Postgrad Med J: first published as 10.1136/pgmj.51.602.830 on 1 December 1975. Downloaded from Postgraduate Medical Journal (December 1975) 51, 830-837. Bites and stings in travellers H. ALISTAIR REID O.B.E., M.D., F.R.C.P.E., F.R.A.C.P., D.T.M. & H. Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 SQA Summary TABLE 1. Diseases acquired by bites and stings As a rule, bites and stings in travellers are merely a Vector Systemic disease transmitted nuisance. But it is sensible to be informed about the Class INSECTA more serious possibilities which can result. Systemic Order DIPTERA diseases can be transmitted, the skin lesions from Mosquitoes Malaria, filariasis, arboviral insects can be troublesome and finally, some bites and infections stings can cause envenoming. Thus, the bather may be Sandflies Leishmaniasis, bartonellosis Blackflies Onchocerciasis harmed by venomous fish stings, sea urchins, jellyfish Midges Filariasis and in Asian-Pacific waters by sea-snakes. Land Tsetse flies African trypanosomiasis Protected by copyright. hazards include bites or stings by scorpions, spiders, Horseflies Loaiasis, tularaemia ticks, centipedes, bees, wasps, caterpillars and snakes. Order ANOPLURA Lice Typhus, Q fever The main clinical features of such bites and stings, Order SIPHONOPTERA including treatment and prevention, are outlined. Fleas Plague, typhus Order HEMIPTERA Introduction Bugs American trypanosomiasis Class ARACHNIDA Few, if any, travellers will escape bites or stings, Order ACARINA particularly if they travel to the tropics or sub- Mites Typhus tropics. The catalogue of disasters associated with Soft ticks Relapsing fever insect troublemakers should alone be enough to Hard ticks Typhus, arboviral infections make one stay at home (Harman, 1971). Other Dogs, bats, etc. Rabies common animals potentially noxious to the traveller include jellyfish, sea urchins, venomous fish, sea snakes, ticks, mites, scorpions, spiders, centipedes and Skin lesions land snakes. However, the traveller may take heart Insect bites are a world-wide scourge to travellers http://pmj.bmj.com/ from statistics in Rhodesia where the annual death who can become rapidly sensitized so that firm itchy rate from road accidents is seventeen times that papules form within 24 hr of each bite-usually caused by animals (Castle, 1971). Moreover most of multiple bites. After further exposure immediate the deaths caused by animals were provoked by man weals may develop and subsequent bites may provoke rather than by the animal. Undoubtedly, the both types of reaction indefinitely. Alternatively, greatest animal danger to travellers is man (followed reactions may decrease; first, the delayed and then in Rhodesia by the crocodile). Bites and stings can the immediate responses are reduced or lost (Har- on September 23, 2021 by guest. harm the traveller, causing (1) trauma, physical and man, 1971). For local treatment calamine lotion is mental (fright), (2) transmission of systemic disease, suitable; antihistamines can cause sensitization and (3) skin lesions, (4) envenoming. photo-sensitization and are not recommended. But if lesions are widespread, antihistamines by mouth Transmission of systemic disease are probably helpful, such as chlorpheniramine Systemic disease is the most serious potential maleate tablets (Piriton) 4-16 mg daily. For more harm to the traveller from bites and stings. Although severe local reactions a steroid such as betamethasone the diseases in Table 1 would be acquired in the valerate cream (Betnovate) may be needed-pro- tropics and sub-tropics, symptoms often start after vided there is no sepsis or ulceration. Infection of the traveller has returned home. The most important scratched lesions must be discouraged, if necessary disease is falciparum malaria, dealt with in the by a bandage. If infection has been established, previous paper. systemic and local antibiotics may be needed. Postgrad Med J: first published as 10.1136/pgmj.51.602.830 on 1 December 1975. Downloaded from Bites and stings in travellers 831 Clothing helps to prevent insect bites especially bites and stings are fairly simple and may be divided round the ankles. A useful repellant is diethyltolu- into: amide in a liquid evaporating base such as 70% (1) Fright effects are present in virtually all ethanol. An insecticidal aerosol spray is worth venomous bites and stings. Often there is fear that taking on travels. rapid, painful death is inevitable. (2) Venom effects may be summarized: Myiasis (i) Local, mainly vasculotoxic (pain, swelling, This is the condition produced by fly larvae in- sometimes necrosis). vading living tissue. The Tumbu fly, Cordylobia (ii) Systemic vasculotoxic (bleeding, some- anthropophaga, is widely distributed in Africa South times shock). of the Sahara. The female fly lays eggs on sand or (iii) Systemic neurotoxic (autonomic effects; soil contaminated by urine or excreta; larvae from neuromuscular block of muscles for vision, the eggs can live 1-2 weeks in~the soil before they swallowing, breathing). become