Ancylostoma


Article Author:
Mochamad Helmi Aziz


Article Editor:
Kamleshun Ramphul


Editors In Chief:
Donald Kushner
Annabelle Dookie


Managing Editors:
Orawan Chaigasame
Carrie Smith
Abdul Waheed
Frank Smeeks
Kristina Soman-Faulkner
Benjamin Eovaldi
Radia Jamil
Sobhan Daneshfar
Saad Nazir
William Gossman
Pritesh Sheth
Hassam Zulfiqar
Navid Mahabadi
Steve Bhimji
John Shell
Matthew Varacallo
Ahmad Malik
Mark Pellegrini
James Hughes
Beata Beatty
Hajira Basit
Phillip Hynes


Updated:
2/10/2019 8:16:25 AM

Introduction

Ancylostoma duodenale, the human hookworm, is the most common parasitic infection in countries with poor access to adequate water, sanitation, and hygiene. A. duodenale along with other soil-transmitted helminths (STH) are transmitted through contact with contaminated soil. In the last few decades, zoonotic transmission of 3 other Ancylostoma species has been documented. In these cases, the transmission occurred from domesticated animals to humans.[1][2][3][4]

Etiology

A. duodenale as well as, Ancylostoma braziliense, Ancylostoma caninum, and Ancylostoma ceylanicum, are anthropophilic human hookworms transmitted from infected soil and transmitted via contact with domesticated animals, such as dogs and cats which are the definitive host of these species. A. duodenale and A. ceylanicum cause intestinal infections with gastrointestinal (GI) symptoms, anemia, and physical and cognitive impairment. Moreover, A. duodenale pulmonary symptoms can occur in infected humans. Furthermore, all Ancylostoma species can cause the creeping skin eruption called cutaneous larva migrans (CLM). Although it is rare, eosinophilic enteritis may occur due to A. caninum infection.[5][6][7]

Epidemiology

It is estimated that more than 1.5 billion people worldwide are at risk for infection with Ancylostoma and the other STH. Half of the infections occur in the Asia and the Pacific where the tropical climate, overcrowded population, poor hygiene, and poor sanitation are present. Ancylostoma, along with the other hookworms, cause more disability than mortality. Hookworm-associated malnutrition and anemia account for the loss up to 4.1 million disability-adjusted-life-years (DALY) annually. The highest at-risk population to contract the Ancylostoma infections are the pre-school and school-aged children and travelers who returned from tropical countries. Additionally, people in close contact with dogs and cats are at-risk to acquire zoonotic Ancylostoma infection. The incidence of Ancylostoma infection is tied to seasonal distribution where during the summer-autumn period, the incidence is more prevalent. Mixed infections with more than one Ancylostoma species are common in humans.

Pathophysiology

After the eggs of Ancylostoma pass from the stool of their host, the eggs hatch into larvae. In favorable conditions, this occurs in 1 to 2 days. The hatched rhabditiform (non-infective) larvae grow in the feces or soil for 5 to 10 days and mature into filariform (infective) larvae. The filariform larvae can penetrate the human skin via hair follicles, enter the lymphatic system, and migrate to the heart and lungs. In the lungs, the larvae penetrate the pulmonary alveoli, where they ascend from the bronchial tree to the pharynx, can be coughed up, swallowed, and reach the small intestine where they mature into male or female blood-feeding-adults. The mating adult worms can produce thousands of eggs, and the cycle starts over. Furthermore, the filariform larvae can spread via oral ingestion and trans mammary route where the larvae directly mature in the small intestine or stay dormant in human skeletal musculature. The dormant larvae have been proven responsible for vertical transmission during breastfeeding and are possibly the cause of transplacental infection.

History and Physical

The majority of people who are infected with Ancylostoma are from the endemic areas, or they are travelers who visit the endemic areas. Healthcare practitioners should take a careful history, including asking whether patients walk barefoot in endemic areas, have contact with domesticated animals, and inquire about nutritional status and growth of pediatric patients to determine the presence of Ancylostoma infection.

Some people can develop an Ancylostoma infection without any symptoms, while the others may have mild to severe symptoms. There are 3 phases: invasion, migration, and establishment in the intestine. During the invasion stage, the filariform larvae penetrate the skin causing local irritation, intense itchiness, and vesicular rash lesions that are called ground itch. In some cases, zoonotic Ancylostoma, for which humans are incompatible hosts, the larvae only penetrate and live at the skin causing the condition known as CLM or creeping eruption. During the CLM, erythema and itchy papules are present. These are followed by linear, serpiginous, and elevated ridges due to larvae tunneling phenomenon. The CLM lesions usually occur on the upper and lower extremities, although they have been reported on some unusual sites such as abdomen and penis. However, in rare cases, A. caninum can induce eosinophilic enteritis marked by abdominal pain and peripheral blood eosinophilia.

