Hyalomma scupense (Acari, Ixodidae) in northeast Tunisia: seasonal population dynamics of nymphs and adults on field cattle

A Review on Crimean-Congo Hemorrhagic Fever Infections in Tunisia

Crimean-Congo hemorrhagic fever (CCHF) is a zoonotic tick-borne disease, caused by an arbovirus of the genus Orthonairovirus and the family Nairoviridae. Crimean-Congo hemorrhagic fever virus (CCHFV) is widespread in several regions of the world. While the virus is not pathogenic to all susceptible livestock and wild mammals, it can lead to severe hemorrhagic fever in humans. In this review, we compiled published data on CCHFV infections in humans, animals, and ticks in Tunisia. Based on that, we discussed the epidemiology and the distribution patterns of CCHFV infections highlighting the risk factors for this virus in the country. CCHF infection prevalence in humans was estimated to 2.76% (5/181) and 5% (2/38) in Tunisian febrile patients and Tunisian slaughterhouse workers, respectively. Concurrently, seroprevalence in domestic ungulates (sheep, goats, cattle, and dromedaries) ranged from zero to 89.7%, and only one Hyalomma impeltatum tick specimen collected from dromedaries in southern Tunisian was positive for CCHFV by reverse transcriptase-polymerase chain reaction (0.6%; 1/165). As Tunisian studies on CCHFV are geographically scattered and limited due to very small sample sizes, further studies are needed to improve the knowledge on the epidemiology of CCHF in Tunisia.

Molecular detection and characterization of Theileria annulata, Babesia bovis, and Babesia bigemina infecting cattle and buffalo in southern Egypt

Tick-borne diseases have a major adverse effect on livestock worldwide, causing enormous economic losses in meat and milk production as well threatening animal and public health. In this study, we aimed to detect and characterize piroplasms isolated from cattle and buffalo in southern Egypt, using molecular techniques. Three hundred blood samples were collected from cattle and buffalo in two governorates in southern Egypt. All 300 samples (100%) were confirmed to contain DNA, as they exhibited bands of bovine β-actin gene at the expected 227 bp for cattle and buffalo. The samples were analyzed by PCR for the presence of piroplasms, specifically Babesia bovis, Babesia bigemina, and Theileria annulata. Samples positive for the piroplasma 18S ribosomal RNA gene were further examined for two additional genes, spherical body protein 4 gene, to provide an enhanced degree of specificity for the identification of B. bovis and B. bigemina, and the major merozoite surface antigen gene for T. annulata. The infection rate for piroplasma spp. was 60/300 (20%). The positivity rates were 10.7% (32/300) for T. annulata, 5.3% (16/300) for B. bovis, and 4% (12/300) for B. bigemina. By host species, 42/150 (28%) cattle and 18/150 (12%) buffalo were positive for piroplasms. None of the isolates sequenced for the B. bovis isolates from buffalo in this study showed 100% identity with any sequence deposited in GenBank for the small subunit ribosomal RNA gene (maximum identity value = 99.74%). Similarly, no T. annulata small subunit ribosomal RNA gene sequence identified in this study exhibited 100% identity with any sequence deposited in GenBank (maximum identity value = 99.89%). The current study provides a partial sequence of the T. annulata merozoite-piroplasm surface antigen gene, as well as the B. bovis and B. bigemina spherical body protein 4 genes, in cattle and buffalo in southern Egypt, and is the first report on these piroplasma genes in cattle and buffalo in southern Egypt.

In vitro feeding of all life stages of two-host Hyalomma excavatum and Hyalomma scupense and three-host Hyalomma dromedarii ticks

