LINCOLN, Neb. - An outbreak of rubella among residents of three states in the Midwest has resulted in nearly 120 cases.
At least 116 rubella cases have been identified since late March: 82 in Nebraska, 29 in Iowa and five in Minnesota.
Most cases involve foreign-born meat packing workers, most likely because most Central and South American countries do not immunize against rubella, so people born in these areas are susceptible to infection.
Mexico has reported an ongoing rubella outbreak for the past two years, with approximately 40,000 cases last year and 10,000 so far this year. Mexico began vaccinating infants and children last year, but this does little to protect adults. In addition, the close quarters of meat packing plants allow the airborne disease to spread from person to person.
Rubella can have devastating consequences for pregnant women. These include an increased risk of children being born with congenital rubella syndrome, which can lead to deafness, blindness, congenital heart defects and mental retardation, or fetal death.
Symptoms of rubella include rash, swollen glands in the neck or behind the ears and pain in fingers, knees and other joints. Symptoms may be mild enough to escape notice in some cases. As a result, many people may continue to work and spread the illness to others. As many as 50% of infections are asymptomatic.
Lack of immunity, coupled with tight living quarters and the mobility of the population allowed rubella to spread very quickly among the Hispanic population in Nebraska, said Richard Raymond, MD, of the Nebraska Health and Human Services System.
In addition, two smaller outbreaks have occurred in day care centers. Sixteen of Nebraska's 82 cases were in children younger than 4 years.
"They had no contact with the food processing industry that we've been able to epidemiologically identify," Raymond said. "It was a red flag to all of Nebraska that when (rubella) hits one population, it can spread to the unimmunized. These were very young kids who had not yet received a dose of MMR (measles, mumps, rubella vaccine, M-M-R II, Merck & Co.)."
Four pregnant women became ill with rubella. Raymond said there may be more cases involving people who did not seek treatment. "We're really worried in the next few months that we might see some congenital rubella cases in newborn infants. We're not out of the woods on that by any stretch of the imagination."
In Iowa, "about 60% of cases have been directly linked to the packing plants," said Pam Lutz, chief of the bureau of immunization with the Iowa Department of Public Health. Ages of identified cases range from 15 months to 39 years. The majority of those infected have been Hispanic, foreign-born people.
However, none of the cases in Minnesota seem to be related to meat packing. "What we're discovering is that this is more of an ongoing issue as opposed to a true outbreak," said Kristen Ehresmann, RN, MPH, Minnesota Department of Health. "Our feeling is that although the Nebraska and Iowa outbreaks really brought this to our attention, this is really something that's been ongoing and hasn't been picked up by our traditional systems, partly because of the population it's affecting, and because of their access to medical care."
Cases have been reported in Minneapolis as well as in rural communities. Both children and adults have been infected.
Thanks to an extensive immunization program implemented in Nebraska, no new rubella cases have been reported there for a few weeks. "We went into every food processing plant in Nebraska that would let us and did mass immunizations," Raymond said.
Immunization clinics were held at Catholic churches and county clinics, and the state's Native American and Chicano center offered free immunizations five days a week for several weeks "to try to make access as easy as we could. I think it definitely has helped. The problem now is the mobile population. We have a lot of migrant workers who come with the seasons. We have some undocumented workers, and when the INS comes in, that scatters them. We immunized as many as we could."
In addition to the mass immunization programs, surveillance of women of childbearing age has increased.
Lutz said there have been no cases reported in Iowa for several weeks. Immunizations were also offered at packing plants here. "We had an opportunity to get into the packing plants and immunize, and we pretty much did that throughout the state. I think that helped, because a lot of the workers move from plant to plant."
Whether the immunization program will be completely effective depends on how long county health departments can continue. "Certainly there are new workers coming from Mexico all of the time," Lutz said. "In some cases, (county agencies) are continuing to immunize people as they come in."
In Minnesota, where suspected cases are still being evaluated, thousands of vaccinations have been given, but health department officials consider fighting rubella as a long-term project.
"We've been trying to enlighten our providers to have a heightened suspicion of rubella if they see someone with a rash illness," Ehresmann said.
Concerning vaccinations, she said a grass-roots approach may be helpful. "Word of mouth is more effective in reaching these populations. There's a distrust of government. If people can hear about it from their own people and go to a neutral site to get vaccinated, they're much more willing to do it. Our local counties are working with clinics to serve these populations."
You can express your views on this article, or other relevant themes, in the Infectious Diseases in Children Specialty Forums.