Climate change implications for the distribution of the babesiosis and anaplasmosis tick vector, Rhipicephalus (Boophilus) microplus

Tick fever agents in dairy cattle from a tropical region subjected to different breeding systems: Parasitological, clinical, serological aspects and genetic diversity of Anaplasma marginale

This study aimed to evaluate the infection dynamics by TF agents in heifers from birth to first calving, in contact with R. microplus, correlating parasitological, serological and clinical aspects of the infection. We also evaluate the persistence of the infection by TF agents in cows raised with or without contact with R. microplus, and the genetic diversity of A. marginale. Three studies were performed. In the first, 15 Girolando heifers (15/16 Holstein × 1/16 Gyr) were used and monitored from birth until their first calving (start of lactation), totaling 28 months of monitoring. In study 2, cows between the 1st and 6th lactation, which were raised on Compost Barn during lactation and on pasture during the dry period, were evaluated. In study 3, cows from the 1st to 7th lactation that after the first calving had no more contact with the cattle tick were evaluated. The animals were evaluated for parasitological, clinical, serological aspects and genetic diversity of Anaplasma marginale. Calves raised on pasture in contact with R. microplus in a tropical region reached a TF agent positivity ≥75 % at 4 months of age. TF cases occurred mostly after weaning, between 3 and 8 months of age. There was a correlation in A. marginale bacteremia between qPCR and blood smear, but no correlation between bacteremia and iELISA. Calves exposed to ticks between 3 and 8 months of age tended not to develop clinical TF as adults, even when continually exposed to R. microplus. Serologic or molecular results for B. bovis and B. bigemina in cows should be interpreted with caution, as the presence of these agents in less than 75 % of the herd may not indicate enzootic instability. In addition, cows exposed to ticks during dry-off had infections with higher levels of A. marginale in the 5th and 6th lactations. On the other hand, cows that had no further contact with R. microplus after their first calving showed infections with higher A. marginale levels in the first lactation. The A. marginale msp4 genotypes reported herein are the ones previously reported in Brazil.

Seasonal dynamic of ticks infesting cattle (Bos indicus) farms in two provinces in Cambodia

Cattle tick infestations pose a significant threat to livestock health and productivity worldwide. These parasitic arthropods, feed on blood and may cause various diseases in cattle, such as anaplasmosis, babesiosis, ehrlichiosis, and theileriosis. The objective of this study is to understand the seasonal dynamic and distribution patterns of tick infesting cattle in Cambodia. A longitudinal tick survey was conducted from January to December 2023 in two cattle farms in the Takeo and Kampong Speu provinces. Ticks were collected directly from the animal hosts with fine-tip forceps or specialized tools such as tick twisters, and from the vegetation using a combination of dragging and flagging method. A total of 13,678 ticks were collected from 240 inspected cattle and 11,384 ticks were found from vegetation around the two farms. The most prevalent species was Rhipicephalus microplus complex (60.6%), while R. haemaphysaloides was recorded in small numbers (0.4%). Unidentified species represented 39% of the collected ticks, consisting of immature Rhipicephalus spp. In addition, one adult Rhipicephalus linnaei, 245 immatures of Haemaphysalis spp., and 11,138 larvae of Rhipicephalus spp. were collected using dragging and flagging methods. The results revealed significant seasonal differences in tick population dynamics across both provinces, with 60.24% in Kampong Speu and 57.09% in Takeo during the rainy season, compared to 39.76% and 42.91% during the dry season. Statistical analysis on questing activity showed no significant differences in tick density across different collection sites, times of the day and province. Our findings indicate a very high density of tick-borne pathogen vectors was observed on cattle in the two farms, which a poses potential risk to cattle productivity in Cambodia.

Spatial epidemiology of Tabanus (Diptera: Tabanidae) vectors of Trypanosoma

BACKGROUND

Trypanosoma are protozoa parasites that infect animals and can cause economic losses in cattle production. Trypanosoma live in the blood and are transmitted by hematophagous insects, such as flies in the genus Tabanus. Using ecological niche models, we explored the current geography of six common Tabanus species in Brazil, which are considered vectors of Trypanosoma vivax and Tr. evansi in the Neotropics.

METHODS

We used georeferenced data and biotic and abiotic variables integrated using a fundamental ecological niche modeling approach. Modeling results from six Tabanus species were used to identify risk areas of Trypanosoma transmission in Latin America accounting for area predicted, landscape conditions, and density of livestock. We performed Jaccard, Schoener, and Hellinger metrics to indicate the ecological niche similarities of pairs of Tabanus species to identify known and likely vectors overlapping in distribution across geographies.

RESULTS

Our results revealed significant ecological niche similarities for two Tabanus species (T. pungens and T. sorbillans), whereas T. triangulum and T. importunus have low ecological similarity. Ecological niche models predicted risk of Trypanosoma transmission across Neotropical countries, with the highest risk in southern South America, Venezuela, and central Mexico.

CONCLUSIONS

More than 1.6 billion cattle and 38 million horses are under a threat category for infection risk. Furthermore, we identified specific areas and livestock populations at high risk of trypanosomiasis in Latin America. This study reveals the areas, landscapes, and populations at risk of Trypanosoma infections in livestock in the Americas.

Modeling the spatial distribution and environmental factors of dominant ixodid tick species parasitizing cattle in northwest Ethiopia

Ticks are blood-feeding ectoparasites that transmit pathogens to animals and humans, ranking as the second most significant epidemiological agents next to mosquitoes. Ethiopia hosts seven genera and 60 species of ticks; however, our limited understanding of their spatial distribution and influencing factors hampers prevention and control efforts for ticks and tick-borne diseases. This study examined six predominant tick species in northwest Ethiopia: Amblyomma lepidum, A. variegatum, Hyalomma rufipes, Rhipicephalus decoloratus, R. evertsi, and R. praetextatus. Utilizing the MaxEnt model and QGIS, we identified key habitat factors influencing tick occurrence and mapped their potential distribution under current climate conditions. Our findings revealed that tick distribution and habitat suitability vary by species, all benefiting from precipitation during the coldest quarter, land cover, and densities of sheep and goats. The annual temperature range and mean diurnal range influenced the distribution of A. lepidum, A. variegatum, R. evertsi, and R. praetextatus, while cattle densities impacted A. variegatum, R. decoloratus, R. evertsi, and R. praetextatus. Habitat suitability for H. rufipes and R. decoloratus was influenced by the annual temperature range and mean diurnal range, respectively. Amblyomma lepidum and H. rufipes were primarily influenced by the mean temperature of the driest quarter, while A. variegatum, R. decoloratus, and R. evertsi were affected by the mean diurnal range and R. praetextatus by land cover. Amblyomma lepidum and H. rufipes preferred warmer lowland habitats, while A. variegatum, R. decoloratus, and R. evertsi thrived in the mid-highlands around Lake Tana, and R. praetextatus favored northeastern and northwestern lowlands. This study is the first to model tick distribution in Ethiopia, offering valuable insights into tick distribution and the risk of tick-borne diseases in northwest Ethiopia. We recommend further studies to incorporate additional environmental and human factors affecting tick populations, as well as diverse modeling and evaluation methods, while enhancing the quantity and quality of tick occurrence data.

