Eradicating Smallpox - Essay Example

 Smallpox is an acute infectious disease caused by variola virus which is a member of the orthopoxcirus family. In 1966, there were approximately 10 million to 15 million cases of smallpox in more than 50 countries, resulting in fatality of 1.5 million to 2 million people. The following paragraphs discussed its development, impact on individuals and the country. Variola virus existed in several forms, the more commonly found variola major and variola minor and the rarer forms, the haemorrhagic and malignant forms. The incubation period of small pox is from 7-17 days. During this period, there are no symptoms shown in the infected person and do not shed virus. After the incubation period, the disease is followed by the sudden onset of influenza-like symptoms including fever, malaise, headache, prostration, severe back pain and abdominal pain and vomiting, although the last two symptoms seldom occurs. These symptoms are followed by the falling of temperature and appearance of the rash on face, hands and forearms and body trunk. At this stage, lesions also develop in the mucosal membranes of nose and mouth and ulcerate very soon after their formation, releasing large amounts of virus into mouth and throat. The major forms showed lesions in more severe or milder forms, while in haemorrhagic forms, The rash is accompanied by haemorrhage into the mucous membranes and the skin. The malignant form is characterized by the failture of the lesions to develop into the pustular stage and remains soft and flat. Both the rare forms are fatal. The complications of smallpox includes deep pitted scars, blindness and limb deformity. About 65-80% survivors are marked with deep pitted scars, most prominently on the face. Another complication is blindness and in 18th century Europe, a third of all reported cases of blindness were due to small pox. In Vietnam, a survey conducted in 1898 showed 90% of all blindness was ascribed to smallpox. Limb deformity is another complications although it only occurs about 2-5% of cases. The fatality rate of smallpox is about 30% but there was no effective treatment. Recent research has suggested that antiviral drug such as cidofovir might be useful as a therapeutic agent (Bray & Roy, 2004). Caring of smallpox patients and reduced productivity also created economic burden to the society. In 1976, the cost on treating a patient with smallpox was $2.85 and the annual total cost of patient care was about 12 million in India. Based on this report, the cost of caring for patients with smallpox in developing countries was estimated to be more than $20 million in 1967. The lost of economic productivity was estimated to be $700 million each year due to the reduced economic performances in India (Ramaiah, 1976a, 1976b). Define eradication, extinction, elimination and control According to World Health Organization, eradication is the permanent reduction to zero of the worldwide incidence of infection caused by a specific agent as a result of deliberate effects. Intervention measures such as vaccination, are no longer needed. Smallpox is classified as an eradicated infectious disease. Extinction is defined in which the specific infectious agent no longer exists in nature or in the laboratory. Elimination can be further categorized into ‘elimination of infections’ and ‘elimination of disease’. Elimination of disease is the reduction to zero of the incidence of a specific disease in a defined geographical area as a result of deliberate efforts. Continued intervention measures are required. Neonatal tetanus is the example. ‘Elimination of infections’ is the reduction to zero of the incidence of infection caused by a specific agent in a defined geographical area as a result of deliberate effects. Continued measures to prevent re-establishment of transmission are required. Examples include measles and poliomyelitis. Control is defined as the reduction of disease incidence, prevalence, morbidity or mortality to a locally acceptable level as a result of deliberate efforts (Dowdle, 1998) Describe characteristics of smallpox that made it an appropriate candidate for eradication An infectious disease can only be eradicated if it meets the following conditions. Firstly, there is no known animal reservoir for the virus, and the risk of re-emergence from its natural reservoir can be minimized. The incubation period of smallpox is relatively long (7-17 days) in which there is no virus shedding. In addition, the rash developed on patient’s face makes it easier for medical professionals to identify and isolate people infected with smallpox. The above two reasons allow the disruption of disease