Parasitology Research最新文献

The infection dynamics of Prochristianella sp., a metacestode parasitizing the Yucatán Peninsula-endemic octopus, Octopus maya, were examined to explore the relationship between host size and parasitic infection parameters. During a red tide event, forty-nine octopuses were sampled from a single locality in the Yucatán Peninsula, México, and classified into three size classes. Infection metrics were assessed, including prevalence, mean intensity, abundance, and total parasite count. The results revealed a significant positive association (r = 0.85) between host size and the number of Prochristianella sp., with larger octopuses exhibiting higher infection parameters. The findings suggest that Prochristianella sp. progressively accumulates in O. maya throughout its very early life, aligning with the general patterns observed in host-parasite interactions. This finding is consistent with previous studies, which suggest that larger hosts may accumulate higher parasite loads due to their prolonged exposure to infective stages and their trophic habits. These results highlight the ecological role of O. maya as an intermediate host in its marine ecosystem, underscoring the potential implications of parasitic infections on its health and population dynamics. This study represents a significant step toward understanding the ecology of parasites exploiting O. maya, providing insights into host-parasite relationships in marine cephalopods and offering a foundation for future research on the health and sustainability of this economically important species.

Gastrointestinal parasitism is a health issue in livestock, particularly in non-intensive farming systems. This research evaluated the prevalence and risk factors associated with gastrointestinal helminths in goats from three ecosystems in Peru: the Andean shrubland (Ancash), dry forest (Lambayeque), and coastal valley (Lima). The study used a cross-sectional design, with random sampling of goats from extensive production systems in each ecosystem. A total of 819 fecal samples were collected and analyzed using qualitative and quantitative parasitological methods. Additionally, coproculture was performed to identify infective larvae of nematodes. The FAMACHA© index was used to assess anemia levels, while body condition scores were recorded to evaluate the nutritional status of the animals. The highest prevalence was recorded in the Andean shrubland (74.2%), followed by the dry forest (63.1%), whereas the coastal valley had the lowest prevalence (59.3%). The most frequently identified helminths were strongyle-type eggs (49.9%) and Skrjabinema sp. (33.7%), while Moniezia sp. (5.4%) and Fasciola hepatica (1.1%) were detected at lower frequencies. The identification of L3 infective larvae of Haemonchus sp., Trichostrongylus sp., Cooperia sp., Strongyloides sp., Oesophagostomum sp., Bunostomum sp., and Teladorsagia sp. highlighted the diversity of gastrointestinal nematodes affecting goats in Peru. Multivariable analysis revealed that anemia (FAMACHA ≥ 3; PR = 1.14), poor body condition (BCS 1-2; PR = 1.03), and age (2-6 teeths or full dentition; PR = 1.12 and 1.08, respectively) were associated with increased infection risk. Males had lower prevalence than females (PR = 0.80), and goats raised in the dry forest and coastal valley had lower risk than those from the Andean shrubland. These findings highlight the influence of physiological status and environmental conditions on parasite burden in goat herds.

Aedes aegypti (Linnaeus 1762) is a significant public health concern in both its native and invaded regions because of the transmission of arboviruses. Target-site mutations in the voltage-gated sodium channel (vgsc) gene, commonly referred to as knockdown resistance (kdr), represent the most extensively studied mechanism underlying pyrethroid resistance. Therefore, we aimed to assess possible pyrethroid and organochlorine resistance levels, knockdown resistance, and mutation types known to contribute to the resistance profile in the Black Sea region of Türkiye in 2020. Bioassay results showed that all field populations, as well as the Bora Bora laboratory strain, were susceptible and predominantly carried wild-type genotypes. For kdr, all samples were wild type for the V410L, L982W, S989P, I1011V/M, L1014F, V1016I/G, and T1520I mutations. The mutant allele was detected in only one specimen in the Pazar population, where it was found in a homozygous state at position F1534C from ten specimens. Novel mutations in the vgsc gene region, with unknown implications for resistance, were determined at positions A1498T, R1599C, P1611L, and P1615S in the studied populations. Two different intron types were detected in the kdr gene (in domain 2) between nucleotide positions 3111 and 3228 and within an intron region (coded as type-1 and type-2). These findings indicate that, Ae. aegypti populations in the Eastern Black Sea region remain susceptible to pyrethroid and organochlorine insecticides. Genetic analyses indicate that these populations likely originated from Asia, with evidence of two distinct lineages. Notably, this study represents the first molecular and phenotypic assessment of insecticide resistance in Ae. aegypti populations conducted in Türkiye.

