Hookworm Disease : Clinical Aspects

HOOKWORM DISEASE : CLINICAL ASPECTS

MANIFESTATIONS

In the overwhelming majority of infected patients, the worm burden is small and the infection asymptomatic. Clinical manifestations, when they do occur, may be related to the origi-nal penetration of the skin by the filariform larva, the migration of the larva through the lung, and/or the presence of the adult worm in the gut. Skin penetration may produce a pru-ritic erythematous rash and swelling, popularly known as ground itch. This manifestation is more common in infection with N. americanus, generally occurs between the toes, and may persist for several days. It is probably the result of prior sensitization to larval antigens.

 Pulmonary manifestations may mimic those seen in ascariasis, but are generally less frequent and less severe. In the gut, the adult worm may produce epigastric pain and ab-normal peristalsis. The major manifestations, however — anemia and hypoalbuminemia — are the result of chronic blood loss. The severity of the anemia depends on the worm bur-den and intake of dietary iron. If iron intake exceeds iron loss resulting from hookworm infection, a normal hematocrit will be maintained. Commonly, however, dietary iron is in-gested in a form that is poorly absorbed. As a result, severe anemia may develop over a pe-riod of months or years. In children, this condition may often precipitate heart failure or kwashiorkor. Mental, sexual, and physical development may be retarded.

DIAGNOSIS

The diagnosis is made by examining direct or concentrated stool for the distinctive eggs. As they are nearly identical in the two species, precise identification of the causative worm is generally not attempted. Quantitative egg counts can permit accurate estimation of worm load. If the stool is allowed to stand too long before it is examined, the eggs may hatch, releasing rhabditiform larvae. These larvae closely resemble those of S. stercoralis and must be differentiated from them.

TREATMENT AND PREVENTION

The anemia must be corrected. When it is mild or moderate, iron replacement is adequate. More severe anemia may require blood transfusions. The three most widely used anthelmintic agents, pyrantel pamoate, mebendazole and albendazole, are all highly ef-fective. Prevention requires improved sanitation.