The epidemic first broke out in October in pig farms in Perak and was reported to have killed 15 people before spreading to Negeri Sembilan two months later.
The outbreak was first brought to the attention of doctors subscribing to the Doctors Only BBS (DOBBS) on the 16 of November 1998. The outbreak was thought to be due to Japanese Encephalitis. The sequence of events as it unfolds were well documented in the various postings in DOBBS. (See article - DOBBS and the Viral Encephalitis Outbreak)
What went wrong? Why have there been so many deaths before we had some idea that another new virus (paramyxovirus) was involved? (See article - Factsheets about a new Paramyxovirus isolated during the viral encephalitis outbreak in Negeri Sembilan). I have searched the internet and came across many articles including newspaper articles with many conflicting statements which probably compounded and made more cloudy the outbreak situation. It is easy at this present time to say this or that should have been done but nevertheless an audit of some sort needs to be undertaken to see where we went wrong and how we can improve ourselves.
I like to look back at a question I posed to Prof.Lam Sai Kit during a cyberinterview in relation to the enterovirus outbreak in Taiwan.
There have been a lot of questions recently on the Internet as to the exact pathogen involved. Some say its EV71 and some say its a type of Adenovirus, and yet some feel it may be a combination of pathogens. Based on your observation and experience taking into consideration clinical, serology, virology, post-mortem, previous literature (historical), etc what in your opinion is the likely pathogen.
I think good science and hard facts must apply in such a situation. We must be clear in the case definition based on clinical histories. Once we have a consensus on the cause of death, then we can move on and look at the laboratory evidence and see whether this can support the clinical events.
Did this happen during this outbreak?
Did we ask questions when the deaths were increasing?
Did the Veterinarian see anything different among the pigs in terms of their behaviour to alert them? If there was a difference it might have pointed us on the correct path of management. How did the outbreak spread to Negeri Sembilan and Singapore? This cross-border spread has to be investigated to determine the source. What about the horses that died in Tambun, Perak? Any attempt made to find the cause of death?
Did the public health people involved suspect that this outbreak appears to be different from previous known outbreaks of JE? We have to now check on all previous cases of JE to determine/confirm if they are JE or this new virus. This will answer the questions, when, where and whom was infected first and hopefully point towards the source of infection. This will also serve as an audit on all specimens examined.
Did the laboratories involved (IMR) follow standard procedures in such a situation? Did we send samples to other laboratoires in Malaysia for an opinion or is it standard procedure to send samples overseas?
Most interestingly, do we have an national epidemic outbreak plan?
This article written by Prof.Lam Sai Kit was published in Berita MMA Vol.29 No.1, January 1999 issue about Japanese Encephalitis in Malaysia. Abstract from it reads as follows-
JE in Malaysia
The disease is endemic in Malaysia and the first report was published by Cruikshank in 1951, describing an outbreak among British prisoners during the Second World War. Paterson et al (1952) demonstrated neutralizing antibodies to JE virus in human and equine sera in Malaysia and Pond, McCrum and Simpson (1954) found that the virus also infected pigs, bovines, dogs, goats and sheep.
The number of cases from 1985-1993 totaled 273 but the actual number of cases could probably be more (Tan Lian Haw, 1995). Three outbreaks have been reported, 1974 in Pulau Langkawi (10 cases, 2 deaths); 1988 in Pulau Pinang (9 cases and 4 deaths); and 1992 in Serian, Sarawak (9 cases, 4 deaths). Thirty-one percent of cases between 1989-1993 were in children 0-4 years, 52% in the 7-14 year age group, 9% in the 15-24 year age group and 8% in adults >25 years. Cases have occurred principally in children below 14 years accounting for 83% of all cases. More males (62%) are affected than females (38%).
Did the current outbreak epidemiological figures seem different at least in the mortality, number and age group involved?
We are now told we have a mixed outbreak of Japanese encephalitis and a new yet to be named virus. With an initial diagnosis of Japanese encephalitis it probably resulted in a certain amount of complacency. But it is good we had people with open minds and who were willing to question the norms when their laboratory findings did not fully support this. Kudos, to University Malaya, especially to Prof.Lam Sai Kit and his team who within a short period of time when they started seeing specimens from Negeri Sembilan(1 March 1999) were not only able to identify that it may not be just JE but a new virus. It does us proud in an otherwise sad situation to know that we have great scientific minds among us Malaysians. Congratulations to Dr.Chua Kaw Bing on this achievement. This is not the first time that this illustrious team have done us proud. I remember the so called Coxsackie outbreak in which they were able to identify Enterovirus 71 as a likely pathogen. Several papers on Enterovirus 71 has since been published. This information helped the Taiwanese manage their outbreak which they have since attributed it to the same pathogen. (See Enterovirus Epidemic, Taiwan, 1998 and Chang Kung Children Hospital serological survey). This same team helped identify the mysterious disease that afflicted people in Klang as Chikungunya virus.
