By Dr Eddy Bajrovic*
Could condoms help protect Australian babies from the dangers of the mosquito-borne Zika virus?
The answer’s ‘yes’.
Let me explain why…
Much has been written recently about the suspected link between the mosquito-borne Zika virus and a sudden spike in microcephaly in infants born to women infected during pregnancy in Latin America.
Experts from around the globe are studying the phenomenon. However, it’s looking increasingly likely that the virus is the cause of the condition, which results in the child being born with a smaller skull and brain, leaving them with lifelong neurological damage.
But, it’s not only women already pregnant or those planning to conceive who should either avoid travel to Zika-infected regions – which now includes much of the Caribbean, the Americas, and parts of SE Asia, the Pacific and Africa – or, if they do go, take measures to prevent being bitten by mosquitoes.
Their male partners also should be aware of the potential threat Zika could pose.
And, that’s where condoms come in.
What we now DO KNOW…
Scientists are still unravelling the mystery behind Zika and the role sex plays in its transmission.
But, here’s what we do know:
- The Zika virus can be spread by a man to his sexual partners – male or female. There have only been a handful of reported cases, but many others may have gone unrecognised. If used correctly, condoms could prevent infection.
- So far, in cases of sexual transmission of Zika, most of the men had obvious symptoms, which can include rash, red eyes, a low-grade fever and joint pain lasting up to a week. However, there’s also been a case where the virus was transmitted days before symptoms developed.
- The virus remains present in semen longer than in blood. Zika usually clears the bloodstream in 5-7 days – 10 at the most. There’s no evidence of any risk to a future pregnancy if a woman has had Zika in the past.
- While data on late-pregnancy infections is limited, it is known that a mother infected with Zika late in the third trimester can pass on the virus to her unborn infant without microcephaly occurring. (Also, there are no reports of infants being infected through breast milk and mothers are being urged to breastfeed – even those living in areas where the virus occurs.)
What we still DON’T KNOW…
However, what is not known about Zika and sex is:
- How long the virus remains present in the semen of infected men. Zika has been found to persist in semen for up to 60 days in one case. (America’s Centers for Disease Control and Prevention hopes to start a study to investigate this further soon.)
- If men who get infected, but don’t develop Zika symptoms, could also have the virus in their semen and be able to infect a partner through sex.
- If an infected woman can transmit Zika virus to a partner through sex of any type.
Testes ‘immune’ to Zika
It may seem curious that Zika is transmitted in semen. Many sexually transmitted diseases are also passed on via blood rather than mosquitoes. (HIV can’t be transmitted by mosquitoes.)
However, it’s long been known that certain parts in the human body, including the semen-producing male testes, are ‘immune privileged’. Others include the eyes, articular cartilage, and to some degree the central nervous system.
That is, when certain infections enter these organs, our immune system doesn't attack them. (In the case of the testes, this ‘immunity’ may protect a male’s ability to reproduce).
Because some viruses can survive in the testes for longer periods, they can be transmitted during sex.
While we don't yet know definitively how long Zika can live in semen, we do know that other viruses – including the deadly Ebola virus – can remain viable in the testes for long periods.
Pregnant? Here’s what to do
Because of the link between the virus and birth defects, a pregnant woman travelling to a Zika-infected region should take measures to prevent infection.
There is no vaccine yet, so avoiding mosquito bites is our first line of defence.
To further protect their foetus during pregnancy, women who have a male partner who lives in or has travelled to an area with an active or recent Zika outbreak should:
- Refrain from unprotected sex with that partner for the duration of that pregnancy, or
- Use a condom effectively every time they have sex while pregnant.
If you think your male partner is infected or may have had Zika, tell your GP or travel doctor about:
- His travel history
- How long he stayed
- The type of accommodation
- If he took steps to prevent mosquito bites
- If you had sex without a condom
Three-month infection period
Even after leaving an infected area, a man should avoid mosquito bites if he is returning home to a place that has Aedes mosquitoes.
In Australia that’s tropical north Queensland, where local Aedes aegypti populations could spread the virus into the local community for the first time.
The current concern does not apply to women who are not pregnant or do not plan to get pregnant in the near future.
In fact, getting infected may provide extremely long-lasting immunity – probably for life.
However, to avoid infection or an unplanned pregnancy, a woman whose male partner has a confirmed, symptomatic Zika infection should either use condoms or refrain from sex for at least 3 months after her partner’s symptoms are past.
After that period it’s thought the risk of infection will have passed.
Prevent bites: Pack repellent
The two species of Aedes mozzies that spread Zika – Aedes aegypti and Aedes albopictus – also transmit the dengue and chikungunya viruses throughout the tropical world. They are also responsible for yellow fever in South America’s Amazon Basin and sub-Saharan African countries.
Aedes mozzies love people: The females bite in and around any form of urban accommodation during the daylight hours – particularly around dusk and dawn – seeking the blood meal they need to breed.
DON’T FORGET… To take along an effective personal insect repellent: It’s the most important weapon in the arsenal of every traveller visiting areas where mosquito-borne diseases occur. Travel-strength repellents should contain a proven active ingredient such as DEET, Picaridin, or oil of eucalyptus (PMD). DEET formulations containing 40% active ingredient will protect for 6 hours, 20%-30% DEET = 4 hours, 10% = 2 hours. Picaridin and PMD are equally effective and safe. Travelvax stocks a range of these repellents.
FORGET ABOUT… Wristband repellents, phoney phone apps, ‘natural’ repellents, vitamin B, or mosquito coils and sticks. Their protection is marginal at best.
Call us before you fly
Aussie travellers can also follow the example of our Olympics Games athletes and officials, who are taking permethrin-impregnated bed net to sleep up under in Rio in August. Travelvax Australia sells quality single and double nets, as well as speed nets online and at our clinics.
Finally, before you fly out, find out if mozzie diseases could be a health risk at your destination by calling Travelvax Australia’s travel health advisory service on 1300 360 164 (toll-free from landlines).
You can also make an appointment for a pre-travel medical consultation, any vaccinations needed for the trip and personalised advice from medical professionals experienced in travel medicine.
* Dr Bajrovic is Medical Director of Travelvax Australia.
Read more on insect-borne viruses commonly found in the tropics, including dengue, chikungunya, malaria and yellow fever.