Basically it causes very painfull muscle spasms and cramps. Diphtheria - caused by a bacillus bacteria that invades tissues in the upper respiratory tract and releases toxins that are potentially fatal. Diphtheria may be treated or vaccinated against. After an initial course of three injections, boosters are necessary every 10 years. Encephalitis - an infection of the brain, often caused by viruses transmitted by ticks or mosquitoes.
Vaccines are available for Japanese encephalitis and the tick-born encephalitis found in Asia.
Encephalitus is not of great risk to travelers. Consider the vaccination if spending a month or longer in a high risk area, making repeated trips to a risk area or visiting during an epidemic. It involves three injections over 30 days. The vaccine is expensive and has been associated with serious allergic reactions so the decision to have it should be balanced against the risk of contracting the illness. Hepatitis A is not life threatening, but unpleasant, and is transmissible by food and water.