Hantavirus Concerns from Cruise Ship Passengers

The MV Hondius, a cruise ship affected by a hantavirus outbreak, has reached its final destination. Now, it’s all about waiting.

The Andes strain of hantavirus, which has a death rate of approximately 40%, was identified among passengers from around 24 countries. This situation marks a significant challenge for global health officials in managing contagions post-COVID-19 pandemic. Different nations are taking varied approaches to monitor those potentially exposed and calm anxious public sentiment about the virus’s reach.

Passengers who boarded the ship in early May are now entering the highest risk period for developing symptoms, as noted by infectious disease experts.

A passenger from the ship, who was in quarantine in Canada, has tested positive for the Andes strain of hantavirus, as reported by the Public Health Agency of Canada.

“It wouldn’t be surprising if more cases pop up this week,” commented Dr. Isaac Bogoch, an infectious disease specialist at the University of Toronto.

Dr. Bogoch’s recent collaboration with Dr. Jason Andrews from Stanford focused on the incubation periods and spread of hantavirus in past outbreaks in Argentina, specifically from 1996 and 2018. Their findings are now awaiting peer review.

Their research suggests that the average incubation period for the virus is about three weeks.

The most recent illness on the ship was a German passenger who died on May 2, the same day the cause of the outbreak was identified. Until that point, many aboard were unaware they needed to take precautions.

While not every passenger may have been exposed, May 2 serves as a general timeframe for potential risk. Symptoms can take up to six weeks to manifest, which is why many countries are watching passengers for at least 42 days from their disembarkation on May 10.

Historically, Argentina has effectively contained the Andes hantavirus using established public health methods like testing and quarantining.

“Now, we depend on everyone acting correctly rather than just one country’s measures, which might introduce a greater margin for error,” Bogoch stated.

Countries are employing various techniques to monitor returning passengers.

Mandatory quarantines have been implemented in Spain and France, while the UK and the US recommend that passengers self-isolate voluntarily, with periodic check-ins by health officials.

Some individuals are quarantined in hospitals, while others are monitored from home.

Countries are also testing passengers at intervals to catch early signs of infection. However, US officials suggest not testing until symptoms appear, which Dr. Bogoch finds concerning. He noted that people might shed the virus days before symptoms emerge.

“If you solely rely on visible symptoms, you’ll likely overlook some cases,” he said, stressing the need for proactive testing.

Early testing could potentially lead to treatments being administered sooner. Although there are no specific drugs approved just for this virus, certain antiviral medications might help mitigate its severity, especially if given in the early stages.

The 18 passengers who returned to the US recently can choose to quarantine at home or at the National Quarantine Center in Nebraska.

CDC representatives have advised the cruise passengers to prefer the Quarantine Center for closer monitoring and prompt medical care if symptoms develop.

The CDC has also alerted several states about returning passengers, including those who traveled before the outbreak was recognized and those exposed during flights.

Currently, 41 individuals are being monitored across various states, including the 18 in quarantine. They’ve all been instructed to check their temperatures daily and report any symptoms such as headaches, nausea, or shortness of breath.

Those at risk have the option to quarantine at home, provided their local health department approves it and suitable accommodations are available.

The proposed guideline indicates that individuals with high-risk exposure should receive twice-daily in-person visits from public health officials.

However, Dr. Jennifer Nuzzo from Brown University expressed concern regarding the resources required for such oversight, especially considering funding cuts for local health departments.

The CDC has advised monitored individuals to avoid close contact with others and refrain from travel during this vulnerable six-week period.

That said, some individuals have already slipped through the cracks. For instance, two Hondius passengers from California and New York traveled internationally before the outbreak was identified. One has since been quarantined by UK authorities, while the other has been contacted by HHS, though details regarding their health remain scarce.

Quarantine Protocols

Some nations have adopted stricter quarantine measures.

In the Netherlands, for instance, passengers are under mandatory home quarantine, with daily check-ins with health authorities, while limited outings are allowed under specific conditions. The Rotterdam facility is preparing quarantine cabins for the international crew members of the MV Hondius.

Meanwhile, Great Britain allows passengers to return home after initial hospital evaluations, relying largely on voluntary compliance. Conversely, France and Spain are enforcing stricter legal requirements, necessitating mandatory reporting.

Passengers in France will need to stay in the hospital for at least 15 days, while Spain mandates at least a seven-day quarantine for those exposed to the Andes virus.

Passengers from Singapore will remain in the hospital for 30 days, followed by a 15-day phone monitoring period.

Countries shared their monitoring strategies during a recent WHO call that excluded the CDC, highlighting another divergence between US and other nations’ practices regarding testing in quarantine.

The CDC expressed their stance against testing individuals without symptoms, which experts warn might let early infection signs slip through.

This approach, which focuses on antibody testing after the body has reacted to the infection, might not catch cases in their early stages.

Dr. Marrazzo emphasized the importance of observing how this virus develops over time, seeing it as a significant opportunity for understanding.