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Tuesday 03 of October 2023 01:10:59 AM


RRX Pharma Virus - SARS
SARS research:

RRX is conducting a preliminary investigation of the SARS virus as part of a preliminary survey for possible consideration of automated analysis.

Corona virus technical details.

Note: Current Situation in Toronto, Canada (Updated July 02, 2003)

SARS Outbreak Infection Statistics - Canada

Wednesday, July 2, 2003

WHO has today removed Toronto, Canada, from its list of areas with recent local transmission of SARS. The last probable case was detected on 12 June and immediately isolated. When 20 days, or twice the incubation period, have passed without detection of a new case, the chain of human-to-human transmission is considered broken.

“This is a great achievement for public health in what we hope is the final phase of the global emergency,” said David Heymann, the WHO Executive Director for communicable diseases. “Toronto faced an especially challenging outbreak. As we have learned, SARS is a difficult disease that produces many surprises and setbacks.”

“We should all pay tribute to the health workers and others in Canada who had their lives disrupted and threatened by this disease. When the virus returned to start a second outbreak, health workers continued the fight and have now won it. We also need to remember the commitment of Canada’s scientists, who rapidly provided information about the virus and its epidemiology that has benefited public health around the world.”

Toronto was among the first areas affected after the virus moved out of southern China, in late February, and began to spread internationally. WHO advised travellers to avoid all but essential travel to Toronto on 23 April. The advice was lifted a week later. On 14 May, Toronto was removed from the list of areas with recent local transmission, only to return on 26 May after the virus surfaced in a second outbreak.

All of the earliest and most severe SARS outbreaks have been traced to contact with an infected medical doctor from Guangdong Province, China, who spent a single night (21 February) on the 9th floor of the Metropole Hotel in Hong Kong. At least 16 guests and visitors to the same floor became infected. One has been identified as the source case, at the Princes of Wales Hospital, for the Hong Kong outbreak. Others, who carried the virus with them when they returned home, seeded outbreaks in Toronto, Viet Nam, and Singapore.

The mechanisms by which the virus spread from one infected person to so many guests and visitors are still not fully understood. No hotel staff were infected.

Another mystery is why the SARS virus spreads more efficiently in sophisticated hospital settings – another factor that may have contributed to the severity of Toronto’s outbreak. Both epidemiological and anecdotal evidence suggests that certain procedures, such as difficult intubation and use of nebulizers, that are more common in sophisticated hospitals also increase the risk of infection.

When the outbreak began in Toronto and, simultaneously, at the other initial sites, no one was yet aware that a new disease, capable of rapid spread within hospitals, had surfaced in China. Hospital staff, struggling to save lives, were unaware of the need to protect themselves. As a result, the SARS virus spread rapidly within hospitals and then out into the wider community as other patients, hospital visitors, and close contacts of staff became infected.

After WHO issued the first global alert to SARS, on 12 March, all countries experiencing imported cases, with the notable exception of Taiwan, have been able to either prevent any further cases or keep the number of additional cases very small.

With today’s change in the status of Toronto, Taiwan now remains the last area in the world to have experienced recent local transmission of SARS.

Friday, June 13, 2003 the category of pattern of SARS transmission for the city of Toronto has been changed from “B” to “C”. This is because a probable case with laboratory confirmation of SARS coronavirus exported from Toronto had not been previously identified as a contact and put into voluntary home isolation. “Pattern B” transmission is defined as an area having more than one generation of local probable SARS cases, but only among persons who have been previously identified and followed-up as known contacts of probable SARS cases. “Pattern C” transmission is defined as an area having local probable cases occurring among persons who have not been previously identified as known contacts of probable SARS cases.

Thursday, June 12, 2003 global media reports of apparently one possible case of SARS has been verified as exported from Toronto to the US. Notably there are concerns that Canadian HCWs apparently failed to notify US authorities of the possibility.

The World Health Organization (WHO) has added Toronto, Canada (May 26, 2003) to the list of areas with recent local transmission of SARS. The change in status follows information, communicated by Health Canada, about new clusters of 26 suspect and 8 probable cases of SARS linked to 4 Toronto hospitals. Notably Health Canada has released a document revised on May 30, 2003 with new SARS case definition guidelines.

Apparently an urgent alert was sent on May 23, 2003 to all health and long-term care facilities and service providers in Toronto. Potential exposures may include staff, patients, visitors and related contacts. Notably the SARS virus contamination may also have spread from the Toronto area to hospitals in Ottawa (June 2, 2003). Procedures are apparently in place for exit screening the thermal emissions of all travellers leaving the Toronto area.

As a precautionary measure, apparently all cases are being treated as possibly representing SARS virus contamination until proven otherwise. Actions being taken include immediate isolation of all possible cases, heightened infection control, intensive contact tracing, and voluntary or enforced home quarantine of identified contacts. These measures have proved reasonably effective in quickly containing outbreaks. Apparently over 7000 possible cases were in quarantine effective May 30, 2003 as a preliminary countermeasure. Notably global media reports (BBC June 1 , 2003) indicate numerous quarantine cases in Toronto have been ignoring quarantine orders.

Although the results of laboratory and epidemiological investigations are pending, apparently sufficient information is available to determine that the index, or first, case in the present outbreak has transmitted infection to others in more than one generation of local transmission. Toronto is therefore classified as having “pattern B” transmission. This is defined as more than one generation of local probable SARS cases.

Significantly on June 11, 2003 the World Health Organization is deeply concerned by the resurgence of SARS cases in Toronto, reported to WHO on 22 May, and is following the situation closely. Toronto, which had been removed from the list of areas with recent local transmission on 14 May, was again added to the list on 26 May following evidence that more than one generation of new cases had occurred. Since the disease first resurged in Toronto, over 90 new probable cases have been reported.

Health authorities in Toronto are again on high alert, and are treating all hospital-associated clusters of patients with fever or respiratory symptoms as possible SARS cases until proven otherwise. Possible cases are immediately isolated. All contacts are being traced and, when warranted, placed in home quarantine. Infection control measures are being followed in all affected facilities. WHO welcomes these precautionary measures.

Canadian authorities have most recently reported a possible cluster of SARS patients in a hospital east of Toronto. Although no clear epidemiological link has been established that could explain this new cluster, officials have adopted a cautious approach. Over the last 3 days, 15 dialysis patients at the Lakeridge Health Centre in Whitby exhibited respiratory and febrile illnesses. After clinical review and laboratory investigations to detect other causative agents, around half of these patients have now been excluded from consideration as possible SARS cases. The remaining patients are being closely monitored.

These are other investigations are ongoing and many questions remain to be answered before firm conclusions can be reached.

WHO is also awaiting further information on cases in other countries that may have been exported from Toronto. WHO is not yet convinced that such cases have been conclusively documented.

One of the most dangerous stages in the evolution of any outbreak, and most especially one caused by a new and poorly understood disease, occurs when cases begin to decline and previous levels of high alert and precautionary measures likewise begin to level off. Much about the clinical behaviour of SARS and its mode of transmission requires further research. Until knowledge improves, precautionary measures such as those being followed in Toronto are the best approach from a public health perspective.


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