The most dangerous biting insects in parts of Botswana are mosquitoes, because they can transmit malaria, yellow fever, dengue fever and a host of other diseases. Research has shown that using a mosquito net over your bed, and covering up exposed skin (by wearing long-sleeved shirts, and tucking trousers into socks) in the evening, are the most effective steps towards preventing bites. Bed-net treatment kits are available from travel clinics; these prevent mosquitoes biting through a net if you roll against it in your sleep, and also make old and holey nets protective. Mosquito coils and chemical insect repellents will help, and sleeping in a stream of moving air, such as under a fan, or in an air-conditioned room, will help to reduce your chances of being bitten.

DEET (diethyltoluamide) is the active ingredient in many repellents, so the greater the percentage of DEET, the stronger the effect. However, DEET is a strong chemical. Just 30% is regarded as an effective, non-toxic concentration. It will dissolve some plastics and synthetic materials, and may irritate sensitive skin. Because of this, many people use concentrated DEET to impregnate materials, rather than applying it to themselves. An alternative to this is to use Bug Guards – wrist and ankle bands containing 100% DEET in capsule form. The capsules break on movement, but the chemical never touches the skin. One pack contains four bands, which when opened, last for two weeks. Mosquito nets, socks, and even cravats can be impregnated and used to deter insects from biting. Eating large quantities of garlic, or cream of tartar, or taking yeast tablets, are said to deter some biting insects, although the evidence is anecdotal – and the garlic may affect your social life.

Dengue fever

This mosquito-borne disease may mimic malaria but there is no prophylactic medication available to deal with it. The mosquitoes that carry this virus bite during the daytime, so it is worth applying repellent if you see any mosquitoes around. Symptoms include strong headaches, rashes and excruciating joint and muscle pains and high fever. Dengue fever only lasts for a week or so and is not usually fatal. Complete rest and paracetamol are the usual treatment. Plenty of fluids also help. Some patients are given an intravenous drip to keep them from dehydrating. It is especially important to protect yourself if you have had dengue fever before. A second infection with a different strain can result in the potentially fatal dengue haemorrhagic fever.

Snakes, spiders and scorpions...

Encounters with aggressive snakes, angry spiders or vindictive scorpions are more common in horror films than in Botswana. Most snakes will flee at the mere vibrations of a human footstep whilst spiders are far more interested in flies than people. You will have to seek out scorpions if you wish to see one. If you are careful about where you place your hands and feet, especially after dark, then there should be no problems. You are less likely to get bitten or stung if you wear stout shoes and long trousers. Simple precautions include not putting on boots without shaking them empty first, and always checking the back of your backpack before putting it on.

Snakes do bite occasionally, and you ought to know the standard first-aid treatment. First, and most importantly, don't panic. Most snakes are harmless and even venomous species will only dispense venom in about half of their bites. If bitten, you are unlikely to have received venom; keeping this fact in mind may help you to stay calm.

Even in the worst of these cases, the victim has hours or days to get help, and not a matter of minutes. He/she should be kept calm, with no exertions to pump venom around the blood system, whilst being taken rapidly to the nearest medical help. The area of the bite should be washed to remove any venom from the skin, and the bitten limb should be immobilised. Paracetamol may be used as a painkiller, but never use aspirin because it may cause internal bleeding.

Most first-aid techniques do more harm than good; cutting into the wound is harmful and tourniquets are dangerous; suction and electrical inactivation devices do not work. The only effective treatment is antivenom. In case of a bite which you fear may be both serious and venomous:

• Try to keep calm. It is likely that no venom has been dispensed.
• Stop movement of the bitten limb by applying a splint.
• If you have a crepe bandage, firmly bind up as much of the bitten limb as you can. Release the bandage for a few minutes every half-hour.
• Keep the bitten limb below heart height to slow the spread of any venom.
• Evacuate the victim to a hospital that has antivenom.
• Never give aspirin. You may offer paracetamol, which is safe.
• Do not apply ice packs.
• Do not apply potassium permanganate.

If the offending snake can be captured without any risk of someone else being bitten, take it to show the doctor. But beware, since even a decapitated head is able to dispense venom in a reflex bite.

When deep in the bush, heading for the nearest large farm or camp may be quicker than going to a town: it may have a supply of antivenom, or facilities to radio for help by plane.