The Nasty Aegypti Mosquito

Many of us have heard about the Zika Virus on the news, but might not understand how serious it is, especially those who live in the NW states. I recently took an updated nursing course on the subject and I was amazed at what this little bugger can cause. The potential for a localized outbreak of the Zika Virus in the USA is significant given the level of travel exposure, opportunities of migration, and the prevalence of mosquitoes along the southern rim of the country. As of December 2016, cases of the Zika Virus within the USA have been reported in returning travelers and in women having intimate sexual contact with men infected while traveling to regions with ongoing mosquito transmission. Zika has migrated out of Africa and Asia into the Americas over the past two decades.

Primarily, the Zika Virus is often asymptomatic. However, infection during pregnancy is often complicated by transmission of the virus to the developing fetus. The results are arrested neurological development, microcephaly, and related congenital anomalies. There is also evidence linking the Zika infection with post-infectious Guillain-Barre syndrome. Guillain-Barre is an acute, progressive syndrome characterized by flaccid paralysis and often triggered by infection. Most patients recover after many weeks, but often require respiratory ventilation support and management of complications. Microcephaly is a rare pediatric disorder in which the growth of the fetal brain size is unexpectedly small for a given stage of development. Zika is characterized by headache, conjunctivitis, a pruritic rash, mild weakness, and mild fever, lasting three to six days. In the course of acute infection during pregnancy, the virus can be transmitted across the placenta to the developing fetus.

In the past, the aegypti mosquito thrived on nonhuman hosts. It has adapted to an urban habitat and shows a preference for the human host over mammals. It flourishes in impoverished crowded areas without piped water, inadequate trash disposal, and ineffective barrier protections such as screen doors. A single female deposits its eggs at multiple sites. It takes advantage of stagnant water sources, pet bowls, cemetery vases, and tires. Adult mosquitoes of both sexes feed on nectar and fruit. Females require blood protein to fully develop their eggs. Only the female bites. The aegypti mosquito is an aggressive daytime biting mosquito and feeds in the hours of dawn and dusk. They are stealth feeders and approach their victims from behind and bites on ankles and elbows. This mosquito is a sip feeder in that it bites multiple humans in the course of its blood meal. The female prefers shady areas for rest and is adept at hiding under beds and in closets to later emerge for a nocturnal feed. Of public concern is if this vicious feeder emerges with a second vector with a potential for widespread outbreak in other parts of the country.

The full spectrum by which Zika is transmitted sexually is not yet known. It has been detected in saliva, urine, semen, and breast milk. Studies are underway to determine the incidence, duration, and pattern of virus shedding in men with and without symptomatic Zika infection. For now, the CDC recommends that men diagnosed with Zika consider using condoms or abstaining from sex for six months following the infection. There isn’t any effective antiviral therapy as of yet for the Zika infection. The general recommendations for pregnant women in the USA are:

  • all pregnant women should be assessed for possible Zika Virus exposure at each prenatal visit
  • Advised not to travel to an area active with Zika
  • If the pregnant woman must travel, follow strict steps to avoid mosquito bites and prevent sexual transmission during the trip
  • Have partner use condoms or other barrier methods to prevent infection during the woman’s pregnancy
  • cover exposed areas of skin by wearing long-sleeved shirts and pants
  • use insect repellents registered with the EPA and contains DEET, or oil of lemon eucalyptus. Sleep in screened areas and air-conditioned rooms
  • use mosquito netting over strollers, carriers, and cribs of infants younger than two months of age.

Virologists anticipate it will take several years to bring a Zika vaccine to implementation.

 

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