Experimental transmission of Hepatozoon americanum to rodents

Johnson, Eileen; Allen, Kelly E.; Breshears, Melanie A.; Panciera, Roger J.; Little, Susan E.; Ewing, S. A.

doi:10.1016/j.vetpar.2007.10.017

Cited by 31 publications

(25 citation statements)

References 34 publications

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“…Hepatozoon species were present in 18 of 31 wild‐trapped cotton rats and 8 of 24 wild‐trapped mice with sequences 90.6 and 91.4% identical to reported H. americanum sequences, respectively 10 . Laboratory‐raised cotton rats and mice fed H. americanum oocysts became infected with cystozoites, 3 dormant forms of H. americanum , that were infectious for a dog 4 . Rats were not susceptible to infection.…”

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confidence: 89%

“…Conventionally, the mode of transmission to canids is assumed to be ingestion of oocysts within H. americanum ‐infected A. maculatum . Recently, an alternate pathway for transmission of H. americanum (Fig 1) was demonstrated 3–5 …”

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confidence: 99%

“…Because small rodents are preferred hosts for A. maculatum 6 we conducted both a field survey of small rodents for Hepatozoon infection 10 and experimental transmission trials of H. americanum using selected rodent species 3,4 . Hepatozoon species were present in 18 of 31 wild‐trapped cotton rats and 8 of 24 wild‐trapped mice with sequences 90.6 and 91.4% identical to reported H. americanum sequences, respectively 10 .…”

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confidence: 99%

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Alternate Pathway of Infection with Hepatozoon americanum and the Epidemiologic Importance of Predation

Johnson

Panciera

Allen

et al. 2009

Veterinary Internal Medicne

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Background: The range of American canine hepatozoonosis (ACH) is expanding from the southern USA northward. Transmission of Hepatozoon americanum occurs by ingestion of infected Gulf Coast ticks, Amblyomma maculatum. The source of the protozoan for the tick remains undetermined; infected dogs are unusual hosts for the tick.Objective: Compare possible sources of infection by field investigations of 2 multiple-dog outbreaks of ACH. Animals: Twenty-eight privately owned dogs (Canis familiaris), 1 coyote (Canis latrans), 31 wild-trapped cotton rats (Sigmodon hispidus), 24 wild-trapped field mice (Peromyscus leucopus), and 9 wild-caught rabbits (Sylvilagus spp.) from sites in eastern Oklahoma were monitored for hepatozoonosis. Six laboratory-raised cotton rats (S. hispidus), 6 Sprague-Dawley rats (Rattus norvegicus), 6 C57BL/6J-Lystbg-J/J mice (Mus musculus), 6 outbred white mice (M. musculus), 6 New Zealand white rabbits (Oryctolagus cuniculus), and 2 dogs were acquired through commercial vendors for experimental transmission trials of H. americanum.Methods: Four of 15 dogs in a rural neighborhood and 5/12 hunting Beagles were confirmed to be infected by blood smear examination, muscle biopsy, and polymerase chain reaction assay of the 18S rRNA gene of Hepatozoon species. Histories and tick host preferences led to field collections of common prey of canids and experimental transmission trials of H. americanum to selected prey (M. musculus, S. hispidus, R. norvegicus, and O. cuniculus).Results: Dogs with ready access to prey (4/15 dogs) or that were fed prey retrieved from hunts (5/12 hunting Beagles) became infected, providing evidence that predation is an important epidemiologic component of ACH infection. Experimental transmission studies identified a quiescent, infectious stage (cystozoite) of the parasite that provides an alternate mode of transmission to canids through predation, demonstrating that cotton rats, mice, and rabbits but not brown rats may act as paratenic hosts of H. americanum.Conclusions and Clinical Importance: Predation of prey harboring infected A. maculatum or containing cystozoites of H. americanum in their tissues provide 2 modes of transmission of ACH to dogs, putting unconfined dogs at increased risk of infection in endemic areas.

