Background and history

Nipah virus is a henipavirus from the family paramyxoviridae. It is a recent disease that first became evident in September 1998 in Malaysia. In March 1999 a previously unknown virus was isolated from an adult male who having had contact with pigs died. The virus was identified as a previously unknown paramyxovirus and the disease was called Nipah disease from the village in Malaysia where it was first identified.

The virus causes illness and death in both humans and pigs.

Human health

Symptoms may be mild or severe and include:

• Fever, headaches, encephalitis.
• Drowsiness, confusion leading to coma.
• Respiratory failure.
• High mortality, up to 40 percent reported.
• A few people have shown no symptoms.
• The incubation period is from 7 to 21 days.

In 1999 there were over 300 cases and 100 deaths.

Clinical signs

• Morbidity is usually high but mortality is low.
• Rapid laboured breathing.
• Very harsh explosive cough.
• In sows disease may be more pronounced with severe breathing difficulties.
• Convulsions, death.
• Pneumonia.
• Mucopurulent discharges from the nose.
• At post mortem the predominant signs are consolidation of the lungs.

Diagnosis

This is by serological tests, virus isolation and identification. In infected farms sows show high levels of antibodies and in infected areas antibodies have been widespread in dogs but not in rats.

Causes

• Movement of pigs.
• Direct pig to pig contact either by mouth, by the respiratory route or aerosol from urinary excretions.

Prevention

The control programme adopted has been in two phases.

• In 1999 there was a mass culling of pigs in infected areas and severe restrictions on movement of pigs.
• This has been successful in preventing disease spreading to Singapore where many pigs from Malaysia were slaughtered.
• The second phase is the identification of carrier herds and their depopulation.

Treatment

There is currently no treatment for Nipah virus.