Granulocytic anaplasmosis in a horse from Nova Scotia caused by infection with Anaplasma phagocytophilum

A 16-year-old Paint stallion was presented with intermittent fever, inappetance, lethargy, icterus, distal limb edema, and submandibular lymphadenopathy. The horse was native to Nova Scotia and had never left that province. Morulae were detected in granulocytes. Ananaplasma phagocytophilum infection was confirmed by serology and polymerase chain reaction (PCR). The horse responded to treatment with oxytetracycline.     

Death of a horse infected experimentally with Anaplasma phagocytophilum

A 19-year-old horse that was one of a group of six horses infected experimentally with Anaplasma phagocytophilum for a study of the pathogenesis of equine granulocytic ehrlichiosis died suddenly two days after first showing clinical signs of disease. The clinical signs and laboratory findings observed before its death were similar to all those of the other infected horses, and to previous reports of this disease. A postmortem examination revealed widespread haemorrhaging in its internal organs, and vasculitis and thrombosis in the kidneys. These changes are consistent with disseminated intravascular coagulation, which has previously been reported in human beings infected with the presumably identical agent of human granulocytic ehrlichiosis.     

Upper respiratory signs associated with Anaplasma phagocytophilum infection in two horses

An adult Quarter Horse gelding (Case 1) was evaluated for tachypnoea and acute dysphagia. A 20-year-old Quarter Horse gelding (Case 2) was evaluated for respiratory stertor and severe, acute swelling of the head in the submandibular region. A physical examination, complete blood count, blood chemistry, upper airway endoscopy, and peripheral blood Anaplasma phagocytophilum polymerase chain reaction were completed for both horses. Both horses tested positive for A. phagocytophilum. The upper airway endoscopy for Case 1 revealed a feed contaminated pharynx, absent swallowing reflex, and left laryngeal hemiplagia. The upper airway endoscopy for Case 2 revealed severe diffuse pharyngeal swelling occluding the airway. Due to increased respiratory effort in Case 2, a tracheotomy was performed. In both horses, treatment consisted of intravenous oxytetracycline 6.6 mg/kg bwt i.v. q. 24 h for 2–3 days followed by minocycline 4 mg/kg bwt per os q. 12 h for 10–14 days. Both horses made full recoveries.     

Transplacental infection of a foal with Anaplasma phagocytophilum

This is the first report to document transplacental transmission of Anaplasma phagocytophillum in the horse. A 4-year-old late-term pregnant mare presented for a recent onset of pyrexia due to equine granulocytic anaplasmosis (EGA). She was hospitalised for treatment with oxytetracycline and monitoring of high-risk foaling due to significant thrombocytopenia. Parturition occurred overnight, and the foal was PCR positive for A. phagocytophilum at birth. The foal was slow to stand and nurse, with signs of neonatal encephalopathy and anaplasmosis (thrombocytopenia). Therapy with oxytetracycline resulted in complete clinical recovery of the mare and foal within 5 days. Congenital anaplasmosis should be considered in any foal delivered to a mare suffering from EGA during late-term pregnancy and guide appropriate antimicrobial therapy.     

Congenital infection with Anaplasma phagocytophilum in a calf in northern Germany

Anaplasma phagocytophilum is a Gram-negative, obligate intracellular tick-transmitted bacterium that replicates in neutrophils. It causes tick-borne fever (TBF) in sheep and cattle, but also elicits febrile disease in humans as well as in other domestic animals such as dogs, horses, and cats. Although increasingly recognized in Europe, the first laboratory-confirmed case of TBF in cattle from Germany has been published only recently. We here present the unusual case of an intrauterine transmission of A. phagocytophilum in a calf from northern Germany. To our knowledge, this is the first report of such an event occurring under field conditions in cattle.     

Postanesthetic recumbency associated with hyperkalemic periodic paralysis in a quarter horse.

Anesthesia and surgery in a Quarter Horse affected with hyperkalemic periodic paralysis resulted in euthanasia after 7 days of postoperative recumbency. Initial recovery was uneventful after extensive sinus surgery, but within 2 hours, the horse had severe muscle weakness. Plasma electrolyte concentrations were within the normal range during the period of recumbency. There was no clinical or laboratory evidence of severe muscle damage. Despite treatment with acetazolamide, isoproterenol, and intensive nursing, the horse was unable to stand for more than a few seconds and developed severe decubital ulcers. Ultrastructural examination revealed nemaline rods and swollen mitochondria in disrupted myofibers.     

