Search Results (157)

The mud crab (Scylla paramamosain), an economically important crustacean aquaculture species in southern China, is susceptible to infections due to its immune system lacking acquired immunity. An emergent disease locally termed “pus crab” has caused severe muscle lesions in pond-farmed crabs, but its etiology remained unclear. Here, we applied an integrated approach, histopathology, electron microscopy, metagenomic sequencing, and experimental infection to identify the pathogen of “pus crab”. Histological staining (H&E, Wright–Giemsa, and Masson) revealed muscle fiber dissolution, disordered fiber arrangement, and abundant interstitial spore-like bodies. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) confirmed intracellular spore morphology consistent with microsporidia. Metagenomic profiling showed a pronounced shift in the muscle microbiome, with a marked increase in microsporidian taxa at the genus level and a concurrent decline in bacterial relative abundance. Functional annotation indicated enrichment of pathways related to protein processing, ribosome biogenesis, glycosylation, and the ubiquitin–proteasome system. Isolation of spores from diseased muscle and subsequent injection into healthy crabs reproduced wild-like clinical signs and histopathology, confirming infectivity and implicating microsporidia as the likely etiological agents of “pus crab”. These findings establish a multidisciplinary framework for pathogen identification in aquaculture and provide candidate molecular and biochemical markers for early diagnosis and management. Full article

Microsporidia MB is a natural symbiont of Anopheles arabiensis Patton, 1905 that blocks Plasmodium transmission without compromising mosquito fitness. Developing this symbiont for malaria control requires a thorough understanding of its transmission dynamics across generations under environmentally relevant conditions. This study aimed to evaluate the transgenerational spread of Microsporidia MB in semi-field settings. From field-collected infected females (G0), several independent replicates of Microsporidia MB-infected An. arabiensis were established and maintained under semi-field conditions for six generations (F1–F6). All the mosquitoes were screened for Microsporidia MB prevalence and infection intensity using qPCR after death. Temperature and humidity and wing size were recorded. Two replicates sustained through F6. Microsporidia MB prevalence and intensity increased from F1 to F3–F4 before declining. A weak positive correlation was observed between prevalence and temperature, but not humidity. Female mosquitoes exhibited higher infection intensities. Female wing size varied across generations, while male size remained consistent. This first study on Microsporidia MB transgenerational transmission under semi-field conditions revealed a pattern of initial increase followed by decline in prevalence and intensity. The stability of male size supports the potential use of infected males in release programs. These findings underscore additional investigations into environmental drivers for mosquito symbiont prevalence. Full article

Microsporidia are a group of obligate intracellular parasites with a broad host range. These parasites can cause mild to severe harm to their hosts, making them important targets for research. However, studies on common wild-caught fish from the Atlantic Eastern Central Zone (FAO Area 34) remain scarce. 576 individuals across 35 fish species from this region were collected from local markets between 2011 and 2019. The specimens were dissected, and lesions were examined using histology, wet mounts, PCR, and transmission electron microscopy. However, microsporidian infection was detected only in round sardinella (Sardinella (S.) aurita), with 19 out of 39 individuals infected. Parasitized fish weighed nearly half as much as non-infected ones, indicating a potentially significant economic impact. Molecular and ultrastructural analyses identified the parasite as Glugea (G.) thunni, a species previously reported only from the Mediterranean Sea. This study provides the first record of G. thunni in FAO Area 34, with round sardinella likely serving as its primary host. This and other closely related sequences may represent a single taxonomic entity or, more likely, a complex of a few cryptic species geographically separated across the Mediterranean Sea and the eastern and western North Atlantic regions. Full article

