Public Health and Disease Notes

Terms Relating to Disease Public health – the patient is the population Epidemiology - the study of the incidence, distribution and determinants of an infection, disease or other health-related event in a population. Epidemiology can be thought of in terms of who, where, when, what, and why. That is, who has the infection/disease, where are they located geographically and in relation to each other, when is the infection/disease occurring, what is the cause, and why did it occur.

Terms Relating to Disease Endemic – prevalent and permanent in or restricted to a particular locality, ex. malaria in the tropics Epidemic – “outbreak” or spread of a disease among people in a specific community Pandemic – global disease outbreak; determined by how the disease spreads, not by the number of deaths

Terms Relating to Disease Chronic - of long duration, denoting a disease of slow progress, typically non- communicable Ex: cancer, kidney disease, diabetes Acute – lasts for just a short time, but can begin rapidly and have intense symptoms Ex: colds, influenza, respiratory infections Infectious – caused by infection or capable of causing infection

Terms Relating to Disease Immunization/Vaccination - the act of inducing antibody formation leading to immunity. Vaccines - A preparation made from killed or weakened pathogens which when introduced in the body induce the production of antibodies and thus boost the body's immunity against that pathogen. Pathogen - A microbe, such as virus or bacteria, which may cause disease. Vector - An agent, usually an animal or an insect, that transmits a pathogen from one host to another. Ex. mosquitoes transmit the plasmodium that causes malaria Transmission – spreading of a communicable disease from an infected host to another person; Various ways -- droplet infection, direct physical contact, indirect physical contact, airborne, fecal-oral

Major Diseases Re-emerging Diseases - Tuberculosis - Cholera - Influenza - Malaria *Smallpox eradicated in 1980 New diseases - HIV - Hepatitis - Ebola - Avian Flu - SARS

Tuberculosis TB is second only to HIV/AIDS as the greatest killer worldwide due to a single infectious agent According the World Health Organization, in 2013, 9 million people fell ill with TB and 1.5 million died from the disease. Over 95% of TB deaths occur in low- and middle-income countries. TB is a leading killer of people living with HIV causing ¼ of all deaths About 1/3 of the world's population has latent TB, which means people have been infected by TB bacteria but are not (yet) ill with disease and cannot transmit the disease. People infected with TB bacteria have a lifetime risk of falling ill with TB of 10%. However persons with compromised immune systems, such as people living with HIV, malnutrition or diabetes, or people who use tobacco, have a much higher risk of falling ill. Spreads via ill persons through air and casual contact Multi-drug resistant TB (MDR-TB) is present in all countries surveyed by the WHO. TB is curable and preventable DOTS (Direct Observation Treatment Short Course). The TB death rate dropped 45% between 1990 and 2013.

Malaria There were about 198 million cases of malaria in 2013 and an estimated deaths Most deaths occur among children living in Africa where a child dies every minute from malaria world’s worst tropical and subtropical disease vector-borne disease – caused by plasmodium parasites that are transmitted to people through the bites of infected mosquitoes. Increased malaria prevention and control measures are dramatically reducing the malaria burden in many places Malaria is preventable and curable Some effective drugs; mosquito nets and repellent offer protection, search for effective vaccine Parasites are developing drug resistance Malaria mortality rates have fallen by 47% globally since 2000, and by 54% in the WHO African Region. However, in Africa a child dies every minute from malaria

Cholera/Diarrheal Diseases Researchers have estimated that there are 1.4 to 4.3 million cases, and 28,000 to 142,000 deaths worldwide due to cholera every year, mostly in lesser developed countries. Among people who develop symptoms, 80% have mild or moderate symptoms, while around 20% develop acute watery diarrhea with severe dehydration. This can lead to death if left untreated. Again, particularly dangerous for children caused by ingestion of food or water contaminated with the bacterium Vibrio cholerae. Outbreaks are typically caused by a contaminated water supply Easily treatable with oral rehydration salts Provision of safe water and sanitation are critical to control outbreaks

Cholera cont. Cholera transmission is closely linked to inadequate environmental management. Typical at-risk areas include urban slums, where basic infrastructure is not available, as well as camps for internally displaced people or refugees, where minimum requirements of clean water and sanitation are not met. The consequences of a disaster – such as disruption of water and sanitation systems, or the displacement of populations to inadequate and overcrowded camps – can increase the risk of cholera transmission should the bacteria be present or introduced. Haiti after earthquake of 2010 – 350,000 cases and 5,400 deaths During the 19th century, cholera spread across the world from its original reservoir in the Ganges delta in India. Six subsequent pandemics killed millions of people across all continents. The current (seventh) pandemic started in South Asia in 1961, and reached Africa in 1971 and the Americas in Cholera is now endemic in many countries.

Influenza acute viral infection that spreads easily from person to person and circulates worldwide and can affect anybody in any age group. causes annual epidemics that peak during winter in temperate regions. An epidemic can take an economic toll through lost workforce productivity, and strain health services. Seasonal flu - mutations (antigenic drift) occur almost yearly, vaccinations are needed Pandemic flu – mutations (antigenic shift) occur when two different flu strains combine and it can be disastrous. Ex. -“Spanish flu” of killed more people than all of WWI, killed million people, most deadly pandemic the world has ever seen. Killed 2.5% of world population. Evidence now shows that the “Spanish Flu” was a strain of Avian Flu (bird flu) Came and went within 18 months Contemporary strains are less dangerous, but when recombined with bird flu strains they could be.

HIV/AIDS Human Immunodeficiency Virus/Acquired Immunodeficiency Syndrome HIV continues to be a major global public health issue, having claimed more than 34 million lives so far. In 2014, 1.2 [1.0–1.5] million people died from HIV-related causes globally. There were approximately 36.9 [34.3–41.4] million people living with HIV at the end of 2014 with 2.0 [1.9–2.2] million people becoming newly infected with HIV in 2014 globally. Sub-Saharan Africa is the most affected region, with 25.8 [24.0– 28.7] million people living with HIV in Also sub-Saharan Africa accounts for almost 70% of the global total of new HIV infections.

HIV/AIDS A cure for HIV infection has not been found but with effective treatment with antiretroviral (ART) drugs, patients can control the virus and enjoy healthy and productive lives. In 2014, 14.9 million people living with HIV were receiving antiretroviral therapy (ART) globally, of which 13.5 million were receiving ART in low- and middle-income countries. The 14.9 million people on ART represent 40% [37–45%] of people living with HIV globally Sub Saharan Africa – 71% of infection and 76% of deaths; 61% of infected are women; 14 million orphans Refer to articles for causes and effects, treatments, cultural, and social issues