The first report surfaced early in the New Year.
A primary school-aged child was diagnosed with mumps, a relatively rare childhood infection that is easily prevented through immunization.
Within a week, there were two more cases - all from the same school as the first case. With three identified cases of mumps from the same school, the Winnipeg Health Region took action.
Dr. Bunmi Fatoye, a Medical Officer of Health with the Region, headed up the response effort. "Once we found out there was a connection between the cases, we declared an outbreak," says Fatoye. "That means you bring together the key stakeholders and plan the response."
Mumps typically causes fever and swelling of the parotid (salivary) gland on either one or both sides of the face. A relatively common side-effect of the disease is inflammation of the testicular gland. Less common, serious side-effects include arthritis and inflammation in the brain. The infection can spread quickly through contact with respiratory secretions. That may involve direct contact, such as sneezing, or contacting a surface that has respiratory droplets on it.
People infected with mumps can spread the disease for 14 to 25 days before they have any symptoms, a factor that can make the infection difficult to contain.
Given these facts, public health officials determined the best way to contain the spread of the disease earlier this year was to establish an immunization clinic at the school and another at a nearby apartment complex with lots of young families, including some people who had been diagnosed with mumps. "We quickly understood that we were dealing with a population that was under-immunized," Fatoye explains.
By the end of February 2012, a total of 11 people, mostly children, but a few adults, were diagnosed with mumps. That's where it ended. The outbreak was contained.
For public health officials like Fatoye and Dr. Carol Kurbis, the mumps outbreak was a classic case of good news, bad news. The good news was that the Region was able to quickly identify and effectively contain an emerging health risk. The bad news was that the outbreak highlighted the fact that Winnipeg's child immunization rates aren't as high as they should be.
"It's good that we are able to move so quickly. But it would be better if we didn't have to," says Kurbis, who is responsible for keeping tabs on child immunization rates and immunization programs in the Winnipeg Health Region.
The outbreak, she says, is a reminder of the need for parents to be proactive about their health and that of their children. "When you're unwell, you go to a doctor for treatment and you see the immediate benefit of that," she says. "When you're well, you don't think about the possibility of getting sick. Preventing illness may not be a priority in busy schedules."
Although the overall vaccination rate for children has been largely stable since 2001, Kurbis says a significant minority of parents don't ensure that their children get complete protection. That means some children are needlessly at risk of getting sick from a variety of infections such as mumps, measles, tetanus and whooping cough (pertussis). For example, only 60 per cent of Winnipeg children who were seven years of age were known to have received their full complement of vaccinations in 2010.
Although there is overwhelming scientific evidence to support the use of immunizations in preventing the spread of disease, Kurbis acknowledges that there is a very small minority of Manitobans who are opposed to vaccinations and are unlikely to change their minds on the issue.
Public health officials are trying to raise awareness among those who would take advantage of the Region's immunization program but may not know about it or may not be following the recommended schedule. These groups include:
- Parents with large families who may have trouble keeping track of immunization schedules for individual children.
- Populations with other socio-economic issues such as poverty or social isolation or communication barriers.
- People who move frequently.
- Newcomers to Manitoba.
Kurbis says newcomers rank high among the groups the Region is trying to reach. Part of the problem is that new arrivals often come from countries with different vaccination schedules or little public health, and may be under-immunized. Language barriers also pose a problem, making it difficult to understand the Manitoba immunization schedule or how to access support services. For example, new arrivals may not realize that they must provide their children's immunization records to their local public health office in order for them to be entered into the provincial immunization registry, which is an effective way for keeping on top of immunization schedules. Even newcomers to Manitoba from other Canadian provinces may find it confusing, as immunization schedules differ from province to province. Indeed, nine of the 11 people who contracted mumps earlier this year had no documented history of having been immunized against the disease.
As part of the effort to reach out to this community, the province and the Region are taking a number of steps, including opening a new service called BridgeCare Clinic.
Located on Elgin Avenue, the clinic works with newcomers to provide them with health assessments and teach them about Manitoba's health-care system. The clinic is especially helpful in breaking down language barriers that often get in the way of communicating important health information. It is hoped that initiatives like the Bridge Clinic can help reduce the likelihood of health issues such as the mumps outbreak.
Another challenge in achieving high child immunization levels, says Kurbis, is the complexity of vaccinations and their schedules. Some vaccines provide long-lasting immunity, while others require a booster. As well, no vaccine provides immunity for everybody who gets it. Sometimes, like in the case of the measles, mumps, and rubella (German measles) vaccine, a second vaccination is recommended to protect people who didn't respond the first time.
