Epidemiology of Ebola - Essay Example

? Epidemiology of Ebola Epidemiology of Ebola Ebola is an emerging hemorrhagic fever that is fatal in humans and nonhumanprimates that appear sporadically in several African countries since it was recognized in 1976. The disease is caused by the Ebola virus, named after the Ebola River in Congo where it was first reported. The Ebola virus belongs to the family of RNA viruses called Filoviridae. There are four subtypes of the virus that cause Ebola in humans: Ebola-ivory coast, Ebola-Zaire, Ebola-Sudan, and Ebola-Bundibugyo. The fifth subtype called Ebola-Reston causes the disease in nonhuman primates (Holtz, 2008). The Ebola virus is similar to Marburg virus that caused a deadly outbreak of hemorrhagic fever in Germany and Yugoslavia in 1967. Both viruses cause death within a short time, and they are identical morphologically, but different serologically. The virus has an estimated fatality rate of between 50 and 80 percentage in Uganda and Zaire respectively. Secondary and tertiary infections have a lower fatality rate due to attenuation of virulence with the human-to-human passage (Khardori, 2006). A laboratory worker was admitted in Kikwit Hospital in Zaire with abdominal distension in April 1995. The patient had developed the complication after a protracted fever and died within six days. By July the same year, 315 cases had been recorded of which 244 patients died, which is equivalent to 77 percent. In September 2012, another outbreak was reported in the democratic republic of Congo (formerly known as Zaire). According to WHO, there were 69 cases that had been reported of which nine were confirmed in the laboratory. The number of cases reported doubled within a week and were localized within the same areas. Health care workers constitute almost a third of the reported cases due to contact with infected people. The disease causes dehydration and weakens the patients reducing their mobility. This localizes the disease outbreak and the spread can be contained by reducing the movement of people in and out of the infected zone (Hewlett and Hewlett, 2007). Ebola viruses appear as long filamentous forms, short U-shaped, 6-shaped, or in circular forms. The filamentous worms have a maximum length of 14,000 nm. Peak infectivity occurs when the worms are 970 nm and a uniform diameter of 80 nm (Dry and Leach, 2010). They are made of nucleocapsid, envelope containing material from the plasma membrane of the host, and a surface layer containing glycoprotein projections. The virus contains one molecule of non-infectious, linear, single strand RNA and seven polypeptides. The virus has a replication similar to other negative-stranded RNA viruses containing monopartie genome. Ebola strains have a cytopathic effect in tissue culture and intracytoplasmic vesiculation and mitochondrial swelling are accompanied by organelle breakdown and cytoplasmic condensation. The infectivity of the virus is stable at room temperature, but it is destroyed by exposure to temperature above 60 degrees (Stimola, 2011). The viruses are zoonotic and transmitted to humans from the life cycles of other animals. Bats are believed to be the reservoir of both Ebola and Marburg viruses. The first cases of Sudan virus were factory employees working in a room where bats roosted. The virus discovered in Ivory Coast in 1994 was first recorded in chimpanzees that were feeding in a fig tree together with fruit bats (Dworkin, 2011). The Reston virus reported from 1989-96 appeared in primates exported from Philippines from a fruit orchard with fruit bats. The Zaire virus has antibodies and Gnome RNA similar to that in 3 species of bats in Gabon. In 1996, fruits bats were infected with the virus in a lab and replicated the virus without developing the disease. Competition for fruits between fruit bats and non-human primates leads to transmission of the virus from one species to another. Domestic animals contract the virus when they come in touch with saliva, urine, feces, and birth fluids from infected primates (Barrett and Stanberry, 2008). Suspected modes of transmission to humans include: contact between bats and miners, geologists, and hunter; contact with secondary hosts such as pigs; and contact with infected human beings. Infections with the virus are acute, and there is no carrier state. Direct contact with infected blood and secretions from an infected person can spread the virus from one person to another (Colfer, 2008). The high number of health workers infected when there is an outbreak occurs due to contact with patients. Research has shown that 7 out of 12 family members are infected when there is a family member with the virus. This occurs due to contact with body fluids when caring for the sick person. Ebola virus can also be transmitted trough contact with objects contaminated with infectious secretions. Health workers attending to patients without protective clothing have a high probability of contracting the virus. Other patients in a hospital can contract the virus through contaminated needles and syringes (Nelson and Williams, 2007). The virus has an incubation period of 2 to 21 days. The onset of illness occurs abruptly and is characterized by fever, headache, muscle and joint aches, sore throat, diarrhea, vomiting and red eyes. Rashes, hiccups, and internal and external bleeding are reported in some patients (Halfmann, 2008). Infected people who develop a significant immune response are able to survive an infection of the virus. The virus does not have a standard treatment and patients are given supportive therapy. Physicians try to balance the body fluids of patients, control blood pressure and oxygen, and manage secondary infections that occur. The current climate change has increased the interaction between human beings and wildlife. Human beings have encroached on forests and other natural habitats of wildlife. Changing environmental conditions also force animals to migrate from their habitats to human residential areas (Cook, Zumla and Manson, 