With the Rio Olympics kicking off, the SMC gathered background information on the Zika virus to aid in any reporting during the Games.
Here is a Q&A with local experts, please feel free to use any of these comments in your reporting.
Professor Michael Baker, Professor of Public Health, University of Otago
What are the symptoms of Zika infection in most people – is it different in pregnant women or people with suppressed immune systems?
“Most Zika infections cause no symptoms. About 20% of people develop a mild ‘flu-like’ illness with fever, joint pains, and red eyes. The incubation period is usually 3–12 days.”
How long does it last and how long do people normally take to recover?
“For the minority of people who develop a clinical illness, symptoms generally last 4-7 days.”
What are the risks of developing a serious side-effect, such as Guillain-Barré syndrome? What is GBS and what effects does it have in sufferers?
“Guillain-Barré syndrome (GBS) is an autoimmune condition that affects the peripheral nervous system. It results in progressive weakness and loss of feeling that evolve over several days. Most patients are admitted to hospital and about one-third need to be put on a ventilator. The symptoms generally reduce over a period of weeks to months but many are left with long-term weakness and 3%–10% die.
“The majority of GBS patients have a recognised infection before GBS onset. Campylobacter is the single most commonly identified infection. In NZ we have about 100 GBS cases a year and campylobacter infection is estimated to accounts for about 30% of them.”
How would NZ respond if we had an increase in Zika cases in the country? What facilities do we have to screen and treat people with suspected infections? What systems do we have to identify pregnant women who might be infected and screen their unborn babies for possibly birth defects?
“There have been no locally acquired Zika infections in NZ. An outbreak of local transmission would be considered a public health emergency and would result in a very vigorous biosecurity response. Such an event is not thought to be likely given that NZ mosquitoes are not considered to be good vectors for Zika virus.
“If Zika infection is suspected in a returning traveller, based on their symptoms and travel history, then their doctor could request a blood or urine test for evidence of Zika infection. Laboratories in Auckland, Wellington and Christchurch have the capacity to test for this virus. Any infected person with serious symptoms would be admitted to hospital for supportive treatment. There is no curative treatment or vaccine.
“NZ has good antenatal services which would be well placed to arranging testing for Zika infection if a pregnant women presented with symptoms and risk factors (such as travel history to an infected area). These services can also check on the baby’s development using ultrasound scans which would show major birth defects such as microcephaly if they were present.”
What are the recommendations for travellers going to Rio, or other countries where Zika is present? What recommendations specifically for pregnant women, or anyone who might become pregnant?
“Recommendations for travellers to Zika affected areas are well described on the Ministry of Health website.
“All travellers should take precautions to avoid mosquito bites, particularly:
- Use an effective insect repellent;
- Wear long-sleeved shirts and long pants;
- Stay in screened or air-conditioned accommodation.
“Because the mosquitoes that transmit Zika are active during daylight hours, it is necessary to use these precautions throughout the day.
“The NZ Ministry of Health advises women who are pregnant or plan to become pregnant to defer travel to Zika affected areas. If such women cannot defer such travel, then they should talk with their health-care provider about how to minimise the risk of infection.
“Both men and women need to consider precautions, such as use of condoms, to prevent sexual transmission of the virus if they have been in an affected area. This especially applies to men with pregnant partners who need to abstain from sexual activity or use condoms for the duration of the pregnancy, whether they have symptoms or not.”
Professor John Crump, McKinlay Professor of Global Health, Dunedin School of Medicine, University of Otago
What are the symptoms of Zika infection in most people – is it different in pregnant women or people with suppressed immune systems? How long does it last and how long do people normally take to recover?
“Most people (80%) with Zika virus infection have no symptoms and remain well. For the 20% who develop symptoms, 90% develop a rash, 65% have fever or joint pains. About half get conjunctivitis without pus (red eyes).
“Rash and fever are common symptoms of a number of other tropical infections, including dengue and chikungunya. In those unlucky enough to get ill, symptoms could last for several days and sometimes longer. Zika virus infection is not more severe in pregnant women, but they may pass the infection to their foetus leading to risk for birth defects, especially babies with small brains (called microcephaly).”
What are the risks of developing a serious side-effect, such as Guillain-Barré syndrome (GBS)? What is GBS and what effects does it have in sufferers? What other illnesses can lead to GBS and is there any understanding about who is more susceptible?
“The risk of developing serious complications of Zika virus infection like Guillain-Barré syndrome (GBS) is very low. GBS is a disorder in which the immune system attacks peripheral nerves resulting in tingling or weakness usually of the legs, but sometimes spreading to other parts of the body.
“In severe cases, breathing may be compromised and mechanical ventilation required. Most patients with GBS recover over a few weeks or months but about 30% still have weakness after 3 years. Campylobacter which is a common cause of diarrhoea in New Zealand that is associated with eating poorly-cooked chicken is also associated with GBS. We don’t know if any people are more susceptible to Zika virus-associated GBS.”
How would NZ respond if we had an increase in Zika cases in the country? What facilities do we have to screen and treat people with suspected infections? What systems do we have to identify pregnant women who might be infected and screen their unborn babies for possibly birth defects?
