Parasitology International最新文献

Lake Biwa, with its long geological history, has given rise to many endemic species, but only four endemic parasites are known from Lake Biwa and connected water areas. They are considered to have co-evolved with their endemic host species or to have become adapted to the pelagic ecosystem unique to Lake Biwa. The number of parasite species introduced into this water system is rising, facilitated not only by the introduction of new species but also through genetic analyses that have revealed new information about previously known species. In addition, a few species are considered to have become extinct in the lake recently. Parasitological surveys of under-studied host taxa and more genetic studies are essential not only to understand the fauna of the Lake Biwa water system, but also to investigate parasite life cycles and host-parasite coevolution.

Tyzzeria Allen, 1936 is a coccidian genus traditionally associated with Anseriformes, although there are descriptions of Tyzzeria spp. from junglefowls, snakes, skinks and mice. In this sense, the current study performs a taxonomic review of Tyzzeria spp., evaluating those that should be valid, invalid or that require further studies for validation. Along with this review, oocysts morphologically identified as Tyzzeria parvula (Kotlán, 1933) Klimeš, 1963 were recovered from fecal samples of swan geese Anser cygnoid (Linnaeus, 1758) in the mountainous region of the State of Rio de Janeiro, which were molecularly identified through the sequencing of a locus of the small subunit ribosomal RNA (18S) gene, providing the first deposit of the genus Tyzzeria in GenBank. Finally, this sequence of T. parvula prompted a broad phylogenetic analysis covering species of the main chromist taxa, which evidenced homoplasies associated with taxonomic characters of gametogony, basic oocyst configuration and excystation structures; in addition to positioning T. parvula in a monophyletic group within the order Eimeriida together with Schellackia spp., Eimeria spp. and Caryospora-like spp. from reptiles and amphibians.

The present study describes a new myxozoan species, Ellipsomyxa matosi n. sp. infecting the gallbladder of the catfish Ageneiosus ucayalensis, on Jutuba Island, municipality of Belém, state of Pará, Brazil. The new species was diagnosed based on morphological and molecular analyses. 33 specimens were examined between February and May 2023, and all (100 %) presented disporic plasmodia in the bile fluid, with ellipsoidal, slightly elongated mature myxospores, with a subtle valve projection in the apical region and a curved suture line, typical morphological characteristics of the genus Ellipsomixa. The polar capsules were pyriform and of equal size, with a subterminal opening and 6-7 polar tubule coils. No histopathological changes, lesions, or inflammatory responses were observed in the epithelial layer or any part of the tissue. PCA identified the proximity in spore length (SL) of the new species to E. amazonensis and E. papantla. The partial SSU rDNA sequence obtained was distinct from all other available sequences from species of this genus. The phylogenetic analysis obtained high nodal support, grouping the new species as an ancestor of the well-defined clade of Ellipsomyxa species described in the Amazon region.

Dengue is a viral disease present in many regions of the world. Aedes aegypti transmits it, and the most effective way to eliminate the mosquito is during the larval stage. Seaweeds possess metabolites with insecticidal properties, making them potential sources of new larvicides and viable alternatives to synthetic products used to control insect vectors of diseases. Thus, this study aimed to investigate the chemical composition, in vitro toxicity, and larvicidal activities of the ethanolic extract of the seaweed Sargassum vulgare (SE) and hydroalcoholic extract of the seaweed Caulerpa racemosa (CH) against Ae. aegypti. The chemical composition of the crude extracts was evaluated by high-performance liquid chromatography coupled with mass spectrometry (LC-MS), and toxic effects were assessed through in vitro cytotoxicity. The larvicidal activity was evaluated by determining mortality and lethal concentrations (LC₅₀ and LC₉₀), morphological analyses of larvae, and evaluation of the enzymatic action mechanism. The results showed that the extracts contained primary and secondary metabolites, mainly, alkaloids, terpenoids, carbohydrates, fatty acids, and chlorophyll derivatives, all of which were biocompatible at all tested concentrations (3 to 100 μg/mL). The SE and CH extracts showed larvicidal potential at all tested concentrations, achieving 95 % and 50 % mortality after 48 h. Observed changes in the external morphology of the larvae included color change, loss of bristles, and gill filaments. At the same time, the enzymatic action mechanism occurred through stimulation of amylase, trypsin, and acetylcholinesterase activities. Therefore, both seaweed extracts offering alternatives to synthetic chemical insecticides.