2009). Pigs and other domestic animals graze in the forest where they come into contact with excretions from primates and fruit bats. The bats feed by masticating pulp from fruits and spitting out seeds and juices. Animals coming into contact with these seeds and juices contract the virus, which is then transmitted to humans. The destruction of forests by changing climatic conditions attracts bats into backyards and pasture areas. Human beings and grazing animals come into contact with excretions form these animals leading to a transfer of the virus. Global warming may cause the virus that currently exists in the tropics to thrive in cold regions. The warm climate may also cause changes in the epidemiology of the virus making it dangerous. Unusual variations in rainy and dry seasons have made Ebola outbreaks more frequent, and the variations may cause the spread of the virus into other areas. Ebola surveillance aims at early detection of new infections in order to avoid epidemics and possible spread of the virus. The World Health Organisation has defined laboratory diagnostic criteria such as Positive serology, positive PCR, positive skin biopsy, and positive virus isolation. Suspected cases that are confirmed by the laboratory tests are isolated for observation (Trevor, MacNeil, and Balinandi et al. 2012). People who come into contact with infected people are isolated and quarantined for observation. Individuals who experience symptoms similar to those of Ebola in an infected region are subjected to laboratory tests to confirm the symptoms. In case of an outbreak, health officials must find and isolate all probable cases together with people who have come into contact with suspected cases. Routine surveillance is performed where the disease has been reported previously to minimize the probability of re-occurrence and limit the spread in case of an outbreak. Health officials conduct follow up assessments on survivors to determine the probability of re-infection (Hu, Trefethen, Zeng et al. 2011). The disease is controlled through isolation of suspected cases and performance of diagnostic on people who die of Ebola related symptoms. Health ministries in countries stricken by the virus conduct continuous research and surveillance to reduce the occurrence of the disease. The World Health Organization has drafted guidelines regarding health education and promotion regarding Ebola. The health officials in these countries utilize the media to enlighten the public regarding the symptoms and modes of transmission of the disease. Health officials conduct seminars to train health workers on how to identify cases of Ebola and isolate them in order to curb the spread of the virus. Health officials are trained on how to attend to Ebola cases to reduce the number of deaths. Health education in countries susceptible to Ebola has taken the center stage as the government tries to enlighten citizens on how to identify suspected cases of Ebola. Residents are trained on how to look after patients suffering from Ebola and on how to minimize contact with infected people (Leory, Gonzalez and Baize, 2011). After the Kikwit outbreak of 1996, the World Health Organization held an international conference that attracted scientists and health officials from different countries. According to WHO, the spread of the virus can only be stopped by quick containment. The government should provide protective clothing to medical personnel attending to Ebola cases. The rapid spread of disease through medical personnel is attributed to contact between patients and health workers. The health policy requires health officials to have the necessary equipment and resources for quick containment of the virus. CCD, USAID, and WHO provide funding assistance to governments where the virus has been reported for the establishment of research centers and laboratories. This helps health officials conduct fast diagnostics and research on disease trends when there is an outbreak of Ebola. CDC has also provided guidelines and assists in research activities on Ebola virus (Nidom, Nakayama, Alamudi, et al. 2011). References Barrett, A. D. T., and Stanberry, L. R. 2008. Vaccines for biodefense and emerging and neglected diseases. Amsterdam: Academic. Colfer, C. J. P. 2008. Human health and forests: a global overview of issues, practice and policy. London: Earthscan. Cook, G. C., Zumla, A., and Manson, P. 2009. Manson's tropical diseases. Edinburgh: Saunders. Dry, S., and Leach, M. 2010. Epidemics science, governance, and social justice. London: Earthscan. Dworkin, M. S. 2011. Cases in field epidemiology: a global perspective. Sudbury: Jones & Bartlett Learning. Halfmann, P. J. 2008. Novel strategies to combat Ebolavirus. Thesis (Ph.D.)-- University of Wisconsin--Madison, 2008. Hewlett, B. S., and Hewlett, B. L. 2007. Ebola, culture, and politics: the anthropology of an emerging disease. Belmont: Thomson Higher Education. Holtz, C. 2008. Global health care: issues and policies. Sudbury: Jones and Bartlett Publishers. Hu, L., Trefethen, J.M., Zeng, Y., et al. 2011. Biophysical characterization and conformational stability of Ebola and Marburg Virus-like particles. Journal of pharmaceutical sciences, 100(12), 5156-5173. Khardori, N. 2006. Bioterrorism Preparedness Medicine - Public Health - Policy. Weinheim: Wiley-VCH. Leory, E.M., Gonzalez, J.P., and Baize, S. 2011. Ebola and Marburg Hemorrhagic fever viruses: major scientific advances, but a relatively minor public health threat for Africa. Clinical microbiology and infection, 17(7), 964-976. Nelson, K. E., and Williams, C. M. 2007. Infectious disease epidemiology: theory and practice. Sudbury: Jones and Bartlett Publishers. Nidom, C.A., Nakayama, E., Alamudi, M.Y., et al. 2011. Serological Evidence of Ebola Virus Infection in Indonesian Orangutans. PLos ONE, 7(7), 1-7. Stimola, A. 2011. Ebola. New York: Rosen Pub. Trevor, S., MacNeil, A., Balinandi, S et al. 2012 Reemerging Sudan Ebola Virus Disease in Uganda, 2011. Emerging Infectious Diseases, 18(9), 1480-1483. Read More