Coronavirus Breaking News

A multijurisdictional measles outbreak has occurred in Canada, beginning in New Brunswick in October 2024. This year, it has spread in Ontario (1,949), and related cases have been reported in Alberta, British Columbia, Manitoba, the Northwest Territories, Nova Scotia, Prince Edward Island, Quebec, and Saskatchewan.

Canada Health's Measles and Rubella Weekly Monitoring Report states that, of the 2,755 measles cases (2,429 confirmed, 326 probable) reported in 2025, 1,867 cases are linked to this outbreak as of June 2, 2025.

At the end of May 2025, only 244 new measles cases were reported in one week, indicating a continued decline of this outbreak.

The government says, 'If you're infected with the measles virus, you can spread it to others. This is possible from 4 days before the onset of the rash to 4 days after the rash begins. Isolate at home and call a health care provider immediately. They will advise you on what to do.'

As of June 8, 2025, measles vaccination services are offered throughout Canada.

According to a Case Report published by the Journal of Infection and Chemotherapy (Volume 31) in June 2025, Japanese encephalitis (JE) has emerged in a previously non-reported area in Japan, suggesting that the number of JE patients may be underestimated in Japan.

This report describes three cases of JE in a single hospital in Narita over three years.

These researchers suggest that physicians in Japan should consider JE as a differential diagnosis in 2025 when encountering cases of encephalitis or meningitis with unknown etiology during the warm season, even in areas where JE has not been previously reported.

This prefecture is located a few miles east of Tokyo, a city with over 35 million residents.

JE is an infection of the brain caused by the Japanese encephalitis virus, which is spread to people through the bite of an infected mosquito or close contact with livestock, such as birds, goats, and pigs.

In Japan, JE used to be endemic, and more than 1000 JE patients had been reported before the 1960s.

However, the introduction of the JE vaccine in 1954 and its widespread use in childhood vaccination from 1967 dramatically reduced the disease burden. As of 2022, only one case had been reported in Chiba and Ibaraki prefectures, respectively, in the past 10 years, and both cases occurred in areas famous for pig farming, far from Narita City.

As of June 5, 2025, the U.S. CDC recommends JE vaccination for specific people visiting Japan.

The CDC recommends vaccination for travelers who are moving to an area with JE, spend long periods in areas with JE present, or frequently travel to those areas in Japan.

JE vaccination is not recommended for travelers planning short-term trips to urban areas or those traveling to places with no clear JE season. 

When departing for Japan or any other JE outbreak area, such as Australia, Valneva SE's IXIARO® (JESPECT®) vaccine is commercially offered at travel clinics and pharmacies in 2025.

Since late May 2025, France's overseas department of Mayotte has experienced a significant outbreak of the mosquito-transmitted Chikungunya virus throughout the island. 

As of June 2, 2025, Public Health France reports a total of 560 confirmed cases of chikungunya recorded during this phase of the ORSEC arbovirus plan.

From a location perspective, there has been a persistent concentration of cases in the municipalities of Mamoudzou, Pamandzi, and Dzaoudzi.

These are Mayotte's first locally transmitted cases of chikungunya since the 2005–2006 outbreak, which resulted in approximately 7,300 cases. 

According to the World Health Organization (WHO), Chikungunya outbreaks have been documented on islands within and countries bordering the Indian and Pacific Oceans, such as Mauritius, Réunion, Somalia, and Sri Lanka, in 2025.

Public health response measures have included targeted vaccination efforts with Valneva SE's IXCHIQ® vaccine, the first approved monovalent, single-dose, live-attenuated vaccine.

While the WHO states that no measures related to international traffic and trade are warranted at this time, the U.S. CDC has updated its information to a Level 2 - Practice Enhanced Precautions, Travel Health Advisory.

The CDC recommends vaccination for travelers visiting an area with a chikungunya outbreak. Furthermore, if you are pregnant, consider reconsidering travel to the affected areas, particularly if you are nearing the delivery of your baby. Mothers infected around the time of delivery can pass the virus to their baby before or during delivery. 

In addition to chikungunya, another mosquito-transmitted disease has been spreading on Mayotte. The circulation of dengue fever on the island has reached 21 confirmed cases since the beginning of 2025.

Before visiting Mayotte in June 2025, the CDC recommends consulting with a travel vaccine specialist to discuss immunization options.

With measles cases being reported in many countries this year, the U.S. Centers for Disease Control and Prevention (CDC) issued a Travel Health Advisory highlighting updated vaccination guidance regarding this highly contagious respiratory illness.

As of May 28, 2025, the CDC states that international travelers are at risk of contracting measles if they have not been fully vaccinated at least two weeks before departure or have not had measles in the past.

Therefore, the CDC recommends that 'all international travelers should be fully vaccinated against measles with the measles-mumps-rubella (MMR) vaccine, according to the CDC's measles vaccination recommendations for international travel. 

This is essential guidance since most people who bring measles into the United States are unvaccinated U.S. residents who get infected during international travel.

Currently, significant measles outbreaks have been confirmed in the Region of the Americas, including Canada (2,755 cases), Mexico, and Texas.

While the Texas measles outbreak has significantly slowed, the outbreak in Ottawa, Canada, continues to expand, with 1,949 cases reported.

As of June 4, 2025, various measles-containing vaccines are available at health clinics and pharmacies in the United States.

