[CathyRyan]

I am thinking we are trying to piece a puzzle without all the pieces. Time will tell and I guess all we can do is wait and see.

[Mother Abigail]

We are able to confirm that the patient whose NPA [nasophayngeal aspirate] was found to contain paramyxovirus is a health care worker with SARS who was exposed to the index patient in the medical ward associated with the outbreak at the Prince of Wales Hospital in Hong Kong. Degenerated primer sets for paramyxoviruses were used in a RT-PCR [real-time polymerase chain reaction] in the patient's NPA. Multiple bands from the PCR product were sequenced. A sequence was found to be compatible to paramyxoviruses.

Subsequent application of this RT-PCR in specimens collected from three other health care workers who were exposed in the same medical ward and presenting symptoms of SARS showed similar bands. Sequencing of these PCR products are in progress.

[Mother Abigail]

In addition to finding paramyxovirus-like particles in throat swabs and sputum specimens from the doctor from Singapore and his mother-in-law currently treated in the isolation unit in Frankfurt am Main, Germany, similar structures have now been identified in the plasma of the mother-in-law.

Although further testing to confirm the finding of what could potentially constitute a novel paramyxovirus (as the presence of known human-pathogenic paramyxoviruses was largely ruled out by using a multitude of other tests) is urgently needed and under way in several laboratories, the detection of such particles in the blood might indicate active viremia and thus underline a potentially causative role for the agent.

[Mother Abigail]

Research teams at two laboratories, in Germany and Hong Kong Special Administrative Region of China, have detected particles of a virus from the Paramyxoviridae family in samples taken from patients with severe acute respiratory syndrome (SARS).

This is the first major step forward in efforts to pinpoint the causative agent. Previous tests conducted in a number of top laboratories failed to detect the presence of any known bacteria or viruses, including the influenza viruses, recognized as causes of pneumonia or respiratory symptoms, or known to be widespread in the most affected geographical areas.

The failure of all previous efforts to detect the presence of bacteria and viruses known to cause respiratory disease strongly suggests that the causative agent may be a novel pathogen.

Firm conclusions about the identity of the causative agent are premature. All teams have stressed that these are preliminary results only. Further studies are needed before it can be concluded, with confidence, that the causative agent has been identified.

All research teams are participants in the international multicentre SARS research project, linking together 11 leading laboratories, that was set up on Monday 17 Mar 2003. Coordinated research is expected to expedite definitive identification of the causative agent.

The detection of paramyxovirus particles in samples from infected patients is the first lead to a possible cause of SARS and will be extremely important in focusing ongoing research. Definitive identification of the causative agent will help physicians move from the current "hit-or-miss" approach to treatment to a more precise selection of drugs with a greater prospect of cure.

Knowledge of the causative agent will also speed development of a diagnostic test and thus give physicians and national health authorities a powerful tool for the identification of cases. It will also reassure the many "worried well" now presenting at health facilities, and reduce the number of false alarms.

Update on countries and cases
As of Wednesday 19 Mar 2003, a cumulative total of 264 suspected or probable cases and 9 deaths have been reported from 10 countries (Canada, China, Germany Singapore, Slovenia, Spain, Thailand, the United Kingdom, the United States of America, and Viet Nam). Hong Kong SAR, Hanoi (Viet Nam), and Singapore continue to be the most affected areas. Full details are provided in tabular form.

Awareness of the disease is now very high throughout the world. Surveillance is proving to be sensitive, with suspected cases rapidly detected, reported to national authorities and WHO, and investigated according to the standard case definition.

The Paramyxoviridae family
Viruses in the Paramyxoviridae family include many common, well-known agents associated with respiratory infections, such as respiratory syncytial virus, and childhood illnesses, including the viruses that cause mumps and measles. Some of these viruses are widespread, particularly during the winter season. Screening of specimens could therefore be expected to detect particles of these common viruses. At this point, it cannot be ruled out entirely that tests for the SARS agent are detecting such "background" viruses rather than the true causative agent.

The Paramyxoviridae family also includes two recently recognized pathogens, Hendra virus and Nipah virus. These related viruses are unusual in the family in that they can infect and cause potentially fatal disease in a number of animal hosts, including humans. Most other viruses in the family tend to infect a single animal species only.

Nipah virus first began to cause deaths in humans in Peninsular Malaysia in 1998 in persons in close contact with pigs. The outbreak caused 265 cases of human encephalitis, including 105 deaths. Two separate outbreaks of Hendra virus, associated with severe respiratory disease in horses, caused two human deaths in Australia in 1994 and 1995. No human-to-human transmission was documented in either outbreak. No treatment was available for cases caused by either of these two viruses. Human-to-human transmission did not occur.

[Mother Abigail]

In addition, we have also included information from the Singapore Ministry of Health website mentioning that a paramyxovirus has been preliminarily identified from patient(s?) in Singapore. While specifics on the testing used in Singapore are not available in the MOH press release, this is now the third location to preliminarily identify paramyxovirus from specimens taken from SARS patients.

Once a viral agent has been identified and confirmed from multiple patients, in multiple geographic locations and specific tests for the virus have been developed, more of the suspected cases of SARS can be tested to see if they have evidence of recent infection with the identified virus. This "step-wise" process is important to confirm that the agent is in fact the agent responsible for SARS. - Mod.MPP]

[Evidence is accumulating that the etiologic agent of SARS is a paramyxovirus. The report from Germany suggests that known paramyxovirus pathogens of humans have been excluded. The report from Hong Kong is rather vague and difficult to evaluate in the absence of precise information on the nature of the PCR-primers employed or the identity of the product sequenced. The limited evidence available at present suggests that the putative agent of SARS is a novel paramyxovirus rather than a known paramyxovirus exhibiting atypical pathogenicity.
A variety of novel paramyxoviruses have been characterized in recent years, some of which have been listed in my comment to "PRO/EDR> Severe acute respiratory syndrome