Managment and Prevention of SARS Pandemic - Essay Example

SARS Pandemic Coronavirus are the causative agent for sever acute respiratory syndrome (SARS). These viruses received attention, about 70 years after their discovery, from the whole world in early 2003 when SARS was detected. The impact was huge in very short time interval; 8000 people became sick and 700 died across the globe. The rapid spread of the viruses is favoured by the established modes of transmission, which are droplet and contact. As no drug of choice is still available therefore, symptomatic treatment is provided to the patients, which consists of antibiotics, antiviral, corticosteroids, supplemental oxygen and immunoglobulons. Vaccine is in the preparatory phase. Once vaccine has been finally prepared would it possible to meet the demand of the world to prevent an event of pandemic through herd immunity. This is big question that is not an easy task to answer. Apart from availability, the cost of the vaccine would be an important factor. Developing countries would be at the worst hit because of affordability issues related to the cost of the vaccine. But pandemic will not be prevented if only the developed is vaccinated. It would have been possible to control the syndrome through directly observed treatment strategy (DOTS) if a drug of choice was available. Since no drug of choice is available and the vaccine does not seem to be of any substantial benefit so the only option left is the prevention. Prevention can be achieved through personal hygiene, sanitation of the environment especially with overcrowding like schools, aircrafts, etc. After a diagnosed case, the strategy used by the Canadian health authorities during 2003 outbreak seems an excellent guideline to follow when required. Coronaviruses are the causative agent for severe acute respiratory syndrome (SARS). These are positive strand RNA viruses of about 100nm and contain the largest genome among the RNA viruses. These viruses belong to the group of nidovirales, the other members of the group are: toroviruses and arteriviruses. Coronaviruses have helical nucleocapsides and envelops which are derived from intracellular membranes (Hunt 2005, Lwinson 2004). The coronaviruses discovered in the fourth decade of the last century but received attention in early 2003 when it was found that a new disease, SARS, which was started in the late 2002, was caused by these viruses (Hunt 2005, Lwinson 2004). SARS was responsible for the sickness of more than 8000 people while more than 700 people died of this syndrome around the world (SARS 2006). The habitat is animal body but the disease is spread when the animal-human barrier is crossed due to any factor (Peiris 2003). The virus is transmitted through droplet and contact (Hunt 2005, Lwinson 2004, Poutanen 2003, Yu 2004). Airborne mode of transmission is still not confirmed. There are some supporting data available but more information is needed to declare it as a mode of transmission. The contact of mucous membranes, of a potential candidate for SARS, with infected material seems important for the spread of the disease (Peiris 2003). The viruses are in different secretions of the body, like urine and faeces but the evidence for feco-oral route is missing (Olsen 2003). The SARS coronavirus (SARS-CoV) is actually less transmissible as, the ratio of one primary case to its secondary cases is only two to four but once it starts spreading and measures are not taken to control then the toll is very high (Olsen 2003). The incubation period estimated by various research teams have been in the range of two to ten days with mean duration of six days (Olsen 2003,Donnelly 2003). It has also been observed that it is very unlikely for the transmission to occur before the start of the symptoms and after 10 days of the resolution of fever (Olsen 2003). Based on the incubation period, the period of infectivity and the mode of transmission the viruses have infected humans in a variety of environments, like: workplaces of health care providers, lab workers working on samples of coronavirus related to SARS (Yu 2004), in taxis and even in aircrafts carrying SARS patients (Peiris 2003). The typical case of SARS present with fever, dry cough, dyspneoa and general influenza like symptoms (Donnelly 2003, Peiris 2003, SARS 2006). Management Pharmacological treatment There has been no specific treatment of SARS; the symptomatic treatment is started when a case is diagnosed and this includes: 1. Antibiotics 2. antiviral 3. corticosteroids 4. supplemental oxygen 5. Immunoglobulin support In China, a vaccine trial has been started but the results are still not supporting the cause (SARS 2006). Prevention Because of the non-availability of the treatment of choice as well as a specific vaccine the only available option to control the spread of SARS remains the prevention. These preventive measures are for different levels; individual level, family and community level, workplace level especially health care providers and the laboratory staff, and at the national level. Each level has got some measures, which are specific to that level (Epidemic alert 2004). At the national level: widespread community level information campaigns and seminars repeated messages on the mass media health education for the maintenance of personal hygiene, especially