Mean Intensity Of Infection Research Articles

Universal versus taxon-specific drivers of helminth prevalence and intensity of infection.

Two key epidemiological parameters, prevalence and mean intensity of infection, together capture the abundance of macroparasite populations, the strength of density-dependent effects they experience, their potential impact on host population dynamics and the selective pressures they exert on their hosts. Yet, the drivers of the extensive variation observed in prevalence and mean intensity of infection, even among related parasite taxa infecting related hosts, remain mostly unknown. We performed phylogenetically grounded Bayesian modelling across hundreds of amphibian populations to test the effects of various predictors of prevalence and intensity of infection by six families of helminth parasites. We focused on the potential effects of key host traits and environmental factors pertinent to focal host populations, i.e. the local diversity of the amphibian community and local climatic variables. Our analyses revealed several important determinants of prevalence or intensity of infection in various parasite families, but none applying to all families. Our study uncovered no universal driver of parasite infection levels, even among parasite taxa from the same phylum, or with similar life cycles and transmission modes. Although local variables not considered here may have effects extending across taxa, our findings suggest the need for a taxon-specific approach in any attempt to predict disease dynamics and impacts in the face of environmental and climatic changes.

Diverse Relationships between Batrachochytrium Infections and Antimicrobial Peptide Defenses Across Leopard Frog Populations.

Antimicrobial peptides (AMPs) play a fundamental role in the innate defense against microbial pathogens, as well as other immune and non-immune functions. Their role in amphibian skin defense against the pathogenic fungus Batrachochytrium dendrobatidis (Bd) is exemplified by experiments in which depletion of host's stored AMPs increases mortality from infection. Yet, the question remains whether there are generalizable patterns of negative or positive correlations between stored AMP defenses and the probability of infection or infection intensity across populations and species. This study aims to expand on prior field studies of AMP quantities and compositions by correlating stored defenses with an estimated risk of Bd exposure (prevalence and mean infection intensity in each survey) in five locations across the United States and a total of three species. In all locations, known AMPs correlated with the ability of recovered secretions to inhibit Bd in vitro. We found that stored AMP defenses were generally unrelated to Bd infection except in one location where the relative intensity of known AMPs was lower in secretions from infected frogs. In all other locations, known AMP relative intensities were higher in infected frogs. Stored peptide quantity was either positively or negatively correlated with Bd exposure risk. Thus, future experiments coupled with organismal modeling can elucidate whether Bd infection affects secretion/synthesis and will provide insight into how to interpret amphibian ecoimmunology studies of AMPs. We also demonstrate that future AMP isolating and sequencing studies can focus efforts by correlating mass spectrometry peaks to inhibitory capacity using linear decomposition modeling.

Soil-transmitted helminth (STH) infections in the Wolaita zone in Southern Ethiopia: mid-stage evaluation of the Geshiyaro project and progress towards the interruption of transmission

BackgroundThis paper documents changes in the prevalence and intensity of soil-transmitted helminth (STH) infections in the Geshiyaro project in the Wolaita zone of Southern Ethiopia.MethodsThe Geshiyaro project comprises three intervention arms. Arm 1 is subdivided into the Arm 1 pilot (one district) and Arm 1 (four other districts), both receiving integrated community-wide mass drug administration MDA (cMDA) with intensive water, sanitation, and hygiene (WaSH) interventions. Arm 2 involves 18 districts with cMDA interventions plus the existing government-led One WaSH program, while Arm 3 serves as a control with school-based MDA (sMDA) interventions plus the existing government-led One WaSH program in three districts. The study is designed as a cohort investigation over time, with the establishment of longitudinal sentinel sites where infection levels are assessed annually. A total of 45 longitudinal parasitological surveillance sentinel sites are being used across all three intervention arms to monitor STH prevalence and intensity of infection. From each of the 45 sentinel sites, 150 individuals were randomly selected, stratified by age and gender. The t-test and analysis of variance (ANOVA) were employed to compare infection prevalence and intensity across the three study arms over time.ResultsThe prevalence of STH decreased significantly from 34.5% (30.6%, 38.5%) in 2019 to 10.6% (8.3%, 13.4%) in 2022/2023 (df = 1, P < 0.0001) in the Arm 1 pilot, from 27.4% (25.2%, 29.7%) in 2020 to 5.5% (4.4%, 6.7%) in 2023 (df = 1, P < 0.0001) in Arm 1, from 23% (21.3%, 24.8%) in 2020 to 4.5% (3.7%, 5.3%) in 2023 (df = 1, P < 0.001) in Arm 2, and from 49.6% (47.4%, 51.7%) in 2021 to 26.1% in 2023 (df = 1, P < 0.0001) in Arm 3. The relative reduction in the prevalence of any STH was the highest in the arms employing cMDA, namely Arm 2, with a decrease of 82.5% (79.3%, 84.2%), followed by Arm 1 with a reduction of 80.1% (75.3%, 84.6%), and then the Arm 1 pilot with a decrease of 69.4% (60.1%. 76.6%). Arm 3 employing sMDA had the lowest decrease, with a reduction of 46.9% (43.6%, 51%). The mean intensity of infection (based on Kato–Katz egg count measures) for Ascaris lumbricoides species, which was the dominant STH species present in the study area, decreased significantly in Arms 1 and 2, but only slightly in Arm 3. The prevalence of hookworm and Trichuris trichiura infections were found to be very low in all arms but also decreased significantly.ConclusionsThe reduction in the prevalence and intensity of STH in Arms 1 and 2 revealed steady progress towards transmission interruption based on cMDA intervention, but additional efforts with MDA coverage and WaSH interventions are needed to achieve a prevalence threshold < 2% based on the quantitative polymerase chain reaction (qPCR) diagnostic method.Graphical

Epidemiology of soil-transmitted helminthiasis among school-aged children in pastoralist communities of Kenya: A cross-sectional study.

