Parvovirus B19 Detected in San Jose Wastewater

WastewaterSCAN data for San Jose on May 14 showed human parvovirus B19 at a medium level at the San Jose-Santa Clara Regional Wastewater Facility, with 9 of the previous 10 samples testing positive. The dashboard covers a plant serving about 1.5 million people in Santa Clara County and lists no short-term trend change over the prior 21 days. Santa Clara County Public Health describes wastewater as an early signal that can show when infections are rising or when new diseases are appearing in the community. (data.wastewaterscan.org) CDC says parvovirus B19 is a respiratory virus that usually causes mild illness but can lead to severe outcomes in some groups. (publichealth.santaclaracounty.gov) ### What exactly was detected in San Jose’s wastewater? The WastewaterSCAN dashboard on May 14 listed “Parvovirus” at a medium level for San Jose and said 9 out of 10 samples in the 10 days before the latest sample date were positive. (publichealth.santaclaracounty.gov) The plant named on the dashboard is the San Jose-Santa Clara Regional Wastewater Facility. Santa Clara County Public Health says higher concentrations of genomic material in wastewater generally mean more people may be infected in the community. The county says wastewater results arrive sooner than many case results, which is why officials use them as an early warning signal. ### Is this the same “parvo” that affects dogs? (data.wastewaterscan.org) CDC says parvovirus B19 infects humans and is different from the canine parvovirus that affects dogs. In people, the virus most commonly causes fifth disease, a mild rash illness that usually affects children. CDC says parvovirus B19 spreads mainly through respiratory secretions from an infected person, including by coughing or sneezing. The agency says people can also spread it before they develop the characteristic rash. (data.wastewaterscan.org) ### Who faces the biggest health risk from parvovirus B19? CDC said in a June 2025 MMWR report that pregnant women, immunocompromised people and people with chronic hemolytic blood disorders face the highest risk for severe outcomes. The agency said infection can cause adverse fetal outcomes in pregnancy and severe anemia in some patients with blood disorders or weakened immune systems. (publichealth.santaclaracounty.gov) CDC’s pregnancy guidance says infection early in pregnancy can slightly increase the risk of miscarriage and can cause blood, heart or liver problems in a fetus. The agency advises pregnant people to contact a healthcare provider if they have symptoms or know they were exposed. (cdc.gov) ### What symptoms do people usually get? CDC says many infections are mild or asymptomatic. In children, the best-known sign is a bright facial rash often called “slapped cheek,” while adults may have joint pain that can last for weeks or longer. (cdc.gov) Mayo Clinic says people who are pregnant, immunocompromised or have blood conditions may need medical attention if infected. CDC says no antiviral medication exists to treat parvovirus B19 infection. (cdc.gov) ### What are health officials telling people to do now? CDC says there is no vaccine to prevent parvovirus B19 infection and recommends using core respiratory-virus precautions. Those measures include covering coughs and sneezes, cleaning hands often and seeking medical advice if you are pregnant or have an underlying blood disorder or weakened immune system. (cdc.gov) Santa Clara County Public Health says wastewater data helps guide outreach and helps hospitals prepare for surges. The county’s wastewater program tracks data from four treatment plants in Gilroy, Palo Alto, San Jose and Sunnyvale. (cdc.gov) ### Where can residents watch for updated local data? WastewaterSCAN’s public dashboard lists current readings for San Jose, Palo Alto, Sunnyvale and Gilroy, including parvovirus alongside measles, influenza, RSV and norovirus. (mayoclinic.org) The San Jose entry on May 14 continued to show a medium parvovirus level. Santa Clara County’s public health website links residents to the county wastewater program and the WastewaterSCAN dashboard for updated monitoring data. (cdc.gov) CDC’s June 2025 report said parvovirus B19 activity in the United States had remained elevated after rising in 2024, giving clinicians a reason to watch for cases in higher-risk groups. (data.wastewaterscan.org) (publichealth.santaclaracounty.gov)