Schistosomiasis, a parasitic disease caused by Schistosoma species, remains highly prevalent in tropical regions, where it contributes significantly to hepatic and vascular complications. Despite the well-established role of parasitic eggs in driving inflammation and organ damage, the specific vascular mechanisms remain poorly understood. Given the role of angiogenesis and vascular remodelling in tissue repair, the angiopoietins (ANGs) could be promising biomarkers to evaluate disease progression. This study aims to explore the relationship between ANG levels with parasitic load in patients with schistosomiasis. In this cross-sectional study, 126 schistosomiasis patients were stratified into three groups based on parasitic egg burden: negative, low, and moderate/high. Demographic, clinical, and laboratory data were collected, and serum ANGs were quantified via enzyme-linked immunosorbent assays. Parasitic load was assessed through stool examination, quantifying the number of Schistosoma eggs per gram of faeces. Additional clinical parameters, including liver abnormalities and blood chemistry, were evaluated. The ANG-2 levels and the ANG-2/ANG-1 ratio were significantly elevated in patients with higher egg burdens, particularly in the moderate/high group. The ANG-2/ANG-1 ratio was notably higher in patients with hepatosplenic schistosomiasis. While systemic blood pressure and oxygen saturation showed no significant differences between groups, patients with elevated triglycerides had lower ANG-2 levels. Elevated ANG-2 levels and an increased ANG-2/ANG-1 ratio correlate with higher parasitic burdens, reinforcing their potential as biomarkers for disease severity. These findings underscore the role of egg-induced inflammation in schistosomiasis pathophysiology and suggest that ANGs could aid in early diagnosis and treatment decisions, particularly in populations with high parasitic loads.

The impact of macroparasites on their hosts is proportional to the number of parasites per host, or parasite abundance. Abundance values are count data, i.e. integers ranging from 0 to some maximum number, depending on the host–parasite system. When using parasite abundance as a predictor in statistical analysis, a common approach is to bin values, i.e. group hosts into infection categories based on abundance, and test for differences in some response variable (e.g. a host trait) among these categories. There are well-documented pitfalls associated with this approach. Here, I use a literature review to show that binning abundance values for analysis has been used in one-third of studies published in parasitological journals over the past 15 years, and half of the studies in ecological and behavioural journals, often without any justification. Binning abundance data into arbitrary categories has been much more common among studies using experimental infections than among those using naturally infected hosts. I then use simulated data to demonstrate that true and significant relationships between parasite abundance and host traits can be missed when abundance values are binned for analysis, and vice versa that when there is no underlying relationship between abundance and host traits, analysis of binned data can create a spurious one. This holds regardless of the prevalence of infection or the level of parasite aggregation in a host sample. These findings argue strongly for the practice of binning abundance data as a predictor variable to be abandoned in favour of more appropriate analytical approaches.

Schistosomiasis remains a significant public health concern in sub-Saharan Africa, particularly among women and children. In Cameroon, urogenital and intestinal schistosomiasis affect the lives of millions of impoverished populations, and female genital schistosomiasis (FGS) remains a serious threat which has not been quantified explicitly. The extent of stigmatization and discrimination related to FGS is currently unknown. This study explores the use of precision mapping to identify high-risk communities for urogenital schistosomiasis and guide targeted screening for FGS. Parasitological surveys were conducted between November 2020 and July 2021 in four health districts using urine filtration and Kato-Katz techniques, first in schools to identify areas of higher transmission, and secondly in selected high-risk communities. Geographic information system tools were employed to identify high transmission foci and households of targeted infected women. Results of surveys in schools showed no schistosomiasis transmission in Ayos (0%) and low prevalence in Akonolinga (8%), while Bertoua and Doume had high prevalence, up to 33% and 48% infection with Schistosoma haematobium, respectively. These results made the two health districts of Bertoua and Doume suitable for focused FGS investigations. Surveys in communities revealed higher schistosomiasis prevalence and infection intensity in Doume compared to Bertoua. Precision mapping effectively identified infected women and enabled targeted recruitment for further clinical studies, facilitating efficient resource allocation for gynaecological follow-up. This approach demonstrates the value of geospatial tools in enhancing targeted public health interventions, disease surveillance and control strategies.

