Credit WHO
# 6966
Hendra Virus (HeV) and Nipah Virus (NiV) are a pair of closely related members of the family known as Paramyxoviridae that can infect a wide range of hosts, including mammals, birds, and fish.
The Paramyxoviridae family includes such diverse viruses as aquaparamyxovirus that infect salmon, Newcastle disease for poultry, Morbilliviruses which include measles, rinderpest virus & canine distemper, and human RSV respiratory syncytial virus.
Hendra and Nipah, both discovered in the last decade of the 20th century, are sufficiently different from other members of the Paramyxoviridae family to have led to the creation of a new genus; Henipavirus.
Their host species are fruit bats, where they seem to reside with little ill effect. Unfortunately, when they spillover into other species, they can be quite deadly.
Both are considered biosecurity level 4 (BSL-4) pathogens.
Hendra first came to light after the deaths of 13 horses and a trainer in Hendra, a suburb of Brisbane, Australia in 1994. A stable hand, who also cared for the horses, was hospitalized, but survived.
Another outbreak was later identified as having taken place in MacKay, 1000 km to the north of Brisbane, the month before. Two horses died, and the owner was hospitalized several weeks later with meningitis. He recovered, but developed neurological symptoms and died 14 months later.
Over the past 18 years more than 40 outbreaks of Hendra virus – all involving horses – have been reported in Australia. At least four human fatalities have been linked to the virus as well.
Of the two, Nipah has been the deadliest, causing outbreaks primarily in India and Bangladesh. But the virus was first discovered in April of 1999 when an outbreak occurred at a pig farm in Malaysia.
During this initial outbreak, the virus jumped to local swine herds from bats, and infected more than 250 people, killing more than 100. The virus was then exported via live pigs to Singapore, where 11 more people died (see MMWR Update: Outbreak of Nipah Virus -- Malaysia and Singapore, 1999)
Over the past decade, Nipah has sparked a handful of smaller outbreaks across Southern Asia with the greatest activity centered around Northern India and Bangladesh.
Earlier this month, in Bangladesh: Updating The Nipah Outbreak, we looked at their latest outbreak, which at that time had infected 11 and killed eight.
Seasonal Nipah infections (Dec-May) have been linked to the consumption of raw (uncooked) date palm juice - which is `tapped’ from cuts in trees much in the same way as maple trees are for their syrup. Bats roost in these trees at night, and can easily contaminate the collection jars with urine or feces.
But this isn’t necessarily a dead end infection for Nipah, as humans can spread the virus amongst themselves as well (see EID Journal Person-to-Person Transmission of Nipah Virus in a Bangladeshi Community).
Today, an update from Bangladesh’s Institute of Epidemiology Diseases Control and Research (IEDCR), that brings the total number infected to 16, and the total number of deaths to 14.
Nipah Infection in 2013
Situation Update:
23 February 2013: 16 Nipah cases were identified among them 14died (mortality rate 88%); 2 cases are still under treatment. These cases are from 11 districts (Gaibandha, Natore, Rajshahi, Naogaon, Rajbari, Pabna, Jhenaidah, Mymensingh, Nilphamari). Age distribution of cases are 8 months to 55 years among them 11 are male.
Nipah
Human Nipah virus (NiV) infection, an emerging zoonotic disease, was first recognized in a large outbreak of 276 reported cases in Malaysia and Singapore from September 1998 through May 1999.
Agent
NiV is a highly pathogenic paramyxovirus belonging to genus Henipavirus. It is an enveloped RNA virus.
Incubation period
The median incubation period of the secondary cases who had a single exposure to Nipah case was nine days (range 6–11 days) but exposure to onset of illness varies from 6-16 days. The median incubation period following single intake of raw date palm sap to onset of illness is 7 days (range: 2-12 days) in Bangladesh.
Transmission:
- Drinking of raw date palm sap (kancha khejurer rosh) contaminated with NiV
- Close physical contact with Nipah infected patients
Surveillance
Nipah surveillance began in 2006, Institute of Epidemiology, Disease Control and Research (IEDCR) in collaboration with ICDDR,B established Nipah surveillance in 10 District level Government hospitals of the country where Nipah outbreaks had been identified. Presently surveillance system is functioning in five hospitals of Nipah Belt.
Meanwhile, in Queensland, Australia a fresh horse death from Hendra is in the news, with four people who may have been exposed under observation. This from Queensland BioSecurity.
New Hendra virus case confirmed in North Queensland
News release | 22 February, 2013
Biosecurity Queensland is managing a new Hendra virus case in the Tablelands area after a positive test result was received late last night.
Queensland Chief Veterinary Officer Dr Rick Symons said one horse had died on the property after becoming unwell over the weekend.
"Biosecurity Queensland is in the process of quarantining the property. There are other horses on the property and we will be working to determine what contact the infected horse had with these other animals," Dr Symons said.
"Testing and monitoring will then be undertaken over the next month.
"While under quarantine, restrictions will apply to moving horses and horse materials on and off the infected property."
An initial assessment from Queensland Health's Public Health Unit in Cairnshas identified four people who had contact with the infected horse.
Public health staff are now interviewing these people to determine whether any testing or treatment is required. All four people are thought to have had a low level of exposure to the infected horse.
Queensland's Chief Health Officer Dr Jeannette Young reassured the community that transmission of the virus required close contact with body fluids of the sick horse.
"There is no evidence the virus can be passed directly from flying foxes to humans, from the environment to humans, from humans to horses, or can be transmitted by airborne droplets," Dr Young said.
"Anyone who is concerned should contact 13 HEALTH (13 43 25 84).
"We stand ready to provide any assistance, counselling, information, testing or treatment that may be required."
Dr Symons said this was the second case of Hendra virus in Queensland this year.
Nipah and Hendra are non-segmented, single-stranded negative-sense RNA viruses, and as such, are subject to a fairly high rate of mutation.
A couple of years ago, when film maker Steven Soderbergh made the pandemic thriller `Contagion’, Professor Ian Lipkin - director of Columbia University’s Center for Infection and Immunity in New York – based its fictional MEV-1 virus on a mutated Nipah virus.
As I wrote in The Scientific Plausibility of `Contagion’, the Nipah virus isn’t currently a pandemic threat - and for now - shows no signs of becoming one.
But some scientists worry that with a few choice mutations in the right spot in its genome, that status could one day change. So we watch these dramatic, albeit rare, spillovers of Nipah and Hendra from bats closely, for any signs of a greater threat.
