War Surgery and Medicine
HUMAN ankylostomiasis is caused mainly by two species of blood-sucking nematodes—Ankylostoma duodenale and Necator americanus. Both are found on the mainland of Northern Australia, in New Guinea, and in most of the Pacific Islands. The nematodes attach themselves to the mucous membrane of the duodenum and jejunum and cause small haemorrhages. The eggs are passed in the faeces and develop as they are passed and in the soil, especially in hot, moist conditions, into filariform larvae. These infect man commonly by burrowing through the hair follicles of the skin of exposed parts, and sometimes by ingestion. When skin invasion occurs, the larvae travel by the blood to the lungs, then burst into the alveoli and so reach the oesophagus and alimentary canal. Eggs appear in the stools seven to ten weeks after skin infection.
The symptoms consist of (a) ground itch, generally seen in the feet, and less commonly in the arms, producing intense itchiness, redness, brawny swelling and a papular and vesicular eruption lasting two weeks; (b) upper abdominal symptoms; (c) anaemia. In mild cases no symptoms may arise before six months and then consist only of mild dyspepsia and fatigue. In severe cases symptoms may develop in ten to twenty weeks with marked fatigue and fainting attacks, and possibly some enlargement of the liver. The skin and nails may be dry, and oedema of the feet and ankles and puffiness of the face are common. Circulatory changes with rapid weak pulse and dilatation of the heart occur. The digestion is upset and constipation is the rule, with at times intermittent diarrhoea. The blood changes consist of an anaemia of hypochromic microcytic type, at times severe. Eosinophilia is the rule, ranging from 10 to 40 per cent, less marked in chronic cases.
Diagnosis is made either by routine stool examination, or by the detection of eosinophilia, or else by a history of ground itch, anaemia and dyspepsia.
Treatment consists in giving antihelminthic drugs. Three are commonly used: tetrachlorethylene, carbon tetrachloride, oil of chenapodium. The latter is commonly used in conjunction with either of the others. The drugs are given on an empty stomach, page 563 generally first thing in the morning, followed by a saline purge. Tetrachlorethylene is the least toxic, and no ill effects have been noticed in the free use of the drug, even in the forward areas. Anaemia is treated by giving a well-balanced and liberal high-protein diet and also iron in large doses.
Prophylaxis consists of the prevention of skin infection by wearing boots at all times, especially on river banks and the seashore, by camping only on clean ground, and by the protection of water and food supplies from contamination.