Tick-borne Diseases Research Articles

P-599. 6-Valent, OspA-Based VLA15 Lyme Disease Vaccine Candidate Against Lyme Borreliosis in a Healthy Pediatric and Adult Study Population: A Phase 2 Study Update

Abstract Background Lyme borreliosis (LB) is the most common tick-borne disease in the US, with approximately 476,000 cases diagnosed and treated annually and nearly 90 million individuals living in high incidence jurisdictions. Vector-focused prevention measures have varying levels of effectiveness due to low utilization, poor adherence, or high cost. A safe and efficacious vaccine to prevent LB is warranted. We provide an update on the Pfizer-Valneva VLA15 vaccine clinical development program, specifically the safety and immunogenicity booster data of the phase 2 trial (NCT04801420). Methods A randomized, observer-blinded, multi-centre Phase 2 study investigated the safety and immunogenicity of VLA15 in adult and pediatric study populations. A total of 625 participants aged 5-65 years were enrolled in three age groups (5-11 years, 12-17 years, and 18-65 years) and randomized 1:1:1 to receive VLA15 180 mcg with alum in a three-dose (Month 0-2-6) or a two-dose schedule (Month 0-6), or three injections of placebo (Month 0-2-6) followed by booster doses at Month 18 and Month 30. Safety and immunogenicity data up to one month after completion of the primary vaccination series and yearly booster doses are presented. Results Up to Month 19, VLA15 was safe and well tolerated in all age groups after all doses. Most adverse reactions were mild or moderate in severity. No related SAEs or other safety concerns were reported. The VLA15 booster dose induced a robust, anamnestic immune response against all six OspA vaccine serotypes in all age groups. Immune responses in children were higher than in adults across both schedules. Conclusion The Month 18 VLA15-221 booster dose was safe and immunogenic in both adults and children. The Month 30 booster data is under analysis. The ongoing blinded Phase 3 trials in Europe and North America will provide additional data which may support use of this vaccine as the primary preventative measure to protect against LB. Disclosures Marc D. Messier, PhD, SOBI: Advisor/Consultant|Valneva: employee|Valneva: Ownership Interest Laura Wagner, M.Sc., Valneva: employee Romana Hochreiter, PhD, Valneva Austria GmbH: WO2021/207615 A1|Valneva Austria GmbH: Employee, owner of stock options Erik Lamberth, MD, Pfizer: Employee|Pfizer: Stocks/Bonds (Public Company) Julian Larcher-Senn, PhD, Valneva: Advisor/Consultant Raphael Simon, PhD, Pfizer: Stocks/Bonds (Private Company) James groark, MD, Pfizer: Stocks/Bonds (Public Company) James H. Stark, PhD, Pfizer: Employee|Pfizer: Stocks/Bonds (Public Company)

P-351. Hospital associated outbreak of Crimean-Congo Hemorrhagic Fever, Dushanbe, Tajikistan, 2023

Abstract Background On July 1, 2023, a surgeon (Patient B) in Dushanbe, Tajikistan, died of acute febrile illness with hemorrhaging. Patient B had been hospitalized with acute respiratory distress four days before. Clinicians suspected Crimean-Congo Hemorrhagic Fever (CCHF). CCHF is a rare tick-borne disease. Tajikistan records just 1-6 cases annually. Patient B had no known exposures to ticks. We aimed to identify source and additional cases, and determine source.Figure 1.Timeline of CCHF Hospital Outbreak, Dushanbe, Tajikistan, 2023 Methods We conducted an outbreak investigation on July 1st. A confirmed case was defined as a person with a positive anti-CCHF IgM ELISA or RT-PCR and an epidemiological link. We reviewed medical charts to find contacts, defined as people who had been in direct contact with or had exposure to bodily fluids from any confirmed case in the last 21 days. We interviewed living cases and contacts and collected blood for testing. We also conducted an infection control assessment.Figure 2.Cases and contacts in CCHF Hospital Outbreak, Dushanbe, Tajikistan, 2023 Results A hospitalized adult (Patient A) had died of internal bleeding with extensive peritonitis (Figure 1) on June 16th. Six days later, a physician (Patient B) who had performed surgery on Patient A developed fever. Another six days later, he was hospitalized with hemorrhagic fever and diagnosed with CCHF within 3 days. Another physician (Patient C) who had performed surgery on Patient A was diagnosed with CCHF the following day. A laboratory assistant (Patient D) who had given a direct transfusion to Patient B was also diagnosed with CCHF the next day. Case-fatality rate was 25% (Table 1). We identified 29 healthcare providers who had contact to Patients A-D. All were tested, isolated and given oral Ribavirin 400 mg for 3 days as prophylaxis. None became ill (Figure 2). Interviews with hospital staff revealed infection control gaps, including lack of personal protective equipment during surgery and invasive procedures.Table 1.Characteristics of CCHF cases in a hospital outbreak in Dushanbe, Tajikistan, 2023 Conclusion Misdiagnosis and infection control gaps contributed to transmission of CCHF virus within the hospital. Direct blood transfusion is not a recommended practice, but performed due to lack of resources. Trainings were provided on infection prevention and control, and on CCHF diagnosis and care. No additional cases were detected. Disclosures All Authors: No reported disclosures