New Malaysian Paramyxovirus
Let us have a look at some postings and information available on the Internet.
The anecdotal information on the disease in pigs was posted on 23 March 1999 in Promed (PRO/AH> Hendra-like virus? - Malaysia (07) ).
I have the following anecdotal info on the disease in pigs in the Perak (Ipoh) outbreak from 2 sources: 1. This one is from Singapore vets. The information was given to them in Ipoh by Malaysian pig farmers regarding on-farm pigs. Pigs of all ages were observed to have marked dyspnea with open mouth breathing, epistaxis, marked coughing, "bluishness and malodour" to the carcass at death. 2. This description was given by a Malaysian physician in Ipoh whose parents died of the disease. The pigs first became irritable and started to bite other pigs. They then coughed severely until haemoptysis occurred. They then started fitting and died.
This information is vital as it helps define (if the above is correct) a possible case presentation of a typical infected pig. I hope we can now work on a possible ?test to identify infected pigs. The diagnosis of JE and the subsequent vaccination of all pigs (which was a good step) in itself probably helped propagate the disease further as the same needle was used from one pig to another. (CNN) (Link broken)
In man, the disease has not been described except in a DOBBS posting (17 March 1999) in which is mentioned the following summary of 30 cases.
27m 3f mean age 33.9 (13-52)yrs bkt pelanduk 73% Sg Nipah
nil - 20%
1 - 3.3%
2 - 36.7%
don't know - 6%
clinical: does not affect pyramidal system if recovers - very well rapid onset coma ? Brain stem involvement epidemiological: direct pig handlers rather than only staying in area adults affected, few children pigs dying
diagnostic tests used inhouse IgM Elisa panbio eia from austra haemagg inhib pcr with je primer virus isolation - vero, ps, c6/36 suckling mice only 51.7% confirmed to be je by 1 or more tests as above expect 100% seropos in pair samples but 50% seroneg pts with paired samples isolation of new virus from 5 csf in vero cells - caused paralysis in mice
The new virus:
syncytial cpe in 24hrs size & morph in em - 140-160nm unlike JE (smaller) isolation in vero kills mice in 2 days presence of Ab to ciinical isolates member of paramyxovirus rather than flavivirus (eg measles, hendra, australian bat lyssa + other zoonotic virus) awaiting confirmation from cdc possibility of use of ribavarin as for enveloped rna viruses .
What we know so far about this new virus is from Prof.Lams article, Factsheets about a new Paramyxovirus isolated during the viral encephalitis outbreak in Negeri Sembilan.
This new Malaysian Paramyxovirus was first tested in CDC, Fort Collins and found not to be related to any known arboviruses. In addition, reverse-transcriptase polymerase chain reaction using consensus primers directed against alphaviruses, flaviviruses and bunyaviruses were negative. At CDC, Fort Collins, electron microscopy on a grid of infected cells prepared in the University of Malaya showed foci of thickening plasma membrane with hairy-like projections suggestive of virus morphogenesis at the cell membrane. The virus appears as pleomorphic, envelope particles (spherical and elongated) of 200 to 300+ nanometer and helical nucleocapsids were noted within the envelope. Multinucleated cells were prominent and the nuclei appear normal. The virus particles are compatible with paramyxoviruses and cross-react with Hendra virus antibody by immunofluorescence. CDC Atlanta has developed a serological test for Hendra IgM and a number of serum samples from the current outbreak has been shown to be positive. (See full article in this issue along with the first image of this new paramyxovirus)
Finally, we must support MOH at times like this so as to ensure the present viral encephalitis outbreak is brought under control. I applaud the DG of MOH for releasing press statements(Down) to disseminate information to the public, doctors and media.
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?
I have provided many useful links on Japanese encephalitis and Paramyxo group of viruses including Hendra 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".
The links to URL mentioned above are valid at the time of writing (31 March 1999).
This page can be accessed at http://www.vadscorner.com/internet25.html or at http://www.vadscorner.com/mma_internet.html.
Last Updated 9th May 2005