Historical accounts suggest that malaria was endemic in ancient southern Anatolia, possibly as early as 800 BCE, but overwhelmingly from classical antiquity onwards. However, measuring the level and extent of malaria risk for premodern periods remains difficult, given the lack of quantifiable data. Surviving records indicate a particularly high prevalence of malaria-like symptoms in lowlands of Cilicia Pedias (southeastern Anatolia, modern Türkiye), especially with travellers for whom the region was a vital transit zone between Anatolia and Mesopotamia or the Levant. A geographic information system (GIS)-based multilayer malaria risk model developed for application to antiquity highlights the insalubrious nature of the region. For references to apparent malarial infection with spatial specificity, it provides quantified confirmation of malaria risk in the indicated locations. Combined with a new method for mapping ancient road paths, the model assigns risk figures to travel along those routes by merchants, pilgrims and armies throughout antiquity. Model-produced maps depict risk for Cilicia Pedias and its major roads. Modelled risk data correlate extremely well with historical accounts of malaria-like illness related to victims’ known itineraries from the 4th century BCE through the 12th century CE. These results support interpretation of reported sicknesses as malarial infection, and highlight the peril of the disease for immune-naïve travellers through the region; and, indeed, the impact of Plasmodium parasites on outcomes of certain historical events. This replicable model provides a case-study for combining GIS and text-based methodologies in evaluating malaria’s impact in the premodern Mediterranean, and application of similar techniques in other regions.

Clinical toxoplasmosis is a rare but often fatal disease that impacts several medical fields, including obstetrics, ophthalmology, transplantation, oncology and the context of the AIDS pandemic. The prognosis for patients with toxoplasmosis largely depends on timely treatment, which makes early diagnosis a priority for clinicians. However, diagnosing toxoplasmosis is a significant challenge due to the lack of specific clinical symptoms. This issue is further complicated by the high seroprevalence of Toxoplasma in the general population, which is far higher than the incidence of the disease. There are currently no clinically useful predictors for toxoplasmosis. Epidemiological studies and host–parasite interactions suggest that the incidence of toxoplasmosis depends on a combination of host and parasite factors. Significant risk factors include immunodeficiency, in utero exposure, genetic predisposition, anti-Toxoplasma antibody levels, older age, virulence of the strain, parasite burden and the infectious form of the parasite. Understanding these risk factors is important for clarifying the uncertainties regarding the incidence of toxoplasmosis and improving patient outcomes. In this review, we discuss the significance of these factors and current measurements for parasite-related factors. Additionally, we discuss potential preventive strategies that focus on screening as well as control of modifiable risk factors.

The northern hookworm, Uncinaria stenocephala, is the primary hookworm infecting dogs in temperate regions, but red foxes (Vulpes vulpes) are also frequent hosts. The extent to which fox-derived U. stenocephala contributes to canine transmission remains unclear. In this study, we assembled complete mitochondrial genomes (mitogenomes) from two adult U. stenocephala worms collected from red fox and two mitogenomes recovered via genome skimming from dog faecal egg isolates. Comparative analysis revealed >99% identity across all U. stenocephala mitogenomes with no discernible genetic differences for dog- and fox-derived U. stenocephala, supporting their conspecificity. Phylogenetic analysis confirmed paraphyly of the genus Uncinaria and clear distinction of U. stenocephala from the badger hookworm U. criniformis, resolving historical taxonomic ambiguity. We applied a 3% nucleotide divergence threshold to assess species boundaries across hookworm mitogenomes, confirming potential cryptic diversity in Necator americanus, U. sanguinis and A. caninum. Our findings demonstrate the utility of genome skimming for recovering hookworm mitogenomes from faecal samples and highlight the need for broader mitogenomic characterization across hookworm taxa to refine taxonomy and understand host associations.

The probability that a disease will manifest is highly variable. Susceptibility to disease is influenced by genetic background, environment and lifestyle choices. In this review, we put forward the premise that evolution of disease susceptibility may be partially influenced by the interaction of divergent pathogen DNA-binding proteins with variable binding sites in the host genome. The hypothesis put forward is derived from recent data obtained from work on the protozoan parasite, Theileria annulata, together with related evidence from viral and bacterial pathogens that have been postulated to modulate host epigenome architecture. The pathogen proteins highlighted have the potential to mimic functions of mammalian epigenome organisers linked to a range of disease syndromes. It is feasible, therefore, that the evolutionary relationship between pathogen and host impacts susceptibility to a range of conditions, such as autoimmune disorders and cancer, which are not directly linked to pathogen infection.

