ALL East Riding schools have been asked by the director of public health to issue a measles alert to families.
Parents are being urged to ensure their children are vaccinated against measles after serious outbreaks in other parts of the country and an unexpected number of cases in the East Riding.
The number of cases in the East Riding is above the three-year average, with 17 cases in the past two months.
Hull has had only two cases so far this year but the city council is considering writing to its schools next week to issue a vaccination plea to parents.
Dr Tim Allison, director of public health in the East Riding, said: "There has been more cases than expected in North Yorkshire and the East Riding.
"We are above the three-year average, the lowest it has been is about five cases and the highest on the three-year average is about 15.
"Over the past few weeks, the number of cases has fallen but we are still concerned given the number of cases in other parts of the country."
Following serious outbreaks of measles in Wales, outbreaks are now occurring widely in England, with teenagers the most affected.
This is because many missed out on MMR (measles, mumps and rubella) vaccinations in the late 1990s and early 2000s when the vaccine was mistakenly linked to cases of autism.
Dr Allison said: "There's a group of people who are not vaccinated and it is very important to make parents aware of the benefits of vaccinating children who are either not vaccinated at all or who have had only one vaccination."
Measles outbreaks are a serious concern across the country with up to a million children and young teenagers potentially vulnerable to infection, especially as they are going into secondary school where the spread of infection is much more likely.
Measles can cause serious complications including pneumonia and very serious complications, such as inflammation of the brain, which can be fatal.
Dr Allison said: "It is not very common to be fatal but it can be.
"There are groups that are particularly vulnerable, pregnant teachers for example, it's not just children.
"It is more likely to be serious in pregnant women, people whose immunity is not working properly and babies under a year of age."
There have been some linked cases in the East Riding but public health officials are not declaring an outbreak.
Dr Allison said: "There have been some linked cases but we don't have an outbreak at the moment.
"The slight increase and the odd episode that we have had of some linked cases are an indication that we can't be complacent."
About 95 per cent of children in the East Riding have been vaccinated.
Parents are being urged to contact their GP practice if they are unsure if their child has received two doses of the MMR vaccination. The vaccination is free on the NHS.
