Intestinal Parasites

Animal parasites are commonly found in the human intestine, more of­ten in children than in adults. Though especially common in countries with warm climates, this problem is not limited to such parts of the world. The parasites secure their food from the contents of the intestine in which they live, or from their victim's blood, which they usually obtain by attaching them­selves to the intestinal wall. Most of them are either protozoans, round­worms, or tapeworms, though at least one of some importance is a fluke. Some of them are harmless, or at the worst do very little damage; others cause disease or distress; and a few are a grave menace to life, though usually not until the passage of considerable time.

Fluke or Trematode Infections
There are many flukes that can in­fect the human body but only one that spends any considerable time in the intestine. The disease which it causes is called fasciolopsiasis, and the name of the fluke is Fasciolopsis buski. The eggs of this fluke are passed out in the feces. They hatch out in water. Their first stage of development takes place in the bodies of snails. Then the par­tially developed parasites encyst upon water plants most commonly caltrops, water chestnuts, or water hyacinths. If these are eaten raw, the parasites mature in the eater's intestine. They usually attach themselves to the lining of the duodenum or the jejunum, caus­ing inflammation and sometimes ulcer­ation and bleeding. Diarrhea and ab­dominal pain are common. Later the stools become greenish-yellow and contain much undigested food. In se­vere infections, there is likely to be fluid in the abdomen, nausea, vomit­ing, and edema of the face, abdominal wall, and the lower extremities. These symptoms are suggestive that the in­fection is present, and would be mean­ingful if the person concerned had been eating any of the indicated foods; but a definite diagnosis depends upon finding the eggs in the stools. Death rarely results from the disease itself, except in children; but the victim is likely to become so weakened by it that some other disease easily over­comes him.

This disease is rare in the Western Hemisphere, but it is fairly common in the Orient.

What to Do
1. If the disease is suspected, have a stool examination to find the eggs of the parasite.
2. When the disease is known to be present, its treatment should preferably be supervised by a physician. The accepted remedy is hexylres­orcinol, available in 100-milligram pills. Recommended dosage for re­spective age groups is as follows:

Under six years of age, 1 pill for each year of age.
6 to 8 years of age, 6 pills.
8 to 12 years of age, 8 pills. Adults and children over 12, 10 pills.

The evening before the drug is given, the patient should have a light supper and before retiring should take 1 tablespoonful of so­dium sulfate in a half glass of water as a laxative. The next morning, the correct dose of hexylresorcinol should be taken on an empty stom­ach. Two hours after the pills are taken, another tablespoonful of so­dium sulfate in a half glass of water should be taken. This completes one course of treatment. A second course, and perhaps a third course, of treatment is usually necessary, at four-day intervals.
3. As a preventive measure avoid eating raw caltrops, water chestnuts, or any other roots, plants, or "nuts" that might have Fasciolopsis buski cysts attached to them.

Protozoal Infections
Different kinds of protozoans may be found in the human intestine; but only two of them are important causes of disease. These are Endamoeba his­tolytica and Balantidium coli. Diseases caused by the former are much more common in warm climates than else­where, but it is not unusual to find cases in the United States and other countries in temperate zones. Most of these, however, are in people who have picked up their infection while. living or traveling in tropical or sub­tropical regions or in areas where sani­tation is poor.

AMEBIC DYSENTERY (AMEBIASIS).
Amebiasis, or infection with End-amoeba histolytica, is far more common than most people realize. Many are infected with this parasite without knowing it or being made noticeably ill by it. The parasite apparently al­ways gains entrance to the body through the digestive tract, being car­ried in by contaminated foods or bev­erages.

When the parasites produce severe intestinal disease, the victim has diar­rhea, cramps, and colicky pains; but these symptoms usually come on grad­ually rather than with a sudden onset. The stools contain pus, mucus, and blood, and may number twenty or more in a single day. Occasionally fe­ver and a rapid pulse are present. In a majority of cases the diarrhea and other symptoms are mild, but more or less chronic, and tend to alternate be­tween better and worse by spells. In some cases there may be only repeated spells of abdominal colic, with no diar­rhea at all. The true nature of the con­dition can be proved, however, by find­ing the active amoebas or their cysts in the stools; and it is wise to suspect any case of recurring or chronic diarrhea as being amebic dysentery until proved otherwise, especially in warm climates.

