June 9, 2011
Measles outbreak over, health officials say
But ongoing measles outbreaks in the world mean vigilance needed
The measles outbreak in Hennepin County is over, state health officials said today. But they cautioned that it's important to remain vigilant in vaccinating for measles and being aware of the signs of measles infection so that further outbreaks don't occur.
The first case of the outbreak was confirmed on March 2, and by late April, 20 cases of measles were identified that were linked to an individual who acquired infection in Kenya in February. During the outbreak, two other cases were identified: one who acquired infection in Florida and one who acquired infection in India.
Health officials said they were willing to call the outbreak over because two incubation periods – periods in which potentially infected people could pass the disease to others – have passed with no new cases reported. People are contagious a few days before and after rash onset. The date of rash onset for the last confirmed case was on April 24.
"Hennepin County Public Health staff need to be applauded for their efforts in finding and working with potentially exposed persons to limit the spread of this disease," said Dr. Ruth Lynfield, state epidemiologist with the Minnesota Department of Health. "We are also grateful to astute clinicians for identifying cases and people in the community for working together to halt this outbreak."
The 23 confirmed cases (ages 4 months to 51 years) were the most reported measles cases in Minnesota since 1991, when 27 confirmed cases occurred. On May 24, U.S. Centers for Disease Control and Prevention reported 118 measles cases, the highest number in the United States for the first 19 weeks of the year since 1996. Measles is circulating in many regions of the world including Asia, Africa and Europe. France in particular is experiencing a large outbreak with approximately 10,000 cases in 2011. Because sustained measles transmission was eliminated in the United States by 2000, cases that occur in the United States are imported or linked to imported cases. Maintaining a high level of two-dose measles vaccine coverage is the key to sustaining measles elimination, Lynfield said.
It is particularly important to ensure 2 doses of MMR vaccine at least 28 days apart in all persons 12 months of age and older who are planning international travel (or other evidence of measles immunity); one dose of MMR can be given to infants 6-11 months prior to travel.
During the outbreak, MDH had recommended an early second MMR dose for Hennepin County residents. Providers have now been advised to resume the routine schedule of providing the second MMR dose at 4-6 years of age.
"We can't be certain where the next measles case will come from. Being vaccinated for measles is your best protection and keeping immunization rates high for everyone is the best way to protect our communities," Lynfield said.
For more information on measles, visit www.health.state.mn.us/divs/idepc/diseases/measles/basics.html.
Dr. Ruth Lynfield