An Outbreak Investigation of Severe Acute Respiratory Syndrome - Assignment Example

Outbreak investigation of SARS Q1. How the outbreak was established? The first patient to encounter the disease of SARS was a 33-year old man who resided in Shenzhen, Guangdong in China and used to visit his brother in Amoy Gardens in Hong Kong. He had a chronic renal disease for which he was taking treatment from the Prince of Wales Hospital. He got SARS symptoms on March 14, 2003 and till March 19, he continuously visited his brother. He also had a diarrhea at that time and used his brother’s toilet while visiting. Subsequently, his brother and sister-in-law developed the disease from him. This event is further elaborated by www.library.thinkquest.org, where according to the site; the first victim of SARS was a 48 year old Johnny Chen, who was first found mildly sick during his trip to Hong Kong and Shanghai. Though he returned to Hong Kong for treatment, but couldn’t tolerate the sickness and succumb to death. Later it was found that Chen caught SARS from a Chinese doctor who had been treating patients in Guangdong, where SARS broke out for the first time, and he was also staying at the same hotel as Chen in Hong Kong. The disease was mainly discovered to be transferred from animals to humans. This virus is called corona viruses which a person can catch from not only the wild animals but also the tamed animals like cats and dogs roaming around. But this was discovered later in 2004. In the initial stages, it was believed that the infection was established due to improper and unhealthy hygiene conditions and foul smell from the toilits. Q2. How the diagnosis was confirmed? The diagnosis is confirmed when a patient develops any of the respiratory pathogens which include influenza virus, Para influenza viruses, respiratory syncitial virus etc. In addition to this, there is seldom any laboratory test that gives a reliable result of SARS diagnosis in the first few days of illness. According to World Health Organization (WHO), caution must be taken in diagnosing non specific viral pneumonia without ascertaining risk factors for SARS with in the 10 days of illness. This means that it must be determined whether any family member or colleague or social contacts had any similar illness or have a relevant history to travel to such areas where SARS-CoV out broke. A typical clinical case of SARS has the symptoms of fever along with temperature up to 38 degrees centigrade or more, short breathing and cough or pneumonia in lungs without any identifiable cause. Q3. How the cases were defined and how many cases were reported? The cases of SARS were defined on the basis of frequent transmission patterns, demographics and clinical, which showed a few disparities in case-fatality proportion with pneumonia. ‘The WHO guidelines for the Global Surveillance of SARS 2004’ states the case definition as an individual who shows clinical and epidemiological evidence for SARS with preliminary laboratory proofs of the infection based on the following tests performed: a. A single positive antibody test for SARS CoV or b. A positive PCR result for SARS CoV on a single clinical specimen and assay. The case was defined as an illness that occurs in any person after the outbreak on February 1, 2003, with a history of high fever; one or more respiratory symptoms, and close contact with a person in whom SARS has been diagnosed and/or a history of travel within 10 days of symptoms to an area with reported SARS transmission. Till March 26, around 1323 cases of suspected and probable SARS that met the case definitions by World Health Organization were reported from 14 locations world wide. These reported SARS cases include 49 deaths (case-fatality proportion: 4%). The Chinese authorities have reported 792 suspected/probable cases, including 31 deaths, which occurred in Guangdong province during November 16, 2002--February 28, 2003 [CDC, 2003]. Q4. How the population at risk was defined? The population which was highly at risk from SARS were the Health Care Workers (HWC) who were most exposed to this infection. There is another term used to point towards those people who have to take care and live with SARS cases. These people are called CONTACTS and they have a greater risk of developing SARS because they get exposed to the infection by taking care of the patient, living with him or having direct contact with him. This results in the direct encounter with the respiratory secretions, body fluids or excretions of the SARS patients. Q5. How the cases were described in terms of time (of onset, diagnosis, etc.), place, time, and person (age/sex/ethnic group, etc.) The transmission of SARS-CoV which is claimed by the scientists to be an animal virus is a highlighted feature of SARS outbreak. In terms of persons, majority of the cases are adults. The infection is less common in children as is not as severe as in adults. The average time period is 5 days with a range of 2-10 days for these infected cases. Cases outside this range do not usually report the SARS virus and so are not required to be rigorously tested. Transmission occurs within a family, social groups or vicinities, but no transmission has been reported before the onset of symptoms. Q6. Was any hypothesis formulated to explain: the source, mode of transmission and duration of the outbreak? The hypothesis was formulated on the basis that if a case shows the sign of SARS within the 10 days of virus or respiratory disorder, it would consider being a SARS case. On the other hand, if case doesn’t show the symptoms of SARS during 2-10 days of viral and the illness exceed this time, the case will be discarded by the physician. Besides that, the case is considered confirmed if it shows clinical and epidemiological evidence for SARS where epidemiological evidence shows the linkage to a chain of human transmission. Q7. Was the hypothesis tested by any analytical study? Yes the above hypotheses were tested by an analytical study of testing and verifying algorithm for SARS in the inter-epidemic period as well as during the outbreak. The results showed that preliminary positive cases as well as those which are epidemiologically proven will be considered as confirmed