Ticks (Acari: Ixodidae) and rickettsiae associated with wild boars in a rural area of Minas Gerais, Brazil.

Wild boars or feral pigs are classified by the Brazilian Institute for the Environment and Renewable Resources (IBAMA) in "Category I of invasive exotic species". They cause economic losses, harm the environment, serve as hosts and reservoirs for several zoonotic disease agents, and provide a blood meal for tick species that act as vectors for zoonotic diseases. The objective of this study was to identify tick species on wild boars, assess host-seeking ticks in the related environment, and identify other potential tick hosts coexisting with wild boars on a farm located in the state of Minas Gerais, southeastern Brazil. Additionally, the study aimed to determine the presence of rickettsiae in these arthropods and assess the exposure of wild boars to rickettsiae species from the Spotted Fever Group and Rickettsia bellii through serology. A total of 3585 host-seeking ticks from three species (Amblyomma sculptum - 41.58%; Amblyomma dubitatum - 0.39% and Rhipicephalus microplus - 0.05%) were collected in the environment and A. sculptum was the most abundant species. Thirty-one wild boars were evaluated, resulting in the collection of 415 ticks, all of which were A. sculptum. Rickettsia DNA was not detected in samples of A. sculptum and R. microplus from the environment or in A. sculptum ticks from wild boars. However, all A. dubitatum ticks (n = 14) had Rickettsia bellii DNA confirmed by the species-specific PCR protocol. Out of the 31 serum samples from wild boars, 24 reacted with at least one Rickettsia antigen. Among these, seven individuals exhibited a reaction to a probable homologous antigen (PHA) of three rickettsiae species: R. rickettsii (n = 3), R. amblyommatis (n = 3) and R. rhipicephali (n = 1). Despite the high prevalence of seroreactivity, titers were low, indicating limited exposure to Rickettsia spp. Camera traps generated 874 animal records, capturing a total of 1688 individuals. At least 11 species of birds and 14 species of mammals (12 wild and two domestic) shared the environment with wild boars and potentially shared ticks with them. These findings provide baseline information for understanding the sharing of ticks and tick-borne pathogens between wild boars and other animals within the Cerrado biome. Further studies are necessary to monitor the potential and actual risk of wild boars to harbor infected ticks and their role in the transmission and maintenance cycle of Rickettsia spp.

MORPHOLOGICAL AND MOLECULAR CHARACTERIZATION OF AMBLYOMMA SCUTATUM (ACARI: IXODIDAE) ACCIDENTALLY INTRODUCED IN ITALY.

Eight ticks were found in Comacchio (FE), Italy parasitizing a young black iguana (Ctenosaura similis) that had been accidentally transported in a commercial plant container from Costa Rica. Specimens were identified morphologically as Amblyomma scutatum and then confirmed by the barcoding of the mitochondrial cytochrome c oxidase subunit 1 gene. Amblyomma scutatum is a common tick known to infest reptiles in Central America, Mexico, and Venezuela, but not in Europe. In Italy, the possibility for this tick to become endemic is unlikely because of the absence of its principal hosts. Nevertheless, this finding confirms the high risk of introducing exotic species that is linked with global commerce and therefore the need for veterinary control of shipments.

Parasitism on domestic cats by Amblyomma auricularium and serological evidence of exposure to Rickettsia amblyommatis.

The domestic cat is not considered a primary host for any specific tick species; however, it can be affected by some Ixodidae species, such as Rhipicephalus sanguineus sensu lato and Amblyomma spp. The study reports parasitism by Amblyomma auricularium and the detection of anti-Rickettsia spp. antibodies in domestic cats from a rural property in the Afrânio municipality, Pernambuco, Brazil. Amblyomma auricularium (24 nymphs, six females, and four males) and Amblyomma sp. (42 larvae) parasitized three cats, and 73 free-living ticks were captured in armadillo burrows: A. auricularium (36 nymphs, six females, five males) and Amblyomma sp. (26 larvae). Blood samples from cats were collected and the obtained plasma were subjected to indirect immunofluorescence assay (IFA) to detect antibodies against Rickettsia antigens. Thus, anti-Rickettsia spp. antibodies were determined (titers ranging from 128 to 512) and showed a predominant antibody response to Rickettsia amblyommatis or a very closely related genotype. This study reports the first infestation of nymphs and adults of A. auricularium on cats in a new area of occurrence in the semi-arid region of Northeastern Brazil and reports for the first time the presence of anti-Ricketsia antibodies in cats in the region, with R. amblyommatis as the probable infectious agent.

