The Directorate General of Health Services (DGHS) in a press release yesterday confirmed the Nipah outbreak.

It said samples of blood and tissue of sick patients had been sent to the Centre for Disease Control and Prevention (CDC) Atlanta, US. The CDC on January 20 conveyed the test report that shows one patient is Nipah positive.

The deadly virus is transmitted from animal to human and requires close contact with contaminated tissue or body fluids from infected animals.

The DGHS, in the wake of the CDC report, has taken immediate measures to further investigate the mode of transmission and epidemiology of the virus. It is also collecting more samples to analyse suspected illness among other neighbouring inhabitants in the affected villages in Habla union in Basail.

"We're very alarmed by the result and now have no doubts that the 'unknown' viral attack in Tangail is a Nipah outbreak," said Prof Mahmudur Rahman, director of Institute of Epidemiology, Disease Control and Research (IEDCR).

"The high mortality rate is more alarming in Bangladesh if we consider the Nipah outbreaks in Goalanda in Faridpur and Meherpur a few of years back," he added.

The rate in Malaysia where the virus was discovered or suspected to have originated was 39 percent whereas in Faridpur it was 73 percent.

According to World Health Organisation (Who), Nipah virus is a newly recognised virus discovered in 1999. It causes disease in animals and then in humans through contact with infectious animals.

Certain species of fruit bats are currently believed to have been the hosts of the virus.

It is currently believed certain species of fruit bats are natural hosts of the virus, but it cannot be known how it is transmitted from them to animals.

Antibodies to the virus have been detected in pigs and other domestic and wild animals, according to the Who. However, the role of species other than pigs in transmitting Nipah virus has not yet been determined.

It is unlikely that the virus is easily transmitted to man, although previous outbreak reports suggest Nipah virus is transmitted from animals to humans more readily.

Despite frequent contact between fruit bats and humans, there is no serological evidence of human infection from bat carriers. Pigs were the apparent source of infection among most human cases in the Malaysian outbreak, but other sources such as infected dogs and cats cannot be ruled out, said a WHO release.

The WHO release also said the incubation period of the virus is between four and 18 days. In many cases the infection is mild or not apparent (sub-clinical). In symptomatic cases, the onset is usually with 'influenza-like' symptoms, with high fever and muscle pains. The disease may progress to inflammation of the brain (encephalitis) with drowsiness, disorientation, convulsions and coma. Fifty percent of clinically apparent cases die.

No drug therapies have yet been proven to be effective in treating Nipah infection. Treatment relies on providing intensive supportive care. There are a few pieces of evidence that early treatment with the antiviral drug can reduce both the duration of feverish illness and the severity of the disease. However, the efficacy of this treatment in curing the disease or improving survival is still uncertain.

From September 1998-April 1999, there was a large outbreak of encephalitis in Malaysia. During investigation, Nipah, a previously unrecognised virus, was identified as the causal agent. As many as 265 people were infected and 105 of them died.