In the migration phase, larvae escape to the lungs and GI tract and produce organ-related symptoms such as a cough, sore throat, and GI discomfort. Loeffler syndrome, the pulmonary hypersensitive response due to A. duodenale larval migration through lung tissue can occur; although, it is rare. Serum immunoglobulin E (IgE) and peripheral blood eosinophilia are elevated during Loeffler syndrome. If A. duodenale infect a person through the oral route (known as Wakana syndrome), they may experience nausea, vomiting, pharyngeal irritation, cough, dyspnea, and hoarseness.

The most serious symptoms of Ancylostoma infection develop during the last phase when the adult worms establish themselves in the human intestine. Using their buccal capsule and teeth, the adult worms attach to the mucosa and rupture capillaries and arterioles to feed, and this results in blood and protein loss. Chronic infection in the intestine results in iron-deficiency anemia, accompanied by the loss of appetite, abdominal discomfort, and malnutrition due to protein deficiency. This can cause physical and cognitive impairment.

Evaluation

Clinical symptoms of Ancylostoma infection can be misleading because the symptoms are also present with other infections and nutritional-deficiency status. Routine blood findings can reveal iron-deficient anemia, peripheral blood eosinophilia, and sometimes, elevated IgE levels. Chest radiography may reveal diffuse alveolar infiltrates during the migration phase, but this is not helpful when the worms have already invaded the gut. These tests should be interpreted carefully since other helminths infections such as strongyloidiasis and ascariasis show the same blood and radiologic profile.

Conventional stool examinations, such as the Kato-Katz and formalin-ether concentration technique, are the gold-standard of diagnosing Ancylostoma infection by detecting the presence of the eggs and adult worms. The morbidity of Ancylostoma infection can be determined by measuring the number of eggs per gram (EPG) in the stool. However, in some cases when the number of eggs is very low or after mass drug administration (MDA), stool examination is not helpful. Therefore, several laboratories have developing molecular-based examinations targeting the internal transcribed spacer (ITS) and 5.8S of the worms in the last few years. These molecular assays are still being validated to replace the conventional methods.

In case of CLM, stool examination is not very helpful, and diagnosis can be made clinically based on skin presentation since the larvae will be confined to the skin. If eosinophilic enteritis is suspected, the eggs will not be found in the stool because humans are not definitive hosts of A. caninum. Colonoscopy and laparotomies to obtain eosinophilic tissues for histopathology features to assess eosinophilic enteritis can be performed, but they are not recommended for routine testing. Serologic tests for A. caninum are not widely available, but several research laboratories have developed serologic testing for this species.

Treatment / Management

A single dose of albendazole or mebendazole or 3-day dose of albendazole, mebendazole, or pyrantel pamoate is the recommended treatment for Ancylostoma infection. Ivermectin and pyrantel pamoate are the recommended treatment for A. ceylanicum infection, although benzimidazoles drugs are effective as well. For pregnant women, deworming treatments are recommended during the second or third trimester of pregnancy after considering the risks and benefits of treatment. Iron replacement and nutritional support should be included inAncylostoma management of infection to reduce the morbidity rates. After 2 to 3 weeks of treatment, stool examination and blood workup should be performed to evaluate treatment efficacy and to exclude the presence of any reinfection.[8][9][10]

Although CLM is a self-limited disease, complications such as secondary bacterial infection may occur if the CLM is untreated. A single dose of ivermectin or 3-day course of albendazole could be used to stop the movement of the larvae. Topical application of 10% to 15% thiabendazole is also proven effective for CLM. Domesticated animals should be treated as well with anthelminthic drugs such as pyrantel pamoate, dichlorvos, febantel, fenbendazole, and mebendazole to stop the transmission cycle of the zoonotic Ancylostoma species.

Differential Diagnosis

All diseases that can cause chronic blood loss and iron-deficient anemia, for example, intestinal malignancy, intestinal polyps, hemolytic anemia, and other STH infection, should be ruled out to establish infection by Ancylostoma diagnosis. Contact dermatitis, migratory myiasis, scabies infection, and cercarial dermatitis have a common clinical presentation with CLM. Thus, they are hard to distinguish.

Deterrence and Patient Education

MDA of benzimidazole drugs such as albendazole and mebendazole are used as control strategies using preventive chemotherapy in endemic areas. However, other than preventive chemotherapy, improving the general sanitation and hygiene can have a great impact on preventing infection and reinfection by Ancylostoma. Other easy preventive measurements include avoiding walking barefoot on beaches or endemic areas, cleaning up and preventing animal waste in public areas, and improving sanitary disposal of human waste.

