Coronavirus is the causative agent for the severe coronavirus is the severe acute respiratory syndrome (SARS) causative agent; These viruses gained attention from the entire world in early 2003 when SARS was discovered, about 70 years after their discovery. The impact was immense in a short time interval; 8000 people became sick, and 700 died across the globe. The rapid spread of the viruses is favored by the established modes of transmission, which are droplets And then touch.
Since no medication of choice is still available, symptomatic care, consisting of antibiotics, antivirals, corticosteroids, supplementary oxygen, and immunoglobulins, is given to patients. The vaccine is in the preparatory phase.
Once the vaccine has been finally prepared, would it possible to meet the demand of the world to prevent an event of the pandemic through herd immunity. This is a big question to answer, which is not an easy task. Apart from availability, a crucial factor would be the cost of the vaccine. Developing countries will be the hardest hit due to affordability concerns related to the vaccine’s benefit. But if only the formed ones are vaccinated, the pandemic won’t be prevented. But if only the formed ones are treated, the epidemic won’t be stopped. Where a medication of choice was available, it would have been possible to manage the syndrome through directly observed treatment strategy (DOTS). Since there is no drug of choice, and the vaccine does not appear to be of any substantial benefit, the only option left is prevention.
Prevention can be achieved through personal hygiene, environmental sanitation, in particular with overcrowding such as schools, aircraft, etc.
The technique used by health authorities in Canada during the 2003 outbreak, following a diagnosed case, seems to be an excellent guideline to follow when needed.
The causative agent for acute severe respiratory syndrome ( SARS) is coronaviruses. These are positive-strand RNA viruses that are approximately 100 nm long and contain the largest genome among RNA viruses. Such viruses belong to the group of nidovirals, with toroviruses and arteriviruses being the other class members. Coronaviruses have an envelope and helical nucleocapsids that Intracellular membrane derivatives (Hunt 2005, Lwinson 2004).
In the fourth decade of the last century, the coronaviruses discovered but were noticed in early 2003 when it was found that these viruses caused a new disease, SARS, which began in late 2002 (Hunt 2005, Lwinson 2004). SARS was responsible for the illness of more than 8000 people, while more than 700 people around the world died of this syndrome (SARS 2006). The habitat is an animal body, but the disease is spread when the animal-human barrier is crossed due to any factor (Peiris 2003).
Transmitting the virus can droplets and touch (Hunt 2005; Lwinson 2004; Poutanen 2003, Yu 2004). The airborne transmission mode is yet to be confirmed.
There are some supporting data available, but to announce it as a mode of transmission, more information is required.
Contact with infected material from mucous membranes, a potential candidate for SARS, seems essential for the spread of the disease (Peiris 2003). The viruses exist in various secretions of the body, such as urine and feces, but the evidence for the fecal-oral route is missing (Olsen 2003). The SARS coronavirus (SARS-CoV) is less transmissible as the ratio of one primary case to its secondary cases is only two to four. Still, once spreading starts and no control measures are taken, then the toll is very high (Olsen 2003). The period of incubation estimated by different research teams was in the range of two to ten days with a mean duration of six days (Olsen 2003, Donnelly 2003). It’s also noted that this is doubtful for the transmission to occur before the start of the symptoms and after ten Fever Solving Days (Olsen 2003). The cycle of infection and the mode of transmission of the viruses, depending on the incubation duration, have infected humans in several settings, such as health care providers’ workplaces, laboratories 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 presents with fever, dry cough, dyspnea, and general influenza-like symptoms (Donnelly 2003, Peiris 2003, SARS 2006).
There has been no specific treatment of SARS; the symptomatic treatment is started when a case is diagnosed, and this includes:
- Supplemental oxygen
- Immunoglobulin support
In China, a vaccine trial has been started, but the results are still not supporting the cause (SARS 2006).
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 support of quarantine
High-Risk Groups: (Lim 2004)
- Laboratory workers
- Fever surveillance of laboratory workers
- Surveillance of pneumonia in unique settings, like nursing homes
- Surveillance of patients discharged with a diagnosis of atypical pneumonia during and following the 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 a balanced diet and exercise
- Avoidance of crowded locations
The world is going through the interepidemic phase, according to WHO. There are two significant areas to be focused on the spread of SARS: the origin of SARS-CoV from the animal source; it becomes tough to eradicate the virus from this reservoir and the presence of SARS-CoV in the laboratory for the diagnostic and other experimental/research purposes. These are the potential areas where the re-infection could start, which may lead to a condition that is pandemic—consequently, the WHO has prepared guidelines for disease surveillance (Epidemic Alert 2004).