attached to a host. They burrow just under (iv) Systemic cardiotoxic or myotoxic effects the skin, leaving their posterior breathing openings (less commonly). on a level with the surface. The lesions may appear Systemic vasculotoxic effects are typical ofviperine only on return from travelling and resemble boils snakebite poisoning, and the neuromuscular blocking but do not throb (although they itch), and each has effects are typical of elapid snake bite poisoning. a small hole in the centre. The larvae grow in the Venoms of sea snakes and of some Australian elapid skin for about 2 weeks then wriggle out to form a snakes are mainly myotoxic. The venom effects of puparium. The adult flies emerge 10 days later; bites and stings other than snake bite chiefly involve they resemble bluebottles except for a yellowish local vasculotoxic features, autonomic neurotoxic features, and sometimes cardiotoxic effects. Ifpoison- colour. Man may acquire the larvae from con- Protected by copyright. taminated sand, clothes or bed linen. An adhesive ing is very severe, acute renal failure can occur in occlusive dressing kills the larvae which in time are most types of envenoming. shed naturally from the skin (Radcliffe, 1972). Although the effects of venomous bites and stings Larvae of several other flies can cause similar lesions in man depend on the type of venom, a much more including subconjunctival lesions. important factor is the amount of venom injected. Clinicians should realize that, although fatalities and serious poisoning can occur, more commonly (and Chiggers fortunately) little or no envenoming results from The chigger sandflea, Tunga penetrans, occurs in venomous bites and stings in man. In the latter cases, tropical Americas, Africa and India. The impreg- fear often dominates the clinical picture. nated female flea burrows into the skin of the first warm-blooded animal she encounters (in man, usually the foot), and grows to the size of a small Venomous bites and stings in the sea pea. A painful boil-like lesion with a central black Fish stings dot results, and secondary infection is common. The Venomous fish stings are common in the tropics. http://pmj.bmj.com/ best treatment is to enlarge the entrance orifice with In coastal waters where the sea bed is mud or sand, a needle and enucleate the entire insect. Walking catfish occur-so called because they have whiskery bare-footed should be avoided. mouthparts. They have serrated spines in their fins which can inject venom. Stingrays have a flat Venomous bites and stings triangular-shaped body varying in diameter from a General considerations few cm to 3 m. When trodden on they whip forward Venomous creatures can secrete venom in a gland their tail which has a serrated sting on it. In coral or in specialized cells, and can deliver this venom reefs, even more venomous fish are found such as on September 23, 2021 by guest. during biting or stinging. All venoms contain a stonefish and scorpion fish. They have multiple complex mixture of toxins which can be experi- venomous stings along their backs. The main effects mentally fractionated into enzymes and polypeptides of stings by these fish is an intense and often agoniz- with widely varying biological and pharmacological ing local pain. Sometimes the sting becomes de- effects. Readers interested in details ofvenoms should tached and remains embedded, leading to a chronic consult the admirable review by Minton (1974). The discharge. Local necrosis sometimes occurs with complex and sometimes conflicting experimental scorpion fish stings. effects of venom fractions are not always relevant to The most effective treatment for the local pain of the clinical problem of envenoming in man. Indeed, venomous fish stings is hot water. The part stung is some experimental findings can mislead clinicians. immersed in water as hot as the patient can bear. In man, the important clinical effects of venomous The pain is relieved within seconds and the part Postgrad Med J: first published as 10.1136/pgmj.51.602.830 on 1 December 1975. Downloaded from 832 H. Alistair Reid stung must be quickly removed from the water to four body corners, it is translucent and difficult to avoid blistering. It should be reimmersed as pain see in the water. Sea-wasps of the family Chiro- recurs (within seconds at first, later within minutes). dropidae, have been found in tropical waters of all This procedure should be continued until the pain continents in the world. Physalia, or the Portuguese no longer recurs (usually about 30 min). It is im- man-o'-war jellyfish, has a coloured float from which portant to explain details of this simple but highly numerous minor tentacles hang, together with a effective treatment to the patient, who should be single main tentacle which can be very long, up to given a can of water recently brought to boiling 30 m in length. Although it has an evil reputation, point. This should be added to the immersing water severe poisoning seldom follows the stings of the to keep it as constantly hot as he can bear.