AGNES Munyiva is a prostitute. Over the course of the last 30 years has had (unprotected) sex with more than 2,000 men in a slum in the Kenyan capital Nairobi.
And yet in a country with a HIV positive rate of about 7%, she has not got infected.
Agnes was juts one of a group of prostitutes that scientists from the University of Manitoba first came across when conducting research on STIs in the area in the 1980s.
Such was the researchers’ fascination with the women that they decided to stay on, offering free health care in exchange for research subjects.
Though not their initial aim, the researchers discovered that some prostitutes were immune from HIV and in a study published in 2012, they concluded that the prostitutes’ ability to fight off the virus was down to unique proteins that were found in their bodies.
The study was groundbreaking. Not only did it shed light on HIV/AIDS but also on the complex world of viral infection and the immune system.
According to Cliona O’Farrelly, professor of comparative immunology at Trinity College Dublin, the first thing we must realise is that no two individual immune systems are the same.
“There are huge differences in each individual’s ability to respond to either bugs or the environment or stress,” she points out.
“Because of that our immune systems react very differently and so we ourselves end up in different states of health or disease.
“You start off with a set of genes, a code for different types of immune cells and different types of immune molecules and some genes produce more or better of those cells or molecules.”
In other words, some people are just born luckier than others.
“It’s clear that some people are resistant to viral infections that other people get,” she continues.
“We’re working on a big project at the moment involving Hepatitis C and studying why some women who were given blood between 1977 and 1979 didn’t get infected while others did. Understanding why they didn’t get infected could be really important.”
Prof O’Farrelly believes research into recently discovered microorganisms that exist in different parts of our bodies might be key to understanding our immune systems.
“Most microbes in our environment are harmless and more than that are in fact beneficial,” she explains.
“We have a huge number of microbes in our guts, our mouths and our skin, known as microbiomes — thousands of them that are working to keep us healthy.”
There are trillions of them but just how many of them are useful and how many are simply just there in a symbiotic capacity is, at this stage at least, simply impossible to know.
An article published in Scientific American in 2009 entitled Bugs Inside asked the question: what happens when the microbes that keep us healthy disappear?
The authors claimed that “with rapid changes in sanitation, medicine and lifestyle in the past century, some of these indigenous species are facing decline, displacement and possibly even extinction.”
A key problem is the overuse of antibiotics which should only be used for bacterial infections but are often used (ineffectively) against viral infections resulting in the killing off of potentially good microbiomes.
So how can we tell the difference between bacteria and viral infections?
“It’s a tricky one,” says Cork GP Dr Phil Kieran, presenter of RTÉ’s You Should Really See a Doctor.
“It’s something that we don’t always get a 100% right and that is why a lot of GPs will turn around at the end of the conversation and say: ‘This looks very viral come back to me ... or here’s a prescription but don’t get it for another 48 hours because you likely won’t need it’.”
Time of year is also a factor, he says.
“During the winter there is often a lot more viral stuff around. Viruses are a lot more common than bacterial infections for coughs and colds.”
As Dr Kieran points out, the type of infection can only be determined by blood tests — a luxury that most GPs simply don’t have.
It’s for that reason that doctors have to ask so many detailed questions relating to the symptoms to understand the underlying cause.
In most cases, if it’s viral it will have to run its course, bacterial infections are a different matter altogether.
Professor O’Farrelly points out that incorrect diagnosis and over medicating in early life can have detrimental effects later on.
“If people have received a lot of antibiotics in childhood then they are more likely to be ill in later life,” she says.
“You’re born with a repertoire of immune cells that recognise a limited number of targets. By being exposed to lots of bugs [as a child] you’re building a bigger arsenal of immunity. So in a way getting exposed to a diversity of microbes is useful provided they don’t make you too sick.”
Research suggests that being overly sterile can have more detrimental effects on children and put them at risk of allergies and asthma, says Dr Kieran.
“But it doesn’t necessarily apply to adults. We have immune systems that will deal with most things. We’ve evolved over hundreds of millions of years without hand sanitizers or soap.
"That said, I think it’s important to be aware of [germs] and to do what you can, particularly around someone who has particular health concerns.”
So the luck of the draw and early exposure to certain germs can help. But is there anything individuals can do to boost their immune system as we age?
Professor O’Farrelly says that in recent years scientists have become more aware of how our life choices are really affecting the way those immune cells and molecules work.
“Exercise, sleep and diet are important,” she says.
“Not only does it make us feel better in our heads, it actually affects how the microbiomes in our guts are interacting with our immune system.
“Avoiding stress is another factor. Chronic stress puts pressure on the immune system and, as a result, people are more susceptible to infection.”
It is around now, as our public transport systems and offices begin to fill with the sound of coughing and sneezing, that people need to take preventative measures — though it is, of course, better to do it all year round.
On average, most adults catch two to five colds a year while children suffer between seven and ten.
As well as sleep and exercise, a diet rich in Vitamin C is thought to help the immune system.
Adults need 40mg of vitamin C a day and it can’t be stored in the body, so topping up on a daily basis is an imperative.
Blackcurrants, broccoli, Brussels sprouts, peppers, strawberries and oranges are all good sources of Vitamin C.
For a long time, it was thought that vitamin C was the most important vitamin when it came to fighting colds and flu but it now seems that vitamin D is just as vital if not more so.
A study published in the journal Archives of Internal Medicine shows that people with the lowest levels of vitamin D are the most likely to catch colds.
“In Ireland, we don’t get huge amounts of vitamin D,” says Dr Kieran.
“So during the winter it’s not a bad idea to look at addressing that by eating oily fish or taking milk supplemented with vitamin D or trying to get out into sunlight whenever it pokes its head above the clouds.”
Fish also contains zinc which prevents the cold-causing rhinovirus from lodging in the mucous membranes of the throat and nose.
A recent study published in the Open Respiratory Medical Journal found that lozenges that contained a dose of over 75mg showed between a 20% and 42% reduction in the duration of colds.
“Zinc works synergistically with vitamin C,” says nutritionist Heather Leeson, director of Glenville Nutrition Ireland.
“If you’re deficient in zinc it affects the ability of T cells and other immune cells to function correctly.”
Fans of curry will be delighted to find out that both garlic and turmeric can aid in the prevention and easing of cold symptoms. Garlic contains allicin, an antibacterial chemical that helps your body to fight colds.
A British study published in 2001 by the Garlic Centre in which 146 volunteers were given a placebo or an allicin-containing garlic supplement found that those who took the garlic capsule daily for 12 weeks suffered significantly fewer colds and recovered more speedily.
Turmeric, another curry ingredient, reduces inflammation so can ease the pain of a sore throat. The curcumin in turmeric, which makes it yellow, stimulates cells to kill bacteria.
And for dessert a good dose of manuka honey might just do the trick.
A study published in the journal Archives of Medical Research found that exposing cells of one strain of the flu virus to manuka honey appeared to reduce its growth.
For Heather Leeson, the key to topping up the immune system is variety.
“It is worth bearing in mind that different nutrients are needed for a healthy immune system,” she says.
“And these often work together. Rather than focusing on only one of the nutrients above, try to eat as wide a variety of natural wholefoods as possible.”
- Take the daily recommended dose of Vitamin C but don’t overdo it.
- Supplement your diet with Vitamin D.
- Exercise and get out even if it’s cold.
- Get more garlic and turmeric into your diet.
- Eat more oily fish.
- Sleep and try to avoid stress.
- Avoid antibiotics unless absolutely necessary.