We investigated the effects of body mass, geographic range size, the within-range richness of host assemblages (diversity field) and the habitat breadth of small mammalian hosts from 6 biogeographic realms on the species richness of their flea and gamasid mite faunas. We also tested whether the probability of between-host ectoparasite sharing is related to host phylogenetic relatedness, trait similarity or geographic distance/environmental dissimilarity between their ranges. We asked whether the effects of host-associated determinants of ectoparasite richness and the probability of ectoparasite sharing differ between (1) biogeographic realms and (2) fleas and mites. Whenever significant effects of host body mass on ectoparasite richness were found, they were negative, whereas the significant effects of geographic range size, diversity field and habitat breadth were positive. The occurrence of each determinant’s effects on ectoparasite species richness differed (1) within fleas or mites between realms and (2) between fleas and mites within a realm. In all realms, the probability of a flea or a mite species being shared between hosts decreased with a decrease in the hosts’ phylogenetic relatedness, trait similarity, geographic distance between ranges or environmental similarity. The probabilities of an ectoparasite species being shared between hosts were most strongly related to the hosts’ trait similarity and were least related to the environmental similarity. We conclude that caution is needed in making judgements about the generality of macroecological patterns related to parasites based on the investigations of these patterns in limited numbers of localities and when pooling data on various taxa.

The rat lungworm Angiostrongylus cantonensis is a zoonotic metastrongyloid nematode, currently considered an emerging pathogen approaching Europe. In tropics and subtropics, it is an important food-borne neurotropic parasite of medical and veterinary importance. Sources of infection for mammals and birds include gastropod intermediate hosts and poikilothermic vertebrates (paratenic hosts). To evaluate the relevance of reptiles in the rat lungworm circulation, we performed an experimental series focused on long-term survival of third stage larvae (L3) of A. cantonensis in reptiles and potential of saurians to serve as a source of infection for further hosts. Twenty leopard geckos (Eublepharis macularius) were infected with varying doses of L3 (100, 1000, 10 000 larvae per animal). Live L3 were collected from all infected geckos (mostly in musculature and liver) euthanized 1–6 months after the infection and were proven to be infective for Wistar rats (definitive hosts). Three sacrificed geckos were subsequently fed to three corn snakes (Pantheropis guttatus) to test hypothesis of L3 infectivity for predators positioned higher in the food chain. Snakes were euthanized 1 month post-infection and live L3 were detected predominantly in the intestinal wall. The animals remained clinically healthy throughout the study. No reptiles showed significant changes in haematological and biochemical blood parameters, though elevated CK and GLDH were observed in most geckos in the group receiving higher infectious dose. This study highlights the significant potential of reptiles to play a crucial role in the circulation of metastrongyloid nematodes in food web and in their transmission to humans.

Chemotaxis is the phenomenon of sensing external concentration gradients by cells and the cellular movement towards or away from the cells. While there have been intensive studies on prokaryotes, little research has been conducted on the chemotaxis in flagellated eukaryotes, such as Giardia lamblia (G. lamblia) and Trichomonas vaginalis (T. vaginalis). The current study uses a 2-chamber assay to discuss the motility of G. lamblia and T. vaginalis towards simple sugars. The cells were observed moving towards the sugars in a concentration and time-dependent manner. Furthermore, the cell movements were independent of change in osmolarity. Experiments compared the motility of the parasites grown in TYI-S-33 medium and TYI-S-33 medium without glucose (starvation media). It was noted that the starved cells showed a better chemotactic response towards the carbohydrates than the non-starved cells.

Plasmodium simium, a parasite of platyrrhine monkeys, is known to cause human malaria outbreaks in Southeast Brazil. It has been hypothesized that, upon the introduction of Plasmodium vivax into the Americas at the time of the European colonization, the human parasite adapted to neotropical anophelines of the Kerteszia subgenus and to local monkeys, along the Atlantic coast of Brazil, to give rise to a sister species, P. simium. Here, to obtain new insights into the origins and adaptation of P. simium to new hosts, we analysed whole-genome sequence (WGS) data from 31 P. simium isolates together with a global sequence dataset of 1086 P. vivax isolates. Population genomic analyses revealed that P. simium comprises a discrete parasite lineage with greatest genetic similarity to P. vivax populations from Latin America – especially those from the Amazon Basin of Brazil – and to ancient European P. vivax isolates, consistent with Brazil as the most likely birthplace of the species. We show that P. simium displays half the amount of nucleotide diversity of P. vivax from Latin America, as expected from its recent origin. We identified pairs of sympatric P. simium isolates from monkeys and from humans as closely related as meiotic half-siblings, revealing ongoing zoonotic transmission of P. simium. Most critically, we show that P. simium currently causes most, and possibly all, malarial infections usually attributed to P. vivax along the Serra do Mar Mountain Range of Southeast Brazil.

