Influenza, commonly called the flu or trangkaso, is a contagious viral disease. Vaccination for influenza should be done annually since the different strains mutate regularly. Remember that flu vaccines are valid only for the year they are released. So as soon as the latest annual flu vaccine is out, even if you just got vaccinated a few months back, you'll need to go back to your doctor for the new shots. The best time to get the flu vaccine is between February to June to prepare for the rainy season and cold months which is flu season.
Typhoid fever or typhoid is caused by the bacterium Salmonella enterica serovar Typhi. If you're a fan of street food, the typhoid vaccine is for you. It is transmitted by the ingestion of food or water contaminated with the bacteria. Typhoid is characterized by a sustained fever as high as 40 °C, profuse sweating, gastroenteritis, and non-bloody diarrhea. Typhoid is strongly endemic in the Philippines meaning it's very common here.
Meningococcal disease is a serious illness caused by a viral or bacterial infection. The bacteria are spread through the exchange of respiratory and throat secretions (i.e. coughing, kissing). Meningitis is an infection of fluid surrounding the brain and the spinal cord. Meningococcal vaccine is sometimes required for college freshmen living in dormitories in the U.S. as well as U.S. military recruits. It's recommended for travelers, especially backpackers, who frequent dormitories and hostels or common places in general such as congested markets and crowded areas, especially in South America and Sub-Saharan Africa.
Cholera is an infectious gastroenteritis caused by the bacterium Vibrio cholerae. Just like typhoid, transmission happens through eating food or drinking water contaminated with the bacteria. So again, if you're visiting a country known to have cholera and can't live without trying the local food, then make sure you get shots. Incidences of cholera increase as a result of floods.
Hepatitis A is an acute infectious disease of the liver caused by the Hepatitis A virus. Another virus commonly transmitted by ingestion of contaminated food or drinking water, vaccine is a must for frequent travelers.
Update (03/18/2013): Here is information on yellow fever vaccination.
Here in the Philippines, there are clinics which specialize in preventive medicine. This afternoon, I was at Immunizers, a medical clinic for vaccination services, to get my flu shots. I also had a blood test to determine whether I still need vaccination for Hepatitis and I'll know the results tomorrow. If you're a frequent traveler, it might be convenient for you to get vaccinated. It's better to be safe than sorry while on a trip. Always remember that an ounce of prevention is worth a pound of cure.
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