Hantavirus Or Norovirus: Which Cruise Ship Outbreak Should Concern Us More?

When two people died in the hantavirus outbreak linked to the Atlantic expedition cruise ship MV Hondius, Dr Rajeev Jayadevan, who was also Co-Chairman of the National IMA COVID Task Force, had told Times Now Digital why ships become ideal places for viruses to spread. And just days later, another cruise ship, Caribbean Princess cruise ship, reported a norovirus outbreak where over 100 people fell sick. If you compare the numbers alone, 8 against 100 seems jarring. Naturally, one would assume the latter is the bigger threat but according to Dr Jayadevan, the answer is not that straightforward.Revisiting what he had explained to us earlier, there are broadly two kinds of viruses - those with an outer lipid coating and those without one. Hantavirus

belongs to the first category. Norovirus belongs to the second. “As we know, hantavirus is a virus with an outer layer and norovirus is a naked virus,” Dr Jayadevan explained. “What it means is that while you can wash away hantavirus with soap and water, norovirus is difficult to fight.” And that difference changes everything about how the viruses behave.“It just sticks to surfaces and you can’t get it off easily. You wipe with soap and water and it is not necessarily going to clean it away. You really have to try hard to eliminate this virus,” he said. That, according to him, is the real problem with norovirus. Since it has no lipid coat or fat coat, conventional cleaning methods are often not enough. But does the speed at which it spreads make it more dangerous too? Well, the answer is somewhat complex yet simple.The first thing to understand is that norovirus is a gastrointestinal virus. It causes vomiting, diarrhoea and stomach infections. And because infected people constantly touch common surfaces from bathroom handles, lift buttons, toilet seats, dining tables, it becomes incredibly easy for the virus to spread from one person to another. “In a cruise ship, it becomes all the more easy because people have come from all over places and supplies come from many places,” Dr Jayadevan explained. “It is just an ideal situation for the virus to spread.” Cruise ships, after all, are closed ecosystems. Thousands of people eat together, touch the same surfaces and move within confined shared spaces for days at a stretch. That is why norovirus outbreaks on ships are not unusual.

Still, Dr Jayadevan pointed out that while norovirus spreads rapidly and can incapacitate a large number of people very quickly, it is not usually life-threatening. “A concern with norovirus is that it’s going to incapacitate a lot of people really quick. But it rarely kills people unless they are already very frail, critically ill or unable to access medical care.” And that is where hantavirus becomes a completely different kind of concern.“The hantavirus outbreaks are exceptionally rare but the strain we are talking about here is one that affects the lungs.” He explained that most hantaviruses seen across Asia and parts of the Eastern Hemisphere tend to affect the kidneys or sometimes cause mild illness. But the strains found in North and South America including the Andes virus, are different. “They are more likely to cause pulmonary syndrome or lung affliction, which can become life-threatening,” he explained.Dr Jayadevan clarified another important point that often gets misunderstood: the much discussed 40 per cent death rate. “That 40 per cent is specifically the chance of dying if a person develops lung involvement. It is not the overall mortality for every hantavirus infection.”Not everyone infected develops severe disease. Some may even have mild symptoms. But once the lungs are affected, the situation can turn critical very fast. And that is why, despite the smaller number of cases on the cruise ship, hantavirus triggered far greater fear among doctors and health authorities.At the time of the interview, several people linked to the outbreak were still hospitalised and one was reportedly in the ICU. “So yes, greater concern for the individual is with hantavirus,” Dr Jayadevan said. “Whereas from a community standpoint, norovirus can be pretty devastating because it can make a lot of people sick very quickly.”He gave a simple example. “Imagine a wedding party where 100 people suddenly fall sick. Where do they all go? Everyone may need IV drips and medical attention at the same time.”Towards the end of the conversation, Dr Jayadevan also referred to a 2020 paper published in the The New England Journal of Medicine about an Andes virus outbreak in Argentina. The researchers had reportedly traced every infection in extraordinary detail, who attended a birthday party, where each person sat and who later became infected. “He tracked all the cases, where each person sat and how far away they were from the index case,” Dr Jayadevan said. The findings were important because they suggested that under certain circumstances, some hantaviruses may spread between humans more than previously assumed. But even then, hantavirus is not considered a rapidly spreading virus like COVID-19 or norovirus. “It is more of a slow-burn infection. It does not rapidly spread from person to person.”And perhaps that is the simplest way to understand the difference between the two outbreaks. Norovirus spreads fast and makes many people miserable at once. Hantavirus spreads slowly, rarely causes outbreaks, but when severe disease develops, it can turn deadly.