Researchers at the University of North Dakota just published a study finding that Aedes vexans, a mosquito that is indigenous (native) to North America, is capable of becoming infected with the Zika virus and transmitting the virus through a bite. This is important news because Aedes vexans is the first North American mosquito confirmed as a transmitter of Zika.

Previously, we only knew that tropical mosquito species could transmit the virus. These tropical mosquitoes cannot survive in Northern climates such as ours, so experts have up until now considered us safe from likely disease sources. Now, however, we know that an indigenous mosquito may become infected. This raises the question: are we at risk of contracting the virus? Here’s what you should know about the possibility of Zika in Michigan, and what you can do about it.

Zika informational fact sheet

What Should I Know About Zika?

The Zika virus belongs to the same Flaviviridae family of viruses as dengue, the West Nile virus, and Japanese encephalitis. The virus spreads via arthropod vectors such as mosquitoes and ticks. Since its initial outbreak in 2015, Zika has spread throughout the Americas and to parts of Africa, Southeast Asia, and the South Pacific.

Most symptoms resulting from infection are usually mild in adults. They include fevers, headaches, nausea, fatigue, and joint pain, among others. Unfortunately, however, the virus is also strongly associated with Guillain-Barre Syndrome, an uncommon but serious sickness of the nervous system. Even worse, Zika transmits to children from pregnant mothers, and can cause serious birth defects and pregnancy problems, including microcephaly. Consequently, scientists consider Zika especially dangerous for pregnant women.

aedes vexans

What is Aedes vexans?

Aedes vexans is one of the most common mosquitoes in the world. It’s found on every continent except Antarctica and South America. It’s the most prevalent mosquito species in North America. The Aedes vexans species lays eggs in moist environments, usually on or near a source of standing water like a pool, puddle, or plumbing leak. They prefer moist, shaded environments where the soil stays wet for extended periods of time.

Contrary to popular belief, blood is not the primary food source of aedes vexans. They feed on nectar for sustenance. Blood gives females aedes vexans the protein required to lay eggs. Male aedes vexans don’t bite humans. Aedes vexan breeds and becomes most active in summer, because their eggs don’t usually hatch until the air temperature is at least 50 degrees. Though they can feed day or night, Aedes vexan becomes more active in the dark. They’re most prevalent at dusk.

map depicting possible spread of zika in US
source: https://www.cdc.gov/zika/vector/range.html

Are We At Greater Risk of Infection?

Not necessarily. According to Jefferson Vaughan, Ph. D., researcher and professor of arthropod-transmitted diseases at the University of North Dakota: “Just because a mosquito species is physiologically capable of transmitting a virus does not mean that that mosquito species is necessarily a dangerous vector.” A ‘vector’ is anything that can carry a disease and transmit it to another organism, such as a human being. As Dr. Vaughan notes, Zika is a primate virus. In order to contract it, the Aedes vexan would have to feed on an infected party twice. In addition, Aedes vexan mosquitoes feed on larger animals more frequently than they feed on humans.

It’s also important to remember that this study was just that: a study. Aedes vexan can transmit the virus in a controlled environment, but they haven’t transmitted the virus in nature, yet. There have been no reports of Zika infection of a human via contact with Aedes vexan to date. Vaughan and the other researchers at the U of ND suggest that more research will be required to define the Aedes vexans’ actual vector potential in North America.

Cases of symptomatic Zika virus in the US
source: https://www.cdc.gov/zika/reporting/2017-case-counts.html

How Common is Zika in the US?

As of May 17, 2017, the CDC reports no cases of symptomatic Zika virus in the US that were transmitted by local infected mosquitoes. All 119 symptomatic cases in the US occurred in travelers returning from infected areas abroad. It’s important to note, however, that evidence of a possible Zika virus infection was found in 1,845 pregnant women in US states. The Zika virus is a nationally notifiable condition, which means any doctor  will report any confirmed case to the CDC. 

According to the information we have right now, the following things would have to occur for a Michigan resident to contract the Zika virus without leaving the US:

  • A female Aedes vexan feeds on an unidentified carrier of the Zika virus in the US twice. This carrier could have contracted the disease abroad. The five identified carriers would not longer transmit the virus if fed upon.
  • That same Aedes vexan feeds on another person, transferring Zika carrier blood from the earlier feeding into the bloodstream of the newly bitten person.
  • The Zika virus develops from this contact.

Is this scenario impossible? No. Probable? Definitely not. As of January 2017, 220 people were infected with Zika in Florida and Texas. The CDC has issued specific travel considerations for pregnant women and other people at-risk of Zika infection. This study isn’t noteworthy because it poses an immediate threat, but because predictive models of Zika spread in the US did not account for Aedes vexan as a vector.  

mosquito net

What Should I Do?

Though we don’t believe you have any reason to panic, it never hurts to practice effective mosquito control. Take steps to prevent mosquito bites and make your home and property mosquito-proof. When you spend time outside this summer, apply bug spray at least once every two hours, and consider wearing long sleeves and pants, and boots with high socks. Cover your baby in protective clothing, too, and consider investing in mosquito nets for their crib, stroller, and baby carrier.

Other than practicing pest control in your own home, the best way to stay safe is to stay informed. Griffin will continue monitoring Zika developments and update you with any pertinent information, and you can also stay up-to-date by checking the CDC’s frequently updated Zika virus page.

 

If you’re concerned about a possible mosquito infestation on your property, remember that you can always call Griffin Pest Control. We can figure out why mosquitoes keep bothering you and stop them permanently. Stay safe and have a great summer!

 


Lancette, Josh. (2017, May 12). Study Finds Native North American Mosquito Can Transmit Zika [blog post]. Entomology Today. Retrieved from https://entomologytoday.org/2017/05/12/study-finds-native-north-american-mosquito-can-transmit-zika/

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