transmission. Lastly, the survivors have lifelong immunity and the vaccination also provides ten years of immunity in minimum. This helps to stop the transmission by eliminating the natural host of smallpox. Should measles eradication program be initiated? Why and why not? Measles eradication program should not be initiated. Unlike smallpox, the transmission rate of measles is high and it is difficult to distinguish between endemic measles and imported cases. In addition, measles vaccine can only be effective if it is vaccinated when the baby is nine month or older. In Africa, this hinders the vaccination program since the clinics are usually far away from the children’s home and the mothers are unlikely to bring the children to the clinics. A small minority of population also requires a second dose in order to generate enough immunity against measles. Another problem is that measles vaccination is administered with a syringe and needle, which can only be used once, and may create additional burden to national programs (Arita, Wickett, & Nakane, 2004). The present strategy for eliminating measles is to lower the mortality rates and increase the coverage of vaccination in population. If polio is eradicated, should we destroy all poliovirus samples? Why or why not? Poliovirus samples should not be destroyed after polio is eradicated. The major concerns of possessing poliovirus samples after eradication are its potential use in biological terrorism and accidental release of poliovirus samples from laboratories. Polio is under eradication program at present. At present, polio samples are distributed worldwide (Dove, 1997), including places where nuclear terrorism is concerned, e.g. Lichtenstein and Libya. Therefore, destruction of the polio samples may not be possible. In addition, the synthesis of polio virus genome is possible due to its small genome size (Dove, 1997). The strain used in vaccination is called Oral Poliovirus Vaccine, which is an attenuated virus strains. There are also wild polio viruses. In recent decade, there are reports on sporadic re-emergence of polio ("Wild poliovirus weekly update," 2010) and a possible incidence of attenuated vaccine strains becoming virulent (Clarke, 2001). Therefore, research on polio is still necessary. In addition, recent research has also utilized polio virus as vectors in vaccine development (Crotty & Andino, 2004). Therefore, the polio virus samples should not be destroyed. In 1965, why didn’t the World Health Organization immediately undertake a full scale eradication program after endorsement by the World Health Assembly? In 1964, Smallpox Eradication Unit was set up to provide focused leadership for international efforts. However, there is a shortage of staff since there were only five full-time employees assigned to field programs before 1966. In addition, the invention of bifurcated needle in 1965 allowed reduced time for training in administering vaccine and total cost of vaccination. Bifurcated needle can be repeated used in vaccination program after being sterilized by heating with fire. In addition, the time needed for training volunteers to use bifurcated needles is approximately fifteen minutes and this enhances the efficiency of vaccination program in rural areas. Lastly, before 1965, there was not enough funding. In 1966, the World Health Assembly agreed to back the Intensified Smallpox Eradication Programme and allocated a budget of $2.4 million. All these allowed a full scale eradication program. References Arita, I., Wickett, J., & Nakane, M. (2004). Eradication of infectious diseases : its concept, then and now. Jpn. J. Infect. Dis., 57, 1-6. Bray, M., & Roy, C. J. (2004). Antiviral prophylaxis of smallpox. J. Antimicrob. Chemother., 54(1), 1-5. Clarke, T. (2001). Polio's last stand. [10.1038/35053235]. Nature, 409(6818), 278-280. Crotty, S., & Andino, R. (2004). Poliovirus vaccine strains as mucosal vaccine vectors and their potential use to develop an AIDS vaccine. Advanced Drug Delivery Reviews, 56(6), 835-852. Dove, A. (1997). When polio is gone, should we still vaccinate? , from http://microbiology.columbia.edu/pico/Chapters/News897.html Dowdle, W. R. (1998). The prinicples of disease elimination and eradication. Bulletin of the World Health Organization, 76(suppl 2), 22-25. Ramaiah, T. (1976a). Cost-benefit analysis of the intensified campaign against smallpox in India. Natl Inst Health Adm Educ Bull, 9, 169-203. Ramaiah, T. (1976b). Cost-effectiveness analysis of the intensified campaign against smallpox in India. Natl Inst Health Adm Educ Bull, 9(205-219). Wild poliovirus weekly update. (2010). 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