Multiple Parasite Species Research Articles

Optimization of 18 S rRNA metabarcoding for the simultaneous diagnosis of intestinal parasites

Recent advancements in next-generation sequencing (NGS) technologies have created new opportunities for comprehensive screening of multiple parasite species. In this study, we cloned the 18 S rDNA V9 region of 11 species of intestinal parasites into plasmids. Equal amounts and concentrations of these 11 plasmids were pooled, and amplicon NGS targeting the 18 S rDNA V9 region was performed using the Illumina iSeq 100 platform. A total of 434,849 reads were identified, and all 11 parasite species were detected, although the number of output reads for each parasite varied. The read count ratio, in descending order, was as follows: Clonorchis sinensis, 17.2%; Entamoeba histolytica, 16.7%; Dibothriocephalus latus, 14.4%; Trichuris trichiura, 10.8%; Fasciola hepatica, 8.7%; Necator americanus, 8.5%; Paragonimus westermani, 8.5%; Taenia saginata, 7.1%; Giardia intestinalis, 5.0%; Ascaris lumbricoides, 1.7%; and Enterobius vermicularis, 0.9%. We found that the DNA secondary structures showed a negative association with the number of output reads. Additionally, variations in the amplicon PCR annealing temperature affected the relative abundance of output reads for each parasite. These findings can be applied to improve parasite detection methodologies and ultimately enhance efforts to control and prevent intestinal parasitic infections.

Influence of body size and environmental conditions on parasite assemblages of the black-spotted croaker (Protonibea diacanthus) (Teleostei: Sciaenidae) in northern Australia.

The functioning and richness of marine systems (and biological interactions such as parasitism) are continuously influenced by a changing environment. Using hierarchical modelling of species communities (HMSC), the presence and abundance of multiple parasite species of the black-spotted croaker, Protonibea diacanthus (Sciaenidae), was modelled against environmental measures reflecting seasonal change. Protonibea diacanthus were collected in three seasons across 2019–2021 from four locations within the waters of the Northern Territory, Australia. The length of P. diacanthus proved to have a strong positive effect on the abundance of parasite taxa and overall parasitic assemblage of the sciaenid host. This finding introduces potential implications for parasitism in the future as fish body size responds to fishing pressure and climate changes. Of the various environmental factors measured during the tropical seasons of northern Australia, water temperature and salinity changes were shown as potential causal factors for the variance in parasite presence and abundance, with changes most influential on external parasitic organisms. As environmental factors like ocean temperature and salinity directly affect parasite–host relationships, this study suggests that parasite assemblages and the ecological functions that they perform are likely to change considerably over the coming decades in response to climate change and its proceeding effects.

Prevalence of gastrointestinal parasites in domestic pigs from family farms in northeastern Argentina

Domestic pigs serve as significant hosts and reservoirs for multiple parasite species, some specific to pigs and many others of zoonotic importance. This study aimed to assess the prevalence of intestinal parasites in pigs within a rural area in northeastern Argentina. We also examined demographic information, breeding conditions, and exposure factors associated with parasite presence. Pig feces were subjected to coprological examination through flotation and sedimentation techniques. Modified Ziehl-Neelsen technique was employed to examine oocysts of Cryptosporidium spp. In total, 29 family farms with pig pens were analyzed, and 42 stool samples were collected from pigs on these farms. At the farm level, the presence of at least one parasite species was recorded in 27 rural houses (93.1%). We found that 90.4% of pigs were parasitized, with a specific parasitoses of 10 species, with a maximum of six species in a single host. The most prevalent protozoa were Entamoeba spp. (57.1%) and Blastocystis sp. (45.2%), followed by Iodamoeba butschlii (33.3%), Neobalantidium coli (21.4%), coccidia (14.2%), Cryptosporidium spp. (9.5%) and Giardia spp. (2.3%). The most prevalent helminths were Strongylidae eggs (52.3%), Ascaris spp. (14.2%) and Trichuris spp. (2.3%). We advocate for an urgent need to implement a comprehensive prophylaxis program prioritizing general hygiene practices such as regular cleaning, removal of fecal material and renewal of drinking water. Additionally, vaccination and deworming protocols should be implemented. Furthermore, this study highlights the necessity for molecular-level evaluations to detect potential zoonotic genotypes of the identified protozoa.