Density and behavior of capybara (Hydrochoerus hydrochaeris) ticks (Acari: Ixodidae) Amblyomma sculptum and Amblyomma dubitatum with notes on Rickettsia bellii infection: Assessing human exposure risk.

In several urban and peri­urban areas of Brazil, populations of Amblyomma sculptum and Amblyomma dubitatum ticks are maintained by capybaras (Hydrochoerus hydrochaeris). In some of these areas, this host and these tick species are associated with Brazilian spotted fever (BSF), a lethal human disease caused by the bacterium Rickettsia rickettsii. In this work, we evaluated the risk of human exposure to these tick species using four collection techniques to discern host-seeking behavior. The study was carried out in 10 urban sites inhabited by capybaras in Uberlândia, a BSF-free municipality in southeastern Brazil. Ticks were collected in areas of 400 m2 at each site and at three seasons. Within the same municipality, the distance and speed of A. sculptum nymphs moving towards the CO2 traps were evaluated. In a sample of ticks Rickettsia DNA was investigated. During the study period, 52,953 ticks were collected. Among these, 83.4 % were A. sculptum (1,523 adults, 10,545 nymphs and 32,104 larvae) and 16.6 % were A. dubitatum (464 adults, 2,153 nymphs and 6,164 larvae). An average annual questing tick density of 4.4/m² was observed, with the highest density recorded at one site in autumn (31.8/m²) and the lowest in summer at another site (0.03/m²). The visual search yielded the highest proportion of A. sculptum larvae, constituting 47 % of the total and 63.6 % of all A. sculptum larvae. In contrast, CO2 traps collected a greater proportion of nymphs and adults of A. sculptum ticks. In the case of A. dubitatum, the CO2 trap was the most efficient technique with 57.7 % of captures of this species, especially of nymphs (94.5 % of captures) and adults (97.8 % of captures). Ticks' ambush height on vegetation (9 to 77 cm), observed by visual search 30 times, yielded a total of 20,771 ticks. Of these, 28 (93 %) were A. sculptum ticks, with only two (7 %) identified as A. dubitatum ticks. Among A. sculptum ticks, the nymph was the most attracted stage to humans and larva in the case of A. dubitatum. Amblyomma sculptum adults and nymphs were significantly more attracted to humans than those of A. dubitatum, but A. dubitatum larvae were significantly more attracted than the same stage of A. sculptum. The maximum distance and speed of horizontal displacement for A. sculptum nymphs were five meters and 2.0 m/h, respectively. The only species of Rickettsia detected in ticks, exclusively in A. dubitatum, was R. bellii. Importantly, it was observed that the higher the proportion of A. sculptum in the community of ticks, the lower the rate of infection of A. dubitatum by R. bellii. In conclusion, host-seeking behavior differed between the two tick species, as well as between stages of the same species. A greater restriction of A. dubitatum ticks to the soil was observed, while larvae and nymphs of A. sculptum dispersed higher in the vegetation. The behavior presented by A. sculptum provides greater opportunities for contact with the hosts, while A. dubitatum depends more on an active search for a host, the hunter behavior. Taken together, these observations show that a human being crossing an area infested with A. sculptum and A. dubitatum ticks will have almost exclusive contact with A. sculptum larvae and/or nymphs. Humans in a stationary position (sitting, lying or immobile) are exposed to both tick species, but they are more attractive to adults and mainly nymphs of A. sculptum compared to the corresponding stages of the tick A. dubitatum. The negative effect of A. sculptum on A. dubitatum infection by R. bellii deserves further studies.

Molecular identification of Crimean-Congo haemorrhagic fever virus in Hyalomma rufipes and Amblyomma variegatum in the Upper East Region of Ghana.

Sampled ticks were screened for Crimean-Congo haemorrhagic fever virus (CCHFV) using an assay that targets the nucleoprotein gene region of the S segment, a conserved region of the CCHFV genome. Minimum infection rates of 0.34% and 0.10% were obtained when testing pools of Hyalomma rufipes and Amblyomma variegatum, respectively. Next-generation sequencing and phylogenetic analysis showed that the S and L segments of the CCHFV isolate clustered with those of similar isolates of genotype III. However, analysis of the M segment showed that reassortment had occurred, causing this segment to cluster with those of isolates of genotype I, providing the first evidence of such an occurrence in Ghana.

