Experts have issued a stark warning that individuals exposed to the deadly hantavirus could potentially become 'super-spreaders', with symptoms taking up to two months to appear after initial exposure. This concern arises as two British individuals are currently self-isolating in the UK following potential exposure to the hantavirus on a cruise ship, the MV Hondius, which sailed from Argentina to Cape Verde. More than 20 other Britons remain on board the vessel and are expected to face quarantine for up to eight weeks upon their return.

While officials state the risk to the public remains low, research from the US Army Medical Research Institute of Infectious Diseases indicates that the Andes strain, identified on the ship, can spread rapidly between humans. The exact source of the outbreak is still unknown; it could be due to rodent contamination on the vessel itself or passengers being exposed to the virus prior to boarding. Reports suggest some passengers visited a rubbish tip for a birdwatching trip before the ship departed, potentially exposing them to the virus. If this hypothesis is correct, symptoms would not have appeared until approximately a week later, by which time the ship would have already sailed.

Hantavirus typically transmits from rodents to humans when contaminated droppings are stirred up, creating airborne particles that are then inhaled. Infection can also occur if saliva, urine, or feces from an infected rodent come into contact with a person's eyes, nose, or mouth. While initial hantavirus symptoms mimic the flu, the Andes strain is unique in its ability to spread human-to-human through prolonged close contact, such as sharing food, sleeping in the same bed, or between sexual partners.

The incubation period for hantaviruses can extend up to eight weeks before symptoms of one of two severe illnesses manifest. Early stages often involve increased fatigue, followed by fever and muscle aches, similar to influenza. Diagnosing hantavirus within the first 72 hours is notoriously difficult due to its resemblance to flu or Covid-19 symptoms, and approximately 30 percent of infected individuals are thought to be asymptomatic. Not everyone infected will develop serious complications.

The disease typically progresses down one of two severe routes: Hantavirus Pulmonary Syndrome (HPS) or Hemorrhagic Fever with Renal Syndrome (HFRS). HPS is a serious and potentially fatal illness affecting the lungs. Alongside flu-like symptoms, around half of HPS patients may experience headache, dizziness, chills, and gastrointestinal issues like nausea, vomiting, diarrhea, and abdominal pain. Four to ten days after the initial phase, more severe symptoms appear, including coughing, shortness of breath, and chest tightness as the lungs fill with fluid, often requiring intubation to assist breathing. Approximately 40 percent of individuals who develop these respiratory symptoms and require urgent medical attention will die from the disease.

HFRS is a severe and sometimes deadly disease that impacts the kidneys, leading to internal bleeding and eventually organ failure. Symptoms usually develop more quickly than HPS, causing intense headaches and abdominal pain within two weeks of exposure. The onset is sudden, with fever, chills, nausea, and blurred vision. Some patients may also exhibit flushing of the face, inflammation or redness of the eyes, or a distinct butterfly rash on the cheeks. In rare instances, symptoms may take up to eight weeks to manifest.

As HFRS progresses, patients may experience a drop in blood pressure, leading to lightheadedness, nausea, and confusion, coupled with internal bleeding and eventual kidney failure. When caught at this late stage, urgent medical attention is required to filter toxins from the body and maintain fluid levels. HFRS patients are typically admitted to intensive care, isolated to minimize transmission risk, and undergo dialysis to remove waste products from the blood and support kidney function.

Currently, there is no specific treatment for hantavirus infection, but early medical support can significantly improve survival rates. While new treatments are being trialled, no widely available vaccines exist to protect against the virus, although a limited number are used in China and South Korea, where certain strains are more prevalent. An estimated 150,000 cases of HFRS are reported worldwide each year, predominantly in Europe and Asia, with over half typically occurring in China.