Infectivity of Hepatozoon americanum cystozoites for a dog

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

doi:10.1016/j.vetpar.2008.02.026

Cited by 30 publications

(16 citation statements)

References 13 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%

“…Experimental transmission trials of H. americanum to laboratory‐raised cotton rats, mice, and white rats were conducted 3 . Cystozoite stages that were infectious for a dog 4 were found in multiple tissues of cotton rats and mice. Rats did not become infected.…”

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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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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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confidence: 99%

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confidence: 99%

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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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“…These latent cystic forms (cystozoites) of Hepatozoon spp. in the tissues of vertebrate hosts are often infective when ingested by predatory species (Desser 1990;Johnson et al 2008a). Conversely, infection has not been transmitted via ingestion of Hepatozoon meronts in tissues of infected animals (Nordgren and Craig 1984); absence of cystozoites suggests that cotton rats are not a direct source of infection for predators but rather transmit the parasite to a definitive arthropod vector that ingests circulating gamonts.…”

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confidence: 99%

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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Hepatozoon parasites (Apicomplexa: Hepatozoidae) in fish Hoplias aimara (Characiformes, Erythrinidae) from the Eastern Amazon, Brazil

et al. 2022

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Infectivity of Hepatozoon americanum cystozoites for a dog

Cited by 30 publications

References 13 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)

Hepatozoon parasites (Apicomplexa: Hepatozoidae) in fish Hoplias aimara (Characiformes, Erythrinidae) from the Eastern Amazon, Brazil

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