Following a recent outbreak in India, Nipah virus remains a significant global health concern. While not currently present in Australia, researchers at the CSIRO are actively studying the virus and related pathogens to bolster national preparedness and enhance understanding of emerging viral threats. This research includes the recent discovery of a new bat-borne virus, Salt Gully virus, highlighting Australia’s ongoing focus on this family of high-consequence pathogens.
What is Nipah Virus?
Nipah virus is a zoonotic virus, meaning it spreads from animals to humans, capable of causing severe respiratory illness and fatal brain inflammation, known as encephalitis. First identified in 1998, We see considered a dangerous emerging infectious disease due to its high fatality rate and the current lack of approved treatments or vaccines.
Dr. Sarah Edwards, Group Leader – Zoonotic Pathogens and Models at CSIRO, explains that while Nipah virus isn’t currently circulating in Australia, closely related viruses, such as Hendra virus, are present. Hendra virus is carried by Australian flying foxes and can spillover from bats to horses, and subsequently to humans. Currently, there is no evidence of direct transmission of Hendra virus from bats to humans.
Current Outbreak and Viral Strains
Outbreaks of Nipah virus occur almost annually in parts of Asia, most frequently in India, and Bangladesh. According to Dr. Edwards, the current outbreak in India is not caused by a new strain of the virus, but it is occurring in West Bengal, an area that hasn’t experienced cases in nearly 20 years.
While the viruses reported in Bangladesh and India are closely related, they differ in how spillover occurs. In Bangladesh, cases are often seasonal and linked to the consumption of contaminated sap from date palms. In India, outbreaks are less frequent and typically linked to healthcare settings – spread between patients or healthcare workers – or exposure to bats.
How is Nipah Virus Transmitted?
Ms. Jenn Barr, experimental scientist and leader of the Pathogen Investigation team at CSIRO, details several established transmission pathways. Animal-to-human transmission occurs through direct contact with infectious bodily secretions, such as saliva, urine, or feces, from fruit bats or infected intermediate hosts like pigs.
Contaminated food also plays a role, particularly date palm sap consumed by bats. In Bangladesh, bats often drink from or lick date palm sap collection pots, contaminating the sap and creating a route for human infection. Person-to-person transmission occurs through close contact with an infected individual or their bodily fluids.
Risk to Australia
As of , there have been no recorded outbreaks of Nipah virus in Australia. Ms. Barr states it is highly unlikely that animals or people in Australia will be affected by the current outbreak, as the virus doesn’t spread easily and requires close, prolonged contact with infected individuals.
Nipah virus is rare, with isolated outbreaks almost exclusively in Bangladesh and India. Despite its high fatality rate, the virus spreads poorly between people and lacks airborne transmission, meaning outbreaks tend to remain localized and are usually contained with existing public health measures.
CSIRO’s Nipah Virus Research
CSIRO’s Australian Centre for Disease Preparedness (ACDP) facility has been researching Nipah virus since the initial outbreak in 1998. This research encompasses the development of diagnostic tests for early detection, understanding the virus’s mechanisms and why it is so deadly, creating testing models to study viral behavior, and conducting early-stage studies to evaluate potential vaccines and therapeutics. Field surveillance is also conducted both domestically and internationally.
Safe Virus Study at CSIRO’s ACDP
Dr. Edwards emphasizes that all work with Nipah virus must be conducted in a Biosafety Level 4 laboratory, the highest biosafety level globally. Pathogens requiring this level of containment cause severe or fatal disease and have no licensed vaccines or therapeutics. Scientists at ACDP undergo extensive biosafety training and wear fully encapsulating suits when researching dangerous viruses like Nipah and Hendra.
Why Bats and Viral Transmission?
Ms. Barr explains that bats don’t necessarily carry more diseases than other animals, but some of the viruses they host can be particularly harmful to humans. Spillover events are often driven by human activities, such as habitat loss, which forces wildlife into closer contact with people and livestock. Healthy, intact ecosystems help buffer against the emergence of new diseases.
Ms. Barr further explains that bats often avoid the damaging inflammatory responses that occur in humans when infected with a virus. Their immune systems suppress pathways that would otherwise trigger inflammation, and some components of the Australian flying fox immune system are already active before infection, giving them an early advantage.
What to Do if You Encounter a Sick or Trapped Bat
Ms. Barr advises against handling bats, as they can carry Australian bat lyssavirus, which can be transmitted through a bite or scratch. If you encounter an injured or distressed bat, contact a wildlife rescue organization, who can arrange for a vaccinated and trained rescuer to assist.
