The Chigoe, commonly known as the jigger or sand-flea, is a minute parasitic insect, found in the West Indies and northern parts of South America. It is so small as to be scarcely visible; but the impregnated female possesses a proboscis, by means of which it penetrates the skin generally near the nails and there develops a bladder the size of a pea, which sets up severe inflammation. To get rid of the intruder, the orifice by which it entered must be dilated with a needle, until large enough to admit of its extraction, without rupturing the cyst.
Several species of Fleas infest the human frame. They are propagated by means of eggs, the worms from which enclose themselves in a tiny cocoon before assuming the adult form.
Three varieties of Lice occur on the human skin. The first (pediculus capitis) infests the head, especially of children, and multiplies with astonishing rapidity, the female laying altogether about fifty eggs. The other two varieties are the body louse (pediculus corporis) and the crab louse (pediculus pubis).
Strict attention to cleanliness is the best means of getting rid of fleas and bugs. A wash made of carbolic acid and vinegar painted over bed crevices is very efficient. Lice may be removed from the head by cutting the hair short, and carefully cutting out any hairs to which nits are attached. The nits are cemented to the shafts of hairs. Washing the hair with methylated spirit or paraffin is also helpful in removing them. Afterwards the use of white precipitate ointment will prevent their re-appearance.
The Trematoda or Flukes furnish two human parasites, viz. the liver-fluke (Distoma hepatis), and the Bilharzia hæmatobia. The liver-fluke occasionally produces jaundice in man. In sheep it is the cause of the disease known as the “rot.” The Bilharzia hœmatobia is chiefly found in Egypt, and the Cape Colony. It is about a quarter of an inch long, and infests the blood vessels, more particularly of the kidneys; setting up severe irritation and the discharge of blood. It is probable that the eggs of this parasite are received in drinking water or on salads, though occasionally inoculation may occur through the skin when bathing.
The family of Nematoda possesses numerous parasitic members. The common thread worm (Oxyuris Vermicularis) is one of the most common of these. The female is 1 ∕ 3 to ½ inch in length, and inhabits chiefly the lower bowel. The ova, which are from 1 ∕ 490 to 1 ∕ 1100 inch in diameter, often gain access to drinking water, or are carried by flies, or received on salads, etc. The injection of salt and water into the bowel, and treatment tending to improve the general health, are the proper remedies.
The round worm (Ascaris Lumbricoides) inhabits chiefly the small intestine; hence medicines for its removal require to be given by the mouth. The female is from 10 to 14 inches long; the ova, of which each female discharges on an average 160,000 daily, are from 1 ∕ 340 to 1 ∕ 440 inch in diameter.
The whip-worm (Trichocephalus Dispar) is a smaller nematode, which is rarely met with in this country. The Dochmius Duodenalis is met with chiefly in Italy and Egypt. It sucks the blood in the intestine, causing dangerous anæmia. The Strongylus Gigas is chiefly found in the kidneys of the ox, dog, etc., and is very rare in man. It resembles a very large round worm. In the kidney it produces severe disorders. How it gets there is not known.
The Trichina Spiralis has been already described (page [23]).
The Filaria Dracunculus (Guinea Worm) seems to gain access into the stomach along with water, or possibly in some cases, by perforating the skin. It burrows among the tissues, especially of the legs, and attains a length of several feet. It causes large boils and sores, and through these the eggs escape and pass into water. Here the embryo which has escaped from the egg meets with a fresh water crustacean (cyclops), enters its body, undergoes larval growth, and is swallowed with its host by a man, in whom it burrows and undergoes its next stage of life.