Each year, travelers face a changing landscape of health risks. In 2026, global travel, migration, and environmental changes continue to create new opportunities for infectious diseases to spread. Mosquito-borne illnesses are increasing in many regions. Meanwhile, vaccine-preventable diseases, once controlled, are returning in some parts of the world. Understanding these risks is essential for anyone preparing international travel plans.

Among the most significant concerns is dengue fever. Annually, up to 400 million people are infected with dengue worldwide. Of those infected, approximately one-quarter develop symptoms. Cases continue to rise across many regions. Dengue remains one of the most common mosquito-borne illnesses affecting travelers today.

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In surprising findings, recent research has linked vaccines to lower dementia risk. Another recent study may help explain why this connection exists. Researchers found that severe infections may increase dementia risk years later. The findings suggest that preventing infections could help protect brain health.

The study included more than 62,000 older adults. Researchers recruited participants in 2016 and followed them through 2021. Participants were at least 65 years old when the study began. The average participant age was approximately 81 years old.

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In recent years, mosquito populations have expanded into traditionally cooler regions. Previously, many disease-carrying mosquitoes were concentrated in warmer climates. As global temperatures rise, however, some mosquito species are adapting to new environments and spreading farther north.

This shift has increased concerns about mosquito-borne illnesses in areas that historically faced fewer risks. As a result, researchers are searching for better ways to track mosquito populations and understand how they move.

A new study published in the journal PNAS Nexus explores one possible solution: harmonic radar tags.

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Malaria remains a devastating disease with major global impact. In 2024, 282 million malaria cases caused over 600,000 deaths. The World Health Organization reported cases across 80 countries. Africa carried 95% of both cases and deaths.

About 75% of malaria cases occurred in children under five. This burden shows how deeply the disease affects vulnerable populations. A new discovery offers hope against this global health crisis.

Researchers identified a protein that helps malaria parasites reproduce. When scientists deactivate this protein, parasite growth drops sharply. This finding could help reduce transmission and lower infection rates.

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Travel can expose people to many valuable new experiences. It offers chances to see new sights, taste new foods, and meet new people. These opportunities may not exist in the same way at home.

However, travel can also expose people to new health risks. Many people in the United States view polio as a past disease. Yet, in some countries, polio transmission still occurs.

Recent reports show the polio virus appearing in several regions worldwide. Some common travel destinations, including the United Kingdom and Germany, now carry risk. In March 2026, the Centers for Disease Control and Prevention issued a level 2 travel notice.

A level 2 notice advises travelers to take extra precautions. It does not suggest canceling or avoiding nonessential travel. Polio continues to circulate across parts of Africa, the Middle East, and Europe.

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Sometimes important answers appear in unexpected and surprising places. People often find lost items hidden under cushions or inside drawers. Researchers discovered a similar surprise while studying vitamin D and COVID-19.

Scientists found regular vitamin D intake may reduce Long COVID risk. This finding came from researchers at Mass General Brigham. Their results were published in the Journal of Nutrition.

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When removing contamination, accidents can happen if people are not careful. For example, while dusting an antique bowl, someone might knock over a lamp. The lamp could fall and shatter into pieces.

A similar process can occur in the immune system. When the body responds to infection, mistakes sometimes occur. These errors can trigger cascading negative health effects.

Researchers from University of California, San Francisco recently investigated a link between Epstein–Barr virus (EBV) and Multiple sclerosis (MS). This finding is important because EBV is extremely common. About 96 percent of people become infected during their lifetime. Most infections occur during childhood and cause few symptoms.

In some cases, EBV causes infectious mononucleosis, often called “kissing disease.” MS is a chronic autoimmune disease of the central nervous system. In MS, the immune system attacks myelin surrounding nerve fibers. Myelin is a fatty, protein-rich layer that protects nerve signals. Nearly one million Americans currently live with MS.

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False convictions in criminal cases can cause serious harm. Similar damage can occur when false narratives spread about disease origins. Conspiracy theories, misinformation, and distrust of medicine often follow these claims. A recent study examining viral evolution offers new insight into how many pandemic viruses emerge.

The research focused on pandemic viruses. Specifically, it examined how they acquire their ability to infect humans. This can occur naturally or through laboratory manipulation. Many pandemic viruses are zoonotic. These viruses originate in animals before spreading to people. Some public claims argue that certain viruses gained their human infectivity through laboratory work. However, the study’s findings challenge that idea for most major outbreaks.

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Typhoid fever is an old bacterial illness that still threatens global health. Many people in developed nations assume the disease disappeared long ago. Yet this belief is mistaken because the bacterium never vanished worldwide. Instead, the disease remains common in many developing nations today.

Typhoid fever is caused by the bacterium Salmonella enterica serovar Typhi. The bacterium spreads through contaminated food or drinking water. Poor sanitation and unsafe water systems allow the infection to circulate widely. As a result, many regions still experience frequent outbreaks of the disease.

Researchers warn that typhoid fever is becoming more difficult to treat. A 2022 study published in The Lancet revealed troubling new trends. Scientists found that many S. Typhi strains are gaining resistance to antibiotics. This discovery raises concern because antibiotics remain the only effective treatment.

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COVID-19 infection during pregnancy has raised concerns since the start of the pandemic. Earlier research showed that the virus could increase the risk of complications such as stillbirth, premature birth, and preeclampsia. Preeclampsia is a dangerous blood pressure disorder that threatens both the pregnant person and the developing fetus.

A recent international study suggests that COVID-19 vaccination may help reduce this risk. Researchers found that coronavirus infection increased the likelihood of preeclampsia by about 45 percent among pregnant participants compared with those who were not infected. The increase was even greater among people who were unvaccinated when they became infected. In that group, the risk rose by roughly 78 percent.

Vaccination appeared to offer meaningful protection. Participants who received the primary COVID-19 vaccination and stayed up to date with booster doses had a 33 percent lower risk of developing preeclampsia. The protective effect was even stronger among those with existing health conditions. Pregnant participants with illnesses such as diabetes or heart disease who received a booster saw their risk fall by about 58 percent.

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