Ancylostomiasis overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Kalpana Giri, MBBS[2]
Overview
Ancylostomiasis was first discovered by Dubini, an Italian physician, in 1838 who provided the first detailed description of hookworms during an autopsy on a woman who had died in Milan.
Historical Perspective
Ancylostomiasis was first discovered by Dubini, an Italian physician, in 1838 who provided the first detailed description of hookworms during an autopsy on a woman who had died in Milan. Necator americanus and Ancylostoma duodenale were responsible for all human hookworm infections mentioned by Bethony et al ( 2006), de Silva et al.(2003), however Bradbury & Traub (2016) and Traub et al. (2008) mentioned Ancylostoma ceylanicum is also an important hookworm of humans, especially in South East Asia.
Classification
Ancylostomiasis may be classified according to the species into two groups: Human hookworm: Ancylostoma and Necator Americanus and Zoonotic hookworm: Ancylostoma braziliense, Ancylostoma caninum, Ancylostoma ceylanicum and Uncinaria stenocephala.
pathophysiology
Ancylostomiasis is a hookworm infection, soil-transmitted helminths (STH) also known as miner's anaemia, tunnel disease, brickmaker's anaemia occurs predominantly in countries with low socioeconomic status located in tropical and subtropical areas of the world. The external surface of Helminth comprises key molecules excretory/secretory (ES) products which contain a large range of structurally and functionally distinct molecules, mostly proteins, and also lipids, and carbohydrates. These molecules also have major functions in the development and survival of parasites. By inhibiting the inflammatory reaction, encouraging effector cells apoptosis, and skewing the immune reaction phenotype, these molecules help the parasite to survive and evade the host immunological response. The biological role and molecular nature of hookworm ES products are still unclear though the intensive study has been done for many years. The life cycle of hookworm include: human hookworm and zoonotic hookworm. Mature females released eggs in the host’s small intestine and these eggs are passed in the feces, where they hatch first stage rhabditiform larva (L1) within several days. The L1 feeds on soil microbes and molts to the L2 stage, and under appropriate conditions, each eggs hatch in warm, moist, sandy soil, or in feces and develops into an infective filariform (L3) stage larva. The infective-stage larvae (L3) enter the body either through a cutaneous route or by direct oral ingestion. Human hookworm such as Ancylostoma and Necator Americanus enter the body by skin penetration which may cause a local pruritic dermatitis, also called ground itch at the site of penetration whereas the ancylostoma species can also enter the body orally. The infective larvae (L3) migrate through the dermis, enters the bloodstream, and reach the lungs and migrate across the alveoli. Then they ascend from the bronchial tree to the pharynx and reach the small intestine where they mount into fourth-stage larvae and mature into blood-feeding adults male or female. These adult worms release hyaluronidase and other hydrolytic enzymes result in blood extravasation by degrading the intestinal mucosa and erosion of blood vessels. Hookworms also secrete Ancylostoma ceylanicum anticoagulant peptide-1, which inhibits the blood coagulation in the attachment site and leads to blood loss from the intestine. Zoonotic hookworm (i.e., cat and dog hookworms) include: Ancylostoma braziliense, Ancylostoma caninum, Ancylostoma ceylanicum and Uncinaria stenocephala. Among these most commonly encountered hookwormis Ancylostoma braziliense. It causes cutaneous larva migrans (creeping eruption) generated by the larva migrating through the epidermis characterized by the erythematous serpiginous lesions. Ancylostoma ceylanicum is the only species that develops to adult in humans, and causes enteric hookworm infection. Ancylostoma caninum occasionally reaches adulthood in humans, and causes eosinophilic enteritis.
Causes
Common causes of Ancylostomiasis include: Ancylostoma duodenale, Necator americanus, Ancylostoma ceylanicum, and less common organisms include: Ancylostoma braziliense, Ancylostoma caninum, Ancylostoma ceylanicum, and Uncinaria stenocephala.
Differentiating ancylostomiasis from Other Diseases
Ancylostomiasis manifests in a variety of clinical forms, differentiation must be established in accordance with the particular sign and symptoms. Such as abdominal symptoms differentiated from ascariasis and trichuriasis, and parasites associated with pneumonitis and peripheral eosinophilia are Aascaris and Strongyloides species. Cutaneous manifestations are differentiated from contact dermatitis, scabies infection, migratory myiasis, and cercarial dermatitis. In infants gastrointestinal bleeding must be differentiated from other diseases that cause melena, pallor, anorexia, listlessness, and edema such as portal hypertension, Meckel’s diverticulum, or AV malformation. In adults gastrointestinal bleeding must be differentiated from other diseases such as Meckel’s diverticulum and Dieulafoy’s lesions, inflammatory bowel disease and nonsteroidal anti-inflammatory drug-induced small bowel disease. In older patient (>50 years old) are prone to gastrointestinal bleeding from angiectasias, adenocarcinoma, leiomyoma, and lymphoma.