SARS cases. Any unverifiable case will be considered as a probable case if it is linked to the confirmed case of SARS. Health authorities should not discard any case if its initial test result is negative and clinical and epidemiological evidence is supporting the diagnosis. Lastly the person under observation should be discarded if the illness doesn’t show negative signs or results of SARS after 28 days of onset of symptoms. Q8. What was the control plan and what was the control measures implemented? The control plan proposed by World Health Organization was named as ‘SARS Risk Assessment and Preparedness Framework’. The major purposes behind the introduction of this plan was to outline different scenarios in which SARS outbreak, the risks involved in this during each phase of the virus transmission, to suggest activities which can be undertaken by the SARS hit areas as well as SARS free areas at the same time and to recommend surveillance activities which can be performed by the countries to be established as a part of the National Preparedness Plan. The above plan was brought forward because since July 2003, SARS reappeared four times, three of these were due to breaches in laboratory biosafety, resulting in one or more cases of SARS in Taipei and Beijing. On the other hand, only one case was reported of secondary transmission outside of the laboratory. This situation was considered as a threat to human lives and so WHO ordered all the countries to keep a check on all its laboratories which are working with SARS-CoV culture and ensure that correct biosafety procedures are followed by them while working with such dangerous pathogens. The pan was implemented by dividing it into six phases ranging from 0-5. At phase zero, there was no evidence of SARS transmission worldwide. While in the first phase, there is a case of SARS but it doesn’t lead to secondary cases; on the other hand second phase has those cases which transmit the disease resulting in outbreak. Phase three shows an international spread of the infection, while phase four shows a slow down in the whole transmission process of SARS. Phase five gives an interrupted halt to the SARS transmission worldwide. Q9. How was the effectiveness of control measures evaluated? The Risk assessment and Preparedness plan in countries was effective in a way that the SARS was controlled in a span of one or two years through out the world. Now, there are fewer cases reported of this disease and the major role playing component here is the rapidly increased knowledge and awareness about the disease it self and also the potential risk of outbreaks in different countries. Though many researches are still done on SARS virus, but the case definitions which were clearly provided by the scientists reduced the number of SARS cases by half. With apparent definitions of ‘Confirmed case’ and ‘Probable case’, the doctors are able to detect the patients in a better way and diagnose them for this disease. Before the control measures, there was a restriction on the social gatherings and travel of SARS patients. Not only have that, on countries like Toronto, Hong Kong, Taiwan, China, where the SARS outbreak, ‘Centres for Disease Control and Prevention’ put travel alert. These alerts were then removed after the implementation of the control measures. Besides that, the SARS cases were reported mainly among HCW-Health Care Workers. ‘The majority of these infections have occurred in locations where infection-control precautions either had not been instituted or had been instituted but were not followed. Recommended infection-control precautions include the use of negative-pressure isolation rooms where available; N95 or higher level of respiratory protection; gloves, gowns, and eye protection; and careful hand hygiene.’ [CDC, May 16, 2003 / 52(19); 433-436]. This problem was also overcome to an extent with increasing awareness and risk management information. Many countries took preparedness measures which saved them from SARS. These measures includes the development of a comprehensive system of surveillance for global infectious diseases, the enhancement of disease reporting, the development of diagnostic tests, and the formulation and distribution of guidelines on diagnosis. Q10. How the information given to the public was handled? Outbreak of SARS spread a wave of concern among the general public, which not only included the residents but also the physicians and specialists. The rumours were spread everyday regarding the infection, making the situation worse. Besides these, there were a lot of important features and characteristics which need to be communicated to the people regarding SARS and its victims. Many researches were done and websites were launched to educate the public regarding the SARS and its victims. As the disease was highly transmitted, many people were reluctant to keep their infected family members with them so as to save themselves from it. This scenario gave way to many psychological problems and inferiority complexes on part of the patients. They secluded themselves from their families and started living in isolation. To handle this situation, many health nutritionists and experts stepped in and educated not only the general public regarding their cleanliness and health activities but also gathered the authorities looking after the sewerage and drainage systems. As the main reason behind the outbreak of SARS was the unhealthy sanitation and foul smell from the toilets which carried SARS germs with them, these authorities must know about the severity of the situations in case of unhealthy and poorly maintained sewerage systems. Reference: 1. ‘Cluster of Severe Acute Respiratory Syndrome Cases among Protected Health-Care Workers’ --- Toronto, Canada, April 2003 CDC, May 16, 2003 / 52(19); 433-436. Source: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5219a1.htm 2. World Health Organization-‘ Severe Acute Respiratory Syndrome (SARS)- Guidance on SARS; Source: http://www.who.int/csr/sars/guidelines/en/index.html 3. ‘WHO Guidelines for global surveillance for SARS’ WHO/CDS/CSR/ARO/2004.1, October 24. 4. WHO Scientific Research Advisory Committee on SARS- 20-21 October 2003 SRAC-CDS/CSR/GAR/2004.16 Read More