The Colorado Department of Public Health (CDPH) and Environment, along with El Paso County Public Health, have recently confirmed six measles cases that passed through Denver International Airport, which set an all-time passenger record in 2024, serving 82,358,744 passengers.

In May 2025, measles was confirmed in two unvaccinated residents of El Paso County. These adults are unrelated, but were at Denver around the same time on May 14, 2025.

Both individuals are recovering at home.

In addition, a third Colorado passenger on Turkish Airlines who arrived in Denver on May 13, 2025, has been confirmed positive for measles. The vaccinated adult from Arapahoe County is recovering at home. No public exposures have been identified in connection with this case.

According to a CDPH press release on June 1, 2025, this brings the total number of cases associated with an out-of-state traveler who flew while infectious to six: four passengers on the flight (three Colorado residents and one out-of-state resident) and two El Paso County residents who were at the airport during the exposure period.

Separately, the U.S. CDC published a Global Measles Outbreak Travel Health Advisory on May 28, 2025.

Measles is highly contagious and can sometimes lead to serious health problems, but it is a vaccine-preventable disease. The measles, mumps, and rubella (MMR) vaccine provides strong protection and is generally available at health clinics and pharmacies in the U.S.

After six years without reporting a Zika virus case, the Hawaiʻi Department of Health (DOH) is investigating travel-related cases involving two individuals.

On May 27, 2025, the DOH announced that vector control teams are responding and will continue operations in areas where individuals have spent time, including the Waialua/Haleʻiwa area on the island of Oʻahu.

While Hawaiʻi has mosquito species capable of transmitting Zika, but the virus is not established in the state. As of June 2025, no locally acquired cases have been documented in Hawaiʻi.

The most recent travel-related Zika case in Hawaiʻi was reported in 2019. Travel-associated cases were more frequently reported in Hawai‘i during 2015-2019 when Zika was circulating globally, peaking at 25 cases in 2017.

Over the last few years, there has been a significant increase in Zika cases reported in the Americas, including in Puerto Rico. During 2025, over 12,600 cases have already been reported.

The DOH says Zika can also be transmitted through sex from a person who has Zika. The virus has been found in semen, vaginal fluids, saliva, urine and breast milk.

While most people recover from this mosquito-transmitted disease, pregnant women and their unborn children may become infected, leading to serious health issues. 

A study published in January 2025 found that the mortality rates among 11.4 million children born with a severe Zika virus infection were higher. Young children with congenital Zika syndrome (CZS) had a 13-fold higher risk of death compared with those without CZS.

This study found a cause-specific mortality hazard ratio of 30.28.

As of June 2, 2025, the U.S. Food and Drug Administration has not approved a vaccine that prevents Zika.

The U.S. CDC says, regardless of where you live or visit, if mosquitoes are active in your area, wear long clothing and use insect repellent to reduce the risk of bites. Additionally, travelers returning from an area with a risk of Zika should take steps to prevent mosquito bites for three weeks after their return.

Through the initial five months of 2025, Zika virus (ZIKV) outbreaks continue as a significant, measurable public health concern worldwide.

In the Region of the Americas, over 12,600 Zika patients have been identified as of June 1, 2025.

Last year, 42,127 ZIka cases and two related fatalities were reported in the Americas in 2024, led by Argentina, Brazil, Bolivia, Colombia.

Foremost among public health leaders' focus is when a pregnant woman becomes infected with this mosquito-transmitted virus. While pregnant, ZIKV can induce severe defects of the fetal brain and, eventually, microcephaly in the infant.

To better understand this health risk, an Ohio State University (OSU) study published in the Proceedings of the National Academy of Sciences on May 23, 2025, reveals the biological secret to the Zika virus's infectious success.

These researchers found that Zika utilizes the host cells' own "self-care" system to clear away useless molecules, thereby suppressing the host proteins that the virus has employed to enter those cells in the first place. 

They wrote in a press release on May 27, 2025, 'While these cell surface proteins are valuable for viral entry, they also have roles in producing an antiviral response. Before that can happen, the virus manipulates a process cells use to keep themselves healthy to lower the proteins' activity, clearing the way for unfettered viral infection.'

'Though other viruses, such as HIV, are known to silence host receptors that let them into cells, Zika is unusual for having at least three of its proteins that can get the job done,' said Shan-Lu Liu, senior author the study and a virology professor in the Department of Veterinary Biosciences at OSU.

"That's the most interesting part: It's amazing that not only one, but several Zika proteins can do this."

"We looked at two Zika virus strains and examined three physiologically relevant cell types. With both strains, we observed downregulation in all three cell types. It looks like this is an important mechanism," added Liu.

Although further research is needed to confirm this, there is a possibility that this mechanism is relevant to the Ebola virus, which utilizes the TIM-1 protein to access host cells, or to other pathogens in the same flavivirus family, including Zika, West Nile, yellow fever, and dengue viruses. 

"The bottom line is this speaks to the co-evolution of viral-host interactions. The more important a host factor is to a virus, the more a virus is going to do to take control of it," Liu said. "Understanding these mechanisms is an important part of being prepared for emerging or reemerging viruses that cause infectious diseases."

As of June 2025, there are no Zika preventive vaccines available, and the U.S. CDC recommends pregnant women avoid visiting areas reporting Zika outbreaks.

Over the last few years, Zika cases have been reported in Puerto Rico, Costa Rica, and other tourist favorite destinations.