Ticks are blood-sucking ectoparasites and can transmit various pathogens of medical and veterinary relevance. The life cycle of ticks can be completed under laboratory conditions on experimental animals, but the artificial feeding of ticks has attracted increased interest as an alternative method. This study represents the first report on the successful in vitro feeding of all life stages of two-host tick species, Hyalomma scupense and Hyalomma excavatum, and the three-host tick Hyalomma dromedarii. The attachment and engorgement rates of adults were 84% (21/25) and 76% (19/25) for H. scupense females. For adult H. excavatum and H. dromedarii, 70% (21/30) and 34.4% (11/32) of the females attached and all attached females successfully fed to repletion. The oviposition rates of the artificially fed females were 36.4%, 57.1% and 63.1% for H. dromedarii, H. excavatum and H. scupense, respectively, with a reproductive efficiency index varying between 44.3 and 60.7%. For the larvae, the attachment and engorgement rates were 44.2% (313/708) and 42.8% (303/708) for H. dromedarii, 70.5% (129/183) and 56.8% (104/183) for H. excavatum and 92.6% (113/122) and 55.7% (68/122) for H. scupense. The attachment and engorgement rates for the nymphs were 90.2% (129/143) and 47.6% (68/143) for H. dromedarii, 66.7% (34/51) and 41.2% (21/51) for H. excavatum, and 44.1% (30/68) and 36.8% (25/68) for H. scupense. Molting rates of the immature stages varied between 71.3% (216/303) and 100% (68/68) for the larvae and between 61.9% (13/21) and 96% (24/25) for the nymphs. The successful in vitro feeding of all stages of the three Hyalomma species makes this method a valuable tool for tick research, with potential applications in studies on the pathogens transmitted by these tick species such as Theileria annulata.

Epidemiological situation of bovine tropical theileriosis in an arid region in central Tunisia with a phylogenetic analysis of Theileria annulata

BACKGROUND

Tropical theileriosis, Theileria annulata infection, is the most prevalent summer disease in Tunisia. It is transmitted by Hyalomma scupense, a two-host tick known to be endophilic.

OBJECTIVES

The present study aimed to estimate the infection prevalence of cattle by T. annulata in two districts from central Tunisia.

METHODS

Blood samples collected from 270 Holstein cattle from the Sidi Bouzid (140 samples) and Kasserine districts (130 samples) were analysed by Giemsa staining and T. annulata-specific PCR.

RESULTS

In both regions, PCR revealed a prevalence of 32.6%. This was significantly higher than the 6.3% prevalence obtained by Giemsa staining blood smears (p < 0.001). Giemsa staining also revealed a low parasitaemia of 0.05%. The PCR-based prevalence was not statistically different between the two districts (31.4 ± 0.04 and 33.8 ± 0.04% in Sidi Bouzid and Kasserine districts, respectively, p = 0.6). On the contrary, the results of blood smear examination (2.85 and 10% in Sidi Bouzid and Kasserine, respectively) differed significantly between the two sampling sites (p = 0.01). There was no evidence of a statistically significant difference between the overall molecular infection prevalence when the samples were segregated based on animals' age or gender (p = 0.1 and 0.2, respectively) and a similar trend was observed for Giemsa staining. Ten PCR amplicons of the Tams1 gene (721 bp) were subsequently sequenced from the two regions. The phylogenetic analyses showed 100% similarity between all sequences. The unique conserved Tams1 sequence was deposited in GenBank under the accession number OP428816 and used to infer its phylogenetic relationships with those available in the GenBank repository.

CONCLUSIONS

This is the first report of the presence of T. annulata in this region of central Tunisia which has no history of tropical theileriosis. Priority areas for future studies include understanding the origin of these T. annulata-positive animals in a region where the presence of a known natural vector tick, H. scupense, has not been reported. Given that the disease severely constrains cattle productivity, it would also be worthwhile to investigate if other potential vectors for T. annulata, such as Hyalomma dromedarii, are present in the arid regions.

Toxicity, repellency, and anti-cholinesterase activities of bioactive molecules from clove buds Syzygium aromaticum L. as an ecological alternative in the search for control Hyalomma scupense (Acari: Ixodidae)

Introduction

The goal of the current study is to evaluate the acaricidal and repellent properties of the ethanolic extract, essential oil, and primary component eugenol from Syzygium aromaticum against Hyalomma scupense cattle ticks. Their potential mechanisms of action were also examined, using an in vitro assay.