Harnessing cholesterol uptake of malaria parasites for therapeutic applications

Parasites, such as the malaria parasite P. falciparum, are critically dependent on host nutrients. Interference with nutrient uptake can lead to parasite death and, therefore, serve as a successful treatment strategy. P. falciparum parasites cannot synthesise cholesterol, and instead source this lipid from the host. Here, we tested whether cholesterol uptake pathways could be ‘hijacked’ for optimal drug delivery to the intracellular parasite. We found that fluorescent cholesterol analogues were delivered from the extracellular environment to the intracellular parasite. We investigated the uptake and inhibitory effects of conjugate compounds, where proven antimalarial drugs (primaquine and artesunate) were attached to steroids that mimic the structure of cholesterol. These conjugated antimalarial drugs improved the inhibitory effects against multiple parasite lifecycle stages, multiple parasite species, and drug-resistant parasites, whilst also lowering the toxicity to human host cells. Steroids with introduced peroxides also displayed antimalarial activity. These results provide a proof-of-concept that cholesterol mimics can be developed as a drug delivery system against apicomplexan parasites with the potential to improve drug efficacy, increase therapeutic index, and defeat drug resistance.

Faecal egg count reduction tests and nemabiome analysis reveal high frequency of multi-resistant parasites on sheep farms in north-east Germany involving multiple strongyle parasite species

Anthelmintic resistance in sheep parasitic gastrointestinal nematodes is widespread and a severe health and economic issue but prevalence of resistance and involved parasite species are unknown in Germany. Here, the faecal egg count reduction test (FECRT) was performed on eight farms using fenbendazole, ivermectin and moxidectin and on four farms using only moxidectin. A questionnaire was used to obtain data on management practices to potentially identify risk factors for presence of resistance. All requirements of the recently revised WAAVP guideline for diagnosing anthelmintic resistance using the FECRT were applied. Nematode species composition in pre- and post-treatment samples was analysed with the nemabiome approach. Using the eggCounts statistic package, resistance against fenbendazole, ivermectin and moxidectin was found on 7/8, 8/8 and 8/12 farms, respectively. No formal risk factor analysis was conducted since resistance was present on most farms. Comparison with the bayescount R package results revealed substantial agreement between methods (Cohen's κ = 0.774). In contrast, interpretation of data comparing revised and original WAAVP guidelines resulted in moderate agreement (Cohen's κ = 0.444). The FECR for moxidectin was significantly higher than for ivermectin and fenbendazole. Nemabiome data identified 4 to 12 species in pre-treatment samples and treatments caused a small but significant decrease in species diversity (inverse Simpson index). Non-metric multidimensional scaling and k-means clustering were used to identify common patterns in pre- and post-treatment samples. However, post-treatment samples were scattered among the pre-treatment samples. Resistant parasite species differed between farms. In conclusion, the revised FECRT guideline allows robust detection of anthelmintic resistance. Resistance was widespread and involved multiple parasite species. Resistance against both drug classes on the same farm was common. Further studies including additional drugs (levamisole, monepantel, closantel) should combine sensitive FECRTs with nemabiome data to comprehensively characterise the anthelmintic susceptibility status of sheep nematodes in Germany.

Variation in prevalence and intensity of macroparasites in moose and their interactions with winter tick load in eastern Canada

Wild animals are infected with a large diversity and abundance of parasites that can affect their behavior, growth, body condition, and ultimately their survival. Although the adverse effects of parasites and the mechanisms involved in the interactions between a host and its parasites are generally well studied, much less is known about the additive or synergistic effects of multiple parasite species on a host. Moose populations in eastern Canada are infected by several species of endoparasites. In the last decades, the intensity of infestations by winter ticks, an ectoparasite, on moose have increased as a result of increased moose densities and favorable weather conditions that benefit winter tick survival. We aimed to document the diversity, intensity, prevalence, and distribution of different parasite species of moose in southern Quebec, Canada. We then evaluated the potential interaction between winter tick and endoparasites of moose, and we evaluated the effect of the simultaneous presence of ticks and endoparasites on moose body condition. To do so, we collected organs to identify and count endoparasite species, estimate winter tick abundance, and measure subcutaneous fat thickness from 174 hunted moose in fall 2019 in 8 regions of Quebec. Our results showed that the prevalence and intensity of winter tick and gastrointestinal parasites differed among regions, as well as the prevalence of the heart parasite Taenia krabbei and the intensity of lung parasite Echinoccocus granulosus. Moose body condition, however, was not influenced by the simultaneous presence of winter tick and endoparasites. The documentation of the interactive effects of multiple parasite species on a host is fundamental given that future environmental conditions in temperate climate will favor the reproduction, development, and survival of several parasite species, which could affect parasite diversity and abundance in the environment and modify host–parasite dynamics.

