Emergencies preparedness, response

Update 64 - Situation in Toronto, detection of SARS-like virus in wild animals

23 May 2003

Situation in Toronto
Health authorities in Canada informed WHO yesterday of a cluster of five cases of respiratory illness associated with a single hospital in Toronto. As a precaution, the cluster is being managed as possibly representing cases of SARS until proven otherwise. Intensive laboratory and clinical investigations are under way. As of today, no links had been established between these five patients and recent probable cases of SARS, which are all well documented.

WHO was informed today by Canadian authorities that further information should be available early next week. Pending the results of this investigations, there is no change in the status of Toronto, which was removed last week from the WHO list of areas with recent local transmission.

Comments on the reported isolation of viruses related to the SARS coronavirus in wild animals in southern China
Research teams in Hong Kong and Shenzhen, China have today announced the results of a joint study of wild animals taken from a market, in southern China, selling wild animals for human consumption. The study detected several coronaviruses closely related genetically to the SARS coronavirus in two of the animal species tested (masked palm civet and racoon-dog). The study also found that one additional species (Chinese ferret badger) elicited antibodies against the SARS coronavirus. These and other wild animals are traditionally considered delicacies and are sold for human consumption in markets throughout southern China.

All six of the civets included in the study were found to harbour SARS coronavirus isolated in cell culture or detected by a PCR molecular technique. The animals also seroconverted and their sera inhibited the growth of SARS coronavirus isolated from humans. Vice versa, human serum from SARS patients inhibited the growth of SARS isolates from these animals.

Sequencing of viruses isolated from these animals demonstrated that, with the exception of a small additional sequence, the viruses are identical with the human SARS virus.

Information on the potential role of animals in the transmission of SARS is important to overall understanding of SARS. Much more research is needed before any firm conclusions can be reached. At present, no evidence exists to suggest that these wild animal species play a significant role in the epidemiology of SARS outbreaks. However, it cannot be ruled out that these animals might have been a source of human infection.

As a precautionary measure, persons who might come into contact with these species or their products, including body fluids and excretions, should be aware of the possible health risks, particularly during close contact such as handling and slaughtering and possibly food processing and consumption.

The study provides a first indication that the SARS virus exists outside a human host. However, many fundamental questions remain. Samples were taken from one market only. Studies need to determine how widespread the SARS virus might be in animals in Guangdong and elsewhere, and if these animals can excrete virus in an amount sufficient to infect humans. Furthermore, the possibility of animal-to-animal transmission has to be investigated. For example, the presence of virus could result from consumption of an infected prey.

Update on cases and countries
As of today, a cumulative total of 8117 probable cases with 689 deaths have been reported from 28 countries. This represents an increase of 77 new cases and 7 deaths when compared with yesterday. The new deaths occurred in China (3), Hong Kong (2), and Singapore (2).

Most of the new cases were reported in Taiwan, China. With 55 new cases reported today, Taiwan now has a cumulative total of 538 probable cases, making it the third most severe outbreak site to date.