P-1330. Knowledge of Lyme Disease and Prevention Practices Among Parents of Pediatric Patients in a Lyme-Endemic Area

Abstract Background Lyme disease (LD) is a growing public health concern in the US that disproportionately affects children and the elderly. Studies have also found that minority groups are more likely to present with later, severe manifestations of LD, suggesting missed opportunities for early diagnosis and treatment. Despite the prevalence, few assessments have been performed to measure tickborne disease knowledge among parents in endemic areas, including social determinants of health.Table 1.Respondents with Spanish language preference, household income <$50,000, and highest education level of high school or below were more likely to misidentify the vector of Lyme disease or an image of the EM rash Methods An anonymous survey was conducted among parents/caregivers of patients at Stony Brook Children’s Hospital and its six ambulatory clinics in Long Island, NY (LI). The study was approved by the Stony Brook University Hospital IRB. Flyers were posted in patient rooms with QR codes linking to a Qualtrics™-based study, which displayed the informed consent statement and survey instrument. The flyers and survey were available in English and Spanish. Survey questions included demographics (income, level of education, etc), knowledge assessment (including identification of ticks as a vector and the erythema migrans (EM) rash), and tick bite prevention practices. Proportions were compared using χ2 tests. Results 78 respondents completed the survey, including 68 (87%) in English and 10 (13%) in Spanish. 12 (15%) reported living on LI for < 5 years, and 17 (22%) reported household income < $50,000, while 7 (9%) reported household income below $20,000. 21 (27%) reported highest level of education as high school. 18 (26%) did not correctly identify ticks as the vector for LD, while 14 (21%) did not correctly identify an EM. Respondents with Spanish preference, household income < $50,000, and highest education level of high school or below were more likely to misidentify the vector of Lyme disease or an EM image (Table 1). Conclusion Knowledge of LD remains limited, even in endemic areas. This is more pronounced in those with lower income, education, and Spanish preference. Culturally and linguistically appropriate public health outreach should focus on education about disease transmission and early recognition. Disclosures All Authors: No reported disclosures

Seroprevalence and Risk Factors of Anaplasma marginale in Water Buffaloes in Nile Delta of Egypt.

Bovine anaplasmosis is a major tick-borne disease in ruminants, resulting in significant economic loss for the dairy sector. This study aimed to evaluate the seroprevalence of Anaplasma marginale (A. marginale) in buffaloes in three governorates in Nile Delta of Egypt. A total of 400 serum samples from water buffaloes were examined using commercial cELISA kit. The overall seroprevalence of A. marginale was 12.5% and Kafr ElSheikh governorate has the highest seroprevalence rate (15.28%). The seroprevalence was higher in females (13.33%) than males with non-significant difference. Moreover, adult animals older than 8 years exhibited a significant risk for A. marginale seropositivity (22.92%), particularly during the summer (22.52%) and autumn (13.73%). Significant differences (P < 0.05) in seroprevalence rates were observed between tick-infested animals (14.96%) and those not treated with acaricides (17.7%), highlighting the influence of tick infestation and lack of acaricidal intervention on infection rates. The present study revealed the existence of antibodies against A. marginale in water buffaloes reared in Nile Delta of Egypt. Thus, the proper policies and control program should be adopted to reduce spreading of infection.