Identifying interactions between species is essential for understanding ecosystem dynamics. With their central position in trophic networks, anurans underscore the importance of studying their interactions with other organisms. Traditionally, collecting and describing anuran helminth parasites rely on lethal methods, posing challenges for studying threatened species. In this study, we tested the effectiveness of non-invasive fecal metabarcoding and compared its accuracy to traditional invasive methods for identifying parasites and dietary components. We collected anurans from 6 families in the Brazilian Atlantic Rainforest and analysed their feces using the 18S marker while performing necropsies for traditional identification. Traditional methods identified 12 parasite taxa and 3 dietary items at lower taxonomic resolution. Fecal metabarcoding, on the other hand, revealed greater diversity and fine taxonomic resolution for dietary items, although with lower accuracy for parasites due to database limitations. The metabarcoding approach demonstrated a high potential for non-lethal biodiversity assessments, offering a more comprehensive view of dietary diversity and a viable alternative for studying parasites in vulnerable populations. However, its effectiveness depends on improving reference databases, especially for parasite taxa. The advancement of non-invasive approaches that integrate parasitological data holds great potential to improve conservation strategies and enhance the ecological understanding of amphibian-parasite interactions.

Toxoplasma gondii is a protozoan parasite that causes infection in birds and mammals (terrestrial and marine), both domestic and wild. The state of Tabasco has favourable climatic and ecological conditions for the replication and dissemination of this parasite. Therefore, the aim of this study was to isolate and genotype T. gondii from free-range chickens in this region of México by PCR-RFLP of 15 genetic markers. A total of 12 chickens were obtained from 7 municipalities. Serological survey by the modified agglutination test (MAT) of chicken serum samples revealed that 9 out of the 12 chickens (75%) tested had antibodies against T. gondii (titres ≥ 1:10). Toxoplasma gondii DNA was detected by PCR in tissues from 8 out of the 12 chickens. Twelve viable strains of T. gondii were isolated from the heart and brain samples of eight chickens by bioassay in mice. Genetic characterization of tachyzoite-derived DNA was performed using 10 multilocus RFLP-PCR genotyping markers (SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1 and Apico) and five virulence-related markers (CS3, ROP5, ROP16, ROP17 and ROP18). A total of 6 ToxoDB PCR-RFLP genotypes were identified, including #8 (also known as Type BrIII), #28, #38, and 3 new genotypes designated as #344, #345 and #346. Combination of ROP18/ROP5 alleles were 1/3, 3/3 and 4/3. ToxoDB #344 and #345 genotypes also had a new allele at the ROP5 locus. These results suggest high genetic diversity of T. gondii in southeastern México.

In many areas of The Gambia, West Africa, population crowding in a degraded environment has forced close interactions of diurnal primate species with humans. We assessed intestinal parasitic infection prevalence and diversity in 4 diurnal non-human primate (NHP) species, Chlorocebus sabaeus, Erythrocebus patas, Papio papio and Piliocolobus badius across 13 sampling sites. The effect of human activity, determined by the human activity index, and NHP group size on parasite richness was assessed using a generalized linear mixed model (GLMM). The most common protozoa identified were Entamoeba coli (30%) and Iodamoeba buetschlii (25%). The most common helminths were Strongyloides fuelleborni (11%), Oesophagostomum spp. (9%) and Trichuris trichiura (9%). Two of six (6%) Cyclospora spp. infections detected sequenced as Cyclospora cercopitheci (both in C. sabaeus). The more arboreal P. badius trended towards a lower prevalence of intestinal parasites, although this was not statistically significant (χ2 P = 0.105). Human activity or group size did not have any significant effect on parasite richness for P. badius (P = 0.161 and P = 0.603) or P. papio (P = 0.817 and P = 0.607, respectively). There were insufficient observations to fit a GLMM to E. patas or C. sabaeus. Our reports present the richness and diversity of intestinal parasites in 4 diurnal NHPs in The Gambia, West Africa. Despite desertification and habitat loss, our results indicate that the prevalence and diversity of intestinal parasites in Gambian NHPs are seemingly unaffected by human activity. Further investigation with a larger dataset is required to better elucidate these findings.

