Zika virus: New threat from tiger mosquito

In the group of viruses that includes dengue and chikungunya, a newcomer now has people talking about it. Also originating in Africa, zika was isolated in humans in the 1970s. Several years earlier, only a few human cases had been reported. It took until 2007 for the virus to show its epidemic capacity, with 5,000 cases in Micronesia in the Pacific, and then especially, at the end of 2013 in Polynesia, where 55,000 people were affected. In light of these recent events, researchers from IRD and the CIRMF in Gabon restarted work on the concomitant dengue and chikungunya epidemic that occurred in 2007 in the capital, Libreville, and which affected 20,000 people. Showing almost the same symptoms as its two dreaded cousins, did zika pass unnoticed by the researchers?

Climate, genetics can affect how long virus-carrying mosquitoes live

It's just math: The longer a mosquito lives, the better its odds of transmitting disease to humans or animals.

But as it turns out, factors such as the mosquito's own genetics and the climate it lives in have a big -- albeit complicated and not wholly understood -- role to play in its lifespan.
University of Florida researchers, hoping to better understand how West Nile virus affects mosquitoes, set up an experiment they outline in the Journal of Vector Ecology's current issue.
Mosquitoes can transmit any number of pathogens to humans, including protozoan malaria, West Nile, dengue and chikungunya viruses. Malaria cases range between 350 million and 500 million each year, with 1 million to 3 million deaths every year.
In the experiment, UF researchers examined survival rates for mosquitoes from two laboratory-reared colonies, one from Gainesville and one from Vero Beach.
Half of each of the mosquito colonies was fed West Nile virus-infected blood, the other half kept as a control population, and fed blood without the virus.
They divided the groups once more, this time keeping the mosquitoes at two temperatures, one group at 80.6 degrees, the other at 87.8 degrees Fahrenheit -- a rather large difference in temperature for cold-blooded insects.
Their findings were both unexpected and illuminating, said Barry Alto, a UF assistant professor of arbovirology based at the Florida Medical Entomology Laboratory in Vero Beach.

Gene differences in yellow fever, malaria mosquitoes mapped

Virginia Tech entomologists have developed a chromosome map for about half of the genome of the mosquito Aedes agypti, the major carrier of dengue fever and yellow fever.

With the map, researchers can compare the chromosome organization and evolution between this mosquito and the major carrier of malaria, the Anopheles gambiae mosquito, to find ways to prevent diseases.
"Despite looking somewhat similar, these mosquitoes diverged from each other about 150 million years ago. So, they are genetically further apart than humans and elephants," said Maria Sharakhova, a research scientist in the College of Agriculture and Life Sciences, a Fralin Life Science Institute affiliate, and the principal investigator of the study published in BMC Biologyand highlighted on Biome.

Mosquitoes reared in cooler temperatures have weaker immune systems

Urban epidemics resulting from viral diseases, such as West Nile fever and chikungunya fever, are transmitted by infected mosquitoes.

According to Virginia Tech scientists, mosquitoes reared in cooler temperatures have weaker immune systems, making them more susceptible to dangerous viruses and more likely to transmit them to people.
The connection between temperature and the mosquito's immune system, published May 31 in PLOS Neglected Tropical Diseases, is significant in light of global climate change, said researchers Kevin Myles and Zach Adelman, associate professors of entomology in the College of Agriculture and Life Sciences, and affiliates of the Fralin Life Science Institute.
"Our data offers a plausible hypothesis for how changes in weather influence the transmission of these diseases and will likely continue to do so in the future," Myles said.