Ehrlichia canis--the causative agent of a haemorrhagic disease of dogs?

Huxsoll, DL; Pk, Hildebrandt; Nims, RM; Ja, Ferguson; Walker, J S

doi:10.1136/vr.85.21.587

Cited by 30 publications

(18 citation statements)

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“…Rickettsiosis in dogs caused by E. canis was first reported in 1935 in Algeria and was later reported in southern India and other parts of Africa in the 1940s (9,31). Subsequently, E. canis was relatively unrecognized until it was associated with outbreaks of canine tropical pancytopenia in Singapore and Malaysia from 1963 to 1968 (51) and was identified as being the cause of an epizootic of canine tropical pancytopenia in U.S. military dogs stationed in Vietnam in late 1968 (17,36). E. canis infections have since been well documented in the United States, Israel, Brazil, and Vietnam (1, 3, 12, 16, 20-22, 36, 49), and serologic and/or molecular evidence of infection in temperate regions where Rhipicephalus sanguineus is commonly found, including Central and South America, the Caribbean, parts of Africa, southern Europe, and southeast Asia, has also been reported (2, 5-8, 15, 18, 19, 23, 32, 33, 41, 42, 44, 50).…”

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Genetic and Antigenic Diversities of Major Immunoreactive Proteins in Globally DistributedEhrlichia canisStrains

Zhang

Luo

Keysary

et al. 2008

Clin Vaccine Immunol

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The extent of knowledge regarding the diversity of globally distributed Ehrlichia canis strains has been limited to information gained from a few evolutionarily conserved genes. In this study, E. canis strains from the United States (strain Jake [US]), Brazil (strain São Paulo [BR]), and Israel (strain 611 [IS] and Ranana [IS-R]) were used to examine the antigenic and genetic diversities of four well-characterized major immunoreactive protein genes/proteins. gp36 and gp200 were the most divergent genes, and nucleotide substitutions in the gp36 tandem repeat region of the IS strain, but not the IS-R strain, resulted in two amino acid differences (S3P and P3T) in each nine-amino-acid repeat (epitope-containing region). DNA sequences of gp19 and gp140 were completely conserved in the US and BR strains, but differences were found in the Israeli strains, including two fewer tandem repeats in gp140 and a single amino acid substitution in gp19 from the IS strain. E. canis whole-cell lysates from each isolate were examined by Western immunoblotting using sera from naturally infected dogs from each country, and four major immunoreactive proteins (gp19, gp36, gp140, and gp200) were identified in each strain using protein-specific antisera. The US and BR strains exhibited highly conserved immunoreactive protein profiles, while some differences were identified in the IS strain. Sera from naturally infected Israeli dogs confirmed gene sequencing information, which demonstrated two distinct E. canis strains, defined by the gp36 gene. Conversely, gp19 was strongly reactive and present in all E. canis isolates. gp140 and gp200 were also present in all strains, although gp140 in the IS strain had two fewer tandem repeats and exhibited a smaller mass.

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confidence: 99%

Genetic and Antigenic Diversities of Major Immunoreactive Proteins in Globally DistributedEhrlichia canisStrains

Zhang

Luo

Keysary

et al. 2008

Clin Vaccine Immunol

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“…Animals infected only with Ehrlichia canis may not exhibit acute symptoms (12), but hemorrhagic forms of the disease may be fatal (14). In South Africa, dogs frequently become coinfected with both Babesia canis and E. canis.…”

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Novel Ehrlichia Genotype Detected in Dogs in South Africa

Allsopp

2001

J Clin Microbiol

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DNA samples from dogs presenting with symptoms suggestive of canine ehrlichiosis, but with no morulae detected on blood smears, frequently failed to give a positive reaction with a North American Ehrlichia canis-specific PCR assay targeting the 16S rRNA gene. We suspected the presence of a pathogen genetically different from North American E. canis, and we performed experiments to test this hypothesis. DNA from one canine blood sample was subjected to PCR with primers designed to amplify Ehrlichia (Cowdria) ruminantium ruminantium 16S and map1 genes. Amplicon sequencing yielded 16S and map1 sequences which were more closely related to other E. ruminantium sequences than to those of any other Ehrlichia species. Fifty canine DNA samples were subjected to a PCR assay, previously found to be Cowdria-specific, which targets the pCS20 gene. Thirty-seven (74%) gave a positive signal, and 16 (32%) also gave visible amplicons after gel electrophoresis, suggesting that this E. ruminantium organism is common in the Pretoria-Johannesburg area. The organism has not been isolated in culture, so we cannot definitively state that it was responsible for the canine ehrlichiosis symptoms, although the occurrence of several similar cases suggests this to be so. Most importantly, we also do not yet know whether the organism is infective for, or causes heartwater in, ruminants.

