May 3 (UPI) — Three passengers on a cruise ship off West Africa have died from suspected hantavirus and at least three others are receiving medical treatment, cruise and health officials said Monday.

The cruise ship Hondius of Oceanwide Expeditions is currently off the coast of Cape Verde and is experiencing a “serious medical situation,” the Dutch tour company said in a statement.

It confirmed three passengers had died, one passenger was receiving treatment in intensive care in Johannesburg, South Africa, and two crew members required “urgent medical care.”

Cape Verdean health officials have assessed two symptomatic suspected cases of hantavirus on the vessel but had not decided whether to transfer them to local medical facilities, it said.

“The priority of Oceanwide Expeditions is to ensure that the two symptomatic individuals on board receive adequate and expedited medical care,” it said, adding that Dutch authorities have agreed to lead a joint effort to repatriate the two individuals from Cape Verde to the Netherlands.

UPI has contacted South Africa’s Department of Health for comment.

The World Health Organization said online that it was working with member states and Oceanwide Expeditions to secure the medical evacuation of the two crew members.

“Rapid, coordinated action is critical to contain risks and protect public health,” WHO Director-General Tedros Adhanom Ghebreyesus said in a social media statement.

The WHO also said it would conduct a full risk assessment and support those on board the Hondius.

Investigations, including further laboratory testing, were ongoing, as was virus sequencing, according to the United Nations health body.

Hantaviruses are a family of viruses that can cause serious illnesses and death, according to the U.S. Centers for Disease Control and Prevention.

The virus is contracted through contact with rodents, such as rats and mice, as well as through exposure to their urine, droppings and saliva.

Symptoms, which tend to show one to eight weeks after contact with an infected rodent, include fatigue, fever and muscle aches, and are followed by headaches, dizziness, chills and abdominal issues, such as nausea, vomiting, diarrhea and abdominal pain, the CDC said.

“While rare, hantavirus may spread between people and cal lead to severe respiratory illness and requires careful patient monitoring, support and response,” the WHO said.