Zika Virus

Zika virus

Zika virus is a flavivirus, closely related to dengue. Cases of Zika virus have previously been reported in Africa, southern Asia and the Pacific Islands. Beginning in 2014, Zika virus outbreaks have occurred throughout the tropical and sub-tropical areas of the western hemisphere, as far north as Mexico and Puerto Rico.

Because Zika, dengue and chikungunya viruses are transmitted by mosquitoes mostly active during daytime, it's important that all travelers visiting affected areas continue to take protective measures to prevent mosquito bites throughout the day.  

Zika virus infection is symptomatic in only about 1 out of every 5 cases. When symptomatic, Zika infection usually presents as an influenza-like syndrome, often mistaken for other arboviral infections like dengue or chikungunya.

New Zealand currently has 15 mosquito species. The mosquito species (Aedes sp.) that are able to spread Zika virus are not normally found in New Zealand however they are found in many other countries around the world.

A national mosquito surveillance programme has been operating for some years at New Zealand's international points of entry (ports and airports). The ports and airports are monitored regularly throughout the year to ensure the early detection of any exotic mosquitoes.

On 1 February 2016 the World Health Organization (WHO) declared a Public Health Emergency of International Concern (PHEIC) regarding a recent cluster of microcephaly cases and other neurological disorders and the possible association of these illnesses with Zika virus infections. The WHO recommended efforts towards improved surveillance of and education regarding Zika virus as well as promotion of mosquito control. The WHO recommended no restrictions on travel or trade.

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Zika virus and pregnancy

• Related to Pregnancy

There are concerns that pregnant women who become infected with Zika virus can transmit the disease to their unborn babies, with potentially serious consequences. Reports from several countries, most notably Brazil, demonstrate an increase in severe fetal birth defects and poor pregnancy outcomes in babies whose mothers were infected with Zika virus while pregnant.

Additional international research is necessary and ongoing to determine the link between Zika virus and fetal damage.

Until more is known, the Ministry of Health recommends that women who are pregnant or plan to become pregnant in the near term consider delaying travel to areas with Zika virus present. If travel is essential, consider delaying pregnancy if travelling to these areas.

If travelling in Zika infected areas, women who are pregnant or plan to become pregnant should consult with their healthcare provider. All travelers should take all precautions to avoid mosquito bites, including:

• Wear long-sleeved shirts and long pants.
• Use insect repellents containing DEET, picaridin, oil of lemon eucalyptus (OLE), or IR3535. Always use as directed.
• Insect repellents containing DEET, picaridin, and IR3535 are safe for pregnant and breastfeeding women and children older than 2 months when used according to the product label. Oil of lemon eucalyptus products should not be used on children under 3 years of age.
• If you use both sunscreen and insect repellent, apply the sunscreen first and then the repellent.
• Use permethrin-treated clothing and gear (such as boots, pants, socks, and tents).
• Use bed nets as necessary.
• Stay and sleep in screened-in or air-conditioned rooms.
• Be particularly vigilant for the 2 hours after sunrise and the 2 hours before sunset.

We also advise that women who have travelled to an affected country without their partner use appropriate contraception for four weeks to avoid pregnancy. However, if the partner has also travelled to an affected country then see advice on sexual transmission of Zika virus.

If you are pregnant and develop a rash, red eyes, fever, or joint pain within 14 days of travel to a Zika virus infected country, please consult your health care provider and let them know your travel history.

This information will be updated as more research becomes available.

Sexual transmission of Zika virus

There is only limited information available about the risk of sexual transmission of Zika virus, but the risk is considered to be low when compared to the risk of transmission from infected mosquitoes.

Due to the potentially serious implications of transmitting Zika to a pregnant woman, we advise that:

• All men who have travelled to a Zika-affected area and have a pregnant partner should abstain from sexual activity (oral, vaginal, and anal) or use condoms for the duration of the pregnancy, whether they have symptoms or not.
• All men who have travelled to a Zika-affected area and have a partner who is at risk of becoming pregnant should abstain from sexual activity (oral, vaginal, and anal) or use condoms, whether they have symptoms or not. International advice about how long to abstain varies:
  • at least four weeks (WHO)
  • 3 months (Australian Department of Health)
  • 6 months (ECDC and Public Health England)
  • no specific duration mentioned (CDC).

We will continue to review New Zealand guidance as further information becomes available.

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Symptoms of Zika virus infection

• low-grade fever
• arthralgia, notably of small joints of hands and feet, with possible swollen joints
• myalgia
• headache, retro-ocular headaches
• conjunctivitis
• cutaneous maculopapular rash

Zika virus infection usually causes a mild disease (with the possible exception in pregnant women, as discussed below). However, as Zika infection may cause a rash that could be confused with diseases such as measles or dengue, these serious diseases do need to be ruled out. Diagnosis of Zika will first and foremost be based on symptoms, travel history and exclusion of other diseases including measles, rubella and dengue.

The incubation period is typically 3–12 days. There is no specific therapy for Zika virus infection and acute symptoms typically resolve within 4–7 days. Use paracetamol for pain and fever if needed. Until dengue can be ruled out do not take aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen, given the risk of bleeding.

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Laboratory testing

What types of testing for Zika virus are available to test pregnant women?

Reverse-transcriptase PCR (RT-PCR) can be used to detect the Zika virus during the first 1 week (in blood) to 4 weeks (in urine) of the illness. This RT-PCR test is currently performed in Wellington at ESR, Auckland at Labplus, and Christchurch at Canterbury Health Laboratories, with an expected turnaround time of 2 working days.

Serology is less reliable due to potential cross reaction with antibodies against other similar viruses (including dengue). This makes it difficult to differentiate Zika virus infection using antibody testing alone. For this reason, Zika virus serology is not recommended at this time as part of the algorithm for assessing pregnant women with a history of travel to areas with active Zika virus transmission. If Zika serology is being requested a discussion with a microbiologist needs to occur prior to testing.

Zika virus RT-PCR can also be performed on amniotic fluid although it is not currently known how sensitive or specific this test is for congenital infection. The likelihood of an infected fetus developing a fetal abnormality is not known at this time