Pearls and Other Issues

After many years of using anthelmintic MDA to treat and control Ancylostoma and other STH infections, the transmission of those worms still ongoing. Hence, drug-resistance exists. The increasing rates of drug failure and inability to provide long-term protection raise concern for new ways to manage Ancylostoma and other STH infections, especially in endemic areas. Vaccines that could provide long-term protection and the ability to stop disease transmission have been developed and target several antigens of Ancylostoma species. The availability of the vaccine will be a huge benefit for public health to combat these infections.

Enhancing Healthcare Team Outcomes

The management of ancylostoma infection is with a multidisciplinary team consisting of an infectious disease expert, emergency department physician, pharmacist and an internist. The diagnosis can be difficult because the infection is not common in the US. The emergency department physician and nurse practitioner should be aware that the majority of people who are infected with Ancylostoma are from the endemic areas, or they are travelers who visit the endemic areas. Healthcare practitioners should take a careful history, including asking whether patients walk barefoot in endemic areas, have contact with domesticated animals, and inquire about nutritional status and growth of pediatric patients to determine the presence of Ancylostoma infection. Once the diagnosis is made, the treatment with drugs like albendazole and mebendazole is effective.

Healthcare workers should emphasize to the traveler the importance of improving the general sanitation and hygiene. Other easy preventive measurements include avoiding walking barefoot on beaches or endemic areas, cleaning up and preventing animal waste in public areas, and improving sanitary disposal of human waste.


Interested in Participating?

We are looking for contributors to author, edit, and peer review our vast library of review articles and multiple choice questions. In as little as 2-3 hours you can make a significant contribution to your specialty. In return for a small amount of your time, you will receive free access to all content and you will be published as an author or editor in eBooks, apps, online CME/CE activities, and an online Learning Management System for students, teachers, and program directors that allows access to review materials in over 500 specialties.

Improve Content - Become an Author or Editor

This is an academic project designed to provide inexpensive peer-reviewed Apps, eBooks, and very soon an online CME/CE system to help students identify weaknesses and improve knowledge. We would like you to consider being an author or editor. Please click here to learn more. Thank you for you for your interest, the StatPearls Publishing Editorial Team.

Ancylostoma - Questions

Take a quiz of the questions on this article.

Take Quiz
An 8-year-old boy presents with his mother with severe itching. His mother said that the intense itching on the right sole of his skin started two-weeks ago after they went on holiday to the beach. His mother also notices that on the itchy area there was redness and a serpiginous rash that advanced in several days. What is most likely the diagnosis?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
A 52-year-old male complained of watery diarrhea with general weakness for the past 12 days. He had no history of chronic metabolic-cardiovascular disorder or malignancy. Before he had diarrhea, he had been healthy. He denied that he had itch or rash symptoms during the past 2 months, but he mentioned that he had transient nausea, vomiting, dyspnea, cough, and pharyngeal irritation in the past 2 months. He had a recent history of travel where he drunk spring water in the tropical area, but he denied that he had an animal contact in the past 2 months. During laboratory evaluation, hypochromic anemia, mild leukocytosis, and eosinophilia were present. Stool culture was negative for any bacterial pathogen, and Kato-Katz stool examination was negative for ova or parasites. What is most likely the pathogen infecting this patient?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
Which Ancylostoma species that could infect and maintain its life cycle in humans and other mammalian hosts such as cats, dogs, and hamsters?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
A 33-year-old farmer was referred to the tertiary hospital due to fever, shortness of breath, and chest pain for two weeks. He had no history of chronic disease, and before the present illness, he had been perfectly healthy. He also did not have any history of medication or travel for the past 3 months. During the first hospitalization, he was diagnosed having pneumonia of the left upper lobe and treated with antibiotics. Ten days after the treatment, the pneumonia progressed. The differential white blood count revealed 46% of eosinophils, and the serum IgE was elevated. The sputum culture was negative for any bacteria, the direct smear of the sputum was negative for fungi or acid bacilli, and blood culture was negative for any culturable bacteria. Stool examination was negative for ova or any parasites. Surprisingly, during hospitalization, the chest X-ray revealed migratory infiltrates of the lungs. What could be the possible condition in this patient?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
A 35-year-old woman was transferred to the tertiary hospital, with shortness of breath and dizziness which has lasted for years. She lived as a housewife in a remote rural area and had no history of traveling in the past few years. She mentioned that she had no contact with animals, but she cultivated a small dooryard farm at home. Last year, she had been treated for anemia and received blood transfusions in the hospital. On physical examination at admission, she was pale, ill-looking, and undernourished, with stable vital signs. Laboratory results revealed overt severe iron-deficiency anemia and mild eosinophilia on differential blood count. Liver and renal functions were within normal limits. Stool examination was negative for occult blood and ova of parasites. Gastroduodenoscopy found hyperemic mucosa and numerous 8 mm long moving worms in the duodenum. What kind of treatment should be given to the patient?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up