Assessment of the potential of a laser-based device as a Rhipicephalus microplus motility inhibitor

Rhipicephalus microplus is an ectoparasite responsible for causing economic losses in livestock farming totalling approximately $3.24 billion dollars per year. The main control method involves the use of chemical acaricides. However, the incorrect and intensive use of these chemicals has led to an increasing number of reports of resistance to acaricides. Therefore, the objective of this study was to develop and evaluate a laser prototype with a voltage of 5 V and power of 1000 mW to reduce the development of R. microplus. The methodology evaluated did not result in a high mortality rate; therefore, it was necessary to carry out a larval migration test. To carry out the test, 3 treatments were evaluated in triplicate (negative controls H20, 60% ethanol and positive control), with 20 larvae were evaluated for each replicate of the treatments, which resulted in an increase in the percentage of migration from 2.5% and 3.2% to above 94.9% and 93.5% in the negative controls, while in the positive control group there was no showed a significant change in migration, reaching close to 100%. This study demonstrated that physical control caused damage to ectoparasite locomotor structures and could affect the parasite's life cycle.

First evaluation of the efficacy and operational cost of acaricidal bath combining different droplet sizes, pressures and spray patterns in dairy cows naturally infested with Rhipicephalus microplus

Rhipicephalus microplus poses a significant challenge to animal health. This study evaluated efficacy and the effective operational cost (EOC) of different acaricidal treatments varying droplet size, pressure and spray pattern using a power sprayer. Three experiments were conducted on dairy cows, with each experiment involving three groups of 10 animals: two treated groups and one untreated control group. In the first experiment, acaricide treatments with the same droplet size (medium) were compared at different pressures (50 and 100 psi) using a full cone spray pattern: E1-M50 and E1-M100. In the second experiment, different droplet sizes (fine and medium) were compared at the same pressure (100 psi) using a full cone spray pattern: E2-F100 and E2-M100. The third experiment compared droplet sizes and spray patterns (fine at full cone and ultra coarse at flat fan) at the same pressure (100 psi): E3-F100 and E3-UC100. All animals received acaricide treatment on day 0 with a product based on organophosphate and pyrethroid. Tick counts were performed on days + 7, + 14, and + 21 to determine treatment effectiveness. Data on bath time were collected to determine the EOC, besides cost with acaricide, labor, water and electricity. No statistical differences (p > 0.05) regarding the mean tick count were observed between treated groups in all experiments. However, the highest efficacy values were found in treatments with larger droplets (medium and ultra coarse) and higher pressure (100 psi). In experiment 1, the efficacy varied from 70.6 to 88.9% and 75.2 to 93.7% for the treated groups E1-M50 and E1-M100, respectively. In experiment 2, efficacy varied from 48.7 to 86.2% for E2-F100 and from 68 to 94.7% for E2-M100. In experiment 3, efficacy ranged from 62.9 to 76.9% for E3-F100 and from 73.4 to 86.5% for E3-UC100. The EOC of the acaricide bath varied between 0.42 and 0.46 USD per animal. The findings show that treatment efficacy and EOC vary depending on the spray parameters used for the control of R. microplus, but further studies should be conducted to determine better combinations of pressure, droplet size and spray pattern.

What is the value of testing for tick-borne diseases in cattle in endemic areas? A case study of bovine anaplasmosis

Anaplasmosis is a tick-borne disease (TBDs) caused by Anaplasma spp. In areas where TBDs are endemic, it is crucial to consider the animals' immunological status in relation to these diseases. The true prevalence of bovine anaplasmosis, the percentage of animals with protective antibodies against this TBD, and the diagnostic characteristics of three tests (multiplex polymerase chain reaction (mPCR), competitive-inhibition enzyme-linked immunosorbent assay (cELISA), and blood smear (BS)) were estimated using a Bayesian approach. A total of 620 samples were collected in two subtropical areas of Ecuador. A significant finding of this study is that approximately 70% of cattle in those endemic areas harbored protective antibodies against Anaplasma marginale. This elevated percentage may stem from persistent exposure with a high pathogen prevalence in ticks. The decline in cELISA specificity must be attributed to cross-reactivity with protective antibodies against Anaplasma spp. It is crucial to interpret this test outcome alongside exposure history and clinical manifestations. The elevated apparent prevalence detected by cELISA and BS should be contextualized with mPCR results. The high seroprevalence and infrequent clinical outbreaks suggest that the pathogen has achieved endemic stability. This study provides valuable insights into the dynamics of anaplasmosis in endemic areas and may serve as a foundation for devising TBDs control strategies in these areas.

Molecular epidemiological survey of Babesia species infecting cattle in Paraguay

Paraguay, an agricultural country in South America, has a high prevalence of tick infestations in its cattle population due to warm temperatures, high humidity, and extensive grazing management practices. Consequently, Babesia infections, which are transmitted by ticks, might have a wide distribution in Paraguay, but the current status of these infections remains uncertain. Therefore, we aimed to assess the infection status of three clinically significant Babesia species, including Babesia bovis, Babesia bigemina, and Babesia naoakii, among cattle populations in Paraguay. Blood samples were collected from a total of 326 cattle across nine departments in Paraguay, and their DNAs were screened with species-specific PCR assays. Of the surveyed cattle, single infections of B. bovis and B. bigemina were detected in 24 (7.4 %) and 127 (39.0 %), respectively, while co-infection with both the parasite species was detected in 38 (11.7 %). In contrast, all of the surveyed cattle were negative for B. naoakii infection. The prevalence of B. bigemina-single infection was higher in the Eastern region (49.0 %) compared to the Western region (34.6 %), in cattle under extensive management (51.3 %) compared to those under semi-intensive management (34.6 %), and in Bos indicus cattle (50.3 %) compared to Bos taurus (15.8 %). Our findings demonstrated a wide distribution of B. bovis and B. bigemina infections among cattle in Paraguay, underscoring the importance of implementing effective control measures to reduce the potential economic losses associated with bovine babesiosis.

A reverse vaccinology approach identified novel recombinant tick proteins with protective efficacy against Rhipicephalus microplus infestation

The cattle tick, Rhipicephalus microplus, causes significant economic losses to the cattle industry. Tick control is predominately achieved via pesticide applications. However, alternative control methods such as vaccines are needed due to the tick's capacity to quickly develop pesticide resistance and to combat tick-borne diseases. We used an in silico reverse vaccinology approach to evaluate and rank open reading frames (ORFs) from the tick's transcriptome for their potential use as anti-R. microplus vaccine antigens. We manually annotated the 200 highest ranked antigens and selected 10 transcript ORFs as vaccine antigen candidates for expression in Pichia pastoris or insect cells. Six of the ten candidate antigens could be successfully expressed and purified in vitro as recombinant proteins with > 1 mg quantity. RT-PCR confirmed the expression of all six transcripts in tick RNA. However, only three of the six transcripts' corresponding ORFs could be confirmed as present in tick tissue protein extracts. Only four of the six vaccine candidate antigens were successfully expressed and purified in sufficient quantity (> 10 mg) for immunogenicity and efficacy trials in cattle. These four were designated BI-TS002, BI-TS004, BI-TS008, and BI-TS009 and sufficient annotation existed that showed sequence similarity to serine‑rich adhesin for platelets, glycine-rich cell wall structural membrane protein, SWM-1 tick serine protease inhibitor, and venom-like dermonecrotic toxins from ticks and spiders, respectively. Cattle immunized with BI-TS004, BI-TS008 and BI-TS009 yielded a statistically significant difference in antibody response post-immunization. This difference was noted on Days 42, 56, 70, and 84 post-immunization for BI-TS008 and BI-TS009, but only on Day 56 for BI-TS004. BI-TS008 and BI-TS009, were formulated with adjuvant and cattle stall tests conducted over a 175 day period to evaluate efficacy against R. microplus infestations. Both an adjuvant only negative control group and a positive control group using the commercially available GAVAC anti-tick vaccine were used. Efficacy was determined by comparing number of engorged adult female ticks, total egg mass weight, and egg hatchability produced from the immunized group to corresponding data from the adjuvant only negative control group. Thus, effects on engorged adult tick number, reproductive capacity, and fertility were measured. Both initial (designated Phase 1 and calculated from tick collections of Days 60-94 days post-first immunization) and long-term (designated Phase 2 and calculated from tick collections of Days 152-175 post-first immunization) efficacies were determined. The overall Phase 1 trial efficacies of BI-TS008, BI-TS009, and GAVAC were 68.3 %, 48.5 %, and 70.7 %, respectively. The overall Phase 2 trial efficacies of BI-TS008, BI-TS009, and GAVAC were 64.4 %, -30.1 %, and 45.1 %, respectively.