Congeneric Rodents Differ in Immune Gene Expression: Implications for Host Competence for Tick-Borne Pathogens.

Mice in the genus Peromyscus are abundant and geographically widespread in North America, serving as reservoirs for zoonotic pathogens, including Borrelia burgdorferi (B. burgdorferi), the causative agent of Lyme disease, transmitted by Ixodes scapularis ticks. While the white-footed mouse (Peromyscus leucopus (P. leucopus)) is the primary reservoir in the United States, the deer mouse (P. maniculatus), an ecologically similar congener, rarely transmits the pathogen to biting ticks. Understanding the factors that allow these similar species to serve as a poor and competent reservoir is critical for understanding tick-borne disease ecology and epidemiology, especially as climate change expands the habitats where ticks can transmit pathogens. Our study investigated immunological differences between these rodent species. Specifically, we compared the expression of six immune genes (i.e., TLR-2, IFN-γ, IL-6, IL-10, GATA-3, TGF-β) broadly involved in bacterial recognition, elimination, and/or pathology mitigation in ear biopsies collected by the National Ecological Observatory Network (NEON) as part of their routine surveillance. A principal components analysis indicated that immune gene expression in both species varied in two dimensions: TLR2, IFN-γ, IL-6, and IL-10 (comprising PC1) and TGF-β and GATA3 (comprising PC2) expression tended to covary within individuals. However, when we analyzed expression differences of each gene singly between species, P. maniculatus expressed more TLR2, IL-6, and IL-10 but less IFN-γ and GATA3 than P. leucopus. This immune profile could partly explain why P. leucopus is a better reservoir for bacterial pathogens such as B. burgdorferi.

Forest Fragmentation and Warmer Climate Increase Tick-Borne Disease Infection.

Anthropogenic disturbances degrade ecosystems, elevating the risk of emerging infectious diseases from wildlife. However, the key environmental factors for preventing tick-borne disease infection in relation to host species, landscape components, and climate conditions remain unknown. This study focuses on identifying crucial environmental factors contributing to the outbreak of severe fever with thrombocytopenia syndrome (SFTS), a tick-borne disease, in Miyazaki Prefecture, southern Japan. We collected data on SFTS case numbers, annual temperature and precipitation, species richness of large- and middle-sized mammals, forest perimeter length (indicating the amount of forest boundaries), percentage of agricultural land, human population, and sightseeing place numbers for each 25 km2 grid cell encompassing Miyazaki Prefecture. Through the construction of a model incorporating these factors, we found that longer forest perimeter and higher temperature led to a higher number of SFTS cases. Precipitation, mammal species richness, percentage of agricultural land, human population, and sightseeing point numbers had no effect on SFTS case numbers. In conclusion, climate condition and forest fragmentation, which increase the opportunity for human infection, played a pivotal role in SFTS outbreak.

Tick Diversity and Distribution of Pathogen in Ticks Collected from Wild Animals and Vegetation in Africa

Ticks are important vectors of a wide range of pathogens with significant medical and veterinary importance. Different tick species occupy different habitats with an overall widespread geographical distribution. In addition to their role as reservoirs or vectors, ticks are involved in maintaining pathogens in the environment and among wild and domestic animals. In this study, tick species infesting wild animals, as well as collected from the environment and their pathogens reported in 17 countries in Africa between 2003 and 2023, were collected according to the PRISMA guidelines. Data on ticks resulted in a total of 40 different tick species from 35 different wild animal species. Among the ticks, 34 infectious agents were noted including parasitic (Babesia, Theileria, Hepatozoon, Eimeria), bacterial (Anaplasma, Bartonella, Borrelia, Candidatus Midichloria mitochondrii, Candidatus Allocryptoplasma spp., Coxiella, Ehrlichia, Francisella, and Rickettsia), and a surprisingly high diversity of viral pathogens (Bunyamwera virus, Crimean-Congo Haemorhagic Fever virus, Ndumu virus, Semliki Forest virus, Thogoto virus, West Nile virus). These results highlight the public health and veterinary importance of the information on tick-borne infections. This knowledge is essential to strive to implement programs for sustainable control of ticks and tick-borne diseases.