Coinfection of slime feather duster worms (Annelida, Myxicola) by different gregarine apicomplexans (Selenidium) and astome ciliates reflects spatial niche partitioning and host specificity.

Individual organisms can host multiple species of parasites (or symbionts), and one species of parasite can infect different host species, creating complex interactions among multiple hosts and parasites. When multiple parasite species coexist in a host, they may compete or use strategies, such as spatial niche partitioning, to reduce competition. Here, we present a host–symbiont system with two species of Selenidium (Apicomplexa, Gregarinida) and one species of astome ciliate co-infecting two different species of slime feather duster worms (Annelida, Sabellidae, Myxicola) living in neighbouring habitats. We examined the morphology of the endosymbionts with light and scanning electron microscopy (SEM) and inferred their phylogenetic interrelationships using small subunit (SSU) rDNA sequences. In the host ‘Myxicola sp. Quadra’, we found two distinct species of Selenidium; S. cf. mesnili exclusively inhabited the foregut, and S. elongatum n. sp. inhabited the mid to hindgut, reflecting spatial niche partitioning. Selenidium elongatum n. sp. was also present in the host M. aesthetica, which harboured the astome ciliate Pennarella elegantia n. gen. et sp. Selenidium cf. mesnili and P. elegantia n. gen. et sp. were absent in the other host species, indicating host specificity. This system offers an intriguing opportunity to explore diverse aspects of host–endosymbiont interactions and competition among endosymbionts.

Relationship between two pathogens in an amphibian community that experienced mass mortalities.

Because host species tend to harbor multiple parasitic species, coinfection in a host is common. The chytrid fungus Batrachochytrium dendrobatidis (Bd) and the viruses in the genus Ranavirus (Rv) are responsible for the decline of amphibians worldwide. Despite wide geographical co-occurrence and the serious conservation problem that coinfection with these pathogens could represent, little is known about their possible synergistic interactions and effects in a host community. We investigated the occurrence and associations between these two pathogens in an amphibian community after Rv-driven disease outbreaks were detected in four populations of the Iberian ribbed newt (Pleurodeles waltl) in northwestern Spain. We collected tissue samples from amphibians and fish and estimated Bd and Rv infection loads by qPCR. A few months after the most recent mass mortality event, Rv infection parameters at the affected sites decreased significantly or were lower than such registered at the sites where no outbreaks were recorded. Both pathogens were simultaneously present in almost all sites, but coinfection in a single host was rare. Our findings suggest that the co-occurrence of Bd and Rv does not predict adverse outcomes (e.g., enhanced susceptibility of hosts to one pathogen due to the presence or infection intensity of the other) following an outbreak. Other variables (such as species identity or site) were more important than infection with a pathogen in predicting the infection status and severity of infection with the other pathogen. Our results highlight the importance of host-specific and environmental characteristics in the dynamics of infections, coinfection patterns, and their impacts.

Molecular Identification of Selected Cervid Helminths in Supplementarily Fed European Bison Population

Background: Wild animals often suffer from infections with multiple species of parasites simultaneously. The exchange of parasites between different host species is common in nature and often involves intermediate hosts or sharing space such as pastures or watering holes. Supplementary feeding, leading to large aggregations of individuals, can have several adverse effects on wild ungulate populations, despite being a widespread management practice. One such effect is an increased risk of parasitic infections, particularly in social animals. We quantified the prevalence of selected helminths typically found in cervids, in samples of the European bison faeces, using molecular methods, and compared endoparasite species richness between supplementarily fed and nonfed European bison herds in the Białowieża Primeval Forest, NE Poland.Methods: Using the diagnostic PCR method, we analysed the faecal samples for molecular markers of nine parasite species which are typically found in cervids: moose, red deer, and roe deer.Results: All analysed samples tested positive for at least one parasite species, and the average number of parasite species per sample was 3.2. The most prevalent parasites were gastrointestinal nematodes: Ostertagia leptospicularis and Ostertagia antipini, found in 89.2% and 50.6% of the European bison faecal samples, respectively. We found significant differences in the prevalence of four parasite species between supplementarily fed and nonfed European bison herds. Co‐occurrence analysis showed that most of the associations between parasite species pairs were random.Conclusion: Management practices, such as supplementary feeding, can influence the spread of parasite infections in social mammals. This study also promotes the application of molecular methods for noninvasive parasitological monitoring of wildlife populations of endangered ruminant species sharing resources with other ungulates.

