Human ehrlichiosis is the second most common tick-borne disease reported in Tennessee after Rocky Mountain spotted fever. Two closely related ehrlichiae, Ehrlichia chaffeensis and Ehrlichia ewingii, are both causative agents of human disease and are transmitted by Amblyomma americanum, the lone star tick. Prevalence rates and distribution patterns of these pathogens among ticks in Tennessee are...

Although scrub typhus and murine typhus are well-described tropical rickettsial illnesses, especially in Southeast Asia, only limited evidence is available for rickettsia-like pathogens contributing to the burden of undifferentiated febrile illness. Using commercially available kits, this study measured immunoglobulin G (IgG) antibody seroprevalence for Coxiella burnetii, Ehrlichia chaffeensis,...

The agent of human granulocytic ehrlichiosis (HGE), Ehrlichia phagocytophila, and Ehrlichia equi probably comprise variants of a single Ehrlichia species now called the Ehrlichia phagocytophila genogroup. These variants share a unique 153-kDa protein antigen with ankyrin repeat motifs encoded by the epank1 gene. The epank1 gene was investigated as an improved target for PCR diagnosis of HGE com...

For many vector-borne organisms, dogs can be used as sentinels to estimate the risk of human infection. The objective of this study was to use dogs as sentinels for multiple vector-borne organisms in order to evaluate the potential for human infection with these agents in southeastern Brazil. Blood from 198 sick dogs with clinicopathological abnormalities consistent with tick-borne infections w...

Detection of vector-borne pathogens is necessary for investigation of their association with vertebrate and invertebrate hosts. The ability to detect Ehrlichia spp. within individual experimentally infected ticks would be valuable for studies to evaluate the relative competence of different vector species and transmission scenarios. The purpose of this study was to develop a sensitive PCR assay...

Lyophilized tissues of mice and blood of sheep, infected with either the Kümm, the Welgevonden or the Ball 3 stock of Cowdria ruminantium, remain infective to mice and sheep after storage at 4 degree C for 90 days. Freeze-dried tissues stored at -18 degrees C and -28 degrees C are still infective after 6 months and 2 years, respectively.

E. canis infection of the canine cell line DH82 is a routine in studies with this bacteria. A protocol for isolation of host cell free bacteria was developed based on the use of glass beads. Improvement of infection with E. canis isolated by this method was detected by real-time PCR.

An attempt to establish an inbred line of mice resistant to Cowdria ruminantium failed. First generation couples were constituted from those mice out of 100 males and 100 females that had survived infection with the Kümm stock of C. ruminantium and that were serologically negative to the indirect fluorescent antibody test. An attempt to establish 10 separate inbred lines by constituting next ge...

An epidemiological study of Ehrlichia canis infection in dogs in Peninsular Malaysia was carried out using molecular detection techniques. A total of 500 canine blood samples were collected from veterinary clinics and dog shelters. Molecular screening by polymerase chain reaction (PCR) was performed using genus-specific primers followed by PCR using E. canis species-specific primers. Ten out of...

Ten stocks of Cowdria ruminantium (Ball 3, Breed, Comoro, Germishuys, Kümm, Kwanyanga, Mali, Mara, Nonile and Welgevonden) were compared from a cross-immunity, serological and mouse pathogenicity point of view. They were found to differ in varying degrees. Except for the Ball 3, Comoro and Germishuys stocks that were similar but not identical, there was no pattern in the antigenic diversity of ...