New hard tick (Acari: Ixodidae) reports and detection of Rickettsia in ticks from Sierra Nevada de Santa Marta, Colombia.

The Sierra Nevada de Santa Marta (SNSM), located in northern Colombia, is considered a geographical island with high levels of biodiversity and endemism. However, little is known about tick species and their associated microorganisms at the SNSM. In this study we sampled host-seeking ticks in areas of the town of Minca within the SNSM. We collected 47 ticks identified as Amblyomma pacae, Amblyomma longirostre, Amblyomma ovale, Amblyomma mixtum, Haemaphysalis juxtakochi, Ixodes sp. cf. Ixodes affinis and Ixodes sp. Of these ticks, we tested for Rickettsia spp. by amplifying the gltA, SCA1, and 16S rRNA genes via PCR. Rickettsia amblyommatis was detected in one pool of 3 larvae and in a female of A. pacae. Additonally, we isolated Rickettsia sp. belonging to the group of spotted fevers in larvae of A. longirostre. This study reports new findings of six species of ticks and two species of Rickettsia within the SNSM.

New insights into the molecular phylogeny, biogeographical history, and diversification of Amblyomma ticks (Acari: Ixodidae) based on mitogenomes and nuclear sequences.

BACKGROUND: Amblyomma is the third most diversified genus of Ixodidae that is distributed across the Indomalayan, Afrotropical, Australasian (IAA), Nearctic and Neotropical biogeographic ecoregions, reaching in the Neotropic its highest diversity. There have been hints in previously published phylogenetic trees from mitochondrial genome, nuclear rRNA, from combinations of both and morphology that the Australasian Amblyomma or the Australasian Amblyomma plus the Amblyomma species from the southern cone of South America, might be sister-group to the Amblyomma of the rest of the world. However, a stable phylogenetic framework of Amblyomma for a better understanding of the biogeographic patterns underpinning its diversification is lacking. METHODS: We used genomic techniques to sequence complete and nearly complete mitochondrial genomes -ca. 15 kbp- as well as the nuclear ribosomal cluster -ca. 8 kbp- for 17 Amblyomma ticks in order to study the phylogeny and biogeographic pattern of the genus Amblyomma, with particular emphasis on the Neotropical region. The new genomic information generated here together with genomic information available on 43 ticks (22 other Amblyomma species and 21 other hard ticks-as outgroup-) were used to perform probabilistic methods of phylogenetic and biogeographic inferences and time-tree estimation using biogeographic dates. RESULTS: In the present paper, we present the strongest evidence yet that Australasian Amblyomma may indeed be the sister-group to the Amblyomma of the rest of the world (species that occur mainly in the Neotropical and Afrotropical zoogeographic regions). Our results showed that all Amblyomma subgenera (Cernyomma, Anastosiella, Xiphiastor, Adenopleura, Aponomma and Dermiomma) are not monophyletic, except for Walkeriana and Amblyomma. Likewise, our best biogeographic scenario supports the origin of Amblyomma and its posterior diversification in the southern hemisphere at 47.8 and 36.8 Mya, respectively. This diversification could be associated with the end of the connection of Australasia and Neotropical ecoregions by the Antarctic land bridge. Also, the biogeographic analyses let us see the colonization patterns of some neotropical Amblyomma species to the Nearctic. CONCLUSIONS: We found strong evidence that the main theater of diversification of Amblyomma was the southern hemisphere, potentially driven by the Antarctic Bridge's intermittent connection in the late Eocene. In addition, the subgeneric classification of Amblyomma lacks evolutionary support. Future studies using denser taxonomic sampling may lead to new findings on the phylogenetic relationships and biogeographic history of Amblyomma genus.

Encapsulation of carvacrol and thymol with yeast cell wall and its repellent activity against Amblyomma sculptum and Rhipicephalus sanguineus (Sensu Lato).