Prevalence of Gastrointestinal Parasitic Infections and Associated Risk Factors Among Secondary School Students in Wonji Shoa, Adama District, East Shoa Zone, Oromia Region, Ethiopia

Intestinal parasitic infections (IPIs) remain a significant contributor to morbidity and mortality globally, particularly in developing countries such as Ethiopia. Periodic assessments of IPI prevalence are essential prerequisite for effective control measures. Therefore, this cross‐sectional study is aimed at determining the prevalence of gastrointestinal parasitic infections and associated risk factors among schoolchildren at Wonji Shoa Secondary School, East Shoa Zone, Adama district, Oromia region, Ethiopia, between January and June 2022. A simple random stratified sampling technique was employed to select participants. Sociodemographic and risk factor data were collected using a structured questionnaire. Stool samples were examined to identify parasites. Data were analyzed using SPSS version 20. Descriptive statistics, chi‐square tests, and logistic regression were conducted to assess associations between variables and then the strength of the association. A p value < 0.05 was considered statistically significant. Of the 403 selected students, 330 completed the study that makes 81.89% response success. The overall IPI prevalence was 16.66% (55/330), with a higher prevalence among males (60%, 33/55) than females (40%, 22/55). Five parasite species were identified: two protozoa (Entamoeba histolytica and Giardia lamblia) with a combined prevalence of 9.70% (32/330) and three helminths (Ascaris lumbricoides, Hymenolepis nana, and Taenia spp.) with a combined prevalence of 6.97% (23/330). Cysts were detected in 62.5% of E. histolytica cases (15/24), and eggs were detected in 76.92% of A. lumbricoides cases (10/13). The study revealed a substantial IPI prevalence (16.66%) among the students. This finding underscores the need for effective prevention and control strategies. The predominance of parasitic infections among males is notable requiring further investigation of the factors. The identification of multiple parasite species indicates a complex epidemiological scenario. The presence of protozoan cysts and helminthic eggs highlights the potential for fecal‐oral transmission and the importance of improved sanitation and hygiene practices.

Multiplex Assays for Analysis of Antibody Responses to South Asian Plasmodium falciparum and Plasmodium vivax Malaria Infections.

Malaria remains a major global health challenge, causing over 0.6 million yearly deaths. To understand naturally acquired immunity in adult human populations in malaria-prevalent regions, improved serological tools are needed, particularly where multiple malaria parasite species co-exist. Slide-based and bead-based multiplex approaches can help characterize antibodies in malaria patients from endemic regions, but these require pure, well-defined antigens. To efficiently bypass purification steps, codon-optimized malaria antigen genes with N-terminal FLAG-tag and C-terminal Ctag sequences were expressed in a wheat germ cell-free system and adsorbed on functionalized BioPlex beads. In a pilot study, 15 P. falciparum antigens, 8 P. vivax antigens, and a negative control (GFP) were adsorbed individually on functionalized bead types through their Ctag. To validate the multiplexing powers of this platform, 10 P. falciparum-infected patient sera from a US NIH MESA-ICEMR study site in Goa, India, were tested against all 23 parasite antigens. Serial dilution of patient sera revealed variations in potency and breadth of antibodies to various parasite antigens. Individual patients revealed informative variations in immunity to P. falciparum versus P. vivax. This multiplex approach to malaria serology captures varying immunity to different human malaria parasite species and different parasite antigens. This approach can be scaled to track the dynamics of antibody production during one or more human malaria infections.