Neglected tropical diseases (NTDs) remain a major public health concern in sub-Saharan Africa, where inadequate sanitation and unsafe water contribute to ongoing transmission. This study examined the prevalence and associated risk factors of Schistosoma haematobium among school-aged children in 20 WASH-focused communities across four Local Government Areas in Ogun Central, Nigeria, between March 2021 and March 2023. Urine and stool samples were collected from 1019 pupils and analyzed using standard parasitological techniques, while structured questionnaires captured demographic information, WASH indicators, and attitudes toward anthelmintic treatment. The overall prevalence of S. haematobium was 2%. Significant associations were observed between infection and water sources (p < 0.05), toilet facilities (p = 0.045), and hematuria (p < 0.001). Age was also identified as a significant demographic factor influencing infection. These findings highlight the persistent vulnerability of children in WASH-dependent communities to urinary schistosomiasis and emphasize the need for integrated control strategies that combine improved sanitation, safe water supply, health education, and regular mass drug administration.

The major histocompatibility complex (MHC) class II β genes are highly polymorphic and trigger the adaptive immune response in fish against parasitic infections. In channel catfish, exon 2 of the HLA (human leukocyte antigens) and H-2 genes encodes the MHC class II β domain. HLA and H-2 have not been documented in channel catfish populations or associated with parasite infections. We used Ligictaluridus floridanus, a common monogenean ectoparasite, to uncover SNPs in channel catfish. This study uses massive sequencing technology to find single nucleotide polymorphisms (SNPs) in a portion of the MHC class II β domain of the HLA and H-2 genes. Based on an adjusted parasite load, we ranked fish as resistant (RR) or susceptible (SS) to L. floridanus natural infection. We recovered SNPs from 58 fish, 32 classified as RR and 26 as SS. We found 13 SNPs, resulting in 12 non-synonymous changes (4 in HLA and 8 in H-2) and one synonymous change in the H-2 gene. The GG homozygote genotype for the alternative SNP HLA:1849444(C/G), which changes an aspartate (D) to glutamate (E), was significantly associated with susceptibility to L. floridanus. Our study identified 11 haplotypes in the HLA gene, with only one identical to the previously reported allele Icpu-DAB*03 (FKDN). We identified four non-synonymous SNPs in the HLA gene, with a significant association with susceptibility to L. floridanus observed in the genotype GG of SNP HLA:1849444(C/G). In the H-2 gene, the nine SNPs identified were non-significant in any test conducted.

Determining the optimal number of stool samples for accurate parasite detection is crucial in healthcare. However, previous studies have reported conflicting results. This study investigated factors associated with the detection of pathogenic intestinal parasites in additional stool microscopy examinations. This retrospective cross-sectional study at a tertiary care hospital outpatient clinic included patients who submitted three stool samples between 2012 and 2021 and had at least one pathogenic intestinal parasite-positive stool sample. Diagnostic yields for one, two, and three stool specimens were the primary outcome. The secondary outcome was the identification of factors associated with the time to the first positive stool microscopy result, which was analysed using ordinal logistic regression. Among the 103 infected patients, compared with the infection detection rate in the first specimen, the rate increased with the second specimen and further increased with the third specimen, achieving a cumulative detection rate of 100%. Some parasites, such as hookworms, were easily detected in the first sample. However, more than half the patients infected with Trichuris trichiura and all patients infected with Isospora belli were missed if only one stool specimen was collected. Immunocompetent hosts were significantly more likely to have pathogenic intestinal parasites detected in later stool specimens (adjusted ordinal odds ratio = 3.94 [95% confidence interval: 1.34-14.05]). Collecting multiple stool specimens was associated with a higher likelihood of detecting pathogenic intestinal parasites, particularly in immunocompetent patients. Clinicians may request a second or even a third sample if the first is negative.

Helminthic parasites cause chronic infections due to their ability to generate immune regulatory networks in their hosts; however, an additional component in this interplay is the microbiota. In this regard, new insights have emerged from intestinal helminthic infections, but whether extraintestinal worms are able to alter intestinal microbiota is unknown. Here, we explored microbiota changes occurring during experimental infection with the peritoneal, non-migrating cestode Taenia crassiceps. Our sequencing approach allowed for the identification of 56 families and 119 genera in the fecal samples. We compared the microbiota composition between wild-type (WT) and NLRP3-deficient mice (NLRP3^-/-), since we recently reported that the lack of NLRP3 dramatically enhanced mouse resistance against T. crassiceps. Prior to T. crassiceps infection, NLRP3^-/- mice harbored distinct microbial communities when compared to WT animals. The lack of NLRP3 resulted in enrichment of Akkermansia and Lachnospira, while reducing Clostridium, Dubosiella, and Bifidobacterium. Strikingly, Lactobacillus presented a comparable abundance in uninfected WT and NLRP3^-/- mice. Upon infection, a progressive increase in Akkermansia and a transitory expansion of Lachnospiraceae were observed in WT mice but not in NLRP3^-/- mice. A remarkable finding was that T. crassiceps infection inhibited Dubosiella, whereas the groups with enhanced resistance to T. crassiceps (NLRP3^-/- mice and WT individuals co-housed with NLRP3^-/- mice) presented a greater abundance of Dubosiella, indicating that resistance against T. crassiceps might be coordinated by this bacterium. Our study reveals that intestinal microbiota can also be modulated through a peritoneal-gut axis, in which the players (antigens and immune cells) remain to be identified. In addition to resistance, microbiota changes could be involved in the T. crassiceps-evoked anti-inflammatory and anti-oncogenic effects.

