Animal Diversity Web

Ge­o­graphic Range

An­cy­lostoma braziliense is the cat and dog hook­worm. En­demic in the south­ern United States, this species is pre­sent in a num­ber of sub­trop­i­cal re­gions around the world, in­clud­ing Cen­tral and South Amer­ica, and South­ern Asia. In South­ern Asia, the dis­tri­b­u­tion of An­cy­lostoma is con­fined to In­done­sia, Bor­neo, and Malaysia. The rea­son for this ge­o­graph­i­cal re­stric­tion is con­trary to an ex­pected wide­spread dis­tri­b­u­tion of the hook­worm due to the in­ter­min­gling of human pop­u­la­tions. Hu­mans and do­mes­tic an­i­mals have in­tro­duced species of An­cy­lostoma in other places around the world, such as Aus­tralia. (Richey, et al., 1996; Traub, et al., 2007)

• Biogeographic Regions
• nearctic
  • native
• oriental
  • introduced
• neotropical
  • native
• australian
  • introduced

Habi­tat

An­cy­lostoma braziliense eggs are passed into the en­vi­ron­ment through feces of cats and dogs. The eggs in­cu­bate on warm, moist soil. Adult hook­worms live in the small in­testines of many ver­te­brates. (Bal­four, et al., 2002; Richey, et al., 1996; Roberts and Janovy Jr, 2009)

• Habitat Regions
• tropical
• terrestrial

• Other Habitat Features
• urban
• suburban
• agricultural

Phys­i­cal De­scrip­tion

Hook­worms in the phy­lum Ne­ma­toda share a com­mon mor­phol­ogy as the an­te­rior end curves like a hook and the buc­cal cap­sule is scle­ro­tized and lined with teeth. Within the fam­ily An­cy­losto­mi­dae, the an­te­rior end is curved dor­sally. The ne­ma­tode body is cov­ered with a non-liv­ing cu­ti­cle shed by molt­ing. The width of the cu­tic­u­lar stri­a­tion pat­terns of A. braziliense is 3.45 µm.

Ne­ma­tode guts con­sist of a tube with an esoph­a­gus com­posed of the cor­pus, isth­mus, and bulb. Within the An­cy­losto­mi­dae, the esophogus is stout and mus­cu­lar. The buc­cal cav­ity (be­tween the mouth and esoph­a­gus) has a thick cu­tic­u­lar lin­ing which is large and heav­ily scle­ro­tized, termed a buc­cal cap­sule. Males of A. braziliense have a tu­ber­cu­lar process that is found at the buc­cal cap­sule of the mouth.

Male A. braziliense have two broad lat­eral lobes and a smaller dor­sal lobe with rays on the cop­u­la­tory bursa. The bur­sal rays dis­tin­guish dif­fer­ent species of An­cy­lostoma. In A. braziliense, the lat­eral bur­sal rays are sep­a­rated at the tips, and the po­si­tion of at­tach­ment of the ex­tern­odor­sal ray is unique in that it is closer to the be­gin­ning of the dor­sal trunk than in other species.

Fe­males are more dif­fi­cult to dis­tin­guish be­tween dif­fer­ent species, and usu­ally the teeth are the only di­ag­nos­tic tool that can be used. There is a prob­lem with this method, how­ever, be­cause for many species, the size and shape of the teeth do not ap­pear to be sig­nif­i­cantly unique. (Roberts and Janovy Jr, 2009; Traub, et al., 2007; Yoshida, 1971)

• Other Physical Features
• ectothermic
• heterothermic
• bilateral symmetry

• Sexual Dimorphism
• female larger

• Range length

  7.67 to 8.33 mm

  0.30 to 0.33 in

De­vel­op­ment

After the eggs are passed into the en­vi­ron­ment through the feces of cats or dogs, they hatch into first-stage ju­ve­niles. The first-stage ju­ve­nile feeds on soil bac­te­ria and feces for about a day. In the early stages of de­vel­op­ment, A. braziliense is non­in­fec­tious, and has a rhab­di­ti­form esoph­a­gus. The rhab­di­ti­form esoph­a­gus is char­ac­ter­is­tic of a feed­ing stage. Over a pe­riod of sev­eral days, the ne­ma­tode molts and reaches the third stage of de­vel­op­ment where be­comes an in­fec­tious fi­lar­i­form ju­ve­nile. The fi­lar­i­form esoph­a­gus is char­ac­ter­is­tic of non-feed­ing or liq­uid feed­ing stages, and the cor­pus is re­duced. At the third stage, the ju­ve­nile stops feed­ing be­cause it has ac­cu­mu­lated all the nu­tri­ents needed, and de­vel­op­ment pauses as the ju­ve­nile waits for a host. Once a proper de­fin­i­tive host has been found, the ju­ve­nile pen­e­trates the skin. At this stage, A. braziliense is found in the epi­der­mis, fol­li­cles, and glands of the skin, some­times ex­tend­ing to se­ba­ceous glands where they form coils. The ju­ve­nile mi­grates from the skin, and is car­ried to the heart and lungs by the blood­stream. In the lungs, the ju­ve­nile breaks into the alve­oli and is pro­pelled by cilia up the res­pi­ra­tory tract, where it is swal­lowed and ends up in the small in­tes­tine. The ju­ve­nile at­tachs to the in­testi­nal mu­cosa via the buc­cal cap­sule, and ma­tures to adult form by molt­ing twice. Once the last molt has fin­ished, the adult hook­worm is sex­u­ally ma­ture and ready to mate.

