Prophylaxis.—Do not camp in the neighbourhood of native villages. Clean the camping ground thoroughly and, if necessary, fire it. As insecticides flaked naphthalene or a strong infusion of native tobacco are useful. The latter may be used inside boots or shoes. Walking bare-foot should be avoided, as should sleeping unprotected on the ground. In the case of native carriers or porters a daily foot-parade should be instituted. Some protection is afforded by smearing the feet, especially the spaces between and under the toes, with a preparation like phenofax or with a mixture of five drops of lysol or cresol and an ounce of vaseline.
Treatment.—It is usually better to get a native to remove a chigger as long practice makes them very expert in the little operation. The latter consists in widening the skin orifice with a sharp clean needle, and freeing the flea from the surrounding tissues in order to get it out whole. If it ruptures forceps must be employed, and this is much more painful and difficult than extracting the entire insect. The infected parts should be carefully treated antiseptically.
Fungus Diseases.—There is a great number of tropical diseases due to fungi but only a few can be considered here, and these only very briefly. (1) Dhobie Itch is one of the best known and is so called because it was thought to be derived from clothes infected by the persons (dhobies) who washed them. The parts usually attacked are the groins, the upper part of the thighs and the armpits. The condition is due to a fungus like that of ringworm and the skin becomes red and raised and somewhat scurfy. Dhobie itch causes great irritation and is sometimes associated with considerable pain.
Treatment.—Mild cases are best treated by using an ointment containing resorcin two drachms, salicylic acid ten grains, and vaseline and lanoline, of each four drachms. The parts may be painted with iodine but this is somewhat irritating. An ointment of ammoniated mercury, two to five per cent., is often effective. Bad cases require the application of araroba (chrysarobin) ointment, but it should not be used unless recommended by a doctor. Goulard water or Wright’s liquor carbonis detergens (one tablespoonful to two pints of water) are soothing applications.
(2) There is a fungus disease of the hairs, especially of the armpits and the pubis, which occurs in tropical climates and is often very troublesome. The hairs assume a coated, beaded or nodular appearance and the deposit on them varies in colour and may be black, yellow or red. The underclothing in contact with the affected parts becomes stained and when the disease spreads to the skin, as it often does, the latter becomes inflamed, thickened and painful.
Prophylaxis.—Keep the axillae shaved. It is always well to do so in a tropical climate. Failing this, dust with a mixture of powdered sulphur and fuller’s earth, equal parts. Change the underclothing frequently and bathe the parts liable to infection.
Treatment.—Apply twice daily a lotion containing one drachm of formalin in six ounces of rectified spirit, and at night rub in a two per cent. sulphur ointment. If these measures fail apply tincture of iodine, except in cases where the skin is involved. In such cases bathe with cold water and employ a dusting powder or a soothing lotion.
(3) Ringworm of the head is a disease due to a fungus. The part for some distance round the affected area should be shaved, and any stumps of hairs pulled out. The skin should be lightly painted with tincture of iodine or strong solution of carbolic acid (one in ten of water); or sulphur, white precipitate, or mercurial ointment may be gently rubbed in.
Kraw-Kraw.—This is a term commonly employed by natives of the West Coast of Africa to indicate almost any kind of itchy, papular, or pustular eruption. Many of these appear to be contagious, and most of them are best treated by opening up any pustules which may be present, removing crusts by boric poultices, and scraping ulcers. Then scrub thoroughly with sublimate lotion 1 in 1,000, dust with boric powder and apply a dressing of medicated vaseline. The application should not be disturbed for a week when, as a rule, the skin will be found to have healed up. Clothing and any other articles which have been in contact with the affected parts should be destroyed or thoroughly disinfected.
Prickly Heat.—This condition is very frequent, especially in the moist tropics. It is due to free sweating, and is accompanied by intense heat and itching. The parts closely covered by clothing are specially apt to be affected. The skin becomes covered with numerous slightly inflamed papules, set close together, and the eruption may remain for months at a time, varying in intensity according to circumstances.