Rising Infectious Disease Threats Highlight Importance of Travel Vaccines

As international travel increases, so does the risk of exposure to infectious diseases. Global mobility, climate change, and lapses in vaccination coverage have fueled the resurgence and spread of illnesses such as measles, chikungunya, and chagas disease.

For travelers, vaccination remains one of the most effective ways to reduce risk, both for personal protection and to prevent the importation of infectious diseases across borders.

Miniature traveler looking for vaccine | Image Credit: © Yuan - stock.adobe.com

Which Diseases Are Circulating?

Several infectious diseases continue to circulate globally, presenting risks to unvaccinated or underprepared travelers. Some, like measles, are resurgent even in countries with historically strong immunization programs. For example, the US is experiencing the largest measles outbreak since 2000, totaling over 1400 cases. According to global health reporting, surges in measles cases are present in every region on the planet including Europe, Africa, Asia, Central and South America, and Canada—a result of declining immunization rates.^1-6

As global temperatures rise, other diseases spread by insects are becoming more prevalent in regions where they previously were not. For example, rising temperature create the ideal environment for mosquitos, who can carry a host of diseases. Most notable, chikungunya is spreading rapidly in China, Latin America, and Europe—areas which have not seen such outbreaks in the past.⁷

Chagas disease, originally endemic to Mexico and Central and South America, is now regularly circulating in the US, according to a report published by the CDC. California is experiencing the highest rate of cases at anywhere between 70,000 and 100,000. Human cases have also been reported in Arizona, Texas, Louisiana, Missouri, Tennessee, and Arkansas. However, the risk is widespread with kissing bugs found across all states.^8,9

The CDC also reports increasing rabies cases in the US driven by habitat loss and lack of vaccination. As natural habitats shrink, contact between humans and wild animals grows more frequent, increasing the risk of diseases such as rabies. As of September 2025, the CDC reported 6 deaths from rabies in the US, marking the highest number in years. These cases were connected to exposure to rabid animals including raccoons, skunks, and gray foxes. Affected areas including Nassau County, New York; Cape Cod, Massachusetts; and parts of Alaska, Arizona, California, Indiana, Kentucky, Maine, North Carolina, Oregon, and Vermont.¹⁰

“We are currently tracking 15 different likely outbreaks,” Ryan Wallace, MD, leader of the rabies team at the Centers for Disease Control and Prevention, told NBC News.¹⁰

What Are the Vaccine Recommendations?

For measles, the CDC recommends that all travelers are fully vaccinated with the measles, mumps, and rubella (MMR) vaccine. Children should receive 2 doses, the first at 12 to 15 months of age and the second at 4 to 6 years. Adults without evidence of immunity should also be vaccinated, particularly those at higher risk such as international travelers, health care workers, and college students. Infants as young as 6 months who are traveling internationally should receive a dose before departure, although this dose does not count toward the routine series. Vaccination should be done about 2 weeks prior to travel.^11,12

Chikungunya vaccines are available in the United States, but the live-attenuated vaccine Ixchiq (Valneva) has had its US biologics license suspended by the FDA. As of August 22, 2025, use of Ixchiq was halted after reports of serious adverse events, including hospitalizations, neurologic issues, and at least 1 death from vaccine strain encephalitis. The remaining vaccine, Vimkunya (Bavarian Nordic), is a virus-like particle vaccine approved for individuals 12 years and older and continues to be available.^13,14

The CDC recommends vaccination for travelers going to areas with current chikungunya outbreaks, and for long-term stays or moves to regions where the virus is endemic. Special caution is advised especially for older adults (initially ≥60 or ≥65), those with chronic medical conditions, immunocompromised people, and pregnant or breastfeeding individuals.^13,14

For rabies, the CDC advises pre-exposure prophylaxis (PrEP) for travelers to countries where rabies is common and where timely access to post-exposure treatment may be limited. In 2022, the Advisory Committee on Immunization Practices updated recommendations to a 2-dose vaccine series given on days 0 and 7, replacing the previous 3-dose schedule. Pre-exposure vaccination is also recommended for veterinarians, animal handlers, and other high-risk groups. In the event of an exposure, those who are unvaccinated require immediate wound care, rabies immune globulin, and a vaccine series, whereas vaccinated individuals receive only a reduced vaccine series without immune globulin.¹⁵

As of 2025, Chagas disease has no vaccine or preventive drug available. The CDC stresses the importance of preventive measures such as avoiding insect bites from kissing bugs, using bed nets, and improving housing conditions in endemic areas. Blood screening and vector control efforts also remain critical to reducing transmission.⁹

Other Worthy Mentions

Several other vaccines are important to consider for international travelers. Yellow fever vaccination is required for entry into certain countries in Africa and South America and remains essential protection against outbreaks.¹⁶

Japanese encephalitis vaccination is recommended for travelers spending extended periods in rural areas of Asia, particularly during transmission seasons.¹⁷

Typhoid vaccination is advised for those traveling to areas with poor sanitation or where the disease is common, such as South Asia, parts of Africa, and Latin America.¹⁸

Polio remains a risk in parts of the world and outbreaks have been announced in Papau New Guinea and areas of the Middle East, particularly Gaza.^19,20

Finally, both hepatitis A and B are widely circulating globally, and vaccination is strongly recommended for travelers, particularly given the ease of transmission through food, water, blood, and sexual contact.²¹

As frontline health care providers, pharmacists play a critical role in ensuring travelers are protected against infectious diseases. By counseling patients on recommended vaccines, verifying immunization status, and providing guidance on preventive measures, pharmacists help reduce individual risk and curb the international spread of diseases. Staying up to date on CDC guidelines and emerging outbreaks helps pharmacists offer timely, evidence-based recommendations that safeguard both travelers and the communities they return to.

