An aerial view shows the skyline of San Francisco on May 19, 2026.

Rates of rotavirus, a highly contagious illness that can cause severe stomach flu symptoms among small children and leads to infant hospitalization, are still high or spiking in several California cities. But health experts say change may soon be on the horizon. 

According to WastewaterSCAN, which monitors multiple different viruses in municipal wastewater, traces of rotavirus are either high or spiking in San Francisco, Fremont, San Jose, Santa Cruz, Gilroy, Marina, Ontario and Los Angeles County. However, Dr. Matthew Willis, a former health officer for Marin County, said that it’s unlikely that the illness will surge into summer based on historic seasonal trends. 

Article continues below this ad

“I’m not overly concerned at this stage that we’re going to have a rough summer,” Willis told SFGATE on Tuesday, adding that rotavirus typically peaks later than winter viruses like RSV and the flu. Currently, the wave appears to be subsiding in........

© SFGate