Nipah Virus Outbreak

Nipah Virus Outbreak- Cybermed Berita MMA


The new virus is not very contagious and if proper precautions are taken, it could be easily overcome. My only concern is ........at what cost?

The above were the comments I ended with in the March 99 issue of Berita MMA. The cost in mortality stands at present 101 dead as of 20 May 1999 (MOH site).(Down) The number of pigs culled, the cost of these various operations, loss of income and loss of jobs among pig farm workers, loss of revenue to the government in term of income earned from exports of pigs and tourism, other industries e.g. hotels, food stalls, etc,etc,etc, have yet to be finalised.

Culling operations have continued and is still continuing although no new reported cases in humans have been reported for some time. A brief look at the various areas where culling operations have taken place and are ongoing after Bukit Pelandok and Sikamat are (Links discontinued kept for historical reasons)

I am also concerned that the army will no longer be involved in culling operations. To organise such an exercise without them would place great strain on the districts involved. (Links discontinued kept for historical reasons)

The virus seems to have spread north and south from where it was originally thought to have started in Ipoh, Perak. In addition to this, the antibodies to the ?virus have been discovered in various animals. (Links discontinued kept for historical reasons)

Other animals have been implicated.. "Through testing at AAHL we have confirmed that humans, pigs, dogs, cats, horses, goats and bats have been infected by the Nipah virus. This information is critical in assisting the Malaysian veterinary services to successfully contain the virus and prevent further deaths" from a CSIRO press release.

The origin of the virus seems to have come from fruit bats according to Dr.Ksiazek. (Links discontinued kept for historical reasons)

"Although researchers were struggling to trace the Nipah virus' origins, Dr Ksiazek believed fruit bats related to the Pteropus species that carried the Hendra virus were harbouring Nipah."

An article in NewScientist has the following comments,

"BATS HAVE EMERGED as the most likely source of the deadly encephalitis which has swept through Malaysia, killing around 100 people. Antibodies to the virus responsible, which is called Nipah and is thought to have spread to people from pigs, have been found in two species of fruit bats. Hume Field of the Queensland Department of Primary Industry's Animal Research Institute in Brisbane is testing more than 300 blood samples taken from bats throughout Malaysia (This Week, 24 April, p 12). In some populations, up to 25 per cent of them seem to have been exposed to the virus. So far, however, the virus itself has not been isolated from bats, a crucial step necessary to confirm that the animals are the reservoir. But virologists at the US Centers for Disease Control and Prevention in Atlanta are now searching for it in bat tissue samples."

There were some questions raised on the test being used to confirm an animal being positive for nipah virus and thus the need for culling all the pigs in a farm. Majority of these was from ProMed site.

In the last article above, Charles H. Calisher ProMED-mail Viral Diseases Moderator mentioned the following,

"The basic problem remains definitions for "a case" and "an infection with". Antibody to a virus in a serum sample from an ill person or pig (or horse or anything else) is confirmatory of nothing.......A confirmed "positive", in terms of a human or a pig, depends upon either virus isolation or a change in antibody titers between paired acute- and convalescent-phase serum samples.  No doubt finding IgM antibody in a single serum sample from a sick human (or pig) provides excellent presumptive data, but it does not provide confirmatory evidence of recent infection. We have heard nothing regarding persistence of Nipah virus in pigs.  If there is evidence that persistent infections occur, we would like to know that -- as would everyone else.  If there is no evidence for such a persistent state, then why are pigs that are "positive" (assuming this means they have been shown to have antibody in a single serum sample) being killed?  Seems to me these immune animals would be the ones to retain."

In the article dated 19 May 1999, : D Stevenson asked the following,

"Is anyone in Malaysia considering that Nipah virus may have been around for many years, just as Lassa Fever [occurred] in West Africa for many years before it was separated from other conditions and identified with its present name ? Maybe these antibodies reflect past infections which were asymptomatic or attributed to other causes. Are there stored sera from the past, from people or from other species, which could be tested? Positive sera from the past might suggest different reactions to present circumstances."

Below is a recent statement, which appeared in the STAR, as how the pigs were deemed positive, - Shedding light on Nipah virus test (Links discontinued kept for historical reasons)

"A pig farm is only certified as being contaminated by the Nipah virus after at least three out of 15 pig blood samples from it are tested positive, said Johor Environment and Consumer Affairs Committee chairman Dr Chua Soi Lek."

It still does not answer the questions posed earlier. I have a few questions of my own,

If the test used was sensitive and specific for the detection of recent infection (rising titre) than the culling operations must go on and I fully support it but if it is not, we may be culling unnecessarily not only the pigs now, but later the dogs, cats, bats, goats, .....

These questions posed in Promed, newsgroups, articles, will probably continue until someone gives a clear answer.

Google
 
Web www.vadscorner.com


I have provided many useful links to Paramyxo group of viruses including Nipah virus and I will be updating this site as we hear more about this new Malaysian Paramyxovirus.


With that I let your "mouse" or your "keyboard" do the "talking".

Till next month, "Happy Surfing".

Cyberdoc (vadivale@geocities.com)

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The links to URL mentioned above are valid at the time of writing (23 May 1999).

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Last Updated 9th May 2005.