This article describes the drugs used in helminthic
infections and their therapeutic indications, mode of action, toxicity and other details of each of the recommended drugs, and discusses the nature and treatment of
infection by helminths important in human medicine. Infestation due to the roundworms Enterobius vermicularis, Ascaris lumbricoides and the hookworms, Ancylostoma duodenale and Necator americanus can all be treated effectively with
pyrantel pamoate. For Enterobius vermicularis, however, a newer
drug,
mebendazole, is equally as effective. The advantage of these drugs in the indicated circumstances is that they can be administered in a single dose. Unfortunately,
pyrantel pamoate is not a panacea and in the case of Necator it is not as effective as in the other roundworms. In that situation the use of
tetrachlorethylene is preferable. For treatment of Strongyloides stercoralis, and important human parasite, because it can become disseminated and lead to fatal
infections in immunoincompetent hosts, the only effective
drug is
thiabendazole. In treatment of
Trichuris trichiura infection,
mebendazole, administered over a period of 3 days, is the most effective available
drug. For the roundworms inhabiting tissues--either as aberrant
infections of man or as the normal part of their life cycle in man--
therapy tends to be largely non-specific. For example, in
visceral larva migrans, caused by the dog roundworm Toxocara canis, only
palliative therapy with systemic
anti-inflammatory agents and
corticosteroids may be helpful.
Cutaneous larva migrans, caused by the dog hookworms Ancylostoma brasiliensis and Ancylostoma caninum, is also treated primarily with symptomatic measures, but there is a suggestion that
thiabendazole may kill the larvae and thus be effective. Trichinella spiralis may cause severe, even fatal
infections in man, but only symptomatic
therapy can be offered.
Therapy for filarial
infections is regrettably complicated and not completely effective.
Diethylcarbamazine remains the best available
drug, but in some of these
infections local surgical excision may also be used. It is important to bear in mind that release of
antigens from dying or dead worms may cause systemic inflammatory and
allergic reactions that may require
therapy with
corticosteroids.
Therapy for Cestodes is achieved most effectively with
niclosamide, but the
antimicrobial agent paromomycin has also been effective. For the aberrant
cestode infections of man, such as echinococcal
cysts or Taenia solium cycticerci, treatment is surgical if the affected areas are accessible. Treatment of schistosomal
infections is quite toxic and, therefore, it is mandatory to determine viability of the worms before recommending
therapy. If
therapy is required, then
Schistosoma mansoni infections are treated with
stibophen and S. japonicum with
antimony potassium tartrate, taking care in both of these instances to watch for the early signs of
antimony toxicity;
therapy of S. haematobium
infections is based on administration of
niridazole...