Hendra virus and Nipah virus (Henipavirus) Infections were first identified in the 1990s as the cause of respiratory and neurological conditions in humans and animals. In 1994, Hendra virus related severe respiratory infections were first reported in horses in Queensland and New South Wales, Australia, resulting in more than 80 horses that died from the infection or that had to be euthanized. Flying foxes (fruit bats) of the genus Pteropus are the natural Hendra virus reservoir hosts, which is transmitted to horses through indirect contact via contaminated fruits. To date, four humans (horse trainers and veterinarians) were infected through contact with affected horses, and four of these infections were fatal. Since 2012, a recombinant vaccine has been available for the vaccination of horses in Australia, which is based on the Hendra virus attachment glycoprotein. This allows a DIVA (Differentiating Infected from Vaccinated Animals) based serological diagnose, as vaccinated horses generate antibodies only against the glycoprotein, while in the serum of infected horses, antibodies against the Hendra virus nucleoprotein will also be detectable.
Between September 1998 and April 1999, Nipah virus spread undetected as the cause of respiratory and encephalitic infection in pigs in Malaysia and Singapore, and then manifested itself as fatal encephalitis in humans, when human infections occurred after contact to infected pigs with more than 100 human fatalities (mortality > 30%). More than a million pigs were culled in Malaysia as part of the control measures that followed. Here, too, Pteropus fruit bats were identified as the reservoir hosts, and transmission to pigs also occurred via contaminated fruits. Since then, recurring Nipah virus infections have been reported in Bangladesh and India, where the virus is transmitted to humans through direct or indirect contact to fruit bats, without the involvement of pigs in the transmission chain. Here, mortality rates of in some cases even significantly higher than 70% are observed. Due to this development, Nipah virus has been added to the blueprint list of prioritized and particularly dangerous pathogens by the World Health Organization (WHO) in 2018.
In order to be able to process sample submissions, e.g. from export animals or animals suspected of being infected, real-time RT-PCR protocols have been established at the National Reference Laboratory, which allow the detection of the N gene of Hendra or Nipah virus. In addition, serological in-house methods have been developed that enable the detection of Hendra or Nipah virus specific antibodies according to the DIVA principle. In the high-security laboratory there is also the possibility of carrying out a virus neutralization test or a virus cultivation experiment for reactive samples.