Nipah virus infection (NiV) is a viral infection caused by the Nipah virus. Symptoms from infection vary from none to fever, cough, headache, shortness of breath, and confusion. This may worsen into a coma over a day or two. Complications can include inflammation of the brain and seizures following recovery.
The Nipah virus is a type of RNA virus in the genus Henipavirus. It can both spread between people and from other animals to people. Spread typically requires direct content with an infected source.[The virus normally circulates among specific types of fruit bats. Diagnosis is based on symptoms and confirmed by laboratory testing.

Management involves supportive care. As of 2018 there is no vaccine or specific treatment.Prevention is by avoiding exposure to bats and sick pigs and not drinking raw date palm sap. As of 2013 a total of 582 human cases of Nipah virus are estimated and 54 percent of those who were infected died.] In 2018, an outbreak of the disease resulted in at least 10 deaths in the Indian state of Kerala.

The disease was first identified in 1998 in Malaysia and Singapore with the virus being identified in 1999.It is named after a village in Malaysia, Sungai Nipah.Pigs may also be infected and millions were killed in 1999 to stop the spread of disease.

Key facts

•     Nipah virus is an RNA virus that is part of the Paramyxovidae family that was first identified as a zoonotic pathogen after an outbreak involving severe respiratory illness in pigs and encephalitic disease in humans in Malaysia and Singapore in 1998 and 1999.

•     Nipah virus can cause a range of mild to severe disease in domestic animals such as pigs.

•     Nipah virus infection in humans causes a range of clinical presentations, from asymptomatic infection (subclinical) to acute respiratory infection and fatal encephalitis.

•     Nipah virus can be transmitted to humans from animals (bats, pigs), and can also be transmitted directly from human-to-human.

•     Fruit bats of the Pteropodidae family are the natural host of Nipah virus.

•     There is no treatment or vaccine available for either people or animals. The primary treatment for humans is supportive care.

•     Nipah virus is on the WHO list of Blueprint priority diseases

Signs and symptoms

Human infections range from asymptomatic infection, acute respiratory infection (mild, severe), and fatal encephalitis. Infected people initially develop influenza-like symptoms of fever, headaches, myalgia (muscle pain), 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, including acute respiratory distress. Encephalitis and seizures occur in severe cases, progressing to coma within 24 to 48 hours.

The incubation period (interval from infection to the onset of symptoms) is believed to range between from 4-14 days. However an incubation period as long as 45 days has been reported.

Most people who survive acute encephalitis make a full recovery, but long term neurologic conditions have been reported in survivors.  Approximately 20% of patients are left with residual neurological consequences such as seizure disorder and personality changes. A small number of people who recover subsequently relapse or develop delayed onset encephalitis.

The case fatality rate is estimated at 40% to 75%; however, this rate can vary by outbreak depending on local capabilities for epidemiological surveillance and clinical management.

Diagnosis

Initial signs and symptoms of NiV infection are non-specific and the diagnosis is often not suspected at the time of presentation.  This can hinder accurate diagnosis and creates challenges in outbreak detection and institution of effective and timely infection control measures and outbreak response activities.

In addition, clinical sample quality, quantity, type, timing of collection and the time necessary to transfer samples from patients to the laboratory can affect the accuracy of laboratory results.

NiV infection can be diagnosed together with clinical history during the acute and convalescent phase of the disease. Main tests including real time polymerase chain reaction (RT-PCR) from bodily fluids as well as antibody detection via ELISA.  Different tests include:

    enzyme-linked immunosorbent assay (ELISA)
    polymerase chain reaction (PCR) assay
    ·virus isolation by cell culture.





Source: http://www.who.int/news-room/fact-sheets/detail/nipah-virus