Anybody infected with Endamoeba histolytica should have thorough and persistent treatment to rid his body of the parasites. A severe case may prove fatal. Even a mild infection one so mild as to go unnoticed because of no definite intestinal symptoms may cause a general impairment of health. Ar­thritic pains may be caused by a mixed infection with shigella organisms. Ab­scess of the liver is an occasional com­plication of amebiasis, but an amebic liver abscess may develop without there having been any previous detectable intestinal symptoms. The organisms are carried from the intestine to the liver through the portal circulation. As a rule, only one such liver abscess is present in a given case, but there may be more than one.

All of the effective remedies for ame­biasis yet discovered are drugs that may harm the body if given improperly or in too large quantities. Emetine hy­drochloride, carbarsone, vioform, ter­ramycin and certain other antibiotics, and several other remedies have been used with good results; but they should be given only under the supervision of a physician. The treatment should be continued not only until all symptoms have been brought under control, but until the organisms can no longer be found in the stools.

Prevention of infection is obviously important, and this includes preven­tion of the spread of infection from a known case to other people. The fol­lowing preventive measures are recom­mended:

1. Protect all food, water, and other beverages from any chance of fecal or sewage contamination.
2. Carefully dispose of all human excreta.
3. Kill all flies, as far as possible, and take all practicable measures to pre­vent their breeding. All garbage should be kept in leakproof, covered containers. All animal fertilizer should be spread thinly on the ground or kept in tightly covered bins. All toilets or latrines should be carefully screened.
4. People living in places without fully adequate water sanitation should boil all drinking water, and after boil­ing store it in covered containers to prevent contamination.
5. Wherever human excreta are used to fertilize the soil, no vegetables or fruits should be eaten raw unless disin­fected as recommended by local pub­lic-health officials.
6. Food handlers should give care­fuI attention to their personal habits.
Fingernails should be kept trimmed and clean. Hands should always be washed with soap and water after def­ecation, and again immediately before beginning to handle food.
7. Before employing any person as a cook or other food handler, have his stools examined for the possible pres­ence of amoebas or their cysts. Many people are unknowingly carrying these organisms. People who continue to be food handlers in areas where amebic dysentery is known to occur should have annual stool examinations.

What to Do
1. If amebic infection is suspected, have a stool examination made to detect the presence of the causative
organisms.
2. If the infection is found to be present, the infected person should stay under the supervision of a physician, since no home treatment or remedy is effective.
3. Have the victim's stools reex­amined weekly until recovery seems to be complete, and yearly thereaf­ter, since there is always consider­able danger of relapse.
BACILLARY DYSENTERY.
BALANTIDIAL DYSENTERY (BALANTIDIASIS).
Balantidial dysentery is in many re­spects similar to amebic dysentery, but less common and less severe, though more widespread geographically. A large proportion of the infected indi­viduals are apparently healthy carriers of the parasite Balantidium coli and are never made ill by it. This is a com­mon parasite of swine, and the infec­tion is considerably more common among people who have contact with these animals than among people who do not. Liver abscesses are not pro­duced as a complication of this infection, as is the case with amebiasis. Of the remedies that have proved valu­able in cases of amebiasis, carbarsone is more effective than any of the others for balantidiasis; but some of the tetra­cycline antibiotics that have little or no effect on amoebas are of definite value against balantidia. For these reasons, the treatment of balantidiasis is less difficult than that for amebiasis.

What to Do
1. Follow the advice given under Amebic Dysentery.
2. Follow-up stool examinations are recommended, preferably yearly.
Roundworm Infections

COMMON ROUNDWORM INFECTION (ASCARIASIS)
Common roundworm infection is most prevalent in places with a warm, moist climate, but no part of the world is free from it. The worm is from six to fourteen inches (15 to 35 cm.) long, the female being larger than the male. It lives chiefly in the upper part of the small intestine, but may travel to other parts of the digestive tract. It may en­ter the stomach and be vomited up, or may find its way up into the throat, sometimes getting into the windpipe and the air passages, where it may cause strangulation or other serious injury. Only one or two may be pres­ent in the intestine, or possibly many.

