CHAPTER XXIII

THE SCHISTOSOMIASES

GENERAL CONSIDERATIONS

There is a group of diseases, caused by trematodes of the family Schistosomidae, to which we apply the name schistosomiasis. The Schistosomidae differ from other human flukes (Trematoda) by not being hermaphroditic and by having nonoperculated eggs. From these eggs a ciliated embryo (miracidium) emerges which gains entrance to certain species of molluscs. In this intermediate host the miracidium gives rise to a sporocyst, which latter forms daughter sporocysts. These emerge from the mother cyst and enter the digestive gland of the mollusc and produce cercariae.

These cercariae show an absence of a pharynx and upon the rupturing of the sporocyst are discharged from the mollusc and furnish the infecting stage for penetrating the skin of man or other animal.

There are those who think the entrance is effected through mucous membranes, especially those of the mouth, genitalia and anus and even the nasal mucosa.

It is generally admitted that infection by drinking water, containing the ciliated embryos, is impossible, owing to the rapidity of their destruction by solutions of HCl of similar strength to that of the gastric juice.

Infecting mice with _S. japonicum_ cercariae from snails mashed on the abdominal surface of the mouse, it was found by Suyeyasu that after penetrating the skin the cercariae went to the right heart by way of venous and lymphatic channels. From the pulmonary vessels they penetrate the lungs and go by way of the mediastinum or pleura to the diaphragm which they penetrate and make their way to the abdominal cavity next penetrating the liver and entering the portal vein.

It is probable that the earlier stages of development take place in the portal vein and that having reached maturity the female attaches herself to the male and together they go, by way of the inferior mesenteric vein, to the haemorrhoidal or vesical terminals. The male is in the shape of a narrow leaf, about ½ inch long with a ventrally turned oral sucker and a closely adjacent ventral sucker. The female is a somewhat longer and cylindrical worm almost an inch in length and, like the male, has two suckers. There is a dark brown zig-zag stripe which shows prominently in the posterior part of the female and outlines the blood-filled intestinal tract. When the female applies herself to the ventral surface of the male there is an infolding of the sides of the flattened surface giving the male a cylindrical outline and resulting in the formation of a canal containing the female (gynaecophoric canal).

[Illustration: FIG. 106.—_Schistosoma japonicum_ (male and female). The sharp edges of the borders at the beginning of the gynaecophoric canal formed by the male are an accidental appearance. (From Mense.)]

The males of the flukes which cause the vesical (_Schistosoma haematobium_) and the rectal (_Schistosoma mansoni_) involvement are covered externally with small tubercles and have a ventral sucker only slightly larger than the oral one. The Japanese schistosome (_Schistosoma japonicum_) is slightly smaller, has a smooth surface and shows a prominent pedunculated ventral sucker of much larger size than the oral one.

Both suckers are larger than those of the other species.

The eggs of _S. haematobium_ have a terminal spine and measure from 115 to 175 by 60 microns; those of _S. mansoni_ have a lateral spine and measure from 110 to 125 by 50 microns while those of _S. japonicum_ are devoid of spinous projections and measure about 100 by 70 microns.

Clinically, the three infections differ as will be noted further on.

Looss claims that the two tuberculated species are identical and that the lateral spined egg is the product of an unfertilized female. He has more recently regarded the egg as produced parthenogenetically. Other helminthologists have noted slight anatomical differences as to ovaries and testicles so that the consensus of opinion is that vesical and rectal bilharziases are caused by different species of the genus _Schistosoma_.

[Illustration: FIG. 107.—Ovum of _Schistosoma japonicum_. By J. A. Thomson. (Jefferys and Maxwell.)]

Recently Leiper has found cercariae showing the absence of a pharynx (characteristic of the genus) in a Japanese mollusc. Such molluscs were teased out in water and laboratory bred mice immersed therein. One of these mice was killed a month later and adult schistosomes were found in the portal vessels. Leiper has also found cercariae showing absence of pharynx in four different species of molluscs in Egypt. With such molluscs he was able to infect white rats and other animals. He states that infection with these cercariae from the mollusc host can bring about infection either by way of the mouth or through the skin. Sodium bisulphate in a strength of 1 to 1000 killed these cercariae almost immediately.