Al­though hu­mans can be­come in­fected, they are not true de­fin­i­tive hosts of A. braziliense. As a re­sult, the ju­ve­niles only mi­grate along the epi­der­mis, cre­at­ing le­sions. The ju­ve­nile even­tu­ally dies, never mak­ing it to the cir­cu­la­tory sys­tem or reach­ing adult­hood in the in­tes­tine. (Bal­four, et al., 2002; Brand and Haw­don, 2004; Bren­ner and Patel, 2003; Costa, et al., 2009; Nor­ris, 1971)

• Development - Life Cycle
• diapause

Re­pro­duc­tion

Males and fe­males mate using di­rect sperm trans­fer. Males have spicules that keep the fe­male re­pro­duc­tive open­ing gap­ing dur­ing sperm trans­fer. (Roberts and Janovy Jr, 2009)

• Mating System
• polygynandrous (promiscuous)

Males and fe­males of A. braziliense have very dif­fer­ent roles dur­ing in­fec­tion and re­pro­duc­tion. The pri­mary role of fe­males is to lay eggs, and once a fe­male has suc­cess­fully in­fected a de­fin­i­tive host, it takes a min­i­mum of five weeks be­fore eggs are pro­duced. Males likely exist pri­mar­ily to fer­til­ize eggs, and pro­duce pro­tease in­hibitors. The role of pro­tease in­hibitors is still largely un­known, but thought that they are im­por­tant for par­a­sitism and sur­vival within the host.

Few stud­ies have been con­ducted on the re­pro­duc­tive genes of ne­ma­todes, but re­cent work has iden­ti­fied gen­der spe­cific genes in A. braziliense. Sci­en­tists in­ves­ti­gated sex spe­cific genes of un­known func­tion in A. braziliense, and com­pared them to sex spe­cific genes of known func­tion in other species. By look­ing for ho­mol­ogy, sci­en­tists dis­cov­ered that males of dif­fer­ent species also se­crete pro­tease in­hibitors, and that they some­how func­tion to en­sure sur­vival within the host. Sim­i­lar­i­ties among dif­fer­ent species of ne­ma­todes with known gene func­tion will help to de­fine the func­tion of pre­vi­ously un­known genes in A. braziliense. Such re­search also promises to bet­ter show the dif­fer­ent roles of males and fe­males in in­fec­tion, re­pro­duc­tion, and sur­vival within the host. (Costa, et al., 2009)

• Key Reproductive Features
• sexual
• fertilization
  • internal
• oviparous

After eggs are laid, there is no parental in­vest­ment. (Costa, et al., 2009)

• Parental Investment
• no parental involvement
• pre-hatching/birth
  • provisioning

Lifes­pan/Longevity

The longest lifes­pan is un­known, and the ex­pected lifes­pan varies de­pend­ing on the health of the host and the num­ber of adults caus­ing the in­fec­tion. (Bal­four, et al., 2002)

Be­hav­ior

The be­hav­ior of A. braziliense has not been widely stud­ied. How­ever, be­hav­ioral pat­terns of A. can­inum can be used as a way to gain a un­der­stand­ing of how in­fec­tive lar­vae lo­cate their hosts.

Tem­per­a­ture, light, and hu­mid­ity af­fect the be­hav­ioral pat­terns of A. can­inum, whereas car­bon diox­ide lev­els, light, and pH have no ef­fect. A tem­per­a­ture of ap­prox­i­mately 40 deg C at­tracts a ju­ve­nile, and it creeps to­wards the warmth in a snake-like way. Tem­per­a­tures above or below 40 deg C will not as ef­fec­tively stim­u­late host pen­e­tra­tion.

