There are millions of vacation destinations to visit this summer and thousands of sights to see, but there is one surefire way to ruin your trip — getting sick. Although you may not be thinking about viruses and bacterial infections when you plan your trip, there are a few nasty bugs you should be aware of as you pack your bags.

Dr. Scott Weisenberg, director of the Travel Medicine Clinic of the Division of Infectious Diseases at NewYork-Presbyterian Hospital/Weill Cornell Medical Center, offers the following step-by-step guide to help you stay healthy and active in whatever corner of the world you may find yourself this summer.

Before You Get There:

• Get vaccinated. See a doctor experienced in travel medicine to determine if you need vaccines against illnesses such as yellow fever, typhoid and hepatitis A.
• Get medications. If you are traveling to a malaria-containing region, medications can significantly reduce the chance of infection with this serious disease.
• Avoid blood clots. If you are on a long flight you should try to stand up and walk and/or stretch for several minutes every hour or so, to avoid blood clots that can form in your legs.
• Control jet lag. Eat light during your flight, and avoid alcohol and caffeine. Sunlight exposure after arrival can help ease adjustment to the new time zone.
• Stay hydrated. Travelers frequently become dehydrated during long flights. Drink fruit juices or bottled water to prevent dehydration during your flight.

While on Vacation:

• Don't drink the water. It is wise to heed this common warning and stay away from drinking tap water while on vacation. It is also important to refrain from using tap water in any way,including: in ice, in mixed drinks, and brushing your teeth with tap water.
• Avoid rare or raw meat or fish. Eat meat that is thoroughly cooked. You should also steer clear of raw vegetables including salads and fruits that do not have a thick, disposable outside covering.
• Be wary of local dairy products. You should be cautious about dairy products sold by small, independent vendors, and avoid any dairy products that seem to have been left out in the sun.
• Don't get bitten. Use insect repellents to reduce the chances of infection with insect-transmitted diseases such as malaria and dengue fever. Use a bed net at night if you are in a malaria region.

So You Got Sick Anyway:

• Consult a physician. If you have any of the following symptoms you should seek medical attention immediately: bloody diarrhea, severe abdominal pain, high fever or dehydration.
• Ease the symptoms on your own. To ease the symptoms of diarrhea while on vacation, try an over-the-counter medication such as Pepto Bismol or Imodium, which come in various forms and you can pack in your suitcase beforehand.

For more information on the NewYork-Presbyterian Hospital, visit http://nyp.org