Toxoplasma gondii (T. gondii) is a neurotropic parasite that establishes latent infection in the central nervous system (CNS), and may alter behaviour and contribute to neuronal dysfunction. However, its impact on cognitive performance and CNS pathophysiological alterations in people with HIV (PWH) remains unclear. A cross-sectional study of adult PWH was conducted, assessing latent T. gondii infection through serum IgG levels in the absence of neurotoxoplasmosis. Neurocognitive impairments were assessed through neurocognitive testing across 6 domains, along with depressive and anxiety symptoms evaluation, and educational attainment. CNS pathophysiological alterations were assessed through amyloid-β1-42, total tau, phosphorylated tau, neopterin, and S-100β quantification in cerebrospinal fluid (CSF). Fifty-eight PWH were included, and T. gondii seropositivity was detected in 46.5% of participants (27/58). Overall, cognitive performance was largely comparable between groups, although subtle, non-significant declines were observed across several domains. T. gondii-seropositive individuals demonstrated a faster completion of Trail Making Test Part B (β = −35.79 sec; 95% CI: −67.78 to −3.86), lower educational attainment (β = −1.92 years; 95% CI: −3.76 to −0.09), without different levels of CSF biomarkers for neuronal-synaptic degeneration, Alzheimer’s pathology, beta-amyloid deposition, macrophage-derived inflammation and glial activation-degeneration. In PWH with low CD4 counts, latent T. gondii infection was not associated with overt cognitive impairment or detectable CNS pathophysiological alterations. Instead, an atypical profile emerged, combining faster task-switching with lower educational attainment and subtle, non-significant declines in other domains. These findings highlight the complex nature of T. gondii–host interactions and need for longitudinal studies to clarify long-term neurocognitive outcomes.

Ascaridia galli and Heterakis gallinarum, the most prevalent nematodes of chickens, inhabit the small intestine and caeca, respectively, and often co-occur. Current excreta egg count (EEC) methods do not differentiate between their eggs, and although chickens produce two distinct excreta types – intestinal excreta (IE) and caecal excreta (CE) – the distribution of eggs of these species across them remains poorly understood. Forty Hy-Line Brown laying hens (40 weeks, mean body weight (BW) 2·07 ± 0·02 kg), cleared of prior nematode infection and artificially infected with A. galli (n = 20) or H. gallinarum (n = 20) were housed in separate floor pens and monitored for 26 weeks. Assessments included clinical signs, EECs from IE, CE and mixed excreta (ME), and worm recovery from subsets of birds at 8, 14, 20 and 26 weeks. Neither infection resulted in clinical signs, but A. galli slightly reduced BW gain (0·5 g/week/hen) than H. gallinarum (2·8 g/week/hen). Egg detection aligned with worm predilection sites: A. galli eggs were predominantly found in IE, while H. gallinarum eggs were largely confined to CE. In ME samples, egg counts were reduced by 45% relative to IE for A. galli and 60% relative to CE for H. gallinarum. EECs showed a negative but non-significant association with excreta moisture content. Natural re-infection produced a stable adult worm population in both infections. These findings demonstrate that analysing IE and CE separately provides a practical, non-lethal approach for differentiating these infections, while ME appears to have limited diagnostic utility. Further studies should evaluate these patterns across broader conditions and individual variation.

Leishmaniasis is a neglected parasitic disease responsible for significant morbidity and mortality. Currently, there is no vaccine approved for clinical use. Therefore, controlling infections in infected individuals depends on interventions to prevent infected female sand flies from biting humans, treatment of clinical infections or alternative treatment methods. This review focuses on the types of vaccine developed to control leishmaniasis and which vaccines have made it through to clinical trials. It also discusses the role CRISPR technology may play in improving vaccine candidates design.

