Epidemiology & Assessment

Ebola Virus Disease

August 18, 2014
West Africa has been experiencing a large outbreak of Ebola Virus Disease (EVD) since December of 2013. The nations of Guinea, Sierra Leone, Liberia and most recently Nigeria remain the primary areas affected. The number of cases continues to increase, and as of August 15, 2014, there were 2127 confirmed or suspect cases including 1145 suspected case deaths reported in the four affected West African nations. There are no suspect or confirmed cases of Ebola in the United States, aside from two U.S. citizens who were transported to Emory University for further care after contracting the disease while caring for patients with EVD in Liberia. The risk of Ebola to the U.S. or Orange County is small. For the latest updates on Ebola activity, please visit: http://www.cdc.gov/vhf/ebola/index.html. For health care provider information, click here.

Pertussis Activity Continues at Epidemic Levels in Orange County and StatewideAugust 18, 2014
As of August 16, 2014, 250 pertussis cases have been reported in Orange County, compared with 43 cases at this time last year. Pertussis peaks in incidence every 3-5 years as the number of susceptible people in the population increases; the last epidemic in California was in 2010. For more information, click here.

Increase in West Nile Virus Cases

August 5, 2014
Orange County has seen an increase in West Nile Virus cases in the last month. Residents are encouraged to take measures to prevent mosquito bites, including:

  • Using DEET-containing insect repellant
  • Wearing long-sleeve shirts and pants as weather permits
  • Avoiding being outside from dusk to dawn



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.

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