Ancylostoma - References

References

Furtado LFV,de Aguiar PHN,Zuccherato LW,Teixeira TTG,Alves WP,da Silva VJ,Gasser RB,Rabelo ÉML, Albendazole resistance induced in Ancylostoma ceylanicum is not due to single-nucleotide polymorphisms (SNPs) at codons 167, 198, or 200 of the beta-tubulin gene, indicating another resistance mechanism. Parasitology research. 2019 Jan 29;     [PubMed]
DE-LA-Rosa-Arana JL,Tapia-Romero R, Frequency of Helminth Eggs in Faeces of Puppies Living in Urban or Rural Environments of Mexico City. Iranian journal of parasitology. 2018 Oct-Dec;     [PubMed]
Bryant AS,Hallem EA, Terror in the dirt: Sensory determinants of host seeking in soil-transmitted mammalian-parasitic nematodes. International journal for parasitology. Drugs and drug resistance. 2018 Dec;     [PubMed]
Shu-Ying X,Zhi-Hong G,Zhe C,Chun-Qin H,Wei-Ming L,Wei-Sheng J,Xiao-Jun Z, [Current status of human hookworm infection in Jiangxi Province in 2014]. Zhongguo xue xi chong bing fang zhi za zhi = Chinese journal of schistosomiasis control. 2018 Jun 4;     [PubMed]
Gordon CA,Kurscheid J,Jones MK,Gray DJ,McManus DP, Soil-Transmitted Helminths in Tropical Australia and Asia. Tropical medicine and infectious disease. 2017 Oct 23;     [PubMed]
Bojar H,Kłapeć T, Contamination of selected recreational areas in Lublin Province, Eastern Poland, by eggs of Toxocara spp., Ancylostoma spp. and Trichuris spp. Annals of agricultural and environmental medicine : AAEM. 2018 Sep 25;     [PubMed]
O'Connell EM,Mitchell T,Papaiakovou M,Pilotte N,Lee D,Weinberg M,Sakulrak P,Tongsukh D,Oduro-Boateng G,Harrison S,Williams SA,Stauffer WM,Nutman TB, Ancylostoma ceylanicum Hookworm in Myanmar Refugees, Thailand, 2012-2015. Emerging infectious diseases. 2018 Aug;     [PubMed]
Farrell SH,Coffeng LE,Truscott JE,Werkman M,Toor J,de Vlas SJ,Anderson RM, Investigating the Effectiveness of Current and Modified World Health Organization Guidelines for the Control of Soil-Transmitted Helminth Infections. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America. 2018 Jun 1;     [PubMed]
O'Connell EM,Nutman TB, Molecular Diagnostics for Soil-Transmitted Helminths. The American journal of tropical medicine and hygiene. 2016 Sep 7;     [PubMed]
Vercruysse J,Albonico M,Behnke JM,Kotze AC,Prichard RK,McCarthy JS,Montresor A,Levecke B, Is anthelmintic resistance a concern for the control of human soil-transmitted helminths? International journal for parasitology. Drugs and drug resistance. 2011 Dec;     [PubMed]

Disclaimer

The intent of StatPearls is to provide practice questions and explanations to assist you in identifying and resolving knowledge deficits. These questions and explanations are not intended to be a source of the knowledge base of all of medicine, nor is it intended to be a board or certification review of Surgery-Podiatry APMLE Part 3. The authors or editors do not warrant the information is complete or accurate. The reader is encouraged to verify each answer and explanation in several references. All drug indications and dosages should be verified before administration.

StatPearls offers the most comprehensive database of free multiple-choice questions with explanations and short review chapters ever developed. This system helps physicians, medical students, dentists, nurses, pharmacists, and allied health professionals identify education deficits and learn new concepts. StatPearls is not a board or certification review system for Surgery-Podiatry APMLE Part 3, it is a learning system that you can use to help improve your knowledge base of medicine for life-long learning. StatPearls will help you identify your weaknesses so that when you are ready to study for a board or certification exam in Surgery-Podiatry APMLE Part 3, you will already be prepared.

Our content is updated continuously through a multi-step peer review process that will help you be prepared and review for a thorough knowledge of Surgery-Podiatry APMLE Part 3. When it is time for the Surgery-Podiatry APMLE Part 3 board and certification exam, you will already be ready. Besides online study quizzes, we also publish our peer-reviewed content in eBooks and mobile Apps. We also offer inexpensive CME/CE, so our content can be used to attain education credits while you study Surgery-Podiatry APMLE Part 3.