Epidemiology of Prevention of Communicable Diseases

Excerpt

Communicable diseases are illnesses caused by viruses or bacteria that people spread to one another through contact with contaminated surfaces, bodily fluids, blood products, insect bites, or the air. There are many examples of communicable diseases, some of which require reporting to appropriate health departments or government agencies in the locality of the outbreak. Some examples of communicable diseases include HIV, hepatitis A, B, and C, measles, salmonella, measles, and blood-borne illnesses. The most common forms of spread include fecal-oral, food, sexual intercourse, insect bites, contact with contaminated fomites, droplets, or skin contact.

Specifically, hepatitis is a form of a communicable disease that is spread through the oral-fecal route. An individual is exposed to hepatitis by coming in contact with blood products, consuming contaminated water, having sex with another infected person (oral and intercourse), or eating food that is contaminated by the virus. Six criteria need to be met to diagnose a hepatitis infection. These criteria include an infection agent, in this case, the hepatitis virus, a reservoir, route of infection, transmission mode, route of entry, and a susceptible subject who becomes infected with the virus.

Hepatitis A virus (HAV) is a communicable disease preventable through vaccination. It affects the liver, causing jaundice. It is transmitted person-to-person through food consumption, oral sexual contact, poor hand hygiene after using the bathroom or changing diapers, and contaminated water. It is one of the most reported outbreaks in the United States. It is self-limited after ingestion through contaminated food sources. The virus replicates in the liver, is excreted in bile, and can reach high concentrations in the stool.

Stool concentrations are the highest 2 weeks after transmission. Patients are considered non-infectious about a week after inoculation or the onset of jaundice. Patients who are symptomatic most often present with acute onset fever, malaise, jaundice, hepatomegaly, and abdominal pain. Jaundice is often followed by marked elevated serum aminotransferases that are greater than 1000 units/L. The test of choice is IgM anti-hepatitis A virus for diagnostic purposes. There is no specific therapy available. Presently, supportive and conservative management is the mainstay of treatments. Prevention includes personal hygiene or active or passive immunization.