Beyond Human Babesiosis: Prevalence and Association of Babesia Coinfection with Mortality in the United States, 2015-2022: A Retrospective Cohort Study

Background

The prevalence of Babesia coinfecting tick-borne zoonoses and mortality outcomes are not fully elucidated. The objective of the present study was to determine babesiosis coinfection prevalence rates and estimate the association with severe disease and mortality.

Methods

We queried the TriNetX database between 2015 and 2022 for patients with babesiosis. The prevalence of Babesia coinfecting tick-borne zoonoses was estimated. The analysis focused on babesiosis coinfection with Borrelia burgdorferi, ehrlichiosis, and anaplasmosis. The exposure was coinfection, and the control group was the Babesia-only group. The primary outcome was 90-day mortality from the diagnosis of Babesia. Secondary outcomes were prevalence of coinfection, association of coinfection with acute respiratory distress syndrome, multiorgan failure, and disseminated intravascular coagulation. A multivariable logistic regression model was employed to estimate the disease severity and mortality risk associated with coinfections.

Results

Of the 3521 patients infected with Babesia, the mean age (SD) was 56 (18) years, 51% were male, and 78% were White. The frequency of overall malignancies, lymphomas, and asplenia was 19%, 2%, and 2%, respectively. Temporal distribution of coinfections followed the overall babesiosis pattern, peaking in the summer months. The prevalence of 1 or more coinfections was 42% (95% CI, 40%-43%). The rate of coinfection with Borrelia burgdorferi was the highest at 41% (95% CI, 39%-42%), followed by ehrlichiosis at 3.7% (95% CI, 3.1%-4.4%) and anaplasmosis at only 0.3% (95% CI, 0.2%-0.6%). Doxycycline was more likely to be prescribed in the coinfection group than the Babesia-only group (25% vs 18%; P < .0001). Overall, 90-day mortality was 1.4% (95% CI, 1.0%-1.8%). After adjusting for potential confounding factors, compared with the babesiosis-only group, the likelihood of 90-day mortality was lower in the coinfection group (adjusted odds ratio, 0.43; 95% CI, 0.20-0.91). Severe disease did not differ significantly between the 2 groups.

Conclusions

In this extensive study of >3000 patients with babesiosis in the United States, 4 in 10 patients had coinfecting tick-borne zoonoses. The prevalence rates of coinfection were highest with Borrelia burgdorferi, followed by ehrlichiosis, and lowest with anaplasmosis. Coinfection with other tick-borne infections was not associated with severe disease. It is plausible that this finding is due to the likelihood of treatment of coinfections with doxycycline. Future studies are needed to investigate the possible therapeutic benefits of doxycycline in babesiosis patients as, to date, no trials with doxycycline have been conducted in human patients with Babesia infections.

Tick fever agents in Holstein calves grazing in a tropical region: predisposing factors, impact on milk production, productivity, and role of Rhipicephalus microplus in epidemiology

The present study aimed to evaluate under dairy farm conditions the predisposing factors, impact on milk production and productivity, and the role of Rhipicephalus microplus in the epidemiology of tick fever agents in Holstein calves grazing in a tropical region. A total of 4292 pure female Holsteins were evaluated at a commercial farm. Until April 2020, calves had contact with R. microplus for between 3 and 24 months, while after April 2020, no animal had further contact with ticks. Three times a week the rectal temperature (RT) of all animals was determined, and blood samples were collected for evaluation of tick fever (TF) agents from those that showed RT >39.3 °C. Specific treatment was performed against Anaplasma marginale, Babesia bigemina and Babesia bovis when these TF agents were diagnosed in the blood smears. The number of relapses and treatments for TF agents were sub-classified into scales (1, 2, 3, 4, 5, 6 or 7-10 treatments or relapses, and animals that received blood transfusions). Within each sub-class, the health data of calves during lactation along with productivity data were analyzed. Based in the results, whether an animal received colostrum enriched with powdered colostrum substitute, whether the animal was an embryo transfer calf, and the weight at which each calf was weaned were ascertained as factors leading to more recurrences or treatments against TF agents in post-weaned calves. On average, each recurrence of TF agents that a heifer presented between three and seven months decreased milk production by 213.5 liters in the first lactation. Calves that received a blood transfusion had lower milk production at first lactation; lower weight at first fixed-time artificial insemination (FTAI); older age at first FTAI; older age at first, second, and third calving; and delayed age at third calving by 140 days compared to the farm average. R. microplus was the main agent causing clinical cases of TF on the farm, and 10,770 treatments against TF agents were carried out when calves aged between three and seven months had contact with this tick species (2018 and 2019). When the animals no longer had contact with ticks (2022 and 2023), there were no recurrences or treatments against TF agents despite the presence on the farm of S. calcitrans, which can maintain the transmission of A. marginale to the herd.

Geographical epidemiology of Hyalomma anatolicum and Rhipicephalus microplus in Pakistan: A systematic review

The livestock sector contributes almost 11% of Pakistan's GDP and is crucial to 35 million people's livelihoods. Ticks are a major economic threat, as over 80% of livestock, such as bovines, are tick-infested with Hyalomma and Rhipicephalus tick species. Hyalomma anatolicum and Rhipicephalus microplus are the most common tick species collected from livestock, transmitting primarily anaplasmosis, babesiosis, and theileriosis. We aimed to identify the geographical distribution of these two tick species and hot spot areas where the risk of these diseases being transmitted by these ticks is high. Following the PRISMA guideline, two authors conducted an independent review of literature sourced from various databases. We screened 326 research articles published between January 1, 1990, and December 31, 2023, focused on identifying the tick species at the district level. Thirty studies from 75 districts, representing 49.3% of the country's total area, detected at least one tick species through collection from animals. R. microplus was present in 81% (n = 61) and H. anatolicum in 82% (n = 62) of these sampled districts. We employed spatial and conventional statistical methods with Geographic Information Systems (GIS) after mapping the weighted distribution of both ticks (the number of ticks per standard unit of sampling effort). We identified northwestern and northcentral regions of the country as hotspots with the highest tick distribution, which aligned with the documented high prevalence of anaplasmosis, babesiosis, Crimean-Congo hemorrhagic fever (CCHF), and theileriosis in these regions. This underscores the urgent need for robust tick control measures in these districts to safeguard animal health and boost the livestock economy.