This project aims to strengthen the capabilities of various countries which have established a risk assessment and preparedness system (WHO RAPF) (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 which should undertake
- Recommend surveillance activities should be established or strengthened as part of national preparedness planning
There are phases of this framework ranging from stage 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 the SARS outbreak. It provides generalized but comprehensive guidelines for various countries around the world to recognize and then control the spread of the SARS-CoV in local settings (Epidemic alert 2004).
For any disease to spread across the region or around the world, called the pandemic state, it must fulfill the criteria established by WHO (Pandemic 2006). Pandemic status needs the following conditions should be met:
- A disease that’s new to the population
- The agent infects human, causing severe illness
- The agent spreads efficiently and sustainably among humans
Apart from these conditions, one promoting factor is the mode of transmission of an infectious agent. The droplet mode of communication 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 the infectious agent, which may infect the close subjects (face-to-face). Still, the airborne way, generally, affects those who are at a considerable distance because the infectious agent is carried away. 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 fulfills the criteria for pandemic occurrence. In the current lifestyle, there are some other factors, which also favor the spread of an infectious disease to a vast geographic area; the mode of travel and the reduction in physical distances between two points play an essential role in this spread. There have been reports of the range of SARS on the aircraft, which are although well-ventilated cabins. Still, at the same time, they are overcrowded and increase the probability of the spread is through a droplet and even higher chances when the range is through an airborne route, the evidence is still lacking (Roy 2004).
Modern transportation and communication systems not only pose problems in this regard. Instead, they create or promote a situation that further moves in the direction of the spread of illness. These communications systems had converted longer distances into shorter ones and can be covered in a matter of hours, as is the case when a Chinese who was ill traveled to Hong Kong and spread the SARS-CoV to about 12 more persons. These infected individuals returned to their home countries, harboring the infectious agent, and spread it in their countries. So in a matter of days, the illness spread across more than five countries (Weinstein 2004).
Non-Availability of Drugs
Pharmacological agents are also crucial for the control of the spread of any infection. If there is no drug of choice available against any infectious agent, then confinement of the contagious agent becomes a challenging task.
This is the case with SARS as there is no specific drug available that can target the SARS-CoV. This is not the situation with tuberculosis. There is a right combination of drugs of choice for the treatment of disease. Still, 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. These are the same people who do not have a functional nutrition status. Therefore, the WHO declared tuberculosis a 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 is 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.
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 the one hand, working for making profits, and of course, they will get the benefit from the developed countries who can pay and, on the other end would be the needy community. For this vaccine, the most desirable 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. The vaccine is still not available, and if it becomes available, it will not solve the problem due to the supply issue. To prevent a population from infectious 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 decent level that can confer protection on the whole community is 90% vaccination of that population (Herd 2006). To prevent a pandemic, it will be needed to carry out treatment of 90% of the people of the whole world. How will supply problem be addressed if all other contributing factors are monitored?
Recommendations for outbreak prevention measures to be taken (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 the 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 an outbreak has occurred (Svoboda 2004)
Some lessons can be learned from the Canadian experience of dealing with the SARS outbreak in Toronto.
- Community Awareness: Mass media played an important role. A regular update operating system was set up to keep the masses informed of the latest situation
- Tracking of potential cases: Toronto Public Health made arrangements to investigate and track all possible cases of SARS reported by clinicians
- Isolation and treatment: All instances 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 steps were taken to control the infection; everything was done collaboratively 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 the hospital all those staff members who were not regular or not performing essential jobs; it was also forbidden that there would be no movements of the visitors except on compassionate grounds.
- Screening of all patients: all patients entering 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 a probable cause 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 connections that were found asymptomatic were instructed to observe quarantine for 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 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 short period of about four months. The key message is the active surveillance on the side of the clinician in diagnosing a SARS case, suspect or probable, and then take immediate steps for the further management of that case.
SARS fulfills 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. The vaccine is in the experimental phase of preparation. If a 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 essential preventive factor, while active surveillance by the clinician plays a pivotal role in detecting diseases and risk factors at an early stage.
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