Ancylostomiasis overview
|
Ancylostomiasis Microchapters |
|
Diagnosis |
|---|
|
Treatment |
|
Case Studies |
|
Ancylostomiasis overview On the Web |
|
American Roentgen Ray Society Images of Ancylostomiasis overview |
|
Risk calculators and risk factors for Ancylostomiasis overview |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Kalpana Giri, MBBS[2]
Overview
Ancylostomiasis was first discovered by Dubini, an Italian physician, in 1838. Ancylostomiasis may be classified according to the species into two groups: Human hookworm and Zoonotic hookworm. Ancylostomiasis is a hookworm infection, soil-transmitted helminths (STH) 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 distinct molecules, mostly proteins, and also lipids, and carbohydrates. These molecules help the parasite to survive and evade the host immunological response. 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). L1 feeds on soil microbes and molts to the L2 stage, and under appropriate conditions, 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. The infective larvae (L3) penetrate the skin, enters the bloodstream, and reach the lungs then it ascend to the pharynx and reach the small intestine where they mount into fourth-stage larvae and mature into blood-feeding adults male or female. Common causes of ancylostomiasis include: Ancylostoma duodenale, Necator americanus, Ancylostoma ceylanicum. The incidence rate is 7.5/100 person-years, prevalence is approximately 1 billion people worldwide, and mortality rate in the tropics is approximately 50-60,000 deaths per year. It commonly affects children and women of childbearing age. Common risk factors include: exposure to infected soil, poor sanitation, low socioeconomic status, low educational attainment. The most common complications include: Iron deficiency anemia, in child: intellectual and cognitive development, in pregnant women: severe anemia, impaired growth, severe anemia, premature birth, neonatal anemia. Prognosis is generally excellent with proper treatment. The diagnostic test is the microscopic detection of hookworms eggs in stool. Common symptoms include: anorexia, flatulence, diarrhea, weight loss, pallor, dyspnea, weakness, generalized edema, melena, hematemesis, dizziness, syncope. Lab findings include: decreased hemoglobin, eosinophilia, presence of several live and motile worms in upper gastrointestinal endoscopy. For treatment anti-helminthic therapies are recommended among patients with ancylostomiasis. Efficacy of treatment varies according to the severity of infection, geographical distribution, and age groups. Multiple blood transfusion, iron supplements are also be given in severe cases. Effective measures for the primary prevention of ancylostomiasis include periodic mass anthelminthic treatment of at-risk populations, avoid gardening barefooted, patient education on proper hygiene and sanitation.
Historical Perspective
Ancylostomiasis was first discovered by Dubini, an Italian physician, in 1838.
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) 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 distinct molecules, mostly proteins, and also lipids, and carbohydrates. These molecules help the parasite to survive and evade the host immunological response. 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). L1 feeds on soil microbes and molts to the L2 stage, and under appropriate conditions, 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. The infective larvae (L3) penetrate the skin and through the dermis, enters the bloodstream, and reach the lungs and ascend 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 degrades the intestinal mucosa and erosion of blood vessels which results in blood extravasation
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 must be differentiated from contact dermatitis, scabies infection, migratory myiasis, and cercarial dermatitis for cutaneous manifestations, and portal hypertension, meckel’s diverticulum, inflammatory bowel disease and nonsteroidal anti-inflammatory drug-induced small bowel disease, angiectasias, adenocarcinoma, leiomyoma, and lymphoma for GI bleeding.
Epidemiology and Demographics
The incidence rate of hookworm infection was 7.5/100 person-years. Prevalence of ancylostomiasis is approximately 1 billion people worldwide. People of all ages are susceptible to ancylostomiasis, commonly affects children and women of childbearing age. Mortality rate of hookworms in the tropics is approximately 50-60,000 deaths per year. Men are more commonly affected by ancylostomiasis than women.
Risk Factors
Common risk factors of ancylostomiasis include: exposure to soil where filariform larvae, the infective stage, live in and penetrate human skin, poor sanitation, low socioeconomic status, low educational attainment.
Natural History, Complications, and Prognosis
The majority of the infected patients remain asymptomatic. The symptoms of ancylostomiasis typically develop by direct contact of the skin with contaminated soil and the fecal-oral route. The most common complications include: Iron deficiency anemia, in child: intellectual and cognitive development, in pregnant women: severe anemia, impaired growth, severe anemia, premature birth, neonatal anemia. Prognosis is generally excellent with proper treatment.
Diagnosis
Diagnostic Study of Choice
The diagnostic test of ancylostomiasis is the microscopic detection of hookworms eggs in stool.
History and Symptoms
The majority of patients with ancylostomiasis are asymptomatic. Common symptoms of ancylostomiasis include: anorexia, flatulence, Diarrhea, Weight loss, Pallor, Dyspnea, Weakness, Generalized edema, Melena, Hematemesis, Dizziness, Syncope, Cough, Sneezing, Hemoptysis, Nausea, Vomiting, Pharyngeal irritation, Itchy, erythematous, serpiginous skin lesions.
Physical examination
Physical examination include: pallor, fatigue, dizziness, serpiginous, erythematous, and palpable plaque associated with edema, abdominal distension.
Lab Findings
Lab findings include: decreased hemoglobin, eosinophilia, presence of several live and motile worms in upper gastrointestinal endoscopy.
X Ray
There are no x-ray findings associated with ancylostomiasis.
CT
There are no CT findings associated with ancylostomiasis.
Other Diagnostic Studies
Other diagnostic studies for ancylostomiasis include upper gastrointestinal endoscopy, which demonstrates live and motile worms in GI tract.
Treatment
Medical Therapy
Anti-helminthic therapies are recommended among patients with ancylostomiasis. Efficacy of treatment varies according to the severity of infection, geographical distribution, and age groups. Multiple blood transfusion, iron supplements are also be given in severe cases.
Surgery
Surgical intervention is not recommended for the management of ancylostomiasis.
Primary Prevention
Effective measures for the primary prevention of ancylostomiasis include periodic mass anthelminthic treatment of at-risk populations, avoid gardening barefooted, patient education on proper hygiene and sanitation.