Biomphalaria straminea (Gastropoda: Planorbidae) and Physa acuta (Gastropoda: Physidae), both invasive species in southern China, are important vectors for zoonotic diseases. However, the lack of information on the infection dynamics of Angiostrongylus cantonensis in these snails leaves gaps in understanding the compatibility mechanisms between the snails and the parasite. This study aims to reveal differences in A. cantonensis infection between B. straminea and P. acuta from Guangdong, southern China, and to investigate the potential interaction mechanisms between A. cantonensis and P. acuta. We found that both phenotypic color variants of B. straminea snails were highly susceptible to A. cantonensis (100%). The load of the L3 larvae ranged from 243 to 765 per snail, and it was positively correlated with the infection dosage. Based on the comparison of third-stage larvae quantities, B. straminea is more suitable than P. acuta for establishing the life cycle of A. cantonensis in the laboratory. In contrast, geographic isolates of P. acuta exhibited variable susceptibility (13–91%) and markedly lower parasite loads, with 6–32 third-stage larvae per snail. Diverse strains of P. acuta exhibit distinct immune responses to A. cantonensis, characterized by varied expression patterns of immune-related genes such as TEP1, HSP70, FREP2, Cu-Zn_SOD1, Fe-Mn_SOD2, MIF and Galectin. Our findings establish B. straminea as both a high-risk vector and a laboratory model for studying the life cycle of A. cantonensis, while highlighting P. acuta as a model for investigating parasite-snail interactions, thereby enhancing our understanding of snail-parasite dynamics in southern China.

Both host identity and environmental factors are known to influence parasite species richness. Here, we analysed selected host traits and environmental variables associated with 3 aspects of helminth diversity in African ruminants. Based on the helminth faunas of 35 species of antelope and 1 species of giraffe, we studied drivers of species richness as well as taxonomic and functional diversity, combined for all helminths and separately for nematodes, cestodes and trematodes. A larger geographic host range and/or multiple habitats were associated with higher species richness in all helminths and each group individually as well as with functional diversity in all helminths, trematodes and cestodes. A wider host distribution range and larger relative brain size were both linked to higher taxonomic diversity in all helminths, and an increase in host longevity was linked to higher taxonomic diversity in nematodes. A higher level of climate moisture, relative humidity and primary production had a positive effect on trematode species richness and taxonomic diversity in all helminths, while trematode taxonomic diversity decreased in hosts from drier areas but increased in cestodes harboured by hosts from warmer areas. Our results highlight that patterns in parasite species richness and diversity emerge from an interplay of numerous factors, including host biology, environmental conditions and ecological traits of the parasites themselves. This points to the importance of carefully choosing the range of hosts considered for large-scale parasite diversity studies and underscores the need to avoid grouping too many types of parasites when looking for ecological patterns.

Recently, the WHO published a Target Product Profile for a diagnostic test for cutaneous leishmaniasis (CL) and a Roadmap to 2030 for Neglected Tropical Diseases. The documents highlight that existing diagnostic tools for CL are insufficient, whilst setting clear goals for improved sensitivity and reduced cost. The need for species typing in diagnostics is also becoming more pressing with the emergence of drug-resistance, especially of Leishmania tropica. Serological tests are unable to do this, while techniques that can, like PCR, require complex and expensive machinery. Isothermal assays like LAMP offer a promising solution, but more work also remains, as few species-specific LAMP assays have been developed thus far and CL in Ethiopia is particularly neglected. Additionally, since the COVID-19 pandemic, many cheap isothermal diagnostic devices have been produced, which have yet to be tested in the diagnosis of CL. Finally, artificial intelligence presents another avenue for rapid diagnosis by image analysis. In this comprehensive review, we examine the opportunities and challenges inherent to diagnostic development for CL, a priority undertaking that still faces many developmental hurdles.

Hippoboscoidea flies exhibit highly specific ectoparasitic relationships with bats, shaped by both intrinsic factors (e.g. bat behaviour) and extrinsic factors (e.g. land use). Understanding the dynamics of these parasite–host interactions is essential for uncovering co-evolutionary patterns and informing conservation strategies. To this end, we studied bat–fly interactions across different elevations in a montane forest of Amazonas, northern Peru. The most abundant bats were Carollia brevicauda, C. perspicillata and Sturnira oporaphilum, while Paraeuctenodes similis and Trichobius joblingi were the most common flies. Most flies exhibited monoxenous host specificity. Bat–fly interaction networks revealed high modularity and specialization at both local and regional scales. Modules typically grouped bat species of the same genus or subfamily, suggesting that phylogenetic constraints and roosting behaviour may shape those interaction patterns. Nestedness within modules (compound structure) emerged in the aggregated regional network, aligning with the integrative hypothesis of specialization. Although network structures were broadly similar across sites, species turnover contributed to subtle differences in module composition and specialization. These differences were congruent with the changes in species roles of certain bats and flies. This study represents the first of its kind in Peru and addresses significant knowledge gaps in the ecology of bat–fly interactions in the Neotropics.