Epidemiological and Clinical Study of Crimean–Congo Hemorrhagic Fever in Cattle and Humans in Maysan Province, Southern Iraq

Crimean-Congo hemorrhagic fever (CCHF) is a serious tick-borne zoonotic disease with significant public health concerns, particularly in regions like Europe, Asia, Africa, and the Middle East. In Iraq, sporadic outbreaks have been reported since 1979. This study examines the epidemiological and clinical characteristics of CCHF in humans and livestock in Maysan Province, Southern Iraq, focusing on the connection between human and cattle infections. The study utilized a retrospective approach, analyzing 34 human cases and 45 cattle infections through hospital records, patient interviews, and serological tests (ELISA). Results showed a higher prevalence among females (61.76%), with housewives being the most affected group (55.88%). Fever, body pain, and hemorrhagic symptoms were common. Cases peaked between May and August, mainly in Amarah District. In cattle, 84.44% tested positive for IgG antibodies, indicating past exposure, and 15.56% for IgM antibodies, suggesting recent infections. Tick density was notably higher in communal grazing areas, correlating with human infection hotspots. The study concludes that CCHF remains a significant threat in Maysan Province due to ecological and human-livestock interactions. Preventive strategies, including surveillance, public education, and tick control, are critical for reducing disease transmission. Further research is recommended to explore environmental and livestock roles in disease dynamics.

Haemaphysalis longicornis subolesin controls the infection and transmission of severe fever with thrombocytopenia syndrome virus

Severe fever with thrombocytopenia syndrome (SFTS) caused by the SFTS virus (SFTSV) is an emerging tick-borne disease with a high mortality rate. Haemaphysalis longicornis is the primary reservoir and vector of SFTSV. Here, we found that targeting subolesin (SUB), an anti-tick vaccine candidate, affects the infection and transmission of SFTSV in H. longicornis. RNAi-mediated knockdown of SUB repressed SFTSV infection in the salivary glands but not in the gut of H. longicornis, which may be associated with the modulation of protein processing in endoplasmic reticulum revealed by transcriptomic analysis. Knockdown of SUB decreased the survival and engorgement rates of ticks and impaired the horizontal and co-feeding transmission of SFTSV. Furthermore, active immunization with recombinant SUB inhibited the co-feeding transmission of SFTSV, although it had no significant effect on the blood-feeding behavior of infected ticks. Collectively, these results provide a potential target for controlling SFTS and other tick-borne viral diseases.

Insights into the contribution of multiple factors on Ixodes ricinus abundance across Europe spanning 20 years using different machine learning algorithms.

The interplay of biotic and abiotic factors driving Ixodes ricinus abundance trends are not fully understood. Machine learning (ML) approaches are being increasingly used to explore this and predict future abundance patterns of this species, however, the studies focusing on this to date have had limitations (including short study duration, limited sample size, narrow geographical range and use of a single ML model). This study was undertaken to address these limitations by applying 11 predictive ML models (across three data clustering techniques) to a large I. ricinus occurrence dataset (27,150 records) containing geographical and temporal data from a 20-year period across 30 European countries, coupled with data covering a range of climatic and habitat features (temperature, rainfall, Normalised Difference Vegetation Index (NDVI), percentage of discontinuous urban fabric and land use category). To assess which ML model was most suited to prediction of I. ricinus abundance, four performance metric values were calculated per model: Normalised Root Mean Square Error (NRMSE), Scatter Index (SI), Mean Absolute Percentage Error (MAPE) and R2, all of which describe the statistical relationship between predicted and actual I. ricinus abundance values. Furthermore, using a Random Forest (RF) model across three clustering methods, we determined which features most significantly impacted upon I. ricinus abundance. The study demonstrated that Agglomerative Hierarchical Clustering (AC) methods and Linear Regression (LR) modelling performed best with this dataset. Our findings revealed that land use and rainfall were the primary contributors to I. ricinus abundance, with temperature playing a lesser role. This was measured according to the extent of prediction error increase following exclusion of that factor from the analysis. We provide a summary of the factors most strongly linked to I. ricinus abundance, which can be used to guide interventions to aid the control of ticks and tick-borne disease across Europe.

