- Ribavirin, an antiviral, may have a role in reducing mortality among patients with encephalitis caused by Nipah virus disease
- All Nipah outbreaks in India and Bangladesh occurred during December-May, indicating a certain seasonality to it
After one year, Kerala is again under a threat of the deadly Nipah virus (NiV) infection. Pune’s National Institute of Virology (NIV) on Tuesday confirmed a suspected case in the state as an NiV infection. Mint goes behind the reasons for the rise in the NiV cases, the origin and the symptoms.
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What is Nipah virus?
Human Nipah virus (NiV) infection is an emerging zoonotic disease which was first recognized in a large outbreak of 276 reported cases in Malaysia and Singapore from September 1998 to May 1999. The first identification of Nipah virus as a cause of an outbreak of encephalitis was reported in 2001 in Meherpur district of Bangladesh. There is circumstantial evidence of human-to-human transmission in India in the same year. During the outbreak in Siliguri, 33 health workers and hospital visitors became ill after exposure to patients hospitalized with Nipah virus illness. Nipah cases tend to occur in a cluster or as an outbreak.
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How does the virus spread?
The virus can travel from infected bats to pigs to humans or directly to humans from bats. Large fruit bats of Pteropus genus are the natural reservoir of NiV. Presumably, pigs may become infected after consumption of partially bat eaten fruits that are dropped in pigsties. All outbreaks in India and Bangladesh occurred during December-May, indicating a certain seasonality to it. The incubation period may vary from 6-21 days. Transmission of Nipah virus to humans can also happen from infected people through close physical contact, especially by contact with body fluids. Transmission through drinking of raw date palm sap, contaminated by bat urine or saliva, has also been identified.
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What explains the rising cases of the disease?
Environmental experts claim that Nipah virus has existed in the bats for centuries and this virus has not undergone an evolutionary change, but the rapid rise in the spread of the infection begs a study. Many ecological factors have contributed to the emergence of the Nipah virus. The most prominent is human intervention in the bat-infested areas due to rapid urbanization. In Malaysia, the virus spread due to unplanned deforestation of pulp wood, which is the natural habitat for NiV carrying bats, and mismanagement of large piggeries.
What are the symptoms of the Nipah virus disease?
Nipah virus causes severe illness characterized by inflammation of the brain (encephalitis) or respiratory diseases. Other symptoms are fever, altered mental status, severe weakness, headache, respiratory distress, cough, vomiting, muscle pain, convulsion and diarrhea in infected people in general. The case-fatality rate is estimated at 40-75%; however, this rate can vary by outbreak and can be up to 100%. Laboratory diagnosis of a suspected patient can be made by using a combination of tests. In India, testing facility is available at NIV, Pune.
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What is the treatment of Nipah virus disease?
Currently there is no known treatment or vaccine available for either people or animals and treatment is limited to supporting care. Nipah virus is one of the pathogens in the WHO Research & Development (R&D) blueprint of epidemic threats needing urgent R&D action. However, Ribavirin, an antiviral, may have a role in reducing mortality among patients with encephalitis caused by Nipah virus disease. Intensive supportive care with treatment of symptoms is the main approach to managing the infection in people.
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