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.

Parasites can strongly influence host populations, particularly when the host is an ecosystem engineer. Oysters are ecosystem engineers that support estuarine communities and fisheries but are susceptible to 2 protozoan parasites, Perkinsus marinus (causing Dermo) and Haplosporidium nelsoni (causing MSX). Although both parasites are known to be influenced by environmental conditions, fine-scale temporal and spatial patterns remain underexplored in southeastern US estuaries. We examined parasite prevalence and intensity biweekly from April to October 2023 across 4 intertidal reefs on Sapelo Island, Georgia, and analysed concurrent water quality data (temperature, salinity, dissolved oxygen, pH) to identify potential environmental drivers of parasite prevalence and intensity. Parasite prevalence was high overall, 88% of oysters were infected with at least 1 parasite, and 34% were co-infected. Haplosporidium nelsoni prevalence was consistently high across sites, while P. marinus prevalence showed greater spatiotemporal variability, increasing through late summer and fall. Models indicated a time-lagged effect of environmental conditions on P. marinus prevalence, specifically with temperature and dissolved oxygen. Prevalence of H. nelsoni remained high throughout the year among sites and was best explained by temperature variability, salinity, and dissolved oxygen. Intensity levels did not differ among sites for either parasite. Our results demonstrate that even at small spatial scales and over time, oyster–parasite dynamics are shaped by multiple, interacting environmental factors, with time-lagged responses particularly evident for P. marinus. Understanding these dynamics is essential for predicting disease impacts under changing environmental conditions and informing management, restoration, and aquaculture strategies.

Freshwater snails are important intermediate hosts for several parasitic diseases, including fascioliosis and schistosomiosis, with significant impacts on human and animal health. In Bangladesh, vector snails have been identified only by morphology. Here, we validate the species of freshwater snails acting as intermediate hosts for Fasciola and Schistosoma spp. using molecular and bioinformatics tools. Following morphology and morphometrics, we identified 9 species of snails: Lymnaea auricularia, Lymnaea luteola, Indoplanorbis exustus, Physa acuta, Viviparus bengalensis, Brotia spp., Thiara spp. and Pila globosa. Cercarial shedding tests revealed that L. auricularia (0.72%, 7 out of 977) and L. luteola (0.36%, 8 out of 2240) shed fasciolid cercariae, which polymerase chain reaction (PCR) confirmed. But I. exustus (5.43% 19 out of 350), L. auricularia (9.42%, 92 out of 977), L. luteola 10.09% (226 out of 2240), P. acuta (2.4%, 11 out of 450) and V. bengalensis (0.14%, 7 out of 500) shed schistosomatid cercariae. The same snail did not shed both fasciolid and schistosomatid cercariae simultaneously. PCR and sequencing of the Cox1 gene confirmed the species of the intermediate hosts. The sequences of L. auricularia, L. luteola, I. exustus, P. acuta and V. bengalensis were identical (99−99.7%) to reported sequences of these species. Phylogenetic analysis revealed that sequences of the present study for each species formed well-separated clusters with the corresponding reference sequences. Taken together, the results of this study highlight the importance of molecular tools for confirming snail species and will help target specific vector snails in the particular habitat when designing snail-borne trematode control programs.

Haemonchus contortus, a highly pathogenic gastrointestinal nematode, significantly impacts small ruminant production, causing substantial economic losses in sheep and goat farming. This study examined the genetic diversity and population structure of 171 H. contortus isolates collected from the abomasa of sheep slaughtered across 8 distinct regions in Xinjiang, China. Using sequence analysis, phylogenetic reconstruction and population genetic analyses of the mitochondrial nad4 gene, we identified 163 haplotypes, with haplotype diversity ranging from 0.995 to 1.000 and nucleotide diversity from 0.02007 to 0.03145. The Tacheng population displayed the highest nucleotide diversity. Analysis of molecular variance revealed that 91.83% of genetic variation occurred within populations, with minimal differentiation among them (Fst: −0.01296 to 0.04274). Neutrality tests (Tajima’s D and Fu’s Fs) indicated no recent population bottlenecks. Phylogenetic and haplotype network analyses showed no distinct geographic clustering, suggesting extensive gene flow, likely facilitated by host movement. These findings provide critical insights into the genetic structure of H. contortus in Xinjiang, informing strategies for managing anthelmintic resistance and controlling this economically significant parasite.