Recently, a virus transmitted by mosquitoes, known as Zika, has had its first known case diagnosed in the United States. Health officials in Dallas, Texas reported that a person who had sex with someone who had traveled from Venezuela contracted the Zika virus infection. This virus has previously been found in much of the Southern Hemisphere of Africa, Asia, and South America. It has also been found in Central America.

The Zika virus is transmitted by several common species of the Aedes mosquito. These mosquito species are also found throughout the World and include much of the United States. The Aedes genus of mosquito is also one that can spread Dengue or chikungunya viruses. The mosquitoes that spread Zika virus typically are active and bite during the daytime, which makes it important to remember to wear repellent even if you’re not going to be out at dusk or nighttime. Mosquitoes become infected when they feed on a person already infected with the virus. Infected mosquitoes can then spread the virus to other people through bites.

Zika Virus Infection Symptoms

About 20% of people who are infected with Zika virus will show symptoms. From the Center for Disease Control and Prevention (CDC), symptoms of Zika virus can include:

  • Fever
  • Rash
  • Joint pain
  • Conjunctivitis (red eyes)
  • Other symptoms may include: muscle pain, headache, pain behind the eyes, and/or vomiting

Usage of the Zika Virus Infection Calculator can assist in diagnosing Zika virus in patients. 

Infections from this virus typically cause non-specific flu-like symptoms mentioned above and often last less than a week. There have been reported links to Zika virus infection and Guillain-Barre Syndrome.  Of significant importance, Zika virus infection in pregnant women, may also lead to birth defects.

Zika Virus and Microcephaly

Zika virus is linked to a potential severe birth defect called microcephaly.  This condition causes incomplete brain development in babies at the time of birth. This can lead to developmental delays, learning disorders, seizures, or other medical problems later in life. The link between Zika virus and cases of microcephaly were found when cases of microcephaly increased from a few hundred to several thousand cases in Brazil, one of the areas with the highest incidence of the mosquito-borne Zika virus. The link between Zika virus and microcephaly was found when the virus was discovered in the amniotic fluid of women who gave birth to babies with microcephaly. Women who are pregnant, especially those who have traveled recently, and have symptoms like those above should seek medical attention by their OB/GYN or local primary physician.

Physicians can use the Congenital Zika Virus Infection – Evaluating for Zika Virus Embryopathy to evaluate pregnant women at risk. 

As of Feb. 3rd, 2016, the CDC has advised women who are pregnant to avoid travel to countries where Zika virus has been found (list below). Additionally, women who are planning on becoming pregnant or may become pregnant should take caution while traveling to these countries.

In response to the recent case of acquired Zika virus in Texas through sexual intercourse, the CDC has issued interim guidelines urging women who are pregnant to abstain from sexual relations or use condoms every time with a male partner, if the partner has traveled to or lives in an area with active Zika virus transmission.

The CDC has advised against travel to several countries where Zika virus is prevalent:

  • Barbados
  • Bolivia
  • Brazil
  • Cape Verde
  • Colombia
  • Curacao
  • The Dominican Republic
  • Ecuador
  • El Salvador
  • French Guiana
  • Guadeloupe
  • Guatemala
  • Guyana
  • Haiti
  • Honduras
  • Jamaica
  • Martinique
  • Mexico
  • Panama
  • Paraguay
  • Saint Martin
  • Samoa
  • St. Martin
  • Suriname
  • U.S. Virgin Islands
  • Venezuela
  • Puerto Rico

Zika Virus Prevention

The prevention of mosquito bites is the most important way to prevent illness and spread of the virus. It is recommended to wear long sleeve shirts and pants when possible if mosquito exposure is likely. Also, the CDC recommends the use of insect repellents registered with the United States Environmental Protection Agency to protect yourself and your family from mosquito bites.

Recommended mosquito repellents are those that contain one of the following: DEET, picaridin, IR3535, and some oil of lemon eucalyptus and para-menthane-diol products that can provide long lasting protection. Examples of insect repellant products and other tips for avoiding mosquito bites.

Travelers, especially pregnant women, to countries where Zika virus is found, including recently, Puerto Rico, should travel with caution and take steps to prevent mosquito bites.

Homeowners should be vigilant about checking around their property for areas that can enable mosquitoes to breed easily. These mosquitoes typically lay eggs in and near standing water in things like tires, buckets, bowls, bird baths, flower pots, and vases.  If you have these items around your home, it is imperative to remove the standing water and clean them regularly. These mosquitoes are aggressive daytime biters and prefer to bite people. They live indoors and outdoors near people. If sunscreen is applied to exposed skin, mosquito repellent should be applied after the sunscreen to maintain effectiveness.

Persons with non-specific flu-like symptoms, especially in returning travelers should seek medical attention from their primary care physician. There is no specific treatment for the virus and no vaccine exists to prevent it. Infected individuals are encouraged to rest and drink plenty of liquids to prevent dehydration.

In addition to Zika virus, there are several other mosquito-borne illnesses that can be acquired from an infected mosquito. The symptoms and diagnostic criteria, including workup for each of these arboviruses can be found online, or through the iOS or Android app.

Dengue Fever

  • Criteria for the Diagnosis of Dengue FeverCriteria for the Diagnosis of Dengue Fever
  • World Health Organization Case Definition for Dengue FeverWorld Health Organization Case Definition for Dengue Fever

Chikungunya Fever

  • Clinical Features of Chikungunya FeverClinical Features of Chikungunya Fever

West Nile Virus

  • Risk Factors for Severe West Nile Virus DiseaseRisk Factors for Severe West Nile Virus Disease