IDS 224: Disease Prevention: Specific Diseases

Measles is a highly contagious infectious disease caused by the measles virus. Symptoms usually develop 10–12 days after exposure to an infected person and last 7–10 days. Initial symptoms typically include fever, often greater than 40 °C (104 °F), cough, runny nose, and inflamed eyes. Small white spots known as Koplik's spots may form inside the mouth two or three days after the start of symptoms. A red, flat rash which usually starts on the face and then spreads to the rest of the body typically begins three to five days after the start of symptoms. Common complications include diarrhea (in 8% of cases), middle ear infection (7%), and pneumonia (6%). These occur in part due to measles-induced immunosuppression.[6] Less commonly seizures, blindness, or inflammation of the brain may occur.

Before the vaccine was available in the 1960s between three and four million cases occurred each year. With consistent widespread childhood vaccination, this figure fell to 13 cases per million by the 1980s, and to about 1 case per million by the year 2000, at which time the U.S. was declared free of circulating measles. A resurgence of measles occurred in the U.S. in 2018 & 2019 with the most recent numbers of confirmed cases reaching 1,282 individuals in 31 states. In the Congo, an outbreak caused nearly 5,000 deaths and 250,000 infected individuals, with most deaths occurring among children under five years of age.

Dengue fever is a mosquito-borne tropical disease caused by the dengue virus. Symptoms typically begin three to fourteen days after infection. These may include a high fever, headache, vomiting, muscle and joint pains, and a characteristic skin rash. Recovery generally takes two to seven days. In a small proportion of cases, the disease develops into severe dengue, also known as dengue hemorrhagic fever, resulting in bleeding, low levels of blood platelets and blood plasma leakage, or into dengue shock syndrome, where dangerously low blood pressure occurs. Each year between 50 and 528 million people are infected and approximately 10,000 to 20,000 die.

Ebola virus disease (EVD) is a viral hemorrhagic fever of humans and other primates. Signs and symptoms typically start between two days and three weeks after contracting the virus with a fever, sore throat, muscular pain, and headaches. Vomiting, diarrhea and rash usually follow, along with decreased function of the liver and kidneys, and at this time some people begin to bleed both internally and externally. The disease has a high risk of death, killing 25% to 90% of those infected, with an average of about 50%. This is often due to low blood pressure from fluid loss, and typically follows 6 to 16 days after symptoms appear.

Cholera is a bacterial infection of the small intestine by some strains of the bacterium Vibrio cholerae. Symptoms include large amounts of watery diarrhea that lasts a few days and may lead to severe dehydration and electrolyte imbalance, vomiting and muscle cramps, sunken eyes, cold skin, decreased skin elasticity, and wrinkling of the hands and feet. Dehydration can cause the skin to turn bluish. Symptoms start two hours to five days after exposure, and may range from none, to mild, to severe.

Hepatitis is inflammation of the liver tissue most commonly caused by Hepatitis viruses A, B, C, D, and E. Since outbreaks were first identified in 2016 in the U.S., 32 states have publicly reported the following as of January 25, 2020: 30525 cases, 18,604 hospitalizations (61%), and 306 deaths. Some people with hepatitis have no symptoms, while others develop jaundice, poor appetite, vomiting, tiredness, abdominal pain, and diarrhea, and progress to chronic hepatitis, or (rarely) scarring of the liver (cirrhosis) or even liver failure or liver cancer.

Zika virus (ZIKV) is a member of the virus family Flaviviridae, and is related to dengue, yellow fever, West Nile, and Japanese encephalitis. It is spread by daytime-active Aedes mosquitoes. The infection runs similar to a fever, and often causes no or only mild symptoms. It can spread from men and women to their sexual partners, and from pregnant women to her unborn baby. Babies may be born with microcephaly, severe brain malformations, Guillain–Barré syndrome, or other birth defects. The illness cannot be prevented by medications or vaccines. It was estimated that 1.5 million people were infected by Zika in Brazil, with over 3,500 cases of microcephaly reported between October 2015 and January 2016.

Bubonic plague is one of three types of plague caused by bacterium Yersinia pestis: Bubonic, Septicemic, and Pneumonic. One to seven days after exposure to the bacteria, flu-like symptoms develop including fever, headaches, and vomiting. Swollen and painful lymph nodes occur in the area closest to where the bacteria entered the skin. Occasionally, the swollen lymph nodes may even break open.

Bird flu is similar to swine flu, dog flu, horse flu and human flu in that the illness is caused by strains of influenza viruses that have adapted to a specific host, but has adapt and can be transfer to different species. For example, pigs can also be infected with human, avian, and swine influenza viruses, allowing for mixtures of genes (reassortment) to create a new virus, which can cause an antigenic shift, essentially creating a new influenza A virus subtype which most people have little to no immune protection against. The first reported human infection was in 2013 in China.

The new (H1N1)pdm09 virus contained a unique combination of influenza genes not previously identified in animals or people. Unlike the avian flu and SARS (H5N1) which provoke a runaway body-wide immune response, H1N1/09 destroys the lungs' alveoli, often causing acute respiratory distress syndrome, which kills in half of all cases. The CDC estimated 60.8 million cases, over 274,000 hospitalizations, and 12,469 deaths in the US. This is sometimes compared to the 36,000 people per year who die from the "common flu," mostly in winter.

Severe Acute Respiratory Syndrome (SARS) is a viral respiratory disease of zoonotic origin caused by the SARS coronavirus (SARS-CoV). An outbreak of SARS in China (2002) lead to 8,098 SARS cases, and killed 774 individuals in 17 countries. The fatality rate for SARS was 9.6% according to the World Health Organization (WHO). The last case of SARS was reported in 2004. In late 2017, Chinese scientists traced the virus through the intermediary of civets to cave-dwelling horseshoe bats in Yunnan province. Initial symptoms are flu-like and may include fever, muscle pain, lethargy symptoms, cough, sore throat, and other nonspecific symptoms. The only symptom common to all patients is a fever above 38 °C (100 °F). SARS may cause shortness of breath and pneumonia, and is known to be followed by pneumonia. The average incubation period for SARS is 4–6 days, but can be as short as 1 day or as long as 14 days.

Mad Cow Disease, also known as Creutzfeldt–Jakob disease (CJD), is a fatal degenerative brain disorder. Early symptoms include memory problems, behavioral changes, poor coordination, and visual disturbances. Later symptoms include dementia, involuntary movements, blindness, weakness, and coma. Roughly 70% of people die within a year of diagnosis. This disease is caused by an infected protein known as a prion. The protein is misfolded and it causes normally folded proteins to become misfolded. There is now strong scientific evidence that the agent responsible for the outbreak of prion disease in cows is the same agent responsible for the outbreak of vCJD in humans.