Ancylostoma braziliense

Ancylostoma braziliense is a species of hookworm belonging to the genus Ancylostoma. It is an intestinal parasite of domestic cats and dogs. Severe infection is often fatal to these pets, especially in puppies and kittens. The infection is particularly endemic in the southern United States. It is most often confused with the zoonotic hookworm species Ancylostoma ceylanicum because of their uncanny resemblance.[1]

Ancylostoma braziliense
Ancylostoma braziliense, mouth parts
Scientific classification
Kingdom: Animalia
Phylum: Nematoda
Class: Chromadorea
Order: Rhabditida
Family: Ancylostomatidae
Genus: Ancylostoma
Species:
A. braziliense
Binomial name
Ancylostoma braziliense
Gomes de Faria 1910

A. braziliense larvae can cause accidental infection in humans called cutaneous larval migration or creeping eruption, which produces severe itching in the skin. It is the most common skin infection in tropical region, particularly along the beaches of the Caribbean.[2][3]

Discovery and history

When A. braziliense was described by Gomes de Faria in 1910, and A. ceylanicum by Arthur Looss in 1911, the two species were regarded as synonymous because of their apparent similarities in almost all respect. Especially in 1913, comparison of specimens from human, dog, cat and lion infections in India led to the conclusion that they were definitely of the same species. In 1915 Gomes de Faria realised that the two were distinct species based on their anatomical structures. Till 1921 the two hookworms were accepted as a two valid species. However, in 1922 Gordon made an exhaustive comparison from specimens collected in Brazil, South Africa and India, and his conclusion was that there were no significant distinction. Other parasitologists were also convinced of this so that the two names were again considered synonymous. In 1951 Biocca made an elaborate study on different hookworms in the collection of London School of Hygiene and Tropical Medicine, the Liverpool School of Tropical Medicine and personal collections. He finally identified the defining characters between the two for classifying them as distinct species, which eventually gained general acceptance.[4]

Distribution

A. braziliense is endemic in the southern United States. It is also found in a number of subtropical regions around the world, including Central and South America, South Africa,[5] and southern Asia. In southern Asia, infection is confined to Indonesia, Borneo, and Malaysia.[1]

Physical description

Like many other worms, the female worm is larger than the male. Also, the females are more difficult to distinguish because the teeth sizes appear very similar among the various species of Ancylostoma. Male worms, however, have two broad lateral lobes and a smaller dorsal lobe with rays on the copulatory bursa. These bursal rays' aids in distinguishing the different species of Ancylostoma.[6]

Life cycle

Ancylostoma braziliense eggs are passed into the environment through the faeces of cats and dogs. The eggs incubate on warm, moist soil, where they hatch into larvae. The infective juvenile penetrate the skin of the host. At this stage, the larvae are present in the epidermis, hair follicles, and glands of the skin, sometimes extending to sebaceous glands where they form coils. Then they migrate to the heart and lung by moving along the blood circulation. In the lungs, the juveniles enter the alveoli and are propelled by cilia up the respiratory tract. From this, the host swallow them and deposit them in the small intestine. They get attached to the intestinal mucosa via the buccal capsule. Here they undergo two successive molts to become sexually mature individuals.[1]

Etymology

Having an etymology will definitely help in remembering the parasite.

Etymology: Ancylo = curved + stoma = mouth; braziliense for the geographical location where the worms were first found.[7]

Pathology
Main article: Cutaneous larva migrans

It can cause "creeping eruption" or "ground itch".[8][9] It occurs when the larvae from the faeces of cats and dogs accidentally penetrate the human skin, causing severe itching and skin eruption. It is the most common ailment of tropically acquired dermatitis, particularly along the beaches of the Caribbean. However, humans are not the natural definitive hosts, and are therefore a dead-end for the parasites. In humans, the larvae die after few months without further development.[10]

Symptoms

Ancylostoma braziliense is a parasite that infects cats and dogs and occasionally humans. And, they survive by eating blood from the intestine of cats and dogs, causing anemia. Pale gums and weakness are common signs of anemia. The infected animals also experience significant weight loss, bloody diarrhea, and are not able to grow up to their right size. Other symptoms like, skin irritation and itching is also caused by the larvae burrowing into the skin.[11]