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“…1,2,[5][6][7] The association of E. canis with hemorrhagic disease in dogs was first described in 1969. 8 Diagnosis of canine in the early stage of infection is important to ensure early treatment and a good prognosis. 7 Dogs in the acute phase of the disease demonstrate dramatic improvement in hematologic and clinical responses 24-48 hours after therapy.…”

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PCR Detection of Acute Ehrlichia Canis Infection in Dogs

et al. 1996

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Abstract.A polymerase chain reaction (PCR)-based detection assay that specifically detected Ehrlichia canis in dogs with acute infections was developed. A region of the 16S ribosomal RNA gene of E. canis was targeted for PCR amplification and chemiluminescent hybridization (CH) with a complementary internal 287-base pair (bp) oligonucleotide probe. The CH improved the PCR assay sensitivity 1,000-fold as compared with visualization on ethidium bromide-stained agarose gels. The PCR assay with CH (PCRKH) detected as little as 30 fg of E. canis genomic DNA, the equivalent of approximately 150 E. canis organisms. The 495-bp product defined by the specific primers was not detected when genomic DNA from E. platys, E. chaffeensis, E. risticii, and E. equi were used in the PCR/CH assay. The PCR/CH assay was tested with unfractionated blood samples collected from 9 dogs experimentally infected with E. canis. The PCR/CH assay had greater detection sensitivity than did cell culture isolation (CCI) from infected blood. PCR/CH detected E. canis 7 days prior to CCI in 4 of 6 experimentally infected dogs. The results obtained with the PCR/CH assay otherwise consistently matched the results obtained by CCI. This PCR/CH assay is a rapid, sensitive, and specific method for E. canis detection with sensitivity comparable to or exceeding that of CCI. A diagnosis of E. canis using this PCR/CH assay can be made in 2 days as compared with 14 weeks for CCI. The PCR/CH assay appears to be an acceptable alternative or complement to current diagnostic techniques.Canine ehrlichiosis is a tick-borne disease caused by an obligate intracellular parasite, Ehrlichia canis, which resides and replicates within mononuclear cells.7 The organism has a global distribution, including the United States, northern and southern African countries, Europe, Southeast Asia, and India.1,2,5-7 The association of E. canis with hemorrhagic disease in dogs was first described in 1969.8 Diagnosis of canine in the early stage of infection is important to ensure early treatment and a good prognosis.7 Dogs in the acute phase of the disease demonstrate dramatic improvement in hematologic and clinical responses 24-48 hours after therapy.7 However, dogs in the chronic stage of the disease have a poor prognosis and may not improve following treatment. 7,11Currently, definitive diagnosis of canine ehrlichiosis is based on hematologic, biochemical, and serologic findings.7 However, the most clinically reliable method for diagnosis of canine ehrlichiosis is by serologic techniques such as immunofluorescent antibody test (IFA) and plate latex agglutination that detect E. canis serum antibodies.7 However, serologic tests have several disadvantages: IgM and IgG antibodies are not detectable until at least 1-3 weeks postinfection, and cross-reactions occur between Ehrlichia species. Both of these factors can sometimes make a differential diagnosis difficult. Alternatively, the use of cell culture isolation (CCI) to detect E. canis in blood from infected dogs is both sensitive and ...

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Ehrlichia canis--the causative agent of a haemorrhagic disease of dogs?

Cited by 30 publications

References 0 publications

Genetic and Antigenic Diversities of Major Immunoreactive Proteins in Globally DistributedEhrlichia canisStrains

Genetic and Antigenic Diversities of Major Immunoreactive Proteins in Globally DistributedEhrlichia canisStrains

Novel Ehrlichia Genotype Detected in Dogs in South Africa

PCR Detection of Acute Ehrlichia Canis Infection in Dogs

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