Enterocytozoon bieneusi is the most frequently diagnosed microsporidian parasite in humans and a recognized cause of diarrheal disease, particularly in immunocompromised individuals. Its broad host range, which includes livestock, companion animals, and wildlife, highlights its zoonotic potential and warrants careful epidemiological assessment. This narrative review synthesizes available data on the occurrence and genetic diversity of E. bieneusi in European domestic ungulates (cattle, pigs, sheep, goats, horses, and water buffaloes) and pets (dogs and cats), aiming to provide an integrated perspective on animal reservoirs and their relevance for public health. Publications retrieved from the Web of Science Core Collection database were systematically screened, and country-specific results were extracted, emphasizing prevalence rates, genotype distributions, and zoonotic implications. Across Europe, cattle and pigs emerged as the most studied hosts, frequently harboring zoonotic group 1 genotypes such as I, J, BEB4, BEB6, and EbpA, while small ruminants, horses, and buffaloes remain comparatively undocumented. In pets, the dog-adapted genotype PtEb IX was predominant, but several zoonotic genotypes were also identified. Overall, the current evidence confirms the wide host range of E. bieneusi in Europe but also reveals significant data gaps compared to regions such as China, underlining the need for broader surveillance and harmonized molecular approaches within a One Health framework. Full article

Nosemosis is a disease caused by microsporidia, which are strictly intracellular pathogens, currently considered to be most closely related to fungi. These microscopic parasites infect a variety of hosts, significantly affecting honeybees (Apis mellifera). Nosemosis is one of the most serious diseases of bees and is caused primarily by two species: Nosema apis and Nosema ceranae. This infection adversely affects the digestive tract of the bees, causes a reduction in their vitality, and can lead to the death of entire colonies. The diagnosis of nosemosis has undergone extensive development. Traditionally, the identification of microsporidia was performed by examination of bee digestive tract (macerated) by light microscopy. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) are expensive methods that require skilled personnel and were used only when high resolution was necessary. Modern methods, such as polymerase chain reaction (PCR), allow detection of infection at species and genotype levels, thereby increasing the accuracy of diagnosis. Despite advances in molecular techniques, research into nosemosis still faces challenges. This review focuses on a comparison of different diagnostic techniques and their pitfalls that can be integrated into strategies to combat nosemosis and protect the health of honeybee colonies. Full article

Heating at 95 °C or boiling E. coli HT115 (DE3) cells is often used to extract heterologous dsRNA or kill bacteria, although these temperatures cause dsRNA denaturation and destruction. In this study, we examined the risk of degradation of dsRNA fragments of AT-rich genes at high temperature. The expression of dsRNA fragments of AT-rich genes encoding DNA replication enzymes from the microsporidia Vairimorpha ceranae and Nosema bombycis in E. coli HT115 (DE3) was accompanied by heating the bacteria at 95 °C for 30 min. In contrast to four control fragments with normal GC content, the AT-rich dsRNAs of microsporidia were destroyed by this treatment. The in vitro synthesis and heating of the studied dsRNAs showed the degradation of both microsporidia and control fragments. The thermal degradation of in vitro-synthesized control dsRNA with a normal GC content of 47.6% was prevented by the addition of 2 × YT media, NaCl, or low concentrations of MgSO₄. This demonstrates the important role of mono- and divalent cations in stabilizing heated fragments and helps explain the preservation of their integrity and RNAi-initiating activity despite the treatment of bacteria at temperatures that denature dsRNA. Feeding Colorado potato beetle larvae with the same in vitro-synthesized dsRNA containing fragments of three Leptinotarsa decemlineata genes showed that their thermal destruction was accompanied by a decrease in pest-suppressing activity. No dsRNA degradation was observed at 80 °C or after E. coli sonication, and these treatments, as well as increasing cation content, may help to avoid the degradation of heat-sensitive dsRNA. Full article

The shortage of organs for use in transplantation has contributed to the development of an international commercial market for organ transplantation. Unfortunately, transplant tourism (TT) is associated with risks for surgical complications, poor graft outcome, increased mortality, and infectious complications. TT increases the risk of several viral (HIV and hepatitis B and C viruses), bacterial (Mycobacterium tuberculosis, Pseudomonas sp., Enterococcus sp., Escherichia coli, and Acinetobacter sp.), fungal (Aspergillus sp., Zygomycetes, Ramichloridium sp., Scedosporium apiospermum, and Trichosporon sp.), and parasitic (Plasmodium sp., Trypanosoma cruzi and Strongyloides sp., and Microsporidia sp.) infections. This paper presents a case report of an anonymous patient who travelled to Pakistan and underwent a commercial kidney transplant. He developed infection from extended-spectrum β-lactamase-producing Escherichia coli (ESBL-EC). Moreover, we reviewed all published cases of bacterial, viral, and fungal infections in kidney transplant recipients who bought their organs abroad. Full article

