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Intestinal Nematodes 145

water and food and providing for safe disposal of human may require testing for occult blood, which is a condition
wastes will eliminate many of the cases. It is necessary to caused by broken down red blood cells that are not vis-
teach children to both avoid infection and reinfection. ible to the naked eye. It is possible to become infected
Changes in the lifestyle should be taught to the children with hookworms by direct contact with contaminated
that include hygienic practices and habits that are rein- soil, generally through walking barefoot, or accidentally
forced by the parents and others in authority, such as swallowing contaminated soil.
teachers. This is a practice that will stand them in good
stead for many years, and will help to avoid other parasitic
and bacterial infections such as pinworm as well as many ANCYLOSTOMA DUODENALE
infections. During treatment and following treatment, all AND NECATOR AMERICANUS
family members should adopt the practice of thoroughly
washing hands and cleaning fingernails thoroughly and Many individuals with hookworm infection have no
regularly with warm water and soap. After using the com- symptoms. The two major hookworm species, those of
mode, the seat of the commode should be sprayed with a Ancylostoma duodenale and Necator americanus, are
disinfectant to prevent eggs on the surface of the seat from similar in many ways. Therefore, they are treated jointly
coming in contact with the hands when a family member and comparatively in this section. Strongyloides stercora-
is infected. Food preparation should be started only after lis is another pathogen that must be differentiated from
careful washing of the hands. Keep finger nails short and the hookworms, A. duodenale and N. americanus.
clean, and avoid scratching the anus and genitals and nail
biting will prevent reinfection. Daily bathing and show- Morphology
ering are important, as well as washing bed linens and
nightwear with hot water and laundry detergent. The adult stages of A. duodenale and N. americanus are
seldom seen for identification, but they are similar in ap-
pearance. The eggs are indistinguishable as there is only
HOOKWORM INFECTION a slight difference in size between the two species. The
eggs of N. americanus are slightly larger than those of
It should be noted that a large number of nematodes A. duodenale and measure from 55 to 75 μm in length,
are capable of infecting humans. Another category of a with a width of between 35 and 40 μm. A.duodenale and
widespread nematode is the hookworm (refers to a number N. americanus also differ in their mouthparts or buccal
of species), which is also a roundworm and lives in the small cavities (Figure 6-6). The buccal capsule of A. duodenale
intestine of its host. Its eggs and worms are frequently found has visible teeth, whereas N. americanus has specialized
in the fecal specimens of those infected with hookworms structures called cutting plates.
(Figure 6-5). The two major species, Ancylostoma
duodenale and Necator americanus, range over broad areas Symptoms
of both the Old and the New World. These two species
are much smaller than the large roundworm called Ascaris The symptoms can be linked to inflammation of the
lumbricoides and include additional physical complications gastrointestinal system that is stimulated by feeding hook-
in the infected victim through migration into the body’s worms. Inflammation is accompanied by nausea, abdomi-
tissues. Obstruction of the gastrointestinal tract that may be nal pain, and intermittent diarrhea early in the course of
experienced with an A. lumbricoides roundworm infestation the disease, and a common consequence of hookworm
is less frequent in hookworm infestations. infections is that of progressive anemia that often occurs
The most significant risk from hookworm infection in prolonged infections. Patients with more severe infec-
is the development of anemia, which is caused by deple- tions may encounter the above symptoms as well as vomit-
tion of dietary iron, proteins, and iron supplements, that ing related to the nausea along with general fatigue. Old
are absorbed in the digestive tract. The worms extract home remedies were often followed in many areas of the
blood large amounts of blood and in addition may dam- world, particularly in the southeastern United States.
age the mucosa of the intestinal tract and cause blood to Impulsive or unreasonable appetite desires such as pica
appear in the feces. The blood loss through the stools (or dirt-eating), led to the practice in the southern states