Our guide to swine flu photolibrary.com

YOU could be ­forgiven for thinking swine flu was so last month, with headlines drying up quicker than the throat of a hapless victim.

But the reason the virus is not being reported as much is because of the school ­holidays. Since the country’s children have broken up for the summer, the number of new swine flu cases has fallen steeply.

Estimated figures from the Government revealed there were just 25,000 fresh cases two weeks ago – compared to 30,000 the week before.

The virus has ­affected children the most because they spread it between themselves in the playground, mainly through poor ­hygiene (have you ever seen a four-year-old carrying a hand sanitiser?).

But even though they may be safer at home with the family, that doesn’t mean the threat is removed from adults. And 25,000 is still a large number of new cases.

“Infection rates may be down but these are largely in children. Adults are still at risk, so it’s important to keep practising good hygiene,” says Keith Neal, professor of ­epidemiology and infectious diseases at the University of Nottingham.

But if you’re unlucky enough to spend five days staring at your bedroom ­ceiling, you might find it ­comforting to know what’s going on inside your body.

On the other hand, if you’re ­feeling bushy-tailed, then ­understanding the ­mechanics of flu and how it’s transmitted may just keep you off the Tamiflu.

“The symptoms of flu, like a fever and shivering, are caused by the body’s own defence mechanism,” says Neal.

So it’s a sort of internal friendly fire that’s causing you to feel like death warmed up.

Here, the experts explain the battle that is going on ­under your skin.

1. Getting it: bug alert

You can catch swine flu one of two ways: by breathing in airborne bugs or touching an infected surface such as a door handle and then putting your fingers to your mouth. “The bug lasts up to 24 hours on a hard surface like a Tube pole, but soft surfaces like clothes tend to damage the structure of viral cells, so they don’t survive longer than two hours,” says Dr Brian McCloskey, director of the Health Protection Agency in London.

Normally, flu bugs do not survive long in ultra-violet light, which is why we encounter fewer in the summer, but swine flu seems less affected by the sun. It is expected to spread more easily in the winter. Where it is now winter – Australia and Argentina, for example – there has been a big increase in cases

2. Mouth: portal

The virus does not attack the cells lining the mouth which are more robust, instead it goes straight for the more sensitive throat cells. It’s only when you’re near a flu victim who expels germs from the throat (the viral warzone) by coughing or sneezing, that the virus is passed on. An exchange of saliva through kissing alone will not pass on the virus – but hold your breath because breathing just might.

3. Throat: warzone

A sore trachea is one of the most common symptoms of swine flu. The virus is respiratory, which means it latches only on to the cells lining your airways, in the same way that the hepatitis virus attacks only the liver, and not, say, your armpit. The virus kills the throat cells, causing inflammation and creating gaps between cells that are open to secondary infections. Cold air and hot drinks rake over the raw surface. Underlying health conditions amplify the effect. “Chronic asthma and smoking will have damaged the lining of the airways, which means it’s easier for the virus to penetrate the cell wall,” says McCloskey.

4. Immune system: Commmand HQ

Once the infection is detected, molecules called cytokines signal the immune system to act. White blood cells in the bone marrow go into overdrive producing antibodies to fend off the infection.

The idea is to produce an antibody that locks on to the two proteins on the virus wall (the H and N in H1N1 are proteins).

Some elderly people, who were exposed to a similar strain of swine flu in 1957, already have antibodies that recognise the pattern of H1N1 proteins. So their immune systems are primed and have a head start.

The rest of us have to produce antibodies from scratch. They flood the site of infection, but it takes about three days before there are enough antibodies to overwhelm the virus.

There are immune-boosting supplements on the chemist shelves containing antioxidants and phytonutrients, known to reduce the risk of cancers and infections, but fruit and vegetables such as red onions and blueberries contain these nutrients.

Exercising when you’re not ill will boost your immune system too. thelondonpaper’s Urban Doc Dr Anjlee Sheth says: “If you’re eating and drinking properly and taking regular exercise, I wouldn’t worry too much about supplements.”

5. Fever: firefight

Becoming hot is thought to be the body’s opening salvo at beating the infection. It’s the firefight before the antibody cavalry arrives, usually in two to three days. “A fever is a common approach by the body to infection, but it’s not known whether it impairs the growth of a germ or makes the body’s defence more efficient,” says Neal. Shivering is also your body’s way of generating heat. If you feel too hot, a cold shower won’t do much good. “This stops the body losing heat by sending blood away from the skin. You may feel cooler immediately after but you’ll soon be hot again.

“If you feel uncomfortable, try paracetamol, which lowers the body’s temperature.” Your internal thermostat is regulating your fever on its own by sweating (the moisture cools the skin surface), but this can cause dehydration so it’s important to keep drinking plenty of fluids.

6. Coughing: defence mechanism

A dry cough is an involuntary reflex. Normally, it’s a defence mechanism to expel a foreign body, like dust, that has entered the airways. But when the throat is infected, your body registers the inflammation as a foreign body tickling the airways.

Dr Charles Levinson, medical director of DoctorCall.co.uk, says: “A dry cough is like hiccups and can be suppressed if you try hard enough.”

A wet cough, however, is when goblet glands produce an excess of mucus in the throat. You should be hacking up clear mucus if you have a viral infection. Yellow or green phlegm, however, is a deposit of dead bacteria – this means you’ve succumbed to a secondary bacteria bug.

7. Fatigue: a sign

Malaise, exhaustion and muscle aches are key signs of flu, as opposed to a cold. They are thought to be the side effects of the chemical interferon, which is produced to fight the infection.

“Fatigue could be your body’s way of telling you to relax,” says Levinson. “If you exercise or work in a stressful job, you’re using vital glucose and oxygen reserves needed to produce antibodies.”

8. Loss of appetite: casualty

While your body’s fighting an all-out war, it tends not to be too inclined to digest food, which could divert the body from battling the virus. “Losing a few pounds is not going to harm you,” says McCloskey. “The important thing is to keep your fluids up to stop dehydration.”

Doctor’s orders

If you think you have swine flu, call the National Pandemic Flu Service on 0800 1513 100 or go to www.direct.gov.uk/pandemicflu. It is important to rest and stay away from other people.