DISEASE Biological Hazards

2 Catagories of Disease Nontransmissible disease- caused by something other than living organisms and does not spread from one person to another. Examples: heart disease, most cancers, diabetes, emphysema, malnutrition. Transmissible disease- caused by a pathogen(bacteria, virus, protists, parasite) and can be spread person to person. Spread by air, water, body fluids, or some other vector (mosquitos, etc.).

World Health Organization (WHO) data 30% of deaths caused by cardiovascular diseases. 26% of deaths caused by infectious disease. 12% of deaths caused by cancers.

Epidemiological Transition As a country industrializes it goes from deaths due to transmissible, infectious type diseases of child hood to non transmissible type disease of adulthood. Deaths due to transmissible disease has been greatly reduced since 1900 due to the use of vaccines, antibiotics, and overall better health care.

Problems: Many bacteria have developed immunity (genetic resistance) to current antibiotics. Also many vector insects have developed immunity to pesticides. World travel is increasing the spread of infectious disease.

The 3 most dangerous viruses HIV- causes AIDS which kills about 3 million people per year. Spread mainly by unsafe sex practices. Influenza virus which kills about 1 million people per year. Spread by body fluids and airborne water droplets. Hepatitis B virus which kills about 1 million people per year. Spread by unsafe sex practices. SARS virus, Ebola virus and West Nile virus are also noteworthy.

Case Study: Tuberculosis TB is caused by a bacterium spread by airborne water droplets from coughing and sneezing. 1 in 3 people are infected by TB worldwide. 9 million people a year die from TB. Symptoms are not manifested in many individuals causing them to act as vectors without knowing it. There is a serious lack of TB screening in developing countries. Can be cured using relatively inexpensive drugs used for 6-8 months. Symptoms abate after a few weeks and when drugs are discontinued the remaining live bacteria develop resistance. Many strains of the TB bacterium have developed resistance to antibiotics.

Case Study: HIV HIV infects and destroys human immune cells leaving the body susceptible to deadly diseases like pnuemonia and cancers. Everyday about 14,000 people are infected by HIV. Over 90% of infected people live in developing countries, especially African. Because of a long incubation period, the disease is spread without an individuals knowledge for up to 10 years. Political action can slow the spread of AIDS in a country.

Case Study: Malaria Malaria kills about 1 million people per year. Caused by a protozoan carried by a mosquito vector found in tropical environments. It infects and destroys red blood cells causing fever, chills, abdominal pain, headaches, vomiting, susceptibility to other diseases, and death. Malaria has killed more people than all wars combined. Malaria spreading mosquitoes have become resistant to many pesticides and the plasmodium protists has become resistant to many drugs. Controlling the spread of mosquitoes is the best current method for controlling the spread of malaria.