Current research in parasitology & vector-borne diseases最新文献

The genus Leptoconops Skuse (Diptera: Ceratopogonidae) are blood-sucking midges known to pester humans and domestic animals. In certain Mediterranean areas, midges occur in large numbers during summer and limit the use of recreational areas, also raising serious health and social concerns. Despite such impact, the diversity and distribution of Leptoconops in Maremma Regional Park (Tuscany Region, Italy), a heavily infested area, is not well known, and neither molecular nor detailed morphological studies exist. We sampled adult midge females in six areas and used high-resolution digital stereomicroscopy and scanning electron microscopy to identify species and investigate the morphology of structures involved in host searching/recognition (antennae and maxillary palps) and host attack (mouthparts). We also performed energy-dispersive X-ray spectroscopy to characterize the elemental composition of mouthparts. Finally, the cytochrome c oxidase subunit 1 (cox1) gene was amplified and sequenced, to confirm species identification of collected specimens. We identified two species: Leptoconops (L.) irritans Noé and Leptoconops (L.) noei Clastrier & Coluzzi, with the former being more frequently sampled than the latter and closer to sea coast and rivers. The antennal segments appeared slightly more globular in L. noei than in L. irritans. Five types of trichoid, basiconic and chaetic sensilla were found on the antennae, with some differences between the two species. Mouthparts had the labellum visibly larger in L. noei compared with L. irritans. The maxillary palps possessed a pit filled with bulb-shaped sensilla, which appeared denser in L. noei than in L. irritans. Mouthpart cuticle included Calcium (Ca) and Aluminum (Al) at small but significant concentrations (0.3–1.0%) in both species. Our results suggest that the limited but appreciable differences in sensory system between the studied species of Leptoconops and other Ceratopogonidae may reflect different host or habitat preferences, a scenario potentially suggested also by preliminarily data on their distribution in the studied area. The presence of Ca and Al in the cuticle of mouthparts may help host skin drilling during bite activity. Finally, the gene sequences obtained in this study provide a first reference for future investigations on the taxonomy and dispersal patterns of Leptoconops spp. in the Mediterranean area.

Due to the close bond between humans and companion animals, a thorough understanding of the diversity of Cryptosporidium species and Giardia assemblages in cats and dogs is essential to determine the potential zoonotic risks. Analysis of molecular studies shows that C. felis and C. canis are the main species infecting cats and dogs, respectively. These species are largely host-specific, as despite intense association with humans, prevalence of C. felis and C. canis in humans is low and predominantly in immunocompromised individuals and low-income countries. There have been reports of C. parvum in cats and dogs and two reports of C. hominis in dogs. In most studies conducted to date, however, the prevalence of zoonotic species was low and may be associated with coprophagy and or/spillback, but this remains to be determined. Results of subtyping studies suggest that for C. felis and C. canis, some zoonotic transmission may occur but host-adapted subtypes also exist. Giardia duodenalis assemblages C and D are commonly reported in dogs, with assemblages F and A most common in cats. Assemblages C, D and F are largely host-specific as there are only a handful of reports of them in humans. Reports of assemblage A and B in cats and dogs may be due to coprophagy or spillback from owners. Despite the extent of pet ownership and the close contact between humans and companion animals worldwide, the overall risk of zoonotic transmission from cats and dogs to humans is uncertain but thought to be low due to C. canis, C. felis and G. duodenalis assemblages C, D and F being predominantly host-specific, the relatively low prevalence of C. parvum (and C. hominis) in cats and dogs (which may be due to mechanical carriage), and low oo/cyst shedding. Carefully designed epidemiological studies of cats and dogs and their owners using subtyping tools are essential to better quantify the extent of spillover and spillback of Cryptosporidium and Giardia between pets and their owners.

The miticide efficacy of a single treatment with Felpreva® (tigolaner, emodepside and praziquantel) spot-on solution for cats was evaluated in two European field studies. One study was conducted in cats naturally infested with Otodectes cynotis. The other study was conducted in cats naturally infested with Notoedres cati. In both studies, the presence of viable mites was confirmed prior to treatment (Day -1/Day 0) and re-evaluated on Day 14 (O. cynotis study) and on Day 28 (both studies). Efficacy was calculated based on the number of viable mites found after treatment. In the O. cynotis study, the primary criterion was the percentage of mite-free cats after treatment with Felpreva® compared to a sarolaner/selamectin combination (Stronghold® Plus, Zoetis) as a positive control. In the N. cati study, the primary criterion was the difference between arithmetic mean mite counts of cats treated with Felpreva® and cats treated with a placebo formulation (solketal). Secondary criteria in both studies were changes in clinical lesion scores after treatment. In both studies, all Felpreva®-treated cats were mite-free (100% parasitological cure) on Day 28, 4 weeks after treatment. Signs of mange on Day 28 were clinically improved in all O. cynotis-infested cats (100%) and clinically cured in all N. cati-infested cats (100%). There were no records of any adverse events or application site reactions in Felpreva®-treated cats.

