Credit WHO
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A couple of years ago, when film maker Steven Soderbergh made the pandemic thriller `Contagion’, he availed himself of the scientific expertise of epidemiologist Ian Lipkin - director of Columbia University’s Center for Infection and Immunity in New York - who served as technical advisor for the film.
Rather than use a traditional influenza virus for their fictional pandemic, Professor Lipkin painstakingly created a fictional MEV-1 pandemic virus based on a mutated Nipah virus.
As I wrote in The Scientific Plausibility of `Contagion’, while the Nipah virus isn’t currently a pandemic threat - it is possible, that with a few choice mutations in the right places - that could change.
The first known Nipah outbreak occurred in Malaysia in 1998, when the virus infected local swine herds (presumably by bats), and spread to hundreds of people causing the loss over 100 lives. The virus was then exported via live pigs to Singapore, where 11 more people died.
Since then, the Nipah virus – which is normally hosted by fruit bats of the Pteropodidae family – has only sparked limited outbreaks in Southeast Asia, with Bangladesh being the most commonly affected country.
Usually the virus jumps to humans through the consumption of raw (uncooked) date palm juice, which is `tapped’ much in the same way as maple trees are in this country for their syrup.
Bats can roost in these trees and will occasionally contaminate the collected juice with their urine or feces, which each winter leads to stories like the one below from The Daily Star:
Sunday, January 27, 2013
6 died so far of Nipah
Staff Correspondent
Six of the eight people infected with Nipah virus this month have died so far, Institute of Epidemiology, Disease Control and Research (IEDCR) confirmed on Friday.
The dead are from Dhaka, Rajbari, Jhenidah, Naogaon, Natore and Gaibandha.
Yesterday, a man was in a critical condition at a private hospital in the capital.
On January 11, eight of his family drank raw date juice brought from Bhaluka, Mymensingh.
IEDCR Director Prof Mahmudur Rahman said, "Examination of his blood sample confirmed on Wednesday that he was infected with Nipah virus."
His eight-year-old son died of the virus on Tuesday.
Examinations of blood samples of the six others found no evidence of infection.
In Natore, a mother passed away while her eight-month-old baby has been infected.
To date fewer than 200 cases have been reported in Bangladesh, but of those, roughly 75% have died.
While the initial jump to humans is usually associated with drinking raw date juice, once it gets into the human population, it can spread from human-to-human.
How it is transmitted from one person to another isn’t well understood, although it is thought to be mostly through direct contact with respiratory secretions or other bodily fluids.
Nosocomial (in-hospital) transmission has been reported on several occasions.
In 2007 researchers published a study that looked at an outbreak in a Bangladeshi village during 2004, that found evidence of H-2-H transmission.
The following comes from the CDC EID Journal.
Volume 13, Number 7–July 2007
Research
Person-to-Person Transmission of Nipah Virus in a Bangladeshi Community
Emily S. Gurley,Joel M. Montgomery, M. Jahangir Hossain, Michael Bell,Abul Kalam Azad, Mohammed Rafiqul Islam, Mohammed Abdur Rahim Molla, Darin S. Carroll,† Thomas G. Ksiazek, Paul A. Rota, Luis Lowe, James A. Comer, Pierre Rollin, Markus Czub,Allen Grolla, Heinz Feldmann, Stephen P. Luby, Jennifer L. Woodward, and Robert F. Breiman
Abstract
An encephalitis outbreak was investigated in Faridpur District, Bangladesh, in April–May 2004 to determine the cause of the outbreak and risk factors for disease. Biologic specimens were tested for Nipah virus. Surfaces were evaluated for Nipah virus contamination by using reverse transcription–PCR (RT-PCR).
Thirty-six cases of Nipah virus illness were identified; 75% of case-patients died. Multiple peaks of illness occurred, and 33 case-patients had close contact with another Nipah virus patient before their illness. Results from a case-control study showed that contact with 1 patient carried the highest risk for infection (odds ratio 6.7, 95% confidence interval 2.9–16.8, p<0.001).
RT-PCR testing of environmental samples confirmed Nipah virus contamination of hospital surfaces. This investigation provides evidence for person-to-person transmission of Nipah virus. Capacity for person-to-person transmission increases the potential for wider spread of this highly lethal pathogen and highlights the need for infection control strategies for resource-poor settings.
While most human infections present with encephalitic symptoms, those few who develop respiratory difficulties appear to be the ones most able to infect others – raising the possibility of large-droplet transmission.
The World Health Organization has this to say about limiting transmission of the virus in their NIPAH VIRUS FAQ.
Reducing the risk of infection in people
In the absence of a vaccine, the only way to reduce infection in people is by raising awareness of the risk factors and educating people about the measures they can take to reduce exposure to the virus.
Public health educational messages should focus on the following.
- Reducing the risk of bat-to-human transmission. Efforts to prevent transmission should first focus on decreasing bat access to date palm sap. Freshly collected date palm juice should also be boiled and fruits should be thoroughly washed and peeled before consumption.
- Reducing the risk of human-to-human transmission. Close physical contact with Nipah virus-infected people should be avoided. Gloves and protective equipment should be worn when taking care of ill people. Regular hand washing should be carried out after caring for or visiting sick people.
- Reducing the risk of animal-to-human transmission. Gloves and other protective clothing should be worn while handling sick animals or their tissues, and during slaughtering and culling procedures.
Controlling infection in health-care settings
Health-care workers caring for patients with suspected or confirmed Nipah virus infection, or handling specimens from them, should implement standard infection control precautions.
Samples taken from people and animals with suspected Nipah virus infection should be handled by trained staff working in suitably equipped laboratories.
Over the past 15 years bats have been linked to outbreaks of Nipah, Hendra, and SARS-CoV in humans and are `suspected’ to be at least one of the reservoirs for the Ebola and Marburg viruses.
In 2012, for the first time a `bat influenza virus’ was discovered (see A New Flu Comes Up To Bat), and the newly detected novel coronavirus from the Middle East - EMC/2012 – has been tentatively linked to bats as well (see EID Journal: EMC/2012–related Coronaviruses in Bats).
Although most researchers expect the next pandemic to come from a swine or avian influenza, other pathogens carried by different species cannot be ignored.
With the exception of the SARS outbreak of 2002-2003, bat-borne pathogens have not produced any large-scale human epidemics (that we know of).
But viruses have a habit of changing and evolving over time, making the monitoring of even small outbreaks of relatively rare infectious diseases of more than just academic interest.
For more on bats, and bat-hosted viruses, you may wish to revisit:
EID Journal: Ebola Virus Antibodies From Bats In Bangladesh
Disease Transmission At The Human-Animal Interface
Coronavirus `Closely Related’ To HK Bat Strains
Virology Journal: Ebola Virus In Chinese Bats