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Alternate Pathway of Infection with Hepatozoon americanum and the Epidemiologic Importance of Predation

Johnson

Panciera

Allen

et al. 2009

Veterinary Internal Medicne

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“…Alveolar endothelial cells (Davidson and Calpin 1976) were shown to be the host cell type in some cases. Cystozoites were not present in tissues from any of the infected cotton rats we studied; cystozoites have been reported in other prey animals, however, including amphibians (Smith and Desser 1998) and various rodents (Desser 1990;Johnson et al 2008b;Laakkonen et al 2001). These latent cystic forms (cystozoites) of Hepatozoon spp.…”

Section: Discussionmentioning

confidence: 64%

Light and transmission electron microscopic characteristics of a novel Hepatozoon spp. in naturally infected cotton rats (Sigmodon hispidus)

et al. 2009

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A novel species of Hepatozoon was recently reported in cotton rats (Sigmodon hispidus) collected from an area of Oklahoma where American canine hepatozoonosis is endemic. In this study, the various stages of merogony of the parasite were characterized by light and electron microscopy. Meronts occurred within parasitophorous vacuoles in hepatocytes and ranged from mononucleated spherical forms to large, mature forms in vacuoles that contained approximately 50 peripherally arranged merozoites. Developing merozoites had characteristic apicomplexan organelles, including anterior and posterior polar rings, a conoid, microtubules, rhoptries, micronemes, and a trilaminar membrane. As the meronts matured, numerous curvilinear merozoites budded from a residual body. This morphologic characterization extends our understanding of this novel Hepatozoon and adds information about the hepatozoa, apicomplexan parasites that infect numerous species.

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“…When cysts are infective cystozoites, vertebrates can be paratenic hosts (Landau et al 1972;Desser 1990;Paperna and Lainson 2004). Transmission occurs when paratenic hosts, such as anurans and rodents, are eaten by predators like crocodilians, snakes, and canids (Sloboda et al 2008;Johnson et al 2008Johnson et al , 2009. Smith et al (1994) transmitted Hepatozoon sipedon to Nerodia sipedon sipedon snakes via parasite cysts in the organs of northern leopard frogs Rana pipiens.…”

Section: Introductionmentioning

confidence: 99%

Anurans as paratenic hosts in the transmission of Hepatozoon caimani to caimans Caiman yacare and Caiman latirostris

et al. 2011

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Prevalence of Hepatozoon caimani has been reported in 76% of caimans Caiman yacare from the Pantanal region. Culex (Melanoconion) spp. mosquitoes were recently identified as natural vectors of this parasite. However, culicids are not typically eaten by crocodilians, suggesting that the main transmission route is through ingestion of insectivorous vertebrates, such as anurans. The susceptibility of wild frogs Leptodactylus chaquensis, Leptodactylus podicipinus and Scinax nasicus to infection by H. caimani was verified. Wild-caught anurans were force fed with sporulated oocysts from laboratory-bred Culex (Melanoconion) mosquitoes. Frogs were killed 30 days postinfection, and their internal organs were fed to caimans C. yacare and Caiman latirostris. Cystozoites were identified in fresh liver impression smears of L. chaquensis. C. yacare fed on anuran organ presented gametocytes in peripheral blood circulation between 74 and 80 days postinoculation (dpi). Gametocytes were also verified in C. latirostris fed on the internal organs of L. podicipinus and S. nasicus between 60-70 and 69-75 dpi, respectively. Since frogs used in experiment are sympatric with C. yacare and C. latirostris and may occur in the diet of these caimans, the results suggest these amphibians are paratenic hosts in the natural transmission cycle of H. caimani in Pantanal.

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Experimental transmission of Hepatozoon americanum to rodents

Cited by 31 publications

References 34 publications

Alternate Pathway of Infection with Hepatozoon americanum and the Epidemiologic Importance of Predation

Alternate Pathway of Infection with Hepatozoon americanum and the Epidemiologic Importance of Predation

Light and transmission electron microscopic characteristics of a novel Hepatozoon spp. in naturally infected cotton rats (Sigmodon hispidus)

Anurans as paratenic hosts in the transmission of Hepatozoon caimani to caimans Caiman yacare and Caiman latirostris

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