Dear doctor

Make them buzz off

Q I will shortly be travelling through Thailand and Indonesia. I have read that taking vitamin B1 supplements makes your skin less tasty to mosquitoes. I would like to know if this is true.

A I couldn't find any malaria experts who'd heard of vitamin B1 acting as a mosquito deterrant - you may be on to a great discovery there. Apparently, mosquitos that transmit malaria only bite from dusk until dawn. That means long-sleeved T-shirts, and trousers tucked into socks from the moment the sun goes down. Sleeping under a mosquito net, especially one sprayed with the chemical permethrin, is a good idea, as is burning a coil which releases smoke and rubbing repellent creams onto exposed bits. I'd want to take antimalarial drugs as recommended by a GP surgery or travel clinic.

Baby infection

Q I was alarmed by a recent episode of Coronation Street in which a newborn baby died from an infection picked up from its mother during labour. I understand this infection can lie dormant in the mother and not be detected. I'm pregnant with my first baby and am very worried. Can you reassure me?

A Coronation Street has highlighted a potentially serious bacterial infection called Group B streptococcus (GBS for short). Estimates vary, but around 5-10% of us carry this bug. A tiny but unpredictable proportion of pregnant women carry a virulent type in their vagina which can pass to the baby during labour, causing life-threatening blood poisoning (septicaemia) to mother and baby. GBS can be detected by a vaginal swab. It is treated by giving antibiotics into a vein during labour. Treating it earlier in pregnancy with oral antibiotics is too unreliable. Only those considered to be at high risk are screened in this country: pregnant women with vaginal discharge; evidence of GBS - eg in the urine; those who get a sudden temperature during labour or those who've had previous unexplained rupture of membranes and premature labour. It is likely that all pregnant women will soon be offered a vaginal swab. Meanwhile, anyone who wants the test should ask.

For more info: www.gbss.org.uk

Trussed up

Q I've got hernia in my groin and have been told to have it operated on. I'm terrified of hospitals and wondered if I could get a truss.

A Chances are you've got an inguinal hernia; a bulging of abdominal contents through a defect in the abdominal wall. Hernias never just go away and always get bigger with the passage of time. Trusses are uncomfortable and very unfashionable-aesthetically and medically. I'd get the hernia repaired as soon as possible; if you're generally fit you should be able to have day case surgery and spend very little time in hospital.

It's in the blood

Q I'm a 52 year old man with high blood pressure that seems particularly difficult to treat. My GP said that it was because I'm black, which I found offensive.

A The remark almost certainly wasn't meant to sound offensive, but why not tell your GP how it made you feel? The fact is that many caucasians with high blood pressure have high levels of renin, a hormone produced by the kidneys. Two groups of drugs commonly used to treat high blood pressure, beta blockers and ACE inhibitors, work by lowering this renin level. But many black people share an inherited disposition to low renin levels and so these drugs don't tend to work well. Thiazide diuretics such as bendrofluazide, or a calcium channel blocker such as nifedipine, can work more effectively. Meanwhile, restrict salt, cut down on alcohol, exercise regularly, lose excess weight and cut down on cholesterol and smoking.

Fair, fat and 40?

Q My mum developed gallstones and had to have her gallbladder removed. What can I do to prevent them?

AI was taught at medical school that gallstones afflict those who are "fair (ie female), fat and 40". But a recent US study showed that the higher your intake of vitamin C, the less your risk of gallstones.

These answers are intended to be as accurate and full as possible, but should never be used as a substitute for visiting a doctor and seeking medical help. If you have a question for Dr Robinson, email drann@dircon.co.uk or write to her c/o The Health Editor, The Guardian, 119 Farringdon Road, London EC1R 3ER. She regrets that she cannot enter into personal correspondence.

Thanks to guardian.co.uk who have provided this article. View the original here.