hygiene of hands implementation of maintenance of quarantine High risk groups: (Lim 2004) Laboratory workers Fever surveillance of laboratory workers Surveillance of pneumonia in special settings, like: nursing homes Surveillance of patients discharged with diagnosis of atypical pneumonia during and following SARS outbreak Laboratory based surveillance of SARS-CoV Surveillance for unexplained deaths following an acute respiratory illness Community and individual level Maintenance of hygiene, especially hands Maintenance of good health with balanced diet and exercise Avoidance of crowded locations WHO RAPF According to WHO, the world is passing through the interepidemic phase. There are two major areas to be focused for the spread of SARS: origin of SARS-CoV from the animal source; it becomes very difficult to eradicate the virus from this reservoir and presence of SARS-CoV in the laboratory for the diagnostic and other experimental/research purposes. These are the potential areas from where the re-infection could start which may lead to pandemic situation. Therefore, WHO has prepared guidelines for the surveillance of the diseases (Epidemic alert 2004). To strengthen the capabilities of different countries, WHO has developed a risk assessment and preparedness framework (WHO RAPF), the purpose of this framework is to (Epidemic alert 2004): Outline different scenarios which occur at sequential phases of a SARS outbreak Assign a level of risk as an outbreak occurs or escalates at each phase Suggest activities that areas with local transmission of SARS, SARS free areas and WHO should undertake Recommend surveillance activities should be established or strengthened as part of national preparedness planning There are phases of this framework ranging from phase 0 to phase 5; when there is no evidence of SARS-CoV transmission to humans and global interruption of SARS-CoV transmission respectively. This framework consists of different phases of evolution of SARS outbreak and provides generalized but comprehensive guidelines for different countries around the world to recognize and then control the spread of the SARS-CoV in local settings (Epidemic alert 2004). Pandemic state For any disease to spread across the region or around the world, called the pandemic state, it must fulfil the criteria established by WHO (Pandemic 2006). Pandemic status needs following conditions should be met: The emergence of a disease new to the population The agent infects human, causing serious illness The agent spreads easily and sustainably among humans Apart from these conditions one promoting factor is the mode of transmission of an infectious agent. Droplet mode of transmission is proved for SARS-CoV transmission but the evidence for the spread through airborne mode is still not confirmed. Transmission through droplet mode contains, usually, a dilute source of infectious agent, which may infect the close subjects (face-to-face) but the airborne mode, generally, infects those who are at a large distance because the infectious agent is carried away and it is in a quite sufficient quantity to pass on the required dose for the development of the diseases (Roy 2004). As compared to SARS, airborne transmission of tuberculosis has been demonstrated (Roy 2004). As far as SARS is concerned it successfully fulfils the criteria for pandemic occurrence. In current life style, there are some other factors, which also favour the spread of an infectious disease to a very large geographic area; the mode of travel and the reduction in physical distances between two points play an important role in this spread. There has been reports of spread of SARS on the aircrafts which are although well-ventilated cabins but at the same time they are overcrowded and increase the probability if the spread is through droplet and even greater chances when the spread is through airborne route, the evidence is still lacking (Roy 2004). Modern transportation and communication systems not only pose problems themselves in this regard, rather they create or promote situation which further move in the direction of spread of illness. These communications systems have converted longer distances into shorter ones and which can be covered in matter of hours. As is the case when a Chinese who was ill travelled to Hong Kong and spread the SARS-CoV to about 12 more persons. These infected individuals returned to their home countries harbouring the infectious agent and spread it in their countries. So in a matter of days the illness spread across more than 5 countries (Weinstein 2004). Non-availability of drugs Pharmacological agents are also important for the control of spread of any infection. If there is no drug of choice available against any infectious agent then confinement of the infectious agent becomes a very difficult task. This is the case with SARS as there is no specific drug available which can target the SARS-CoV. This is not the situation with tuberculosis. There is a good combination of drugs of choice for the treatment of tuberculosis but resistant strains of mycobacterium tuberculosis have been developed against these drugs mostly because of the non-compliance on the part of the patient. As this is called the disease of poverty, people are not cured because of not being able to complete the course while they are unable