 million people and leads to approximately 600,000 deaths each year [5]. Malaria disease burden is localized to the developing tropical and subtropical climates. Although transmission used to occur in places like the southern United States and Europe, medical and public health infrastructure development has resulted in the elimination of the disease [6]. Approximately half of the global population live in regions where malaria transmission regularly occurs [7].
[1] http://www.nature.com/ncomms/2015/150106/ncomms6921/pdf/ncomms6921.pdf
[2] http://www.wired.com/2011/08/killing-beneficial-bacteria/
[3] http://www.mayoclinic.org/diseases-conditions/c-difficile/basics/causes/con-20029664
[5] http://www.who.int/mediacentre/factsheets/fs094/en/
[6] http://www.cdc.gov/malaria/about/distribution.html
[7] http://www.cdc.gov/malaria/about/facts.html