Urorchis Ozaki, 1927 and Neoplagioporus Shimazu, 1990 (Digenea: Opecoelidae: Sphaerostomatinae) comprise species parasitic in freshwater fishes of eastern Asia, although the status of these genera is questionable. We revised these genera, primarily using evidence from a molecular phylogeny based on nuclear ribosomal DNA, including new sequences of four known and one new species. Urorchis was part of the clade of Neoplagioporus species, rendering the genus Neoplagioporus paraphyletic. Based on this evidence, we regard Neoplagioporus as a junior synonym of Urorchis, and amend its taxonomic diagnosis. Moreover, we consider Neoplagioporus kajika Urabe & Higa, 2006 to be a junior synonym of Urorchis zacconis (Yamaguti, 1934). Finally, we describe a new species, Urorchis takahaya n. sp., from upstream fat minnow Rhynchocypris oxycephalus collected in an inlet of Lake Biwa, Shiga, Japan.

Background: Ascaris lumbricoides is a nematode that parasitizes the human gastrointestinal tract, and it is the cause of the most common helminthic infections worldwide. It predominates in areas of poor sanitation. Early diagnosis of this intestinal infection is pivotal to avoid its severe and lethal complications such as gut obstruction, volvulus, and perforation.

Case report: A 61-year-old Caucasian female was admitted to the Operational Unit of Gastrointestinal Endoscopic Surgery with abdominal pain, in combination with nausea and vomiting for 2 months. The woman underwent a colonoscopy and surprisingly A. lumbricoides was highlighted. Diagnosis of A. lumbricoides infections is based on the microscopic detection of eggs in stool, thus, patient fecal samples collected were examined by microscopy-based methods, but no eggs were found. Previously, the patient was treated to eradicate H. pylori, using omeprazole, a common proton pump inhibitor.

Discussion: Here, we supposed that previous therapy has mitigated the parasite infection severity. In our patient was identified A. lumbricoides, although she came from a medium socio-economic status family and despite, she reported to have never travelled in tropical and subtropical areas. This report highlights the importance of the awareness of ascariasis and that its preventive measures should be included in all health education programs.

We present the case of a 52-year-old male, with a recent history of travel to Ghana, who was admitted to the ICU due to septic shock caused by severe malaria, with a parasitaemia index of 50 %. He received treatment with intravenous artesunate followed by dihydroartemisinin (40 mg) plus piperaquine (320 mg). Despite presenting with multiorgan failure upon admission, the patient demonstrated significant clinical improvement and a rapid clearance of parasitaemia, with a parasitaemia index of 0 % at 72 h after treatment's initiation. However, he developed severe anaemia with haemoglobin levels as low as 5.6 g/dL, requiring multiple blood transfusions. The patient's anaemia was attributed to post-artesunate haemolytic anaemia (PDAH), based on a history of high parasitaemia levels and the onset of symptoms following artemisinin-based therapy. This conclusion was supported by a positive Coombs' test and elevated haemolytic markers. PDAH is likely caused by the pitting phenomenon, combined with the potential bone marrow suppression or drug-induced, antibody-mediated haemolysis. The patient received oral steroids for their capacity to suppress the immune response driving erythrocyte destruction in PDAH, resulting in a gradual recovery of haemoglobin levels. This case highlights the importance of recognizing PDAH in patients with severe malaria and high parasitaemia. Prompt diagnosis and management of haemolytic complications are crucial for recovery.