Methods

Clove essential oil was extracted using hydrodistillation technique. Gas chromatography-mass spectrometry (GC-MS) was performed to identify the chemical composition of clove. To evaluate the adulticidal, ovicidal, larvicidal and repellent proprieties of clove essential oil, eugenol and ethanolic extract on H. scupense, in vitro assays were performed using the adult immersion test (AIT), the ovicidal test, the larval packet test (LPT), the filter paper test and anti-acetylcholinesterase (AChE) activity.

Results

After treatment, eugenol, the primary phytoconstituent of clove oil, which accounts for 97.66% of the whole oil, had 99.22% acaricide activity and inhibited egg hatching at a concentration of 10 mg/mL. Eugenol and clove essential oil showed potent adulticidal effect at high concentrations (10 mg/mL), achieving 100 and 93.76% mortality, respectively. The ethanolic extract exhibited moderate activity. At high concentration, the larvicidal activity of S. aromaticum oil, eugenol, and ethanolic extract were 100, 100, and 77.18%, respectively. In filter paper experiments, when tested at the concentration 5 mg/mL; eugenol showed the longest repellent effect up to 6 h. We also found that eugenol was the most active AChE inhibitor (IC50 = 0.178 mg/mL). Nevertheless, additional investigations are required to confirm the accurate mechanism and the relevance of clove in practical application.

Conclusion

Overall, our research indicated that, because its effectiveness as acaricide, S. aromaticum essential oil and its phytoconstituent eugenol may offer an alternative source for the control of H. scupense cattle ticks.

An Update of Evidence for Pathogen Transmission by Ticks of the Genus Hyalomma

Current and likely future changes in the geographic distribution of ticks belonging to the genus Hyalomma are of concern, as these ticks are believed to be vectors of many pathogens responsible for human and animal diseases. However, we have observed that for many pathogens there are no vector competence experiments, and that the level of evidence provided by the scientific literature is often not sufficient to validate the transmission of a specific pathogen by a specific Hyalomma species. We therefore carried out a bibliographical study to collate the validation evidence for the transmission of parasitic, viral, or bacterial pathogens by Hyalomma spp. ticks. Our results show that there are very few validated cases of pathogen transmission by Hyalomma tick species.

The life cycle of Hyalomma scupense (Acari: Ixodidae) under laboratory conditions

The life cycle of Hyalomma scupense on rabbit hosts was investigated under laboratory conditions. Hy. scupense exhibited one- and two-host life cycles of 163.2 and 161.4 days, respectively. The incubation of eggs required an average period of 52 days, which was the longest period among the four developmental stages. The average time for pre-feeding of larvae was 3.5 days. It took 20 days for larvae to become engorged nymphs and 52.3 days to become engorged females. The duration of the pre-feeding, feeding, pre-oviposition, and oviposition stages of female adults was 2.3, 13.5, 27.5, and 27.9 days, respectively. The average weight of engorged females was 390.0 mg (ranging from 129.3 mg to 828.6 mg), which was 28.95 times the weight of unfed females. There was a positive relationship between the weight and the number of eggs laid by engorged females (r = 0.927). The reproductive efficiency index (REI) was 8.63.

Acaricidal and anthelmintic efficacy of Ocimum basilicum essential oil and its major constituents estragole and linalool, with insights on acetylcholinesterase inhibition

The present study evaluated the acaricidal and anthelmintic action of Ocimum basilicum essential oil and its main components against ticks and helminth parasites as well as to relate these activities to acetylcholinesterase inhibition. The in vitro acaricidal activity against Hyalomma scupense was evaluated by Adult Immersion Test (AIT) and Larval Packet Test (LPT), while the in vivo nematocidal potential was assessed in laboratory mice infected with Heligmosomoides polygyrus using fecal egg count reduction (FECR) and total worm count reduction (TWCR). Chemical analyzes were performed by gas chromatography coupled to mass spectrometry (GC-MS). Estragole (80.87%) and linalool (16.12%) were the major compounds detected in O. basilicum essential oil. In the AIT assay for H. scupense tick, LC₅₀ of estragole, O. basilicum oil and linalool were 0.73, 0.81 and 0.97 mg/mL, respectively. In LPT, estragole, linalool and essential oil showed LC₅₀ of 0.22, 1.11 and 1.19 mg/mL, respectively. Against He. polygyrus, the highest activity was observed with estragole administered at 100 mg/kg body weight (bwt), which resulted in a FECR of 90.86% and a TWCR of 82.91%. The O. basilicum essential oil, estragole and linalool inhibited the enzyme acetylcholinesterase (AChE) extracted from both parasites species. Estragole was found the most active AChE inhibitor with IC₅₀ of 0.176 mg/mL for H. scupense and IC₅₀ of 0.138 mg/mL for He. polygyrus larvae. The results of the present study pointed out the importance of the traditional use of O. basilicum as an eco-friendly alternative against endo and ectoparasites. In vivo trials should also be conducted to confirm the above-mentioned activities and to assure the safe use of natural plants.

