Since SARS has now re-emerged in Vancouver (Promed, Canadian health officials, and WHO denials not withstanding), it is worthwhile reviewing the various version of SARS that have been documented from the beginning of the outbreak. Canada actually was first to described SARS CoV infections in patients with a wide range of symptoms. The Winnipeg Labs initially found SARS via PCR in 40% of probable cases (who also had pneumonia), 35% in suspect cases (who did NOT have pneumonia) and 20% in patients who did not meet the case definition. While the Toronto case mortality rate for probable SARS was in the 15-20% range (and higher for older patients), it was near zero for suspect cases as well as those who did not meet the case definition. WHO only reported probable cases, and those cases had pneumonia.
Thus, compilation of cases that include the milder cases without pneumonia, who have a lower case mortality rate, will lower the case fatality rate lower in proportion to the number of milder cases included. The Canadian report (in JAMA) on 144 cases had a low mortality rate because about 50% of the cases were suspect cases, which effectively cut the case mortality rate in half, since there were virtually no deaths among the milder cases.
With the new outbreak of SARS in Vancouver, there is much speculation about the "mysterious" illness or "flu-like illness", which of course is nonsense. The patients tested negative for the influenza virus, and incidence of flu in the summer are very low. A remarkably high percentage of the patients however were positive for SARS CoV (10/19) or antibodies (4 of 7) for SARS CoV. The PCR data is higher than that described above for probable SARS cases in the spring in Toronto.
Thus, there is no need to invent new diseases or viruses to explain the outbreak in Vancouver. Like the Vancouver outbreak in the spring, most of the cases do not have pneumonia and most will survive. If fact there had been no reported SARS deaths in Vancouver until now.
It seems it is time to face up to the reality of a re-emergence of SARS and acknowledge that the virus can cause a broad spectrum of diseases. It also seems likely that the spectrum of disease and symptoms can broaden even wider under different seasonal conditions. |