Malaria remains a significant health threat in tropical and subtropical regions. The immune response to Plasmodium falciparum involves both humoral and cellular components, including phagocytosis by neutrophils. However, observing phagocytosis through light microscopy is uncommon. This report presents a rare case of falciparum malaria in a Ghanaian twin, highlighting intracellular P. falciparum forms in neutrophils. Two 7-year-old male twins from Ghana were admitted with fever, vomiting, and abdominal pain. They tested positive for P. falciparum infection via rapid diagnostic tests and blood smears. Child 1 displayed significant neutrophilia and intracellular parasites, including trophozoites, merozoites, and a potential schizont, within neutrophils. Child 2 showed no phagocytosis but exhibited other signs of systemic inflammation and hemolysis. Both children were treated successfully with piperaquine tetraphosphate/artenimol (Eurartesim®). This case provides rare microscopic evidence of P. falciparum phagocytosis by neutrophils, suggesting prior antibody development in the patient. While the findings highlight the role of phagocytosis in parasite clearance, the absence of similar observations in the second twin raises questions about individual immune responses and genetic factors. Further research is needed to explore the underlying biological mechanisms.

Black-goggled tanagers Trichothraupis melanops (Vieillot, 1818) are passerine birds commonly observed in the Brazilian Atlantic Forest, Argentina and Paraguay. Tanagers are among the passerines with the highest prevalence and density of coccidian parasites, mainly due to their frugivorous feeding habits that favor fecal-oral transmission. In this context, the current study identifies a new species of Isospora Schneider, 1881 parasitizing black-goggled tanagers captured in the Itatiaia National Park, a protected area with a high degree of vulnerability in Southeastern Brazil. The oocysts of Isospora tiedetopetei Almeida-Berto & Berto n. sp. are subspheroidal to ovoidal, measuring on average 24 by 23 μm. Micropyle is absent. Oocyst residuum absent, but comma-like and splinter-like polar granules are present. Sporocysts are ovoidal to slightly pear-shaped, measuring on average 16 by 11 μm. Stieda and sub-Stieda bodies are present. Sporocyst residuum is present among the vermiform sporozoites, which have striations, refractile body and nucleus. This morphology was different from the other Isospora spp. recorded in the same subfamily as the host. Molecular identification was targeted by the amplification and sequencing of four loci of the mitochondrial genome and the small subunit ribosomal RNA (18S) gene. In molecular and phylogenetic analyses of concatenated sequences of 5 fragments, I. tiedetopetei n. sp. sat in monophyly and/or had high similarities with Isospora spp. from passerines. Finally, based on the morphological and molecular analyses of the oocysts recovered from black-goggled tanagers T. melanops in the current study, I. tiedetopetei n. sp. is established new to science, being the seventh species recorded in the host subfamily Tachyphoninae and the first to have a molecular characterization based on mitochondrial genes and the nuclear 18S gene.

Strongyloides stercoralis (S. stercoralis) is a soil-transmitted nematode that is endemic to tropical and subtropical regions. S. stercoralis has the ability to cause autoinfection, potentially leading to a chronic disease that can last for decades or result in severe hyperinfection especially in individuals who are taking corticosteroids or other immunosuppressive medications. Here, we report the case of a patient presenting a two-week history of symptoms including cough, fatigue, weight loss, pruritus, and rash. Due to a significant increase in the percentage of eosinophils, the patient was referred to the hematology clinic. The patient underwent a comprehensive evaluation that included an autoimmune panel, genetic testing, and imaging methods. The results of these investigations were found to be normal. The upper gastrointestinal system endoscopy revealed eosinophilic duodenitis and corticosteroid treatment was initiated. The commencement of corticosteroid therapy resulted in a worsening of the patient's symptoms. In the repeated endoscopy of the upper gastrointestinal tract, the presence of S. stercoralis larvae was observed between the crypts. Subsequently, stool tests for S. stercoralis diagnosis were also found to be positive. The patient was at risk of developing a hyperinfection syndrome. Corticosteroids are commonly used to reduce inflammation and manage symptoms associated with eosinophilic disorders. The immunosuppressive effects of corticosteroids are known to precipitate S. stercoralis hyperinfection syndrome, which can result in significant morbidity and mortality. This case highlights the importance of maintaining a high index of suspicion for S. stercoralis in patients undergoing immunosuppressive therapy, particularly when presenting with unexplained eosinophilia.