California's whooping cough cases 6 times as high as last year — LA County saw 219% rise

California's cases of whooping cough are more than six times as high as last year, and in Los Angeles County, reports of the highly contagious disease have risen by nearly 220%, according to data from the state Department of Public Health.

The spike reflects a broader trend being seen across the country, with the number of U.S. cases reported by June of this year more than doubling since last year, the Centers for Disease Control and Prevention reports. Public health officials say nationwide cases of the bacterial respiratory illness — which gets its name from the "whoop" sound made when gasping for air during a coughing fit — are returning to pre-pandemic levels. 

"Reported cases of whooping cough were lower than usual over the past few years, since the start of the COVID-19 pandemic," the CDC's National Center for Immunization and Respiratory Disease said in a July 22 statement. "It's likely that preventative actions used during the pandemic (e.g., good hygiene, distancing) lowered transmission of this disease."

Meanwhile, California has seen a rise in cases that far outpaces the increase seen on a national scale, public health data shows.

Rising cases in the state were reported Friday by the Los Angeles Times, with public health data through this summer revealing just how significant the increase has been. Some health experts have said that while cases are returning to numbers seen years ago, not reaching unprecedented new heights, there is still some concern over just how contagious the illness is once it starts spreading.

"It's a big year, no doubt, but I don't think it's dramatically bigger than big years before the pandemic," Mark Sawyer, a professor of pediatrics at UC San Diego, told the health and medicine journal Stat. Still, he added, "it's a very, very contagious infection, so once it gets going, it does spread among susceptible people, and we may have built up a bigger susceptible population than we usually did."  

Early symptoms, including a mild cough, runny nose and low-grade fever, are similar to that of the common cold. But the bacterial illness can progress and become much worse with what the CDC describes as "rapid, violent, and uncontrolled coughing fits," in which patients may struggle to breathe, vomit and even break a rib. Infants face especially high risks of dangerous complications.

Across California, there has been a 605.4% spike in cases since the start of this year through Sept. 30, the latest data available from the state Department of Public Health. It's the highest number of whooping cough infections seen statewide since 2019. 

There have been 1,744 cases reported in California during that time compared to 288 in 2023. 

More than a quarter of the state's cases have been in San Diego, where there were 470 compared to just 85 last year — marking an increase in the county of roughly 553%. In LA County, they went up by 219.9%, from 85 in 2023 to 186 this year.

For cases through the early summer, the jump in California cases was significantly higher than the increase seen nationwide. Between Jan. 1 and June 1, the number of U.S. cases more than doubled from the year before — an increase of about 284.7%. But in California, the number of cases for about the same time span were more than six times as high as last year — a leap of 642.5%.

Still, the number of infections this year is far from the most the state has seen. 

More than 9,000 cases were reported in 2010, the most cases seen in over 60 years in an outbreak that led to the deaths of 10 infants. Four years later, the state reported more than 11,209 cases, with two infants dying from the respiratory illness.

Babies are at especially high risk of suffering dangerous complications from the illness. The CDC reports more than a third of infants younger than 12 months old who get whooping cough need treatment in a hospital.