Visceral and cutaneous leishmaniases are important public health concerns in Cyprus. Although the diseases, historically prevalent on the island, were nearly eradicated by 1996, an increase in frequency and geographical spread has recently been recorded. Upward trends in leishmaniasis prevalence have largely been attributed to environmental changes that amplify the abundance and activity of its vector, the phlebotomine sand flies. Here, we performed an extensive field study across the island to map the sand fly fauna and compared the presence and distribution of the species found with historical records. We mapped the habitat preferences of Phlebotomus papatasi and P. tobbi, two medically important species, and predicted the seasonal abundance of P. papatasi at unprecedented spatiotemporal resolution using a climate-sensitive population dynamics model driven by high-resolution meteorological forecasting. Our compendium holds a record of 18 species and the locations of a subset, including those of potential public and veterinary health concern. We confirmed that P. papatasi is widespread, especially in densely urbanized areas, and predicted that its abundance uniformly peaks across the island at the end of summer. We identified potential hotspots of P. papatasi activity even after this peak. Our results form a foundation to inform public health planning and contribute to the development of effective, efficient, and environmentally sensitive strategies to control sand fly populations and prevent sand fly-borne diseases.

Tularemia is a rare but potentially serious bacterial zoonosis, which has been reported in the 47 contiguous states of the USA during 2001–2010. This report summarizes the passive surveillance data of tularemia cases reported to the Centers for Disease Control and Prevention from 2011 through 2019. There were 1984 cases reported in the USA during this period. The average national incidence was 0.07 cases per 100,000 person-years (PY), compared to 0.04 cases per 100,000 PY during 2001–2010. The highest statewide reported case 2011–2019 was in Arkansas (374 cases, 20.4% of total), followed by Missouri (13.1%), Oklahoma (11.9%), and Kansas (11.2%). Regarding race, ethnicity, and sex, tularemia cases were reported more frequently among white, non-Hispanic, and male patients. Cases were reported in all age groups; however, individuals 65 years-old and older exhibited the highest incidence. The seasonal distribution of cases generally paralleled the seasonality of tick activity and human outdoor activity, increasing during spring through mid-summer and decreasing through late summer and fall to winter lows. Improved surveillance and education of ticks and tick- and water-borne pathogens should play a key role in efforts to decrease the incidence of tularemia in the USA.

Mosquitoes can impact military operational readiness by transmission of disease-causing pathogens or through secondary effects, e.g., annoyance and bites. The focus of this research was to determine if an array of novel controlled release passive devices (CRPD) utilizing the spatial repellent, transfluthrin (TF), as the active ingredient could prevent entry of mosquitoes into military tents for up to 4 weeks. The TF-charged CRPDs were spaced along six strands of monofilament and hung across the tent entrance. Efficacy was evaluated with caged Aedes aegypti to indicate knockdown/mortality effects, and four species of free-flying mosquitoes, Ae. aegypti, Aedes taeniorhynchus, Anopheles quadrimaculatus and Culex quinquefasciatus, to indicate repellent effects. Bioassay cages containing Ae. aegypti were hung vertically at 0.5, 1.0 and 1.5 ​m above ground level at designated locations inside of the tents. Knockdown/mortality counts were made every 15 min for the first hour, then at 2, 4 and 24 h post-exposure. Free fliers were recaptured in BG traps operated from 4 to 24 h post-exposure. Knockdown/mortality was gradual until 4 h post-exposure. This increased to near 100% by 24 h in the treated tent but was < 2% in the control tent. There was a significant reduction in the recapture rates of all free-flying species in the treated tent compared with the control tent. Results indicate that TF-charged CRPDs can significantly reduce the numbers of mosquitoes entering military tents and that the four species were affected similarly by the TF. The needs for additional research are discussed.

Experimental hut trials (EHTs) are used to evaluate indoor vector control interventions against malaria vectors in a controlled setting. The level of variability present in the assay will influence whether a given study is well powered to answer the research question being considered. We utilised disaggregated data from 15 previous EHTs to gain insight into the behaviour typically observed. Using simulations from generalised linear mixed models to obtain power estimates for EHTs, we show how factors such as the number of mosquitoes entering the huts each night and the magnitude of included random effects can influence study power. A wide variation in behaviour is observed in both the mean number of mosquitoes collected per hut per night (ranging from 1.6 to 32.5) and overdispersion in mosquito mortality. This variability in mortality is substantially greater than would be expected by chance and should be included in all statistical analyses to prevent false precision of results. We utilise both superiority and non-inferiority trials to illustrate our methodology, using mosquito mortality as the outcome of interest. The framework allows the measurement error of the assay to be reliably assessed and enables the identification of outlier results which could warrant further investigation. EHTs are increasingly playing an important role in the evaluation and regulation of indoor vector control interventions so it is important to ensure that these studies are adequately powered.

