This past year has been quite a year for mosquitoes. Besides just being a pest at almost any kind of outdoor activity, there is one more pathogen that has been added to the list of pathogens that mosquitoes can transmit: Zika virus. Since the increase in microcephaly cases that were caused by Zika virus in Brazil, there has been a great deal of funding to scientific studies investigating the effects of Zika virus on hosts and also understanding more about the transmission and ecology of Zika. During early investigations into Zika, two major players were identified in the transmission of Zika virus, the mosquitoes Aedes aegypti (yellow fever mosquito) and Aedes albopictus (Asian tiger mosquito).
Both mosquito species occur in the United States, so although Zika is not established, it is possible that it could become established in the future. There are two big questions that strike me when I think of this: 1) how long until Zika is established in the United States? 2) What can we do, if anything, to prevent or prolong the establishment of Zika? To discover answers to these questions involves, among other things, applying what we know about other viruses that are similar, such as chikungunya virus, as well as what we know about the ecology of the primary vectors (or transmitters) of Zika.
Aedes aegypti (yellow fever mosquito) was the first found that can carry Zika virus in the wild and has been determined to be the primary vector. Although Aedes albopictus (Asian tiger mosquito) has also been found to carry Zika, it is not considered to be the primary vector mostly because it is more of a generalist, feeding on many different animals, not just humans like Aedes aegypti. Also, Aedes aegypti lives in areas near humans, and also likes being indoors resting on walls, under beds, etc.; whereas, Aedes albopictus lives in more rural areas encountering humans less often. In terms of range, Aedes albopictus has a larger potential range because it can survive in cooler temperatures than Aedes aegypti, meaning that Aedes albopictus might be a more important vector species in more temperate regions. Both of these species feed during the day and sometimes during the night.
So, what can we do now to help prevent Zika from establishing or as least prolong how long it will take? The biggest things we can do is prevent mosquito bites by preventing encounters with mosquitoes. When preparing for outdoor events or activities wear long sleeves (making it difficult for them to reach your skin to bite), apply insect repellent, treat clothing with repellent, or use insect repellent candles. If there is standing water somewhere in your yard, make sure to dump it so that these mosquitoes cannot reproduce. Another way to reduce encounters with mosquitoes, is to mosquito-proof the house. Because Aedes aegypti in particular likes to rest in houses, it is helpful to have screens on every window and screen door. If sleeping in buildings without screens or sleeping outside, make sure to use a mosquito net to prevent bites at night. People can also reduce the amount of time they spend outdoors during the day, when these mosquitoes primarily feed.
Although these recommendations seem trivial, they can make a big difference in regard to transmission of pathogens. The less likely mosquitoes are to encounter a host, the less likely the pathogen they carry can be transmitted. There are other efforts underway to reduce populations of mosquitoes that transmit pathogens. Locally, spraying of insecticides is being done in areas with standing water. Researchers are taking several approaches to determine ways to decrease populations of mosquitoes that transmit pathogens. All of these efforts together can help to prevent establishment of Zika and also decrease transmission of other pathogens such as chikungunya virus and dengue virus, as well as other pathogens transmitted by other species of mosquito such as West Nile Virus.