Assessing tick attachments to humans with citizen science data: spatio-temporal mapping in Switzerland from 2015 to 2021 using spatialMaxent

BackgroundTicks are the primary vectors of numerous zoonotic pathogens, transmitting more pathogens than any other blood-feeding arthropod. In the northern hemisphere, tick-borne disease cases in humans, such as Lyme borreliosis and tick-borne encephalitis, have risen in recent years, and are a significant burden on public healthcare systems. The spread of these diseases is further reinforced by climate change, which leads to expanding tick habitats. Switzerland is among the countries in which tick-borne diseases are a major public health concern, with increasing incidence rates reported in recent years.MethodsIn response to these challenges, the “Tick Prevention” app was developed by the Zurich University of Applied Sciences and operated by A&K Strategy Ltd. in Switzerland. The app allows for the collection of large amounts of data on tick attachment to humans through a citizen science approach. In this study, citizen science data were utilized to map tick attachment to humans in Switzerland at a 100 m spatial resolution, on a monthly basis, for the years 2015 to 2021. The maps were created using a state-of-the-art modeling approach with the software extension spatialMaxent, which accounts for spatial autocorrelation when creating Maxent models.ResultsOur results consist of 84 maps displaying the risk of tick attachments to humans in Switzerland, with the model showing good overall performance, with median AUCROC values ranging from 0.82 in 2018 to 0.92 in 2017 and 2021 and convincing spatial distribution, verified by tick experts for Switzerland. Our study reveals that tick attachment to humans is particularly high at the edges of settlement areas, especially in sparsely built-up suburban regions with green spaces, while it is lower in densely urbanized areas. Additionally, forested areas near cities also show increased risk levels.ConclusionsThis mapping aims to guide public health interventions to reduce human exposure to ticks and to inform the resource planning of healthcare facilities. Our findings suggest that citizen science data can be valuable for modeling and mapping tick attachment risk, indicating the potential of citizen science data for use in epidemiological surveillance and public healthcare planning.Graphical

A customizable multiplex protein microarray for antibody testing and its application for tick-borne and other infectious diseases

Tick-borne infections are the most common vector-borne diseases in the USA. Ticks harbor and transmit several infections with Lyme disease being the most common tickborne infection in the US and Europe. Lack of awareness about tick populations, specific diagnostic tests, and overlapping signs and symptoms of tick-borne infections can often lead to misdiagnosis affecting treatment and the prevalence data reported especially for non-Lyme tick-borne infections. The diagnostic tests currently available for tick-borne diseases are severely limited in their ability to provide accurate results and cannot detect multiple pathogens in a single run. The multiplex protein microarray developed at Vibrant was designed to detect multiple serological antibodies thereby detecting exposure to multiple pathogens simultaneously. Our microarray in its present form can accommodate 400 antigens (molecules that can bind to specific antibodies) and can multiplex across antigen types, whole cell lysates, recombinant proteins, and peptides. A designed array containing multiple antigens of several microbes including Borrelia burgdorferi, the Lyme disease spirochete, was manufactured and evaluated. The immunoglobulin M (IgM) and G (IgG) responses against several tick-borne microbes and other infectious agents were analyzed for analytical and clinical performance. The microarray improved IgM and IgG sensitivities and specificities of individual microbes when compared with the respective gold standards. The testing was also performed in a single run in comparison to multiple runs needed for comparable testing standards. In summary, our study presents a flexible multiplex microarray platform that can provide quick results with high sensitivity and specificity for evaluating exposure to varied infectious agents especially tick-borne pathogens.