A recent phylogenetic analysis of Triatoma pallidipennis, an important Chagas disease vector in Mexico, based on molecular markers, revealed five monophyletic haplogroups with validity as cryptic species. Here, we compare T. pallidipennis haplogroups using head and pronotum features, environmental characteristics of their habitats, and ecological niche modeling. To analyze variation in shape, images of the head and pronotum of the specimens were obtained and analyzed using methods based on landmarks and semi-landmarks. Ecological niche models were obtained from occurrence data, as well as a set of bioclimatic variables that characterized the environmental niche of each analyzed haplogroup. Deformation grids for head showed a slight displacement towards posterior region of pre-ocular landmarks. Greatest change in head shape was observed with strong displacement towards anterior region of antenniferous tubercle. Procrustes ANOVA and pairwise comparisons showed differences in mean head shape in almost all haplogroups. However, pairwise comparisons of mean pronotum shape only showed differences among three haplogroups. Correct classification of all haplogroups was not possible using discriminant analysis. Important differences were found among the environmental niches of the analyzed haplogroups. Ecological niche models of each haplogroup did not predict the climatic suitability areas of the other haplogroups, revealing differences in environmental conditions. Significant differences were found between at least two haplogroups, demonstrating distinct environmental preferences among them. Our results show how the analysis of morphometric variation and the characterization of the environmental conditions that define the climatic niche can be used to improve the delimitation of T. pallidipennis haplogroups that constitute cryptic species.

Heartworm disease in dogs and cats caused by Dirofilaria immitis continues to be a major clinical issue globally. This study focused on dogs suspicious of having tick-borne diseases (TBD) brought to a clinic and a veterinary teaching hospital in Myanmar. Blood samples were collected and initially screened using SNAP® 4Dx® Plus test kit. All dog blood samples were subjected to conventional PCR to detect both Dirofilaria spp. (cox1 gene) and Wolbachia spp. (16S rDNA) infections. Infection with D. immitis was detected in 14 (28.0%) of 50 examined samples, while the detection rate of TBD causative agents, including Anaplasma phagocytophilum and Ehrlichia canis, was 26.0% (13/50) and 26.0% (13/50), respectively, as determined by ELISA rapid test. In this study, D. immitis infection was moderately but significantly correlated with TBD infections (Pearson’s r = 0.397, P = 0.008). Comparative sequence and phylogenetic analyses provided molecular identification of D. immitis in Myanmar and confirmed the identity of its Wolbachia endosymbiont with Wolbachia endosymbionts isolated from D. immitis, Rhipicephalus sanguineus and Aedes aegypti. The present study contributes to our understanding of the coexistence of D. immitis and Wolbachia endosymbiosis in dogs, and the findings may benefit the future prevention and control of dirofilariasis in dogs.

Cryptosporidium spp. are widespread parasitic protozoans causing enteric infections in humans and animals. The parasites cause neonatal diarrhoea in calves, leading to a high mortality rate in the first three weeks. Losses are significant for farmers, but the cost of cryptosporidiosis remains poorly documented. In the absence of a vaccine, only preventive measures are available to farmers to combat the infection. This study, conducted between 2018 and 2021, aimed to evaluate the economic impact of Cryptosporidium spp. on European dairy farms and monitor changes in costs after implementing disease management measures. First, a field survey was carried out and questionnaires administered to 57 farmers in Belgium, France, and the Netherlands. The aim of the survey was to assess the losses associated with the occurrence of diarrhoea in calves aged between 3 days and 3 weeks. The economic impact of diarrhoea was calculated based on mortality losses, health expenditures, and additional labour costs. To refine the cost estimation specifically for Cryptosporidium spp., stool samples were collected from 10 calves per farm. The prevalence of Cryptosporidium spp. was determined, and the economic impact of diarrhoea was adjusted accordingly. The assumption was made that a certain percentage of costs was attributed to cryptosporidiosis based on the prevalence. These protocols were repeated at the end of the study to observe changes in costs. In the three years, the cost of diarrhoea for the 28 farms that stayed in the panel all along the study improved from €140 in 2018 to €106 on average per diarrhoeic calf in 2021. With a stable prevalence at 40%, the cost of cryptosporidiosis per infected calf decreased from €60.62 to €45.91 in Belgium, from €43.83 to €32.14 in France, and from €58.24 to €39.48 in the Netherlands. This represented an average of €15 saved per infected calf. The methodology employed in this study did not allow us to conclude that the improvement is strictly due to the implementation of preventive measures. However, with 11 million calves raised in the Interreg 2 Seas area covered by the study, it provided valuable insights into the economic burden of Cryptosporidium spp.