Zika virus

Zika virus infection is a mild febrile viral illness transmitted by mosquitoes.

This information is intended for health professionals

For general information and advice about Zika virus, see Zika virus

About 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.

In 2015 and 2016, Zika virus outbreaks spread throughout the tropical and sub-tropical areas of the western hemisphere, as far north as Mexico, Florida 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 and elimination of any exotic mosquitoes.

You can find more information about mosquitoes on the Ministry of Health website and also tips on how to avoid mosquito bites while travelling.

Zika virus infection is notifiable in New Zealand as an arboviral disease.

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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 exception of pregnant women).

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.

Serious complications from Zika virus infection are uncommon.

However, based on research to date, there is scientific consensus that Zika virus is a cause of microcephaly and other severe fetal brain abnormalities as well as Guillain-Barré syndrome.

Zika virus pregnancy information for health professionals

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.

We know that Zika virus infection during pregnancy is a cause of congenital microcephaly and other severe brain abnormalities.

Zika virus has also been linked to other problems in pregnancies and among fetuses and infants infected before birth, such as miscarriage, stillbirth, and other birth defects.

A distinct pattern of birth defects, called congenital Zika syndrome, has emerged among fetuses and infants of women infected with Zika during pregnancy.

In addition to cognitive, sensory, and motor disabilities that are shared with other birth defects, congenital Zika syndrome is associated with five types of birth defects that are either not seen or occur rarely with other infections (eg, cytomegalovirus or rubella) during pregnancy:

severe microcephaly resulting in a partially collapsed skull
decreased brain tissue with brain damage (as indicated by a specific pattern of calcium deposits)
damage to the back of the eye with a specific pattern of scarring and increased pigment
limited range of joint motion, such as clubfoot
too much muscle tone restricting body movement soon after birth.

Therefore, the Ministry of Health recommends that women who are pregnant or plan to become pregnant in the near term should defer travel to areas with Zika virus present.

If travel is essential, if possible delay pregnancy if travelling to these areas.

If travelling in Zika-affected areas, women who are pregnant or plan to become pregnant should consult with their health care provider. All travelers should take all precautions to avoid mosquito bites, including the following:

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 eight 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.

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 serum) to 2 weeks (in urine) of the illness.

Testing whole blood is a suitable alternative to serum, particularly in investigations during the first 2 weeks. After the first 2 weeks, advice from an infectious disease specialist or microbiologist should inform any PCR testing.

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.

Additionally, on 5 May 2017 the CDC issued a Health Alert Notice (HAN) sharing evidence that IgM antibodies may stay in the body for months after the infection, making it difficult to determine if a positive IgM antibody test on a pregnant woman reflects a recent infection or one acquired before the pregnancy.

The HAN is available on the CDC website.

For these reasons, while a potentially valuable diagnostic tool Zika virus serology may be difficult to interpret and should involve a discussion with a microbiologist 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.

Sexual transmission of Zika virus

Zika virus is considered to be mainly spread by infected mosquitoes. However, there is growing information available about the risk of sexual transmission of Zika virus.

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, for at least six months after leaving a Zika-affected area.

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

Advice about avoiding sexual transmission of Zika virus can also be found on the following websites:

Monitoring Zika virus in New Zealand

Zika virus is one of a number of emerging infectious diseases which the Ministry of Health monitors on an ongoing basis.

The Ministry of Health has plans in place to manage infectious diseases.

However, it is important to note that the risk posed by Zika virus to New Zealand is extremely low as the mosquitoes that can spread Zika virus are not normally found here.

New Zealand has strong biosecurity and border health systems that prevent the establishment of mosquitoes that might transmit this disease, or others like dengue fever.