In vitro acaricidal activity of essential oil and crude extracts of Laurus nobilis, (Lauraceae) grown in Tunisia, against arthropod ectoparasites of livestock and poultry: Hyalomma scupense and Dermanyssus gallinae

The current study assayed the toxicity of Laurus nobilis essential oil and crude extracts obtained using solvents of increasing polarity (cyclohexane, acetone and ethanol), on two ectoparasites of veterinary importance, i.e., Hyalomma scupense and Dermanyssus gallinae. The major components detected in bay laurel essential oil were dominated by 1.8-cineole (46.56 %), α-terpinenyl acetate (13.99 %), sabinene (7.69), α-pinene (5.75), linalool (5.50), methyleugenol (5.36 %) and β-pinene (3.97). The highest total phenolic and flavonoids contents were present in the ethalonic extract of L. nobilis leaves at an amount of 152.88 mg gallic acid equivalents per gram of dry weight (GAE/g DW) and 21.77 mg quercetin equivalent per gram of dry weight (QE/g DW), respectively. In vitro acaricidal effects of essensial oil and crude extract of L. nobilis against H. scupense were ascertained by adult immersion test of engorged females (AIT) and larval packet test (LPT) compared with a reference drug amitraz. The essential oil exhibited strong acaricidal activity against tick engorged female and inhibition of hatching eggs. After 24 h of exposure, at the highest tested concentration (100 mg/mL) essential oil induced 90.67 % mortality of H. scupense larvae (LC₅₀ = 10.69 mg/mL). Otherwise, essential oil exhibited high acaricidal activity compared to extracts, and among the extract, the ethanolic extract revealed the highest acaricidal efficacy (81.27 % female mortality). Results from mite contact toxicity showed that essential oil and extracts from L. nobilis were toxic to D. gallinae. Bay essential oil was both more toxic to mites, and faster in exerting this toxicity than other tested crude extracts. L. nobilis essential oil concentration leaded to enhance mortality of D. gallinae reaching the highest (100 %) mortality at 12 h with a concentration of 320 mg/mL. While, ethanolic extract acheived this rate after 24 h of exposure at same concentration. Cyclohexanic extract showed weak acaricidal activity.

Cross-sectional survey of cattle haemopathogens in Constantine, Northeast Algeria

This aim of the present study was to estimate the prevalence of haemopathogens in cattle in Beni Hamidene locality, district of Constantine (Νortheastern Algeria). Between June and October 2014, 169 bovines from 25 farms were included in this survey, 32 (18.9%) among them were suspected of piroplasmosis and/or anaplasmosis. Infection prevalences were estimated by microscopic examination of Giemsa‐stained blood smears and blood samples from all included cattle (n = 169). Animals were infected by Theileria annulata (65/169; 38.46%), Anaplasma marginale (22/169; 13%) and Babesia bovis (5/169; 3%). Two co‐infection patterns were found: Theileria annulata/Anaplasma marginale (7.69%) and Theileria annulata/Babesia bovis (1.18%). Only one farm had no cattle infected by any of the haemopathogens. There was a signification difference of T. annulata infection prevalence according to age category (p =.04). These results emphasised mainly the presence of bovine tropical theileriosis in northeastern, Beni Hamidene locality, province of Constantine, Algeria.

