Nipah Virus: An Emergent Deadly Paramyxovirus Infection In Bangladesh

Abstract

Nipah virus, a member of the genus Henipavirus, a new class of virus in the Paramyxoviridae family, has drawn attention as an emerging zoonotic virus in south east and south asian region. Case fatality rate of Nipah virus infection ranges from 40-70% although it has been as high as 100% in some outbreaks. Many of the outbreaks were attributed to pigs consuming fruits partially eaten by fruit bats, and transmission of infection to humans. In Bangladesh, 7 outbreaks of Nipah virus infection were identified during the period 2001-2007. In Bangladesh, Nipah virus infection was associated with contact with a sick cow, consumption of fresh date palm sap (potentially contaminated with pteropid bat saliva), and person-to-person transmission. In the most recent epidemic at least 15 people died due to Nipah virus infection in Hatibandha, Lalmonirhat district in a remote northern Bangladesh town in 2011 adding to the previous death toll of 113 in the country . Human infections range from asymptomatic infection to fatal encephalitis. Infected people initially develop influenzalike symptoms of fever, headaches, myalgia , vomiting and sore throat. This can be followed by dizziness, drowsiness, altered consciousness, and neurological signs that indicate acute encephalitis. Some people can also experience atypical pneumonia and severe respiratory problems. The virus is detected by ELISA, PCR, immunofluoroscent assay and isolation by cell culture. Treatment is mostly symptomatic and supportive as the effect of antiviral drugs is not satisfactory, and an effective vaccine is yet to be developed. So the very high case fatality addresses the need for adequate and strict control and preventive measures.

Nipah Virus

“…The case fatality rate estimates remain ~40-100% during sporadic outbreaks (Table 1). Most people who survive acute encephalitis make a full recovery, but around 20% are left with residual neurological consequences such as persistent convulsions and personality changes [42,47]. A limited number of recovered patients may experience encephalitic relapse up to years later and subclinically infected individuals may show central nervous signs up to 4 years later.…”

Controlling Nipah virus encephalitis in Bangladesh: Policy options

“…3 In Western Bangladesh, NiV was first identified in April/May 2001 in an encephalitic outbreak with high case fatality (9 out of 13). 4 A second outbreak in Bangladesh occurred in January 2003, during which 8 people died (out of 12). 4 Traceback information suggested two risk factors: climbing date palm trees and close association with patients.…”

“…4 A second outbreak in Bangladesh occurred in January 2003, during which 8 people died (out of 12). 4 Traceback information suggested two risk factors: climbing date palm trees and close association with patients. 5 In 2004, 49 deaths (out of 65 cases) were reported in a third outbreak in two separate communities.…”

“…5 In 2004, 49 deaths (out of 65 cases) were reported in a third outbreak in two separate communities. 4 It was found to be a result of direct or indirect contact with fruit bats, including date palm sap (DPS) consumption. 6 During a subsequent outbreak in 2005, researchers established a significant relationship between the consumption of raw date farm syrup contaminated by fruit bat saliva and NiV infection (11 out of 12 cases died).…”

“…6 During a subsequent outbreak in 2005, researchers established a significant relationship between the consumption of raw date farm syrup contaminated by fruit bat saliva and NiV infection (11 out of 12 cases died). 4 Between 2001 and 2012, 280 cases of Nipah or Nipah-like virus encephalitis were identified, with 211 deaths (case fatality rate of 75 per cent). 7 NiV appears to be increasingly virulent in Bangladesh, with greater case fatality rates each year, peaking at 100 per cent in 2011 and 2012.…”