Experimental infection of wild boars (Sus scrofa) with Rickettsia rickettsii and evaluation of the transmission potential to Amblyomma sculptum ticks

BackgroundBrazilian spotted fever is a tick-borne disease caused by the bacterium Rickettsia rickettsii, whose main vector in Brazil is the tick Amblyomma sculptum. Amplifying hosts are essential for the perpetuation of this bacterium in the tick population as they can be sources of infection during bacteremic periods. Recent studies demonstrated the ability of suids (Sus scrofa) to sustain populations of A. sculptum, one of the main tick species found parasitizing wild boars in the midwestern and southeastern regions of Brazil. In this study, wild boars were experimentally infected with R. rickettsii by tick infestation and were evaluated for their ability to transmit the infection to A. sculptum ticks, under laboratory conditions.MethodsFour wild boars were infected with R. rickettsii through infestation with R. rickettsii-infected A. sculptum adults (infected group); a fifth wild boar was infested with uninfected A. sculptum adults (control group). Simultaneously, the animals were infested with uninfected larvae and nymphs of A. sculptum. The wild boars were monitored for 28 days by clinical examination and hematological tests, real-time quantitative PCR (qPCR) of blood for the detection of Rickettsia and inoculation of blood in guinea pigs. IgG antibody titers were followed until the end of the experiment. Unfed nymphs and adults, molted from engorged larvae and nymphs that fed on wild boars, were used to infest susceptible guinea pigs and rabbits; some of these unfed ticks were tested by qPCR for rickettsial detection.ResultsThe wild boars showed no clinical or hematological alterations, and bacteremia was not detected by qPCR or inoculation of wild boar blood into guinea pigs. Furthermore, wild boars showed a moderate humoral response, with anti-R. rickettsii endpoint titers up to 256 or 512. Rickettsial DNA was not detected in molted ticks after acquisition feeding on wild boars. Moreover, no disease or seroconversion was observed in guinea pigs and rabbits that were infested with ticks originated from wild boar acquisition feeding.ConclusionsWild boars seroconverted to Rickettsia spp. after being infested with R. rickettsii-infected A. sculptum; however, they did not develop bacteremia and did not act as competent amplifying hosts of R. rickettsii for A. sculptum ticks.Graphical

BABESIOSIS IN HUMANS

Babesiosis is a tick-borne parasitic disease caused by the intraerythrocytic protozoan Babesia spp. and transmitted primarily by Ixodes ticks. The geographical distribution of the parasites coincides with the regions where their tick vectors are prevalent. More than 50 cases of human babesiosis have been reported in Europe, mainly associated with Babesia divergens, which causes acute disease in cattle and is transmitted by Ixodes ricinus. In contrast, the incidence of the disease in the USA is approximately 2000 cases per year, with the main causative agent being Babesia microti and the tick vector being Ixodes scapularis. Although babesiosis is primarily an animal disease, humans can also become acutely ill, particularly splenectomized and immunocompromised individuals. Clinical manifestations range from asymptomatic to severe disease with symptoms including fever, chills, hemoglobinuria and anemia. There is a risk of potentially fatal complications such as acute respiratory, renal or multi-organ failure, particularly in vulnerable populations. Diagnosis is primarily based on light microscopy and PCR testing, while serological methods are more appropriate for epidemiological studies. Treatment regimens typically include a 7-10 day course of either atovaquone plus azithromycin or clindamycin plus quinine. Human cases are associated with outdoor activities or living in rural areas during the warm months when tick activity is at its peak. Because of the increasing incidence in endemic regions and the potentially serious clinical consequences, babesiosis should be considered in the differential diagnosis of febrile illnesses of unknown origin.

Ehrlichia Species in Dromedary Camels (Camelus dromedarius) and Ruminants from Somalia.

Ehrlichioses, caused by Ehrlichia species, are tick-borne diseases (TBDs) that affect animals and humans worldwide. This study aimed to investigate the molecular occurrence of Ehrlichia spp. in 530 animals (155 Dromedary camels, 199 goats, 131 cattle, and 45 sheep) in the Benadir and Lower Shabelle regions of Somalia. Blood DNA samples were tested for PCR targeting dsb and sodB genes of Ehrlichia spp. and PCS20 and map1 genes of E. ruminantium. The obtained sequences were submitted for phylogenetic analyses. Ehrlichia spp. were detected in 26.4% (140/530) of animals by dsb-PCR, with the highest prevalence in dromedary camels (54.8%), followed by cattle (29.8%), goats (7.0%), and sheep (4.4%). Dromedary camels, cattle, and goats had significantly higher infection odds compared to sheep (p < 0.05). Among dsb-PCR-positive samples, 76.9% (30/39) of cattle tested sodB-positive, while other species were negative. E. ruminantium was detected in 13.7% (18/131) of cattle by pCS20-PCR, but none were positive for the map1 gene. Phylogenetic analysis confirmed E. minasensis in camels, sheep, and goats and E. ruminantium in cattle, marking the first molecular evidence of E. minasensis in dromedary camels, sheep, and goats globally, and E. ruminantium in cattle from Somalia. These findings emphasize the need for further research on its economic and public health impact.