Identification and incidence of hard tick species during summer season 2019 in Jijel Province (northeastern Algeria)

Ticks are haematophagous arthropodsand tick-borne diseases causes billions of dollars in losses in the cattle industry because of the ability of ticks to be vector for many pathogens. This paper identifies and compares the infestation rate (prevalence and intensity) of females of hard tick species compared to males with respect to sex, age and breed of cattle in the region of Jijel, northeastern Algeria. A total of infested 53 cattle were screened and 1214 ticks were collected manually during summer 2019 (June, July and August) and identified based on their morphology. Seven tick species were identified as infesting the cattle: viz. Rhipicephalus (Boophilus) annulatus, Rhipicephalus bursa, Rhipicephalus sanguineus, Hyalomma marginatum, Hyalomma lusitanicum, Hyalomma scupense, and Hyalomma anatolicum. The predominant tick species recorded is Rhipicephalus (Boophilus) annulatus. The maximum intensity of tick infestation as a function of age is between 3 and 4 years and 5 and 6 years (39 ticks/cow). The study shows that the comparison between the prevalence of infestation in females and males is significant as a function of sex and breed of cattle. In addition, only the intensity of infestation as a function of the age of the cattle, when comparing the sexes of the ticks, is significant (p < 0.05). This study also provides data for the development of an active control plan based on tick mating strategies for the management of ticks in cattle in Jijel, Algeria.

Population Dynamics of Hyalomma dromedarii on Camels in the United Arab Emirates

Hyalomma dromedarii is the most important tick species infesting camels in the Middle East. So far, there are no studies on the population dynamics of H. dromedarii ticks on camels in the United Arab Emirates (UAE). Thus, the current study was performed: (1) to assess H. dromedarii population dynamics under common camel breeding and management practices in the study area, (2) to evaluate H. dromedarii life stage changes and sex ratio over time, and (3) to measure parasitological indicators of H. dromedarii infestation. We conducted monthly on-site tick visual counts and collection from camels in Al Ain, UAE, over 12 months. Our results show that the infestation prevalence was very high during the whole study period, with a mean of 94.33%. The maximum infestation intensity occurred in June, while the minimum occurred in January. Overall, H. dromedarii ticks were found on camels during the entire year in spite of monthly applications of an acaricide. This study reveals that H. dromedarii has a very high prevalence and continuous presence on camels in the UAE regardless of the weather fluctuations and acaricide applications and showed the need for an effective control strategy.

An insight into the ecobiology, vector significance and control of Hyalomma ticks (Acari: Ixodidae): A review

Ticks (Acari:Ixodoidea) are important ectoparasites infesting livestock and human populations around the globe. Ticks can cause damage directly by affecting the site of infestation, or indirectly as vectors of a wide range of protozoa, bacteria and viruses which ultimately lead to lowered productivity of livestock populations. Hyalomma is a genus of hard ticks, having more than 30 species well-adapted to hot, humid and cold climates. Habitat diversity, vector ability, and emerging problem of acaricidal resistance in enzootic regions typify this genus in various countries around the world. This paper reviews the epidemiology, associated risk factors (temperature, climate, age, sex, breed etc.), vector role, vector-pathogen association, and reported control strategies of genus Hyalomma. The various proteins in saliva of Hyalomma secreted into the blood stream of host and the prolonged attachment are responsible for the successful engorgement of female ticks in spite of host immune defense system. The various immunological approaches that have been tried by researchers in order to cause tick rejection are also discussed. In addition, the novel biological control approaches involving the use of entomo-pathogenic nematodes and Bacillus thuringiensis (B. thuringiensis) serovar thuringiensis H14; an endotoxin, for their acaricidal effect on different species and life cycle stages of Hyalomma are also presented.

