Editor's Note: The recent hantavirus infection event on an international cruise ship has drawn widespread concern. To help the public understand the virus and avoid unnecessary fear, this article presents insights from Professor Li Dongzeng, chief physician at the Department of Infectious Diseases, Beijing You An Hospital, Capital Medical University. He addresses the most pressing questions about hantavirus transmission, clinical presentation and preventive measures, offering authoritative and practical health guidance.

Recent years have seen frequent outbreaks of zoonotic diseases, including hantavirus and dengue. The core reason is an imbalance between human activity and the natural ecosystem. Three major drivers – global warming, ecological change, and urbanization – interact to accelerate the spillover of animal-borne viruses to humans.

First, rising global temperatures and more frequent extreme weather events (heatwaves, droughts and heavy rains) are expanding the habitat range of rodents, the natural hosts of hantavirus. This breaks through previous geographic boundaries. For example, the Andes virus (ANDV), a hantavirus strain once limited to South America, is spreading to new areas as rodents migrate, increasing human exposure and thus the risk of infection. 

Warming also thaws glaciers and permafrost, potentially releasing ancient pathogens. Higher temperatures can prolong viral survival outside the host, accelerate viral replication in hosts, and enhance virulence. For instance, during El Niño events, the risk of large influenza outbreaks may change, and unusual winter temperature fluctuations can lead to more severe flu seasons the following year – a pattern that also applies to hantavirus and other zoonotic diseases. 

According to China's National Climate Center, the equatorial central-eastern Pacific is expected to enter an El Niño state in May 2026, forming a moderate-to-strong El Niño event in summer and autumn, which could increase infectious disease transmission risks.

Second, human activities such as deforestation, habitat destruction, and pollution disrupt natural ecological balances. Rodents and other virus hosts are forced to move into human-dominated areas (such as cities and farmland), increasing opportunities for contact. At the same time, biodiversity loss breaks viral transmission chains. Viruses once confined to animals can more easily cross species barriers and infect humans. In the case of hantavirus, when rodents enter human living and working spaces, their excreta contaminate the environment, leading to human infection.

Third, rapid urbanization leads to higher population density. In older urban neighborhoods, urban villages, suburban farmhouses and similar areas, rodent breeding can occur easily, creating potential hantavirus transmission sites. 

Furthermore, frequent international travel and trade allow viruses to cross geographic borders quickly from endemic to non-endemic regions. The recent MV Hondius cruise ship outbreak is a classic example – a traveler infected through exposure in a South American endemic area boarded the ship, causing limited transmission in an enclosed environment and involving multi-country contact tracing, which complicates outbreak control. 

According to public research, out of 375 known human pathogenic diseases, 218, including hantavirus infection, are worsened by climate disasters, while urbanization further amplifies this risk.

(Cover: A laboratory technician uses a micropipette, Cordoba, Argentina, May 13, 2026. /VCG)