to get these drugs. Theses are the same people who do not have a good nutrition status. Therefore, WHO declared tuberculosis as global emergency in 1993 (Grange 2002). To control the problem of non-compliance, DOTS, was introduced which stands for directly observed treatment strategy. Through this strategy, the cure rate has increased and the burden of disease getting down. DOTS has played a central role in stopping and then bringing down the patient toll of those infected by mycobacterium tuberculosis (Amdekar 2005, Weis 1994). There has been no success in preparing any drug of choice for SARS-CoV. So the only option left for the control is to take preventive measures. SARS Vaccine One of the preventive strategies is vaccination against SARS-CoV. The vaccine against SARS-CoV is in the preparatory phases (Johnston 2004). Once it has been produced then there would be an issue of supply. It would be pharmaceutical companies on one hand working for making profits and of course they will get the profit from the developed countries who can pay and on the other end would be the needy community. For this vaccine the most eligible community would be the poor citizens of the developing countries, because: They are not fully equipped to take the preventive measures necessary if an epidemic starts in their area They are the least informed group They are the neglected group They are the un-accessible group They are with the environment, which facilitates further spread, overcrowded shelters, poor hygienic conditions, and prevailing malnutrition As there is no recommended treatment of choice in SARS the DOTS cannot be applied to control the deadly syndrome. Vaccine is still not available and if it becomes available it would not solve the problem due to supply issue. To prevent a population from communicable diseases vaccination of a sample of the target population is carried out to prevent the disease occurrence and then spread. To create the herd immunity in a population, the reliable level that can confer protection on the whole population is 90% vaccination of that population (Herd 2006). To prevent pandemic it will be needed to carry out vaccination of 90% of the population of the whole world. How will the issue of supply be tackled if all the other contributing factors are controlled Recommendations for measures to be taken to prevent outbreak (Roy 2004) Air sanitation in the aircrafts Screening of the passengers coming from the endemic areas Observation of quarantine if necessary Establishment of well-ventilated schools with air sanitation Establishment of well-ventilated army and police barracks and prisons Maintenance of good hygiene, especially hands Active surveillance by the clinicians Recommendations for measures to be taken when outbreak has occurred (Svoboda 2004) There are lessons can be learnt from the Canadian experience of dealing with SARS outbreak in Toronto. Community Awareness: Mass media played an important role. A regular update running system was established to keep the masses informed about the latest situation Tracking of potential cases: Toronto Public Health made arrangements to investigate and track all potential cases of SARS reported by clinicians Isolation and treatment: All cases of SARS were isolated and arrangements were made for their treatment in the hospital as inpatient cases Evaluation of institutions and infection control measures: the localities and areas where the SARS transmission occurred were evaluated for the SARS outbreak and then appropriate measures were taken to control the infection; everything was done in a collaborative manner between hospital staff and the public health teams Ban on nonessential staff members: Policy was made by the provincial ministry of health through which all hospitals were instructed to ban on the entry to hospital all those staff members who were not regular or not performing essential jobs; it was also banned that there would be no movements of the visitors except on compassionate grounds. Screening of all patients: all patients entering to the hospital, all staff members and visitors were screened for any symptoms of SARS or any risk factors which may lead to SARS. Protective dress: Health care workers were strictly instructed to wear gowns, protect eyes, and use gloves Potential SARS cases: all those cases diagnosed as potential ones were treated as cases of SARS until SARS was excluded. These all cases were classified according to Health Canada case classification Suspect cases: Re-classification was done as probable case for all suspect cases based on further diagnosis through radiography or autopsy Exclusion of SARS: If there was an alternative diagnosis for suspect case done then SARS was excluded Identification of close contacts: All the close contacts of the patients were identified through interviews, reviews of patients and visitor logs and employee schedules by Toronto Public Health staff in institutions and areas where the SARS was transmitted Referral of contacts: Proper arrangements were made for all those contacts that were identified as having SARS-like symptoms for referral for medical assessment Quarantine: All the contacts that were found asymptomatic were instructed to observe quarantine for a period of ten days after the last exposure, at their residences. During that time they were