By Dr. Jeff Daniels EBS Medical Columnist

Now that ski season is over, it’s time to make plans to travel, and those plans might take you to some pretty exotic places. That raises the possibility of exposure to various infections that we’re not used to here in Montana.

Travel doesn’t have to be international to increase the risk of acquiring an infection. There are certain parts of the United States that offer recreation in an environment where certain infections are rampant. One area to keep in mind is Tennessee and Missouri. These states have become the epicenter for tick-borne illnesses, including Lyme disease, Ehrlichiosis and anaplasmosis. These are bacterial infections spread by ticks and can cause acute, but also chronic, illness.

Lyme disease involves a circular rash where the tick bite occurred, followed by a variety of problems like knee swelling, infection of heart tissues and neurological problems. Ehrlichiosis and anaplasmosis present with fever, headache and malaise, liver damage and blood cell damage. Avoiding tick bites by using a good DEET tick repellant and checking your skin after being outdoors is the best way to prevent these illnesses, but if suspected, doxycycline is used to treat all three.

As global warming increases and areas in the southern United States with subtropical conditions expand, infecting organisms like bacteria and viruses—as well as the vectors that spread them—are becoming more common. Three mosquito-borne flavovirus infections have been making the news: Dengue fever, Chikungunya and Zika virus infection. These three are predominantly confined to tropical countries, but they’re starting to be reported more in Florida and along the Gulf Coast.

Referred to as “breakbone fever,” Dengue fever can cause tremendous pain in the bones, a rash, headache and malaise. It usually clears after a week or two, but in some unlucky individuals who have been exposed to Dengue numerous times, the immune system begins to attack the circulation and hemorrhaging results.

Chikungunya is similar to Dengue (without the hemorrhagic complications), but can result in chronic joint pain, lasting months or years. You’ve likely heard about the birth defects caused by Zika virus infection. That should make anyone pregnant or thinking about getting pregnant avoid areas where Zika is prevalent. Most cases of Zika in adults are asymptomatic, but in some it is confused with Dengue fever.

When traveling outside the U.S., it’s important to check the Centers for Disease Control and Prevention website to find out which vaccinations are necessary or required, and what you might be up against. Most importantly, figure out if you will need to take prophylactic medication to prevent malaria.

If you happen to be traveling to sub-Saharan Africa or the Amazon basin, you’ll have to consider another mosquito-borne flavovirus that causes yellow fever. The virus most often causes minor symptoms, but one out of six people exposed to it will get extremely ill, and some yellow fever epidemics have had a 90 percent mortality rate.

We have a vaccine to prevent yellow fever, but it’s in very short supply until Sanofi-Pasteur, the U.S. manufacturer, completes its new facility in mid-2018. The vaccine is currently being imported from France, and it’s distributed sparingly. If you think you might be traveling to a place where you’ll need it, give yourself plenty of time between your doctor visit and your trip since it takes 10 days to become immune once you’ve been administered the shot.

Yellow fever vaccine is relatively safe, although there are more side effects for travelers over age 60. It used to be recommended every 10 years for those visiting areas where it’s endemic, but it’s now thought that one shot gives lifetime protection.

Finally, we recommend that any traveler going to a developing country get vaccinated for Hepatitis A, a safe intramuscular injection, and typhoid fever, a safe series of capsules to raise immunity in the gut to Salmonella typhii. One more note: If you were never given the measles or polio vaccines in childhood, you might want to consider getting vaccinated since these diseases are still out there and can do tremendous harm to those who are not vaccinated.

I hope I haven’t scared you into not leaving Big Sky!

Dr. Jeff Daniels was the recipient of the 2015 Chamber of Commerce Chet Huntley Lifetime Achievement Award and has been practicing medicine in Big Sky since 1994, when he and his family moved here from New York City. A unique program he implements has attracted more than 800 medical students and young doctors to train with the Medical of Big Sky.