Your health questions answered

An itchy problem

My six-year-old son may have threadworms, as he has been scratching a lot. A friend told me to get mebendazole. How can I ensure that our other two children don't catch them too?

Threadworms look like small pieces of thread. They live happily in the intestine of humans. At night, they venture out on to the skin around the anus to lay their eggs, which causes it to become intensely itchy. If you scratch – it's hard to resist – the eggs get on to your hands and under your fingernails. Children like to lick their fingers, and this allows the eggs the re-enter the body, and so the cycle goes on. Three things help to break the life cycle of threadworms: wearing pants in bed (to prevent the eggs from getting on to the fingers); washing hands and scrubbing fingernails with a brush several times a day, particularly after going to the toilet; and treating the whole family with mebendazole (also known as Vermox, and available from chemists) to kill any threadworms living in the intestine.

Sight concern

Having lost the sight in one eye when I was17, due to a detached retina, I am concerned about the sight in my other eye. Early this year, I was diagnosed with age-related macular degeneration (AMD) in that eye and referred to hospital, where I had scans but no treatment. Finally, I was referred to a specialist who did another scan. He suggested an injection into the eye, but said there was no guarantee it would work, and I could lose my sight altogether.

Age-related macular degeneration gradually destroys vision in the central part of the retina (the macula), responsible for sharp vision. AMD comes in two forms – wet and dry. Some treatments are available for wet AMD, but there is currently no effective treatment for dry AMD. People who are developing wet AMD sometimes notice that straight lines appear wavy. One of the first symptoms of dry AMD is slightly blurred vision. The newest, and probably best treatment for wet AMD is a drug that is injected into the eye to stop the development of new fragile blood vessels, the cause of visual loss. The new treatments are not widely available on the NHS, but the RNIB is campaigning to change this. To find out more, see www.rnib.org.uk.

Please send questions and suggestions to A Question of Health, 'The Independent', Independent House, 191 Marsh Wall, London E14 9RS; fax: 020-7005 2182; email: health@independent.co.uk. Dr Kavalier is unable to respond personally to questions

Readers write

A letter about cystitis prompted lots of readers' tips:

PN writes: Pass water as soon as possible after having sex.

AK from Somerset: Take a teaspoonful of bicarbonate in a glass of water every hour, and a glass of plain water on the half-hour. It works. Symptoms abate within hours, but it takes a few days (three doses a day) before pain goes. One dose at the first hint of cystitis usually heads off an attack altogether.

MP from London: To ease the pain, try one hot-water bottle on your back and another one between your thighs.