The screwworm fly, Cochliomyia hominivorax, is a significant pest in Brazil, posing threats to agriculture and public health. Laboratory rearing is crucial for developing control strategies like the sterile insect technique (SIT); but the effects of multi-generational rearing on the fly's biological parameters are not fully understood. This study investigated the impact of rearing C. hominivorax for 12 inbred generations on its morphometrics, reproductive capacity, and life expectancy. Specimens were collected at distinct developmental stages across 12 generations for morphometric analysis, and key viability traits were assessed through biological assays. Data were analyzed using linear mixed-effects models and Kaplan-Meier survival analysis. The results revealed that morphometric parameters and key reproductive traits (oviposition, egg weight, hatchability, and larval survival) remained stable across all generations (p > 0.05). However, a significant decline in adult life expectancy was observed (log-rank test, χ² = 338.257, p < 0.001), becoming pronounced from the fifth generation onwards. Significant sexual dimorphism was also confirmed: males were larger and heavier (Mann-Whitney U = 9884.5, p < 0.001), while females exhibited significantly greater longevity (log-rank test, χ² = 44.538, p < 0.001). Continuous laboratory rearing of C. hominivorax appears robust for maintaining physical and reproductive traits, but negatively impacts fitness-related traits like longevity, likely due to inbreeding. These findings provide a critical quantitative baseline for quality control in mass-rearing programs and highlight the need for strategies to manage genetic diversity in laboratory colonies to ensure their effectiveness for research and SIT applications.

Ectoparasitic infections pose significant challenges in aquaculture, often leading to high fish morbidity and mortality. Macrogyrodactylus congolensis, a viviparous monogenean parasite infecting Clarias gariepinus, is of particular concern due to its rapid reproduction and transmission rates. This study investigates the effects of ionic silver (AgNO₃) and engineered nano-silver (nAg) on the reproductive dynamics and spatial distribution of M. congolensis, both on and off its host. Parasite reproduction off the host was assessed under unexposed then varying concentrations of AgNO₃ (0.1-100 µg/L) and nAg (0.1-100 mg/L), while host-parasite interactions were conducted using the LC₁₀ of the parasite for AgNO₃ and nAg. Results indicate that silver-based treatments exhibit concentration-dependent inhibitory effects on parasite reproduction. At lower concentrations (≤ 2 µg/L AgNO₃ and ≤ 1 mg/L nAg), minimal effects were observed. In contrast, higher concentrations (≥ 50 µg/L AgNO₃ and ≥ 20 mg/L nAg) significantly suppressed reproduction. Parasite mortality increased with silver exposure, particularly in off-host conditions. Spatial distribution heatmaps illustrated that M. congolensis primarily occupied the host's head region, i.e. preference for microhabitats that support survival and transmission. Additionally, scanning electron microscopy (SEM) analysis of parasites exposed to both forms of Ag showed tegument disruption. The host integument showed minimal punctures when exposed to AgNO₃ and no damage in the control and exposure to nAg. While AgNO₃ and nAg show potential as antiparasitic agents in aquaculture, their broader ecological and physiological impacts on host fish and the environment require further investigation. The study highlights the need for optimised dosing strategies to balance efficacy and environmental and host safety, offering valuable insights into developing alternative parasite management approaches for aquaculture.

Toxoplasma gondii is an intracellular protozoan with worldwide distribution and is of significant importance for One Health due to its zoonotic potential. Although its presence in terrestrial environments is well documented, little is known about its circulation and genetic diversity in the marine ecosystem. This study investigated the occurrence of T. gondii in seabirds rescued from the southern coast of Brazil, focusing on bioassay and molecular characterization. Tissue samples (the heart, brain, liver, lung, and pectoral muscle) from 76 seabirds were received. Of these, 26 were from Larus dominicanus, one Macronectes giganteus, one Pachyptila vittata, five Phalacrocorax brasilianus, two Procellaria aequinoctialis, two Puffinus puffinus, 35 Spheniscus magellanicus, two Sterna hirundo, and two Sula leucogaster. The samples of each bird were processed in pool for peptic digestion. The product of each digestion was inoculated (1 mL/SC) into three mice per bioassay/bird. DNA was extracted for molecular characterization using the PCR-RFLP technique with markers SAG1, 5'-SAG2, 3'-SAG2, Alt. SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and Apico. Brain cysts were detected in 16 bioassays. The ToxoDB #170 genotype was identified as an isolate of kelp gull (Larus dominicanus) while another bioassay from the same species did not match the database, suggesting a previously undescribed genotype. Infection occurred through ingestion of sporulated oocysts present in the environment or in fish, bivalves, and crustaceans, which have demonstrated parasitic bioaccumulation. This work highlights the dispersal and infection capacity of different classes of T. gondii hosts and the role of birds as environmental sentinels for marine contamination.