Vector abundance and associated abiotic factors that influence the distribution of ticks in six provinces of South Africa

Background and Aim

Climatic conditions significantly impact the life stages and distribution patterns of ticks and tick-borne diseases. South Africa's central plateau and various biomes offer a distinct landscape for studying the geography's effects. The study estimated tick species prevalence and the influential factors on their survival.

Materials and Methods

Ticks were gathered from communal cattle in South African provinces including Limpopo (LP), Gauteng (GP), Mpumalanga (MP), KwaZulu-Natal (KZN), the Eastern Cape (EC), and the Free State (FS), from September 2020 to November 2022. Using data from South African weathercasts, the annual climate was assessed.

Results

A total of 3,409 ticks were collected, with the highest infestation observed in KZN (45%), followed by LP (26%), EC (19%), GP (5%), MP (2%), and the FS (2%). The most prevalent tick species were Amblyomma hebraeum (55.1%), Rhipicephalus evertsi evertsi (13.9%) and Rhipicephalus (Boophilus), and decoloratus (11.9%). Other species included R. (Boophilus) microplus (10.85%), Hyalomma marginatum (4.8%), Rhipicephalus appendiculatus (1.4%), Harpalus rufipes (0.8%), Rhipicephalus exophthalmos (0.2%), Rhipicephalus glabroscutatus (0.2%), Rhipicephalus sanguineus (0.2%), Haemaphysalis silacea (0.5%), Ixodes pilosus (0.1%), and Rhipicephalus simus (0.1%). The infestations were most prevalent on farms in Pongola and KZN. The temperature fluctuated between 12°C and 35°C during data gathering, while humidity varied between 40% and 65%.

Conclusion

This study showed that ticks survive optimally in warm temperatures and high humidity conditions. Livestock farms with high tick infestations may be associated with several risk factors. These practices could involve suboptimal grazing, insufficient acaricidal treatment, and detrimental effects resulting from traditional animal husbandry. Future research is needed to longitudinally evaluate the effects of climate change on tick populations, pathogen transmission, hosts, habitats, and human behavior, influencing potential exposure risks.

Epidemiology of Anaplasma species amongst cattle in Africa from 1970 to 2022: A systematic review and meta-analysis

Tick-borne pathogens of the genus Anaplasma cause anaplasmosis in livestock and humans, impacting health and livelihoods, particularly in Africa. A comprehensive review on the epidemiology of Anaplasma species is important to guide further research and for implementation of control approaches. We reviewed observational studies concerning Anaplasma species amongst cattle in Africa. Peer-reviewed studies published in PubMed, Google Scholar, and Web of Science - from database inception to 2022 - were searched. The quality of individual studies was assessed using the Joanna Briggs Institute Critical Appraisal Tool and the pooled prevalences by diagnostic method were estimated using random-effects models. Heterogeneity across the studies was tested and quantified using the Cochran's Q statistic and the I2 statistic. Potential sources of heterogeneity were investigated by subgroup analysis. A total of 1117 records were retrieved and at the end of the screening, 149 records (155 studies) were eligible for this meta-analysis. The occurrence of Anaplasma species was reported in 31/54 countries in all regions. Seven recognised species (A. marginale, A. centrale, A. phagocytophilum, A. platys, A. capra, A. bovis, A. ovis) and nine uncharacterised genotypes (Anaplasma sp. Hadesa; Anaplasma sp. Saso; Anaplasma sp. Dedessa; Anaplasma sp. Mymensingh; Anaplasma sp. Lambwe-1; Candidatus Anaplasma africae; Anaplasma sp.; Candidatus Anaplasma boleense) were reported in African cattle. Anaplasma marginale was the most frequently reported (n=144/155 studies) and the most prevalent species (serology methods 56.1%, 45.9-66.1; direct detection methods 19.9%, 15.4-24.7), followed by A. centrale (n=26 studies) with a prevalence of 8.0% (95% CI: 4.8-11.9) and A. platys (n=19 studies) with prevalence of 9.7% (95% CI: 5.4-15.2). Anaplasma marginale, A. centrale and A. platys were reported in all Africa's regions, while A. ovis and A. capra were reported only in the northern and central regions. The uncharacterised Anaplasma taxa were mostly detected in the eastern and southern regions. Subgroup analysis showed that significant determinants for A. marginale exposure (serology) were geographical region (p=0.0219), and longitude (p=0.0336), while the technique employed influenced (p<0.0001) prevalence in direct detection approaches. Temperature was the only significant variable (p=0.0269) for A. centrale. These findings show that various Anaplasma species, including those that are zoonotic, circulate in African cattle. There is need for more genetic and genome data, especially for unrecognised species, to facilitate effective identification, improve livestock and minimise the health risk in human populations. Additional epidemiological data including pathogen occurrence, tick vectors and host range, as well as pathogenicity are essential.

Genetic factors underlying host resistance to Rhipicephalus microplus tick infestation in Braford cattle: a systems biology perspective

Approximately 80% of the world's cattle are raised in regions with a high risk of tick-borne diseases, resulting in significant economic losses due to parasitism by Rhipicephalus (Boophilus) microplus. However, the lack of a systemic biology approach hampers a comprehensive understanding of tick-host interactions that mediate tick resistance phenotypes. Here, we conducted a genome-wide association study (GWAS) of 2933 Braford cattle and found 340 single-nucleotide polymorphisms (SNPs) associated with tick counts. Gene expression analyses were performed on skin samples obtained from previously tick-exposed heifers with extremely high or low estimated breeding values for R. microplus counts. Evaluations were performed both before and after artificial infestation with ticks. Differentially expressed genes were found within 1-Mb windows centered at significant SNPs from GWAS. A total of 330 genes were related to the breakdown of homeostasis that was induced by larval attachment to bovine skin. Enrichment analysis pointed to a key role of proteolysis and signal transduction via JAK/STAT, NFKB and WNT/beta catenin signaling pathways. Integrative analysis on matrixEQTL revealed two cis-eQTLs and four significant SNPs in the genes peptidyl arginine deiminase type IV (PADI4) and LOC11449251. The integration of genomic data from QTL maps and transcriptome analyses has identified a set of twelve key genes that show significant associations with tick loads. These genes could be key candidates to improve the accuracy of genomic predictions for tick resistance in Braford cattle.

Characterization and Seasonal Dynamics of Tick Populations in Dairy Cattle Production Systems of Northwestern Colombian Amazon

Cattle ticks are a significant health concern in tropical livestock production due to their hematophagous behavior and potential as vectors for human and animal pathogens. In this study, we investigated the tick population present in dairy cattle production, calves, and grazing areas of livestock systems in the northwestern Colombian Amazon. Identification was based on taxonomic keys and molecular markers. Phylogenetic relationships were established using mitochondrial COX1 and 16S genes. Population structure analysis was performed considering age, racial type (B. indicus vs. B. taurus), and the influence of environmental factors and the geomorphological landscape on tick population dynamics. Our findings revealed the presence of a single tick species, with a unique haplotype identified for each mitochondrial gene assessed. Phylogenetic analysis classified the found species within Clade A of the Rhipicephalus microplus complex. Ticks were more prevalent during periods of low rainfall and high temperature, and B. taurus cows exhibited the highest tick abundance. Thus, these results provide insights into the population characteristics and distribution of the tick species present in dairy cattle production systems in the northwestern part of the Colombian Amazon. This information is fundamental for developing targeted strategies based on seasonal variation and host characteristics to mitigate tick infestation severity in the region.

