Diphtheria is caused by a bacterium, Corynebacterium diphtheriae. The actual disease is caused when the bacteria release a toxin, or poison, into the person's body.
Diphtheria bacteria live in the mouth, throat, and nose of an infected person and can be passed to others by coughing or sneezing. Occasionally, transmission occurs from skin sores or through articles soiled with discharge from sores of infected persons.
Malaria is the most significant parasitic disease threat you will face in most tropical and subtropical countries. It is a microscopic blood- borne parasite transmitted to humans by the bites of infected mosquitoes. There are 300 to 500 million cases a year of malaria worldwide —approximately 1000 a year are reported in U.S. travelers.
Barotrauma is discomfort in the ear caused by pressure differences between the inside and the outside of the eardrum.
The air pressure in the middle ear is usually the same as the air pressure outside of the body. If the eustachian tube (the connection between the middle ear and the back of the nose and upper throat) is blocked, the air pressure in the middle ear will be different than the pressure on the outside of the eardrum, causing barotrauma.