Helminthiasis

Helminthiasis denotes infection by helminths, including nematodes (roundworms), cestodes (tapeworms), and trematodes (flukes). Globally, it is a major cause of morbidity in tropical and subtropical regions, though sporadic cases occur elsewhere.

Transmission occurs via ingestion of eggs or larvae in contaminated food or water; skin penetration by larvae; or consumption of undercooked or raw intermediate hosts. Life cycles often involve one or more intermediate hosts and can be simple or complex.

Clinical manifestations vary by species and site. Intestinal infections commonly cause abdominal pain, diarrhea, weight loss, and sometimes obstruction. Blood flukes and tissue nematodes may cause eosinophilia, anemia, hepatosplenomegaly, pulmonary symptoms, or CNS involvement. Chronic infection can lead to growth deficits in children and malnutrition.

Diagnosis relies on stool or urine examination for eggs or larvae, serology, imaging, and, in some cases, endoscopy or tissue biopsy.

Treatment depends on the pathogen. Anthelmintics include albendazole or mebendazole for many nematodes, praziquantel for cestodes and trematodes, and ivermectin for certain filarial infections. Resistance and drug choice depend on species and population.

Prevention includes improved sanitation, safe water, proper hand hygiene, cooking meat and fish thoroughly, and control programs such as mass drug administration in endemic areas. Surveillance and prompt treatment reduce transmission and disease burden.