Nipah virus (NiV), belongs to the genus Henipa Virus of the Paramyxoviridae family, categorized as zoonotic biosafety level 4 (BSL4) agent, and is believed to cause 40 – 100% mortality in human/ animals. It is known to cause a wide variety of infections among animals/humans, is a notifiable disease of importance and has caused severe outbreaks in the recent past.
This virus is inactivated at 600C for 60 min and stable at pH 4-10. Under favorable conditions, it can survive for days in the urine (bat) and contaminated fruit juices. NiV is sensitive to common soaps and disinfectants like alcohol and Sodium hypochlorites.
This organism can cause infection in humans, bats, pigs, dogs, cats, and horses. Naturally, NiV is transmitted through bats (Fruit bats) in Asian countries, especially in Malaysia, India, Australia and some of the tropical countries. Microbiological experiments have proved the presence of NiV in the secretions, urine and tissue samples of these bats.
In history, the first time this NiV has been reported from ‘Sungai Nipah’ a village in Malaysia in 1998 causing encephalitis infection in 285 cases with a case fatality of 40%. Later it was reported from Singapore (1999), India (2001, 2007, 2018-19), Bangladesh (2001,03,04,05,07,08,09,2010-14) causing 9-92% case fatality in the outbreaks. Now some districts of Bangladesh have considered this disease as endemic areas for NiV infections. Epidemiologists reported the close association between mango fruits, Pigs and bats. These observations further proved by microbiological investigations, which showed the presence of viral specific antibodies in the bats, fruit juices and in pigs.
The transmission of NiV occurs through direct contact with sick pigs and consumption of fruits which are contaminated with urine/ saliva of infected bats. Recent outbreaks have shown human to human infections through close contact with infected patients in the hospital, especially among the relatives and in the hospital faculty. The incubation period for NiV infection is four days to 15 days. The infected patients initially present with high-grade fever, myalgia, headache, sore throat, weakness are followed by symptoms of systemic involvement ( of gastrointestinal, Respiratory, renal and even Central Nervous systems), including respiratory distress, septicemia, GI bleeding, Renal impairment and encephalitis. The case fatality ranges from 40-100% and people survived will have residual neurological consequences.
The diagnosis of NiV infection requires BSL4 level precautions, which includes, special precautions even during the collection of clinical samples from patients with physical containment level 4 (PC4). The clinical samples further tested for evidence of NiV by Molecular (Real Time PCR), serological and viral cell culture techniques.
Presently there is no specific treatment and vaccines are available for this infection. Clinicians and epidemiologist recommended preventive measures of these NiV infections including; a) reducing the risk of the bat to human transmission, b) reducing the human to human transmission and c) prevention of consuming contaminated food and fruits. Increasing the awareness and information about such infections among the farmers and related occupation including medical specialties. General preparedness of Health care facilities to take up proper and immediate actions against such infections will definitely control the outbreaks among the public.
Dr. Mahantesh B Nagmoti, · MD (Micro) Ph.D (Med Micro)
Department of Microbiology, Jawaharlal Nehru Medical College, Belagavi