Presumptive tick paralysis in 2 American Miniature horses in the United States

RATIONALE

Tick paralysis has not been reported in horses in North America.

CLINICAL FINDINGS

Two American Miniature horses were examined for progressive weakness and recumbency. Numerous ticks (Dermacentor variabilis) were found on both horses. Horse 1 was recumbent (grade 5/5 gait deficit) on presentation, whereas Horse 2 was standing but ataxic (grade 4/5 gait deficit) and tetraparetic. Both horses had decreased tongue and tail muscle tone, and had normal spinal reflexes. Cerebrospinal fluid cytology was normal. Equine herpesvirus-1 testing was negative.

PERTINENT INTERVENTIONS

Ticks were removed within 24 hours of presentation. Both horses were treated topically with permethrin. Supportive care included fluid therapy, treatment for corneal ulceration, and frequent repositioning during recumbency.

OUTCOME

Within 48 hours of tick removal, both horses were neurologically normal.

CLINICAL RELEVANCE

Ours is the first reported case of presumptive tick paralysis in horses in North America. Although rare, tick paralysis should be considered in horses presented with acute-onset weakness progressing to recumbency.

Dracunculus infections in domestic dogs and cats in North America; an under-recognized parasite?

We reviewed 62 new cases and 18 published reports of Dracunculus infections in domestic dogs and cats to describe the epidemiology of this parasite in dogs and cats in North America. We collected host and parasite data when available, including age, sex, and breed of dog, nematode location in the host, and any clinical signs at presentation and/or description of the apparent lesion. For dogs, infections were noted in six of the AKC breed groups, but none was reported from the toy group or the miscellaneous breed class. Age of infected dogs ranged from 7 months to 19 years (median 4 years; average 5.3 years), and infection rates were similar in male and female dogs. Most nematodes were associated with the distal extremities, but worms were also found in the chest/thorax, abdomen, head, and flank. Although most infected dogs had a single worm, three dogs had two or more worms that were collected from multiple lesions. Three new cat cases, with similar lesions, presentations and seasonality, were detected in Alabama, North Carolina and Texas. Cases were reported from a wide geographic range throughout eastern North America, during every month of the year, but 72% of infections were diagnosed in the late winter to early spring (December to May). All collected worms were larvigerous females which cannot be identified to species based on morphologic characters. Thus, we attempted to amplify and sequence a portion of the cytochrome c oxidase subunit I (COI) gene for specific identification. Although 13 worms from 12 cases were available, sequences were obtained for only eight worms from seven cases. These eight worms were D. insignis, a common parasite of raccoons (Procyon lotor) and other primarily carnivorous mammals. Female worms are the most likely to be detected in dogs and cats because male worms do not emerge, parasites should be preserved in ethanol for molecular identification. Although this study used convenience sampling of available data, we found that the parasite is widespread throughout the eastern US and Canada and that Dracunculus infections in dogs are more common than is revealed in published literature. However, more research is needed to understand the epidemiology, including transmission route(s), prevalence, and distribution of this parasite.

Identification of Heterobilharzia americana infection in a dog residing in Indiana with no history of travel

CASE DESCRIPTION

A 1-year-old castrated male dog residing in Indiana was examined because of intermittent vomiting of 4 months' duration.

CLINICAL FINDINGS

The dog's condition did not resolve with medication. Diagnostic imaging revealed a possible partial obstruction at the ileocecal junction. An exploratory laparotomy was performed. The jejunum contained diffusely distributed, nodular, intramural lesions; 2 biopsy specimens were collected from representative lesions. The pancreas was grossly swollen, and pancreatitis was presumed present. No other abnormalities were observed in the abdomen. Histologic examination of the submitted biopsy specimens revealed infection with Heterobilharzia americana.

TREATMENT AND OUTCOME

After diagnosis, the dog was treated with fenbendazole suspension (48 mg/kg [21.8 mg/lb], PO, q 24 h) for 10 days. This treatment was subsequently repeated 11 and 80 days later. One week after the end of the last fenbendazole treatment, several H americana eggs were detected in a fecal sample via saline sedimentation, and the dog was given praziquantel (25 mg/kg [11.4 mg/lb], PO, q 8 h) for 2 days. No gastrointestinal signs were evident 4 months after that treatment.