Modeling the Distribution of Dominant Hard Ticks in Southeastern Coastal Areas of the Caspian Sea.

Ticks are hematophagous arthropods that have direct and indirect effects on hosts, including the transmission of pathogens. An environmental suitability study of some vector species of hard ticks was conducted using the MaxEnt model in the south-eastern region of the Caspian Sea in Iran. The ticks were collected monthly (2014-2015) at 45 study sites covering different areas in terms of topography. Because most farms in the study area are traditionally engaged in sheep production and they are taken to pastures in the warm season, the ticks were sampled from herds of sheep. In total, 2410 hard ticks were collected and the vector species with wider distributions were considered for modelling. The areas under the curve for Hyalomma anatulicum, Hy. asiaticum, Hy. marginatum, Rhipicephalus bursa, Rh. sanguineus, and Rh. turanicus were 0.848, 0.762, 0.812, 0.772, 0.770 and 0.803, respectively. This means that temperature and precipitation were effective environmental variables for the prediction of appropriate regions for these tick species. The outputs of the models indicated that the western and south- western regions of Golestan Province provided the best niches for the presence of ticks. The western regions of Golestan Province are potential habitats for tick-borne diseases in both livestock and humans and special attention should be focused on preventing the spread of such diseases in this region.

Human neuroinvasive Toscana virus infections in Italy from 2016 to 2023: Increased incidence in 2022 and 2023.

BackgroundToscana virus (TOSV) is transmitted to humans through bites of infected sand flies. Neuroinvasive TOSV infections are leading causes of meningitis/encephalitis in southern Europe and notifiable in Italy since 2016. In 2022-23, Italy experienced extreme climate anomalies and a concomitant increase in mosquito and tick-borne disease transmission.AimTo identify the spatiotemporal distribution and risk groups of neuroinvasive TOSV infections in Italy in 2022-23 vs 2016-21.MethodsWe retrospectively described all autochthonous, laboratory-confirmed neuroinvasive TOSV cases notified to the national surveillance system in 2016-23 using frequencies, proportions, incidences and incidence risk ratios (IRRs) with 95% CIs, stratified by year, sex, age, region/autonomous province (AP) of infection/exposure and infection/exposure municipality by urbanisation level.ResultsIn 2022-23, 276 cases were notified (average annual incidence: 2.34/1,000,000 population) vs 331 cases in 2016-21 (0.92/1,000,000), with increased incidence extending into September. In 2022-23, infections were acquired in 12/21 regions/APs, predominantly in Emilia Romagna (57.6%; 159/276) as in 2016-21, including four regions/APs with no local infections in 2016-21. Similar to 2016-21, during 2022-23 residence in rural municipalities (vs urban), male sex, working age (19-67 years) and age > 67 years (vs ≤ 18 years) were identified as risk factors with IRRs of 2.89 (95% CI: 2.01-4.17), 2.17 (95% CI: 1.66-2.84), 5.31 (95% CI: 2.81-10.0) and 5.06 (95% CI: 2.59-9.86), respectively.ConclusionItaly experienced a nearly 2.6-fold increase in neuroinvasive TOSV incidence in 2022-23 vs 2016-21. Raising public awareness on risk factors and personal protection measures may enhance prevention efforts.

Modeling of periodic input Ornstein-Uhlenbeck temperature-tick-borne disease transmission coupling mechanism under climate change.