High-resolution prediction models for Rhipicephalus microplus and Amblyomma cajennense s.l. ticks affecting cattle and their spatial distribution in continental Ecuador using bioclimatic factors

In Ecuador, the main tick species affecting cattle are Rhipicephalus microplus and Amblyomma cajennense sensu lato. Understanding their spatial distribution is crucial. To assess their distribution, data from 2895 farms visited between 2012 and 2017 were utilized. Ticks were collected during animal inspections, with each farm's location georeferenced. Bioclimatic variables and vapor pressure deficit data were obtained from Climatologies at High resolution for the Earth´s Land Surface Areas (CHELSA) dataset. They were overlaid to develop predictive maps for each species using Random Forest (RF) models. The cross-validation results for RF prediction models showed high accuracy for both R. microplus and A. cajennense s.l. presence with values of accuracy = 0.97 and 0.98, sensitivity = 0.96 and 0.99, and specificity = 0.96 and 0.93, respectively. A carefully selected subset of bioclimatic variables was used to describe the presence of each tick species. Higher levels of precipitation had positive effect on the presence of R. microplus but a negative effect on A. cajennense s.l. In contrast, isothermality (BIO3) was more important for the presence of A. cajennense s.l. compared to R. microplus. As a result, R. microplus had a broader distribution across the country, while A. cajennense s.l. was mainly found in coastal areas with evident seasonality. The coexistence of both species in some regions could be attributed to transitional zones, whereas high altitudes limited tick presence. This information can aid in developing appropriate tick management plans, particularly considering A. cajennense s.l.'s broad host range species and R. microplus's specificity for cattle. Moreover, the predictive models can identify areas at risk of associated challenging hemoparasite, requiring special attention and mitigation measures.

What is the optimal timing to initiate strategic control of Rhipicephalus microplus in taurine cattle in a tropical region?

Cattle tick control poses a significant challenge for livestock in tropical and subtropical regions. The objective of this study was to determine the most suitable timing to initiate a strategic tick control program and to identify the ideal number of acaricide treatments for adult taurine cattle (Bos taurus taurus) in a tropical region throughout the year. Three groups with 10 bovines each were performed: T01 (strategic treatment in late autumn/winter/late spring, every 28 days), T02 (strategic treatment to act in the "first tick generation" - early spring/summer/early autumn, every 28 days) and T03 (control). Tick counts (females 4-8 mm) were conducted every 14 days. If the tick burden in any group reached 30 or more during these counts, we applied an additional treatment. Over the course of a year, T02 required significantly fewer (p < 0.05) acaricide treatments than T01, with nine treatments for T02 and eleven for T01. Furthermore, during the tick counts, animals in T02 showed a lower tick burden compared to those in T01. Initiating the strategic tick control program in early spring, corresponding to the first tick generation, proved more effective than starting in autumn. This approach not only required fewer acaricide treatments but also resulted in a reduced tick burden. These benefits are particularly valuable in terms of animal welfare and managing acaricide resistance issues.

Worldwide comparison between the potential distribution of Rhipicephalus microplus (Acari: Ixodidae) under climate change scenarios

The cattle tick Rhipicephalus microplus (Acari: Ixodidae) has demonstrated its ability to increase its distribution raising spatially its importance as a vector for zoonotic hemotropic pathogens. In this study, a global ecological niche model of R. microplus was built in different scenarios using Representative Concentration Pathway (RCP), Socio-Economic Pathway (SSP), and a climatic dataset to determine where the species could establish itself and thus affect the variability in the presentation of the hemotropic diseases they transmit. America, Africa and Oceania showed a higher probability for the presence of R. microplus in contrast to some countries in Europe and Asia in the ecological niche for the current period (1970-2000), but with the climate change, there was an increase in the ratio between the geographic range preserved between the RCP and SSP scenarios obtaining the greatest gain in the interplay of RCP4.5-SSP245. Our results allow to determine future changes in the distribution of the cattle tick according to the increase in environmental temperature and socio-economic development influenced by human development activities and trends; this work explores the possibility of designing integral maps between the vector and specific diseases.

Predicting the distribution of Ixodes ricinus and Dermacentor reticulatus in Europe: a comparison of climate niche modelling approaches

BACKGROUND

The ticks Ixodes ricinus and Dermacentor reticulatus are two of the most important vectors in Europe. Climate niche modelling has been used in many studies to attempt to explain their distribution and to predict changes under a range of climate change scenarios. The aim of this study was to assess the ability of different climate niche modelling approaches to explain the known distribution of I. ricinus and D. reticulatus in Europe.

METHODS

A series of climate niche models, using different combinations of input data, were constructed and assessed. Species occurrence records obtained from systematic literature searches and Global Biodiversity Information Facility data were thinned to different degrees to remove sampling spatial bias. Four sources of climate data were used: bioclimatic variables, WorldClim, TerraClimate and MODIS satellite-derived data. Eight different model training extents were examined and three modelling frameworks were used: maximum entropy, generalised additive models and random forest models. The results were validated through internal cross-validation, comparison with an external independent dataset and expert opinion.

RESULTS

The performance metrics and predictive ability of the different modelling approaches varied significantly within and between each species. Different combinations were better able to define the distribution of each of the two species. However, no single approach was considered fully able to capture the known distribution of the species. When considering the mean of the performance metrics of internal and external validation, 24 models for I. ricinus and 11 models for D. reticulatus of the 96 constructed were considered adequate according to the following criteria: area under the receiver-operating characteristic curve > 0.7; true skill statistic > 0.4; Miller's calibration slope 0.25 above or below 1; Boyce index > 0.9; omission rate < 0.15.

CONCLUSIONS

This comprehensive analysis suggests that there is no single 'best practice' climate modelling approach to account for the distribution of these tick species. This has important implications for attempts to predict climate-mediated impacts on future tick distribution. It is suggested here that climate variables alone are not sufficient; habitat type, host availability and anthropogenic impacts, not included in current modelling approaches, could contribute to determining tick presence or absence at the local or regional scale.

Testing Efficacy of a Conserved Polypeptide from the Bm86 Protein against Rhipicephalus microplus in the Mexican Tropics

Rhipicephalus microplus economically impacts cattle production in tropical and subtropical countries. Application of acaricides constitutes the major control method; however, inadequate use has increased resistant tick populations, resulting in environmental and cattle product contamination. Anti-tick vaccines based on the Bm86 antigen are an environmentally friendly, safe, and economically sustainable alternative for controlling R. microplus infestations. Nevertheless, variable efficacy has been experienced against different geographic tick strains. Herein, we evaluated the efficacy of a conserved polypeptide Bm86 derived from a Mexican R. microplus strain previously characterized. Twelve cows were assigned to three experimental groups and immunized with three doses of the polypeptide Bm86 (pBm86), adjuvant/saline alone, and Bm86 antigen (control +), respectively. Specific IgG antibody levels were measured by ELISA and confirmed by Western blot. In addition, the reproductive performance of naturally infested R. microplus was also determined. The more affected parameter was the adult female tick number, with a reduction of 44% by the pBm86 compared to the controls (p < 0.05), showing a vaccine efficacy of 58%. Anti-pBm86 IgG antibodies were immunogenic and capable of recognizing the native Bm86 protein in the eggs, larvae, and guts of R. microplus. The negative correlation between antibody levels and the reduction of naturally tick-infested cattle suggested that the effect of the polypeptide Bm86 was attributed to the antibody response in immunized cattle. In conclusion, the polypeptide Bm86 showed a specific immune response in cattle and conferred protection against R. microplus in a Mexican tropical region. These findings support further experiments with this antigen to demonstrate its effectiveness as a regional vaccine.