“Unlike the southern United States, New Zealand lacks the mosquito vectors required to transmit Zika virus. An increase in cases in New Zealand would most likely be due to travel to areas with active Zika virus transmission or onward sexual transmission of Zika virus.
“The New Zealand Ministry of Health has guidelines for healthcare providers for dealing with Zika virus in pregnancy. New Zealand has a registry of pregnant women with Zika virus infection, as well as enhanced surveillance for babies born with small heads to pick up potentially affected neonates and infants who were not identified earlier.”
What are the recommendations for travellers going to Rio, or other countries where Zika is present? What are the recommendations specifically for pregnant women, or anyone who might become pregnant?
“Pregnant women are advised not travel to areas with Zika virus transmission. Travellers should take mosquito avoidance measures. Correctly use condoms or abstain from sex 8 weeks after travel to an area with active Zika virus transmission or 6 months after symptomatic infection. Men who have travelled to areas with active Zika virus transmission with pregnant partners should use condoms or not have sex for the duration of pregnancy. Couples who want to get pregnant should wait 8 weeks after travel to areas with active Zika virus transmission or 6 months after symptomatic infection.”
Dr José Derraik, Senior research fellow, Liggins Institute, University of Auckland
What new research has been coming out regarding which mosquito species could potentially carry Zika? How does this relate to the mosquitoes we have in NZ (and where those mosquitoes are distributed)?
“The known mosquito vectors of Zika virus are Aedes aegypti and Aedes albopictus. However, recent evidence from the Oswald Cruz Foundation in Brazil has indicated that Culex quinquefasciatus may also be a vector of this virus. Experimental infection of Culex quinquefasciatus with Zika virus under laboratory conditions lead to the detection of virus in salivary glands of the mosquito 3 days after infection, which is an indication that the species is a potential vector of the virus.
“Subsequently, researchers from the same institute have detected Zika virus from unfed Culex quinquefasciatus mosquitoes collected from urban areas in Recife (North-eastern Brazil). As the specimens were unfed, the virus was circulating in the mosquitoes’ organs and not simply present in a recently-ingested blood meal, indicating that the mosquitoes were naturally infected with Zika virus. As a result, there is increasing evidence thatCulex quinquefasciatus could play a role in the transmission of Zika virus to humans.
“The relevance to New Zealand is that while Aedes aegypti and Aedes albopictus are not present here, Culex quinquefasciatus has been in this country since at least 1848. It is present in much of the North Island and in northern areas of the South Island. It is considered to be a species of ‘domestic’ habits, with a tendency to occur in association with humans. It breeds in a variety of man-made habitats, including polluted waters in drains and septic tanks. Culex quinquefasciatus is considered a pest in some urban areas, and it will often come indoors to bite humans in the night time.
“In addition, the ability of other Aedes species to transmit Zika virus is unknown, such as the introduced Aedes notoscriptus, which thrives in close association with humans in northern New Zealand and is a laboratory vector of other flaviviruses. Therefore, although the risk of Zika virus transmission to humans is much lower in New Zealand than in other countries, this possibility cannot be simply disregarded.”
How important is it that the global science community works quickly and in collaboration to confirm the link and inform public policy?
“It is clearly important that researchers, clinicians, and public health authorities work collaboratively across national and international borders. In fact, international collaboration is essential in our highly globalized world, whether there is rapid and intense movement of people (and therefore pathogens) between countries. This is important not only to halt the spread of epidemics into new areas, but also to learn as much as possible about the dynamics of a particular disease within the shortest time-frame possible.
“Recently, the threat of Zika virus has triggered a large number of studies around the world, with preliminary findings being continuously made available to promptly underpin appropriate public health measures.”
What are the recommendations for travellers going to Rio, or other countries where Zika is present? What are the recommendations specifically for pregnant women, or anyone who might become pregnant?
“Detailed guidelines have been put forward by a number of health authorities, such as the US Centers for Disease Control and Prevention (CDC), whose main recommendations are adapted below.
“As it is usual for the prevention of any mosquito-borne disease, travellers should take protective measures to avoid being bitten by mosquitoes. These include using appropriate insect repellents (e.g. containing DEET), sleeping under a mosquito net, staying in areas where doors and windows have screens and using long-sleeved shirts and long pants.
“It is recommended that pregnant women simply do not travel to areas where there is ongoing transmission of Zika virus.
“For women attending the Olympic Games who plan to become pregnant, they should wait 8 weeks after their return to New Zealand before attempting pregnancy. If their partner has symptoms of Zika virus infection, this period should be extended to 6 months.
“Sexual transmission of Zika virus from male to female has been repeatedly reported, but more recently there has been a case of female to male transmission. As a result, it is advisable to use condoms during intercourse, not only while in Rio but for 8 weeks after returning to New Zealand (for 6 months in case a male partner has developed symptoms of Zika virus infection).”
What about people coming back from overseas possibly infected with Zika – should they take precautions to avoid being bitten by local mosquitoes?
“The Olympic Games are happening during the Southern Hemisphere winter. As a result, the risk of local transmission of Zika virus in New Zealand is very low, because mosquito populations in the country tend to dwindle considerably at this time of the year. Nonetheless, one can never be too careful, and it would be advisable to avoid being bitten by mosquitoes in New Zealand for at least 3 weeks after first developing the symptoms of Zika virus infection.”