Unlike Covid-19, hantavirus not known for rapid human transmission, spreads through rodents: Experts

Amid concerns over two Indian nationals reportedly infected with hantavirus aboard an international cruise ship, public health experts on Friday said the cases appear to be isolated infections linked to a closed onboard environment, and there is no indication of community spread.

Amid concerns over two Indian nationals reportedly infected with hantavirus aboard an international cruise ship, public health experts on Friday said the cases appear to be isolated infections linked to a closed onboard environment, and there is no indication of community spread. However, they stressed the need for vigilance and rodent-control measures. Dr Puneet Mishra, Head of the Department of Community Medicine at AIIMS, Delhi, said hantavirus behaves very differently from highly transmissible respiratory viruses such as COVID-19. ''There are many types of hantaviruses, of which the Andes strain is causing the ongoing cruise ship outbreak. Hantaviruses circulate freely among rodents, and only occasionally infect humans,'' Dr Mishra told PTI. He said the Andes strain is among the few known hantaviruses capable of limited human-to-human transmission. ''The Andes strain is known for limited human-to-human transmission through prolonged close contact with respiratory secretions. This explains the spread of the virus on the cruise ship, which essentially is a closed environment where many individuals remain in prolonged close contact over an extended period of time,'' he said. According to the World Health Organisation (WHO), the two Indian passengers were among a small cluster of suspected infections identified aboard the vessel, and health authorities were monitoring contacts and undertaking precautionary measures. WHO officials noted that hantavirus infections are rare and are generally linked to rodent exposure rather than sustained human transmission. WHO Director General Dr Tedros Adhanom Ghebreyesus, who briefed the media on the virus on Thursday, said, ''While this is a serious incident, WHO assesses the public health risk as low''. Given the incubation period, he said, ''It is possible that more cases may be reported''. Dr Mishra said India has adequate capacity to detect and manage suspected cases, if required. ''Diagnosis of hantavirus is based on a comprehensive evaluation, including the history of high-risk exposure and contact tracing. India has specialised reference laboratories such as the ICMR, National Institute of Virology (NIV), Pune, along with tertiary care centres capable of diagnosing and managing such infections,'' he said. He underlined that the Andes strain ''does not cause large outbreaks like the fast-spreading COVID-19 and will, therefore, not overwhelm hospitals''. On symptoms, Mishra said early signs include ''fever, body aches, fatigue and diarrhoea'', while some patients may rapidly develop lung involvement with breathlessness, low oxygen levels and falling blood pressure after a few days. Dr Rajeev Jayadevan, Co-Chairman of the National IMA COVID Taskforce, said there is no indication of any immediate outbreak risk in India. ''The types of hantaviruses found in India and other parts of the Asian subcontinent are not the same as the ongoing cruise ship outbreak. Hantaviruses in Asia and Europe generally cause kidney disease with lower mortality, unlike the Andes strain, which primarily affects the lungs,'' he said. Dr Jayadevan noted that while asymptomatic exposure to hantaviruses has been documented in India, serious outbreaks have not been reported. ''Climate change and faulty garbage disposal are factors that increase rodent population. However, from India's perspective, leptospirosis remains a far bigger rodent-borne threat,'' he told PTI. Dr Ishwar Gilada, Secretary General of the People's Health Organisation-India and infectious disease expert at Unison Medicare and Research Centre, Mumbai, said hantavirus infections are mainly acquired through exposure to infected rodents or contaminated environments. ''Humans usually become infected through contact with infected rodents or materials contaminated by their urine, droppings, or saliva,'' Gilada said. He explained that infection commonly occurs while cleaning poorly ventilated spaces such as storerooms, garages, warehouses, cabins or ships where contaminated dust particles may become airborne. ''Unlike COVID-19, hantavirus does not spread casually through the air between people. For most strains, human-to-human transmission is either absent or extremely rare,'' he said. Gilada also cautioned that climate change, flooding, rapid urbanisation and poor sanitation could increase long-term risks from rodent-borne diseases. ''Floods and heavy rains often drive rodents into human spaces, while garbage accumulation and overcrowding create ideal conditions for rodent breeding,'' he said. Experts said prevention depends largely on rodent control, sanitation, proper ventilation and avoiding exposure to rodent-infested environments. They stressed that while authorities should maintain surveillance and monitor contacts linked to the cruise ship cases, there is currently no evidence of community transmission or any widespread public health emergency linked to hantavirus in India.