Honey bees are essential pollinators for the ecosystem and food crops. However, their health and survival face threats from both biotic and abiotic stresses. Fungi, microsporidia, and bacteria might significantly contribute to colony losses. Therefore, rapid and sensitive diagnostic tools are crucial for effective disease management. In this study, molecular assays were developed to quickly and efficiently detect the main honey bee pathogens: Nosema ceranae, Aspergillus flavus, Paenibacillus larvae, and Black queen cell virus. In this context, new primer pairs were designed for use in quantitative Real-time PCR (qPCR) reactions. Various protocols for extracting total nucleic acids from bee tissues were tested, indicating a CTAB-based protocol as the most efficient and cost-effective. Furthermore, excluding the head of the bee from the extraction, better results were obtained in terms of quantity and purity of extracted nucleic acids. These assays showed high specificity and sensitivity, detecting up to 250 fg of N. ceranae, 25 fg of P. larvae, and 2.5 pg of A. flavus DNA, and 5 pg of BQCV cDNA, without interference from bee DNA. These qPCR assays allowed pathogen detection within 3 h and at early stages of infection, supporting timely and efficient management interventions. Full article

Microsporidia MB (MB), a promising biological control agent, suppresses Plasmodium falciparum transmission in Anopheles mosquitoes. This study examined the spatial distribution of MB infection in natural populations of An. gambiae s.l. mosquitoes collected in Nigeria and Niger Republic, and its association with insecticide susceptibility in the mosquitoes. Microsporidia MB has wide geographic distribution across Nigeria and Niger Republic. The overall prevalence of MB in F₀ mosquitoes was 12.25% (95% CI: 7.76–16.75%); 25 mosquitoes out of 204 were positive. Geographic variation was observed, with a higher prevalence (5/15 mosquitoes) in Ebonyi State (33.33%, CI: 9.48–57.19%, Fisher’s exact test, p = 0.008). Infection rates were higher in An. coluzzii mosquitoes (21/133 mosquitoes), estimated at 15.79% (CI: 9.59–21.99%) compared to An. gambiae s.s. mosquitoes (4/71), with approximately 5.63% (CI: 0.27–11.00%, χ² = 4.44; df = 1, p = 0.035). Resistant mosquitoes had a significantly higher prevalence of MB infection than susceptible mosquitos at 28.57% (CI: 16.74–40.40%) with an odds ratio of 3.33 (CI: 1.23–9.03, p = 0.017). These findings suggests that MB can be exploited as an alternative for vector control in Nigeria and Niger, but its possible association with pyrethroid resistance suggests that it should be taken into account as a potential confounder when designing insecticide resistance management strategies. Full article

Enterocytozoon bieneusi is one of the most common microsporidian parasites, primarily infecting the intestinal epithelial cells of a broad range of animal species, including humans. To date, no scientific reports have documented Enterocytozoon spp. in animal hosts in Romania. This study aimed to assess the occurrence and genetic characteristics of E. bieneusi in shelter dogs, as well as its potential public health relevance. Between December 2022 and May 2025, a total of 112 freshly voided diarrheal fecal samples were collected from dogs housed in a shelter near Timișoara Municipality, Romania. The samples were subjected to molecular analysis using a two-step nested polymerase chain reaction (PCR) targeting the internal transcribed spacer (ITS) region of the rRNA gene. The resulting sequences were deposited in GenBank^® and analyzed phylogenetically. PCR analysis revealed E. bieneusi DNA in 11 (9.8%) samples, identifying two genotypes, with PtEb IX (n = 10) as the dominant genotype and BEB4 (n = 1), which has zoonotic potential. A significant difference in prevalence was found between juvenile (23.1%) and adult (5.8%) dogs (p = 0.026). Phylogenetic analysis of the ITS sequences showed that the isolates clustered into two distinct clades alongside reference sequences from the GenBank^® database. This is the first report of E. bieneusi infection in animals in Romania, providing essential baseline data and highlighting the need for broader surveillance into its prevalence and genetic diversity in other potential hosts. These results reflect the prevalence and genetic diversity of E. bieneusi exclusively among symptomatic (diarrheic) dogs and should not be generalized to the broader shelter dog population. Full article

