Parasitology Research最新文献

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.

Trichinellosis is a meat-borne zoonosis of ubiquitous distribution. The severity is variable, and fatalities may occur. Immune-mediated inflammation plays an important role in the pathogenesis of the disease. Thus, safe and effective compounds with anti-inflammatory properties are needed. Our study was designed to evaluate the effects of fluvoxamine as an adjuvant to albendazole during the intestinal and migratory phases of trichinellosis. Therefore, Trichinella spiralis-infected mice were treated with either fluvoxamine, albendazole, or a combination of both drugs. Notably, the parasite burden was reduced in the intestines and muscles of fluvoxamine-treated mice compared to the infected control, denoting a detrimental effect of the drug against Trichinella spiralis. Moreover, in comparison with the infected control, there was a marked improvement in intestinal and muscle inflammation with the treatment, evidenced by the reduction in COX-2 and TNF-α and the decrement of inflammatory infiltrates in tissues. The expression of iNOS was also reduced in the muscles. Treatment with fluvoxamine alleviated the oxidative stress in the intestines and muscles with a reduction in malondialdehyde and H₂O₂ and an increase in reduced glutathione levels. Finally, fluvoxamine moderated the immune response, as evidenced by the downregulation of the levels of IL-4 and IFN-γ and the increase of those of IL-10 in tissues. Characteristically, all these beneficial effects were maximal in mice receiving the combined treatment. In conclusion, fluvoxamine administration during the early phase of trichinellosis exhibited immunomodulatory and anti-inflammatory activities that potentiated the efficacy of albendazole. Therefore, fluvoxamine could be considered a useful adjuvant treatment in trichinellosis.

Gastrointestinal parasites have been reported in wild Sunda pangolins (Manis javanica), but the clinical significance of such detections is often unknown. This report describes pathological lesions in the stomachs of two dead wild Sunda pangolins caused by Gendrespirura sp.. Gross and histopathological examination showed gastritis and hyperkeratosis in infected animals. Morphological identification confirmed the presence of Gendrespirura sp., and molecular analysis revealed a close phylogenetic relationship with the genus Gendrespirura, supporting placement within the family Habronematidae. This report highlights the pathological significance of parasite infections in wild pangolins in Singapore, further advancing our understanding of the natural biology and parasitology of wild Sunda pangolins, and the effects of these infections on the health and conservation of this critically endangered species.

Anisakid nematodes are widespread marine parasites with complex life cycles involving invertebrates and fish as intermediate or transport hosts, and marine mammals as definitive hosts. Despite their ecological importance, and the zoonotic potential associated with the larval stages found in fish, recent data on anisakid species diversity in pinnipeds from Norwegian waters remain scarce. In this study, we investigated anisakid infections in two juvenile harbour seals (Phoca vitulina) stranded along the southern coast of Norway. Gastrointestinal nematodes were collected, morphologically classified to the genus level, and subsequently identified to species level through molecular analyses of mitochondrial (mtDNA cox2) and nuclear (rDNA ITS) markers.Five anisakid species were identified: Contracaecum osculatum sp. A (reported here for the first time in harbour seals), C. osculatum (sensu stricto), Phocanema decipiens (s.s.), P. krabbei, and Anisakis simplex (s.s.). The latter species was found in unexpectedly high abundance and in fully developed adult stages in one of the seals. Notably, these adult A. simplex (s.s.) exhibited large body size, in contrast with previous studies reporting either absence or minimal presence of adults in harbour seals. The underlying mechanisms promoting growth and reproductive development of A. simplex (s.s.) in this host species remain unclear, but may involve a combination of host-specific physiological traits, environmental factors, and parasite phenotypic plasticity. Gross pathological examination revealed multiple gastric and intestinal ulcers in the same seal, including seven crateriform lesions consistent with ulcerative gastritis and enteritis, associated with nematode attachment and feeding. These findings expand the current knowledge on anisakid diversity in P. vitulina and provide novel evidence of its role as a definitive host for A. simplex (s.s.) in Norwegian coastal waters. Furthermore, the results suggest that competitive interactions among anisakid species, combined with ecological and physiological host factors, may facilitate the development and maturation of A. simplex (s.s.) in harbour seals. Further studies are warranted to assess the frequency and health implications of such infections in wild pinniped populations.