Essential oil Ageratum conyzoides chemotypes and anti-tick activities

Rhipicephalus (Boophilus) microplus represents a significant obstacle to animal productivity in tropical and subtropical areas, leading to considerable economic losses for the dairy and meat production industries. Essential oils (EO) extracted from Ageratum conyzoides are known to cause death and induce morphogenetic abnormalities in several insect species. This plant, however, presents morphological flower variations, which range from white to purple, associated to different chemotypes. In this context, this study aimed to conduct a novel assessment on the effects of EO extracted from two A. conyzoides chemotypes in the control of the bovine tick R. microplus. The primary constituents of the oil obtained from white flower samples (WFs) were precocene I (80.4 %) and (E)-caryophyllene (14.8 %), while purple flower oil samples (PFs) contained predominantly β-acoradiene (12.9 %), γ-amorphene (12.3 %), α-pinene (9.9 %), bicyclogermacrene (8.9 %), α-santalene (8.7 %), and andro encecalinol (5.6 %). Interestingly, only the EO chemotype from A. conyzoides PFs displayed acaricidal activity towards R. microplus larvae, with an LC₅₀ of 1.49 mg/mL.

First Report of Rickettsia conorii in Hyalomma kumari Ticks

As a vector of wide range of pathogenic agents, ticks pose health threats to wild and domestic animals, and humans. Information is unavailable about the prevalence and spatial survey of Hyalomma kumari ticks and associated Rickettsia spp. in Pakistan. Concerning this knowledge gap, the present study aimed to molecularly detect Rickettsia species associated with H. kumari infesting small ruminants in Khyber Pakhtunkhwa (KP), Pakistan. A total of 409 H. kumari ticks were collected from 163/295 infested hosts with an infestation rate of 55.25%. A total of 204 females, 158 males, and 47 nymphs were collected. Goats were heavily infested by 224 ticks having an infestation rate of 58.33% (98/168), whereas sheep were infested by 185 ticks having a lesser infestation rate of 51.18% (65/127). Genomic DNA extracted from ticks was used for the amplification of tick (cox I, 16S rRNA, ITS-2) species and Rickettsia (gltA, ompA, and ompB) partial genes. Eighty-three ticks were subjected to PCR, and 8/83 (9.6%) were found positive for rickettsial agents. The cox I and 16S rRNA sequences of H. kumari showed 98.90-99.74% identity with H. kumari sequences reported from Pakistan, and phylogenetically clustered to the corresponding species reported from Pakistan and India. The obtained rickettsial gltA, ompA, and ompB sequences showed 100% identity with Rickettsia sp. of the Rickettsia conorii reported from Pakistan. In the phylogenetic trees, rickettsial sequences clustered with uncharacterized Rickettsia sp. from Pakistan and R. conorii from Israel, Russia, South Africa, and India. The present molecular based detection of H. kumari-associated R. conorii will facilitate effective surveillance in the region.

Microsclerotial pellets of Metarhizium spp.: thermotolerance and bioefficacy against the cattle tick

The cattle tick, Rhipicephalus microplus (Acari: Ixodidae), is a multi-billion dollar ectoparasite of global importance affecting beef and milk production. Submerged cultures of cosmopolitan entomopathogenic fungal species of the genus Metarhizium typically produce microsclerotia that provide both long-term survival and environmental resistance. Microsclerotia hold great potential as an unconventional active propagule to control this tick under laboratory and semi-field conditions. However, heat stress caused especially by elevated temperatures poses a critical environmental constraint for the successful development and efficacy of microsclerotia under tropical conditions. First, we screened six strains of Metarhizium anisopliae, Metarhizium robertsii and Metarhizium humberi for their ability to produce microsclerotia by submerged liquid cultivation. In addition, we assessed the biological fitness and bioefficacy of dried microsclerotial pellets under amenable (27 °C) and heat-stressed (32 °C) incubation against engorged adult females of R. microplus. Microsclerotia in pelletized formulation prepared with carriers based on diatomaceous earth and microcrystalline cellulose exhibited conidial production at different extents according to the fungal strain and the incubation temperature, but most strains displayed reduced sporogenesis when exposed to 32 °C. Engorged tick females exposed to sporulated microsclerotia from pelletized M. anisopliae CG47 or IP 119 had fewer number of hatching larvae in comparison to the control group, irrespective of the incubation temperature tested. The minimum dosage of microsclerotial pellets that effectively reduced hatchability of tick larvae was estimated to be 2 mg per plate (equivalent to 6.0 kg per hectare). Metarhizium microsclerotial pellets exhibited significant tolerance to 32 °C and pronounced acaricidal activity against this economically important ectoparasite of cattle, even under simulated environmental heat stress. KEY POINTS: • Heat stress affects conidial production by microsclerotia of most pelletized Metarhizium strains • Heat stress does not impair the acaricidal performance of pelletized microsclerotia • Pellet formulation of Metarhizium microsclerotia is a promising mycoacaricide.

Developing Anti-Babesia bovis Blood Stage Vaccines: A New Perspective Regarding Synthetic Vaccines

Bovine babesiosis is caused by the Apicomplexa parasites from the genus Babesia. It is one of the most important tick-borne veterinary diseases worldwide; Babesia bovis being the species associated with the most severe clinical signs of the disease and causing the greatest economic losses. Many limitations related to chemoprophylaxis and the acaricides control of transmitting vectors have led to the adoption of live attenuated vaccine immunisation against B. bovis as an alternative control strategy. However, whilst this strategy has been effective, several drawbacks related to its production have prompted research into alternative methodologies for producing vaccines. Classical approaches for developing anti-B. bovis vaccines are thus discussed in this review and are compared to a recent functional approach to highlight the latter’s advantages when designing an effective synthetic vaccine targeting this parasite.

Molecular characterization and genetic diversity of Babesia bovis and Babesia bigemina of cattle in Thailand

Babesia bovis and B. bigemina are the most common tick-borne parasites that cause bovine babesiosis which effects livestock production, leading to economic losses in tropical and subtropical areas of the world. The aims of this study were to determine the molecular detection, genetic diversity and antigenicity prediction of B. bovis based on spherical body protein 2 (sbp-2) gene and B. bigemina based on rhoptry-associated protein 1a (rap-1a) gene in cattle in Thailand. By PCR assay, the molecular detection of B. bovis and B. bigemina infection revealed levels of 2.58% (4/155) and 5.80% (9/155), respectively. The phylograms showed that B. bovis sbp-2 and B. bigemina rap-1a sequences displayed 5 and 3 clades with similarity ranging between 85.53 to 100% and 98.28 to 100%, respectively, when compared within Thailand strain. Diversity analysis of sbp-2 and rap-1a sequences showed 18 and 4 haplotypes, respectively. The entropy analysis illustrated 104 and 7 polymorphic sites of sbp-2 and rap-1a nucleic acid sequences, respectively, while those of sbp-2 and rap-1a amino acid sequences showed 46 and 4 high entropy peaks, respectively. Motifs analysis exhibited the distribution and conservation among sbp-2 and rap-1a sequences. The continuous and discontinuous B-cell epitopes have also been evaluated in this work. Therefore, our findings may be used to ameliorate the understanding inputs of molecular phylogeny, genetic diversity and antigenicity of B. bovis and B. bigemina Thailand stains.

