There are currently no vaccines for prevention, although they are in development. Zika purified inactivated virus (ZPIV) vaccine, an investigational vaccine, has started clinical trials to test safety and efficacy in the US.
Primary prevention currently relies on mosquito bite prevention and mosquito population control (e.g., removing or modifying breeding sites), as well as the prevention of non-vector transmission (e.g., sexual, transfusion, nosocomial).
Mosquito bite prevention and population control
Wearing clothes that cover as much of the body as possible (e.g., long-sleeved shirts and long trousers); clothes may be treated with permethrin
Staying in places with air conditioning or that use window and door screens to keep mosquitoes outside
Sleeping under a mosquito net (possibly impregnated with insecticide)
Using approved insect repellent (if ≥2 months of age); DEET, picaridin, and IR3535 can be safely used in pregnant and breastfeeding women when used as directed
Covering cribs, strollers, or baby carriers with a mosquito net
Emptying, cleaning, or covering containers that can hold water to reduce areas where mosquitoes can breed including in and around households.
The main way to prevent congenital Zika virus infection is to prevent maternal infection using mosquito bite prevention measures.
Travellers returning from areas of ongoing transmission should use mosquito bite prevention measures for 3 weeks after returning to prevent spread to uninfected mosquitoes.
During outbreaks, insecticide spraying (using an insecticide recommended by the WHO) may be carried out.
The development of Aedes aegypti mosquitoes that are resistant to arbovirus infection is a preventive approach that shows promise. The US Food and Drug Administration (FDA) has released a report concluding that a field trial of genetically modified mosquitoes would pose no significant environmental impact in Key Haven, Florida; however, further regulatory requirements are needed before these mosquitoes are approved for commercial use.
Prevention of sexual transmission
Recommendations for pregnant couples: the CDC recommends that pregnant women with male or female sex partners who live in or have travelled to an area with active transmission should abstain from sex (vaginal, anal, oral) or use barriers against infection (e.g., condoms) during sex for the duration of the pregnancy. Additionally, the CDC recommends that pregnant women talk with their healthcare providers about their sex partner’s potential exposures to Zika virus and symptoms of Zika-like illness.
Recommendations for non-pregnant couples: the CDC recommends that if only the female partner travels to an area with risk for transmission, the couple should use condoms and abstain from sex for at least 2 months after the female partner's symptom onset (if symptomatic) or last possible exposure (if asymptomatic). However, if the male partner (or both partners) travel to an area with risk for transmission, the couple should use condoms and abstain from sex for at least 3 months after the male partner's symptom onset (if symptomatic) or last possible exposure (if asymptomatic).
The WHO still recommends safe sex practices for at least 6 months in men or women returning from areas with active transmission, regardless of whether they are symptomatic or asymptomatic.
Healthcare providers should discuss reproductive life plans (including intention of pregnancy and timing of pregnancy) with women of reproductive age in the context of the potential risks associated with Zika virus infection.
Women living in endemic areas should consult local health authorities for advice before becoming pregnant.
Family planning services, including access to contraception to prevent unplanned pregnancy, is important to prevent Zika-related congenital abnormalities. Access to adequate contraception may be an issue in some countries.
In Brazil, there are no formal recommendations to avoid pregnancy because of the Zika virus outbreak; the choice to get pregnant is regarded as a personal decision.
Prevention while travelling
Advice varies internationally and travellers should stay informed about Zika virus outbreaks.
The WHO recommends that pregnant women should not travel to areas of ongoing transmission.
The CDC recommends that pregnant women should not travel to any area where there is a risk of Zika virus infection, including:
Areas where the virus has been newly introduced or re-introduced and local transmission is ongoing
Areas where the virus was endemic (present before 2015) and there is no evidence that transmission has stopped
Areas where the virus is likely to be circulating but has not been documented.
To help pregnant women and others identify areas of Zika risk, the CDC has produced an interactive map that allows people to search for location-specific information and travel recommendations.
Mosquito bite and sexual transmission prevention measures are recommended when travelling to areas of ongoing transmission.
Prevention of transfusion transmission
The FDA recommends universal testing of donated whole blood and blood components for Zika virus in the US and its territories.
The FDA recommends that people should defer donating blood if they have been to areas with ongoing Zika virus transmission, have potentially been exposed to the virus, or have confirmed infection. In areas without active transmission, donors at risk for infection (e.g., those who have had symptoms suggestive of infection, those who have had sexual contact with a person who has resided in/travelled to an area with active transmission in the prior 3 months, and those who have travelled to areas with ongoing transmission in the past 4 weeks) should defer donating blood for 4 weeks. People with a history of Zika virus infection should not donate blood for 120 days after a positive viral test or the resolution of symptoms (whichever is longer).
Patients who develop symptoms within 14 days of giving blood should notify the place of donation.
An investigational test is available to screen blood donations.
Prevention of nosocomial transmission
Transmission in a healthcare setting has not been described as yet; however, standard precautions (e.g., hand hygiene, use of personal protective equipment, respiratory hygiene and cough etiquette, safe injection practices, safe handling of potentially contaminated equipment or surfaces) are recommended for the protection of healthcare professionals and patients in healthcare settings and labour and delivery settings. These precautions are recommended regardless of whether the infection is suspected or confirmed.
The CDC has produced interim guidance for the management of healthcare personnel with occupational exposure. There is currently no post-exposure prophylaxis or vaccination available.
People infected with Zika virus should be protected from further mosquito exposure during the first week of illness (i.e., the viraemic stage) to prevent other mosquitoes from becoming infected and therefore reduce the risk of local transmission.
Zika virus infection (and Zika virus congenital infection) is a notifiable disease in many countries. Healthcare providers should report suspected and confirmed cases to their state or local health department. In the US, these departments should report laboratory-confirmed cases to the Centers for Disease Control and Prevention (CDC) through Arbonet. In other countries, cases should be reported to the relevant national public health authorities who are then encouraged to inform the World Health Organization (WHO) and Pan American Health Organization (PAHO) through established International Health Regulations (IHR) channels.
The WHO has produced reporting requirements for cases of Zika virus infection, microcephaly, and Guillain-Barre syndrome:
However, the definitions for surveillance reporting areas were updated in March 2017:
The CDC has started a US-based Zika pregnancy registry. The data collected through the registry will be used to update clinical recommendations and improve prevention of infection during pregnancy.
The Puerto Rico Department of Health and CDC have developed a surveillance system to evaluate the association between Zika virus infection during pregnancy and adverse outcomes during pregnancy, birth, and early childhood (up to 3 years of age) called the Zika Active Pregnancy Surveillance System (ZAPSS).
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