monitored for the appearance of the symptoms Work quarantine: to maintain infectious control measures for the prevention of the spread of illness and at the same time to meet the needs of the availability of sufficient staff members for the look after of the patients, work quarantine was arranged Following these measures, Canadian health authorities were successful in limiting and then controlling the outbreak in a very short period of time of about 4 months. The key message is the active surveillance on the side of the clinician in diagnosing a SARS case, suspect or probable and then taking immediate steps for the further management of that case. SARS fulfils all the conditions to lead a pandemic condition. There is no drug of choice available for the treatment of SARS; only supportive treatment is applied. Vaccine is in the experimental phase of preparation. If vaccine is introduced even then it would not be sufficient to localize the spread to a sub region. Non-availability of drug of choice disqualifies SARS for being a candidate for DOTS. Preventive measures remain the only available options before the establishment of an outbreak as well as during the outbreak. Personal hygiene is an important preventive factor. While the active surveillance by the clinician plays a pivotal role in detecting diseases and risk factors at an early stage. LIST OF REFERENCES Amdekar, Y. 2005,'Tuberculosis-the persistent threat to human health', Indian Journal of Pediatrics, vol. 72, no. 4, pp. 333-8 Donnelly, C., Ghani, A., Leung, G. Hedley, A., Fraser, C., Riley, S., Abu-Raddad, L., Ho, L., Thach, T., Chau, P., Chan, K., Lam, T., Tse, L., Tsang, T., Liu, S., Kong, J., Lau, E., Fergusom, N. & Anderson, R. 2003, 'Epidemiological determinants of spread of casual agent of severe acute respiratory syndrome in Hong Kong', The Lancet, [Online] Available at: http://image.thelancet.com/extras/03art4453web.pdf Epidemic alert and response, 2004, 'WHO guidelines for the global surveillance of Sever acute respiratory syndrome (SARS), [Online] Available at: www.who.int/entity/csr/resources/publications/WHO_CDS_CSR_ARO_2004_1/en/index.html - 19k Grange, J. & Zumla, A. 2002, 'The global emergency of tuberculosis: what is the cause' The Journal of the Royal Society for the Promotion of Health, vol. 122, no.2, pp.78-81 Herd immunity, 2006, 'Wikipedia, the free encyclopedia', [Online] Available at: http://en.wikipedia.org/wiki/Herd_immunity Hunt, R. 2005, 'Corona viruses, colds and SARS', Microbiology and immunology On-line, University of South Carolina, [Online] Available at: http://pathmicro.med.sc.edu/virol/coronaviruses.htm Johnston, R. 2004,'A candidate vaccine for severe acute respiratoy syndrome', New England Journal of Medicine, vol. 351, no. 8, pp.827-8 Lim, P., Kurup, A., Gopalakrishna, G., Chan, K., Wong, C., Ching, L., Se-Theo, S., Oon, L., Bai, X., Stanton, L., Ruan, Y., Miller, L., Vega, V., James, L., Ooi, P., Kai, C., Olsen, S., Ang, B. & Leo, Y. 2004, 'Laboratory-acquired severe acute respiratory syndrome', New England Journal of Medicine, vol. 350, no.17, pp.1740-5 Lwinson, W. 2004, Medical microbiology and immunology: examination and board review, McGraw Hill, California, pp.268-9 Olsen, S., Chang, H., Cheung, T., Tang, A., Fisk, T., Ooi, S., Kuo, H., Chen, K., Lando, J., Hsu, K., Chen, T. & Dowell, S. 2003, 'Transmission of the severe acute respiratory syndrome on aircraft,' New England Journal of Medicine, vol. 349, no. 25, pp.2416-22 Pandemic, 2006, 'Wikipedia, the free encyclopedia', [Online] Available at: http://en.wikipedia.org/wiki/Pandemics Peiris, J., Yuen, K., Osterhaus, A. & Stohr, K. 2003, 'The severe acute respiratory syndrome', New England Journal of Medicine, vol. 349, no. 17, pp.2431-41. Poutanen, S., Low, D., Henry, B., Finkelstein, S., Rose, D., Green, K., Tellier, R., Draker, R., Adachi, D., Ayers, M., Chan, A., Skowronski, D., Salit, I., Simor, A., Slutsky, A., Doyle, P., Krajden, M., Petrice, M., Brunham, R. & McGeer, A. 2003,'Identification of severe acute respiratory syndrome in Canada', New England Journal of Medicine, vol. 348, no.20, pp.1995-2005. Roy, C. & Milton, D. 2004, 'Airborne transmission of communicable infection-the elusive pathway', New England Journal of Medicine, vol. 350, no.17, pp.1710-12. SARS, Severe acute respiratory syndrome, 2006, 'Wikipedia, the free encyclopedia', [Online] Available at: http://en.wikipedia.org/wiki/SARS Svoboda, T., Henry, B., Shulman, L., Kennedy, E., Rea, E., Wallington, T., Yaffe, B., Gournis, E., Vicencio, S. & Glazie, R. 2004, 'Public health measures to control the spread of the severe acute respiratory syndrome during the outbreak in toronto', New England Journal of Medicine, vol. 350, no. 23, pp.2352-61. Weinstein, R. 2004,'Planning for epidemics-the lessons of SARS', New England Journal of Medicine, vol. 350, no.23, pp.2332-34. Weis, S, Slocum, P., Blais, F., King, B., Nunn, M., Matney, G., Gomez, E. & Foresman, B. 1994, 'The effect of directly observed therapy on the rates of drug resistance and relapse in tuberculosis,' New England Journal of Medicine, vol. 330, no. 17, pp.1179-84. Yu, I., Li, Y., Wong, T., Tam, W., Chan, A., Lee, J., Leung, D. & Ho, T. 2004,'Evidence of airborne transmission of the severe acute respiratory syndrome virus', New England Journal of Medicine, vol. 350, no.17, pp.1731-9. Read More