Experimental vaccination in rabbits using the peptide RmS-17 antigen reduces the performance of a Mexican Rhipicephalus microplus tick strain

The tick vector Rhipicephalus microplus is considered one of the main problems in cattle production in tropical and subtropical regions. Anti-tick vaccines may form an alternative tick control method to the use of acaricides, and tick salivary proteins, such as Serpins, may be valuable as target antigens for developing anti-tick vaccines. In this study, we synthesized a recombinant peptide derived from Serpin RmS-17 protein using an Escherichia coli expression system and characterized the efficacy of the peptide RmS-17 for the control of R. microplus females infesting rabbits. Twelve New Zealand white rabbits were assigned to three experimental groups and vaccinated with three subcutaneous doses of the peptide RmS-17, recombinant R. microplus Bm86 antigen, and adjuvant/saline alone. The tick challenge was conducted with 120 R. microplus adults (60 females and 60 males) per animal, with the ticks placed inside a cotton sleeve glued to the back of the rabbit. Serum antibody levels (IgG) were assessed by ELISA and confirmed by Western blot; also, the reproductive performance of R. microplus was determined. The results showed that experimental vaccination in rabbits using the peptide RmS-17 antigen had a vaccine efficacy of 79% based on reductions in adult tick number, oviposition, and egg fertility compared to control animals. The peptide RmS-17 vaccinated rabbits developed a strong humoral immune response expressed by high anti-pRmS-17 IgG levels, and the Western blot analysis confirmed that it is immunogenic. The efficacy for the Bm86 vaccine was 62%, which is within the range of efficacy reported previously for Bm86 vaccine. The negative correlation between antibody levels and reduction in tick number strongly suggests that the effect of the vaccine was the result of the antibody response in vaccinated rabbits. In conclusion, this is the first study to evaluate the efficacy of the peptide RmS-17 against R. microplus tick infestation and show it to be immunogenic and protective in a rabbit model.

Jingmenviruses: Ubiquitous, understudied, segmented flavi-like viruses

Jingmenviruses are a group of viruses identified recently, in 2014, and currently classified by the International Committee on Taxonomy of Viruses as unclassified Flaviviridae. These viruses closely related to flaviviruses are unique due to the segmented nature of their genome. The prototype jingmenvirus, Jingmen tick virus (JMTV), was discovered in Rhipicephalus microplus ticks collected from China in 2010. Jingmenviruses genomes are composed of four to five segments, encoding for up to seven structural proteins and two non-structural proteins, both of which display strong similarities with flaviviral non-structural proteins (NS2B/NS3 and NS5). Jingmenviruses are currently separated into two phylogenetic clades. One clade includes tick- and vertebrate-associated jingmenviruses, which have been detected in ticks and mosquitoes, as well as in humans, cattle, monkeys, bats, rodents, sheep, and tortoises. In addition to these molecular and serological detections, over a hundred human patients tested positive for jingmenviruses after developing febrile illness and flu-like symptoms in China and Serbia. The second phylogenetic clade includes insect-associated jingmenvirus sequences, which have been detected in a wide range of insect species, as well as in crustaceans, plants, and fungi. In addition to being found in various types of hosts, jingmenviruses are endemic, as they have been detected in a wide range of environments, all over the world. Taken together, all of these elements show that jingmenviruses correspond exactly to the definition of emerging viruses at risk of causing a pandemic, since they are already endemic, have a close association with arthropods, are found in animals in close contact with humans, and have caused sporadic cases of febrile illness in multiple patients. Despite these arguments, the vast majority of published data is from metagenomics studies and many aspects of jingmenvirus replication remain to be elucidated, such as their tropism, cycle of transmission, structure, and mechanisms of replication and restriction or epidemiology. It is therefore crucial to prioritize jingmenvirus research in the years to come, to be prepared for their emergence as human or veterinary pathogens.

A Scoping Review of Species Distribution Modeling Methods for Tick Vectors

Background

Globally, tick-borne disease is a pervasive and worsening problem that impacts human and domestic animal health, livelihoods, and numerous economies. Species distribution models are useful tools to help address these issues, but many different modeling approaches and environmental data sources exist.

Objective

We conducted a scoping review that examined all available research employing species distribution models to predict occurrence and map tick species to understand the diversity of model strategies, environmental predictors, tick data sources, frequency of climate projects of tick ranges, and types of model validation methods.

Design

Following the PRISMA-ScR checklist, we searched scientific databases for eligible articles, their references, and explored related publications through a graphical tool (www.connectedpapers.com). Two independent reviewers performed article selection and characterization using a priori criteria.

Results

We describe data collected from 107 peer-reviewed articles that met our inclusion criteria. The literature reflects that tick species distributions have been modeled predominantly in North America and Europe and have mostly modeled the habitat suitability for Ixodes ricinus (n = 23; 21.5%). A wide range of bioclimatic databases and other environmental correlates were utilized among models, but the WorldClim database and its bioclimatic variables 1–19 appeared in 60 (56%) papers. The most frequently chosen modeling approach was MaxEnt, which also appeared in 60 (56%) of papers. Despite the importance of ensemble modeling to reduce bias, only 23 papers (21.5%) employed more than one algorithm, and just six (5.6%) used an ensemble approach that incorporated at least five different modeling methods for comparison. Area under the curve/receiver operating characteristic was the most frequently reported model validation method, utilized in nearly all (98.9%) included studies. Only 21% of papers used future climate scenarios to predict tick range expansion or contraction. Regardless of the representative concentration pathway, six of seven genera were expected to both expand and retract depending on location, while Ornithodoros was predicted to only expand beyond its current range.

Conclusion

Species distribution modeling techniques are useful and widely employed tools for predicting tick habitat suitability and range movement. However, the vast array of methods, data sources, and validation strategies within the SDM literature support the need for standardized protocols for species distribution and ecological niche modeling for tick vectors.

Molecular survey of cattle ticks in Burundi: First report on the presence of the invasive Rhipicephalus microplus tick

A recent research study on prevalence of tick-borne pathogens in Burundi reported high prevalence and endemicity of Theileria parva, Anaplasma marginale and Babesia bigemina infections in cattle. Detailed information about tick species infesting animals, their distribution and genetic diversity in Burundi is outdated and limited. This study therefore assessed the prevalence and genetic diversity of tick species infesting cattle across agroecological zones (AEZs) in Burundi. A cross-sectional study on the occurrence of tick species was conducted in 24 districts of Burundi between October and December 2017. Differential identification and characterization of ticks collected was conducted using tick morphological keys and molecular tools (cox1 and 12S rRNA gene). Chi-square test was used to test for association between agroecological zones and the prevalence of tick species. Phylogenetic relationships were inferred using bayesian and maximum likelihood algorithms. A total of 483 ticks were collected from the five AEZs sampled. Six tick species comprising of Rhipicephalus appendiculatus, R. sanguineus, R. evertsi evertsi, R. microplus, R. decoloratus and Amblyomma variegatum were observed. Rhipicephalus appendiculatus were the most prevalent ticks (~45%). A total of 138 specimens (28%) were found to be Rhipicephalus microplus, suggesting an emerging threat for cattle farmers. Twelve R. appendiculatus cox1 haplotypes were obtained from 106 specimens that were sequenced. Two cox1 haplotypes of R. microplus which clustered into previously reported Clade A were observed. Rhipicephalus sanguineus and R. evertsi evertsi ticks, the vectors of numerous zoonotic pathogens, were collected from cattle, which constitute a high risk for public health. These findings reveal an overlapping distribution of tick vectors in Burundi. The design of ticks and tick-borne diseases control strategies should consider the distribution of different vectors across the AEZs particularly the presence of the highly invasive R. microplus tick in Burundi and the potential risk of introducing the pathogenic Babesia bovis.

