Interrupted Blood Feeding in Ticks: Causes and Consequences

Ticks are obligate hematophagous arthropods and act as vectors for a great variety of pathogens, including viruses, bacteria, protozoa, and helminths. Some tick-borne viruses, such as Powassan virus and tick-borne encephalitis virus, are transmissible within 15–60 min after tick attachment. However, a minimum of 3–24 h of tick attachment is necessary to effectively transmit bacterial agents such as Ehrlichia spp., Anaplasma spp., and Rickettsia spp. to a new host. Longer transmission periods were reported for Borrelia spp. and protozoans such as Babesia spp., which require a minimum duration of 24–48 h of tick attachment for maturation and migration of the pathogen. Laboratory observations indicate that the probability of transmission of tick-borne pathogens increases with the duration an infected tick is allowed to remain attached to the host. However, the transmission time may be shortened when partially fed infected ticks detach from their initial host and reattach to a new host, on which they complete their engorgement. For example, early transmission of tick-borne pathogens (e.g., Rickettsia rickettsii, Borrelia burgdorferi, and Brucella canis) and a significantly shorter transmission time were demonstrated in laboratory experiments by interrupted blood feeding. The relevance of such situations under field conditions remains poorly documented. In this review, we explore parameters of, and causes leading to, spontaneous interrupted feeding in nature, as well as the effects of this behavior on the minimum time required for transmission of tick-borne pathogens

Vectra 3D (dinotefuran, pyriproxyfen and permethrin) prevents acquisition of Borrelia burgdorferi sensu stricto by Ixodes ricinus and Ixodes scapularis ticks in an ex vivo feeding model

BACKROUND: We evaluated the efciency of an ex vivo feeding technique using a silicone membrane-based feeding chamber to (i) assess the anti-feeding and acaricidal efcacy of a spot-on combination of dinotefuran, pyriproxyfen and permethrin (DPP, Vectra® 3D) against adult Ixodes scapularis and Ixodes ricinus ticks, and to (ii) explore its efect on blocking the acquisition of Borrelia burgdorferi sensu stricto. METHODS: Eight purpose-bred dogs were randomly allocated to two equal-size groups based on body weight assessed on day 2. DPP was administered topically, as spot-on, to four dogs on day 0. Hair from the eight dogs was collected individually by brushing the whole body on days 2, 7, 14, 21, 28 and 35. On each day of hair collection, 0.05 g of sampled hair was applied on the membrane corresponding to each feeding unit (FU). Seventy-two FU were each seeded with 30 adults of I. scapularis (n=24 FU) or I. ricinus ticks (n=48 FU). Bovine blood spiked with B. burgdorferi sensu stricto (strain B31) was added into each unit and changed every 12 h for 4 days. Tick mortality was assessed 1 h after seeding. One additional hour of incubation was added for live/moribund specimens and reassessed for viability. All remaining live/moribund ticks were left in the feeders and tick engorgement status was recorded at 96 h after seeding, and the uptake of B. burgdorferi s.s. was examined in the collected ticks by applying quantitative real-time PCR. RESULTS: Exposure to DPP-treated hair was 100% efective in blocking B. burgdorferi s.s. acquisition. The anti-feeding efcacy remained stable (100%) against both Ixodes species throughout the study. The acaricidal efcacy of DPP evaluated at 1 and 2 h after exposure was 100% throughout the study for I. ricinus, except the 1-h assessment on day 28 (95.9%) and day 35 (95.3%). The 1-h assessment of acaricidal efcacy was 100% at all time points for I. scapularis. CONCLUSIONS: The ex vivo feeding system developed here demonstrated a protective efect of DPP against the acquisition of B. burgdorferi without exposing the animals to the vectors or to the pathogen.Ceva Santé Animalehttps://parasitesandvectors.biomedcentral.compm2022Veterinary Tropical Disease

Mosquitoes and dirofilariasis : development and use of innovative tools for detection and monitoring