It would therefore seem proven that all human schistosome infections take place following cercarial and not miracidial development. As proof that _S. haematobium_ and _S. mansoni_ are different species, Leiper notes that mice infected by molluscs of the genus _Bullinus_ showed schistosomes with terminal spined eggs, the ovary lying in the lower half of the female. The male had four or five large testes. In mice infected by molluscs of the genus _Planorbis_, the eggs were lateral spined, the ovary was in the anterior half of the body and the male had eight small testicles.

The mollusc host of _S. japonicum_ is _Blanfordia nosophora_. The shell of this snail is of cornucopia shape.

As these flukes are found in the blood vessels they are often referred to as the blood flukes.

HISTORY

Vesical schistosomiasis has undoubtedly existed in Egypt since ancient periods as vesical calculi are frequent in the mummies of various dynasties. Ruffer has found calcified schistosome ova in the kidney of a mummy.

The French troops suffered greatly from the disease in 1800. It was Bilharz in Cairo, in 1851, who first associated the haematuria with the presence of the parasite and it is from his name that we get the designation bilharziasis or bilharziosis for the disease.

In 1903, Manson found lateral spined eggs in a patient from the West Indies who was suffering from rectal rather than bladder symptoms. In 1907 Sambon, considering the points of difference between the eggs and the involvement of rectum rather than bladder, established a new species, _S. mansoni_.

In the West Indies, as shown by the reports of Surgeon Holcomb from Porto Rico, rectal bilharziasis is rather common.

For a number of years Japanese physicians had noted the existence of a disease characterized by splenic and hepatic enlargement, ascites and cachexia. In August, 1904, Katsurada discovered ova with a ciliated embryo in the stools of patients with this disease. He found schistosomes in the portal vessels of dogs and cats containing eggs similar to those seen in the human cases. He named this trematode _S. japonicum_. In November, 1904, Catto discovered the parasite at an autopsy on a Chinaman. In 1910 Lambert, in China, described a disease, which he called urticarial fever, and a short time afterward Houghton established the connection between this disease and the more advanced stages of Japanese schistosomiasis.

[Illustration: FIG. 108.—Ovum of _Schistosoma haematobium_. By William Pepper. (Jefferys and Maxwell.)]

[Illustration: FIG. 109.—Ovum of _Schistosoma mansoni_. By William Pepper. (Jefferys and Maxwell.)]

PATHOLOGY

The pathological lesions are almost entirely due to the irritation of the eggs with resulting connective tissue increase or ulcerative processes. For some reason these flukes select the inferior mesenteric vein and make their way to the vesical plexus of veins in the case of _S. haematobium_ and to the haemorrhoidal vessels for the other species. At times the ova or worms may be carried over to the systemic veins by way of the channels of anastomosis. In the terminal vessels the female gives off the eggs which penetrate the adjacent mucosa giving rise to inflammatory thickenings and the extrusion of the irritating eggs into the lumen of the bladder or rectum.

In the bladder these terminal spined eggs cause haematuria and form the nucleus for vesical calculi. The mucosa may also show wart-like excrescences. If the eggs are swept back through the portal vessels to the liver an interlobular cirrhosis results which would seem to be due entirely to the irritation of these egg emboli and not to toxic products of the worms themselves. Marked ureteral and kidney lesions may result as complications of cystitis or primarily from irritation by ova. In women the vagina, vulva and cervix uteri may show papillomatous thickenings. Bilharzial lesions of the male urethra are not uncommon and may lead to fibroid thickenings and fistula.

In searching for the flukes at autopsy we should make a longitudinal slit in the portal vein and with a spoon scoop out the blood and search for the parasites in a glass dish.

In the intestinal form of schistosomiasis the rectum may be studded with polypoid tumors which when projecting from the anus may ulcerate and lead to a diagnosis of cancer of the rectum. In sections from these masses great numbers of lateral spined eggs may be found.

The connective tissue increase is in the submucosa. The gut section may also present small abscess-like areas.

Eggs have been found in the appendix as well as in the large intestines and the small intestine has been found involved in one case. In rare instances ova have been found in the lungs, spleen and even in the brain and spinal cord.