The main way to avoid contact with ticks and consequently tick-borne disease is the use of synthetic repellents. The search of new repellent compounds to increase the possibilities of use in strategies controls are necessary. The present study evaluated the repellent activity of two natural terpenes carvacrol and thymol in each one two different formulation (encapsulated and nonencapsulated with yeast cell wall) against the ticks Amblyomma sculptum and Rhipicephalus sanguineus sensu lato nymphs. Nymphs of A. sculptum and R. sanguineus s.l. of a single generation were used. The vertical filter paper repellency assay were performed with different concentration of both terpenes encapsulated and nonencapsulated in yeast cell wall. The repellent concentration 50% (RC50) were calculated to each compound formulation. Both carvacrol and thymol (encapsulated and nonencapsulated), had a repellent activity against A. sculptum and R. sanguineus s.l nymphs. Amblyomma sculptum was more sensitive to nonencapsulated carvacrol (RC50 values: 0.0032 to 0.0082 mg/cm2 after 1 and 15 min) (P < 0.05), while R. sanguineus s.l. was more sensitive to encapsulated carvacrol (RC50 values: 0.00008 to 0.0035 mg/cm2 after 1 and 15 min) (P < 0.05). Among tick species, R. sanguineus s.l. was more sensitive for most compounds than A. sculptum (P < 0.05). Although with distinct repellent activities, carvacrol and thymol encapsulated can be a promising alternative to synthetic repellents against A. sculptum and R. sanguineus s.l.

The first cryptic genus of Ixodida, Cryptocroton n. gen. for Amblyomma papuanum Hirst, 1914: a tick of North Queensland, Australia, and Papua New Guinea.

We describe a new genus Cryptocroton n. gen. for Amblyomma papuanum Hirst, 1914, a tick of North Queensland, Australia, and Papua New Guinea.

Human risk to tick encounters in the southeastern United States estimated with spatial distribution modeling.

Expanding geographic distribution and increased populations of ticks has resulted in an upsurge of human-tick encounters in the United States (US), leading to an increase in tickborne disease reporting. Limited knowledge of the broadscale spatial range of tick species is heightened by a rapidly changing environment. Therefore, we partnered with the Forest Inventory and Analysis (FIA) program of the Forest Service, U.S. Department of Agriculture and used passive tick surveillance to better understand spatiotemporal variables associated with foresters encountering three tick species (Amblyomma americanum L., Dermacentor variabilis Say, and Ixodes scapularis L.) in the southeastern US. Eight years (2014-2021) of tick encounter data were used to fit environmental niche and generalized linear models to predict where and when ticks are likely to be encountered. Our results indicate temporal and environmental partitioning of the three species. Ixodes scapularis were more likely to be encountered in the autumn and winter seasons and associated with soil organic matter, vegetation indices, evapotranspiration, temperature, and gross primary productivity. By contrast, A. americanum and D. variabilis were more likely to be encountered in spring and summer seasons and associated with elevation, landcover, temperature, dead belowground biomass, vapor pressure, and precipitation. Regions in the southeast least suitable for encountering ticks included the Blue Ridge, Mississippi Alluvial Plain, and the Southern Florida Coastal Plain, whereas suitable regions included the Interior Plateau, Central Appalachians, Ozark Highlands, Boston Mountains, and the Ouachita Mountains. Spatial and temporal patterns of different tick species can inform outdoorsmen and the public on tick avoidance measures, reduce tick populations by managing suitable tick habitats, and monitoring areas with unsuitable tick habitat for potential missed encounters.

Exotic ticks removed from German travelers.

We report the finding of five nymphs and three adult ticks attached to German tourists while traveling the American continents. All eight specimens were morphologically identified and confirmed genetically using the 16S rRNA gene and screened for Rickettsia spp. infections. Five tick species were identified: one Amblyomma mixtum nymph from Ecuador, one Amblyomma varium nymph from Colombia, three Amblyomma coelebs nymphs from Costa Rica, one Amblyomma americanum male from the USA, one Dermacentor andersoni female and one D. andersoni male from Canada. Tick-borne microorganisms screening using the pan-Rickettsia-PCR resulted in two positive and six negative ticks. The A. mixtum nymph was positive for Rickettsia amblyommatis, while the D. andersoni female was positive for Rickettsia peacockii.

New insights into the systematics of the afrotropical Amblyomma marmoreum complex (Acari: Ixodidae) and the genome of a novel Rickettsia africae strain using morphological and metagenomic approaches.

