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During the winter of 2024-2025, cases of a highly contagious stomach bug characterized by sudden vomiting and diarrhea surged. Nicknamed the "Ferrari of viruses" for its rapid spread, norovirus is also known for its ability to quickly infect cruise ships.
The U.S. Centers for Disease Control and Prevention (CDC) cruise ship inspections for illness are on pace to set new records in 2025.
As of July 2025, the CDC's Vessel Sanitation Program had reported 18 gastrointestinal illnesses on cruise ships this year, most classified as norovirus.
A University of Surrey–led research team identified cruise ship dining areas as priorities for preventing norovirus outbreaks.
However, according to those who study it, the virus hasn't received the attention it deserves, wrote Kate Schweitzer in an article published by JAMA on July 25, 2025.
From a prevention perspective, scientists have taken several approaches to developing a norovirus vaccine. Unfortunately, no candidate vaccine has been approved yet.
Schweitzer's unedited article is posted at this JAMA link.
Since Lyme disease was initially confirmed in Connecticut decades ago, it has become one of the most widespread vector-borne illnesses in the world, including the United States.
Over the years, this long-lasting disease has impacted countless outdoor-loving adventurers from the northeast, and it is now also found in the Midwest, in states such as Michigan.
To help identify at-risk areas, the U.S. Centers for Disease Control and Prevention (CDC) published the Tick Bite Data Tracker. As of July 25, 2025, this digital app displays case data from emergency room visits.
While cases have peaked in May each year, Lyme disease cases continue to be reported until winter.
To enhance the diagnosing of Lyme disease infection, a recent episode of the Mayo Clinic's Tomorrow's Cure explores how researchers are advancing diagnostic tools to detect Lyme disease.
The episode features two leading experts, at Massachusetts General Hospital, and Harvard Medical School. They discuss the latest advancements and the ongoing efforts to control Lyme disease better.
From a prevention perspective, the CDC advises avoiding tick bites while Lyme disease vaccine candidates complete clinic trials.
Since the beginning of 2025, three European countries have reported human cases of West Nile virus infections: Greece, Romania, and Italy.
According to Italy's National Institute of Health, 10 confirmed human cases of West Nile virus have been reported since the beginning of 2025.
As of July 20, 2025, seven of these mosquito-transmitted cases had been reported from the Lazio region, specifically from Latina, Italy's second most populous region, with over 5 million residents.
Throughout 2024, twenty WNV-related deaths were recorded in Italy.
In the United States, 1,466 WVN cases were reported in 2024, with over 1,000 cases involving the nervous system. Most WNV cases are reported in the southwest states.
As of July 24, 2025, WNV vaccine candidates continue to be tested in clinical research for prevention purposes. However, none have been approved for use in humans.
In conjunction with the Regional Health Agencies (ARS) and mosquito control operators, Public Health France recently updated that indigenous (local) transmissions of the Chikungunya virus have been identified in mainland France.
As of July 22, 2025, 38 Chikungunya cases have been confirmed in the Provence-Alpes-Côte d'Azur, Corsica, Occitanie, and Auvergne-Rhône-Alpes regions, which were already affected in previous years, and for the first time in the Grand Est and Nouvelle-Aquitaine regions.
Public Health France reiterates that the number of transmission hotspots illustrates the significant risk of indigenous transmission of these viruses in mainland France. Additional cases are likely to be identified, including those outside the usual transmission areas.
Additionally, since May 1, 2025, 833 imported cases of Chikungunya have been confirmed; many of these travelers had visited the French departments of Réunion and Mayotte.
Currently, the U.S. CDC's Level 2 - Practice Enhanced Precautions, Chikungunya Travel Health Advisory does not include southern France. However, the CDC recommends vaccination for many travelers before visiting areas with Chikungunya outbreaks.
According to recent research, preventing Chikungunya infections is essential.
Published in the Journal of Infectious Diseases on June 16, 2025, this study provides the first evidence that the chikungunya virus directly infects chondrocytes, the cells responsible for producing cartilage and may contribute to chronic musculoskeletal diseases by affecting the function of cartilage cells.
In the United States, as in Europe, two Chikungunya vaccines have been approved and are commercially available.
The ARS Auvergne-Rhône-Alpes states that most dengue cases reported in mainland France involve international travelers who were infected with the mosquito-transmitted virus while visiting a tropical region.
If people return to France infected, dengue symptoms occur on average within 4 to 7 days after the infective bite. These are considered imported cases.
However, recent reports suggest that a local outbreak may occur in July 2025.
Approximately 50 kilometers southwest of Lyon, France, Saint-Chamond, in the Auvergne-Rhône-Alpes region, has confirmed a second locally acquired case of Dengue as of July 15, 2025.
'At this stage, it is not possible to establish a link with the first indigenous case identified in Saint-Chamond, as the investigations are still ongoing,' wrote ARS Auvergne-Rhône-Alpes.
An entomological survey conducted on July 18, 2025, confirmed the presence of tiger mosquitoes in areas frequented by the infected person and informed residents of an adulticide treatment. These mosquitoes carry dengue viruses.
Around one hundred homes in the affected area have been informed.
As of July 23, 2025, Sante Publique France reported a total of four locally acquired cases of Dengue for 2025.
In 2024, France reported 82 locally transmitted cases of dengue fever. Outbreaks were identified in the Provence-Alpes-Côte d'Azur, Occitanie, and Auvergne-Rhône-Alpes regions.
The World Health Organization has classified Dengue as a grade 3 emergency, with an estimated 4 billion people at risk in approximately 110 countries, including areas within the United States, such as Florida and Puerto Rico.
While numerous countries offer Dengue vaccinations, only Puerto Rico continues to provide a first-generation vaccine to children.
Note: This article was updated on July 24, 2025.
The South Carolina Department of Public Health (DPH) recently confirmed that a cat and a fox have tested positive for rabies in separate incidents that impacted people.
As of July 17, 2025, rabies is most commonly found in South Carolina (S.C.) wildlife, including raccoons, skunks, foxes, and bats.
However, most rabies cases in the United States are associated with bat bites, not dog bites.
In Greenville County, the cat that tested positive for rabies was found near Holland Ford and Beech Springs roads in Pelzer, S.C.
In 2024, six of the 81 confirmed rabies cases in S.C. were in Greenville County, which has a population exceeding 500,000.
In Marion County, the fox that tested positive for rabies was found near the intersection of Sandhill and Ellis roads in Marion. One person was exposed and has been referred to their healthcare provider. This fox is the third animal to test positive for rabies in that county in 2025.
There have been 45 cases of rabid animals in S.C. in 2025.
Since 2002, S.C. has averaged approximately 144 positive cases a year.
Terri McCollister, DPH, Rabies Program manager, commented in a press release, “Any mammal can carry and transmit the rabies virus to people or pets. Therefore, give wild and stray animals plenty of space.”
According to the DPH, rabies is a treatable and vaccine-preventable disease. Rabies information for local Public Health offices is available at dph.sc.gov/RabiesContacts. For more information on rabies, visit dph.sc.gov/rabies or cdc.gov/rabies.