In Africa, female genital schistosomiasis (FGS) damages women’s health. In Cameroon, diagnosis is rare and healthcare workers lack knowledge. Clinicians can be trained to identify FGS lesions, but the accuracy is uncertain. We assessed the acceptability and feasibility of FGS screening in Cameroon’s East Province by comparing static HIV clinics and mobile pop-up clinics through consultations and acceptance rates, guided by precise disease mapping. A clinician was remotely trained to diagnose FGS lesions, with success measured by expert comparison using cervix images. The proportion of FGS was compared between settings. A total of 1242 women were approached, 624 in the HIV clinics and 618 in the mobile clinics, respectively. Women at HIV clinics were significantly older [37.0 years (interquartile range, IQR: 31–43)] than those at mobile clinics [28.5 years (IQR: 23–36)]. Refusal of the screening procedures was significantly higher in the HIV clinics (50%) than in the mobile clinics (31%). FGS lesions were present in over half of women examined, 51% in the HIV clinic and 56% in the community. The diagnostic concordance between clinicians was more than 90%. It is both feasible and acceptable to identify and treat FGS lesions in areas without specialized care. Mobile pop-up clinics’ acceptability is better, with younger women participating which helps to better rectify age-inequities in FGS surveillance, and remote telemedicine training is effective. Prevalence of FGS suspect lesions was very high in both settings.

Toxoplasmosis, caused by the obligate intracellular parasite Toxoplasma gondii, is one of the most prevalent zoonotic parasitic infections worldwide. When acquired during pregnancy, T. gondii can be transmitted to the fetus, with clinical outcomes influenced by gestational age at time of infection and the parasite’s genotype. Prenatal screening enables the detection of maternal seroconversion and offers a critical window for intervention. In Uruguay, despite mandatory serological screening during pregnancy, national data on T. gondii seroprevalence and maternal seroconversion have not been updated in two decades. In addition, the genetic diversity of local strains remains poorly characterized. In this study, we analysed publicly available serological data from pregnant individuals attending Uruguay’s largest public maternity hospital between 2019 and 2023. We found that seroprevalence has modestly declined from 50% (reported in 1998) to 45.5%, with a congenital transmission rate of 0.58%. Clinical analysis of affected newborns revealed chorioretinitis as the predominant manifestation. To investigate parasite diversity, we performed genotyping of T. gondii strains using in silico PCR-RFLP following molecular detection. Our findings revealed substantial genetic diversity, including novel allele combinations not previously described in the region. These results highlight both the continued public health burden and the evolving genetic landscape of T. gondii in Uruguay. Our findings underscore the need to strengthen surveillance and prevention strategies for congenital toxoplasmosis in South America.

Heartwater is a tick-borne disease (TBD) of wild and livestock ruminants that threatens food security and the economy throughout much of Africa. Furthermore, the geographic range of heartwater is expanding and is predicted to continue doing so. Despite this, our understanding of heartwater dynamics lags far behind that of many other TBDs. We are therefore limited in our ability to design effective disease control strategies. In this study, we derive and analyse a mathematical model of heartwater dynamics. We analyse our model to predict the most influential parameters for disease risk, both in terms of new outbreaks and in heartwater-endemic regions. We show that the host-finding efficiency of ticks is the most influential parameter affecting outbreak risk. Also, outbreak risk is highly sensitive to the impact of the heartwater pathogen on tick fitness – a previously unexplored concept for any TBD system. In areas where heartwater is established, we show that disease can be controlled via enzootic stability (prolonged host immunity attained via frequent pathogen exposure). However, the maintenance of enzootic stability was dependent on several ecological and physiological parameters. Regarding practical output, we suggest prioritizing tick control measures during periods when ticks are most active in terms of dispersing towards hosts, so as to mitigate heightened outbreak risk. In addition, given the specificity of conditions required for enzootic stability, we caution against relying solely on enzootic stability for long-term heartwater protection. More broadly, our study highlights important tick life history parameters that have been neglected by previous TBD models.

Common peccaries (Tayassu pecari), wild boars (Sus scrofa) and collared peccaries (Dicotyles tajacu) are species that have gained attention in Brazil because of their close relationship with human beings, their influence on the environment and the parasitic fauna they host, which is common in free-ranging animals. In this study, we obtained the carcasses S. scrofa (n = 4), T. pecari (n = 12) and D. tajacu (n = 1) that were killed by hunting (only wild boars), or by being run over or burned. The animals were necropsied and searched for parasites. The parasites found in the gastrointestinal tract were fixed in ethanol for morphological identification. The parasites identified were Ascaris suum, Monodontus rarus, Monodontus semicircularis, Strongyloides spp., Lagochilascaris minor, Eucyathostomum dentatum, Oligacanthorhynchus major and Ascarops strongylina. In addition to observing the occurrence of different species of parasites in tayassuids and suids, we also aimed to raise awareness among the population about the dangers of consuming these animals, as well as the importance of ecological relationships for the propagation of parasitic fauna. Our results indicate that parasites are host switching, possibly related to the adaptation of L. minor and M. rarus.

