On February 27, 2017, the most recent measles outbreak in Los Angeles County (first announced via LAHAN on December 23, 2016) was declared over. The Interim Health Officer declared an end to the outbreak because at least two 21-day incubation periods (42 days) elapsed from the end of the infectious period of the last known outbreak-related measles case.   

The first identified case transmitted the disease to siblings and a friend which led to a total of 24 confirmed cases (18 in LA County and 6 outside the County) presenting from December 15, 2016 until January 11, 2017. Among the 18 LA County cases, none had documentation of vaccination, though three gave a self-reported history of prior measles vaccination. Fortunately, no patients were hospitalized or died.

A total of 2,219 contacts were followed by the Los Angeles Department of Public Health and affected health care facilities. A total of 177 contacts lacked any vaccinations against measles; 53 of whom received measles post exposure prophylaxis (IgG or a MMR vaccine).

Take Home Points

• Routine vaccination with two doses of measles-containing vaccine is the safest and most effective way to prevent disease. It is routinely recommended for all children and is a requirement for school attendance.
• Consider measles when evaluating any patient who has an acute rash illness with fever.
• Immediately contact your local public health department by phone if you have a suspect measles case. For measles cases in Los Angeles County call: (888) 397-3993. Visit the Los Angeles County Department of Public Health Professional Reporting Page for all reporting resources.

Conclusions

This measles outbreak was suppressed due in part to the prompt recognition and reporting by health care providers in the community and the active contact investigation by public health field staff who encouraged prophylaxis and voluntary isolation for those exposed to a known measles case. The most important factor in suppressing this outbreak was likely the presence of community or “herd” immunity. Thank you to health care providers and staff for immunizing your patients against measles and other vaccine preventable diseases. Your involvement with and general support of outbreak suppression efforts is also very much appreciated.

Additional Resources