Protective efficacy of the peptide Subolesin antigen against the cattle tick Rhipicephalus microplus under natural infestation

The cattle tick Rhipicephalus microplus affect animal health, welfare, and cattle production in tropical and subtropical zones of the world. Anti-tick vaccines have been an effective alternative for cattle tick control instead of traditional chemical products. To date, Subolesin antigen has shown efficacy for the control of tick infestation in cattle, and previous studies showed that one peptide derived from this protein has demonstrated to elicit a strong and specific humoral immune response. Based on these findings, herein we characterized the efficacy of the peptide Subolesin for the control of cattle tick, R. microplus infestation under field conditions. Twenty-four female calves were assigned to four experimental groups and immunized with three subcutaneous doses of the peptide Subolesin, Bm86, both antigens (dual vaccine) and adjuvant/saline alone, respectively. Serum antibody levels (IgG) were assessed by ELISA and confirmed by Western blot; also, reproductive performance of naturally infested R. microplus was determined. The results showed that immunizations with the experimental antigens reduced tick infestations with vaccine's efficacy of 67 % (peptide Subolesin), 56 % (Bm86), and 49 % (dual vaccine) based on adult tick numbers, oviposition, and egg fertility between vaccinated and control animals. Peptide Subolesin-immunized calves developed a strong humoral immune response expressed by high anti-pSubolesin IgG levels, and the Western blot analysis confirmed that it is immunogenic. Cattle receiving Bm86 and dual vaccine showed less protection, although Bm86 was within the range reported previously. The negative correlation between antibody levels and reduction of naturally infested R. microplus strongly suggested that the effect of the vaccine was the result of the antibody response in immunized cattle. In conclusion, it was demonstrated that the peptide Subolesin induced a specific immune response in cattle under field conditions, resulting in reduced R. microplus populations in subsequent generations. Finally, integrated tick control must consider anti-tick vaccines as a cost-effective, sustainable, and successful tool for controlling cattle tick infestations.

Possible Effects of Climate Change on Ixodid Ticks and the Pathogens They Transmit: Predictions and Observations

The global climate has been changing over the last century due to greenhouse gas emissions and will continue to change over this century, accelerating without effective global efforts to reduce emissions. Ticks and tick-borne diseases (TTBDs) are inherently climate-sensitive due to the sensitivity of tick lifecycles to climate. Key direct climate and weather sensitivities include survival of individual ticks, and the duration of development and host-seeking activity of ticks. These sensitivities mean that in some regions a warming climate may increase tick survival, shorten life-cycles and lengthen the duration of tick activity seasons. Indirect effects of climate change on host communities may, with changes in tick abundance, facilitate enhanced transmission of tick-borne pathogens. High temperatures, and extreme weather events (heat, cold, and flooding) are anticipated with climate change, and these may reduce tick survival and pathogen transmission in some locations. Studies of the possible effects of climate change on TTBDs to date generally project poleward range expansion of geographical ranges (with possible contraction of ranges away from the increasingly hot tropics), upslope elevational range spread in mountainous regions, and increased abundance of ticks in many current endemic regions. However, relatively few studies, using long-term (multi-decade) observations, provide evidence of recent range changes of tick populations that could be attributed to recent climate change. Further integrated 'One Health' observational and modeling studies are needed to detect changes in TTBD occurrence, attribute them to climate change, and to develop predictive models of public- and animal-health needs to plan for TTBD emergence.

Rhipicephalus microplus seasonal dynamic in a Cerrado biome, Brazil: An update data considering the global warming

The present study evaluated over two years the seasonal dynamics of Rhipicephalus microplus in a Cerrado biome of midwestern Brazil (Goiânia, Goiás) and correlated the current climatic conditions (environmental temperature, insolation, rainfall, relative humitidy and saturation deficit of the atmosphere) of this site with 30 years ago. In addition, the data collected in the present research were compared with climatic conditions data and R. microplus population dynamics conducted by our group in other regions (Formiga, Minas Gerais and Jaboticabal, São Paulo) within the same biome. For the parasitic phase dynamics, R. microplus females (4.5-8.0 mm) counts were performed on tick natural infested cows kept in Panicum maximum paddocks. To verify the larvae dynamics on pasture the flannel dragg technique on natural infested pasture was performed, and the height of the grass was measured. Five peaks of engorged R. microplus females on animals and larvae infestations on pastures were observed. Being three and two peaks during the rainy and dry season of the year, respectively. Insolation (r = 0.8758; P = 0.00009; R² = 0.7670), rainfall (r = -0.8572; P = 0.0002; R² = 0.7348), maximum environmental temperature in summer (r = 0.9999; P < 0.0087; R² = 0.9988) and the saturation deficit of the atmosphere in autumn (r = -0.9789; P = 0.0211; R² = 0.9582) influenced the seasonal dynamics of R. microplus larvae on pastures. While the forage height did not influence the number of larvae found on pasture (r = 0.1545; P = 0.7682; R² = 0.0239). The comparison between the climatic data of the last 30 years with the current climatological data (2012 to 2019) in the state of Goiás, and the comparison with R. microplus population dynamics from other two locations in the same biome indicated that the increase of the environmental temperature due to the global warming possibly is a determining factor which increase the number of one or up two tick annual peaks. In addition, this climatic variable was responsible for increase the population density of ticks on pastures and animals observed in July/winter of the present study, in comparison to other regions with the same biome, as discussed in this work.

Predicting Hotspots and Prioritizing Protected Areas for Endangered Primate Species in Indonesia under Changing Climate

Simple Summary

Primates play an essential role in human life and its ecosystem. However, Indonesian primates have suffered many threats due to climate change and altered landscapes that lead to extinction. Therefore, primate conservation planning and strategies are important in maintaining their population. We quantified how extensively the protected areas overlapped primate hotspots and how it changes under mitigation and worst-case scenarios of climate change. Finally, we provide protected areas recommendations based on species richness and land-use changes under the worst-case scenario for Indonesian primate conservation planning and management options.

Abstract

Indonesia has a large number of primate diversity where a majority of the species are threatened. In addition, climate change is conservation issues that biodiversity may likely face in the future, particularly among primates. Thus, species-distribution modeling was useful for conservation planning. Herein, we present protected areas (PA) recommendations with high nature-conservation importance based on species-richness changes. We performed maximum entropy (Maxent) to retrieve species distribution of 51 primate species across Indonesia. We calculated species-richness change and range shifts to determine the priority of PA for primates under mitigation and worst-case scenarios by 2050. The results suggest that the models have an excellent performance based on seven different metrics. Current primate distributions occupied 65% of terrestrial landscape. However, our results indicate that 30 species of primates in Indonesia are likely to be extinct by 2050. Future primate species richness would be also expected to decline with the alpha diversity ranging from one to four species per 1 km². Based on our results, we recommend 54 and 27 PA in Indonesia to be considered as the habitat-restoration priority and refugia, respectively. We conclude that species-distribution modeling approach along with the categorical species richness is effectively applicable for assessing primate biodiversity patterns.