People with the “100-day cough” are being urged to “staff off work and school” for at least two days as cases hit a decade high.

Cases of whooping cough have seen a huge spike in Wales during the first few weeks of 2024. The NHS advice for people with the bacterial infection is to stay off work, school or nusery for 48 hours after taking antibiotics.

People who have not taken medication are advised to isolate for three weeks, the NHS says. It says babies aged six months or less are particularly susceptible to catching whooping cough, which in some cases could cause dehydration, seizures and breathing difficulties, reports The Mirror.

In January there were 135 notified cases of whooping cough in Wales, reports the BBC. This compares to 200 across the entirety of 2023.

Public Health Wales (PHW) said in a recent alert: “Whooping cough has waves of increased infection every three to four years and in the last few weeks, notifications of whooping cough have risen sharply.

“Following reduced circulation in 2020-2022, current notifications are at levels not seen since 2012 and 2015… Laboratory confirmed cases have not yet risen in line with notifications but are likely to increase as test results are reported.”

The illness could last for weeks or even months, hence the “100-day cough”. In the first few days it appears as cold-like symptoms that progress to coughing bouts, which are worse during the night.

People could find themselves emitting a “whoop” sound between bouts.

Dr Christopher Johnson, consultant epidemiologist and head of PHW’s Vaccine Preventable Disease Programme said babies under six months old are especially vulnerable to whooping cough.

He warned: “It can be very serious and lead to pneumonia and permanent brain damage. Young babies with whooping cough are at risk of dying from the disease.”

Explaining why cases in Wales seem to be rising so sharply, Dr Johnson said: “We typically see high rates of whooping cough peaking every three to four years, and with rates suppressed during the lockdowns of the pandemic we are naturally seeing a resurgence this year.

“Whooping cough is highly contagious and is spread by breathing in small droplets in the air from other people’s coughs and sneezes.”

The UK Health Security Agency says there were 220 notified cases of whooping cough as of January 14. That was up from 167 on January 7 and 137 on December 31.