Francisella tularensis prevalence and load in Dermacentor reticulatus ticks in an endemic area in Central Europe

First molecular detection of Francisella tularensis in turtle (Testudo graeca) and ticks (Hyalomma aegyptium) in Northwest of Iran

Francisella tularensis, causative agent of tularemia, is a contagious zoonotic ailment. This study was aimed to molecularly detect F. tularensis in tortoise blood (n = 100) and ticks (n = 100) collected in the West Azerbaijan province, Iran suing a 16SrRNA gene of the Francisella genus through employment of the Nested-PCR technique. The identified ticks were s Hyalomma aegyptium by morphological analysis. Seven percent (with a 95% CI: 3.5%-13.75%) of animal blood samples yielded positive results for the presence of the Francisella. Meanwhile, the Francisella was identified in tick samples at a rate of fifteen percent (15%) (with a 95% CI: 9%-23%). The samples containing positive results were specifically classified as F. tularensis subsp. holarctica. The samples were taken from ticks belonging to the H. aegyptium species that were gathered in Oshnavieh, southern part of West Azerbaijan province, Iran. This research was aimed to validate the existence of F. tularensis in ticks found within the West Azerbaijan province. Consequently, it is vital to acknowledge the potential of these ticks to transmit the bacteria to both livestock and humans through tick bites in this specific area.

Epidemiologic and Epizootic Data of Tularemia in the Past and in the Recent History in Croatia

Tularemia is a zoonotic disease caused by Francisella tularensis. A large number of recent studies have provided an update on the disease characteristics and the distribution across Europe. In Croatia, most of the clinical cases, as well as the reports of the disease in animals, date from the 20th century. In that period, epidemic and epizootic research had given detailed information about endemic regions and their characteristics, including suspected animal hosts and vectors. The region along the middle course of the Sava River, called Middle Posavina, is described as an endemic region, i.e., a “natural focus” of tularemia, in Croatia. In the 21st century, cases of human tularemia are being reported sporadically, with ulceloglandular, oropharyngeal and typhoid forms of disease. A majority of the described cases are linked with the consumption of contaminated food or water. The disease outbreaks still occur in areas along the course of the river Sava and in northwest Croatia. In this review article, we have summarized epidemiologic and epizootic data of tularemia in the past and in recent Croatian history.

PCR Based Prevalence Study of Francisella Tularensis in Kharkiv, Dnipropetrovsk, and Mykolaiv Oblasts during 2015-2018

INTRODUCTION

Tularaemia is a zoonotic disease caused by the gram-negative bacterium Francisella tularensis, which is endemic to Ukraine. The aim of this work was to provide screening of different field samples (rodent tails, ticks, pellets, water, and hay) to obtain an actual picture of the tularaemia epizootic situation in the Kharkiv, Dnipropetrovsk, and Mykolaiv oblasts.

MATERIAL AND METHODS

Samples were collected using the flag method (for ticks) and break-back traps (for rodents). Also, hay, water and owl pellets were collected for study. The F. tularensis genetic material in samples was detected using a 16S qPCR.

RESULTS

It was found that in Kharkiv oblast, 23% of collected samples were positive for F. tularensis, in Dnipropetrovsk oblast 1.9%, and in Mykolaiv oblast 0.4%.

CONCLUSION

Among the sample types, 34.7% of ticks, 1.8% of rodents, and 36.4% of pellets were positive for F. tularensis. The most frequent carriers of F. tularensis were the D. reticulatus and I. ricinus ticks (74.2% and 29.3%, respectively, of positive results).

Ecology of Francisella tularensis

Tularemia is a Holarctic zoonosis caused by the gamma proteobacterium Francisella tularensis and is considered to be a vector-borne disease. In many regions, human risk is associated with the bites of flies, mosquitoes, or ticks. But the biology of the agent is such that risk may be fomite related, and large outbreaks can occur due to inhalation or ingestion of contaminated materials. Such well-documented human risk factors suggest a role for these risk factors in the enzootic cycle as well. Many arthropods support the growth or survival of the agent, but whether arthropods (ticks in particular) are obligately required for the perpetuation of F. tularensis remains to be demonstrated. As with most zoonoses, our knowledge of the ecology of F. tularensis has been driven with the objective of understanding human risk. In this review, we focus on the role of the arthropod in maintaining F. tularensis, particularly with respect to long-term enzootic persistence.

