ISSN 2398-2942      

Ancylostoma braziliense

icanis

Synonym(s): A. braziliense, Hookworm


Introduction

Classification

Taxonomy

  • Superfamily: Ancylostomatoidea
  • Family: Ancylostomatidae
  • Genus: Ancylostoma
  • Species: braziliense

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Clinical Effects

Epidemiology

Habitat

  • Adults in small intestine.
  • Egg in environment. Eggs develop to L3 in warm and moist environment.
  • L3 infect animal by direct penetration of skin or through larval ingestion by the host.
  • Adult worms mature and shed eggs in small intestine.

Lifecycle

  • A. braziliense eggs are passed in the feces. First stage larva (L1) develops, the egg hatches and eventually infective L3 develop in humid and warm soil. Infection takes place by percutaneous penetration of the skin and passage of the larvae through the blood circulation, penetration of the lung alveoli, coughing the larvae into the trachea, and swallowing of the worms into the small intestine where they attach to the intestinal wall and develop as adults. Oral transmission by direct swallowing of L3 or ingestion of an infected paratenic host is also possible. Ingested larvae enter the stomach or intestinal wall where they molt to L4 and then return to the lumen where they mature. Transmammary transmission from the dam to pups has been described only for A. caninum (dog) and not for A. braziliense (dog and cat) or A. tubaeforme (cat). The prepatent period varies between 2-4 weeks and is longer for percutaneous transmission than for the oral route of infection.

Transmission

  • Infection can occur via L3 in the environment, or via infected paratenic hosts. Skin penetration is also known to occur, and neonatal pups may be infected via milk. Transplacental transmission has not been demonstrated with this species of AncylostomaA. braziliense has been shown to effect skin penetration more rapidly than A. caninum or A. celyanicum.
  • Percutaneous penetration of L3; oral infection with L3 or ingestion of paratenic host.

Pathological effects

  • Older animals develop a protective immunity to hookworms and are less likely to develop clinical signs of infection.
  • A. braziliense, like other hookworms, can cause anemia because of its blood-feeding activities. However ,A. braziliense is considered to consume relatively less blood than some other hookworms (5 ml per day per worm compared with 43 ml per worm per day for Ancylostoma caninum Ancylostoma caninum ).

Other Host Effects

  • A. braziliense occurs in dogs, cats and foxes. In comparison to A. caninum, it is not considered a good blood-sucker and is therefore of less pathogenic importance and does not induce severe anemia. A braziliense infection may cause loss of protein through intestinal leak of serum proteins manifested by hypoproteinemia in affected animals. Mild gastrointestinal signs including diarrhea may be seen in infected animals.

Host interaction

  • While primarily a parasite of dogs and wild canids, A. braziliense can also infect felids, and is a relatively common cause of cutaneous larva migrans in man. Strain differences may exist between worms with tropisms for dogs and cats. Clinical signs, including anemia, stunted growth and weight loss are most commonly seen in puppies. Light or moderate infections in adult dogs are relatively well-tolerated.
  • The potential of A. braziliense to penetrate skin is attributed to the production and secretion of hyaluuronidase and other enzymes. Blood feeding is facilitated by the secretion of anticoagulants.
  • Mild diarrhea caused by feeding of L4 and adults on the intestinal mucosa and loss of protein.
  • Dermatitis due to larval invasion of the skin, in particular the feet may occur.
  • A braziliense, in common with some other hookworms of domestic animals, can cause cutaneous larva migrans Visceral larva migrans (creeping eruption) in man. This species is thought to be one of the main causes of this zoonosis in many tropical /sub-tropical areas. There are also occasional reports of intestinal infection of man with A. braziliense. However, generally, man is considered as a dead end host. The lesions observed following skin penetration, in man and dogs, are similar, with inflammation, vesicle formation, eosinophil accumulation, and crusting.
  • A. braziliense has a mainly tropical, sub-tropical distribution. A number of small surveys give an indication of its overall prevalence. For example, it was found in 19% of stray dogs in Blomfontein, South Africa, 20% of stray dogs in Gauteng, South Africa, 49% in Tacuarembo, Uruguay.
  • The main importance of A. braziliense is its zoonotic potential. It is regarded as a major cause of cutaneous larva migrans (CLM) in humans. The infective larvae penetrate the skin and migrate through the dermis causing tortuous erythematous inflammtory tracts with a severe itch that may persist for weeks. CLM is commonly associated with infection from larvae originating in sand or at the beach.