CLINICAL RELEVANCE

The dog described in this report was the first autochthonous canine case of H americana infection in Indiana, to the authors' knowledge; this case has confirmed that the distribution of this parasite in the Midwestern United States is broader than previously known. Increased awareness of the distribution of H americana should aid veterinarians in early, noninvasive diagnosis and appropriate treatment of affected animals. Repeated treatments and recheck fecal examinations may be necessary when managing these cases.

Number of Grooming Partners Is Associated with Hookworm Infection in Wild Vervet Monkeys (Chlorocebus aethiops)

There are many known benefits of social grooming among primates, including maintenance of social relationships, removal of ectoparasites, and improved physiological condition. Recently, however, researchers have noted that social grooming and social contact may also present a significant cost by facilitating transmission of some parasites and pathogens. We investigated whether the number of social grooming partners varied based on infection status for gastrointestinal parasites. We used focal animal sampling and continuous recording to collect data on the number of grooming partners for known individual vervet monkeys (Chlorocebus aethiops). We collected non-invasive faecal samples and examined them using faecal flotation, faecal sedimentation, and immunofluorescence microscopy. We detected 6 parasites: Trichuris sp. (92%), hookworm (71%), spirurids (68%), Oesophagostomum sp. (84%), Strongyloides sp. (24%), and Entamoeba coli (92%). The number of grooming partners varied significantly based on infection with hookworm and sex. No significant relationships were detected for other parasites. Associations between host behavioural variation and some parasite taxa (specifically Trichuris, Oesophagostomum, and Entamoeba spp.) were impossible to explore due to an extremely high prevalence among hosts. This is the first report that we are aware of that has detected an association between social grooming behaviours and infection with hookworm.

Temporal patterns of human and canine Giardia infection in the United States: 2003-2009

Giardia protozoa have been suspected to be of zoonotic transmission, including transmission from companion animals such as pet dogs to humans. Patterns of infection have been previously described for dogs and humans, but such investigations have used different time periods and locations for these two species. Our objective was to describe and compare the overall trend and seasonality of Giardia species infection among dogs and humans in the United States from 2003 through 2009 in an ecological study using public health surveillance data and medical records of pet dogs visiting a large nationwide private veterinary hospital. Canine data were obtained from all dogs visiting Banfield hospitals in the United States with fecal test results for Giardia species, from January 2003 through December 2009. Incidence data of human cases from the same time period were obtained from the CDC. Descriptive time plots, a seasonal trend decomposition (STL) procedure, and seasonal autoregressive moving-average (SARIMA) models were used to assess the temporal characteristics of Giardia infection in the two species. Canine incidence showed a gradual decline from 2003 to 2009 with no significant/distinct regular seasonal component. By contrast, human incidence showed a stable annual rate with a significant regular seasonal cycle, peaking in August and September. Different temporal patterns in human and canine Giardia cases observed in this study suggest that the epidemiological disease processes underlying both series might be different, and Giardia transmission between humans and their companion dogs seems uncommon.

A small-scale survey of hantavirus in mammals from Indiana

In order to determine if hantaviruses were present in mice and other small mammals in Indiana (USA), small mammals were trapped in Brown, LaPorte, Tippecanoe and Whitley counties. Sixty-seven small mammals were trapped during August and September 1994. Sixty-three Peromyscus leucopus, one Microtus pennsylvanicus, one Zapus hudsonius and two Blarina brevicauda were captured and tested for hantaviruses. Six P. leucopus were found to have antibody to Sin Nombre virus (SN) by IgG ELISA, and a 139 bp fragment of SN-like hantavirus was amplified from five of them. All six of the positive P. leucopus were from LaPorte County. No other small mammals had evidence of infection with SN virus. This study presents the first report of Sin Nombre-like hantavirus in P. leucopus from Indiana.