Given the rapid increase in climate change, investigating the impact of climate change on the transmission mechanism of tick-borne diseases is imperative. In order to fully capture the influence of the seasonal variation of temperature, environmental disturbances and the co-feeding transmission on the spread of tick-borne diseases, we propose a novel stochastic dynamical model that couples the mean-reverting Ornstein-Uhlenbeck temperature equation with periodic input to the tick-borne disease model. Through theoretical analysis, we derive sufficient conditions for the extinction of tick populations and the eradication of tick-borne diseases, as well as the stochastic persistence conditions of the system. In numerical simulations, we find that the periodic Ornstein-Uhlenbeck temperature equation can effectively fit the actual temperature data in low, medium, and high latitude regions of China. In risk assessment, we find that at the spatial perspective, low-latitude areas have a higher risk of tick-borne diseases, requiring enhanced control measures; from a temporal perspective, compared to the past, the current stage presents a greater risk of tick-borne diseases when preventive measures are not implemented. Additionally, we observe that larger noise of environment for tick populations favors the extinction of tick populations, while smaller temperature fluctuations, noise on infected hosts and ticks, as well as higher temperature regression rate, are more likely to lead to the extinction of tick-borne diseases. These findings provide crucial insights into understanding the impact of climate change on the transmission mechanism of tick-borne diseases.

Evaluation of Theileria equi vertical transmission rate and routes in a cohort of asymptomatic mares and their foals.

Equine piroplasmosis is a tick-borne disease mainly caused by Theileria equi and Babesia caballi. The objectives of this study were to analyse the frequency and routes of vertical transmission of these blood parasites from 179 asymptomatic mares to their foals. Foals were sampled within 72 h post-partum. The seroprevalences determined by Indirect Immunofluorescent Antibody Test (IFAT) and based on a subset sample of 107 couples, were 59.8% and 42.1% for T. equi and B. caballi, respectively in the mare population, and 54.2% and 40.2% in the foal population. A species-specific nested PCR was performed on all blood samples (358) and on available samples of placenta (24), umbilicus (6) and colostrum (18). For mares, 30.2% (54/179) and 2.2% (4/179) were PCR-positive for T. equi and B. caballi, respectively. Vertical transmission was not observed in the case of B. caballi, and four foals were born T. equi PCR-positive, giving a transmission rate of 7.4% (4/54). The blood smear evaluation showed viable T. equi parasites for the four foals without clinical signs of neonatal equine piroplasmosis, but one foal had acute renal failure. Theileria equi DNA was detected in umbilical cords, placenta and/or colostrum from PCR-positive mares, without correlation with the carrier status of the foal. One foal was born carrier but T. equi DNA had not been detected in the placenta. The 18S rRNA genotype E of T. equi was characterized in the four foals, foetal parts of the placenta and colostrum. The routes of transmission and particularly the possibility of colostral passage warrant further investigation.

Identification and analysis of the genetic diversity of Dermacentor everestianus using mitochondrial 16S rRNA and COI sequences in the Xizang Autonomous Region of China

Ticks serve as vectors and reservoirs for a variety of pathogens, including protozoa, bacteria, and viruses, that cause tick-borne diseases in both humans and livestock. Despite their widespread distribution, their genetic diversity and population structure in Xizang have not been thoroughly investigated. In this study, sheep ticks were identified from four counties by microscopy, followed by genetic analysis of Dermacentor everestianus populations in Xizang based on mitochondrial 16S rRNA and cytochrome oxidase subunit 1 (COI) gene sequences. D. everestianus was the predominant species and 16S rRNA gene sequence analysis revealed nine haplotypes with seven nucleotide variations, showing a mean haplotype diversity (Hd) of 0.505 and mean nucleotide diversity (Pi) of 0.00129. Similarly, the COI sequences revealed 28 haplotypes with 26 nucleotide variations, yielding a mean Hd of 0.828 and a mean Pi of 0.00279. Molecular variance analysis (AMOVA) indicated that most genetic variation occurs within populations. In addition, neutral test analyses suggested potential bottleneck events in the D. everestianus populations. The haplotype network had a star-like distribution with the common haplotypes A1, A2, B1, and B5. The phylogenetic tree separated haplotypes of both genes into two branches on the haplotype network indicating no distinct geographical clustering. This study is the first to highlight the prevalence of D. everestianus in Xizang, revealing moderate genetic differentiation among the four populations, possibly due to host mobility. This intensive investigation of genetic variation and population structure contributes valuable insights into the current population genetics of D. everestianus in Xizang, China.