Scimex: French and Senegalese researchers have found the culprit responsible for a spree of an 'unknown origin fever' - a bacterium, Rickettsia felis, which appears to be transmitted by mosquitoes. That's surprising because mosquitoes are not known for transmitting bacterial infections, and this bug is generally transmitted by fleas - including in Australia. But these fever outbreaks have occurred in known malarial areas in sub-Saharan Africa, suggesting mozzies are the guilty party.
Some mosquitoes that transmit malaria might also be capable of transmitting a pathogenic bacterium, according to a study. Rickettsia felis
is a bacterium recently implicated as a human pathogen, particularly in
patients diagnosed with "fever of unknown origin" in sub-Saharan
Africa. The bacterium can be transmitted by fleas, but it is unknown if
there are other possible modes of transmission. Given that human R. felis
infections have been prevalent in malaria-endemic regions, Philippe
Parola and colleagues explored the possibility that the mosquito Anopheles gambiae, which transmits malaria, can also transmit R. felis. The authors fed mosquitoes on either blood or cellular media, both infected with R. felis, and found R. felis DNA in the mosquitoes' tissues for up to 2 weeks after feeding. R. felis
DNA was also found on the cotton used to feed the mosquitoes after
infection, suggesting that the mosquitoes could transmit bacteria
through saliva when biting. The authors observed bacteria in the
salivary glands of infected mosquitoes, as well as in mosquito ovaries,
although the mosquitoes did not transmit the infection to their
offspring. Notably, when infected mosquitoes fed on healthy mice, the
mice developed transient infections. The findings suggest that A. gambiae mosquitoes could potentially transmit R. felis in the wild.