What are the symptoms of hantavirus infection and it is an issue in Australia?
Hantavirus, a serious disease transmitted by rodents, hit the news following the sad death of Betsy Arakawa, the wife of actor Gene Hackman. Investigations into her death suggested that she died at home from undiagnosed hantavirus pulmonary syndrome. So, what is hantavirus, what are the symptoms of infection, and it is an issue in Australia?
There are over 50 species of hantavirus (also called orthohantavirus), of which 24 are known to cause disease in humans. The different hantaviruses can cause one of two distinct forms of the disease – haemorrhagic fever with renal syndrome (HFRS) or hantavirus cardiopulmonary syndrome (HCPS). Generally speaking, HFRS is caused by hantaviruses found in Europe and Asia, with HCPS restricted to North and South America.
There is limited data on hantaviruses in Africa and to date hantavirus has not been detected in any rodents in Australia and New Zealand. However, that’s not to say it doesn’t exist in Australia and New Zealand.
The symptoms of hantavirus infection depend on the type of virus. As its name suggests, HFRS causes bleeding from various areas of the body with varying effects on kidney function. HCPS impacts both lung and heart function, leading to breathing difficulties and heart arrhythmia.
Around 150,000-200,000 cases of hantavirus disease occur each year, with the majority being HFRS, and the majority of these being in Asia. Hantavirus is a life-threatening disease, with mortality rates from HFRS ranging from 5-15% and mortality from HCPS being nearer 40%.
One of the challenges in diagnosing hantavirus infection is that it can have a long incubation period (up to eight weeks) and it often presents initially as flu-like symptoms (fever, headache, nausea, muscle pains). This often leads to misdiagnosis and a delay in getting life-saving treatment. In addition, there are some mild forms of HFRS that probably don’t even get diagnosed as hantavirus, so global incidence figures are probably an underestimation.
Currently, there is no vaccine or cure for hantavirus infection, meaning patient treatment focuses on symptom management.
It is not known how Ms Arakawa contracted the disease, but hantavirus is most commonly picked up by inhaling rodent faeces, urine or saliva, which can be inhaled when cleaning up rodent droppings or handling nesting material. It is possible to get transferred if bitten or scratched by an infected rodent. Therefore, it is important to follow best practice rodent mess cleaning and rodent handling procedures to prevent transmission of hantavirus (and a range of other rodent diseases, such as leptospirosis and rat-bite fever):
- Always wear gloves when cleaning up after a rodent infestation or handling rodents
- Wear a mask when cleaning up rodent mess
- Avoid sweeping or vacuuming, which can push infected dust into the air
- Spray areas to be cleaned with disinfectant and leave for five minutes before cleaning up areas with paper towels or cloths
- Disposed of any cleaning items after use
- Thoroughly disinfect infected areas again after cleaning
While each hantavirus species tends to be specific to a limited number of rodent partners – for example the Sin Nombre virus, which is common in North America – is carried by the deer mouse, it is the hantaviruses that could be carried by the main global pest rodents (Norway rat, roof rat and house mouse) that could have the biggest potential for global spread. The Seoul orthohantavirus (SEOV) in the Norway rat is a hantavirus that is receiving closer attention, partly because it is also carried in pet and laboratory rats.
Although SEOV is a frequently diagnosed strain in Asian hantavirus cases, the low number of cases reported in Europe and the US does not appear to make sense, given the main carrier of SEOV is the Norway rat, which is found globally. The reasons for the limited number of cases outside of Asia is not yet known, although part of the reason for this could be that it causes a milder form of HFRS, sometimes even lacking kidney symptoms, so doesn’t get correctly diagnosed.
However, positive antigen test results on wild Norway rats have shown that hantavirus, probably SEOV, does indeed appear to be present in Norway rat populations on all continents. Which means that although the virus itself hasn’t been detected in Australia and no human cases have been reported, hantavirus is probably present in Australia.
So, pest managers and indeed anyone cleaning up after a rodent infestation or handling rodents, must assume there is potential for transmission of one of a range of potential diseases. Whether or not hantavirus is one of them, the precautions are the same.
Clement, J et al. (2019). Wild Rats, Laboratory Rats, Pet Rats: Global Seoul Hantavirus Disease Revisited. Viruses, 11(7): 652
