Nipah Virus Disease

NIPAH VIRUS DISEASE 

Nipah Virus Infection (NiV) is recently in news all over India and world because of the recent outbreaks in Kozhikode, Kerala, India. Nipah Virus is a newly emerging zoonosis that causes a severe disease in both animals and humans.

The name Nipah named after the name of a village in Malayesia, where the virus was isolated first.

Nipah Virus is a RNA virus of the genus Henipavirus  causes zoonotic disease- Nipah Virus Infection (NiV). The organism which causes Nipah Virus encephalitis is an RNA or Ribonucleic acid virus of the family Paramyxoviridae, and is closely related to Hendra virus.

HISTORY

In 1998 : NiV was first identified during an outbreak of disease that took place in Kampung Sungai Nipah, Malaysia in 1998. In 1998-99, 265 people were affected in Malayesia and Singapore with 105 death.

In 2001 : Nipah virus was reported from Meherpur District, Bangladesh  and Siliguri, India.  In 2001 The There is an ongoing outbreak in Kerala, India, with ten recorded deaths, including a healthcare worker

In 2004-5: outbreak again appeared in Naogaon District, Manikganj District, Rajbari District, Faridpur District and Tangail District. In Bangladesh, there were outbreaks in subsequent years as well.

In 2007 : A second outbreak was reported in 2007 in Nadia district of West Bengal. 5 positive cases for NiV , all died.

In 2018 : Recent outbreak in Kerala already took 10 lives up to 20.5.18. Other nine persons are currently undergoing treatment and isolation wards have been opened in several hospitals in Kozhikode.

HOST AND TRANSMISSION

As quoted by the WHO, the natural host of the virus are fruit bats of the Pteropodidae Family, Pteropus genus. It first appeared in domestic pigs and has been found among several species of domestic animals including dogs, cats, goats, horses and sheep.

In Malaysia NiV was first transmitted to pigs and from pigs to humans, however in Bangladesh and India NiV travelled directly from bats to humans.

In India and Bangladesh it has been found that the virus spreads through the consumption of date palm sap that is contaminated by bat urine or saliva.

Furthermore, transmission between farms may be due to fomites – or carrying the virus on clothing, equipment, boots, vehicles.

INCUBATION PERIOD

Incubation period is the time interval between entry of disease pathogen (virus) into the body and appearance of symptom. In case of Nipah virus it is 3-14 days.

SIGNS AND SYMPTOMS

Nipah Virus is usually associated with inflammation of the brain

1.      Initial symptoms are fever, headache, drowsiness, nausea, dizziness followed by disorientation and mental confusion. These symptoms can progress into coma as fast as in 24–48 hours. Encephalitis is the dreaded complication of nipah virus infection.

2.      Respiratory illness can also be present during the early part of the illness.

3.      These symptoms can last up to 7-10 days. Watching out for respiratory illness during the early stages is also a must.

4.      The disease is suspected in symptomatic individuals in the context of an epidemic outbreak.

During the outbreak in Malaysia, up to 50 per cent of clinically apparent human cases died

DIAGNOSIS

Laboratory diagnosis of Nipah virus infection is made using

1.      Real time polymerase chain reaction( rt-pct) of throat swab, Cerebrospinal fluid, Urine and blood during acute and convalescent stages of the disease. 

2.      IgG and IgM antibody detection can be done after recovery to confirm Nipah virus infection.

3.      Immunohistochemistry  on tissues collected during autopsy also confirms the disease

4.      Viral RNA can be isolated from the saliva of infected persons.

TREATMENT

1.      Currently there is no effective treatment for Nipah virus infection. The primary treatment for human cases is intensive supportive care

2.      All suspected cases of Nipah virus infection should be isolated and given intensive supportive care.

3.      Ribavirin- an antiviral drug, has been shown effective in in vitro tests, but has not yet been proven effective in humans.

4.      Passive immunization using a human monoclonal antibody that targets the Nipah G glycoprotein has been evaluated in the ferret model as post-exposure prophylaxis.

5.      The anti-malarial drug chloroquine was shown to block the critical functions needed for maturation of Nipah virus, although no clinical benefit has yet been observed.

 PREVENTION

Prevention of Nipah virus infection is important since there is no effective treatment for the disease. While there is no vaccine available for the infection, preventive measures can be a key to control the spread. With fruits bats being the primary cause of infection, the farm animals should be prevented from eating fruit contaminated by bats.

1.      The infection can be prevented by avoiding exposure to bats in endemic areas and sick pigs.

2.      Drinking of raw palm sap (palm toddy) contaminated by bat excrete, eating of fruits partially consumed by bats and using water from wells infested by bats should be avoided.

3.      Bats are known to drink toddy that is collected in open containers, and occasionally urinate in it, which makes it contaminated with the virus. Physical barriers can be put in place in order to prevent bats from accessing and contaminating palm sap.

4.      Medical officials who are looking after the patients with suspected or confirmed NiV should take basic precautions like washing hands, using a gown, cap mask and wearing gloves.

5.      For laboratory personnel, Nipah virus is classified internationally as a biosecurity level (BSL) 4 agent. BSL 2 facilities are sufficient if the virus can be first inactivated during specimen collection.

6.      In case of animals, wire screens can help prevent contact with bats when pigs are raised in open-sided pig sheds. Early recognition of infected pigs can help protect other animals and humans.

7.      Due to the highly contagious nature of the virus in swine populations, mass culling of seropositive animals may be necessary

8.      Surveillance and awareness are important for preventing future outbreaks. The association of this disease within reproductive cycle of bats is not well studied.

9.      Vaccine : 

•       A subunit vaccine using the Hendra G protein was found to produce cross-protective antibodies against henipavirus and nipavirus has been used in monkeys to protect against Hendra virus, although its potential for use in humans has not been studied.

-0-