The Amblyomma marmoreum complex includes afrotropical species, such as Amblyomma sparsum, a three-host tick that parasitizes reptiles, birds, and mammals, and is a recognized vector of Ehrlichia ruminantium. However, the lack of morphological, genetic and ecological data on A. sparsum has caused considerable confusion in its identification. In this study, we used microscopy and metagenomic approaches to analyze A. sparsum ticks collected from a puff adder snake (Bitis arietans) in southwest Senegal (an endemic rickettsioses area) in order to supplement previous morphological descriptions, provide novel genomic data for the A. marmoreum complex, and describe the genome of a novel spotted fever group Rickettsia strain. Based on stereoscope and scanning electron microscopy (SEM) morphological evaluations, we provide high-quality images and new insights about punctation and enameling in the adult male of A. sparsum to facilitate identification for future studies. The metagenomic approach allowed us assembly the complete mitochondrial genome of A. sparsum, as well as the nearly entire chromosome and complete plasmid sequences of a novel Rickettsia africae strain. Phylogenomic analyses demonstrated a close relationship between A. sparsum and Amblyomma nuttalli for the first time and confirmed the position of A. sparsum within the A. marmoreum complex. Our results provide new insights into the systematics of A. sparsum and A. marmoreum complex, as well as the genetic diversity of R. africae in the Afrotropical region. Future studies should consider the possibility that A. sparsum may be a vector for R. africae.

Virome analyses of Amblyomma cajennense and Rhipicephalus microplus ticks collected in Colombia.

Tick-borne viruses (TBV) have gained public health relevance in recent years due to the recognition of human-associated fatal cases and the increase in tick-borne disease and transmission. However, many tick species have not been studied for their potential to transmit pathogenic viruses, especially those found in Latin America. To gain better understanding of the tick virome, we conducted targeted amplification using broadly-reactive consensus-degenerate pan-viral targeting viruses from the genera Flavivirus, Bandavirus, Uukuvirus, and Orthonairovirus genus. Additionally, we conducted unbiased metagenomic analyses to investigate the presence of viral RNA sequences in Amblyomma cajennense, A. patinoi and Rhipicephalus microplus ticks collected from a horse slaughter plant in Medellín, Colombia. While no viral products were detected by PCR, results of the metagenomic analyses revealed the presence of viral genomes belonging to the genera Phlebovirus, Bandavirus, and Uukuvirus, including Lihan Tick Virus (LTV), which was previously reported in Rhipicephalus microplus from Colombia. Overall, the results emphasized the enormous utility of the next-generation sequencing in identifying virus genetic diversity presents in ticks and other species of vectors and reservoirs.

Mapping the distribution of Amblyomma americanum in Georgia, USA.

BACKGROUND: Amblyomma americanum, the lone star tick, is an aggressive questing species that harbors several pathogens dangerous to humans in the United States. The Southeast in particular has large numbers of this tick due to the combined suitable climate and habitats throughout the region. No studies have estimated the underlying distribution of the lone star tick across the state of Georgia, a state where it is the dominant species encountered. METHODS: Ticks were collected by flagging 198 transects of 750 m2 at 43 state parks and wildlife management areas across the state from March to July of 2022. A suite of climate, landscape, and wildlife variables were assembled, and a logistic regression model was used to assess the association between these environmental factors and the presence of lone star ticks and to predict the distribution of these ticks across the state. RESULTS: A total of 59/198 (30%) transects sampled contained adult or nymph A. americanum, with the majority of transects containing these ticks (54/59, 91.5%) in forested habitats. The presence of A. americanum was associated with elevation, normalized difference vegetation index (NDVI) on January 1, isothermality, temperature seasonality, and precipitation in the wettest quarter. Vast regions of central, eastern, and southern coastal Georgia (57% of the state) were categorized as suitable habitat for the lone star tick. CONCLUSIONS: This study describes the distribution of the lone star tick across the state of Georgia at a finer scale than the current county-level information available. It identifies specific variables associated with tick presence and provides a map that can be used to target areas for tick prevention messaging and awareness.

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.

Survey of Rickettsia spp. in ticks (Acari: Ixodidae) infesting opossums (Didelphis albiventris) and capybaras (Hydrochoerus hydrochaeris) from an urban park in southeastern Brazil.

