Parasitology最新文献

Theileria parva, a protozoan parasite, is the causative agent of East Coast fever (ECF), an economically important disease of cattle in sub-Saharan Africa. The Muguga cocktail vaccine which comprises 3 T. parva strains, namely Muguga, Kiambu 5 and Serengeti transformed, is used for immunization of cattle to control ECF. However, the relative contributions of these T. parva strains to vaccine efficacy are not fully understood. This study compared the in vitro infectivity of the strains at varying concentrations of 2.75, 84.5, and 169 infected acini/ml using peripheral blood mononuclear cells isolated from a bovine donor. The presence of Schizonts in cytospin smears was used to determine infectivity rates. The results indicated significant differences in the overall infectivity among the 3 strains at the concentrations 2.75 and 84.5 infected acini/mL but not at 169 infected acini/mL (p ≤ 0.05). These results suggest that infectivity potential reduces as the concentration increases. This was also supported by the observation that contamination increased at higher concentrations, complicating visualization and analysis. The findings reinforce the need to support the balanced composition of the Muguga cocktail vaccine to ensure broad-spectrum protection against ECF. This study emphasizes maintaining strain proportions in vaccine formulations. Future research should focus on advanced molecular techniques to refine infectivity assessments and explore strain-specific immune responses in vivo, contributing to optimized vaccine efficacy and sustainable control of ECF in endemic countries.

Through an integrative approach that combined microscopy and molecular analyses of the 18S rDNA gene, this study describes a novel haemococcidian species, Lankesterella nucleoflexa sp. nov., and presents data on another Lankesterella sp. Both parasites were found in the green iguana (Iguana iguana) from Eastern Amazonia, Brazil. Lankesterella nucleoflexa sp. nov. is characterized by a unique nuclear plasticity; its nucleus exhibits variable shapes and condensation states, appearing condensed and seemingly divided when adjacent to the host cell nucleus and elongated when positioned opposite. This species infects erythrocytes, monocytes and heterophils, inducing significant nuclear deformities. Phylogenetic analysis placed both Lankesterella sequences in a clade with other Lankesterella parasites from lizards, highlighting the genetic diversity of this genus within this host group. These findings expand the knowledge about parasitic biodiversity in Neotropical reptiles and underscore the necessity of integrating morphological and molecular methodologies to elucidate the taxonomy of understudied groups such as haemococcidians.

Rattus rattus is a known reservoir of zoonotic pathogens, including Bartonella and Rickettsia, transmitted by ectoparasites such as fleas, mites, lice and ticks. The circulation of Bartonella and Rickettsia in these vectors in Chile remains poorly characterized. To evaluate the association between ectoparasite abundance, prevalence and diversity (including lice, fleas, mites and ticks) and the presence of Bartonella and Rickettsia within ectoparasites collected from R. rattus across different anthropogenic gradients in Chile, a total of 1,339 ectoparasites were collected from 411 R. rattus individuals across 27 localities. Ectoparasites were identified morphologically, and molecular detection of bacteria was performed using conventional and qPCR, targeting multiple genetic markers. Haplotype diversity and phylogenetic relationships were assessed. Bartonella and Rickettsia DNA were detected in fleas, ticks, mites and lice of R. rattus, with prevalence values reported separately for pooled and individually analysed ectoparasites. Bartonella tribocorum, B. rochalimae and B. mastomydis were identified. Rickettsia felis was confirmed in multiple ectoparasite groups. High haplotype diversity was observed in Bartonella but not in Rickettsia. Urbanization and tick prevalence were negatively associated with Bartonella occurrence; flea and tick prevalences were negatively associated with Rickettsia. Rattus rattus and their ectoparasites harbour a diverse range of potentially zoonotic Bartonella and Rickettsia species. These findings highlight the need for integrated surveillance and vector control strategies, especially in areas with variable human-wildlife interaction.

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.