Parasites & Vectors最新文献

Background: Pig breeding is a crucial sector of the global economy, playing a significant role in meat production. However, the prevalence of Trichomonas spp., a group of parasites known to induce diarrhea in various hosts, presents significant challenges in breeding facilities. These parasites pose a substantial threat to the pig breeding industry. Furthermore, despite its prevalence, diagnosing Trichomonas spp. is often challenging, primarily owing to the presence of mixed infections involving different species within clinical samples. To address this concern, we developed a novel isolation method that combines a single-cell isolation culture technique with an antimicrobial drug susceptibility test.

Methods: Trichomonas was isolated and cultured by using the established single-worm separation technology combined with antibacterial drug screening method, and it was identified as Pentatrichomonas hominis by molecular biological identification and morphological identification. The in vitro culture conditions of the isolate were optimized to establish a stable in vitro culture system.

Results: The method developed in this study was effective in successfully isolating a pure species of trichomonad from fecal samples obtained from weaned piglets in Guangdong Province. By optimizing important variables such as the culture medium, serum type, and inoculum quantity, we established a stable in vitro culture system utilizing a modified Diamond medium supplemented with 10% Procell fetal bovine serum without the use of antibiotics. Subsequent analysis of the isolate's 18S rRNA gene, ITS1-5.8S rRNA-ITS2 gene, and EF-α gene, through polymerase chain reaction, DNA sequencing, and phylogenetic analysis, revealed its close association to Pentatrichomonas hominis. Light microscopy and scanning electron microscopy demonstrated the presence of various distinct cellular structures, including four anterior flagella, recurrent flagellum, undulating membrane, pelta and axostyle. Additionally, transmission electron microscopy revealed the existence of organelles such as the Golgi complex, rough endoplasmic reticulum, food vacuoles, and hydrogenosomes. This study represents the first successful isolation of monoclonal cells of P. hominis to our knowledge and serves as a valuable baseline for future research focused on the isolation and purification of various other parasites. Additionally, it offers practical guidance for the diagnosis and management of Trichomonas spp. infections in pigs.

Conclusions: In summary, our findings underscore the efficacy of our novel isolation technique as a valuable tool for the diagnosis and management of Trichomonas spp. infections, which can help mitigate the significant economic losses encountered in the pig breeding industry.

Background: Soil is a reservoir for many parasites that can affect human and animal health, especially in tropical regions where soil-transmitted helminths and protozoa thrive. Understanding how environmental factors influence parasite distribution will provide a basis for relating how climate changes may intensify their impacts, altering parasite habitats and increasing transmission risks. We surveyed soil parasite prevalence, burden, and diversity in several different Peruvian environmental ecologies to catalog current parasite presence and provide a baseline for future surveys.

Methods: A total of 198 soil samples from 43 locations across three Peruvian regions-Tingo María (TM) (Amazon rainforest), Andabamba/Marabamba (A/M) (Andean highlands), and Huánuco city parks-were analyzed using multi-parallel quantitative real-time polymerase chain reaction (qPCR) to detect soil-transmitted helminths (STH) and protozoan DNA from entry, patio, and latrine sites.

Results: Parasites were detected in 93% of locations, with 84% showing polyparasitism. TM houses had a higher odds ratio of contamination with Ascaris lumbricoides and Trichuris trichiura than those in A/M. TM also showed significantly higher odds of helminth contamination in patios than entries. TM had significantly more parasite species, with helminth species significantly higher in the patio versus entry. A/M had higher protozoan prevalence with Blastocystis species, with a greater odd ratios to TM. A/M had an increase of Acanthamoeba species in patios versus entries, indicating a niche favoring protozoans in these arid conditions.

Conclusions: The observed variability in soil parasite prevalence between tropical rainforest and highland regions highlights the influence of environmental niches on parasite distribution, which may shift further due to climate change. This study demonstrates a sensitive approach to monitoring environmental contamination with parasites by leveraging qPCR. The findings underscore the importance of ecological surveillance for assessing parasitic transmission risks, which is crucial for guiding public health interventions, especially as environmental changes accelerate.

Background: Culex theileri (Theobald, 1903) is distributed in Afrotropical, Paleartic, and Oriental regions. It is a mainly mammophilic floodwater mosquito that is involved in the transmission of West Nile virus (WNV, renamed as Orthoflavivirus nilense by the International Committee on Taxonomy of Viruses [ICTV]) in Africa. This virus is a mosquito-borne flavivirus that is kept in an enzootic cycle mainly between birds and mosquitoes of the Culex genus. Occasionally, it affects mammals including humans and equines causing encephalopathies. The main purpose of the present study was to evaluate the vector competence of a European field-captured Cx. theileri population for circulating WNV lineages (1 and 2).

Methods: Field-collected Cx. theileri larvae from Sevilla province (Spain) were reared in the laboratory under summer environmental conditions. To assess the vector competence for WNV transmission, 10-12 day old Cx. theileri females were fed with blood doped with WNV lineages 1 and 2 (7 log₁₀ TCID₅₀/mL). Females were sacrificed at 14- and 21- days post exposure (dpe), and their head, body, and saliva were extracted to assess infection, dissemination, and transmission rates, as well as transmission efficiency.