REFERENCES

1. Global measles outbreaks. CDC. September 10, 2025. Accessed September 17, 2025 https://www.cdc.gov/global-measles-vaccination/data-research/global-measles-outbreaks/index.html

2. Gerlach A. Measles outbreak update, Florida Surgeon General announces plan to remove vaccine mandates in schools. Pharmacy Times. September 10, 2025. Accessed September 17, 2025. https://www.pharmacytimes.com/view/measles-outbreak-update-florida-surgeon-general-announces-plan-to-remove-vaccine-mandates-in-schools

3. Hughes D. Measles holiday warning as cases rise in Europe. BBC. June 6, 2025. Accessed September 17, 2025. https://www.bbc.com/news/articles/c706y4jr95lo

4. Resurgence of preventable diseases threatens children in East Asia and the Pacific. World Health Organization. May 28, 2025. Accessed September 17, 2025. https://www.who.int/westernpacific/news/item/28-05-2025-resurgence-of-preventable-diseases-threatens-children-in-east-asia-and-the-pacific#:~:text=Since%20the%20beginning%20of%202025,January%20to%2010%20May%202025.

5. Ten countries in the Americas report measles outbreaks in 2025. Pan American Health Organization. August 15, 2025. Accessed September 17, 2025. https://www.paho.org/en/news/15-8-2025-ten-countries-americas-report-measles-outbreaks-2025

6. Yousif N. How Canada became the centre of a measles outbreak in North America. BBC. July 20, 2025. Accessed September 17, 2025. https://www.bbc.com/news/articles/c4g8d39gdr0o

7. Nolen S. A debilitating virus surges globally as mosquitoes move with warming climate. The New York Times. August 19, 2025. Accessed September 17, 2025. http://nytimes.com/2025/08/19/health/chikungunya-virus-mosquitoes-what-to-know.html

8. Beatty N, Hamer G, Moreno-Peniche B, et al. Chagas disease, an endemic disease in the United States. Emerging Infectious Diseases. September 2025. doi:10.3201/eid3109.241700

9. Gerlach A. What pharmacists should know as Chagas disease circulates in the US. Pharmacy Times. September 8, 2025. Accessed September 17, 2025. https://www.pharmacytimes.com/view/what-pharmacists-should-know-as-chagas-disease-circulates-in-the-us

10. Kopf M, Carroll L, Thompson A. Outbreaks of rabies seem to be rising across the U.S., CDC surveillance shows. NBC News. August 31, 2025. Accessed September 17, 2025. www.myworkday.com/mjhlifesciences/d/home.htmld

11. Measles vaccination. CDC. January 17, 2025. Accessed September 17, 2025. https://www.cdc.gov/measles/vaccines/index.html?utm

12. Measles (rubeola). CDC. July 15, 2024. Accessed September 17, 2025. https://www.cdc.gov/measles/travel/index.html?utm

13. Chikungunya vaccines. CDC. August 22, 2025. Accessed September 17, 2025. https://www.cdc.gov/chikungunya/vaccines/index.html?utm

14. Valletti D. FDA suspends licensing of Ixchiq Chikungunya vaccine amid safety concerns. Pharmacy Times. August 27, 2025. Accessed September 17, 2025. https://www.pharmacytimes.com/view/fda-suspends-licensing-of-ixchiq-chikungunya-vaccine-amid-safety-concerns

15. Rabies. CDC. April 23, 2025. Accessed September 17, 2025. https://www.cdc.gov/yellow-book/hcp/travel-associated-infections-diseases/rabies.html?utm

16. Yellow fever. CDC. April 23, 2025. Accessed September 17, 2025. https://www.cdc.gov/yellow-book/hcp/travel-associated-infections-diseases/yellow-fever.html?utm

17. Japanese encephalitis. CDC. April 23, 2025. Accessed September 17, 2025. https://www.cdc.gov/yellow-book/hcp/travel-associated-infections-diseases/japanese-encephalitis.html?utm

18. Global typhoid fever vaccination. CDC. May 16, 2024. Accessed September 17, 2025. https://www.cdc.gov/typhoid-fever/php/global-typhoid-fever/index.html?utm

19. Ng K. WHO declares polio outbreak in Papua New Guinea. BBC. May 16, 2025. Accessed September 17, 2025. https://www.bbc.com/news/articles/cvg9men89yvo

20. Grotto I, Agha H, Al-Halaweh, A, et al. Public health, war and cross-border challenges: the recent cVDPV2 polio outbreak in Gaza. eClinicalMedicine. February 27, 2025. doi: 10.1016/j.eclinm.2025.103136.

21. CDC collaborates worldwide to eliminate viral Hepatitis. CDC. July 25, 2025. Accessed September 17, 2025. https://www.cdc.gov/hepatitis/global/what-cdc-is-doing.html