With three King County residents now under public health surveillance following potential exposure to the Andes hantavirus linked to the MV Hondius cruise ship outbreak, many Seattle-area residents are asking the same question: what exactly is hantavirus, and what should I watch for?
Here is what public health authorities and medical experts say.
What Is Hantavirus?
Hantavirus is a family of viruses carried primarily by rodents, which shed the virus through their urine, faeces, and saliva. Humans typically become infected by breathing in air contaminated with infected rodent droppings or urine, touching contaminated surfaces and then touching the mouth or nose, or in rare cases being bitten by an infected rodent.
The Andes hantavirus, the strain linked to the MV Hondius outbreak, is unique among known hantavirus variants in that it is the only strain capable of spreading from person to person, though health officials emphasise that this typically requires prolonged and close contact with an infected individual rather than casual exposure.
What Are the Symptoms?
Hantavirus infection progresses in stages, and early symptoms can be difficult to distinguish from influenza or other common respiratory illnesses. The incubation period, meaning the time between exposure and the onset of symptoms, ranges from one to eight weeks, with most people showing signs of illness between two and four weeks after exposure.
Early symptoms typically include fever, fatigue, and muscle aches, particularly in the thighs, hips, back, and shoulders. Headaches, dizziness, chills, and abdominal problems including nausea, vomiting, diarrhoea, and stomach pain can also occur in the early stage. These initial symptoms can last anywhere from a few days to a week before the illness either resolves or progresses.
In some cases, hantavirus progresses to a serious condition called Hantavirus Pulmonary Syndrome, or HPS. This is the stage at which the disease becomes life-threatening. Symptoms of HPS include a cough that produces fluid from the lungs, severe shortness of breath, and a sensation of tightening in the chest. At this stage the lungs can begin to fill with fluid rapidly, and the condition can become fatal within hours if not treated. HPS has a case fatality rate of approximately 38% in the United States, according to the Centers for Disease Control and Prevention.
Who Is Most at Risk?
Anyone exposed to infected rodents or their droppings is potentially at risk. Activities that increase risk include cleaning out sheds, cabins, or storage areas that may have been used by rodents, working in agricultural settings, camping in areas with high rodent populations, and in the specific case of the Andes strain, close contact with an infected person.
In the context of the MV Hondius outbreak, public health officials have noted that the source of infection on board the ship remains under investigation, given that the vessel’s operators have said no rodents were found on board.
Is There a Treatment?
There is no specific antiviral treatment approved for hantavirus infection. Medical care focuses on supportive treatment, including supplemental oxygen, mechanical ventilation for patients with severe respiratory symptoms, and management of fluid levels. Early hospitalisation and intensive care significantly improve survival outcomes for patients who develop HPS.
What Should You Do If You Are Concerned?
Anyone who believes they may have been exposed to hantavirus, whether through contact with rodents, their droppings, or potentially infected individuals, should contact a healthcare provider promptly and describe the nature and timing of the exposure. Do not wait for symptoms to appear before seeking medical advice.
King County residents with specific concerns related to the MV Hondius outbreak can contact Public Health Seattle and King County directly. The agency has emphasised that the risk to the general public in the Seattle area remains low.
