Description of the situation
25 June
WHO has today received reports of new probable cases of SARS in China and Japan.
China
The Chinese Ministry of Health has today reported a new probable case of SARS involving a 77-year-old woman who fell ill in Guangdong Province. The case had previously been classified as a suspect case and, according to WHO recommendations, was placed in isolation on 3 June.
This is the first new case reported in Guangdong since 17 May. The last new case reported anywhere in mainland China was on 11 June.
WHO is stressing that this is a reclassification of a suspect case as a probable case and, as such, should not be taken as an indication that local transmission has occurred. WHO is awaiting further details about the case and its relationship to documented chains of transmission that may point to the source of infection and the timing of exposure.
The most likely explanation is that the case, with its onset in early June, will be linked to a chain of transmission that was subsequently broken.
Meticulous records kept by Hong Kong authorities have revealed that the woman was hospitalized in Hong Kong and treated for other illnesses from 20 to 21 May. As her room was on the same ward as a SARS patient, she was placed under health surveillance until 1 June. No SARS symptoms developed during this period, which represents the maximum incubation period.
However, a possible link with the Hong Kong hospital cannot be entirely ruled out at this time. As became apparent during last week’s global conference on SARS, the disease does not always follow a clinically predictable course in elderly patients, particularly when they have been treated for co-morbidity with other diseases.
Guangdong, which saw the first cases of SARS in mid-November of last year, was removed from the list of areas with recent local transmission on 13 June. This retrospective reporting of a case newly classified as a “probable” case does not constitute a reason for any change in the status of Guangdong.
Japan
The Japanese Ministry of Health has today reported a probable case of SARS involving a 33-year-old man who arrived in Tokyo, for sightseeing, on 21 June and developed symptoms two days later. He was immediately hospitalized and managed according to WHO recommendations.
Initial diagnostic tests have ruled out other common causes of severe respiratory disease. Further testing is under way and epidemiological investigations have been initiated. As the patient is a resident of Taiwan, health officials there are contributing to the investigation.
Comment on new cases
When an outbreak wanes while vigilance is still high, a few additional cases are almost always detected. Their prompt reporting provides further assurance that surveillance systems are alert. However, WHO anticipates that many reported cases during this phase of the outbreak will turn out, on further investigation, to be “background noise” – that is, cases of community-acquired pneumonia caused by agents other than the SARS virus.
In areas that have experienced large outbreaks and therefore accumulated considerable skill in the clinical and laboratory diagnosis of cases, reports of newly detected probable cases are less likely to be discarded upon further investigation.