Parasitology最新文献

The heligmosomid nematodes Heligmosomum mixtum and Heligmosomoides glareoli are dominant helminths infecting bank voles (Clethrionomys glareolus) in the temperate forests of NE Poland. Both are relatively long-lived species that accumulate in hosts with increasing host age. Based on studies showing that the closely related species, Heligmosomoides bakeri is immunomodulatory in murine hosts, we hypothesized that heligmosomid-infected bank voles should show higher prevalence and abundance with other helminths. To test this hypothesis, we analysed a database containing quantitative data on helminth parasites of bank voles (n = 922), comprising worm burdens recorded during 4 surveys, conducted at 3- to 4-year intervals, in 3 forest sites, during late summer of each year. After controlling for both intrinsic and extrinsic factors, the presence of heligmosomid nematodes was significantly associated with higher species richness of other helminth species, with the greater likelihood of voles carrying other helminth species, with higher worm burdens of other helminths and with significant positive covariance of heligmosomid burdens with those of other concurrently residing helminths. These patterns might be explained by a number of biological processes, including correlated host exposure or correlated host susceptibility not driven by the parasitic infections themselves. However, we consider it most likely that these results are consistent with the idea that like H. bakeri, the heligmosomid nematodes of bank voles employ non-specific immunomodulation to facilitate their own long-term survival, with the consequence that other concurrently infecting intestinal helminths benefit.

Research on helminth parasites of amphibians and reptiles has a long-standing history and has seen continuous growth. Recent efforts by various authors to compile comprehensive checklists are crucial for advancing our understanding of parasite diversity, ecology and evolution. Nematodes belonging to the family Molineidae parasitize vertebrates worldwide, with the genera Kentropyxia, Oswaldocruzia, Poekilostrongylus, Schulzia and Typhlopsia identified as infecting amphibians and reptiles across the Neotropical and Panamanian regions. While these parasites are relatively common, there is a lack of updated identification keys and incomplete information about their morphology, biology, distribution and host range. In this paper, we conducted an extensive bibliographic survey of Molineidae nematodes in amphibians and reptiles and provide a checklist of 53 species found in the Neotropical and Panamanian regions, including the Caribbean islands, along with updated details on their diversity, host range and geographic distribution.

Although venomous snakes from the family Viperidae, such as Bothrops atrox, are recognized for their medical importance due to snakebite accidents, few studies on parasitological aspects have been carried out with them, especially in the Amazonia region. Using morphological and molecular tools, we described a novel haemogregarine species infecting the common lancehead snake B. atrox from Eastern Amazonia, Brazil. Hepatozoon atrocis sp. nov. has mature gamonts that are morphologically distinct from those reported in the literature, which are often compact, with dispersed or encapsulated cytoplasm and chromatin. In the phylogeny recovered from the 18S rRNA gene, the Hepatozoon atrocis sp. nov. sequences formed a new clade, comprising a sister group to Hepatozoon spp. detected in other snakes, anurans, lizards and marsupials. This study reports the first Hepatozoon species described in the common lancehead snake. In addition, it provides a robust review of haemogregarine species infecting viperids from all over the world.

Female genital schistosomiasis (FGS) remains a neglected sexual and reproductive health (SRH) condition, predominantly affecting women and girls in sub-Saharan Africa. Infection with Schistosoma haematobium, resulting in trapped parasite eggs in the genital tract, causes lesions that mimic sexually transmitted infections and cervical neoplasia, often leading to misdiagnosis, stigma and delayed treatment. This review summarises current developments on FGS burden, prevention, diagnostics, integration, policy, community engagement and identifies critical threats to progress. Ongoing surveys show promise in ensuring robust burden estimates and age-related risk data. Diagnostic advances include portable colposcopy, digital image analysis techniques and molecular assays, although limitations persist in resource-limited settings. Praziquantel remains the cornerstone of treatment, yet single-dose regimens inadequately reverse established lesions; repeated dosing shows improved parasite clearance but limited lesion regression, highlighting the necessity for early, life-course preventive chemotherapy including access to paediatric praziquantel. Successful programmatic pilots have developed training curricula, minimum service packages, community engagement tools and have integrated FGS care into SRH platforms. Policy momentum is building through World Health Organization taskforces and national strategies, yet sustainable financing remains a challenge. Key threats include bilateral aid reductions, climate change, emerging infections, rising healthcare costs and persistent gender inequities. To address these challenges, we propose seven priority actions, encompassing all health system building blocks, for the global community. Nationally coordinated, multisectoral efforts are urgently required to embed FGS prevention, diagnosis and management within broader health systems, thereby improving outcomes for affected women and girls.

Archaeological sediments can be used to retrieve evidence for parasites that infected past populations, giving evidence for disease, diet, sanitation, and migration in the past. To increase our understanding of parasite infections in Roman Britain and determine which parasites may have infected people living at Vindolanda, sediment samples were collected from a drain connected to a latrine at the bath complex of Vindolanda. These samples were used to look for preserved parasite eggs and cysts deposited in the drain with the faeces of people who used the latrine. Microscopic analysis was used to identify eggs of helminths, and enzyme-linked immunosorbent assay (ELISA) was used to look for protozoan parasites that can cause severe diarrhoea. Eggs of Ascaris sp. (roundworm) and Trichuris sp. (whipworm) were found by microscopy and Giardia duodenalis was detected using ELISA. All of these parasites are transmitted by the faecal-oral route, usually through contaminated food and water. This is the first evidence for G. duodenalis in Roman Britain. A range of zoonotic and faecal-oral parasites have been found at other sites in Roman Britain, yet the drain studied from Vindolanda only contained faecal-oral parasites that can be transmitted directly between humans. This predominance of faecal-oral parasites is similar to a pattern found in large urban sites in the Roman Mediterranean and other military sites in the empire. In contrast, sites from larger urban cities in Roman Britain, such as London and York, appear to have a more diverse range of parasites.