The females produce large numbers of eggs, readily recognizable with the aid of a microscope. Several weeks' time is required for the embryo worms to develop in the eggs before they can infect humans. The eggs abound in places contaminated with fecal mate­rial. Children playing in contaminated dirt around houses or in gardens get the eggs on their hands, especially un­der their fingernails. Handling dogs or cats, or other pets that run about in contaminated places, may have the same result. Then when one eats with unwashed hands or uncleaned finger­nails, or puts the fingers into the mouth, the eggs get into the mouth and go down to the stomach and into the intestine, where they hatch, liber­ating the tiny embryos. The embryos then burrow into the intestinal walls and migrate through the tissues to the lungs, from there making their way back to the intestine in much the same way that hookworm larvae do. In the intestine, the embryo worms develop into adults and live for a considerable period of time.
During the migration of the imma­ture worms through the lungs, symp­toms similar to those caused by the migration of hookworm larvae may be caused if the numbers of the parasites are considerable. The presence of these forms in the intestines, of chil­dren especially, may give rise to ab­dominal pain, fever, diarrhea, grinding of the teeth, restlessness, and some­times convulsions; or their presence, especially if they are few in number, may cause no recognizable symptoms and may not even be suspected unless one of the worms is passed in the stool or unless a chance stool examination reveals the eggs. In regions known to be contaminated .periodic examinations of the stools of children are recom­mended.

What to Do
1. The diagnosis of common roundworm infection should be con­firmed by a laboratory examination of the stool specimen.
2. If a physician is available, ar­range for him to order and supervise the treatment. Several effective rem­edies are now available, and it is best for the physician to choose the one best suited to the individual case.
3. At the time of writing, the remedy which is generally favored for the treatment of roundworm in­fection is piperazine. The dosage depends on the weight of the pa­tient .
4. One month after the course of treatment, another stool examina­tion should be made to determine whether the worm eggs are still present. If so, another course of treatment should be given.

HOOKWORM INFECTION (ANCYLOSTOMIASIS).
Hookworms cause more cases of se­rious illness than do any other of the intestinal parasites. In many parts of the world, including some sections of the United States, hookworm disease is present in a considerable proportion of the population. In such localities, the average health and vigor of the people are below normal, their mental as well as physical efficiency being impaired.


Hookworms are small and slender, about half an inch (8 to 13 mm.) in length, the female being somewhat longer than the male. They live in the small intestine, where they attach themselves to the intestinal lining by means of their hooked mouths; and they feed by puncturing the blood ves­sels with their sharp teeth.

The female worms produce great numbers of eggs, which the human host expells with his stools and these hatch out after leaving the body. Con­tact with warm, moist soil favors the hatching of these eggs and the rapid development of the young embryos. When a skin surface, such as bare feet or hands, comes in contact with the moist earth containing these young worms, so small that they can scarcely be seen without a microscope, they rapidly penetrate the skin and enter the blood vessels. They are then carried by the blood to the lungs.

From the lungs the young book­worms gain entrance to the air pas­sages, make their way to the throat, and are then swallowed. In this round­about way they finally reach the intestine, where they develop into full‑grown worms. If fewer than a hundred worms are present, symptoms are not likely to be noticeable. But the pres­ence of five hundred or more will cause typical symptoms. In some of the most severe cases more than four thousand worms have been found in a single individual.

The only way to be sure that a per­son is infected with hookworms is to find the eggs or the worms themselves in his bowel discharges, but in most cases there are characteristic signs and symptoms. The soiling of the skin of the hands or feet with contaminated earth, and the resulting penetration of the minute worms through the skin, cause itching and burning of the af­fected skin, followed by the formation of small papules and blisters, and later by crusting. This condition, commonly called ground itch, is also known as miner's itch, foot itch, toe itch, dew itch, or water itch. During the time when the immature parasites are pass­ing through the lungs, there may be spells of coughing, with sore throat and bloody sputum.

While the parasites are attaching themselves to the intestinal wall and growing to maturity, the characteristic symptoms are diarrhea, flatulence, and abdominal discomfort. Later, weak­ness, pallor, fatigability, weight loss, anemia, and difficulty of breathing be­come common. The symptoms are particularly noticeable in growing chil­dren in whom a definite slowing of mental development and body growth occurs. Many people with hookworm disease have the habit of eating clay, chalk, or other abnormal substances. In some cases, especially where the num­ber of worms is large, there may be swelling of the feet or of the entire body, and an accumulation of fluid in the abdominal cavity. In time the anemia may become very severe, the hemoglobin of the blood sometimes be­ing as low as 10 percent of the normal amount. A person with such sever symptoms cannot live long unless tb worms are expelled.