Ticks are hematophagous arthropods and, during feeding, may transmit pathogens to vertebrate hosts, including humans. This study aimed to investigate the presence of Rickettsia spp. in ticks collected between 2010 and 2013 from free-ranging capybaras (Hydrochoerus hydrochaeris) and opossums (Didelphis albiventris) that inhabit Sabiá Park in Uberlândia, Brazil. Overall, 1,860 ticks were collected: 1,272 (68.4%) from capybaras (487 of the species Amblyomma sculptum, 475 adults and 12 nymphs; 778 Amblyomma dubitatum, 727 adults and 51 nymphs; and seven larva clusters of the genus Amblyomma); and 588 (31.6%) from opossums (21 A. sculptum, one adult and 20 nymphs; 79 A. dubitatum, all nymphs; 15 Ixodes loricatus, 12 adults and three nymphs; 457 Amblyomma sp. larva clusters; 15 Ixodes sp. larva clusters; and one Argasidae larva cluster). Out of 201 DNA samples tested for the presence of Rickettsia spp. DNA using polymerase chain reaction (PCR) 12 showed amplification of a gtlA gene segment that was specific to Rickettsia bellii, a bacterium non-pathogenic to humans. As there has been a report showing serological evidence of infections caused by Rickettsia species of the spotted fever group (SFG) in capybaras and opossums in the park, including Rickettsia rickettsii, the etiological agent of Brazilian spotted fever, and considering the presence of A. sculptum ticks, which are aggressive to humans, as well as these vertebrate hosts, which are amplifiers of R. rickettsii, it is important to monitor the presence of SFG rickettsiae in the Sabiá Park, which is visited daily by thousands of people.

Repellent activity of the non-host semiochemical (E)-2-octenal against Amblyomma sculptum and Amblyomma dubitatum ticks under field conditions.

Amblyomma ticks pose a significant public health threat due to their potential to transmit pathogens associated with rickettsial diseases. (E)-2-octenal, a compound found in donkeys (Equus asinus), exhibits strong repellent properties against Amblyomma sculptum nymphs under laboratory conditions. This study assessed the effectiveness of the (E)-2-octenal in wearable slow-release devices for personal human protection against Amblyomma ticks under natural conditions. Slow-release devices treated with (E)-2-octenal and untreated controls were prepared and tested on two volunteers walking through a tick-infested area in Goiania, Brazil. The experiment was conducted twice daily for three series of 10 days, with each volunteer wearing two devices attached to each leg, one on the ankle and one just above the thigh. Volunteers with control and treated devices exchanged them between rounds. Also, the daily release rate of (E)-2-octenal from the slow-release devices was determined in the laboratory, increasing significantly from 0.77 ± 0.14 µg/day on the first day to 9.93 ± 1.92 µg/day on the 4th day and remaining constant until the 16th day. A total of 5409 ticks were collected from both volunteers. Treated devices resulted in recovering fewer ticks (n = 1,666; 31%) compared to untreated devices (control: n = 3,743; 69%). (E)-2-octenal effectively repelled Amblyomma spp. larvae, A. sculptum adults, and exhibited pronounced repellency against A. dubitatum nymphs and adults. These findings suggest the potential of (E)-2-octenal delivered by wearable slow-release devices as a green-based repellent. Further improvements, however, are necessary to provide better protection for humans against A. sculptum and A. dubitatum in field conditions.

Distribution and prevalence of ixodid tick species (Acari: Ixodidae) infesting cattle in Karamoja region of northeastern Uganda.

BACKGROUND: Ticks and tick-borne diseases (TTBDs) are a significant threat to livestock production in sub-Saharan Africa. Transhumance pastoralism practiced in Karamoja region and other factors like cattle trade, communal grazing and the presence of wildlife predispose cattle to TTBDs. Tick species abundance and distribution data can be used as a tool for early disease diagnosis and inform tick control strategies. However, these data for north-eastern Uganda are currently limited; previous surveys were relatively localized and targeted fewer cattle kraals and numbers. METHODS: We randomly collected tick specimens from 1,534 cattle spread across Karamoja region in both the peak month of the rainy (May 2020) and the dry (February2021) seasons. The ticks were identified using morpho-taxonomic keys and the tick species identities confirmed by the 16 S rRNA gene sequencing and phylogenetic analysis. RESULTS: A collection of 18,637 ticks was examined and fifteen tick species from three genera (ten Rhipicephalus; three Amblyomma; two Hyalomma species) were identified. Rhipicephalus appendiculatus was the most dominant (37.9%) tick species, followed by Amblyomma variegatum (32.3%); A. lepidum (17.3%); R. evertsi evertsi (7.8%); and R. decoloratus (1.4%). Eight of these tick species were ubiquitous in the study districts while six were found in isolated areas. The peak month of the dry season collection was associated with a higher proportion of tick-infested cattle (91%) compared to the peak month of the rainy season (89.8%); a difference that was not found statistically significant (χ2 = 0.5077, n = 1385, p = 0.476). The overall cattle infestation rate was mainly dominated by five tick species namely: A. variegatum (55%), R. appendiculatus (53%), A. lepidum (41%), R. evertsi (22%), and R. decoloratus (8%). The proportion of tick-infested cattle was highest in Napak District (95.4%) and lowest in Amudat District (80.9%) during the peak month of the rainy season. Napak and Amudat Districts also had the highest and lowest proportion of tick-infested cattle (94.8% and 80.7% respectively) during the peak month of the dry season. Rhipicephalus microplus was confirmed in Amudat, Kaabong and Napak districts. CONCLUSION: This study demonstrates high tick infestation rates in cattle by a battery of tick species in Karamoja region. We identified both R. microplus and R. decoloratus which indicates that R. microplus has recently been introduced in this region. This calls for effective tick control responses to prevent further spread of this invasive cattle tick specie.

