WHAT IS ZIKA VIRUS AND HOW DOES IT SPREAD?
Zika virus (ZIKV) was first discovered in 1947 in the Zika Forest of Uganda. Shortly thereafter, it was isolated from mosquitoes and then humans in 1968. ZIKV is a flavivirus similar to yellow fever, dengue, Japanese encephalitis, and West Nile virus. Prior to 2007, it had only been detected in central Africa and throughout southeast Asia. However, in 2007, it was associated with a disease outbreak on Yap Island in the south Pacific, representing the first time it had spread outside of
Asia. From there, it spread to South America with human cases first reported in 2014. Zika is a virus transmitted by the bite of the mosquito to humans and from human to human. Only 1 in 5 people infected with Zika will show symptoms. Zika has been linked to microcephaly in babies who contracted the virus from their mothers while pregnant. The CDC is also investigating a correlation of Zika with Guillain-Barré syndrome, an uncommon sickness of the nervous system.
ZIKV is transmitted by Aedes mosquitoes. In the Americas, it has only been linked to transmission by Aedes aegypti. Ae. aegypti is also responsible for the transmission of dengue virus, yellow fever virus,
and chikungunya virus. Recently in Africa, the virus was detected in Aedes albopictus, or the Asian tiger mosquito; hence, it is likely that Ae. albopictus could vector the virus in the Americas.
SYMPTOMS OF ZIKA INFECTION
- Typically, people with ZIKV infection begin showing symptoms with a mild headache.
- Within a day or two, a maculopapular rash may appear and can cover many parts of the body (arms, hands, face, and chest).
- Following the rash, people generally report continued fever, malaise, and body aches.
- Other symptoms can include diarrhea, constipation, abdominal pain, and dizziness.
TREATMENT OF ZIKA INFECTION
- Treatment includes rest and the use of acetaminophen to relieve fever.
- Patients should also be advised to drink plenty of fluids if diagnosed.
- If anyone has recently traveled to a known endemic area and are displaying any of the symptoms of Zika infection, they should consult their physician immediately.
MORE ABOUT AEDES AEGYPTI
Ae. aegypti, the yellow fever mosquito, is characterized by a silvery-white “lyre-shaped” pattern of scales on its body. It is a peridomestic species found not far from human dwellings, and is particularly abundant in towns and cities. They are primarily early morning or late afternoon feeders, but females can also take a bloodmeal at night under artificial illumination. Aedes aegypti is reported to fly only a few hundred yards from breeding sites. Larvae can be found in a variety of artificial containers, including buckets, tires, cans, and flower pots.
ZIKA AND AEDES AEGYPTI IN THE UNITED STATES
As of February 2016, most US cases were imported from travelers who contracted the virus in other countries and returned to the US while infected. One of the factors accelerating spread of Zika virus throughout the Americas could be that it does not appear to require an animal reservoir host, like West Nile virus. In other words, non-infected mosquitoes are able to acquire the virus after feeding directly on infected humans. In essence, there is no “middle man” in the endemic cycle of ZIKA, allowing it to spread rapidly where abundant, competent vector mosquitoes and humans are present together.
UNITED STATES AREAS OF RISK:
A portion of the United States is at the highest risk because of climate and the presence of Aedes mosquitoes. Both Ae. aegypti and Ae. albopictus are limited in their distribution in the US. Therefore, it is unlikely that ZIKV will become a disease that circulates in the local mosquito populations throughout the US like West Nile virus, but select areas of the US are at high risk. Please refer to the figure to the right for a map depicting each mosquito’s US distribution.
SHOULD YOU BE CONCERNED ABOUT ZIKA?
Are you in a risk zone?
Aedes species are not everywhere. There are two species, Aedes aegypti and Aedes albopictus that to the best of current knowledge are the only species capable of actively vectoring, or transmitting, the Zika virus.
Humans are reservoirs and can transmit Zika.
This bears repeating. With nearly all other mosquito borne viruses humans are ‘dead end’ hosts, and do not transmit the virus. Not the case with Zika. If infected with Zika, people can transmit Zika four ways:
o Sexual transmission from a man to a woman
o Blood transfusion
o In utero from an infected mother to fetus
o To biting female mosquitoes
The human cases you have read about in the U.S. to date have all been ‘imported’ travel cases, i.e. the individual had traveled to South America, was bitten there and became symptomatic once returning to the states.
Not your West Nile mosquitoes
- Both Aedes aegypti and Aedes albopictus like to lay eggs in very small amounts of water. That's how they earned their ‘container breeder’ nickname -- you can find their eggs in items as small as a bottle cap. They love standing water, therefore any type of container is a potential breeding site, e.g. trays of flower pots, bird baths, standing water in gutters, downspout drains, rain barrels, still ponds, junk piles.
- They like to live in residential areas and bite during the day. . . just the opposite of the night-biting mosquitoes that can carry West Nile Virus.
- In fact, Aedes aegypti prefer to rest inside at night. Leave your garage door up? That’s a wide open invitation to Ae. aegypti. carports, sheds and other out buildings are all desired resting spots too.
Everyone Needs to Fight Zika Together.
If you live in an area where Aedes aegypti or Aedes albopictus are found, you need to do your part to keep your property free of potential breeding sites. Remember – these species like to lay eggs in as little as a teaspoon of water and can hatch in just 3 to 4 days. More importantly, the Aedes mosquitoes breed in your yard generally stay near your yard – reducing spots helps protect your family.
Be Zika free, check every three.
Every three days, residents should check their yards for potential breeding sites.
Tip and toss water found in:
- Flower pot trays
- Planter boxes
- Bird baths
- Kiddie pools
- Sandbox and yard toys
- Wheel barrows
- Watering cans
Remove trash or junk from yard that can hold water:
- Abandoned tires
- Trash / Trash Cans
- Unused lawn furniture or grills
- Food containers
Check gutters and drain tubes (especially ridged tubing)
Treat rain barrels with a larvicide from hardware store or nursery