The problem of preventing hookworm disease is one of great importance. Infected people must be helpe to expel the worms from their intestines, and then be taught how to pry vent further infection. Keeping tr hands out of the soil and the wearing of shoes by people working in hookworm areas would help; but it is c prime importance to make safe disposal of all human bowel discharges E the ground is not contaminated b them. Modern flush toilets or proper] designed and constructed privies, used as the sole depositories of fecal matter, would go far toward stamping out hookworm disease.

As a conclusion to the general discussion of hookworm infection, mention should be made of a peculiar condition called Larva migrans (creeping eruption) . This is caused by the larva of the dog and cat hookworm, which penetrate the human skin and migrate from place to place in it, usually wit] out going deeper or traveling moi than a few inches. The migration causes intense itching and a reddis eruption in the form of narrow crooked, slightly elevated ridges. TI eruption tends to persist for sever months, but the migrating larvae finalIy die and are absorbed by the ti sues. If they are numerous enough be very troublesome, and especially they are located near the skin surface as is often true, a physician may u special methods to kill them. If th penetrate deeper, as sometimes h, pens, nothing can be done except give symptomatic treatment while w, ing for them to die.

What to Do
1. Tetrachloroethylene is among the most effective remedies, but i dangerous to give it to alcoholic patients or to those with gastrointesti­nal disorders, severe constipation, any marked degree of anemia, or liver disease. It is difficult to be sure that none of the conditions warned against is present without tests and studies by a physician, and a physician should supervise the use of the drug. The physician may prefer some other remedy.
2. If no physician is available, pi­perazine may be used, administering it in the same way as recommended for a case of "Ascariasis."

PINWORM INFECTION (SEAT WORM INFECTION, OXYURIASIS, ENTEROBIASIS).
Pinworms live in the large intestine, especially in the rectum. They are usually present in large numbers, and f e-males ready to lay eggs often crawl out through the anus and lay their eggs upon the surrounding skin. They cause much itching in this region, especially at night.
These worms are white in color and small in size. The female, much larger than the male, averages less than half an inch (8 to 13 mm.) long. She lays large numbers of eggs, and there is danger of the infection's being carried to other people, or of the child's rein­fecting himself, through scratching about the itching anal region and later handling food or objects that he or other people will eat or handle, or by putting the fingers into the mouth. Un­derclothing and bedclothing easily be­come contaminated, and it has proved difficult to clear up the infection in one member of a family unless all the other members are treated at the same time.
When the eggs are swallowed, they 'hatch out in - the duodenum and mi- grate downward. If the skin around the anus is not kept clean, the eggs may hatch out there and the immature worms migrate back through the anus into the rectum. Pinworm infection does not cause severe symptoms, aside from the itching, as a rule; but there may be vague gastrointestinal discomfort, restlessness, and insomnia.

What to Do
1. If a physician is available, ar­range for him to order and supervise the treatment.
2. One of the preferred drugs for the treatment of pinworm infection is piperazine. Tablets of piperazine citrate or piperazine phosphate are usually available in either the 250 milligram or the 500 milligram sizes.
3. For itching of the skin, apply 1 percent phenol in petrolatum or 1 percent yellow oxide of mercury ointment, as needed
4. Have any infected person wear tight-fitting shorts day and night, or use any other effective method to prevent him from scratching the anal region.
5. Change underclothing and bed linen daily, and use boiling as a part of the laundering procedure.
6. Scrub toilet seats with soap and water every day.
7. For greater safety, have all members of the family treated.
8. All members of the family should carefully wash their hands with soap and water after each bowel movement and before all meals; and their fingernails should be trimmed short and kept clean. They should all be warned to keep their fingers out of their mouths and not to scratch the skin in the anal region.