One of the common causes of mass death in bee colonies is the infectious disease nosemosis, which is caused by two types of microsporidia, Nosema apis and Nosema ceranae. Of the many factors contributing to the spread of nosemosis, in this paper we consider the hybridization of subspecies of Apis mellifera L. In most of Russia, the native subspecies is the dark forest bee Apis mellifera mellifera, which is representative of the evolutionary lineage M. The export of bee packages and queens from the southern regions of Russia and other countries has led to the fragmentation of the range of these subspecies. First, we determined the maternal and paternal ancestry of 349 honey bee colonies across 12 beekeeping regions of Russia using the mitochondrial tRNAleu-COII locus and nine nuclear SSR markers (Ap243, 4a110, A024, A008, A43, A113, A088, Ap049, and A028). Among them, 140 colonies belonged to subspecies A. m. mellifera, 58 colonies were of hybrid origin, and 151 colonies belonged to evolutionary lineage C. Then, using microscopy and PCR analysis, we performed diagnostics of nosemosis in the studied colonies: N. apis was detected in 87 colonies, N. ceranae in 102 colonies, and coinfection was observed in 36 colonies. The results of our study indicate that the main reservoir of Nosema microsporidia was bees of evolutionary lineage C. Full article

Rodents are recognized as reservoirs of a wide range of pathogens, including microsporidia. The presence of microsporidia in the environment of mainland Spain and its islands has become increasingly known, as the number of studies has multiplied over time. The present study was conducted to determine the occurrence and diversity of microsporidia in three rodent species (Mus musculus, Rattus norvegicus, and Rattus rattus) in the Canary Islands, Spain. Ninety-three fecal samples were obtained from wild rodents on La Gomera and Gran Canaria Islands. Each sample was tested using Weber’s modified trichrome staining and immunofluorescence antibody tests (IFATs) against the Encephalitozoon genus and Enterocytozoon bieneusi. The microscopy-positive samples were subsequently analyzed using a nested polymerase chain reaction (PCR) followed by Sanger sequencing. The staining technique showed 38.7% (36/93) positivity, whereas the IFATs for Encephalitozoon spp. and Ent. bieneusi revealed 3.2% (3/93) and 6.5% (6/93) positivity, respectively. Finally, the nested PCR and nucleotide sequence analysis confirmed a 9.7% (9/93) occurrence of Ent. bieneusi and 17.2% occurrence (16/93) of different undetermined microsporidia species, whereas no Encephalitozoon spp. were detected. Seven different Ent. bieneusi genotypes were detected as follows: three known (AAE1, D, and SBM1) and four novel (GRE1, GRE2, LGE1, and LGE2), all of which belonged to Group 1. The results demonstrate, for the first time, that microsporidia are present in the rodent populations of the Canary Islands. Further studies are needed to determine the impact of the presence of microsporidia in rodents on the zoonotic transmission of these parasites. Full article