Effects of water temperature and light/dark cycles on in vitro egg laying and hatching of the monogenean Microcotyle sebastis on Korean rockfish (Sebastes schlegelii)

Aquaculture faces increasing challenges from parasitic infections, notably impacting the marine cage farming of Korean rockfish (Sebastes schlegelii). A primary contributor to these challenges is the monogenean parasite Microcotyle sebastis, which incurs significant economic losses. To formulate effective management strategies, it is essential to understand how environmental variables influence the reproductive behavior and survival of M. sebastis. In this study, we conducted controlled in vitro experiments to assess the fecundity, hatching success, and viability of M. sebastis across a temperature range from 25 °C to 4 °C, as well as under varying light/dark conditions. We found that the parasite's fecundity was optimal at 15 °C and minimal at 4 °C. Survival rates exhibited an inverse correlation with increasing temperatures. The hatching process was most rapid at 25 °C, with no hatching observed at 4 °C. Upon hatching, the maturation and lifespan of oncomiracidia varied depending on temperature: cilia degenerated within 36 h at temperatures ranging from 25 °C to 15 °C, whereas at 10 °C, cilia began to degenerate on the fourth day post-hatching, surviving for up to nine days. Interestingly, conditions of perpetual darkness led to increased egg production and survival rates compared to light exposure. Our findings provide critical insights into the adaptive responses of parasites to environmental changes and suggest that current deworming strategies may not adequately address the rapid hatching and increased egg production of M. sebastis. We emphasize the need for ongoing research to adapt aquaculture management strategies to the evolving challenges posed by parasites and recommend that future research focus on field studies examining the impact of environmental variables and multiple parasite species.

Identification of and Structural Insights into Hit Compounds Targeting N-Myristoyltransferase for Cryptosporidium Drug Development.

Each year, approximately 50,000 children under 5 die as a result of diarrhea caused by Cryptosporidium parvum, a protozoan parasite. There are currently no effective drugs or vaccines available to cure or prevent Cryptosporidium infection, and there are limited tools for identifying and validating targets for drug or vaccine development. We previously reported a high throughput screening (HTS) of a large compound library against Plasmodium N-myristoyltransferase (NMT), a validated drug target in multiple protozoan parasite species. To identify molecules that could be effective against Cryptosporidium, we counter-screened hits from the Plasmodium NMT HTS against Cryptosporidium NMT. We identified two potential hit compounds and validated them against CpNMT to determine if NMT might be an attractive drug target also for Cryptosporidium. We tested the compounds against Cryptosporidium using both cell-based and NMT enzymatic assays. We then determined the crystal structure of CpNMT bound to Myristoyl-Coenzyme A (MyrCoA) and structures of ternary complexes with MyrCoA and the hit compounds to identify the ligand binding modes. The binding site architectures display different conformational states in the presence of the two inhibitors and provide a basis for rational design of selective inhibitors.

A congeneric and non-randomly associated pair of larval trematodes dominates the assemblage of co-infecting parasites in fathead minnows (Pimephales promelas).

Individual hosts are often co-infected with multiple parasite species. Evidence from theoretical and empirical studies supports the idea that co-occurring parasites can impact each other and their hosts via synergistic or antagonistic interactions. The fundamental aim of understanding the consequences of co-infection to hosts and parasites requires an understanding of patterns of species co-occurrence within samples of hosts. We censused parasite assemblages in 755 adult, male fathead minnows collected from 7 lakes/ponds in southern Alberta, Canada between 2018 and 2020. Fifteen species of endoparasites infected fathead minnows, 98% of which were co-infected with between 2 and 9 parasite species (mean species richness: 4.4 ± 1.4). Non-random pairwise associations were detected within the overall parasite community. There were particularly strong, positive associations in the occurrences and intensities of the 2 congeneric larval trematodes Ornithodiplostomum sp. and Ornithodiplostomum ptychocheilus that comprised >96% of the 100 000+ parasites counted in the total sample of minnows. Furthermore, the occurrence of Ornithodiplostomum sp. was a strong predictor of the occurrence of O. ptychocheilus, and vice versa. Positive covariation in the intensities of these 2 dominants likely arises from their shared use of physid snails as first intermediate hosts in these waterbodies. These 2 species represent a predictable and non-random component within the complex assemblage of parasites of fathead minnows in this region.

Historical contingency in parasite community assembly: Community divergence results from early host exposure to symbionts and ecological drift.