STRONGYLOIDIASIS (STRONGY­LOIDES STERCORALIS [THREAD-WORM] INFECTION)
Strongyloides stercoralis infection is common in tropical and subtropical areas in all parts of the world, includ­ing the southeastern part of the United States. The larvae of this parasite usu­ally enter the body and migrate through it in much the same way as do hookworm larvae. Some of them, however, may complete much of their development in the lungs or the air passages, giving rise to symptoms resembling those of bronchitis or bron­chopneumonia. Infection of the intes tines, which is the usual form, may produce no noticeable symptoms, though a watery diarrhea fairly often shows up, and occasional cases go on to ulceration.
The adult worms resemble hook­worms in general appearance, but they are smaller. They are found in greater numbers in the duodenum than in any other part of the intestine. The anemia which they may cause is much less severe than that from hookworm infec tion. The eggs do not pass out in the stools as do the eggs of hookwormE but hatch while still in the intestinE and usually then the larvae pass ou and contaminate the soil. Occasionall, a few of the larvae do not pass out o the intestine, but perforate its walls causing an unusually severe illness.

What to Do
1. Confirmation of the diagnosis of this infection depends, of course on the finding of eggs and larvae ii the feces.
2. If at all possible, the treatment should be under the direction of physician.
3. At the time of writing, the drug most satisfactory in the treatment of strongyloidiasis is dithiaza nine iodide. For an adult, this should be given by mouth in doses of 20+ milligrams taken three times a day for ten days.

TRICHINOSIS (TRICHINIASIS).
In contrast to other roundworms, trichinae live for only a comparatively short time in the intestines. Trichino­sis is contracted by eating raw or in­sufficiently cooked flesh of animals con­taining the parasites in a dormant form. Nearly always the contaminated meat is the flesh of swine, though in a considerable number of reported cases it was bear meat, and apparently in a few cases other kinds of meat that had simply been chopped on the same block used to chop pork.
When infected meat is eaten, the embryo worms are liberated in the stomach and the intestine, where, in about three days, they grow to full size, most of them becoming rather deeply embedded in the intestinal mu­cous membrane. They do not lay eggs that pass out of the intestine, but pro­duce great numbers of young worms, most of which burrow into the tissues and are carried throughout the body by the blood and lymph circulation. They finally become encysted and dor­mant in the muscle tissue as tiny coiled worms. They are not equally abun­dant in all muscles, but the diaphragm gets more than its proportionate share of them.
After infected meat is eaten, six or seven days are required for the full development of the first brood of young embryos, which are then ready to mi- grate in the body. The production of embryos continues for six weeks or longer. Bowel symptoms, such as dis-comfort and diarrhea, may occur at the time of the multiplication of the worms in the intestine, and other and quite different symptoms develop while the young worms are migrating. These symptoms may be such as to arouse a suspicion of typhoid fever or rheumatism. They may be so severe that death results in some cases. Fever, chills, and abdominal and muscle pains are common. There is much muscle ten­derness, with swelling of the muscles and the overlying skin during the pe- riod while the embryo worms are be­coming encysted. The small worms may lie dormant in the muscles as long as twenty years, but the symptoms of their presence largely disappear after the first few weeks or months.

Autopsy surgeons who have made a search for the encysted parasites in dead bodies have reported that in some parts of the world where pork consumption is high and where certain pork products are often eaten raw, more than 20 percent of the population is probably infected. The amount of illness caused by so much infection must be great. Many of the fevers, aches, and pains that people in such areas attribute to other causes are really due to their fondness for pork.
Of people with trichinosis severe enough to be recognized as such, prob- ably one in twenty will die because of the infection, so it must be considered a very serious matter. Once the infec­tion has taken place, there is no way to stop its progress, so prevention of in­fection is of vital importance. Those who do not eat flesh food, but especially pork, are safe; but others should remember that encysted trichinae em­bryos can be killed by thorough cook­ing of the meat containing them. It has also been proved that freezing the meat and keeping it frozen for several months will kill at least most of the parasites.