In ad­di­tion to warm tem­per­a­ture, host sur­face ex­tracts and serum also stim­u­late pen­e­tra­tion. Specif­i­cally, pen­e­tra­tion is stim­u­lated when ju­ve­niles of A. can­inum come into con­tact with the sur­face ex­tract of dogs, a de­fin­i­tive host. Sur­face ex­tracts and serum of other in­ter­me­di­ate hosts such as hu­mans, are not as ef­fec­tive in stim­u­lat­ing pen­e­tra­tion.

Lastly, A. can­inum and A. braziliense can­not sur­vive in­ges­tion by a de­fin­i­tive host, and as a re­sult, the ju­ve­niles do not es­tab­lish them­selves on pro­jec­tions like the ju­ve­niles of other ne­ma­tode species. In­stead, A. can­inum and A. braziliense pen­e­trate the skin of their hosts. Ex­cep­tions have been found among some species of An­cy­lostoma, how­ever, where the ju­ve­niles have sur­vived oral in­ges­tion by their de­fin­i­tive host. (Granzer and Haas, 1991)

• Key Behaviors
• parasite
• motile

Com­mu­ni­ca­tion and Per­cep­tion

Sen­sory or­gans on ne­ma­todes in­clude papil­lae, which are tac­tile re­cep­tors, and am­phids, which are chemore­cep­tors. Chem­i­cal cues are likely used to at­tract a mate. Sex­ual pheromones have been iden­ti­fied for at least 40 species of ne­ma­todes. Once a male and fe­male en­counter each other, tac­tile cues are used for re­pro­duc­tion.

Males of A. braziliense and A. can­inum can mon­i­tor the host-par­a­site re­la­tion­ship, but it is not known ex­actly how. An­cy­lostoma can­inum acts in­de­pen­dently and won't fol­low ju­ve­niles that have al­ready lo­cated and pen­e­trated a host. Re­cent stud­ies have shown that males se­crete pro­tease in­hibitors, which are thought to play an im­por­tant role in in­fec­tion and sur­vival within the host.

Sur­vival modes of A. braziliense have only re­cently been stud­ied. Pre­vi­ous re­search on other hook­worm species, such as Neca­tor amer­i­canus, has pro­vided the frame­work of how hook­worms evade the host im­mune sys­tem. Nec­tor amer­i­canus par­a­sitizes hu­mans, and it se­cretes prod­ucts that bind to human cells, in­hibit­ing a proper im­mune re­sponse. By tam­per­ing with the human im­mune sys­tem, N. amer­i­canus can en­sure its sur­vival. (Granzer and Haas, 1991; Roberts and Janovy Jr, 2009; Teix­eira-Car­valho, et al., 2008)

• Communication Channels
• tactile
• chemical

• Perception Channels
• infrared/heat
• tactile
• chemical

Food Habits

Adults feed on blood and in­testi­nal flu­ids in the gut of their host, lead­ing to iron de­fi­ciency and ane­mia for the host. The way in which hook­worms di­gest their blood meal is still being stud­ied, but it is known that adult hook­worms use a cas­cade of pro­teins to lyse red blood cells. A. braziliense ju­ve­niles do not feed on blood, rather they feed on dung and soil bac­te­ria. (Don, et al., 2007)

• Primary Diet
• carnivore
  • eats body fluids

• Animal Foods
• blood
• body fluids

• Other Foods
• dung
• microbes

Pre­da­tion

There are no known preda­tors of A. braziliense. (Granzer and Haas, 1991)

Ecosys­tem Roles

An­cy­lostoma braziliense is an en­dopar­a­site of cats and dogs. Adult hook­worms eat blood from the in­tes­tine of cats and dogs, caus­ing ane­mia. (Don, et al., 2007)

• Ecosystem Impact
• parasite

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

A. braziliense has no pos­i­tive im­pact on hu­mans. (Bal­four, et al., 2002)

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

Hu­mans are ac­ci­den­tal, dead-end hosts for hook­worms. In­fec­tious ju­ve­niles can pen­e­trate the epi­der­mis of hu­mans by tak­ing ad­van­tage of bro­ken skin or hair fol­li­cles. In­side the human host, the ju­ve­niles mi­grate through the epi­der­mis, com­monly called the creep­ing erup­tion. As the ju­ve­niles mi­grate, they cause ser­pingi­nous erup­tions on the skin, and they cause a tin­gling sen­sa­tion. The le­sions on the skin are typ­i­cally 3 mm wide, but in some cases the le­sions can ex­pand to reach 15 to 20 cm. The ju­ve­niles ad­vance through the epi­der­mis at a rate of a few mm per day. As the worms mi­grate, they fre­quently change di­rec­tion, and vesi­cles begin to form in their trail. The vesi­cles often be­come in­flamed, and as a re­sult the trails of the ju­ve­nile are vis­i­ble on the sur­face of the skin. The most com­mon site of in­fec­tion of hu­mans is the feet. Ad­di­tion­ally, it is quite com­mon for chil­dren to be­come in­fected on their but­tocks be­cause thin swim wear does not pro­vide a suf­fi­cient bar­rier to the in­fec­tious ju­ve­niles found in the warm, moist sand of trop­i­cal beaches.