Dioecious species that reproduce by internal fertilization typically carry an associated risk of exposure to sexually transmitted parasites and pathogens. When hosts intermingle for procreation, certain protist and helminth parasites, for example, transfer successfully between individuals and then navigate across various life history traits of their hosts, often probing dimensions in both sex and gender, respectively. In humans, there are many sexually transmitted infections as well as sexually transmitted diseases. A well-known sexually transmitted infection is the flagellated protist Trichomonas vaginalis that causes trichomoniasis, with over 150 million new cases reported annually. By contrast, the schistosome blood fluke Schistosoma haematobium, though not a sexually transmitted infection, causes significant damage to the male and female genital tracts. Such overt damage raises risks of spreading and acquiring Human Immunodeficiency Virus and Human Papilloma Virus. In Africa, over 50 million women continue to suffer from female genital schistosomiasis, alongside a poorly quantified global burden of travel-related infections. In conjunction with male genital schistosomiasis, urogenital schistosomiasis causes much suffering, within and between afflicted households, inclusive of stigmatization. Both trichomoniasis and schistosomiasis expose several public health needs currently addressed inadequately by routine sexual and reproductive health services. This preface to the Parasitology Special Issue entitled 'Parasites of the genital tract: short- and long-term consequences', introduces 19 papers that explore the short - and long-term impacts of parasitic infections within the genital tract. While current parasitological research is weighted towards human medicine, we encourage future studies that explore veterinary contexts and analogous parasitic diseases within wildlife.

The genus Apharyngostrigea comprises a group of diplostomoidean digeneans that parasitize birds of the family Ardeidae (herons), with approximately 20 species described worldwide. Despite numerous efforts, a robust phylogenetic framework to delimit species within the genus is still lacking, mainly due to the limited morphological variation among its members. This study employed an integrative taxonomic approach, combining nuclear and mitochondrial DNA sequences with morphological data to assess species boundaries within Apharyngostrigea based on specimens collected from southeastern Mexico. Using a combination of species discovery (Automatic Barcode Gap Discovery, Assemble Species by Automatic Partition, General Mixed Yule Coalescent and Poisson Tree Processes) and validation methods based on Bayesian gene tree topologies (BPP and PHRAPL). We found high diversity within this genus in southeastern Mexico. Our analyses supported the delimitation of four nominal species that were previously described and validated in this study, along with the redescription of three of them. In addition, through species delimitation methods and morphological examination, we identified two candidate species and/or lineages that require further evidence to be formally described. This study demonstrates that an integrative taxonomic approach provides a robust framework for species delimitation in taxonomically complex groups such as Apharyngostrigea.

Loiasis is widespread in Central Africa. Some acute symptoms are associated with high Loa loa microfilaraemia, but the relation between the latter and the adult worm burden infecting an individual with loiasis is still unclear. This study aims to determine whether polyinfection by several reproductive female worms could be assessed using genetic variation in the mitochondrial genome of microfilariae. Microfilariae were collected from the individuals' blood. An optimization of the DNA extraction method that provides enough genetic material and minimization of human host contamination was the first step of the study. Extracted DNA was sequenced using the Illumina platform. Genetic variation in the mitochondrial genome was assessed by identifying polymorphic Single Nucleotide Polymorphisms (SNPs) and estimating the number of haplotypes. Dedicated DNA extraction kits yielded more DNA extracted (mean: 530 ng; SD = 211) from dried blood smears than the in-house chloroform-isoamyl method (mean: 102.5 ng; SD = 118). Filtering the slide elution and venous blood with 5 µm pore size microfilters improved parasite DNA mapping rates (54.64-79.65%). Analysis of polymorphism in the microfilariae mitochondrial genome from three individuals revealed 50, 207 and 332 polymorphic SNPs, respectively. A total of 7 to 20 mitochondrial DNA haplotypes were identified, representing the minimum number of fertile female worms. This study presents the first approach to estimating the L. loa female worm burden and highlights female parent polyinfection in individuals with loiasis.

Paraxerus cepapi is an arboreal tree squirrel that occurs in the Savanna biome of Africa, and information on its parasite diversity is limited and mostly qualitative. The aim of the study was to record the diversity and abundance of ecto- and helminth parasites associated with P. cepapi across its distribution in South Africa. P. cepapi individuals (n = 94) were opportunistically obtained from eight localities during 2020 to 2024. In total, 21 parasite species (19 ectoparasites and two nematodes) and one tick species group were identified. This included lice, ticks, fleas, a mesostigmatic mite, chiggers, nematodes and cestodes. Nematodes were the most prevalent (93·67%), followed by lice (80·85%). Syphatineria cepapi was recorded in 92·41% of P. cepapi, while an unknown Strongyloides species, resembling S. robustus, was recorded in 21·52% of squirrels. The lice species displayed variation in parasitope preference, while chiggers were primarily recorded in the ears. This study provides new country records for the lice species Werneckia paraxeri and Enderleinellus heliosciuri, for the chigger species Microtrombicula polymorpha, and for the nematode S. cf. robustus. New locality records were documented for the nematode S. cepapi in South Africa, and P. cepapi is a new host record for the eight chigger species and S. cf. robustus. It is evident that P. cepapi in South Africa hosts a considerably larger diversity of parasite taxa than previously recorded. Nematode counts were related to host length. These findings warrant future studies on the parasite diversity of P. cepapi in Africa.