What to Do
1. If symptoms suspicious of trich­inosis appear within three or four days after a person has eaten meat that might have been infected, the stomach and bowels should be thoroughly cleaned out, taking Epsom salts purgatives and copious enemas
2. After the worms have begun to migrate through the tissues, no remedy or treatment can stop them; but a physician can use remedies that will at least partially relieve the symptoms.
3. Long-continued hot baths—temperature about 100° to 102 ° F (38° to 39° C.) may help to relieve muscle pains; but cold compresses to the head must be given at the same time to prevent fainting, and the baths should not be continued long enough to produce profuse sweating (See Volume 3, chapter 20.)
WHIPWORM INFECTION (TRICHURIASIS).
Whipworms are about one and a half to two inches (35 to 50 mm.) long They get their common name from their shape, looking like a whip with a slender lash and a thicker handle. The small end of the lash is the head of the worm. Sometimes as many as a thou­sand worms are found in a single indi­vidual's intestine. They live chiefly it the large intestine and rarely cause any symptoms. They produce large numbers of eggs of a characteristic appearance, being easily recognized under a microscope by a person who knows what they look like. The worms are usually detected by being passed in the- stools from time to time. If pres­ent in great numbers, which is seldom true, they may cause some intestinal distress, diarrhea, and flatulence.
Whipworm eggs pass out of the in­testine and hatch in the soil as a rule. They enter the body in larval form, but their manner of entry is similar to that of the eggs of the common round- worm.

What to Do
1. If whipworm infection is sus­pected, watch for the easily visible worms to be passed in the stools.
2. When a physician is available,. arrange for him to supervise the treatment.
3. Dithiazanine iodide is presently the favored drug for the treatment of trichuriasis. The course of treat­ment lasts five days. The total daily quota of the drug should be di­vided into two or three doses spaced through the day.

Tapeworm Infections
Ordinarily, a tapeworm has a dou­ble life history. The larva, after being hatched from the egg, is found in the flesh of some of the lower animals. Eating raw. or insufficiently cooked flesh containing the larvae transfers them into the digestive tract of man, where they develop into their mature form.

All tapeworms are long, flat, and thin, with segmented bodies. The head is small and has sucking discs or hooklets or both, by which means it holds onto the intestinal wall. The old segments gradually drop from the back end as new segments are formed near the head. The segments that drop off and escape with the bowel movements often contain great numbers of eggs. These may later chance to be eaten by some lower animal along with its food. In the stomach and intestines of this animal, the eggs hatch into larvae, which migrate into the muscles or other parts of the animal's body and become encysted or dormant there, not developing further until the infected flesh of the animal is eaten by a human being or some other suitable host.
The • varieties of tapeworms most commonly found in the human intes­tine are separately described below.

BEEF TAPEWORM (TAENIA SAGINATA).
The head of the beef tapeworm has no hooklets. This may account for the comparative ease with which this worm is dislodged from its attachment to the intestinal wall when the proper remedy is used. Beef tapeworms may grow to a length of more than thirty feet (nearly 10 meters) .
Eggs pass out in great numbers in the victim's bowel movements, but even more of them are discharged in the segments of the worm, which are frequently broken off from the back end of the worm. These separate seg­ments seem to have an activity of their own, and often pass from the bowel at other times than when feces are passed.. Anybody acquainted with the characteristic appearance of . a tapeworm segment can easily tell the kind of worm from which it came.
The presence of the beef tapeworm sometimes causes diarrhea, hunger pains, and loss of weight. A greater than usual appetite may be the only noticeable symptom. All symptoms, however, are uncertain and are often absent. One can be sure of the para- site's presence only by discovering the segments of the worm as discharged from the bowel or by a miscroscopic examination of the stools to discover the tiny eggs.

DWARF TAPEWORM (HYMENOL­EPIS NANA).
This is the smallest of the tapeworms whose adult forms infect man. It lives in the small intestine, sometimes in small numbers, but there may be as many as a thousand in one intestine. Individual worms grow to be from one to one and a half inches (25 to 35 mm.) long. This worm is found more often in children than in grown people, and the eggs can hatch out and grow to maturity without leaving the intestine. Infection comes generally from swallowing the eggs rather than from eating flesh containing the larval worms. This tapeworm may produce nervous symptoms and loss of appetite, but often it causes no symptoms at all. When it is present, there are many eggs in the bowel movements. These have a characteristic appearance, and are easily recognized by a trained ob­server with a microscope.
With Hymenolepis nana should be classed the rat tapeworm, Hymenolepis diminuta, and the dog tapeworm, Dip­ylidium caninum, which also infects cats. Both of these latter two worms are comparatively small. They do not often infect human beings, but they seem to be transmitted most commonly by the accidental swallowing of worms or insects containing the larval forms. The last of the three has reddish segments shaped like melon seeds, and it is somewhat larger that the other two.