Al­though the ju­ve­niles cre­ate un­com­fort­able le­sions on the skin, they die be­fore caus­ing any se­ri­ous harm be­cause hu­mans are dead-end hosts. Typ­i­cally, in­fected hu­mans do not need med­ical at­ten­tion be­cause the ju­ve­niles die after a few weeks or months. The most se­ri­ous neg­a­tive im­pact of A. braziliense on hu­mans comes from in­fect­ing their pets. In­fected cats and dogs re­quire ex­pen­sive med­ical at­ten­tion to stop the spread of the par­a­site. (Bal­four, et al., 2002; Roberts and Janovy Jr, 2009)

• Negative Impacts
• injures humans
  • bites or stings
• causes or carries domestic animal disease

Con­ser­va­tion Sta­tus

As a par­a­site with only neg­a­tive af­fects on its hosts, A. braziliense has no con­ser­va­tion sta­tus.

• IUCN Red List

  Not Evaluated

• US Federal List

  No special status

• CITES

  No special status

• State of Michigan List

  No special status

Other Com­ments

The width of the cu­tic­u­lar stri­a­tion pat­terns of A. braziliense is 3.45 mi­crom­e­ters com­pared to 5.66 mi­crom­e­ters in A. cey­lan­icum. Males of A. braziliense have a tu­ber­cu­lar process that is found at the buc­cal cap­sule of the mouth, whereas this fea­ture is com­pletely ab­sent in other species, such as A. cey­lan­icum. (Traub, et al., 2007; Yoshida, 1971)

Con­trib­u­tors

Stephanie Chap­man (au­thor), Uni­ver­sity of Michi­gan-Ann Arbor, Heidi Liere (ed­i­tor), Uni­ver­sity of Michi­gan-Ann Arbor, John Marino (ed­i­tor), Uni­ver­sity of Michi­gan-Ann Arbor, Barry OCon­nor (ed­i­tor), Uni­ver­sity of Michi­gan-Ann Arbor, Renee Mul­crone (ed­i­tor), Spe­cial Pro­jects.

Ref­er­ences

Bal­four, E., A. Zalka, R. La­zova. 2002. Cu­ta­neous larva mi­grans with parts of the larva in the epi­der­mis. Cutis, 69: 368-370. Ac­cessed April 16, 2011 at http://​www.​ncbi.​nlm.​nih.​gov/​pubmed/​12041816.

Brand, A., J. Haw­don. 2004. Phos­pho­inosi­tide-3-OH- ki­nase in­hibitor LY294002 pre­vents ati­va­tion of An­cy­lostoma can­inum and An­cy­lostoma cey­lan­icum third-stage in­fec­tive lar­vae. In­ter­na­tional Jour­nal for Par­a­sitol­ogy, 34: 909-914. Ac­cessed April 16, 2011 at http://​www.​ncbi.​nlm.​nih.​gov/​pubmed/​15217729.

Bren­ner, M., M. Patel. 2003. Cu­ta­neous larva mi­grans: The creep­ing erup­tion. Cutis, 72: 111-115. Ac­cessed April 16, 2011 at http://​www.​ncbi.​nlm.​nih.​gov/​pubmed/​12953933.

Car­valho, R., J. Araujo, F. Braga, S. Fer­reira, J. Araujo, A. Silva, L. Frassy, C. Alves. 2009. Bi­o­log­i­cal con­trol of An­clyos­tomis in dogs using the ne­ma­tode-trap­ping fun­gus Monacrospo­rium thau­ma­sium in south­east­ern Brazil. Vet­eri­nary Par­a­sitol­ogy, 165: 179-183.

Costa, A., A. Gomez- Ruiz, E. Ra­belo. 2008. Iden­ti­fi­ca­tion of gen­der-reg­u­lated genes in An­cy­lostoma braziliense by real-time RT-PCR. Vet­eri­nary Par­a­sitol­ogy, 153: 277-284. Ac­cessed April 16, 2011 at http://​www.​ncbi.​nlm.​nih.​gov/​pubmed/​18358613.