Differences in tick infestation of Tunisian sheep breeds

Different infestation patterns by ixodid ticks were studied in three sheep breeds in Tunisia: Barbarine, Queue Fine de l'Ouest and their cross-bred animals. During one year, 700 sheep were monitored and examined for tick infestation. A total of 722 ticks were collected from sheep ears. The most frequent tick species was by far Rhipicephalus sanguineus sensu lato (99%) and there were few specimens of Rhipicephalus bursa (1%) (p < 0.001). Overall infestation prevalence was estimated at 10.4%. The lowest infestation prevalence was in Barbarine sheep (7.3%), followed by Queue Fine de l'Ouest (16.7%) and the highest prevalence was in cross-bred sheep (19.1%) (p < 0.001). Mean overall infestation intensity was 1.6 ticks/sheep: lowest in Barbarine (1.4), followed by Queue Fine de l'Ouest (1.7) and cross-bred sheep (1.8). Similarly, abundance was lowest in Barbarine sheep (0.1), and was 0.3 in Queue Fine de l'Ouest and cross-bred animals. The results demonstrated a reduced infestation, possibly due to reduced attractiveness and/or increased resistance to tick infestation, of the Barbarine breed compared with the other two breeds. Further behavioural, genetic and molecular studies are needed to explain the mechanisms for the lower infestation indicators.

Sero-epidemiological survey of Crimean-Congo hemorrhagic fever virus in Tunisia

Crimean-Congo hemorrhagic fever (CCHF) is a tick-borne disease associated with a high case fatality rate and transmitted mainly by Hyalomma marginatum. The geographical distribution of H. marginatum covers most of the Western Mediterranean basin. We aimed to investigate whether CCHF virus (CCHFv) is circulating in Tunisia. Samples from unexplained acute febrile patients (n = 181) and a high risk group of humans, mainly slaughter workers (n = 38), were collected in the summer of 2014 and analyzed for exposure to CCHFv using serological tests and real-time RT-PCR. Ticks were collected from Northern and Southern Tunisia during May–June 2014 and examined for the presence of CCHFv by real-time RT-PCR. Of the 181 febrile patients, 5 showed only high titers of IgM suggesting a recent exposure to CCHFv. Among 38 slaughter workers, 2 had IgG anti-CCHFv responses yielding a seroprevalence of 5.2%. No CCHFv was detected in ticks and sera. Our results provide evidence of human exposure to CCHFv in Tunisia.

A review of Hyalomma scupense (Acari, Ixodidae) in the Maghreb region: from biology to control

Hyalomma scupense (syn. Hyalomma detritum) is a two-host domestic endophilic tick of cattle and secondarily other ungulates in the Maghreb region (Africa). This species transmits several pathogens, among which two are major livestock diseases: Theileria annulata and Theileria equi. Various other pathogens are also transmitted by this tick species, such as Anaplasma phagocytophilum and Ehrlichia bovis. Hyalomma scupense is common in sub-humid and semi-arid areas of several regions in the world, mainly in the Maghreb region. In this region, adults attach to animals during the summer season; larvae and nymphs attach to their hosts during autumn, but there is a regional difference in H. scupense phenology. There is an overlap between immature and adult ticks, leading in some contexts to a dramatic modification of the epidemiology of tick-borne diseases. This tick species attaches preferentially to the posterior udder quarters and thighs. Tick burdens can reach 130 ticks per animal, with a mean of 60 ticks. Calves are 70 times less infested than adult cattle. The control can be implemented through six options: (i) rehabilitation of the farm buildings by roughcasting and smoothing the outer and inner surfaces of the enclosures and walls. This control option should be recommended to be combined with a thorough cleaning of the farm and its surrounding area. With regard to Theileria annulata infection, this control option is the most beneficial. (ii) Acaricide application to animals during the summer season, targeting adults. (iii) Acaricide application during the autumn period for the control of the immature stages. (iv) Acaricide application to the walls: many field veterinarians have suggested this option but it is only partially efficient since nymphs enter deep into the cracks and crevices. It should be used if there is a very high tick burden or if there is a high risk of tick-borne diseases. (v) Manual tick removal: this method is not efficient since the ticks can feed on several other animal species in the farm. This control option can lead to a reduction of the tick population, but not a decrease in tick-borne disease incidence. (vi) Vaccination: this control option consists of injecting the protein Hd86; trials have shown a partial effect on nymphs, with no effect on adult ticks. Combination of two of these control options is recommended in regions where there are high burdens of important tick vectors. Further studies are needed to improve our knowledge on this tick species in the Maghreb region, since the number of published studies on Hyalomma scupense in this region is very limited.