Whooping cough has swept across Japan, with the number of cases reported so far this year exceeding that of the entire year of 2024.

From the beginning of this year to March 30, the cumulative number of whooping cough patients reported by medical institutions nationwide was 4,771, exceeding 4,054 cases reported in the 12 months of 2024.

With the infectious disease, caused by a type of bacteria called Bordetella pertussis, believed to be spreading mainly among preschool children and elementary and junior high school students, experts have urged people to consider vaccinations.

After the bacteria is transmitted through droplets from coughing or sneezing, patients display cold-like symptoms and then develop severe coughing.

If an infant is infected, symptoms may become severe and life-threatening.

Japan introduced a notifiable disease surveillance system for whooping cough in 2018. The annual total of whooping cough cases exceeded 10,000 in both 2018 and 2019.

Whooping cough infections started to decrease in 2020, when the COVID-19 pandemic broke out, with the annual total of cases falling below 1,000 in 2021 and again in 2022.

The total, however, then began to rise in 2023. In the week until March 30 this year, the number of whooping cough cases came to 578, the highest weekly figure since records started in 2018.

Vaccination is effective for preventing infection.

The combination of five types of vaccines, including one for whooping cough, is routinely offered at public expense and is administered four times between the ages of two months and 18 months.

As the vaccine's effectiveness wanes over time, the Japan Pediatric Society recommends voluntary vaccinations for preschool children and older elementary school students.

Antibiotics are used to treat whooping cough patients, with the bacteria expected to be almost completely eliminated after five days of treatment.

Meanwhile, researchers have called attention to some cases of antibiotic-resistant bacteria strains observed in Osaka and Tottori prefectures.

"While we don't know the connection between the (antibiotic) resistant strains and the spread of the infection yet, the (whooping cough) outbreak may continue," said Motoi Suzuki, director of the Japan Institute for Health Security's infectious disease surveillance center.

"The best preventive measure is getting vaccinated," Suzuki added.