An epidemic is defined as the occurrence of an illness or health-related event that is unusually large or unexpected. Epidemics are commonly caused by a disease of infectious or parasitic origin. Infectious diseases such as cholera, meningococcal meningitis, typhoid, viral hemorrhagic fever pose considerable threats to a community. The term epidemic can be applied to any pronounced rise in the occurrence of a disease and is not restricted to sudden outbreaks.
Based on data and statistics from 1980-2008 the number of people killed by epidemics was 183,278 people and the number of people affected was 19,411,394. Based on International Federation of Red Cross and Red Crescent Societies, epidemic is categorized as biological hazards. An epidemic is then unusual increase in the number of cases of an infectious disease which already exists in a certain region or population. It can also refer to the appearance of a significant number of cases of an infectious disease in a region or population that is usually free from that disease. Epidemics may be the consequence of disasters of another kind, such as tropical storms, floods, earthquakes, droughts, etc. Epidemics may also attack animals, causing local economic disasters.
The classification of epidemic on this guide is based on International Federation of Red Cross and Red Crescent Societies (IFRC).
Avian influenza (AI) is a viral infection primarily affecting birds (chickens, ducks, geese etc., both domestic and migratory species), but also sometimes other species such as pigs and tigers. Rarely, bird flu can cause severe infections in humans. There are many different strains or varieties of AI viruses. They are a sub-group of influenza viruses, which includes the flu virus that causes seasonal outbreaks in humans around the world every year.
See more details about Avian Flu in IFRC page.
Cholera is mainly spread by drinking water contaminated by faeces. The fatality rate for severe, untreated cases is 50 per cent; when treated this drops to one per cent. The incubation period is 1-12 days and severe cases need hospitalisation. Less severe cases can be treated with rehydration therapy on an outpatient basis. Only 10 per cent of those infected present symptoms.
See more details about Cholera in WHO page.
Dengue or breakbone fever and dengue haemorrhagic fever are transmitted by "day biter" mosquitoes. Dengue fever is rarely fatal; the haemorrhagic variety, if untreated, can result in a 40-50 per cent mortality rate. With hospital care and fluid therapy, this can be brought to below five per cent.
Ebola and Marburg
Two distinct viral diseases with similar symptoms. Both have a high fatality rate (up to 90 per cent for Ebola) and are extremely contagious - transmission is through contact with all body fluids and organs, use of contaminated needles and syringes, and the aerosol route. Extraordinary precautions should be taken to prevent contamination of all those involved in assisting patients. The reservoir of the two viruses is unknown.
Malaria is transmitted by the bite of the anopheles mosquito, a dusk to dawn biter. Where the disease is endemic, the local population has some degree of immunity. The people at greatest risk are those from a non-malarial area, such as IDPs or refugees. They can be protected by a weekly dose of a malaria suppressive drug. Of the four types of malaria, falciparum can be rapidly fatal and needs prompt treatment.
See more details about Malaria in IFRC page.
This is a highly communicable viral infection that can result in a very high mortality rate, especially among children and undernourished populations. A prompt and comprehensive vaccination program at the start of an outbreak can help limit its spread. If vaccine supplies are limited, the first priority is malnourished and hospitalized children, the next priority six-month to two-year-old children. A reliable cold chain is essential for vaccine storage. Isolation or quarantine is impractical.
See more details about Measles in IFRC page.
Meningococcal Meningitis is an acute bacterial disease. Epidemic waves occur at irregular, unexplained intervals. Chiefly affects children and young adults, especially those in crowded living conditions. The disease is transmitted by direct contact with nose and throat discharges. Infected individuals should be separated from others and their immediate contacts put under close health surveillance.
Yellow fever is a deadly and fast-spreading mosquito-borne virus occurring only in parts of Africa and South America. The disease is highly communicable. Action to control an epidemic should include mass vaccination of people at risk; screening and spraying of patients' rooms or hospital wards to prevent mosquito access; elimination or use of larvicide on all existing or potential mosquito breeding sites; spraying with insecticide of all houses in the community. Vaccination provides a ten-year immunity.
See more details about Yellow Fever in WHO page.
HIV/AIDS (Human Immunodeficiency Virus/Acquired Immune Deficiency Syndrome) will kill more people this decade that all the wars and disasters in the past 50 years. Since the AIDS epidemic began, 25 million people have died and more than 40 million are now living with HIV and AIDS. In 2001 alone, five million people became infected worldwide.
See more details about HIV/AIDS in IFRC page.
Tuberculosis (TB) is the single most deadly infectious disease and kills two million people each year. Of the eight million new cases annually, 95 per cent are in developing countries. Asia and sub-Saharan Africa are the hardest hit, but Eastern Europe has recently seen a major increase in the incidence and deaths related to TB after many years of steady decline. An estimated 75 per cent of people with TB are between the ages of 15-44, which is seriously damaging socio-economic development.
See more details about Tuberculosis in IFRC page.
The immediate effect of epidemics is of course that they cause illness and death. Secondary effects are social and political disruption and economic loss. Epidemics may worsen already traumatic or life-threatening situations such as those found in famine situations and in IDP/ refugee camps. Based on Piere County Washington document on epidemic, there are two different original causes of epidemic which are animal and human epidemic. The effects of animal epidemics include such diverse problems as: economic loss; loss of food supply such as the possible loss of meat and/or dairy products and animal byproducts such as wool; and the loss of recreation. Another possibility of animal epidemic is transferable to human population.
The impacts of human epidemics include loss of life or either short or long term debilitation for the victims. It could include economic hardship; lost work time affects not only the employee, but also the employer, loss of productivity due to individual illnesses is a major business problem.
Learn also the effect of the AIDS epidemic on economic welfare in Sub-Saharan Region.
Mitigation on this guide is based on mitigation action for animal and human epidemic, because both the source of epidemics is still a risk for human being. For animal epidemics, first, increasing compliance with the health or rabies certificate requirements would go a long ways towards prevention. Second, vaccinating animals in an effort to prevent diseases within the local populations should be considered.
Mitigation for human epidemic include to: maintain sewage and waste disposal systems; promote and fund both childhood and adult immunization programs; support and provide health education in the schools and on a community level to address disease transmission and prevention; target the mechanism of transmission of individual diseases, such as drug usage for diseases like HIV infection and Hepatitis B; maintain strict health standards for food service employees and eating establishments; maintain strict health standards for food products; utilize accepted and recommended infection control practices in medical facilities. The community education programs should be targeted in particular at high risk groups for blood born pathogens and sexually transmitted diseases.
Several actions related to epidemic management planning.
2. Framework of Government’s Preparedness Plan for Influenza Pandemic in Hong Kong. (click here)