By digesting selected tissues in 4% NaOH at 75°C. and centrifuging one may find eggs which otherwise would be overlooked. Statistics from Cairo usually note 30 to 40% of infection in natives but Ferguson employing all methods found 61% infected at autopsies on 600 males. In all forms of schistosomiasis but particularly in the Japanese infection, eosinophilia is pronounced.

In Japanese schistosomiasis the intestines may show thickenings at the site of aggregations of eggs. In the liver a marked interlobular cirrhosis occurs with numerous eggs in the connective tissue increase. Rarely, eggs may lodge in the brain, giving granuloma-like areas. The irritating eggs may also give rise to similar areas in the lungs.

SYMPTOMATOLOGY

Vesical Schistosomiasis or Endemic Haematuria

This form of the disease is chiefly found in Egypt, Syria, Uganda and South Africa. It is caused by _S. haematobium_ and the period of incubation is approximately six months.

[Illustration: FIG. 110.—Vesical schistosomiasis showing fistulous tracts opening from penis and scrotum. (From Ruge and zur Verth.)]

The first symptoms are pricking sensations about urethra and slight haematuria which comes on at the end of the act of micturition. Excesses or fatigue are apt to increase the haematuria. The diagnosis is made by finding the ova in the sediment of the centrifuged urine.

Symptoms of cystitis and even pyelitis may follow the early bladder and urethral manifestations. Pain in the back or symptoms suggesting renal colic may be present. Anaemia and physical weakness gradually develop. An important sequel is vesical calculus. It is a question whether the eggs or some other product of the infection form the nucleus of such a stone. Not only can stone be recognized by cystoscopy but rather distinctive are small, glazed yellowish nodules with areas of granulation tissue. Papillomatous growths may also be seen upon cystoscopy.

Perineal fistulae in the male and vaginitis in the female may be noted.

When reinfection does not occur the haematuria tends slowly to disappear but recovery does not usually take place for several years. The vesical schistosome (_S. haematobium_) often causes pathological changes in the rectum so that a case may show both vesical and rectal symptoms. The rectal schistosome (_S. mansoni_) does not give rise to vesical trouble.

Rectal Schistosomiasis

While terminal spined eggs may be found in rectal lesions, but usually combined with lateral spined eggs, in countries where the vesical form of the disease exists, yet there are many parts of the world where, with the exclusive existence of an intestinal bilharziasis, only lateral spined eggs are found. The infection resulting from _S. mansoni_ is the sole one in the West Indies, Congo Free State and in North-eastern South America.

The symptoms are usually those of a chronic dysentery with more or less tenesmus and straining. Prolapse is a common result and is the cause of the ulcerations which may cause the disease to be diagnosed as cancer. Cirrhosis of the liver is more apt to occur than in pure vesical schistosomiasis.

Most writers fail to mention other than the later manifestations of rectal bilharziasis, the earlier symptoms being overlooked or attributed to other causes. The same was true of Japanese schistosomiasis in which the initial “urticarial fever” was only recognized as connected with the late manifestations of liver cirrhosis and ascites a few years ago.

In 1916 Lawton noted in a number of Australian soldiers, encamped in Egypt, a fever of about 7 to 10 days’ duration in which the evening rise approximated 103°F. A diarrhoea and abdominal pain accompanied the fever and along with this a cough and patchy consolidation. Most of the cases showed urticaria which lasted from one to seven days. All cases showed a well marked eosinophilia. The diagnosis, but frequently only after prolonged and continued search, was made by the finding of the lateral spined eggs of _S. mansoni_. The period of incubation in these cases seemed to be from one to three months.

Japanese Schistosomiasis

This is also called Katayama disease and in its early stages urticarial fever or Yangtse fever. It is caused by the nontuberculated species, _S. japonicum_, which is characterized by the egg without a spine.

Laning, in a study of 7 well-controlled cases, has shown that the disease sets in after two or three days from the time of exposure to infection, by wading through paddy fields or still waters of infected ponds or lakes. The disease occurs in China, Japan and possibly in the Philippine Islands.

