A randomised controlled trial of the immunogenicity and safety of a formaldehyde-inactivated Coxiella burnetii vaccine in 8-week-old goats.

Coxiella burnetii causes Q fever in individuals exposed to infected ruminants. Vaccination in 3-4-month-old goats, has been reported to result in significantly greater reduction in C. burnetii shedding compared to goats vaccinated one month before breeding, the most commonly used strategy of controlling Q fever on infected intensively-managed herds. It is possible that an even greater reduction in the number of animals shedding C. burnetii could be achieved if vaccination were administered shortly after protection from colostrum antibodies wanes and animals become susceptible to infection with C. burnetii. This study aimed to evaluate the immunogenicity and safety of a formaldehyde-inactivated phase 1 C. burnetii vaccine in 8-week-old goats. Two injections, four weeks apart, elicited specific IgM and IgG responses in all vaccinated goats (n = 6), while no antibodies were detected in two control groups (n = 12). Swelling at the site of inoculation was observed in all the vaccinated and in 10/11 of the placebo-treated goats but receded after 3 weeks. Weight change and rectal temperatures were also comparable between vaccinated and control goats. The data indicated that this vaccine could be suitable for immunising 8-week-old goats, although further trials to determine level of protection against challenge are required.

A Concise Review of the Epidemiology and Diagnostics of Rickettsioses: Rickettsia and Orientia spp.

Rickettsioses are globally distributed and caused by the family Rickettsiaceae, which comprise a diverse and expanding list of organisms. These include two genera, Rickettsia and Orientia Serology has been traditionally the mainstay of diagnosis, although this has been limited by cross-reactions among closely related members and diminished sensitivity/utility in the acute phase of illness. Other techniques, such as nucleic acid amplification tests using blood specimens or tissue swabs/biopsy specimens, sequencing, and mass spectrometry, have emerged in recent years for both pathogen and vector identification. This paper provides a concise review of the rickettsioses and the traditional and newer technologies available for their diagnosis.

Ultrastructural and genetic evidence of a reptilian tick, Aponomma hydrosauri, as a host of Rickettsia honei in Australia: possible transovarial transmission.

In 1993, a novel rickettsia was isolated from the blood of inhabitants of Flinders Island, Australia, with acute febrile illnesses. This rickettsia was found to be a new species of spotted fever group (SFG) rickettsia, eventually named Rickettsia honei. The suspected ectoparasite vector of this rickettsia has yet to be identified. The purpose of this study was to evaluate the presence of this rickettsial species in a suspected tick vector, Aponomma hydrosauri, by DNA sequencing and electron microscopy (EM). Ticks collected from an Australian blue-tongued lizard on Flinders Island and a copperhead snake in Tasmania were demonstrated to be infected with R. honei by PCR, DNA sequencing, and EM. Rickettsiae were found in ultrathin sections of salivary glands, malpighian tubules, and midgut epithelial cells. In a previous study with a R. honei-infected tick from Flinders Island, rickettsiae were found in the nuclei of midgut epithelial cells, and EM also revealed the presence of rickettsiae in the cytosol of oocytes and immature eggs, suggesting transovarial transmission. These results implicate A. hydrosauri as a possible host of R. honei on Flinders Island and Tasmania and also provide evidence favoring transovarial maintenance of R. honei.