FISH TAPEWORM (DIPHYLLO­BOTHRIUM LATUM).
This is the largest of the tapeworms infecting man. It is not common in the United States. It may grow to a length of nearly forty feet ( more than 10 me­ters) . The segments may be half an inch (13mm.) broad, and one worm may have three thousand or more seg­ments. The egg of this worm must hatch out in the water, the larvae find entrance into the body of some fish, and the flesh of this fish be eaten by some person, if the person is to be in­fected with a fish tapeworm. Fresh­water fishes are most often infected. Salting or smoking the flesh of the fish does not kill the larvae, but thorough cooking does. In some cases the fish tapeworm causes an anemia similar to pernicious anemia. Its presence may give rise to hunger pains, diarrhea, ab- dominal distress, and loss of weight.

PORK TAPEWORM (TAENIA SOLIUM).
In the United States the pork tape­worm is less common than the beef tapeworm; but this is not true every­where. The muscles of the animal's body most often infected by the larvae are those of the neck, tongue, and shoulders. In many cases the infection produces no noticeable symptoms; but in some the infected person has diges­tive disturbances, hunger pains, and diarrhea alternating with constipation.

The pork tapeworm is comparatively difficult to expel, and may require repeated treatments. It sometimes grows to a length of about twenty feet (about 6 meters ), and may live in the intestine for many years. In some cases people become infected with the larval form of this tapeworm from accidentally swallowing its eggs, but the larvae do not stay in the intestine. They burrow through the walls of the intestine and may infect almost any part of the body, including the brain, where their presence may cause symptoms similar to those of epilepsy or of brain tumor.

What to Do
Quinacrine hydrocholoride (ata­brine) is the drug of choice. It is not recommended that it be used without a physician's supervision. A physician can arrange for proper safeguards and can best make the follow-up investigation needed to determine whether or not the treat­ment has been effective.

HYDATID DISEASE (ECHINOCOC­COSIS)
This is a tapeworm disease in one sense, but the adult worm does not in­fect the human intestine and the usual method of expelling the worm cannot be used, hence the discussion is kept separate from those concerning the worms that do infect the .intestine and that can be thus expelled.
Echinococcosis is common in many sheep-raising regions. The adult tape- worm, Echinococcus granulosus, usually infects the intestines of dogs, foxes, wolves, et cetera, which animals be­come infected by eating the carcasses of sheep containing the larval worms. Infection of humans is with the larval form, and usually results from swal­lowing food accidentally contaminated with dog feces or from handling dogs and then putting the fingers into the mouth.

When a person thus swallows the eggs, they hatch out in the intestine. The young worms spend but a short time there, and then burrow into the tissues. Most of those that survive lodge in the liver, where they cause the formation of cysts filled with fluid and lined with a membrane that may pro­duce large numbers of immature worm heads. Each of these heads could produce a mature worm if swallowed, but they would never be swallowed by any human under normal circum- stances. Some of these cysts act like malignant tumors, so hydatid disease may become a severe malady. If this disease is to be prevented, care must be used in handling sheep dogs and in disposing of sheep carcasses.

What to Do
1. No medicine or home treat­ment is of any use.
2. If a cyst grows large enough to cause symptoms, or if it ruptures, consult a physician. An operation may be beneficial.

Conclusion
In the whole range of the diseases of man it is in the field of intestinal para- sites that obedience to the rules of
cleanliness and the laws of sanitation proves most effective in preventing disease. Adequate provision for the disposal of all human excreta and the use of proper toilets should become universal. Human excreta should not be used for fertilizing fields or gardens —at least in any way that creates a dan­ger of contaminating food being grown for human consumption.

Neither children nor adults should go barefooted in places where the ground may be contaminated. They should keep their bodies clean, and wash their hands thoroughly after defecating, before eating, and before han­dling food. Care is necessary in associ­ation with domestic animals, including especially dogs and cats. Children run the greatest risk of infection, because of their natural carelessness and be­cause they come into such close con­tact with floors, the ground, and ani­mal pets. They should be provided with clean places in which to play, and they should be taught to keep their fingers and all other objects except proper food and drink out of their mouths.