I.—Amœbic Dysentery

Amœbic dysentery, due to Entamœba histolytica (see pp. –41), is present throughout the tropical world and also occurs in temperate zones.

Walker and Sellards (1913) conducted important experiments with amœbæ on prisoners in the Philippine Islands. They showed experimentally that cultural amœbæ are non-pathogenic. As regards experiments with Entamœba coli, after feeding to twenty individuals they concluded that E. coli is a parasite of the human intestine but non-pathogenic and non-culturable. In a third series of experiments, after feeding with motile Entamœba histolytica, tetragena cysts were found in the stools later; when tetragena cysts were administered, motile E. histolytica were present in the subsequent stools. Some of the histolytica cases developed dysentery after a time. They lay stress on the necessity for the frequent examination of stools in order to detect carriers. The incubation period of entamœbic dysentery is usually long.

With regard to the symptomatology of amœbic dysentery, Castellani and Chalmers distinguish four types—the acute, chronic, latent, and mixed types.

The acute type has an abrupt onset; pain is felt in the lower part of the abdomen, and the motions, rarely exceeding thirty daily, are accompanied by much griping and straining. Blood and mucus are present in the motions, and occasionally greyish material, consisting of leucocytes, mucus, Charcot-Leyden crystals, amœbæ, and bacteria, sometimes with particles of tissue. Nausea and vomiting may occur. Digestion is usually deranged. The abdomen is sunken, the liver and spleen are normal, but tenderness is felt along the course of the large intestine. The urine may be diminished in quantity.

The chronic type may succeed the acute, or appear like diarrhœa, the motions being fæculent and containing mucus. Between exacerbations, constipation may occur. The number of motions may only be twelve to fourteen per diem. Gangrenous complications may occur at any time, and chronic dysentery may persist for many years.

The latent type is important, as the patients, though free from dysenteric symptoms, harbour amœbæ and act as parasite carriers. The latent condition may lead to acute attacks or to liver abscess.

The mixed type occurs where amœbic and bacillary dysentery are combined. There is much fever, nausea, and vomiting. The motions are numerous and often very offensive.

Treatment.—The most modern method of treatment, due to Leonard Rogers, is by emetine. According to Castellani and Chalmers, it is well to relieve griping and straining by either a hypodermic injection of morphia or by small enemata of 40 minims of laudanum in 1 oz. of mucilage of starch or by using 1/4 gr. morphia or 1/4 gr. codeine suppository. A dose of castor oil (ʒiv to ʒvi) with or without a few minims of liquor opii sedativus or a few doses of saline may be given during the first twenty-four hours. After the castor oil has acted or simultaneously, emetine treatment should be commenced; 1/3 to 1/2 gr. of emetine hydrochloride, dissolved in sterile normal salt solution, is injected hypodermically three times a day for two or three days.

If emetine cannot be obtained, 5 gr. doses of ipecacuanha every three to six hours in the form of membroids, or as pills coated with salol or keratin, can be substituted.

After acute symptoms have disappeared, intestinal irrigations once or twice daily, on alternate days, are useful. A solution of tannic acid (3 to 5 per 1,000) or of quinine bihydrochloride varying in strength from 1 in 5,000 to 1 in 750 is very slowly injected in quantities of 1/2 to 3 pints by means of a long, soft, rectal tube.

For gangrenous dysentery Castellani and Chalmers state that appendicostomy, with irrigation of the whole lower bowel with quinine lotion (1 in 1,000) or collargol (1 in 500), is the only chance.

The use of emetine should be continued in smaller doses after the dysenteric symptoms have ceased, in order to prevent relapses and as a possible safeguard against the development of a liver abscess.

Recently (July, 1914), Dr. W. E. Deeks has given an account of his successful procedure in dealing with the dysenteries in the Ancon Hospital, Panama Canal Zone, of which medical clinic he is the chief. With regard to amœbic dysentery he advocates: (1) Rest, to increase the patient’s resistance; (2) a generous milk diet, which is practically all absorbed before it reaches the large bowel; (3) saline or plain water irrigations, one to three daily; (4) the administration of bismuth sub-nitrate in heroic doses; 180 gr. is given mechanically suspended in about a tumbler of plain or effervescent water every three hours, day and night in severe cases, only lessening the amount when improvement takes place. Mechanical suspension in a large quantity of water is essential. When the stools begin to decrease in number and the tongue becomes clean, the number of doses is reduced to three or four daily. In very chronic cases one or two doses daily for a month after convalescence are recommended.

In exceptional cases of extreme emaciation and exhaustion, showing marked toxic symptoms, surgical treatment is necessary, and at Ancon a wide, open cæcostomy is performed.

The treatment of dysentery with bismuth sub-nitrate has been in use for some years at Ancon. Latterly, a combined treatment by hypodermic injections of emetine and bismuth sub-nitrate by the mouth has been used, and the authorities there consider that it is better to combine the two drugs rather than use each singly. Emetine probably acts as a direct poison to the amœbæ, while the bismuth probably acts by destroying the symbiotic organisms necessary for their growth.

With regard to preventive measures, all drinking water should be filtered and boiled, and uncooked vegetables and salads avoided. Scrupulous care with regard to personal cleanliness, and avoidance of touching the mouth or lips after contact with dysenteric patients, are essential. Isolation of parasite carriers is of great use in combating and controlling outbreaks of amœbic dysentery. The pollution of soil and water must be rigorously prevented.

Liver abscess due to amœbæ must be localized by exploratory punctures, and then opened and drained. Intramuscular injections of emetine hydrochloride, 1/6 gr. to 1/2 gr. every day, will reduce the temperature and afford relief.

Oral endamœbiasis has been recently investigated by Bass and Johns, Smith and Barrett and colleagues (see pp. , ). It responds to treatment with emetine, and 1/2 gr. of emetine hydrochloride administered hypodermically each day is of service. Rinsing the mouth with a solution of fluid extract of ipecacuanha is also useful.

Rogers (1915) recommends a combined treatment of emetine and streptococcal vaccines for pyorrhœa alveolaris.