Dengue recurrence rarely serious
Dr Calabresi is a GP and editor of Medical Observer. Send your queries to firstname.lastname@example.org I contracted dengue fever about 10 years ago when I was visiting Malaysia. Although quite sick at the time, I fully recovered and have been well since. I amplanning a trip to Asia early next year and was told I had to be extra careful about being bitten by mosquitoes because a second dose of dengue could be very dangerous — is this right? I thought my immunity would be strengthened by the previous infection? IT IS true that a second dengue infection can be very serious. However, this more severe form of dengue— dengue haemorrhagic fever — is very rare. Dengue fever is a viral infection spread via mosquitoes that classically involves high temperatures and muscle pains, among other symptoms. There are four serotypes, or strains, of the dengue virus, all of which can cause the disease. Once you develop the infection from one serotype, you are generally immune from getting the infection again from that serotype but you are not protected against the other three serotypes. Should you get infected with one of these other serotypes it is thought there is a risk that the antibodies you already have in your body from the previous infection could cause a severe reaction, which is the haemorrhagic fever. As the name implies this more serious disease is characterised by fever and bleeding, and can lead to shock and even death in its severest form. Fortunately it is not common and children are more at risk than adults, but nonetheless it would be wise to be extra vigilant in avoiding being bitten by mosquitoes in areas at high risk of dengue fever. I regularly get those spray-on tans to avoid looking lily white, which is my natural skin colour. Are there any long-term side effects? GENERALLY speaking, the tanning products that you apply to the surface of your skin are safe, provided you are not allergic to them. They contain synthetic or vegetable dyes that simply stain the skin, with little if any being absorbed into the bloodstream where it could affect other areas of the body. The rapid turnover of skin cells ensures that the surface skin cells stained by the fake tan will be shed within a couple of weeks. I have a pterygium growing on my right eye. It is not causing me any real trouble, although it is getting bigger. I would like to get it surgically removed but I have heard there is a good chance it could come back. I am42. Does it make any difference to the chance it will recur if I have it operated on now, or should I leave surgery until the pterygium causes problems? UNFORTUNATELY, whether you have the operation sooner rather than later, the risk that the pterygium — a fibrous growth on the eyeball — will recur is still relatively high — about 20 to 35 per cent. This is more likely in younger people. These days the removal of larger pterygia is often accompanied by a conjunctival graft which is believed to lower the risk of recurrence. Also, radiation and certain medications are sometimes used after the operation to prevent recurrence — though these can have side effects. There are things you can do to reduce your chances of the pterygium growing back, in particular avoiding the major irritant — UV light. Wearing wrap-around sunglasses, and having the operation in the winter months will help. There are also some issues other than recurrence to consider. You don’t want to leave the operation too late as the larger the pterygium, the more likely scarring will occur, and if it has encroached on the cornea this might affect your vision.