Dans ce travail, nous nous sommes intéressés à l’étude des dirofilarioses chez le réservoir canin « le chien » ainsi que chez les vecteurs « moustiques », en particulier, en ce qui concerne la détection, la surveillance et la prophylaxie. Le premier objectif était de développer une PCR duplex en temps réel ciblant le gène COI capable de détecter et de différencier simultanément D. immitis et D. repens. Ainsi, nous avons détecté par cet outil moléculaire, pour la première fois en France, D. immitis et D. repens chez des moustiques tigre "Aedes albopictus". Nous avons, de plus, confirmé la présence de l’infection à D. immitis chez les chiens du nord d'Algérie.Le deuxième objectif était d'évaluer l’intérêt de la spectrométrie de masse MALDI-TOF MS pour la détection de changements dans les profils protéiques d'Aedes aegypti infectés expérimentalement avec des nématodes filaires (D. immitis, Brugia malayi et B. pahangi). Les résultats obtenus montrent la capacité du MALDI-TOF MS à différencier des moustiques infectés et non infectés par les filaires. Ainsi, les meilleurs taux de classification correcte obtenus sont 94,1, 86,6, 71,4 et 68,7% pour les non infectés versus ceux infectés, respectivement, par D. immitis, B. malayi et B. pahangi.Le troisième objectif de ce travail était l’évaluation de l'efficacité anti-gorgement et insecticide d'un ectoparasiticide (Vectra® 3D) contenant trois principes actifs : le dinotéfurane, le pyriproxyfène et la perméthrine contre Ae. albopictus, l'une des principales espèces vectrices de Dirofilaria spp. Les résultats ont démontré que le DPP a une efficacité anti-gorgement et insecticide significative contre Ae. albopictusIn this work, we are interested in studying dirofilarial infections in dogs and vectors “Mosquitoes” especially detection, monitoring and prophylaxis. The first objective is to develop a real-time duplex PCR targeting the COI gene capable of simultaneously detecting and differentiating D. immitis and D. repens. Subsequently, we applied this tool to a canine dirofilariosis surveillance process in different endemic areas of Mediterranean basin (Corsica and Algeria). We have thus detected by this molecular tool for the first time in France, D. immitis and D. repens in Aedes albopictus mosquitoes. We reported, also, the presence of D. immitis in dogs from northern Algeria.The second aim was to assess whether the MALDI-TOF MS can detect changes in the protein profiles of Aedes aegypti infected experimentaly with filarial nematodes (D. immitis, Brugia malayi and B. pahangi). Obtained results showed the potential of MALDI-TOF MS as a reliable tool for differentiating non-infected and filariae-infected Ae. aegypti mosquitoes with a best correct classification rate obtained from the thorax-head part with 94.1 and 86.6, 71.4 and 68.7% for non-infected and D. immitis, B. malayi and B. pahangi infected mosquitoes respectively.The third aim of this work has focused on the evaluation of the anti-feeding and insecticidal efficacy of an ectoparasiticide (Vectra® 3D) containing three active ingredients: dinotefurane, pyriproxyfen and permethrin (DPP) against Ae. albopictus. Results demonstrated that the DPP combination has significant anti-feeding and insecticidal efficacy against Ae. albopictus for at least 4 weeks

Vector-borne nematode diseases in pets and humans in the Mediterranean Basin: An update

International audienc

First molecular detection of Dirofilaria immitis (Spirurida: Onchocercidae) infection in dogs from Northern Algeria

International audienceDirofilaria immitis and Dirofilaria repens are mosquito-borne filarioid nematodes that affect dogs and other domestic and wild carnivores, causing heartworm disease and subcutaneous dirofilariosis, respectively. In Algeria, the data about the epidemiology of these infections is largely unknown. The present study was designed to establish the occurrence of D. immitis and D. repens in dogs in Algeria using molecular tools. In 2014 and 2015, a total of 209 dogs over one year of age of different breed and sex, living in Northern Algeria, were examined and blood samples were collected from each dog. The presence of D. immitis and D. repens in these samples was detected by real-time PCR followed by standard PCR and sequencing. Overall, the blood of 209 dogs from two departments was collected and only 3 (1.4%) of the blood samples were found positive for D. immitis DNA. Sequencing of the corresponding amplicon displayed a 99.8% identity to D. immitis, confirming the presence of this mosquito-borne nematode in Algeria. Furthermore, all tested samples were negative for D. repens

