We are in the midst of an outbreak of outbreaks. And while we're not quite in Old Testament territory yet, when watching images of deserted US cities and reading about impending flu epidemics from the east, it's easy to imagine how Pharaoh must have felt when he got on the wrong side of Moses. Even if we ignore the hurricanes, the bird flu, the spread of E coli and the superbug C difficile raise the question of where this will all end. As with all threats we have little control over, these outbreaks have caused great alarm. So what's the truth behind these epidemics, and what risk do they really pose to us in the UK?

Avian flu

In the two years to September 23 2005, 115 people in Asia have caught avian influenza (specifically the H5N1 variety), 59 of whom have subsequently died. All of the dead had come into close contact with infected birds, which is all that is needed for the virus to spread to humans. So far, so relatively unscary? Not according to the World Health Organisation, which in a report issued this month has referred to the infection as a "pandemic" waiting to happen.

And our own Department of Health has warned that if bird flu spreads further in the Far East, it may be just three months until it hits the UK. Once it has landed, experience suggests that it will take between 10 and 12 weeks from the first reported case for it to spread across the country, infecting around 25% of the population.

Immunisation offers the greatest protection and the government plans to purchase 2m doses of H5N1 vaccine along with 14.6m doses of the antiviral drug Tami flu for use in an emergency.

E coli

More than 100 Asians die of avian flu in two years, and 117 Welsh people come down with E coli in the space of a week. Should we be more worried about food poisoning than catching infections from our feathered friends? Not really.

While cases of potentially deadly strains of Escherichia coli (E coli) - a bacterium found naturally in the gut of people and animals - have tripled in the past decade, most strains do not cause illness in people. You are at greater risk of being run over on the way to buy your food than of being killed by eating it.

Most of the time it causes no more than mild diarrhoea, which usually lasts no longer than a week. But some who aren't so lucky develop a complication called haemolytic uraemic syndrome, which can cause kidney failure.

The Pennington report in 1997 put forward 32 recommendations to combat the spread of E coli, including awareness programmes for farm workers and enforced separation of raw and cooked meats in food preparation.

And for those who still pick it up, it can usually be killed by antibiotics.

C difficile

Clostridium difficile, on the other hand, loves antibiotics. It's a bacterium that lives harmlessly in the gut of around 3% of us but which spreads itself about when hospital patients treated with broad-spectrum antibiotics suffer collateral damage to their bacteria (ie the antibiotics kill off normal bacteria, not just the ones they're aimed at).

And while some get away unscathed, it will inflict life-threatening bowel inflammation on others. It's a clever beast whose spores can be transmitted via toilet seats, bedpans and the hands of hospital staff - a fact that a number of my patients can testify to.

C difficile can be treated with specific antibiotics, but as a study in this week's Lancet demonstrates, resistant strains have arisen in North America.

So, should we be scared? Of bird flu, perhaps. Influenza pandemics happen every 40 years or so and with the last in the 1960s, we're due one. But at least our government and the WHO seem prepared. Beating E coli is all about better standards of food hygiene and preparation. It's C difficile and germs like it that pose the most direct threat, as they profit from our overuse of anti-biotics. But they too could be beaten if only our dirty hospitals were a bit more clinical - and if people stopped insisting on antibiotics for every little sniffle.

Reader's problem

A reader writes: Will a young child, in its early months or years, have difficulty learning to talk if its mother tends to speak incoherently when speaking to her husband, friends and family?

Simon says: Children are programmed to develop language and so, in most cases, they will acquire a normal vocabulary whatever the quality of their mother's speech. However, poor-quality stimulation like this can be a problem if a child has a condition such as dyspraxia, which can also impair its movement, perception and thoughts. This in turn can affect the child's ability to understand words or pronounce them correctly. If a child seems to have a problem, it would be worth asking for a referral to a speech therapist. Most departments will see children over the age of two, as they should be using sentences in their speech by this age.

· To ask Simon a question, email health@theguardian.com. Simon cannot enter into any correspondence.