Hantavirus outbreaks have recently been reported in a number of regions around the world, which has led researchers and health officials to investigate possible climate links that may be responsible for the outbreaks. There are hantaviruses which can be transmitted by rodents, and although rodents do not usually cause human disease, there have been cases of severe illness, including Hantavirus Pulmonary Syndrome (HPS), in humans following exposure to these viruses if the exposure period is prolonged and the treatment is delayed. 

Infections in humans usually result from contact with infected droppings and urine from rodents, or from human exposure to contaminated dust with rodent urine, droppings or saliva (often stirred up in enclosed spaces). Human infections are usually reported where the population is in contact with wild rodents in a rural or forested setting. Recent reports, however, have revealed some atypical trends in the timing and distribution of outbreaks, prompting some further investigation of environmental changes. 

Another supposition is that the warmer the temperature and the more different the precipitation, the more climate change could be having an impact on rodent populations, their reproductive cycles and their relationship to human habitats. Warm winter weather can result in lower rodent deaths and make populations larger than normal. Similarly, fluctuations in available food resources can result from an increase in precipitation or from a low rate of precipitation, pushing rodents into houses searching for food. 

Climate is only one of many factors that might affect hantavirus transmission, warn scientists. Land use practices, including deforestation, agricultural expansion and urban sprawl, may displace rodent habitats and create human-rodent interaction. Risk is further caused due to poor housing, lack of sanitation and low-level public awareness. 

Prevention is largely about 'washable' public health strategies, according to public health officials. They include sealing homes and workplaces to exclude any rodent entry points, proper storage of food and waste products, placement of clean spaces where rodents cannot enter and have stored rodent problems, and proper ventilation when cleaning areas where rodents have stored problems.