Results: A Culex theileri population was experimentally confirmed as a highly competent vector for WNV (both lineages 1 and 2). The virus successfully infected and disseminated within Cx. theileri mosquitoes, and infectious virus isolated from their saliva indicated their potential to transmit the virus. Transmission efficiency was 50% for lineage 1 (for both 14 and 21 dpe), while it was 24% and 37.5% for lineage 2, respectively. There was barely any effect of the midgut infection barrier for lineage 1 and a moderate effect for lineage 2. The main barrier which limited the virus infection within the mosquito was the midgut escape barrier.

Conclusions: In the present study, the high transmission efficiency supports that Cx. theileri is competent to transmit WNV. However, vector density and feeding patterns of Cx. theileri mosquitoes must be considered when estimating their vectorial capacity for WNV in the field.

Background: Triatoma brasiliensis brasiliensis is the primary vector of Chagas disease in Brazil's semi-arid regions, exhibiting adaptability to various environments, including domestic and peridomestic. Despite its significance, comprehensive genomic data for this subspecies remain limited.

Methods: We assembled the complete mitochondrial genome of T. b. brasiliensis using a combination of Illumina and Sanger sequencing technologies, the latter being necessary to obtain the control region with eight primers designed in this study. The mitogenome was annotated to identify gene content and organization. Phylogenetic relationships were inferred using conserved blocks of 13 protein-coding genes and 22 transfer RNA genes. For this analysis, 18 representative triatomines with near-complete mitogenomes were selected, and phylogenetic reconstruction was performed using the maximum ikelihood method.

Results: The complete mitogenome spans 16,575 base pairs and includes 13 protein-coding genes, 22 transfer RNA genes, and two ribosomal RNA genes, consistent with the typical structure of insect mitochondrial genomes. The control region exhibited tandem and inverted repeats arranged in blocks, as observed for other Reduviidae. Given the limited availability of mitogenomes, our phylogenetic analysis provided statistical support for T. b. brasiliensis as a sister taxon to Triatoma infestans, forming a well-supported clade that is sister to Triatoma vitticeps.

Conclusions: The availability of this mitogenome provides insights into the systematics, biology, and genomics of triatomine species while also enhancing our understanding of their evolutionary relationships. However, the limited number of available mitogenomes, particularly for South American Triatoma species, underscores the need for further sequencing efforts to improve phylogenetic resolution and support comparative genomic studies.

Background: Insects belonging to the Siphonaptera order are obligatory ectoparasites of vertebrates, including humans. Their life cycle is marked by holometabolous development, and adults are adapted to have a bloodmeal out of their hosts. The objective of this study is to review the families occurring in Brazil with their species and report new records from fleas collected in an Atlantic Rainforest preserved area, including Rickettsia sp. monitoring.

Methods: Literature research was carried out, including journal articles and books available in scientific databases. The sample collection took place at Legado das Águas-Reserva Votorantim private reserve, where wild rodents, marsupials, and bats were captured and inspected for the presence of fleas. The fleas were identified, and their genetic material was extracted and subjected to two polymerase chain reactions (PCRs): an endogenous control to validate the extraction and a Rickettsia screening.

Results: A total of 8 families were reviewed, resulting in 63 valid species that interact with a wide range of hosts. Among the collected fleas, 7 species were identified as interacting with 19 different host genera belonging to the Rodentia, Didelphimorphia, and Chiroptera orders. We highlight the presence of 2 new locality records and 15 new host interactions. Of the collected fleas, 105 specimens were tested individually for Rickettsia bacteria, but none showed expected amplicons for the bacterium.

Conclusions: This study provides an extensive revision of the Siphonaptera order present in Brazil with new insights, since the last robust revision made was from 2000, along with new information regarding host association and locality based on field collections conducted by the authors, which helps understanding the host-parasite interaction and encourages new studies.

Background: Angiostrongylus cantonensis is a food-borne parasite that can infect mammals, including humans, causing angiostrongyliasis. The nuclear factor E2-related factor 2 (Nrf2) is a transcription factor that plays a crucial role in the host's antioxidant defense and inflammation mechanisms. Herein, this study investigates the anti-inflammatory effects of Nrf2 in A. cantonensis-induced parasitic meningitis in mice.

Methods: We used animal infection and treatment, larvae collection, western blotting, enzyme-linked immunosorbent assay (ELISA), hematoxylin and eosin (H&E) stain, blood-brain barrier (BBB) permeability assays, and an NAD(P)H quinone dehydrogenase 1 (NQO1) enzyme activity, reactive oxygen species (ROS), and superoxide dismutase (SOD) assay kit in this study.

