Parasitology Research最新文献

Malaria caused by Plasmodium is responsible for approximately 250 million clinical cases and 600,000 deaths per year, mostly in Africa. Our understanding of Plasmodium parasite biology remains incomplete. The key step of Plasmodium invasion is the blood stage, which is mediated by Erythrocyte binding-like (EBL) and Reticulocyte binding-like (RBL) proteins. Three P. falciparum EBL proteins and their receptors are functional: EBA-175 - Glycophorin A (GPA), EBL-1 - Glycophorin B (GPB), and EBA-140 - Glycophorin C (GPC). Because the fourth EBA-181 ligand recognizes the mysterious erythrocyte receptor Z, which remains unknown, we aimed to characterize its specificity and search for its receptor. The Surface Plasmon Resonance method was employed to evaluate the interaction of the recombinant EBA-181 ligand with sugar moieties and the Rh2b ligand. We have demonstrated that the EBA-181 ligand binds to Neu5Ac and Neu5Gc sialic acids, interacting with the Rh2b protein with a dissociation constant of approximately 3 µM. Moreover, the EBA-181 protein binds to about 100 kDa erythrocyte membrane protein. The P. falciparum EBA-181 merozoite ligand binding was shown to be sialic acid-dependent. It seems that the Rh2b merozoite protein might be the co-ligand cooperating with EBA-181 in erythrocyte invasion. Finally, our studies suggested that erythrocyte Band 3 protein may be a putative receptor for the EBA-181 ligand.

African hematophagous leeches are largely underinvestigated both in terms of their biodiversity and the characterization of the repertoire of bioactive components of their salivary gland secretions. Asiaticobdella (formerly Aliolimnatis) fenestrata Moore, 1939, also referred to as the African medicinal leech, is hence a promising candidate for the identification and functional characterization of putative anticoagulants that may serve as inspirations for the development of new or the enhancement of existing drugs for medical purposes. A. fenestrata inhabits flooded plains of southern African regions and mainly feeds on mammals like black lechwe (Kobus leche Gray, 1850). Whereas several anticoagulants, including two putative hirudins of A. fenestrata, have already been identified in previous investigations, functional characterizations of these components are yet missing. We conducted an in-depth re-analysis of the salivary gland transcriptomic data set of A. fenestrata and identified two additional hirudin-like factors that exhibit a remarkable structural feature-the presence of an RGD motif at or near the N-terminal end of the molecules. The presence of such an RGD motif is a key feature of leech-derived platelet aggregation inhibitors such as ornatins and decorsins. However, both in ornatins and in decorsins, the respective RGD motif is located within the molecule between the 5th and the 6th cysteine residues, but not at or near the N-terminus. We named the two putative platelet aggregation inhibitors "fenestrins." Both the two putative hirudins and the two fenestrins of A. fenestrata were expressed as recombinant proteins, purified, and functionally characterized in either coagulation or platelet aggregation assays.

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.