Prevalence of Francisella tularensis in Dermacentor variabilis Ticks, Minnesota, 2017

Introduction: The prevalence of Francisella tularensis in Minnesota ticks is unknown. Ticks collected at seven sites were tested to determine the infection prevalence of F. tularensis in Dermacentor variabilis in Minnesota. Materials and Methods: Ticks were collected from two properties at an epizootic site and at five long-term tick research sites. Ticks were pooled by species, sex, date, and site with a maximum of 10 ticks per pool. Ticks were bisected and homogenized; DNA from supernatant was extracted and tested by real-time PCR (RT-PCR). Twice, additional ticks were collected for bacterial culture and isolation of F. tularensis. Proportion of positive pools and minimum infection rate (MIR) were calculated. Results: A total of 3527 ticks were tested for F. tularensis including 1601 male D. variabilis and 1926 female D. variabilis. Across all sites, 128 (34%) of 378 pools were RT-PCR positive for F. tularensis. Of 128 positive pools, F. tularensis from 96 (75%) was identified as type A; F. tularensis from 32 pools was unable to be subtyped. The overall MIR was 3.6%. The MIR was significantly lower at the epizootic site compared with Morrison County 1 (3.9% vs. 7.2%; p = 0.02) but did not differ between the epizootic site and Pine County 1 (3.9% vs. 2.1%; p = 0.49). Within the epizootic site, the MIR was significantly higher at Washington County 2 compared with the adjacent property (5.7% vs. 2.3%; p < 0.001). F. tularensis was cultured from 6 (15%) of 40 pools. Conclusions: F. tularensis was found in ticks at a majority of sites tested. The MIR of F. tularensis in D. variabilis ticks in Minnesota varied geographically. Our findings support the hypothesis that D. variabilis plays an important role in the natural history of tularemia in Minnesota. Further ecologic studies are needed to fully understand the importance of tick species in the maintenance and transmission of F. tularensis in Minnesota.

In Vivo Intradermal Delivery of Bacteria by Using Microneedle Arrays

Infectious diseases propagated by arthropod vectors, such as tularemia, are commonly initiated via dermal infection of the skin. However, due to the technical difficulties in achieving accurate and reproducible dermal deposition, intradermal models are less commonly used. To overcome these limitations, we used microneedle arrays (MNAs), which are micron-scale polymeric structures, to temporarily disrupt the barrier function of the skin and deliver a bacterial inoculum directly to the dermis of an animal. MNAs increase reliability by eliminating leakage of the inoculum or blood from the injection site, thereby providing a biologically relevant model for arthropod-initiated disease. Here, we validate the use of MNAs as a means to induce intradermal infection using a murine model of tularemia initiated by Francisella novicida We demonstrate targeted delivery of the MNA bolus to the dermal layer of the skin, which subsequently led to innate immune cell infiltration. Additionally, F. novicida-coated MNAs were used to achieve lethality in a dose-dependent manner in C57BL/6 mice. The immune profile of infected mice mirrored that of established F. novicida infection models, consisting of markedly increased serum levels of interleukin-6 and keratinocyte chemoattractant, splenic T-cell depletion, and an increase in splenic granulocytes, together confirming that MNAs can be used to reproducibly induce tularemia-like pathogenesis in mice. When MNAs were used to immunize mice using an attenuated F. novicida mutant (F. novicida ΔlpxD1), all immunized mice survived a lethal subcutaneous challenge. Thus, MNAs can be used to effectively deliver viable bacteria in vivo and provide a novel avenue to study intradermally induced microbial diseases in animal models.

Molecular survey on the occurrence of arthropod-borne pathogens in wild brown hares (Lepus europaeus) from Central Italy

Data about the spreading of arthropod-borne pathogens among hare populations are very scant, so the aim of the present preliminary study was to investigate, through molecular analysis, the occurrence of Anaplasma phagocytophilum, Bartonella sp., Borrelia burgdorferi sensu lato, Coxiella burnetii, Francisella tularensis, Leishmania spp. and piroplasms DNA in blood of 51 wild hares (Lepus europaeus) living in protected areas in Tuscany. All hares resulted negative for A. phagocytophilum, Bartonella sp., B. burgdorferi s.l., C. burnetii and F. tularensis. Five animals (9.8%) were positive for Leishmania and one hare (1.9%) tested positive for piroplasms. Sequencing of this sample showed a piroplasm similar to one Babesia isolate from the same animal species in Turkey. Therefore, to the best of our knowledge, this is the first molecular report of piroplasms occurring in wild hares from Italy, and the second worldwide. The examined hares appeared to be in good health status, corroborating the hypothesis of a chronic carrier state of some vector borne agents for this animal species.