Host individuals are commonly coinfected with multiple parasite species that may interact to shape within-host parasite community structure. In addition to within-host species interactions, parasite communities may also be structured by other processes like dispersal and ecological drift. The timing of dispersal (in particular, the temporal sequence in which parasite species infect a host individual) can alter within-host species interactions, setting the stage for historical contingency by priority effects, but how persistently such effects drive the trajectory of parasite community assembly is unclear, particularly under continued dispersal and ecological drift. We tested the role of species interactions under continued dispersal and ecological drift by simultaneously inoculating individual plants of tall fescue with a factorial combination of three symbionts (two foliar fungal parasites and a mutualistic endophyte), then deploying the plants in the field and tracking parasite communities as they assembled within host individuals. In the field, hosts were exposed to continued dispersal from a common pool of parasites, which should promote convergence in the structure of within-host parasite communities. Yet, analysis of parasite community trajectories found no signal of convergence. Instead, parasite community trajectories generally diverged from each other, and the magnitude of divergence depended on the initial composition of symbionts within each host, indicating historical contingency. Early in assembly, parasite communities also showed evidence of drift, revealing another source of among-host divergence in parasite community structure. Overall, these results show that both historical contingency and ecological drift contributed to divergence in parasite community assembly within hosts.

The overlooked complexity of avian brood parasite-host relationships.

The relationships between avian brood parasites and their hosts are widely recognised as model systems for studying coevolution. However, while most brood parasites are known to parasitise multiple species of host and hosts are often subject to parasitism by multiple brood parasite species, the examination of multispecies interactions remains rare. Here, we compile data on all known brood parasite–host relationships and find that complex brood parasite–host systems, where multiple species of brood parasites and hosts coexist and interact, are globally commonplace. By examining patterns of past research, we outline the disparity between patterns of network complexity and past research emphases and discuss factors that may be associated with these patterns. Drawing on insights gained from other systems that have embraced a multispecies framework, we highlight the potential benefits of considering brood parasite–host interactions as ecological networks and brood parasitism as a model system for studying multispecies interactions. Overall, our results provide new insights into the diversity of these relationships, highlight the stark mismatch between past research efforts and global patterns of network complexity, and draw attention to the opportunities that more complex arrangements offer for examining how species interactions shape global patterns of biodiversity.

Parasitism dramatically alters the ecosystem services provided by freshwater mussels

Abstract Parasites can indirectly affect ecosystem function by altering host phenotype, but the trait‐mediated impacts of parasitism at an ecosystem level remain poorly characterised. However, understanding the influence of parasites is central to understanding the ecosystem services provided by host species, especially in an era of global environmental change. We examined the effect of native (the trematode Rhipidocotyle campanula) and invasive (the bitterling fish Rhodeus amarus) parasites, and their interaction, on the clearance rates of unionid mussels, a dominant ecosystem‐engineering group that modify freshwater ecosystems worldwide. We used a combination of field experiments, laboratory experiments and ecological simulations to demonstrate the phenotypic impact of parasites on the functional response of two mussel species across an environmental gradient (suspended particle concentration), and extended this with host and parasite community data to demonstrate the consequences for a real‐world ecosystem, the Old West River in Cambridgeshire, England. Both parasites altered the clearance rates of their hosts but in contrasting fashion: while R. campanula increased host clearance rates relative to uninfected conspecifics under all conditions, R. amarus supressed clearance rates at high suspended particle concentrations (eutrophic conditions) but elevated them otherwise. The parasites displayed different infection patterns in the two host species, and the invasive R. amarus rarely co‐infected mussels with R. campanula. Given their disparate effects, the parasites' distributions reversed the relative filtration capacity of the two host species under high vs. low concentrations of suspended particles, demonstrating how differences between the infection patterns of native and invasive parasites, as well as their individual effects, need to be considered. Overall, the proportion of daily river discharge filtered by the combined mussel community changed by up to 96% in the presence of parasites. By incorporating multiple host species and multiple parasite species, we provide ecologically relevant evidence for the trait‐mediated effects of parasites on ecosystem processes. Our study demonstrates that parasitism can significantly alter wider ecosystem processes through changing the phenotype of their host. Future work on ecosystem function should take parasitism into account, and consider both trait‐mediated and density‐mediated effects. Read the free Plain Language Summary for this article on the Journal blog.

The use of a chimeric antigen for Plasmodium falciparum and P. vivax seroprevalence estimates from community surveys in Ethiopia and Costa Rica.