Liberia (West Africa) has an extensive (co)burden of urogenital and intestinal schistosomiasis; each largely restricted to more inland areas. Where urogenital schistosomiasis is endemic, as both disease surveillance and case management are nascent, many women may unknowingly be living with Female Genital Schistosomiasis (FGS). Using a recently developed FGS score card, we appraised FGS score card valuations with point-of-care gynaecological and molecular parasitological evaluations as undertaken within typical primary care settings of four Liberian counties. A total of 400 women, 100 participants from each of four endemic inland counties, underwent a cursory gynaecological examination using a speculum for visible FGS lesions, undertaken by a midwife, and provided a urine sample that was examined by centrifugation with microscopy for Schistosoma ova. Urine-sediments in ethanol were later analysed with a high-resolution melt (HRM) real-time (rt) PCR assay to screen for Schistosoma genetic markers. Using a combination of clinical and parasitological information, overall prevalence of UGS and FGS was <10% and a single case of putative FGS-associated co-infection with Schistosoma mansoni was observed. Participant interviews with the FGS score cards provided an insight into at-risk lifestyle and environmental factors, e.g. women who fished regularly were more likely to present with FGS whereas those who lived > 15 km from a local river were less likely to present with FGS. In this resource-poor setting of Liberia, active surveillance for FGS with either clinical or parasitological methods remains challenging such that sole future use of the FGS score card is most pragmatic for primary care.

Urogenital schistosomiasis (UGS) caused by zoonotic or hybrid schistosome infection(s) is an emerging public health concern in Malawi, and we describe a 1-year clinical sub-study with 3 inspection time points for female genital schistosomiasis (FGS) upon selecting 86 women with proven UGS. This sub-study was set within a broader 2-year longitudinal ‘Hybridization in UroGenital Schistosomiasis (HUGS)’ investigation. A detailed cervicovaginal examination with a portable colposcope was conducted, examining cervicovaginal lavage (CVL), cervical swab, cervical biopsy and urine with traditional parasitological and molecular diagnostic methods. At baseline, overt FGS by colposcopy was 72.1%, 64.3% by CVL real-time PCR and 51.2% by both colposcopy and CVL-PCR, noting urine-microscopy could often be negative. Human papillomavirus was detected in 31.0% of the cervical swabs, with 8.3% women also FGS positive by colposcopy and real-time PCR. Over the year, FGS prevalence by colposcopy increased by 32.7% during the study to 84.6%, homogenous yellow and grainy sandy patches being very common in the youngest 18–25 age group, where 51.9% were positive. FGS appears widespread locally and we discuss difficulties in its detection without invasive sampling. In addition to the presence of S. haematobium, S. mattheei was noted alongside key concurrent sexually transmitted infections. From our findings, we point out that improved prevention and management of FGS is required, foremost, better availability and regular accessibility to praziquantel treatment is needed. Furthermore, targeted health education, raised community awareness and dovetailing synergistic public health activities within Sexual and Reproductive Health services and local HIV/AIDS programmes could develop an appropriate holistic health intervention package.

Female genital schistosomiasis (FGS) is a chronically disabling gynaecological condition, impacting up to 56 million women and girls, mostly in sub-Saharan Africa. In lieu of a gold standard laboratory test, it is possible to diagnose FGS visually. Visual diagnosis is performed through inspection of the cervix and surrounding tissue to identify signs of Schistosoma egg deposition, associated inflammation and granuloma formation. The change related to egg deposition can be very subtle and heterogeneous and is often seen in the context of other altered cervical morphology. Visual diagnostics for FGS are therefore currently highly subjective and lack specificity, with low consistency of grading between trained expert reviewers. Computer vision, driven by artificial intelligence, is an enticing prospect to overcome these issues due to the potential to accurately detect and classify the subtle changes and patterns that are indiscernible to human graders. Computer vision also offers the opportunity to support resource-constrained regions with few staff trained on visual diagnostics. However, several challenges stand in the way of progressing and successfully implementing computer vision tools for FGS. These challenges are particularly related to the variation in the appearance of the cervix (with or without disease) and FGS lesions, as well as the difficulty with accurately labelling cervical images. Exploring alternative annotation methods and model architectures is likely to improve the performance of FGS computer vision tools. This paper will explore the challenges of FGS computer vision and provide suggestions on how to overcome these barriers to enhance visual diagnostics for FGS.