Diagnosis and treatment

A. braziliense is difficult to differentiate from other hookworms. Microscopic examination of scatological samples can identify the eggs as they are generally smaller than those of other species.[12]

Most benzimidazoles are effective. Mebendazole, triclabendazole and fenbendazole are commonly used. Ivermectin and pyrantel pamoate are also effective. The combination of ivermectin 6 μg/kg and pyrantel pamoate at 5.0 mg/kg is 100% efficacious against adult worms in dogs.[13] Human infection in case of cutaneous larva migrans is treated with oral thiabendazole at 500 mg in 4 daily dose.[14]

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References
  1. Chapman S (2012). "Ancylostoma braziliense". Animal Diversity Web. Regents of the University of Michigan. Retrieved 2013-06-30.
  2. Bowman, Dwight D.; Montgomery, Susan P.; Zajac, Anne M.; Eberhard, Mark L.; Kazacos, Kevin R. (2010). "Hookworms of dogs and cats as agents of cutaneous larva migrans". Trends in Parasitology. 26 (4): 162–167. doi:10.1016/j.pt.2010.01.005. PMID 20189454.
  3. Feldmeier, H.; Schuster, A. (2012). "Mini review: hookworm-related cutaneous larva migrans". European Journal of Clinical Microbiology & Infectious Diseases. 31 (6): 915–918. doi:10.1007/s10096-011-1404-x. PMID 21922198. S2CID 14834364.
  4. Yushida Y (1971). "Comparative studies on Ancylostoma braziliense and Ancylostoma ceylanicum. I. The adult stage". The Journal of Parasitology. 57 (5): 983–989. doi:10.2307/3277850. JSTOR 3277850. PMID 5156464.
  5. 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". Veterinary Parasitology. 107 (4): 343–349. doi:10.1016/S0304-4017(02)00155-3. PMID 12163245.
  6. "ADW: : INFORMATION". Animal Diversity Web. Retrieved 2018-04-26.
  7. "Ancylostoma braziliense | American Association of Veterinary Parasitologists". www.aavp.org. Retrieved 2018-04-26.
  8. Shinkar RM, Stocks R, Thomas E (2005). "Cutaneous larva migrans, creeping eruption, sand worm". Arch. Dis. Child. 90 (10): 998. doi:10.1136/adc.2005.073197. PMC 1720113. PMID 16177155.
  9. Tierney, Lawrence M.; McPhee, Stephen J.; Papadakis, Maxine A. (2008). Current medical diagnosis & treatment, 2008. McGraw-Hill Medical. p. 1323. ISBN 978-0-07-149430-4.
  10. Brenner MA, Patel MB (2003). "Cutaneous larva migrans: the creeping eruption". Cutis. 72 (2): 111–115. PMID 12953933.
  11. "CDC – DPDx – Hookworm". www.cdc.gov. 2017-12-13. Retrieved 2018-04-26.
  12. Lucio-Forster A, Liotta JL, Yaros JP, Briggs KR, Mohammed HO, Bowman DD (2012). "Morphological differentiation of eggs of Ancylostoma caninum, Ancylostoma tubaeforme, and Ancylostoma braziliense from dogs and cats in the United States". J Parasitol. 98 (5): 1041–1044. doi:10.1645/GE-2928.1. PMID 22394087. S2CID 264410.
  13. Shoop WL, Michael BF, Soll MD, Clark JN (1996). "Efficacy of an ivermectin and pyrantel pamoate combination against adult hookworm, Ancylostoma braziliense, in dogs". Aust Vet J. 73 (3): 84–85. doi:10.1111/j.1751-0813.1996.tb09981.x. PMID 8660218.
  14. O'Quinn JC, Dushin R (2005). "Cutaneous larva migrans: case report with current recommendations for treatment". J Am Podiatr Med Assoc. 95 (3): 291–294. doi:10.7547/0950291. PMID 15901819.
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