A virus known for causing a bright red rash on the face is showing up in wastewater systems in more than a dozen Northern California communities, according to new surveillance data.
The data indicate that parvovirus B19 is circulating broadly across the region as flu season winds down.
The virus was found in the wastewater systems of San Francisco, Sacramento, Napa, Sunnyvale, Redwood City, Palo Alto, Vallejo, Davis, San Jose, and the South County Region. Among those, San Francisco, Sacramento, Napa, Davis, Redwood City, and San Jose registered moderate levels of positive samples.
The illness is most common in children, though adults who were never infected as kids can also contract it. It spreads easily from person to person through coughing, sneezing, and saliva, as well as through close physical contact.
In most cases, the infection is mild.
Early symptoms in children can include fever, headache, runny nose, upset stomach and diarrhea. A face rash typically appears as the body begins to fight off the virus, sometimes followed by a second lacy, pink, or purplish rash on the arms, legs, chest, back, and buttocks. That rash can be itchy—especially on the soles of the feet—and may last seven to 10 days, though it can come and go for up to three weeks.
Factors such as sun exposure, temperature changes, stress, and physical activity can make the rash more visible.
Adults tend to experience the illness differently. Rather than a rash, they are more likely to develop painful, swollen, or stiff joints—mostly in the hands, wrists, knees, ankles, and feet—with symptoms typically lasting one to three weeks.
The CDC says most people recover without medical intervention and that the illness generally clears up within seven to 10 days, though symptoms can resurface over several weeks.
Pregnant women, people with weakened immune systems, and those with blood disorders such as sickle cell anemia face the possibility of serious complications. In rare cases, parvovirus B19 infection during pregnancy can cause severe anemia in an unborn child, potentially leading to miscarriage or stillbirth, with the risk appearing highest during the first half of pregnancy.
There is currently no vaccine against parvovirus B19. Public health officials recommend frequent handwashing, covering coughs and sneezes, avoiding contact with sick individuals, and not sharing food or drinks as the best defenses against the virus.
