Travel and a desire to have children are not mutually exclusive, but they do raise questions. Many couples plan a long-haul trip or their honeymoon and would like to become pregnant as soon as possible afterwards. Others are already pregnant when a business or family trip to a tropical country comes up and when they hear the term Zika, uncertainty and worries arise.

We spoke to Dr Christina Coelius, a senior consultant at the Department of Obstetrics at the University Hospital Zurich, about the most important questions about Zika and pregnancy.

Dr. Coelius, many people remember the images from the Zika virus epidemic in South America in 2015/2016. How has the situation changed since then? Do travelers still need to be just as worried today?

In 2015, the virus spread from Brazil to large parts of the American continent and the Caribbean; by the end of 2016, the WHO estimated that around 4,000,000 people had been infected. Since then, the number of infections has fallen significantly, which is most likely explained by so-called herd immunity. Nevertheless, there are still regions of the world where the virus is endemic, meaning it continues to circulate.

How common are Zika infections among travelers in reality? Is this something you still see frequently in clinical practice in Switzerland?

Overall, we see Zika infections in travelers very rarely. In 2016, mandatory reporting was introduced in Europe and also in Switzerland. Since then, 75 cases have been registered with the Federal Office of Public Health. In 2023, the first case since 2019 was reported, meaning that for four years there had been no registered cases. When Zika does occur here, it is almost always in connection with travel – but in everyday clinical practice, it is a very rare exception.

What kinds of malformations and other consequences can a Zika infection during pregnancy have for the unborn child?

If a Zika infection occurs during pregnancy, it can lead to very serious malformations and other complications in the child. A typical feature is so-called microcephaly, meaning the head is too small in relation to the body. There can also be severe brain malformations, such as calcifications in the brain or malformations in the area of the cerebellum.

In addition, there may be microphthalmia, meaning the eyes are too small, hearing loss, and malformations of the limbs, for example clubfoot. Lung hypoplasia, in which the lungs are not fully developed, has also been described.

Zika infections during pregnancy can also lead to growth restriction, meaning the child is overall too small. An increased rate of miscarriage and a higher risk of preterm birth have likewise been reported.

It is assumed that if infection occurs in the first trimester, a Zika-associated malformation syndrome can develop in around 11% of cases. However, the fetal brain develops throughout the entire pregnancy and continues to develop after birth. This means that infection at any stage of pregnancy can negatively affect brain development.

The term Guillain–Barré syndrome is often mentioned in connection with Zika. What exactly is it?

Guillain–Barré syndrome is a rare autoimmune disease that affects the nerves and can lead to ascending paralysis. Symptoms often begin in the hands and feet; in the worst case, it can result in paralysis of the respiratory muscles.

The risk of developing Guillain–Barré syndrome following a Zika infection is estimated at around 2.4 cases per 10,000 infected individuals. It affects the infected person, so in our context the pregnant woman or her partner.

Many of our patients are surprised to learn that not only the (potential) mother needs to protect herself, but that sexual partners can also transmit the virus. How does that work exactly?

The Zika virus can be detected in both semen and vaginal secretions and can therefore be transmitted sexually. An infected partner can thus pass the infection on to the expectant mother.

For this reason, with Zika it is particularly important to also take the partner’s travel history into account and to test them if necessary. Protecting the partner is a crucial factor in reducing the risk to the pregnancy.

What do you advise a woman who is already pregnant and has a trip planned to a Zika area? Some trips are unavoidable for professional or family reasons…

Zika is transmitted by particular species of mosquito that are found in these regions. This is why consistent mosquito protection – day and night – is recommended for the entire trip. This includes mosquito repellents containing DEET, which are considered safe to use during pregnancy, as well as clothing impregnated with permethrin. Wearing long, light-coloured clothing and avoiding dawn and dusk, when mosquitoes are particularly active, is also sensible.

It is also important to know that these mosquitoes are found mainly in areas below around 2,000 metres above sea level. In higher-altitude cities, the risk is somewhat lower, but protective measures should still be followed.

Because of the possibility of sexual transmission, couples should also either abstain from sexual intercourse or use condoms consistently – regardless of whether the intercourse is vaginal, anal or oral.

Many couples ask us: “After a trip, when can we start trying for a baby?” Do the same waiting times apply to women and men?

As a general rule of thumb, it is recommended that couples avoid becoming pregnant for three months after travelling to an area with possible Zika transmission. This recommendation applies to both partners.

If we differentiate more precisely, men should wait at least three months, and women at least two months. This relates to how long the virus can be detectable in the genital tract. If a couple has travelled together to a Zika area and wants to be on the safe side, a waiting period of three months is a good and pragmatic guideline.

What message would you like to give to couples who are trying for a baby and feel unsettled because they are planning a trip or have just returned from one?

For couples in whom conception has not yet occurred, I would recommend, in case of doubt, waiting for three months. This three-month period is based on the data from reported cases in which Zika infection was associated with pregnancy complications. Once this period has passed, you can be highly confident that there is no relevant infection. Until then, couples should either abstain from sexual intercourse or use condoms consistently.

If a trip is still being planned – typically a honeymoon – and it is clear that pregnancy is desired in the near future, I would, in case of doubt, avoid destinations where the virus occurs. There are very good interactive maps available that show Zika risk by region. Often it is a good alternative to stay within Europe. A classic example of a popular honeymoon destination that is further away but currently considered free of Zika risk is Mauritius.

Dr Coelius, thank you very much for this interview!

Interview: Sofia Ricar