Epidemiology & Assessment

The Epidemiology and Assessment unit’s medical directors, public health nurses, and epidemiologists investigate individual cases and outbreaks of reported communicable disease (see List of Reportable Diseases) per the State of California Code of Regulations. We monitor disease trends, and often provide current statistics and other information to doctors, hospitals, the public and news media. For more information or CD reporting 24/7 call 714-834-8180.

For questions or comments, please email epi@ochca.com.

Latest News & Health Advisories

Provider Adivsory: Two New Mumps Cases Indentified in Orange CountySeptember 22, 2017
Two new cases of mumps have been identified in Orange County residents in the past ten days. The two cases are adults in their twenties and have no identified common contacts. Neither has a history of travel or contact with other mumps cases. They had symptom onset dates of September 6 and September 9.
Orange County has had 24 cases of mumps reported this year. This includes 13 cases associated with the Chapman University outbreak which ended in April, and five additional cases who have no history of travel and apparently acquired infection locally.

Provider Advisory: Update Hepatitis A Outbreaks in HomelessSeptember 21, 2017
Outbreaks of Hepatitis A virus (HAV) infection have been identified in homeless and illicit drug user populations in San Diego, Santa Cruz, and Los Angeles Counties. San Diego County has identified 444 cases of HAV infection, including 16 deaths, since early in 2017; Santa Cruz County has had 69 cases since April. Earlier this week, the Los Angeles County Department of Public Health reported an outbreak of HAV infections in their homeless population. Two Los Angeles cases apparently acquired disease in that county; eight more have occurred there after exposure in San Diego or Santa Cruz.

Hepatitis A Outbreaks in Homeless and Illicit Drug User Populations in CaliforniaSeptember 20, 2017
San Diego, Santa Cruz, and Los Angeles Counties are experiencing Hepatitis A outbreaks primarily in their homeless and illicit drug user populations. San Diego County has had 444 cases of Hepatitis A, Santa Cruz County has reported 69, and Los Angeles County has reported 10 cases.

Influenza Activity Has Increased in Orange County Including an Influenza-Associated Death Under 65 Years of AgeAugust 30, 2017
Orange County Health Care Agency (HCA) has received an unusual volume of influenza reports for this time in the summer. Most notably, a large increase in influenza cases was reported during week 33 (week ending 8/19/2017). Seasonal influenza A/H3, A/(H1N1)pdm2009, and B viruses are still in co-circulation throughout the community. An influenza-associated death was also reported in a 50 year old male who had significant underlying medical conditions.

Reports of West Nile Virus Infections are Increasing in Orange CountyAugust 18, 2017
Five cases of West Nile Virus (WNV) infection have been identified in Orange County this year, including four new cases reported to the Orange County Health Care Agency (OCHCA) in the past week. Three of these four are WNV neuroinvasive disease. According to the Orange County Mosquito and Vector Control District, the highest concentrations of WNV-positive mosquitoes has been found in La Habra, Anaheim, and Fullerton. For California, 41 cases of WNV infection from nine counties have been reported so far this year.