Chickenpox: How it's spreading, why it needs immediate medical care, and how to spot it

When Leia, then three, had a temperature and a few spots, Lopez knew this was it. “I had to go away for four days on a business trip. I felt extremely guilty, but I wasn’t worried. Her dad was looking after her and I felt chickenpox is like a bad flu with itchy spots, she’ll get better and then her brother will get it.”

This is what happened: Within 10 days, Jake, then only two, caught it. “He was miserable. He had a high temperature. The worst was not knowing what he was feeling, because he was so young. To this day, he has a mark on his face from one of the blisters.”

But the illness ran its course, Jake got better, and Lopez recalls the whole chickenpox experience as nothing major. “I don’t think it’s a major worry: Chickenpox is something you just get done with.”

Hospitalisations up 126%

Dr Niall Conroy, adjunct professor of public health at University College Cork, agrees that chickenpox is mild in most children, even if they are miserable, and they can be managed at home. “However, some children do become very unwell with it and there can be serious complications,” he warns, pointing to a 126% increase in chickenpox hospitalisations in 2023 compared with 2022.

Caused by the varicella-zoster virus, chickenpox is highly contagious. Conroy says: “It can cause an itchy, blister-like rash, mostly affecting children under the age of 10, though you can get it at any age. Estimates put the annual number of cases in Ireland at around 58,000. About one-third of those who have had chickenpox will develop shingles at some point in their lifetime, due to the virus reactivating.”

One in every 250 cases requires hospitalisation, because of complications. An Infectious Disease Notifications report from the Health Protection Surveillance Centre in 2023 shows 170 hospitalisations for chickenpox, compared to 75 the previous year.

Conroy suspects the rise in hospitalisations is due to the pandemic and the years when we were isolating and cocooning, rather than socialising and building up resistance. “Every spring, the population is exposed to chickenpox. We didn’t get that during covid, so we missed out on an immune boost and our collective immunity to chickenpox has been a bit less over the last few years.

“And then, after covid, people did want to socialise and get the kids out and about doing things. So it all just took its toll. I suspect things will settle over the next few years.”

So why would children need to be hospitalised for chickenpox? In a small number of cases, chickenpox can develop a secondary bacterial infection, because the scratching of itchy blisters carries a risk of serious infection: invasive group A streptococci (iGAS).

Conroy says an uptick has been noted in the number of iGAS cases over the last year. “Some of this was associated with chickenpox, though much of it wasn’t. Essentially, all that scratching can open up a lot of routes of entry for bacteria to get deeper into the skin, where they can cause nasty infections, and the child might need to be admitted for intravenous antibiotics.

“Occasionally, these skin infections can spread into the bloodstream. Then there are other, quite uncommon complications, like infection of the lungs and even the brain. Very small children, in particular those who catch chickenpox around time of birth or in the first week of life, are also at high risk of very severe disease.”

Adolescents tend to feel more unwell during infection and so do adults. But Conroy says the real risk groups for severe disease are pregnant women, because of congenital varicella syndrome.

Infection can overwhelm newborn babies due to their very underdeveloped immune system, and in immuno-compromised people, infection can spread to vital organs, becoming very serious.

Chickenpox parties

Research carried out by Ipsos Behaviour & Attitudes, on behalf of healthcare company MSD Ireland, found that 50% of people are concerned about their children contracting chickenpox. And yet, Conroy says some parents have been holding chickenpox parties for as long as he can remember.

“I don’t think there’s any great benefit in infection happening earlier: Under-fives are more at risk for severe disease and it’s usually these small children that attend such parties. Also, it’s not very pleasant for the miserable child with chickenpox, while they’re sick, to be expected to play with six or seven of their energetic little friends. Ultimately, most people end up getting chickenpox one way or another.”

The MSD research also found that three days of annual leave, on average, are required to care for a child with chickenpox, and that sick children need as many as 10 days or more out of school or childcare.

The isolation period was particularly relevant for Lopez, who is from Spain. “We had a flight booked to go to Spain for about 10 days after Jake caught chickenpox. We weren’t sure if we would be able to go. We needed a letter from the doctor to travel. Thankfully, we got the OK to go.”

Chickenpox tends to peak in Ireland from around January to May, but this can change somewhat from year to year.

“There’s always some of it around,” says Conroy. While it is difficult to avoid the complications of chickenpox, because they can be unpredictable, Conroy urges parents to be vigilant for warning signs.

“If your child has difficulty breathing or is difficult to rouse, or seems particularly lethargic, then it’s definitely time to get help. Often, secondary infections first declare themselves when the initial fever settles for a day or two, and then starts spiking again. Keep an eye on the skin for evidence of secondary infections, too, which often look very red,” he says.

Most of the public-health advice is around keeping people with chickenpox symptoms, or who feel unwell, away from vulnerable groups (pregnant women, babies, and immune-compromised people).

Conroy emphasises how important it is, if bringing a child to the GP or emergency department, to let the surgery or hospital know that you think they have chickenpox, before arrival, so that you are not placed in the waiting room with high-risk people.

His advice on vaccination? “This is only available privately at the moment, mostly from GPs and pharmacies. It’s expensive (about €150), and two doses are required.

“It is generally only given to children older than a year. But for families that can afford it, it’s very good at preventing a fairly unpleasant disease. It might also be cost-effective for some people, as a child’s chickenpox often means a parent taking about a week off work to look after them.”

• For more information about chickenpox, visit chickenpoxaware.ie