Should parents fear the whooping cough outbreak
02:56 GMT, 10 July 2012
Parents will have been concerned by the news last week that whooping cough is on the rise.
There’s been a tenfold increase in the number of cases so far this year compared with the same period in 2010, according to the Health Protection Agency.
Furthermore, this outbreak is greater than the last major outbreak — already this year nearly 1,800 adults and children have been affected, almost double the number in the whole of 2008 (when cases of the disease last rose sharply).
What marks out today's whooping cough outbreak is that the current peak is lasting longer than normal
Worryingly, the outbreak is increasingly affecting young babies for whom the disease can prove deadly — five babies have died of it already this year.
The Health Protection Agency believes the surge in cases may be partly due to an increased awareness among doctors who have been warned to look out for the disease, but says it could also be due to waning immunity because the effects of the vaccine reduce in time.
Indeed, the rise in cases is occurring despite a good uptake of the vaccination in younger children — 96.3 per cent of two-year-olds have completed their vaccination course against whooping cough.
So just how worried should parents be
‘Cases do increase every three to four years and this is the case the world over — it seems to be a characteristic of the disease,’ says Dr Gayatri Amirthalingam, a consultant epidemiologist at the Health Protection Agency.
‘Our last major outbreak was in 2008 when we had 900 cases, so we were due another one.
'Why it goes this way we do not know, but it always has.’
It’s not the only illness that occurs in a cycle.
Dr Iolo Doull, a paediatric respiratory consultant at the Children’s Hospital for Wales in Cardiff, says: ‘Parainfluenza 3, which causes croup, also occurs in cycles peaking every other year.’
One theory is that bugs find a different ‘habitat’ or host in those other years — a strain of flu, for example, may infect humans one year then move on to pigs and chickens.
But what marks out today’s whooping cough outbreak is that the current peak is lasting longer than normal.
‘Normally, the outbreaks of whooping cough are seasonal and peak in the autumn and are over by the spring,’ says Dr Amirthalingam.
Whooping cough is a bacterial infection spread by infected droplets being sneezed through the air — just as the common cold is spread.
These droplets settle in the airways where they multiply, causing a prolonged cough.
‘What marks this apart from a normal cough is the whooping cough bacteria make a toxin that irritates the nerves around the lungs and the voice box,’ says Dr Amirthalingam.
This triggers coughing fits followed by the characteristic whoop noise.
‘It’s a really scary condition for adults, and for children — the prolonged cough that it causes can lead to people feeling as if they are fighting for breath,’ says Dr Doull.
The key to protect yourself is childhood vaccination. The vaccine is not really designed to protect older children or adults, but instead to prevent them from passing the illness to babies
Indeed, the ‘whoop’ is the sound of air being sucked back into the lungs after a coughing bout.
Typically, it begins with cold-like symptoms: a runny nose and often a temperature.
‘It can take one or two weeks before the cough begins,’ says Dr Doull.
It’s highly contagious and a patient will continue to be infectious for up to three weeks after the cough has begun.
Anyone who suspects they have whooping cough should go to their GP, who may prescribe them antibiotics.
These should ideally be given in the early stages so they kick in before the cough has begun.
As Dr Doull explains: ‘If the cough has already begun, it’s too late to give the antibiotics to prevent the cough — however, they will reduce the bacterial load, the amount of whooping cough bacteria someone is carrying.
‘Sometimes we give a person antibiotics just to make them less infectious to other people.’
While it can be an unpleasant illness for anyone, whooping cough in infants can be extremely serious — it is fatal for one in every 500 babies who develops it.
‘There is no doubt about it — whooping cough is really dangerous for infants under six months,’ says Dr Doull.
‘Babies are born with a reflux that means they stop breathing under certain conditions — it’s a way to stop them swallowing water in emergency situations and its effects diminish as we get older.
‘However, the whooping cough toxins trip this mechanism and stop them from breathing.
‘The other problem is that a prolonged coughing fit in a very young baby can in effect empty their body of oxygen, which leads to brain damage or a fit.
‘Whooping cough is less serious the older you become because your lungs are bigger and your immune system is better able to fight it off — but even among teens and adults the coughing, which can last three months or more, can be severe enough to burst blood vessels in the eyes or cause nose bleeds.’
So how can you protect yourself
The key is childhood vaccination. The vaccine is not really designed to protect older children or adults, but instead to prevent them from passing the illness to babies.
‘Once a child is old enough to be vaccinated, the threat from whooping cough has dropped,’ says Dr Doull.
‘However, we are relying on herd immunity to keep the rates of whooping cough low to protect the small babies who are too young to be vaccinated.’
The symptoms can take between six and 20 days to develop after infection.
The key sign is chronic coughing — which may be followed by vomiting in young babies.
The strain of coughing may cause fatigue and the person may look red in the face.
There are tests that can confirm whooping cough — a blood test for levels of antibodies or a swab test of mucus from the throat.
‘However, by the time you see a child who has been coughing for three weeks, the chances are they won’t be infectious anyway so the antibodies won’t show up,’ says Dr Doull.
‘Some adults even get it and never develop the cough.
‘If you have had what you think is a cold and you have a cough that has lasted for more than three weeks, then there is a chance that it is whooping cough.’