Control

Control via chemotherapies

Control via environment

  • Where dogs are housed together measures to avoid fecal contamination of food and water, and regular removal of feces, will help to break the cycle of infection. Infected surfaces and soil may be disinfected cautiously with sodium borate, which is also toxic to plants. Predation on possible paratenic hosts such as rodents should be stopped.
  • Regular anthelmintic preventative measures include deworming every 3 months.

Vaccination

  • None available.

Diagnosis

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Traub R J, Robertson I D, Irwin P et al (2004) Application of a species-specific PCR-RFLP to identify Ancylostoma eggs directly from canine faeces. Vet Parasitol 123 (3-4), 245-255 PubMed.
  • Brenner M A & Patel M B (2003) Cutaneous larva migrans: the creeping eruption. Cutis 72 (2), 111-115 PubMed.
  • Minnaar W N, Krecek R C, Fourie L J (2002) Helminths in dogs from a peri-urban resource-limited community in Free State Province, South Africa. Vet Parasitol 107 (4), 343-349 PubMed.
  • Minnaar W N, Krecek R C (2001) Helminths in dogs belonging to people in a resource-limited urban community in Gauteng, South Africa. Onderstepoort J Vet Res 68 (2), 111-117 PubMed.
  • Conti Díaz I A (1999) [Human ectoparasitoses: current status in Uruguay]. Bol Chil Parasitol 54 (3-4), 101-103 PubMed.
  • Biolcati G, Alabiso A (1997) Creeping eruption of larva migrans--a case report in a beach volley athlete. Int J Sports Med 18 (8), 612-613 PubMed.
  • Shoop W L, Michael B F, Soll M D et al (1996) Efficacy of an ivermectin and pyrantel pamoate combination against adult hookworm, Ancylostoma braziliense, in dogs. Aust Vet J 73 (3), 84-85 PubMed.
  • Jelinek T, Maiwald H, Nothdurft H D et al (1994) Cutaneous larva migrans in travelers: synopsis of histories, symptoms, and treatment of 98 patients. Clin Infect Dis 19 (6), 1062-1066 PubMed.
  • Edelglass J W, Douglass M C, Stiefler R et al (1982) Cutaneous larva migrans in northern climates. A souvenir of your dream vacation. J Am Acad Dermatol (3), 353-358 PubMed.
  • Rep B H (1980) Pathogenicity of hookworms. The significance of population regression for the pathogenicity of hookworms. Trop Geogr Med 32 (3), 251-255 PubMed.
  • Vetter J C, Leegwater-vd Linden M E (1977) Skin penetration of infective hookworm larvae. III. Comparative studies on the path of migration of the hookworms Ancylostoma braziliense, Ancylostoma ceylanicum, and Ancylostoma caninum. Z Parasitenkd 53 (2), 155-158 PubMed.
  • Beaver P C (1956) The record of Ancylostoma braziliense as an intestinal parasite of man in North America. Am J Trop Med Hyg (4), 737-738 PubMed.

Other sources of information

  • Ballweber L R (2001) Parasites of the Gastrointestinal Tract 1. In: The practical veterinarian - Veterinary Parasitology. Boston, Mass: Butterworth Heinemann. pp 137-145.
  • Bowman D D (1999) Helminths. In: Georgis' Parasitology for Veterinarians. 7th edn. Philadelphia, PA. W B Saunders. pp 178-184.
  • Urquhart G M, Armour J, Duncan J L, Dunn A M, Jenning F W (eds) (1996) Veterinary helminthology. In: Veterinary Parasitology. Oxford, UK. Blackwell Science. pp 53-56.
  • Soulsby E J L (1982) Helminths, Arthropods and Protozoa of Domesticated Animals. 7th Edn.Ballière Tindall, London.

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