In low-transmission settings, accurate estimates of malaria transmission are needed to inform elimination targets. Detection of antimalarial antibodies provides exposure history, but previous studies have mainly relied on species-specific antigens. The use of chimeric antigens that include epitopes from multiple species of malaria parasites in population-based serological surveys could provide data for exposure to multiple Plasmodium species circulating in an area. Here, the utility of P. vivax/P. falciparum chimeric antigen for assessing serological responses was evaluated in Ethiopia, an endemic country for all four human malarias, and Costa Rica, where P. falciparum has been eliminated with reports of sporadic P. vivax cases. A multiplex bead-based assay was used to determine the seroprevalence of IgG antibodies against a chimeric malaria antigen (PvRMC-MSP1) from blood samples collected from household surveys in Ethiopia in 2015 (n = 7,077) and Costa Rica in 2015 (n = 851). Targets specific for P. falciparum (PfMSP1) and P. vivax (PvMSP1) were also included in the serological panel. Seroprevalence in the population and seroconversion rates were compared among the three IgG targets. Seroprevalence in Costa Rica was 3.6% for PfMSP1, 41.5% for PvMSP1 and 46.7% for PvRMC-MSP1. In Ethiopia, seroprevalence was 27.6% for PfMSP1, 21.4% for PvMSP1, and 32.6% for PvRMC-MSP1. IgG levels in seropositive individuals were consistently higher for PvRMC-MSP1 when compared to PvMSP1 in both studies. Seroconversion rates were 0.023 for PvMSP1 and 0.03 for PvRMC-MSP1 in Costa Rica. In Ethiopia, seroconversion rates were 0.050 for PfMSP1, 0.044 for PvMSP1 and 0.106 for PvRMC-MSP1. Our data indicate that chimeric antigen PvRMC-MSP1 is able to capture antibodies to multiple epitopes from both prior P. falciparum and P. vivax infections, and suitable chimeric antigens can be considered for use in serosurveys with appropriate validation.

Parasitic contamination of fresh vegetables sold in open markets: a public health threat

Abstract Vegetables eating raw are a leading source of transmission of infective forms of pathogenic internal parasites among human beings. This research was conducted from April to October, 2017 to assess the parasitic contamination of vegetables sold at main vegetable markets in districts Lower Dir and Peshawar, Pakistan. Eight hundred specimens of different vegetables were purchased and soaked in physiological saline solution, shaken with a mechanical shaker for 20 minutes and processed by sedimentation concentration method. Results revealed that only 19.7% (n=158/800) of the vegetables were found to be contaminated with single or multiple parasite species. Ascaris lumbricoides (the large round worm) 12.3% (n=99/800) was the most commonly detected pathogen and Taenia saginata (the beef tapeworm) 1.62% (n=13/800) was the least frequently detected one. Interestingly, significant p value (p>0.05 at 95%CI) between the number of examined and contaminated for all the variables studied including education status of the vendors, markets location, type of vegetables, means of display, washed before display, washing source of water and market type. The findings of this study evidenced that consumption of raw vegetables possesses great risk of getting parasitic infections in Lower Dir and Peshawar districts, Pakistan. Instructing the sellers and the public about parasitic disease transfer and their hygiene can reduce the infection rate of parasites of human origin.

Ectoparasitic fungi of Myrmica ants alter the success of parasitic butterflies

Exploitation of organisms by multiple parasite species is common in nature, but interactions among parasites have rarely been studied. Myrmica ants are rich in parasites. Among others, the ectoparasitic Rickia wasmannii fungus and the parasitic caterpillars of myrmecophilous Phengaris butterflies often infect the same Myrmica colonies. In this study, we examined the effects of R. wasmannii on the adoption, long-term development, and survival of P. alcon. In laboratory conditions, caterpillars introduced into nests of Myrmica scabrinodis uninfected with R. wasmannii survived significantly longer compared to caterpillars introduced into infected nests. In the field, joint infection was less common than expected if both parasites exploited M. scabrinodis colonies independently. Pre-pupal caterpillars of P. alcon were somewhat larger in nests infected with R. wasmannii than those found in uninfected nests. Based on these results it seems that R. wasmannii infection of M. scabrinodis affects the survival and development of P. alcon caterpillars, suggesting competition between these two ant parasites.