Molecular investigation and phylogeny of Anaplasmataceae species infecting domestic animals and ticks in Corsica, France

Abstract Backgrounds Corsica is a French island situated in the Mediterranean Sea. The island provides suitable natural conditions to study disease ecology, especially tick-borne diseases and emerging diseases in animals and ticks. The family Anaplasmataceae is a member of the order Rickettsiales; it includes the genera Anaplasma, Ehrlichia, Neorickettsia and Wolbachia. Anaplasmosis and ehrlichiosis traditionally refer to diseases caused by obligate intracellular bacteria of the genera Anaplasma and Ehrlichia. The aim of this study was to identify and estimate the prevalence of Anaplasmataceae species infecting domestic animals and ticks in Corsica. Methods In this study, 458 blood samples from sheep, cattle, horses, goats, dogs, and 123 ticks removed from cattle, were collected in Corsica. Quantitative real-time PCR screening and genetic characterisation of Anaplasmataceae bacteria were based on the 23S rRNA, rpoB and groEl genes. Results Two tick species were collected in the present study: Rhipicephalus bursa (118) and Hyalomma marginatum marginatum (5). Molecular investigation showed that 32.1% (147/458) of blood samples were positive for Anaplasmataceae infection. Anaplasma ovis was identified in 42.3% (93/220) of sheep. Anaplasma marginale was amplified from 100% (12/12) of cattle and two R. bursa (2/123). Several potentially new species were also identified: Anaplasma cf. ovis, “Candidatus Anaplasma corsicanum”, “Candidatus Anaplasma mediterraneum” were amplified from 17.3% (38/220) of sheep, and Anaplasma sp. marginale-like was amplified from 80% (4/5) of goats. Finally, one R. bursa tick was found to harbour the DNA of E. canis. All samples from horses and dogs were negative for Anaplasmataceae infection. Conclusions To our knowledge, this study is the first epidemiological survey on Anaplasmataceae species infecting animals and ticks in Corsica and contributes toward the identification of current Anaplasmataceae species circulating in Corsica

Assessment of MALDI-TOF mass spectrometry for filariae detection in Aedes aegypti mosquitoes.

Matrix Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) is an emerging tool for routine identification of bacteria, archaea and fungi. It has also been recently applied as an accurate approach for arthropod identification. Preliminary studies have shown that the MALDI-TOF MS was able to differentiate whether ticks and mosquitoes were infected or not with some bacteria and Plasmodium parasites, respectively. The aim of the present study was to test the efficiency of MALDI-TOF MS tool in distinguishing protein profiles between uninfected mosquitoes from specimens infected by filarioid helminths. Aedes aegypti mosquitoes were engorged on microfilaremic blood infected with Dirofilaria immitis, Brugia malayi or Brugia pahangi. Fifteen days post-infective blood feeding, a total of 534 mosquitoes were killed by freezing. To assess mass spectra (MS) profile changes following filariae infections, one compartment (legs, thorax, head or thorax and head) per mosquito was submitted for MALDI-TOF MS analysis; the remaining body parts were used to establish filariae infectious status by real-time qPCR. A database of reference MS, based on the mass profiles of at least two individual mosquitoes per compartment, was created. Subsequently, the remaining compartment spectra (N = 350) from Ae. aegypti infected or not infected by filariae were blind tested against the spectral database. In total, 37 discriminating peak masses ranging from 2062 to 14869 daltons were identified, of which 17, 11, 12 and 7 peak masses were for legs, thorax, thorax-head and head respectively. Two peak masses (4073 and 8847 Da) were specific to spectra from Ae. aegypti infected with filariae, regardless of nematode species or mosquito compartment. The thorax-head part provided better classification with a specificity of 94.1% and sensitivity of 86.6, 71.4 and 68.7% of D. immitis, B. malayi and B. pahangi respectively. This study presents the potential of MALDI-TOF MS as a reliable tool for differentiating non-infected and filariae-infected Ae. aegypti mosquitoes. Considering that the results might vary in other mosquito species, further studies are needed to consolidate the obtained preliminary results before applying this tool in entomological surveillance as a fast mass screening method of filariosis vectors in endemic areas