[Illustration: A B

FIG. 111.—A and B, Case of _Schistosoma japonicum_. Severe infection of three years’ duration. Ova very abundant in stools. Liver dullness diminished. Spleen not enlarged. (From Jefferys and Maxwell.)]

The course of the disease may be divided into 3 stages: the 1st, that of urticarial, pulmonary and febrile manifestations, which lasts about a month; the 2d, where ova begin to show in the small mass of bloody mucus which may cap the stool, and finally the 3d stage with cirrhosis of the liver, ascites, cachexia and death.

In the 1st stage we have headache and an evening rise of temperature to about 101°F. or 102°F. Shortly after the onset urticarial lesions, which may be 2 or 3 inches in diameter, may appear and disappear on various parts of the body.

The pulse rate is usually low. Very characteristic and early manifestations are those of the pulmonary involvement. Here oedematous patches may give the signs of crepitation and consolidation to rapidly disappear and reappear in another part of the lungs.

These pulmonary manifestations and the associated fever frequently cause a diagnosis of broncho-pneumonia to be made. A dry hacking cough appears early and with the fever, etc., may make one think of tuberculosis. The urticarial lesions often cause a diagnosis of ptomaine poisoning to be made. The blood examination shows a marked eosinophilia, of from 30 to 60%.

The 2d stage shows more or less intestinal disturbance with at times bloody mucus containing ova. The ova may not be present for long intervals or may never be found. Where reinfection does not take place the patient tends to recover but if exposure to infection be kept up then the 3d stage sets in with rather marked dysenteric manifestations, emaciation, anaemia, ascites, dropsy and a terminal cachexia.

The bladder never seems to be involved in Japanese schistosomiasis. The eggs, however may be carried to the brain and produce symptoms of Jacksonian epilepsy.

LABORATORY DIAGNOSIS

This consists in the search for ova in the centrifuged urine of vesical bilharziasis or in the bloody mucus of the intestinal manifestations of the disease. If one adds water to the urine the ciliated embryo will be noticed to break out of the shell in a few minutes and move about actively as if in search for some host.

The eosinophilia is of great diagnostic value and is usually associated with an increase in the leucocyte count.

Fairley has introduced a complement fixation reaction in diagnosis, using an extract of the livers of infected snails as antigen. The reaction appears early in the infection but disappears in the later stages. It is a group reaction as the livers of Bullinus answer for the _S. mansoni_ serum as well as for the specific _S. haematobium_ serum.

PROPHYLAXIS

Bathing should be allowed only in filtered water, there being an absence of the infecting cercariae in such a supply.

Then, too, if a water which does not contain fresh water snails is stored for three or four days the cercariae which might have been present in the freshly pumped up water will have died out, such free cercariae only surviving for about this period. The gastric juice will destroy cercariae so that it would seem impossible for an infection to occur by the alimentary tract atrium with the exception that cercariae might bore their way through the buccal mucosa as well as through the skin. The sterilization of the urine of cases of vesical bilharziasis and of the faeces in other forms should be carried out where practicable. It is now considered practicable to eradicate carriers of the infection with antimony treatment.

TREATMENT

The most important matter is to avoid places where the infection is known to exist. If one must wade through infected waters the body should be protected by canvas or other closely woven garments.

Of various treatments, having in view the destruction of the worm, such as salvarsan, etc., none seem to have been of any value except antimony.

Robertson has reported relief of symptoms from the administration of 2 grains of thymol dissolved in half a drachm of benzine. The treatment is continued for a few weeks. Others have not had good results from this treatment. Local treatment is necessary in treating the cystitis and prolapse of rectum. Operative procedures are indicated where calculi exist.

The results obtained by treatment with tartrate of antimony during the past three years justify us in considering bilharziasis as a disease which has a specific for its cure. Almost all cases will yield to a course of intravenous injections of from one-half to two grains of the drug, commencing with the smaller dose. The drug should be well diluted (25 to 50 cc. sterile saline). Some use a 1% solution but the higher dilutions are safer from a standpoint of avoiding phlebitis. Intravenous injections are made twice weekly and the total amount of drug given during the course should rarely exceed 25 to 30 grains. For details see under treatment of leishmaniasis.

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