Disease Outbreak Reported
21 March 2003
Major step forward towards development of diagnostic test
A laboratory in a new network set up on Monday 17
March has today succeeded in growing, in cell culture, an infectious
agent that might be the cause of Severe Acute Respiratory Syndrome
This major step towards the development of a
diagnostic test has occurred despite the failure, up to now, to
pinpoint the exact identity of the causative agent.
Researchers at the laboratory took serum samples from
the blood of recovering SARS patients and a matching number of
healthy volunteers in what is known as a “blinded” test.
Serum from patients infected by a virus usually
contains neutralizing antibodies that stop the growth of the virus –
whatever its identity – when added to a cell culture in which the
virus has been successfully grown.
When the researchers added serum from SARS patients to
the cell culture, virus growth was halted. Serum from uninfected
healthy controls had no effect on the virus.
“This is not just some light at the end of the
tunnel,” said WHO virologist Dr Klaus Stöhr, who is coordinating the
collaborative laboratory efforts. “This is a real ray of
WHO cautions, however, that the number of patients in
the test was small and more work needs to be done. The scientific
community is excited by the news, which could be regarded as the
first important step towards the development of a diagnostic
The infectious agent resembles the morphology of a
Paramyxovirus. Scientists cannot, however, be certain about the
identity of the virus, which may indeed be a new Paramyxovirus or
another virus with a similar morphology.
The laboratory is one of 11 leading labs participating
in an international multicentre research project. The project was
set up by WHO on Monday to expedite identification of the causative
agent – considered by several research groups to be a member of the
Paramyxoviridae family of viruses – and rapidly develop a diagnostic
WHO team of experts travelling to China
A WHO team of five infectious disease experts will be
travelling over the weekend to China to support investigations there
of an outbreak of atypical pneumonia that began in Guangdong
Province in mid-November.
The multinational team was assembled in response to a
request from the Chinese Ministry of Health for epidemiological and
laboratory support to aid ongoing investigation of the outbreak. The
team will also assist in laboratory work that might lead to
identification of the causative agent.
The team includes experts in virology, laboratory
techniques, epidemiological investigation, and the control of
unusual infectious diseases. Team members, of American, Australian,
British, and German nationality, have been drawn from institutes
participating in the WHO Global Outbreak Alert and Response
The outbreak in southern China is linked
geographically and by timing to the current outbreak of Severe Acute
Respiratory Syndrome (SARS), which first surfaced in Asia in
mid-February and caused its first known death on 13 March. Cases of
this new disease have now been detected in 13 countries on three
continents. Hong Kong Special Administrative Region of China, which
as of today accounts for 203 of the 350 suspected or probable cases
reported worldwide, remains the most severely affected area.
Apart from searching for the causative agent, the WHO
team is expected to help Chinese scientists determine whether the
Guangdong outbreak included cases that fit the current definition of
Conclusive identification of the causative agent,
which is thought to be a virus of the Paramyxoviridae family, would
greatly aid the investigation by Chinese scientists and the WHO
team, which is expected to begin on Monday.
Research on the identity of the SARS pathogen is
progressing rapidly within a network of 11 leading laboratories set
up by WHO earlier this week. WHO remains optimistic that a
definitive announcement of the cause of SARS can be made soon.
History of the Guangdong outbreak
WHO was first officially informed of the outbreak on
11 February, when the Chinese Ministry of Health reported that 305
cases of acute respiratory syndrome of unknown cause had occurred in
six municipalities in Guangdong Province in southern China. Five
deaths were reported. Transmission of the disease was largely
confined to health care workers (105 doctors, nurses, and other
medical workers) and household contacts of patients.
On 14 February, WHO was informed by the Chinese
Ministry of Health that the outbreak was clinically consistent with
atypical pneumonia. Reported symptoms included fever, dizziness,
muscle soreness, and bouts of coughing. Patients had acute symptoms,
included high fever, dry cough, muscle pain, and weakness, and
required hospitalization. The Chinese authorities also provided
information that cases had been detected in the province as far back
as 16 November 2002.
In mid-February, some Chinese experts concluded that
the outbreak was caused by chlamydial organisms. Others speculated
that a virus might be the cause.
It is hoped that the WHO team can help authorities
quickly resolve these and other outstanding questions about the
Update on cases and affected countries As of 21 March,
350 suspected and probable cases, including 10 deaths, have been
reported from 13 countries. These figures represent an additional 44
cases and two new countries compared with the previous day. The
number of deaths remains unchanged.
Countries reported their first suspected cases are
Italy and the Republic of Ireland, each reporting one case. New
cases were reported in Hong Kong (30), Singapore (5), Taiwan, China
(2), Thailand (3), and the United States of America (2).
New guidelines for health authorities WHO has today
posted on its web site two documents to assist national authorities
in the investigation and management of cases. The first gives a more
complete, though still preliminary, clinical picture of SARS, pooled
from findings provided by clinicians treating SARS patients in seven
countries. It is anticipated that the clinical
description will help health authorities recognize cases with
The second document provides advice, including
recommended laboratory tests and radiological findings, that can
safe discharge and follow-up of convalescent cases. The policy
advice aims to ensure that the release of recovered patients carries
no risks for family members and other close contacts. Until more is
known about the etiological agent, and the potential for continued
carriage, WHO is recommending a cautious approach.