WASHINGTON, United States  (AFP) — A passenger who was aboard the cruise ship MV Hondius and initially tested “mildly positive” for hantavirus has now tested negative for the rare disease, a spokesperson told AFP Thursday.

Kayla Thomas — a media coordinator at the University of Nebraska Medical Center, where 16 patients who were on the ship are being monitored — said, “both tests were negative by PCR and serology.”

The asymptomatic patient was initially under observation in a biocontainment unit after an initial “mildly positive” test that United States (US) medical personnel later deemed inconclusive.

He is now in a quarantine unit of the centre, which has specialised facilities for people potentially exposed to high-consequence infectious diseases.

There are 15 others, all asymptomatic, being monitored at the Nebraska Medical Center.

Two more people — one of whom experienced symptoms but tested negative — are being monitored at Georgia’s Emory Hospital.

David Fitter — the US Centres for Disease Control and Prevention (CDC) incident manager for the hantavirus response — told a press briefing Thursday that there are now 41 people in the United States being monitored by federal and local health authorities after potential exposure to hantavirus.

That figure includes the 18 people who were on the ship and are now under medical supervision in the clinical facilities in Nebraska and Georgia.

The rest are people who had returned home from the MV Hondius before the outbreak was identified, and others who may have been exposed during travel on flights.

The Kansas health department said in a statement that three individuals who had “a high-risk exposure to a person with confirmed Andes hantavirus” had been taken to a University of Kansas hospital for observation, without providing further details.

The CDC has said that “everyone under monitoring stay at home and avoid being around people during the 42-day monitoring period. We emphasise not to travel across all these groups,” Fitter said.

Health authorities have repeatedly emphasised that the broader risk to public health from the outbreak of the Andes strain of hantavirus — the only one known to spread between people — is low.

Globally, the death toll remains at three.