Microsporidiosis is a zoonotic disease that derives from disparate sources. Most of the microsporidial agents are host-specific but some are capable of interspecies transmission, causing disease in various animals including humans. Human microsporidiosis may be caused by 17 species, with Encephalitozoon cuniculi, E. intestinalis and E. hellem mostly being responsible for human infections worldwide. Wildlife and migratory waterfowl can serve as reservoirs of these human-infectious agents and play a significant role in disseminating these pathogens into the environment. The aim of the study was to detect E. cuniculi, E. intestinalis and E. hellem in wild, migratory greater white-fronted geese (Anser albifrons) and other Anatidae members in feacal samples obtained in north-western Poland, using a molecular method. We collected 189 fecal droppings from Anatidae species (75 samples from greater white-fronted geese and 114 from other Anser spp.) during autumn migration. New species specific primers for PCR amplification were used to amplify a fragment of the small subunit ribosomal (SSU) rRNA of E. cuniculi, E. intestinalis and E. hellem. All fecal droppings were negative for E. intestinalis and E. hellem whereas E cuniculi was detected in 6 of 189 fecal samples (3.2%; 95% CI: 1.3–6.3%). In total, 1 of 75 tested fecal samples of greater white-fronted geese was positive (1.3%; 95% CI: 0.08–5.7%) while 5 of 114 (4.4%; 95% CI: 1.6–9.1%) tested fecal samples without exact species affiliation (only Anser sp.) were also positive. The phylogenetic analysis placed the sequences obtained from the birds’ droppings in the clade E. cuniculi from various rodents, wild carnivores and humans. Our results provide the first description of the occurrence and genotyping of the microsporidian E. cuniculi in greater white-fronted geese and in other members of the Anserinae Subfamily. Our findings support the results of other authors that E. cuniculi may originate from diverse sources, including common waterfowl. Our results are important in a One Health context, as wild migrating waterfowl may disseminate this zoonotic agent in remote regions through their migratory behaviour. These species should be considered significant sources of zoonotic pathogens, potentially hazardous to domestic and farmed animals as well as humans. Full article

The fall armyworm (Spodoptera frugiperda), a globally invasive pest, poses substantial threats to corn in China. Microsporidia are a group of obligate intracellular parasitic fungi and are considered to have great potential in biological control. In this article, we investigated the pathology of Nosema sp. infection in S. frugiperda larvae at the organismal, cellular, and molecular levels. At the organism level, this microsporidian significantly prolonged the developmental duration of the host, reduced its body weight, caused molting failure, and led to a high mortality rate at 98.9%, 97.8%, and 64.0%, respectively, in 5 × 10⁵, 5 × 10⁴, 5 × 10³ spores/larva doses. Microsporidia infection caused severe damage to midgut cells, including the formation of vacuoles in the cytoplasm, mitochondria, and intercellular spaces, destruction of goblet cells, and partial encapsulation of spores by mitochondria. Transcriptomic profiling revealed significant alterations in gene expression profiles in S. frugiperda larvae following microsporidian infection. The expression levels of genes associated with the chitin synthesis pathway (CHS1, G6PI, GFAT, GNPNA, PAGM, UAP) were inhibited, which may contribute to the effects of Nosema sp. on the growth and development of S. frugiperda. Full article

Ecytonucleospora hepatopenaei (EHP) is a microsporidian pathogen that primarily infects the hepatopancreas of Litopenaeus vannamei. Previous studies on EHP detection primarily focused on histology, in situ hybridization (ISH), and PCR, mainly concentrating on hepatopancreatic infections, with limited research on extra-hepatopancreatic tissues. This study investigates the pathogenic mechanisms of EHP infection in L. vannamei through molecular quantification, histopathology, and proteomics analysis. RT-qPCR was employed to examine the infection differences across various tissues at the molecular level, revealing that the hepatopancreas, stomach, midgut, muscle, gills, and antennal glands are susceptible tissues. Pathological analysis, combining H&E staining, Masson’s trichrome staining, and immunohistochemistry, identified the EHP-targeted sites at the tissue level. Masson’s staining effectively highlighted fibrosis, unveiling the histopathological characteristics of chronic EHP infection, while immunohistochemistry enhanced the specificity of EHP localization. The pathological features of EHP infection were primarily characterized by inflammation, cell degeneration and necrosis, and the accumulation of microsporidia in the cytoplasm. Proteomics analysis was used to interpret the histopathological findings, revealing significant enrichment of pathways related to inflammation, immune regulation, metabolism, and apoptosis regulation. These findings provide new insights into the infection mechanisms and tissue tropism of EHP. Full article