Results: Our findings revealed that larvae recovery, BBB permeability, and inflammatory mediators (interleukin (IL)-1β, IL-6, IL-17A, and tumor necrosis factor (TNF)-α) were increased in A. cantonensis-infected mice. However, p-Nrf2 levels were slightly increased in infected groups. To better understand the modulatory role of Nrf2 in the parasitic meningitis, we also treated A. cantonensis-infected mice with oltipraz (an Nrf2 activator) and trigonelline (an Nrf2 inhibitor). The larvae recovery, BBB permeability, and levels of inflammatory mediators were significantly decreased in the albendazole alone, oltipraz, and albendazole-oltipraz co-treatment groups, particularly in albendazole-oltipraz co-treatment groups. In contrast, trigonelline treatment resulted in increased levels of larvae recovery, BBB permeability, and inflammatory mediators. Moreover, since Nrf2 is involved in the regulation of antioxidant enzymes, we also examined the expression of ROS, NQO1, and SOD. ROS levels were significantly increased in infected groups but decreased in the albendazole alone, oltipraz alone, and albendazole-oltipraz co-treatment groups. NQO1 and SOD levels were significantly decreased in infected groups, but these levels were notably restored during treatment with albendazole alone, oltipraz alone, and albendazole-oltipraz co-treatment.

Conclusions: Our findings revealed the albendazole-Nrf2 activator co-treatment effectively suppressed excessive inflammation compared with the anthelmintics drug (albendazole) treatment alone, and Nrf2 activation might produce a synergistic effect in the inflammatory response of the brain in mice with angiostrongyliasis.

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

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

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

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

Background: Accurate surveillance data are critical for addressing tick and tick-borne pathogen risk to human and animal health. Current surveillance methods for detecting invading or expanding tick species are limited in their ability to scale efficiently to state or national levels. In this study we explored the potential use of scent detection dogs to assist field surveys for a hard tick species: Dermacentor albipictus.

Methods: We used a series of indoor and in situ training simulations to teach scent detection dogs to recognize D. albipictus scent, distinguish tick scent from associated vegetation, and develop a cautious search pattern. After training, we deployed both a scent detection dog survey team and a human-only survey team on transect and surveillance plot surveys then compared the detection rates and efficiency of both methods.

Results: Scent detection dogs required more time and money to train on field surveys but were comparable to traditional tick drags when accounting for cost per unit area surveyed. There was a lack of agreement on positive (ticks present) versus negative (ticks not present) sites between the two methods, implying that neither method is particularly reliable at detecting D. albipictus.

Conclusions: Estimating detection bias and false negative rates for tick surveillance methods such as tick drags will be important for accurately evaluating tick-borne disease risk across space and into the future. We found scent detection dogs to be a reasonable alternative sampling approach to consider when ticks are at low abundance or patchily distributed such as during tick range expansion or novel invasions. Scent detection dogs may also be useful for sampling for ticks in areas or along surfaces that are difficult to sample with the traditional tick drag technique like at ports of entry or livestock competitions.

Background: Hookworms, specifically Ancylostoma caninum and Uncinaria stenocephala, have a clinical impact on the health of dogs, with A. caninum posing a zoonotic risk worldwide. The studies presented here were conducted to evaluate the efficacy of a novel, oral chewable tablet (Credelio Quattro) containing lotilaner, moxidectin, praziquantel, and pyrantel (as pamoate salt) against fourth-stage larvae (L₄), immature adult, and adult A. caninum, as well as adult U. stenocephala, infections in dogs.

Methods: Nine negatively controlled, masked, randomized laboratory studies evaluated the efficacy and non-interference of the drugs against various stages of A. caninum and U. stenocephala. In addition to one pilot study conducted against L₄ A. caninum and one study that assessed efficacy in dogs with naturally acquired U. stenocephala, two experimental studies were conducted against each of the target hookworm species and stages. A total of 16-31 dogs comprised each study. With the exception of the study in dogs with naturally acquired U. stenocephala, dogs were experimentally infected with the target parasite and dosed on Day 0 or 4 with placebo tablets, Credelio Quattro tablets (or components of Credelio Quattro formulation for the pilot study), or individual actives, moxidectin or pyrantel, in the specific studies designed to assess interference. Efficacy was evaluated by comparing the number of worms recovered at necropsy 5-10 days post-treatment between the treated and control groups.

Results: All dogs tolerated Credelio Quattro well. Efficacy of Credelio Quattro was ≥ 99.0% against L₄ A. caninum, ≥ 99.8% against immature adult A. caninum, ≥ 99.9% against adult A. caninum, and ≥ 99.6% against adult U. stenocephala. Additionally, treatment with Credelio Quattro provided a ≥ 99.9% reduction in fecal egg counts 10 days post-treatment.

Conclusions: Credelio Quattro, a novel oral chewable tablet administered at the minimum effective dosages of 20 mg/kg lotilaner, 0.02 mg/kg moxidectin, 5.0 mg/kg praziquantel, and 5.0 mg/kg pyrantel (as pamoate salt), was safe and effective for the treatment and control of L₄, immature adult, and adult stages of A. caninum and adult U. stenocephala in dogs.