ANN/THE STAR – Recent reports of Nipah virus (NIV) infections in Kerala, India have drawn global attention.
Since first reported on August this year, there have been six cases, two casualties, as of September 23. Over 700 healthcare workers tested in the past week.
The deadly microorganism is a zoonotic virus, which spreads from animals to humans. It can also spread through contaminated food or directly between people.
The first global outbreak occurred in Malaysia in 1998-1999. The initial NIV cases occurred near Ipoh, Perak, in September 1998, with the Health Ministry then declaring it a Japanese B encephalitis outbreak.
The infected swine were transferred to Bukit Pelandok, Negri Sembilan, leading to NIV spreading to the population of swine there, which then infected swine farmers.
This resulted in the near decimation of the local swine-rearing industry, which was then Asean’s largest, with about a million swine culled.
The outbreak was reported to have eventually affected 283 people, of which 109 died – a case fatality rate of 38.5 per cent.
An NIV outbreak (11 cases, one death) was also reported in Singapore among slaughterhouse workers in March 1999. An outbreak occurred in Bangladesh in 2001, following which there have been nearly annual outbreaks there.
NIV outbreaks have also occurred in eastern India and Kerala state since 2001. The current outbreak is the fourth outbreak in Kerala in the past five years.
HOW IT SPREADS
Most human infections in Malaysia resulted from direct contact with sick swine or their contaminated tissues.
Transmission was thought to have occurred from unprotected exposure to swine secretions, or unprotected contact with the tissue of sick swine.
In Bangladesh and India, the consumption of fruits or fruit products contaminated with urine or saliva from infected fruit bats was the most likely source of infection.
Human-to-human transmission has been reported among family members and caregivers of those infected.
Hospital staff or visitors were affected in three-quarters of the cases in Silguri, West Bengal, India, in 2001.
About half of the reported cases in Bangladesh from 2001-2008 were due to human-to-human transmission through provision of care to the infected.
The natural host of NIV are fruit bats found in Australia, Bangladesh, Cambodia, China, India, Indonesia, Madagascar, Malaysia, Papua New Guinea, Thailand and Timor-Leste.
The fruit bats themselves exhibit no apparent disease from the virus.
NIV is also found in domestic animals like swine, horses, goats, sheep, cats and dogs, as was first reported in the Malaysian outbreak in 1999.
NIV should be suspected if swine have an unusual barking cough or if there are human cases of encephalitis. – Dr Milton Lum
