Hints to Travellers, Scientific and General, Vol. 2 / Tenth edition, revised and corrected

by Royal Geographical Society

There are other methods of treatment, but these can only be carried out under medical supervision.

The Hook Worm.—This is the American name for one or other of the species of ankylostomes which infect man. The disease they cause is known as ankylostomiasis, and it is common in many parts of the world, especially in the tropics. It chiefly affects natives, owing to their habits; but it occurs also in Europeans.

Cause.—Hook worms are small, almost cylindrical worms, which inhabit the human small intestine, to the wall of which they attach themselves by means of their mouths, which are furnished with formidable hooks and lancets. They suck blood, and the symptoms they produce are due in part to loss of blood, in part to the destruction of the lining membrane of the bowel, and possibly also in part to the effects of a poison which they are believed to excrete. Their eggs are passed in the excrement, and develop in the infected soil into larvæ, which are able to penetrate the unbroken skin if they come in contact with it. This is the most important route of infection, but it may occur also by means of infected drinking water and from contaminated food.

Symptoms.—The most marked feature of the disease is anæmia, which is often associated with digestive troubles. Palpitation of the heart and shortness of breath are frequently met with. In bad cases the appetite is disordered or depraved. The patient becomes pot-bellied, and there is swelling, chiefly about the face and ankles. The face is frequently puffy, and the skin assumes a peculiar earthy hue. It should be noted that a very early symptom is what is called ground itch. This is a skin eruption, usually on the feet and legs, due to the irritation caused by the larvæ penetrating the epidermis.

Prophylaxis.—The chief measure consists in preventing contamination of the soil by infected excrement. It is therefore important when camping to make proper provision in the way of latrines. Care must also be taken to prevent the fouling of water and food stuffs, such as vegetables, which are eaten uncooked. It is very dangerous to go about bare-foot in regions where the disease occurs, and camping sites should always be thoroughly cleansed.

Treatment.—Efficient treatment can only be carried out in association with microscopic examination of the stools, and hence all that need here be said is that various worm medicines are employed, of which the most effectual are thymol and oil of chenopodium. These should be administered only under careful medical supervision. The anæmia has to be treated, and in the case of natives a nutritious and easily-digested diet is indicated; for example, for native coolies the following has been recommended: bread 1 pound, milk 2 pints, sugar 2 ounces, 2 eggs, and 4 bananas daily. Ground itch should be treated by an ointment containing zinc oxide and salicylic acid.

The Bilharzia Worm.—This worm, of which there are two species, produces the disease known as Bilharziasis or Schistosomiasis, which occurs in one or other, or both forms, in various parts of the world, but is specially prevalent in Egypt.

Cause.—The worms, which produce either urinary or rectal bilharziasis, live in parts of the human vascular system, where they produce their eggs. These eggs are furnished with spines, and hence cause irritation when lodged in the tissues. In the urinary form the eggs have a terminal spine, in the intestinal form the spine is lateral. These eggs are passed either in the urine or in the excreta and reach water, where they develop into larvæ. The larvæ enter special species of water snails, in which they develop, producing eventually tiny forms known as cercariæ. These cercariæ escape into the water and can penetrate the unbroken skin or intact mucous membrane. They thus get access to the bodies of persons who are bathing in the infected water, or who may drink it. Once in the human body, the blood carries them to the place where they develop into the adult worms, which eventually unite, and then the females begin producing the spined eggs.

Symptoms.—In the urinary form the chief symptom is the passage of bloody urine, which usually shows itself about three months after infection, and is often associated with a good deal of irritation of the bladder and the pipe. The intestinal form may produce various symptoms. Sometimes a condition resembling enteric fever occurs, sometimes one like dysentery. Diarrhœa is common. The condition is chronic and, if untreated, sets up all kinds of secondary effects, which need not be discussed.