Infectious & Communicable Diseases

From the earliest confirmed case of tuberculosis in ancient Egypt to the H1N1 pandemic of 2009, infectious diseases have always been a part of human life. They can result in something as minor as a runny nose or as severe as death within hours. They kill 14 to 17 million people every year worldwide. Modern travel makes it easy for these bugs to find their way to every continent in the world. Modern medicine and careful precautions make it easier to contain and treat outbreaks.

Types

• There are many agents that can cause infectious diseases, but most fall into one of four categories: viruses, fungi, bacteria and parasites. Viruses require a host to replicate but can survive outside a body for up to several hours. The common cold, influenza, Ebola and HIV are viruses. Bacteria are single-celled organisms slightly larger than viruses. Unlike viruses, they can reproduce asexually and do not require a host to survive. Bacterial infections include bacterial meningitis, E. coli, Lyme disease, salmonella and strep. The Black Death was caused by a bacteria called yersinia pestis. Fungi are larger than other infectious agents and are most often found in soil, plants, animals and on the skin. Yeast infections, athlete's foot and ringworm are types of fungal infections. Parasites are tiny organisms that feed off another living organism. Parasitic infections include tape worm, toxoplasmosis, trichinosis and malaria.

Symptoms

• Symptoms vary greatly depending on the infectious agent but most cause fever, loss of appetite, body aches and fatigue. Some cause little or no symptoms. HIV and the virus that causes Lyme disease can live in a host for years before causing illness. Trichinosis and salmonella can cause vomiting and diarrhea while some athlete's foot and yeast infections may cause itching. At the extreme end of the spectrum, hemorrhagic fevers like Ebola can causes bleeding from every orifice of the body.

Transmission

• Infectious diseases can be spread in a number ways. Human to human transmission can happen through direct contact or droplets from coughs and sneezes. Animals can infect humans through bites, scratches and contact with their feces or urine. Insects carry numerous infectious agents, including malaria and Lyme disease. Ingesting contaminated food can cause salmonella, E. coli and tape worm. Some infections can be acquired by simply touching a doorknob previously touched by an infected person and rubbing your eyes afterward.

Treatment

• Treatments depend on the cause of the infections. Bacterial infections can be treated with antibiotics. However, overuse of antibiotics has led to the creation of drug-resistant strains. Methicillin-resistant Staphylococcus aureus (MRSA) is a prime example. Fungi are treated with topical or oral antifungals. Antiparasitics combat parasites. Viruses are the hardest to treat. While there are some antiviral drugs for certain types such as HIV and influenza, most viruses do not have a treatment. Treatment for those types often involves strengthening the immune system's response through intravenous immunoglobulin (IVIG), a protein used by the body to create antibodies.

Prevention

• Many infectious agents can be prevented very easily through good personal hygiene practices and a little forethought. Wash your hands frequently, particularly after using the toilet and before and after preparing food. Practice safe sex. Don't share your toothbrush. Stay home when you are sick. Vaccines are available for several infectious diseases including polio, measles, mumps, rubella, tetanus and the flu. Before traveling to exotic locations, find out which diseases are prevalent there and get immunized if possible.