Epidemiology & Assessment

Mosquitos capable of transmitting chikungunya and dengue fever found in Mission ViejoOctober 19, 2015
The Orange County Mosquito and Vector Control District (OCMVCD) is working to eradicate invasive Aedes Aegypti mosquitos in the Mission Viejo neighborhood where they were identified. The District is conducting neighborhood inspections and treating areas of concern. These mosquitos can act as a vector to spread several viruses including chikungunya, dengue, and yellow fever. There have been no locally-acquired cases of these viruses, but travelers who acquire one of these infections could serve as a source of transmission if bitten by an Aedes Aegypti mosquito.

Human Cases of West Nile Virus (WNV) continue to be reported in Orange CountySeptember 25, 2015
Orange County has reported its first WNV-associated fatality this season, a resident of Buena Park in their 80’s with underlying medical conditions. So far this year, 26 human cases of WNV have been reported in Orange County, and California has a total of 201 human cases, including 10 WNV-related fatalities.

Official start of the influenza season is less than two weeks awaySeptember 25, 2015
Flu activity is low across the U.S. now, but usually begins to increase in October. Providers are encouraged to begin vaccination efforts as soon as vaccine is available.


Certain communicable diseases are required to be reported to the local health department (see List of Reportable Diseases) as per the State of California Code of Regulations. Epidemiology and Assessment (E&A) unit's medical directors, public health nurses, and epidemiologists investigate individual cases and outbreaks of reported communicable diseases. We monitor disease trends, and often provide current statistics and other information to doctors, hospitals, the public and news media. We may also provide education or preventive treatment in some circumstances. Although other units handle reports of HIV/AIDS, tuberculosis (TB) or sexually transmitted diseases (STDs), we do monitor their trends in Orange County. For more information or to report a Public Health emergency 24/7 call 714-834-8180.

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