Immune-mediated haemolytic anaemia and thrombocytopenia associated with Anaplasma phagocytophilum in a dog

A 10-year-old, crossbreed dog was presented with a history of severe lethargy, pyrexia and inappetence of several days' duration. Clinical examination revealed pallor of the mucous membranes, petechiae, generalised lymphadenopathy and effusions in multiple joints. Laboratory evaluation showed severe anaemia and thrombocytopenia, with positive in-saline agglutination and the presence of antiplatelet antibodies. The DNA of Anaplasma phagocytophilum, an endemic granulocytic rickettsial parasite, was detected by PCR. A poor response to doxycycline and immunosuppressive therapy with corticosteroids was seen. Euthanasia was performed after the development of disseminated intravascular coagulation. Postmortem examination demonstrated changes consistent with the development of disseminated intravascular coagulation and infection with granulocytic ehrlichiosis. This case documents the presence of canine granulocytic ehrlichiosis caused by A phagocytophilum in the U.K., and highlights the range of clinical signs and clinicopathological abnormalities that may be observed in infected dogs.     

Prophylactic use of dantrolene associated with prolonged postanesthetic recumbency in a horse

Dantrolene, a drug used in the prevention and treatment of malignant hyperthermia, was believed responsible for prolonged postanesthetic recumbency in a horse. Prophylactically, dantrolene was given orally before induction of anesthesia. Dantrolene has been recommended for use in horses at risk of developing postanesthetic myopathy. Side effects, including ataxia, may result from dantrolene administration.     

Seroprevalence of Anaplasma phagocytophilum infection in dogs in Germany

To determine the prevalence of Anaplasma phagocytophilum in dogs in Germany serum samples from 1124 dogs that were under suspicion of having anaplasmosis were examined. The samples were tested by an indirect immunofluorescence test (OFT) for antibodies to A. phagocytophilum. The geographical origin of positive cases were analysed with an geographic information system. Antibodies to A. phagocytophilum were found in 563 (50.1%) of the tested dogs. 166 dogs came from Saarland, 161 from North Rhine-Westphalia, 134 from Baden-Wuerttemberg, 33 from Bavaria, 22 from Rhineland-Palatinate, 11 from Hamburg, 10 from Brandenburg, 9 from Lower Saxony, 8 from Hesse and Berlin respectively and 1 from Schleswig-Holstein. Clinical signs and laboratory findings of 26 seropositive dogs were analysed. Those dogs showed a low haematocrit, thrombocytopenia and leucocytoses as well as higher values for alkaline phosphatase, ALAT und bilirubin. The clinical signs were lameness in 13 dogs, lethargy in 5, and uveitis in 3 dogs. Rhinitis and lymphadenopathy was found in 2 dogs and retinal detachment with blindness in 1 dog.     

Anaplasma phagocytophilum infection in a domestic cat in Finland: Case report

Background

Anaplasmosis is a vectorborne disease caused by the gram-negative bacterium Anaplasma phagocytophilum. This species displays positive tropism to granulocytes and can cause illness in several mammalian species, including cats, dogs, and humans. It is considered as an emerging disease in Europe. The clinical signs are nonspecific and include fever, lethargy, and inappetence. The most typical hematologic abnormality is thrombocytopenia. A tentative diagnosis can be made by detecting intracytoplasmic morulae inside neutrophils. The diagnosis is confirmed by PCR and serology in paired serum samples. A sample for PCR analysis should be taken before treatment. Anaplasmosis is treated with doxycycline.

Case presentation

A feline case of anaplasmosis is presented. The history, clinical presentation, diagnostics, treatment, and follow-up are discussed.

Conclusions

This case indicates that Anaplasma phagocytophilum infects cats in Finland. To provide accurate treatment, anaplasmosis should be listed as a differential diagnosis in cats suffering from acute febrile illness with previous tick exposure.     

Typical and atypical manifestations of Anaplasma phagocytophilum infection in dogs

Eighteen clinically ill dogs, naturally infected with Anaplasma phagocytophilum, were examined at a veterinary practice in Baxter, Minnesota. A clinical examination, complete blood cell count, enzyme- linked immunosorbent assay (ELISA) for A phagocytophilum, Borrelia burgdorferi, and Ehrlichia canis antibodies and Dirofilaria immitis antigen, and a polymerase chain reaction test for A phagocytophilum DNA were obtained for all dogs. Physical examination findings included fever, arthropathy, lymphadenopathy, epistaxis, acute gastritis, cervical hyperpathia, and central nervous system dysfunction. Complete blood cell count abnormalities included thrombocytopenia, morulae in neutrophils, anemia, leukopenia, eosinopenia, lymphopenia, and monocytosis. Seroreactivity to A phagocytophilum was found in 61%, B burgdorferi antibodies in 17%, and D immitis antigen in 5% of the dogs. Fever, arthropathy, neurologic dysfunction, and epistaxis are clinical syndromes that can be associated with A phagocytophilum infection. Treatment with doxycycline resulted in rapid resolution of clinical signs in all dogs.     

