Bella Dave considers the impact of severe acute respiratory syndrome

In late 2002, reports of a new severe respiratory disease began to emerge from Guangdong in southern China. Now defined as severe acute respiratory disease (SARS), explosive outbreaks in Hong Kong, Singapore, Vietnam, Canada, and China brought it international attention in early 2003. As the first serious new infectious disease of this century, it was unusual in its high morbidity and mortality, and took full advantage of the opportunities provided by a world of international travel and hospital environments. By July 2003, 8437 cases of SARS had been reported worldwide, leading to 813 deaths.¹

SARS causes fever then rapidly progressive respiratory compromise, chills, muscle aches, headache, loss of appetite, and diarrhoea--similar to influenza and other causes of atypical pneumonia. The cause of SARS is a new coronavirus, almost identical to viruses isolated from palm civet cats, a delicacy in southern China, and other wild animals from food markets in the city of Shenzhen. Whether these animals are the origin of the coronavirus, is still uncertain. Chinese food handlers, including caterers and chefs, were heavily represented among the first patients with SARS, consistent with SARS being a zoonosis. Having crossed species from animals to people, SARS then spread from person to person.² About three quarters of diseases emerging in the past decade were zoonotic.

Multi-phase spread

Initially appearing as small clusters of atypical pneumonia in Guangdong province, although out of the ordinary was not considered exceptional. But the referral of a patient to a tertiary hospital in Guangzhou with presumed viral pneumonia led to the global alert. For two days he was in the 2nd Affiliated Hospital of Sun Yet-San Medical University before being transferred to another hospital. During this time, 28 medical personnel fell ill with SARS, as well as the ambulance driver who transferred him. The early and high attack rate amongst hospital staff was a constant feature in outbreaks elsewhere. SARS spread outside of Guangdong province when a nephrologist who had been treating patients with this atypical pneumonia traveled to Hong Kong. He stayed at the Metropole Hotel in Kowloon on 21 February 2003.³

More than seven other people staying on the same floor of the hotel contracted SARS from the index case and they sparked the outbreaks in Canada, Vietnam, Singapore, and elsewhere in Hong Kong. A local person was admitted to the Prince of Wales Hospital on 4 March, and it was from this patient that the disease spread through the hospital, ultimately infecting over 100 medical personnel. This was the first phase of the SARS outbreak in Hong Kong.³⁴

The second phase of the SARS epidemic in Hong Kong began when it started to spread into the community. The largest community outbreak occurred in the Amoy Gardens, a housing estate in Kowloon. The index case was a 33 year old man who was being treated at the Prince of Wales Hospital for chronic renal disease. He developed symptoms on the 14 March 2003, and on that day and the 19 March he visited his brother who lived in a flat in block E of the estate. He had diarrhoea and used the brother's toilet. By the 15 April 2003, 321 cases of SARS had been diagnosed among the residents of Amoy Gardens; two fifths of them lived in block E. Environmental factors played a large part in this outbreak, due to aerosolised sewage particles arising from the sewage waste disposal systems.

An economic and health burden

SARS showed how a newly emerging infectious disease can wreak global havoc. It brought the healthcare systems of entire areas to a standstill by striking down doctors and nurses--people vital for the control of disease. Surgery and vital treatments for patients had to be postponed. A large proportion of patients with SARS needed intensive care, which added considerable strain to healthcare systems. The importance of infection control in the hospital environment has been downplayed for many years yet was crucial in managing SARS. Hospitals, schools, and borders were closed, and travel was severely reduced, contributing to the profound economic impact of SARS. The impact of the media responses to the outbreak ranged from the sensible and useful to the silly and dangerous, and shows the importance of handling the media during outbreaks so that the general public are informed accurately.

Another lesson learnt was the need for global cooperation in controlling infectious diseases, at the epidemiological, clinical, and scientific levels. SARS is a strong reminder that everyone has a personal health interest in what happens in other countries. Borders and oceans are not the barriers they once were, and SARS showed the impact of air travel in the speed of transmission of this pathogen. Farming practices, housing, and inadequate public health measures in developing countries around the world can adversely affect health anywhere.

Political will and commitment

The outbreak showed the effectiveness of a high level political commitment to contain an outbreak even when there are no sophisticated tools. Outbreaks in mainland China also showed the consequences of suppressing health information. In contrast, Vietnam was the first country to bring SARS under control by the diligent application of centuries old control techniques--isolation; infection control; contact tracing; and follow up, quarantine and travel restrictions, and also rapid requests for help from the outside world.¹ A strong and open public health system is needed to combat emerging diseases, and this can only be developed or maintained with political and financial will.

The World Health Organization played a vital role in containing SARS by issuing global alerts and emergency travel recommendations and quickly set up collaborative networks in laboratory diagnosis and research, clinical management, and epidemiological investigation. One month after issuing a global alert, the causative agent was isolated by laboratories working within the WHO global network. The early recognition of the cause made it possible to rapidly develop diagnostic assays, the details of which were made available on the internet. This shows how the scientific community around the world can come together effectively to identify new pathogens and the value of the internet. Such an effort limited the potentially explosive spread of the disease. SARS has mobilised resources for the worldwide public health infrastructure necessary to deal with rapidly spreading deadly infections. Will SARS return, and if so, cause significant human spread? Where did it come from? Are there drugs or vaccines that can be developed? The answers are unknown, but hopefully the lessons learnt from 2003 will reduce the impact of other outbreaks of SARS, avian and human influenza or other infections.

Guidelines: We intend publishing within 24 hours all responses that contribute substantially to the topic under discussion. To avoid points that have already been made please read other people's responses before posting your own. All responses will be eligible for publication in the paper studentBMJ, providing that current appointment and place of work are given. Name and email address are required to send a response and will be published with the response.

Please note: When writing a respnse to a response, please enter the original title of the article and the author of the response you are responding to.