Effect of Dinotefuran, Permethrin, and Pyriproxyfen (Vectra (R) 3D) on the Foraging and Blood-Feeding Behaviors of Aedes albopictus Using Laboratory Rodent Model

International audienceDinotefuran-Permethrin-Pyriproxyfen (DPP) is used to kill and repel mosquitoes from dogs. However, the influence of the product on the host-seeking behavior of mosquitoes remains unknown. The interference of DPP with the host selection of unfed female Aedes albopictus was investigated. A total of 18 animals (9 mice and 9 rats) were divided into three groups of six animals each. DU: DPP treated rats (n = 3) with untreated mice (n = 3), UD: DPP treated mice (n = 3) with untreated rats (n = 3) and control UU: untreated mice (n = 3) and untreated rats (n = 3). In each group, the rats and mice were placed 30 cm apart. After sedation, the animals in each group were exposed twice (Day 1 and Day 7 post-treatment) for one hour to 71 +/- 3 female mosquitoes. Mosquitoes were categorized after the 2-h post-exposure period as dead or alive. Blood-meal origin was determined from mosquitoes using a newly customized duplex qPCR. The highest values of forage ratio (1.36 >= wi >= 1.88) and selection index (0.63 >= Bi >= 0.94) for rat hosts indicates a preference of mosquitoes for this species as compared to mice when co-housed during the exposure. The mosquitoes only seldom fed on mice, even in the untreated group. The anti-feeding effect of DPP was therefore only assessed on rat's hosts. The results showed that DPP, when directly applied on rats, provided a direct protection of 82% and 61% on Day 1 and Day 7, respectively, while when applied on mice hosts (UD), the DPP provided an indirect protection of 21% and 10% on Day 1 and Day 7, respectively. The results showed also that DPP, when applied on rats, provided a direct protection against Ae. albopictus bites. This effect did not result in increased exposure of the untreated host placed in the same cage at a distance of 30 cm

Broad diversity of Mycobacterium tuberculosis complex strains isolated from humans and cattle in Northern Algeria suggests a zoonotic transmission cycle.

Mycobacterium tuberculosis complex (MTBC) comprises closely related species responsible for human and animal tuberculosis (TB). Efficient species determination is useful for epidemiological purposes, especially for the elucidation of the zoonotic contribution. In Algeria, data on MTBC genotypes are largely unknown. In this study, we aimed to investigate the occurrence and diversity of MTBC genotypes causing human and bovine TB in Northern Algeria. During a two-year sampling period (2017-2019) in two regions of Northern Algeria, we observed an overall prevalence of 6.5% of tuberculosis (TB) among slaughtered cattle, which is higher than previous Algerian data yet comparable to neighboring countries. A total of 296 Mycobacterium tuberculosis complex (MTBC) isolates were genotyped by spoligotyping: 181 from tissues with TB-like lesions collected from 181 cattle carcasses and 115 from TB patients. In human isolates, we identified 107 M. tuberculosis, seven M. bovis and one "M. pinnipedii-like", while for bovine samples, 174 isolates were identified as M. bovis, three as M. caprae, three as "M. pinnipedii-like" and one as "M. microti-like". The majority of isolates (89.2%) belonged to 72 different known Shared International Types (SIT) or M. bovis spoligotypes (SB), while we also identified seven new SB profiles (SB2695 to SB2701). Twenty-eight of the SB profiles were new to Algeria. Our data suggest zoonotic transmission in Sétif, where significantly more TB was observed among cattle (20%) compared to the slaughterhouses from the three other regions (5.4%-7.3%) (p < 0.0001), with the isolation of the same M. bovis genotypes from TB patients. The present study showed a high genetic diversity of MTBC isolated from human and cattle in Northern Algeria. Even though relatively small in terms of numbers, our data suggest the zoonotic transmission of TB from cattle to humans, suggesting the need for stronger eradication strategies for bovine TB