Costa, A., R. Gasser, S. Dias, E. Ra­belo. 2009. Male-en­riched tran­scrip­tion of genes en­cod­ing ASPs and Ku­niz-type pro­tease in­hibitors in An­cy­lostoma species. Mol­e­c­u­lar and Cel­lu­lar Probes, 23: 298-303. Ac­cessed April 16, 2011 at http://​www.​ncbi.​nlm.​nih.​gov/​pubmed/​19646525.

Don, T., Y. Oksov, S. Lustig­man, A. Loukas. 2007. Saposin-like pro­tein from the in­tes­tine of the blood-feed­ing hook­worm, An­cy­lostoma can­inum. Cam­bridge Jour­nals, 134: 427-436. Ac­cessed April 16, 2011 at http://​www.​ncbi.​nlm.​nih.​gov/​pubmed/​17109779.

Granzer, M., W. Haas. 1991. Host-find­ing and host recog­ni­tion of in­fec­tive An­cy­lostoma can­inum lar­vae. In­ter­na­tional Jour­nal for Par­a­sitol­ogy, 21 (4): 429-440. Ac­cessed April 16, 2011 at http://​www.​ncbi.​nlm.​nih.​gov/​pubmed/​1917283.

Labarthe, N., M. Lucia Ser­rao, A. Fer­reira, N. Almeida, J. Guer­rero. 2004. A sur­vey of gas­troin­testi­nal helminths in cats of the met­ro­pol­i­tan re­gion of Rio de Janeiro, Brazil. Vet­eri­nary Par­a­sitol­ogy, 123: 133-139. Ac­cessed Feb­ru­ary 05, 2010 at http://​www.​ncbi.​nlm.​nih.​gov/​pubmed/​1917283.

Nor­ris, D. 1971. The mi­gra­tory be­hav­ior of the in­fec­tive-stage lar­vae of An­cy­lostoma braziliense and An­cy­lostoma tubae­forme in ro­dent paratenic hosts. The Jour­nal of Par­a­sitol­ogy, 57 (5): 998-1009.

Richey, T., R. Gen­try, J. Fitz­patrick, A. Mor­gan. 1996. Per­sis­tant cu­ta­neous larva mi­grans due to An­cy­lostoma species. South­ern Med­ical Jour­nal, 89 (6): 609-611. Ac­cessed Feb­ru­ary 16, 2010 at http://​journals.​lww.​com/​smajournalonline/​Abstract/​1996/​06000/​Persistent_​Cutaneous_​Larva_​Migrans_​Due_​to.​10.​aspx.

Roberts, L., J. Janovy Jr. 2009. Foun­da­tions of Par­a­sitol­ogy. New York, NY: Mc­Graw- Hill.

Stothard, P., D. Pil­grim. 2003. Sex-de­ter­mi­na­tion gene and path­way evo­lu­tion in ne­ma­todes. Bioes­says, 25 (3): 221-231.

Teix­eira-Car­valho, A., R. Fu­ji­wara, E. Stemmy, D. Oive, J. Damsker, A. Loukas, R. Cor­rea-Oliveira, S. Con­stant, J. Bethony. 2008. Bind­ing of ex­creted and/or se­creted prod­ucts of adult hook­worms to human NK cells in Neca­tor amer­i­canus-in­fected in­di­vid­u­als from Brazil. Amer­i­can So­ci­ety For Mi­cro­bi­ol­ogy, 76 (12): 5810-5816.

Traub, R., R. Hobbs, P. Adams, J. Behnke, P. Har­ris, C.A Thomp­son. 2007. A case of mis­taken iden­tity-reap­praisal of the species of canid and felid hook­works (An­cy­lostoma) pre­sent in Aus­tralia and India. Par­a­sitol­ogy, 134: 113-119.

Williamson, A., S. Lustig­man, Y. Oksov, V. Deu­mic, J. Plieskatt, S. Mendez, B. Zhan, M. Bot­tazzi, P. Hotez, A. Loukas. 2006. An­cy­lostoma can­inum MTP-1, an astacin-like met­al­lo­pro­tease se­creted by in­fec­tive hook­worm lar­vae, is in­volved in tis­sue mi­gra­tion. In­fec­tion and Im­munol­ogy, 74 (2): 961-967. Ac­cessed April 16, 2011 at http://​www.​ncbi.​nlm.​nih.​gov/​pubmed/​16428741.

Yoshida, Y. 1971. Com­par­a­tive stud­ies on An­cy­lostoma braziliense and An­cy­lostoma cey­lan­icum. I. The adult stage. The Jour­nal of Par­a­sitol­ogy, 57 (5): 983-989. Ac­cessed April 16, 2011 at http://​www.​ncbi.​nlm.​nih.​gov/​pubmed/​4851100.