Mosquitos and Zika

Mosquitos and Zika

Map showing the potential range of A. aegypti the mosquito that can transmit Zika virus
Map showing the potential range of A. aegypti the mosquito that can transmit Zika virus

4 Things to Know about Zika Virus

Drs. Jody Green and Jonathan Larson; Nebraska Extension

There has been a lot of media coverage recently focused on the seemingly new and terrifying illness known as the Zika virus. While Zika appears to have minimal impacts on adult humans, if a pregnant woman becomes infected, her fetus may suffer from developmental abnormalities such as microcephaly. Unfortunately, there has been a lot of confusion and misinformation springing up around this disease, so here are some facts to help you better understand this complicated issue.

4. Zika has been known since 1947

While it seems like Zika appeared out of nowhere, truthfully it’s been known about since 1947. Scientists working in Uganda first identified this disease in some monkeys. By 1952 it had been found in humans in both Uganda and the Democratic Republic of Congo.  Between then and 2007, only 14 cases were documented of humans with Zika virus, though the symptoms (fever, rash, joint pain, and conjunctivitis) are so general that some cases may have gone undiagnosed. Following these initial reports in Africa Zika has been found in Asia, the Americas, and some Pacific islands.

3. The mosquito that transmits Zika isn’t in Nebraska

The main mosquito that transmits Zika is the yellow fever mosquito, Aedes aegypti. This species, when infected, can transmit dengue, chikungunya, and yellow fever. Their geographical range is mostly tropical, subtropical, and temperate climates, and their natural range does not include Nebraska (Figure 1). This summer, some counties in the state will be trapping for mosquitoes and monitoring for the presence of the mosquito that could carry Zika.

Although we are not on high alert for Zika, Nebraskans do need to prevent bites from the Culex mosquitoes that carry and transmit West Nile virus. These mosquitoes acquire West Nile from infected birds and transmit it to humans via saliva when they feed with their piercing-sucking mouthparts. The number of cases, as well as deaths have been tracked and recorded by the Nebraska Department of Health & Human Services since 2002. People infected with West Nile virus may show no symptoms; some may suffer mild flu-like symptoms, and less than 1% of cases will develop a serious illness. There are no medications to treat or vaccines at this time to prevent the West Nile virus infection.

 

So to recap:

  • Not all mosquitoes transmit the Zika virus.
  • The mosquitoes that transmit Zika do not live in Nebraska.
  • Mosquitoes in Nebraska can transmit West Nile Virus.

 

2. You can prevent and control mosquitoes in your yard

The best way to avoid any pathogens transmitted by mosquitoes is to prevent being bitten. Like any pest management program, IPM is the strategy that works best to prevent mosquito bites at home in the yard. Sanitation is a must to eliminate breeding sites and harborage locations of mosquitoes. Female mosquitoes lay eggs on the surface of standing water and the larvae (“wigglers”) require water to survive before pupation. Removal of stagnant water in a variety of containers such as flowerpots, buckets, gutters, pool covers, used tires, and dog bowls will break the mosquito life cycle. A general rule is to dump any water that has been standing for more than five days.  

Culex mosquitoes are active biters in the evening, so it is important to wear long sleeves and pants or permethrin-treated clothing when outdoors between dusk and dawn. The effective insect repellents applied to skin include those with the active ingredients: DEET, picaridin, or the oil of lemon eucalyptus.

As far as chemical control, Mosquito Dunks® (Figure 2) contain the active ingredient bacterium, Bacillus thurengiensis israelensis (Bti), which is toxic to mosquito larvae when consumed, but non-toxic to humans, pets, pollinators, fish, and other wildlife. They are sold in hardware stores, and will dissolve in standing water such as water troughs, fishponds, rain barrels, and birdbaths. They are effective immediately and can last for a month.

We do not recommend the use of foggers or adulticide treatments by homeowners.

 

1. There have been no cases that originated in the continental US

In the United States and its associated territories we have seen cases of local transmission in American Samoa, Puerto Rico, and the US Virgin Islands. Outside of those areas though, the only cases to be found involve travelers that have recently visited South America. This is extremely good news, but we do need to keep an eye on the situation. If these infected individuals were to run into the mosquito capable of transmitting the disease we could begin to see local spread here in the US. Luckily, the federal government is implementing a new budget to help discover Zika in the US and to prevent its spread.

If you want to learn more about Zika virus, its transmission, or efforts to control it, then check out the CDC or the World Health Organization for more information:

http://www.cdc.gov/zika/

http://www.who.int/mediacentre/factsheets/zika/en/

Mosquito dunks, a popular and safe method of controlling immature mosquitoes.
Mosquito dunks, a popular and safe method of controlling immature mosquitoes.
Image of Jonathan Larson
Jonathan Larson
Extension Educator - Entomology

Jonathan Larson is the Nebraska Extension entomologist for Douglas and Sarpy counties. His main focus is lawn and landscape pests but he also helps with bed bugs, roaches, and any other home invader that has six or more legs. Jonathan has his Bachelor of Science in Entomology from Purdue University, and his Ph.D. in Entomology from the University of Kentucky.

Contact Jonathan at:
Douglas/Sarpy County Extension
8015 W Center Rd.
Omaha, NE 68124-3175
(402) 444-7804