Anaplasma phagocytophilum infection (granulocytic anaplasmosis) in a dog from Vancouver Island

A 7-year-old Labrador retriever had nonspecific clinical signs that included lethargy, malaise, and difficult ambulation. The dog was native to Vancouver Island, British Columbia, and had never left this area. Morulae were identified in polymorphonuclear cells. Serologic studies and polymerase chain reaction (PCR) testing confirmed canine anaplasmosis caused by Anaplasma phagocytophilum. The dog recovered after treatment with tetracycline.     

Anaplasma phagocytophilum infection in a dog: identifying the causative agent using PCR

A diagnosis of Anaplasma phagocytophilum infection was confirmed in a two-year-old male golden retriever displaying few clinical and haematological abnormalities. This was achieved by demonstrating ehrlichial organisms in circulating neutrophils, by indirect immunofluorescence assay using A phagocytophilum as an antigen, and by detecting DNA specific for the 16S rRNA gene of granulocytic Anaplasma by PCR. After treatment with doxycycline for 10 days the dog showed improvement and the laboratory values returned to normal.     

Prevalence of Anaplasma phagocytophilum infection and effect on lamb growth

Background

A major challenge in sheep farming during the grazing season along the coast of south-western Norway is tick-borne fever (TBF) caused by the bacteria Anaplasma phagocytophilum that is transmitted by the tick Ixodes ricinus.

Methods

A study was carried out in 2007 and 2008 to examine the prevalence of A. phagocytophilum infection and effect on weaning weight in lambs. The study included 1208 lambs from farms in Sunndal Ram Circle in Møre and Romsdal County in Mid-Norway, where ticks are frequently observed. All lambs were blood sampled and serum was analyzed by an indirect fluorescent antibody assay (IFA) to determine an antibody status (positive or negative) to A. phagocytophilum infection. Weight and weight gain and possible effect of infection were analyzed using ANOVA and the MIXED procedure in SAS.

Results

The overall prevalence of infection with A. phagocytophilum was 55%. A lower weaning weight of 3% (1.34 kg, p < 0.01) was estimated in lambs seropositive to an A. phagocytophilum infection compared to seronegative lambs at an average age of 137 days.

Conclusions

The results show that A. phagocytophilum infection has an effect on lamb weight gain. The study also support previous findings that A. phagocytophilum infection is widespread in areas where ticks are prevalent, even in flocks treated prophylactic with acaricides.     

Variant -and individual dependent nature of persistent Anaplasma phagocytophilum infection

Background

Anaplasma phagocytophilum is the causative agent of tick-borne fever in ruminants and human granulocytotropic anaplasmosis (HGA). The bacterium is able to survive for several months in immune-competent sheep by modifying important cellular and humoral defence mechanisms. Little is known about how different strains of A. phagocytophilum propagate in their natural hosts during persistent infection.

Methods

Two groups of five lambs were infected with each of two 16S rRNA gene variants of A. phagocytophilum, i.e. 16S variant 1 which is identical to GenBank no {"type":"entrez-nucleotide","attrs":{"text":"M73220","term_id":"148293","term_text":"M73220"}}M73220 and 16S variant 2 which is identical to GenBank no {"type":"entrez-nucleotide","attrs":{"text":"AF336220","term_id":"13325085","term_text":"AF336220"}}AF336220, respectively. The lambs were infected intravenously and followed by blood sampling for six months. A. phagocytophilum infection in the peripheral blood was detected by absolute quantitative real-time PCR.

Results

Both 16S rRNA gene variants of A. phagocytophilum established persistent infection for at least six months and showed cyclic bacteraemias, but variant 1 introduced more frequent periods of bacteraemia and higher number of organisms than 16S rRNA gene variant 2 in the peripheral blood.

Conclusion

Organisms were available from blood more or less constantly during the persistent infection and there were individual differences in cyclic activity of A. phagocytophilum in the infected animals. Two 16S rRNA gene variants of A. phagocytophilum show differences in cyclic activity during persistent infection in lambs.