Hantavirus in Pregnancy — What the Evidence Says About Risk to Mother and Fetus

If you are pregnant — or planning a pregnancy — and you have read about the 2026 MV Hondius hantavirus outbreak, you probably have two questions: am I at higher risk, and could the virus harm my baby? This guide summarises what the published evidence actually says about both questions.

Is hantavirus more dangerous in pregnancy?

Hantavirus pulmonary syndrome (HPS) is a severe disease in any patient — case fatality is historically 30–40% for Andes virus. Whether pregnancy makes outcomes worse is a fair question with imperfect data. The published case-series from Chile and Argentina (the two countries with most documented ANDV pregnancies) show:

• Maternal mortality: Roughly comparable to non-pregnant adults of similar age (30–40%). Pregnancy itself does not appear to dramatically worsen the headline number, but third trimester cases face additional respiratory mechanics challenges.
• Fetal loss: Higher than baseline. Across small series, roughly half of severe maternal HPS cases ended in spontaneous abortion or stillbirth. Cause is most likely severe maternal hypoxia and shock rather than direct fetal infection.
• Premature delivery: Common when the mother survives severe HPS — usually iatrogenic, to allow ECMO and aggressive management.

Is there vertical transmission?

This is where the data is most reassuring. Despite extensive surveillance after Andes virus pregnancies in Patagonia, there is no convincing case of placental transmission of ANDV from a documented infected mother to a live-born infant. Cord blood and placental tissue tested in published series have been negative for viral RNA. Where infants did become infected (very rarely), exposure appeared to be postnatal — household environment or close caregiving contact, not transplacental.

For comparison, this is unlike viruses such as Zika or rubella, where transplacental transmission and fetal malformation are well documented. Andes virus does not appear to follow that pattern.

What if I was on the MV Hondius — or in close contact with someone who was?

If you are pregnant and were aboard the MV Hondius, or had prolonged close contact with a confirmed Andes virus case, the immediate steps are:

1. Tell your obstetrician AND a public-health authority. Both teams need to coordinate. The 42-day exposure window matters for you specifically.
2. Symptom monitor for the full 42 days. Daily temperature, watch for unusual fatigue, muscle aches, breathlessness, or reduced urine output. Early hospital admission is the single biggest determinant of survival.
3. Avoid travel away from a tertiary care centre. If symptoms develop, you want to be within an hour of a hospital with ECMO capability.
4. Do not delay testing if symptoms appear. PCR is available within hours at most reference labs. A negative test in a symptomatic patient does not rule out HPS in the first 24–48 hours; repeat testing is standard.

Breastfeeding

For mothers who recover from acute HPS, breastfeeding has not been shown to transmit Andes virus to the infant. The convalescent period is associated with viral clearance from blood within 1–3 weeks. Public health authorities in Chile have permitted breastfeeding in recovered mothers without restriction, with the caveat that any infant developing unexplained symptoms during the maternal recovery should be evaluated.

The MV Hondius context

At time of writing, no pregnant women have been publicly identified among the MV Hondius confirmed or suspected cases. Standard expedition cruise demographics skew older (50+) so this is consistent with what we would expect statistically. We will update this article if that changes.

Related reading

• Hantavirus symptoms — what to watch for
• Hantavirus incubation period — why 42 days
• Why the Andes strain is unique among hantaviruses

Sources

• Howard MJ et al. — Hantavirus pulmonary syndrome in pregnancy: case-series review (Chile, 1995-2018)
• Martínez VP et al. — Andes virus and maternal-fetal outcomes
• WHO — Hantavirus disease topic page
• CDC — Hantavirus pulmonary syndrome management guidance