Tick-borne rickettsioses are caused by obligate intracellular bacteria belonging to the spotted fever group of the genus Rickettsia. These zoonoses are among the oldest known vector-borne diseases. However, in the past 25 years, the scope and importance of the recognized tick-associated rickettsial pathogens have increased dramatically, making this complex of diseases an ideal paradigm for the understanding of emerging and reemerging infections. Several species of tick-borne rickettsiae that were considered nonpathogenic for decades are now associated with human infections, and novel Rickettsia species of undetermined pathogenicity continue to be detected in or isolated from ticks around the world. This remarkable expansion of information has been driven largely by the use of molecular techniques that have facilitated the identification of novel and previously recognized rickettsiae in ticks. New approaches, such as swabbing of eschars to obtain material to be tested by PCR, have emerged in recent years and have played a role in describing emerging tick-borne rickettsioses. Here, we present the current knowledge on tick-borne rickettsiae and rickettsioses using a geographic approach toward the epidemiology of these diseases.

Update on Tick-Borne Rickettsioses around the World: a Geographic Approach

Q fever is a zoonotic disease considered as emerging or re-emerging in many countries. It is caused by Coxiella burnetii, a bacterium developing spore-like forms that are highly resistant to the environment. The most common animal reservoirs are livestock and the main source of infection is by inhalation of contaminated aerosols. Although the culture process for Coxiella is laborious, advances on the knowledge of the life cycle of the bacterium have been made. New tools have been developed to (i) improve the diagnosis of Q fever in humans and animals, and especially animal shedders, (ii) perform epidemiological studies, and (iii) prevent the disease through the use of vaccines. This review summarizes the state of the knowledge on the bacteriology and clinical manifestations of Q fever as well as its diagnosis, epidemiology, treatment and prevention in order to understand what factors are responsible for its emergence or re-emergence.

/pdf/is-q-fever-an-emerging-or-re-emerging-zoonosis-4zaf3b5fu7.pdf

Is Q Fever an emerging or re-emerging zoonosis?

Comparison of Coxiella burnetii Shedding in Milk of Dairy Bovine, Caprine, and Ovine Herds

The bacterium Coxiella burnetii has been detected in the fetal membranes, birth fluids and vaginal mucus, as well as in the milk and other excretions of several domestic mammals. The finding of C. burnetii in association with abortion, parturition and in the postpartum period has led to the hypothesis that C. burnetii causes a range of reproductive diseases. This review critically evaluates the scientific basis for this hypothesis in domestic mammals. The review demonstrates a solid evidence for the association between C. burnetii infection and sporadic cases of abortion, premature delivery, stillbirth and weak offspring in cattle, sheep and goats. C. burnetii induced in-herd epidemics of this complete expression of reproductive failure have been reported for sheep and goats, but not for cattle. The single entities occur only as part of the complex and not as single events such as generally increased stillbirth rate. Studies show that C. burnetii initially infects the placenta and that subsequent spread to the fetus may occur either haematogenous or by the amniotic-oral route. The consequences for the equine, porcine, canine and feline conceptus remains to the elucidated but that infection of the conceptus may occur is documented for most species. There is no solid evidence to support a hypothesis of C. burnetii causing disorders such as subfertility, endometritis/metritis, or retained fetal membranes in any kind of domestic animal species. There is a strong need to validate non-pathology based methods such as polymerase chain reaction for their use in diagnostic and research in relation to establishing C. burnetii as the cause of abortion and to adapt an appropriate study design and include adequate control animals when linking epidemiological findings to C. burnetii or when evaluating effects of vaccination in production herds.

/pdf/coxiella-burnetii-associated-reproductive-disorders-in-sdjb5913mp.pdf

Coxiella burnetii associated reproductive disorders in domestic animals--a critical review

Prevalence of Coxiella burnetii infection in domestic ruminants: A critical review

Occurrence, distribution, and role in abortion of Coxiella burnetii in sheep and goats in Sardinia, Italy.

A total of 1485 adult ticks were collected from mammalian hosts in south-eastern Sardinia, Italy, during the years 2007-2008 Ticks were identified and tested by PCR analysis for presence of Rickettsia species of the spotted fever group, Ehrlichia canis, Anaplasma phagocytophilum, Coxiella burnetii, Bartonella species and Leishmania species Among all tick species examined (Rhipicephalus sanguineus, Rhipicephalus turanicus, Rhipicephalus bursa, Rhipicephalus pusillus, Hyalomma marginatum marginatum, Haemaphysalis sulcata and Dermacentor marginatus), only Hyalomma marginatum marginatum produced negative results A total of 22 pools belonging to the three tick species Rhipicephalus sanguineus (09 %), Rhipicephalus turanicus (45 %) and Rhipicephalus pusillus (100 %) were positive for Rickettsia species, while a total of five pools belonging to Rhipicephalus sanguineus (009 %), Haemaphysalis sulcata (167 %) and D marginatus (78 %) were positive for E canis Five pools of Rhipicephalus turanicus (18 %) were positive for A phagocytophilum Positivity for C burnetii was found in seven pools belonging to three tick species: Rhipicephalus sanguineus (05 %), Rhipicephalus turanicus (03 %) and Haemaphysalis sulcata (44 %) Finally, four pools belonging to Rhipicephalus sanguineus (009 %), Rhipicephalus turanicus (07 %) and Rhipicephalus bursa (11 %) were positive for Bartonella species Leishmania species DNA was not detected in any of the tick pools examined Data presented here increase our knowledge on tick-borne diseases in Sardinia, and provide a useful contribution to understanding their epidemiology

/pdf/pathogens-and-symbionts-in-ticks-a-survey-on-tick-species-32u6y53da9.pdf

Pathogens and symbionts in ticks: a survey on tick species distribution and presence of tick-transmitted micro-organisms in Sardinia, Italy.

Detection of Rickettsia hoogstraalii, Rickettsia helvetica, Rickettsia massiliae, Rickettsia slovaca and Rickettsia aeschlimannii in ticks from Sardinia, Italy.

During 2009–2010, 161 tissue samples (142 placentas, 16 brains, and 3 livers) from aborted ovine fetuses on Sardinia Island, Italy, were tested for toxoplasmosis. Organs that showed a positive result by nested polymerase chain reaction (PCR) targeting the ITS1 region for Toxoplasma gondii were also amplified with 11 genetic markers (SAG1, 5′-SAG2, 3′-SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and Apico) and then subjected to PCR/RFLP for genetic typing. T. gondii DNA was found in 5 placentas, 14 brains, and 2 livers by PCR analysis and all isolates displayed Type II alleles at all 11 loci with all 11 markers. The results indicate that the Type II T. gondii is associated with ovine abortion.

/pdf/molecular-characterization-of-toxoplasma-gondii-type-ii-in-1wwxwoy4lf.pdf

Valentina Chisu

Papers

Occurrence, distribution, and role in abortion of Coxiella burnetii in sheep and goats in Sardinia, Italy.

Pathogens and symbionts in ticks: a survey on tick species distribution and presence of tick-transmitted micro-organisms in Sardinia, Italy.

Detection of Rickettsia hoogstraalii, Rickettsia helvetica, Rickettsia massiliae, Rickettsia slovaca and Rickettsia aeschlimannii in ticks from Sardinia, Italy.

Molecular characterization of Toxoplasma gondii Type II in sheep abortion in Sardinia, Italy

Rickettsia slovaca from Dermacentor marginatus ticks in Sardinia, Italy.