First report of Anaplasma spp., Ehrlichia spp., and Rickettsia spp. in Amblyomma gervaisi ticks infesting monitor lizards (Varanus begalensis) of Pakistan.

Ticks pose significant health risks to both wildlife and humans due to their role as vectors for various pathogens. In this study, we investigated tick infestation patterns, tick-associated pathogens, and genetic relationships within the tick species Amblyomma gervaisi, focusing on its prevalence in monitor lizards (Varanus bengalensis) across different districts in Pakistan. We examined 85 monitor lizards and identified an overall mean intensity of 19.59 ticks per infested lizard and an overall mean abundance of 11.98 ticks per examined lizard. All collected ticks (n = 1019) were morphologically identified as A. gervaisi, including 387 males, 258 females, 353 nymphs, and 21 larvae. The highest tick prevalence was observed in the Buner district, followed by Torghar and Shangla, with the lowest prevalence in Chitral. Lizard captures primarily occurred from May to October, correlating with the period of higher tick infestations. Molecular analysis was conducted on tick DNA, revealing genetic similarities among A. gervaisi ticks based on 16S rDNA and ITS2 sequences. Notably, we found the absence of A. gervaisi ITS2 sequences in the NCBI GenBank, highlighting a gap in existing genetic data. Moreover, our study identified the presence of pathogenic microorganisms, including Ehrlichia sp., Candidatus Ehrlichia dumleri, Anaplasma sp., Francisella sp., Rickettsia sp., and Coxiella sp., in these ticks. BLAST analysis revealed significant similarities between these pathogenic sequences and known strains, emphasizing the potential role of these ticks as vectors for zoonotic diseases. Phylogenetic analyses based on nuclear ITS2 and mitochondrial 16S rDNA genes illustrated the genetic relationships of A. gervaisi ticks from Pakistan with other Amblyomma species, providing insights into their evolutionary history. These findings contribute to our understanding of tick infestation patterns, and tick-borne pathogens in monitor lizards, which has implications for wildlife health, zoonotic disease transmission, and future conservation efforts. Further research in this area is crucial for a comprehensive assessment of the risks associated with tick-borne diseases in both wildlife and humans.

Ultrastructural characterization and quantification of hemocytes in engorged female Amblyomma sculptum ticks.

Amblyomma sculptum (formerly Amblyomma cajennense) ticks have been implicated in the transmission of pathogens that cause diseases in animals and humans. Their wide geographic distribution and high impact on animal health and zoonotic disease transmission highlight the importance of studying and implementing effective control measures to mitigate the risks associated with this tick species. The aim of this study was to quantify and characterize the morphology and the ultrastructure of different types of hemocytes in the hemolymph in engorged A. sculptum females fed on rabbits. The hemolymph samples were collected by perforation of the cuticle in the dorsal region. Hemocyte types, sizes, and differential counts were determined using light microscopy, while ultrastructural analysis of hemocytes was performed using transmission electron microscopy. The average number of total hemocytes in the hemolymph was 1024 ± 597.6 cells µL-1. Five morphologically distinct cell types were identified in A. sculptum females: prohemocytes (6 % ± 8.8), plasmatocytes (10 % ± 7.7), granulocytes (78 % ± 12.2), spherulocytes (5 % ± 4.48), and oenocytoids (1 % ± 1.6). In general, prohemocytes were the smallest hemocytes. The ultrastructural morphology of A. sculptum hemocytes described in the present study agrees with the findings for other hard ticks. This is the first study to investigate ultrastructural characteristics of hemocytes of female A. sculptum ticks.