Anaplasma phagocytophilum infection in dogs: 34 cases (2000-2007)

Department of Veterinary Clinical Sciences, College of Veterinary Medicine, University of Minnesota, Saint Paul, MN 55108, USA.
Journal of the American Veterinary Medical Association (Impact Factor: 1.56). 07/2009; 234(12):1559-65. DOI: 10.2460/javma.234.12.1559
Source: PubMed


OBJECTIVE- To determine demographic characteristics of dogs from the upper Midwest infected with Anaplasma phagocytophilum and identify clinical and clinicopathologic abnormalities and response to treatment. DESIGN- Retrospective case series and owner telephone survey. ANIMALS- 34 dogs with granulocytic anaplasmosis. PROCEDURES- Records were reviewed for information on signalment, history, physical examination findings, clinicopathologic and serologic findings, and treatment. Owners were contacted by telephone within 4 months after dogs were discharged. RESULTS- Median age was 8 years. Distribution of month of diagnosis was bimodal, with 15 dogs examined during May or June and 11 others examined during October or November. Camping and hiking were the most frequently reported tick exposure activities. Lethargy (25/34) and anorexia (21/34) were the most common initial complaints, fever was the most common clinical sign (27/32), and thrombocytopenia was the most common clinicopathologic abnormality (21/22). Fifteen of 20 dogs were seropositive for antibodies against A phagocytophilum. Doxycycline was prescribed for 31 dogs, and clinical signs and fever resolved within 3 to 5 days. Median time for platelet count to return to reference limits was 7 days. No owners reported clinical sequelae when contacted after dogs were discharged. CONCLUSIONS AND CLINICAL RELEVANCE- Results suggested that granulocytic anaplasmosis should be suspected in dogs in endemic areas examined because of fever, lethargy, or thrombocytopenia, especially in dogs examined during the late spring or early fall. Treatment with doxycycline was successful in resolving clinical signs and thrombocytopenia.

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    • "Only one of the seropositive dogs had thrombocytopenia, the hallmark sign of acute CGA. Experimental studies have shown that thrombocytopenia is less frequently encountered in persistently infected dogs (Egenvall et al., 2000; Greig et al., 1996; Granick et al., 2009). "
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    ABSTRACT: Canine granulocytic anaplasmosis (CGA) is caused by the rickettsial microorganism Anaplasma phagocytophilum. CGA is typically characterized by fever, thrombocytopenia, lethargy, anorexia, arthropy, and other nonspecific clinical signs. Skin lesions have been described in naturally infected lambs and humans. The pathophysiology of CGA is not entirely clear, and the persistence of the organism after the resolution of clinical signs has been described. The aim of the study was to investigate if A. phagocytophilum can be detected in canine lesional skin biopsies from A. phagocytophilum-seropositive dogs with etiologically unclear skin lesions that improved after the treatment with doxycycline. Paraffin-embedded lesional skin biopsies were allocated into separate groups: biopsies from A. phagocytophilum-seropositive dogs responsive to treatment with doxycycline (n = 12), biopsies from A. phagocytophilum-seronegative dogs (n = 2), and biopsies in which skin lesions histopathologically resembled a tick bite (n = 10). The serological status of the latter group was unknown. Histology of the seropositive and seronegative dog skin lesions did not indicate an etiology. DNA was extracted, and a conventional PCR for partial 16S rRNA gene was performed. Anaplasma phagocytophilum DNA was amplified from 4/12 seropositive dogs’ skin biopsies. All sequences were 100% identical to the prototype A. phagocytophilum human strain (GenBank accession number U02521). Anaplasma phagocytophilum was not amplified from the 2 seronegative and 10 suspected tick bite dogs. Serum antibody titers of the PCR-positive dogs ranged from 1:200 to 1:2048. Histopathologically, a mild-to-moderate perivascular to interstitial dermatitis composed of a mixed cellular infiltrate and mild-to-moderate edema was seen in all seropositive dogs. In 8/12 seropositive dogs, vascular changes as vasculopathy, fibrinoid necrosis of the vessel walls, and leukocytoclastic changes were observed. In summary, our results support the hypothesis that the persistence of A. phagocytophilum in the skin may be causative for otherwise unexplained skin lesions in seropositive dogs.
    Full-text · Article · Apr 2014 · Ticks and Tick-borne Diseases
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    • "The clinical anaplasmosis case reported here is typical in its clinical presentation and laboratory abnormalities (Melter et al., 2007; Carrade et al., 2009; Granick et al., 2009; Mazepa et al., 2010; Canelas Domingos et al., 2011; Ravnik et al., 2011). Our diagnosis of A. phagocytophilum infection in this dog was based on the criteria described previously – suggestive clinical signs, morulae in the neutrophils , seropositivity, and positive PCR test (Carrade et al., 2009; Ravnik et al., 2011). "
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    ABSTRACT: Anaplasma phagocytophilum has been detected in ticks in Latvia; however, this is the first study to investigate this pathogen in dogs in Latvia. The aims of this study were: (i) to determine A. phagocytophilum seroprevalence in dogs, (ii) to correlate A. phagocytophilum seroprevalence in dogs with the geographic distribution of the tick species Ixodes ricinus and Ixodes persulcatus, and (iii) to determine if seroprevalence for A. phagocytophilum is higher in dogs with clinical signs suggestive of canine granulocytic anaplasmosis (CGA). Peripheral venous blood samples were collected from 3 dog groups: (i) clinically healthy dogs (HD, n=400), (ii) clinically healthy hunting dogs (HHD, n=41), and (iii) dogs with a clinical suspicion of anaplasmosis (SD, n=29). Sampling was carried out in regions inhabited by I. ricinus (IR), I. persulcatus (IP), and in regions where both tick species were present (M). SNAP 4Dx test (IDEXX) was used to detect antibodies against A. phagocytophilum in the blood of all dogs; nested PCR was performed in selected dogs of the SD group. Seroprevalence for A. phagocytophilum was calculated and correlated with the prevalent tick species in the region. A. phagocytophilum seroprevalence was 11.0% in HD, 12% in HHD, and 17% in SD with no significant differences among groups. In the IR region, seroprevalence was 12.5% (34/272) while seroprevalence in the M region was 17% (13/76), and both were significantly higher than the seroprevalence of 2% in the IP region (2/93; p<0.0005). One CGA case was diagnosed. We conclude that A. phagocytophilum seroprevalence in Latvia is within the range reported from other European countries. CGA should be included in the differential list in Latvian dogs with appropriate clinical signs and laboratory abnormalities, especially in I. ricinus habitat areas.
    Full-text · Article · Oct 2012 · Ticks and Tick-borne Diseases
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    ABSTRACT: Dogs and people are exposed to and susceptible to infection by many of the same tick-borne bacterial pathogens in the order Rickettsiales, including Anaplasma phagocytophilum, Ehrlichia canis, E. chaffeensis, E. ewingii, Rickettsia rickettsii, R. conorii, and other spotted fever group rickettsiae. Recent findings include descriptions of novel Ehrlichia and Rickettsia species, recognition of the occurrence and clinical significance of co-infection, and increasing awareness of Rhipicephalus sanguineus-associated diseases. Newer molecular assays are available, although renewed efforts to encourage their use are needed. This review highlights the ecology and epidemiology of these diseases, and proposes avenues for future investigation.
    No preview · Article · Mar 2010 · Trends in Parasitology
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