Zika FAQ’s

Zika Transmission

Where did Zika come from? How did it get here?

Zika virus was first discovered in 1947 in an infected monkey in Uganda. Zika was first isolated in a human in 1954 in Nigeria. There were few reported cases after 1954 until an outbreak in 2007 on the island of Yap in the South Pacific.

In early 2015 an outbreak began in Brazil. Because there is so much travel between the US and Latin America, and the mosquitoes that carry and transmit the virus live in the US, there is concern that Zika could spread throughout the US population. Currently there are no reported cases of Zika being transmitted by a mosquito in Baltimore. There have been four confirmed cases of mosquito-borne Zika in the US this summer

How long does the virus stay in the system?

The virus usually stays in a person’s blood for a week after infection. The virus has also been found in semen of an infected man who developed symptoms. The virus can persist in semen and vaginal fluid, however researchers are unsure how long the virus stays in other body fluids. 

How does the mother pass the virus on to the baby?

Scientists are not exactly sure how the mother passes the virus to her baby, but it is most likely that viral particles in the mother’s blood cross the placenta and infect the fetus.

Can you get HIV the same way that Zika is transmitted, by mosquito bites?

You cannot. When a mosquito bites an HIV positive person it digests the virus and destroys it. So when that same mosquito bites another person, it does not contain any virus to transmit in its saliva. Also, you cannot get HIV even if you kill a mosquito that has bitten an HIV positive person but not yet digested the virus, because there would not be a large enough amount of virus in the mosquito to infect you.

Does hand sanitizer help prevent Zika?

No, Zika is not spread by contact like shaking hands. Zika is spread by the bite of an infected mosquito, from an infected pregnant woman to her fetus, or through sex.

Can a woman sexually transmit the virus to her partner?

Yes. On July 15th there was the first confirmed case of a woman transmitting Zika to her partner through unprotected sex. 

Can Zika be transmitted to livestock or other animals?

At this time, animals do not appear to be involved in the spread of Zika virus.

There is no evidence that Zika virus is spread to people from contact with animals.

Zika and Pregnancy

If a woman is infected and recovers, is she still at risk of having a baby with microcephaly in future pregnancies?

To the best of our knowledge, previous infection will not affect future pregnancies.

For how long should I avoid getting pregnant after being infected with Zika?

Women should wait 8 weeks after symptoms first appeared to try and become pregnant. Men should wait 6 months after their symptoms appeared.

Will it affect women in the 2nd and 3rd trimesters of a pregnancy?

Yes, infection with the Zika virus during the second trimester of pregnancy can lead to microcephaly. There is some research that suggests that infection during the third trimester will not lead to microcephaly, but it is best to avoid travel to areas with Zika, mosquito bites, and practice safe-sex for the entire duration of the pregnancy.

Mosquito Control

Are the mosquitoes that carry Zika here in Maryland?

The Aedes aegypti mosquito responsible for the outbreak in Latin America has been seen in the Mid-Atlantic but is not common. Its close relative Aedes albopictus does live in Baltimore, and can transmit the virus.

Are there any infected mosquitos in Baltimore?

There are no confirmed cases of mosquito-transmitted Zika in Baltimore. 

Why don’t they just spray everywhere for the mosquitoes?

Although the mosquitoes that carry Zika virus are invasive, widespread spraying would kill native species that are helpful to the ecosystem and overuse of insecticides can lead to mosquitoes developing greater resistance to them. Furthermore, widespread spraying is not effective for reducing the populations for long periods of time. For this reason, and in accordance with CDC guidance, limited and targeted spraying is planned.

How far can the mosquitoes travel?

The mosquitoes that transmit Zika, the Aedes mosquitoes, travel about two blocks before they die.


Is DEET safe?

Yes. Use Environmental Protection Agency (EPA)-registered insect repellents with one of the following active ingredients: DEET, picaridin, IR3535, oil of lemon eucalyptus, or para-menthane-diol. Choosing an EPA-registered repellent ensures the EPA has evaluated the product for effectiveness. When used as directed, EPA-registered insect repellents are proven safe and effective, even for pregnant and breast-feeding women.

  • Always follow the product label instructions.
  • Reapply insect repellent as directed.
  • Do not spray repellent on the skin under clothing.
  • If you are also using sunscreen, apply sunscreen before applying insect repellent.

What other types of mosquito repellent are good to use?

Other brands that do not contain DEET use picaradin, oil of lemon eucalyptus or para-menthane-diol. Examples of these repellents include: Cutter Advanced, Skin So Soft Bug Guard Plus, Repel, Off! Botanicals (as opposed to Off!), Skin So Soft Bug Guard Plus Expedition, and SkinSmart.

Can mosquito repellent harm babies?

From the CDC: “Most repellents can be used on children aged more than 2 months. Protect infants aged less than 2 months from mosquitoes by using an infant carrier draped with mosquito netting with an elastic edge for a tight fit. Products containing OLE (oil of lemon eucalyptus) specify that they should not be used on children aged less than 3 years.”

What is para-menthane-diol?

Para-menthane-diol is a chemical extracted from the oil of the lemon eucalyptus plant that is used in many insect repellents. It has been shown to be as effective as DEET as a mosquito repellent.


If I have a compromised immune system, are my symptoms going to be more severe?

At this point, due to few reported cases, we do not know whether severe symptoms or complications occur more frequently in immunocompromised individuals. If you have a weaker immune system it is advisable to take extra precaution to avoid mosquito bites and practice safe-sex.

Do seniors have anything to worry about?

All humans are at risk to contract Zika. Everyone should take precautions to avoid getting bit by mosquitoes regardless of their age. Additionally, if you are sexually active and your partner(s) may have been exposed to the virus, you should follow the appropriate safe-sex guidelines. Because the elderly tend to have weaker immune systems, it is better to be extra cautious.

When will the vaccine for Zika be ready?

The most optimistic estimate for when a Zika vaccine could be ready is 2018. The National Institute of Allergy and Infectious Diseases will begin preliminary testing of vaccine safety in September, and depending on the results of those trials will do a larger study in early 2017. For the foreseeable future the best defense against the Zika virus will be mosquito control and safer-sex practices.

Will returning travelers be tested before being allowed back into the country?

No, travelers will not be tested before returning to the US. However, if a traveler starts to show symptoms of Zika virus they should talk to their doctor about being tested.

For the most updated version, check: http://health.baltimorecity.gov/zika-virus