For example, Kurbis says about 95 per cent of children have an immune response to the first dose of measles vaccine. "The second dose will protect 99 per cent," she says. "For mumps vaccine, one dose provides protection in 70 to 80 per cent of people, but two doses will protect about 90 per cent of people."
A small number of people are still unable to have immune responses that protect them, even with multiple doses. Others, such as those with compromised immune systems or certain allergies, can't be vaccinated.
But if overall vaccination rates are high enough, those relatively few people who haven't been vaccinated or have had an immune response can be protected through a phenomenon known as "herd immunity."
Herd immunity means that because the population as a whole has nearly complete immunity, those few people who aren't immune are at little or no risk of being exposed to the disease.
Unfortunately, the herd immunity phenomenon doesn't occur for tetanus. The organism that causes tetanus lives in the soil and is commonly present in the environment. "If you're not immunized against tetanus, it doesn't really matter how well everybody else is because you can get it from the environment around you, not people."
Another factor adding to the complexity of vaccination is that not all vaccines are the same. Some, such as measles and mumps, use an attenuated (weakened) version of the live virus. These vaccines cause a mild infection of the actual disease, which tends to create a strong immune response in the body and confer a long-lasting immunity.
Other vaccines use a killed version of the virus or bacterium. These vaccines use pieces of the organism, but not the whole thing. As a result, the immune system is triggered to respond but the body is not actually infected. These vaccinations tend not to produce as long-lasting immunity, and that is why, after infant and childhood vaccinations, people still need tetanus boosters every 10 years for life.
With all those vaccinations and boosters, it can be tough to keep track. Figures from the 2010 Manitoba Immunization Monitoring System annual report show that immunization rates among infants are, for the most part, fairly high. But the rate drops for subsequent booster shots.
For example, about 87 per cent of all two-year-olds have received all the recommended measles-mumps-rubella vaccinations. But the rate drops to 70 per cent for children at age seven. Likewise, about 81 per cent of one-year-olds are fully vaccinated against tetanus, but the rate drops to about 58 per cent by age 18.
"People are good with the first four," says Kurbis, referring to vaccinations at two, four, six and 12 months of age.
But there's a booster shot scheduled at 18 months that frequently is missed. Other parents may forget to take their children in for pre-school boosters at four to six years of age.
A steeper drop-off is felt as children get older and immunizations are held in their schools. School-based immunizations, which are administered for children in Grades 4, 6 and 9, are more effective at immunizing school-age children because they receive their shots at school instead of requiring parents to take their children to a health-care provider. However, some children, especially those in Grade 9, who need a booster for tetanus, diphtheria, pertussis (whooping cough), may forget to bring home or return consent forms.
"It becomes more challenging in Grade 9 to catch those students because all of our school programs depend on the student sending a consent form home, having parents review and complete it, and bringing it back to school," Kurbis notes. "Immunizations may not be seen as important to teens, and consent forms are easily lost or forgotten in backpacks."
One of the factors leading to incomplete immunization is complacency. Most of the diseases for which vaccines are given are much less common in Canada than in the past, as a result of decades of vaccination programs. That means diseases like mumps, measles, rubella and others don't seem to be a threat.
In 2010, there was only one case of measles in Manitoba. But Kurbis notes that hundreds of thousands of people around the world still get the disease, and in 2008 alone it killed an estimated 164,000 worldwide. Canada hasn't had a confirmed case of polio since the mid- 1990s, but around the world there are hundreds of cases every year.
For parents, ensuring that your children follow the vaccine schedule isn't just good for them, says Kurbis, noting: "If the children are immunized, we will see less disease transfer to parents."
Part of the challenge for ensuring that people's vaccinations are up-to-date is that there are more diseases that can be prevented by vaccination today.
"As we have developed more and more vaccines and introduced more vaccines into the schedule, it has become more complicated to ensure that all the required vaccines and doses have been given," Kurbis notes.
For example, chicken pox has only been added to the vaccine schedule in the last decade. While many people think of chicken pox as an itchy rite of passage for children, it sometimes leads to much more serious conditions. "Every year, people are hospitalized for skin infections, pneumonia, or bone infections as a result of chicken pox," she says. "But with the vaccine for chicken pox introduced in Manitoba in 2004 we have seen fewer of these serious incidents."
Bob Armstrong is a Winnipeg writer.
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