Soil-transmitted helminthiasis (STH) are a major public health problem in Sub-Saharan Africa. In Kenya, the National School Based Deworming Program (NSBDP) was launched in 2012 with a goal of reducing STH prevalence in school-aged children (SAC) to <1%, however monitoring and evaluation results have consistently showed > 20% prevalence in Narok County. We conducted a study to investigate factors associated with STH infections among SAC in Narok County. A cross-sectional study was conducted among 514 SAC from five schools in Trans Mara West sub-county, Narok County. The sub-county was selected because it had participating schools within the NSBDP with a high prevalence of STH infection. Participants were selected using systematic random sampling. Stool samples collected from participants were examined for STH eggs using Kato-Katz technique. An open data kit questionnaire was used to collect socio-demographics, household, and STH knowledge information from 139 of the 514 SAC. Descriptive statistics was used to summarize the data, prevalence and mean intensity of infections were calculated, and logistic regression used to determine factors associated with STH infections. The overall prevalence of any STH infection was 24.6% (95%CI: 21.1-28.6). Trichuris trichiura 14.4% (95%CI: 11.7-17.8), Ascaris lumbricoides 12.5% (95%CI: 9.9-15.7) and hookworm 0%. From multivariable analysis the only factors significantly associated with increased risk of STH infection were, children attending Karda and Nkarano schools with aOR = 5.29 (95%CI: 1.45-19.24); p = 0.011 and aOR = 4.53 (95%CI: 1.29-15.97); p = 0.019 respectively. For A. lumbricoides, children attending Nkarano School were associated with a significant risk of infection with aOR = 7.81 (95%CI: 1.81-33.63); p = 0.006. Despite the ongoing work of NSBDP, the STH prevalence is still ≥ 20% in Trans Mara West sub-county Narok County, among SAC. This underscores the need for continued annual MDA. Additionally, if possible, drug combinations may effectively manage T. trichiura, the region's most common helminth. The study found a correlation between children attending specific schools and STH infection risk, suggesting the importance of health education and improved water, sanitation, and hygiene practices holistically both in schools and associated catchment areas that can act as STH reservoirs to alleviate the burden of STH.

Investigation of Anisakis infections in coastal marine fishes and awareness of anisakiasis control knowledge among residents in Yantai City in 2021

To investigate the prevalence of Anisakis infections in coastal marine fishes and awareness of anisakiasis control knowledge among local residents in Yantai City, Shandong Province in 2021, so as to provide insights into formulation of anisakiasis control interventions. Marine fishes were purchased from Shunxin Port, Yantai City, Shandong Province in November 2021, and the presence of Anisakis was detected in different species of fishes and different fish sites. The correlations between body length and weight of marine fish and intensity of Anisakis infections were examined using Spearman's rank correlation analysis, and the dietary habits and anisakiasis control knowledge were investigated using questionnaire surveys among local residents. A total of 201 marine fishes belonging to 20 species were dissected, and Anisakis was detected in 77 marine fishes (38.31%) belonging to 11 species (55.00%), with a mean infection intensity of 45.04 parasites per fish (3 468/77). Spearman's rank correlation analysis revealed that the body length (rs = 0.74, P < 0.05) and weight (rs = 0.79, P < 0.01) of the monkfish correlated positively with the intensity of Anisakis infections, and the body length (rs = 0.68, P < 0.05) of the flatfish correlated positively with the intensity of Anisakis infections, while no correlations were examined between the body length or weight of other marine fishes and the intensity of Anisakis infections. Of all respondents, 53.38% men and 56.67% women did not know anisakiasis control knowledge at all, and there was a significant difference in the proportion of respondents using separate chopping boards for raw and cooked food from different villages (χ2 = 17.89, P < 0.01), while there was an age-specific proportion of respondents with habitats of eating raw or semi-raw seafood (χ2 = 28.27, P < 0.01). The prevalence and intensity of Anisakis infections were high in coastal marine fishes in Yantai City in 2021, and the awareness of anisakiasis control knowledge was low among local residents. Intensified health education pertaining to anisakiasis control knowledge is recommended to reduce the risk of Anisakis infections.

Progress in controlling the transmission of schistosome parasites in Southern Ethiopia: the Geshiyaro Project in the Wolaita Zone

BackgroundThis paper describes changes in the prevalence and intensity of schistosome parasite infections in a project integrating mass drug administration (MDA), water, sanitation, and hygiene (WaSH), and behavioral change interventions.MethodsThe Geshiyaro Project comprises three intervention arms. Arm 1 is subdivided into “Arm 1 pilot” (one district) and Arm 1 (four other districts), both receiving integrated community-wide MDA with intensive WaSH interventions. Arm 2 involves 17 districts with community-wide MDA interventions, while Arm 3 serves as a control with school-based MDA interventions in three districts. A total of 150 individuals, stratified by age group, were randomly selected from each of the 45 sentinel sites. Arm sizes were 584 (Arm 1 pilot), 1636 (Arm 1), 2203 (Arm 2), and 2238 (Arm 3). Statistical tests were employed to compare infection prevalence and intensity across the different arms.ResultsThe prevalence of schistosome parasite infection ranged from 0% to 2.6% and from 1.7% to 25.7% across districts, employing the Kato-Katz (KK) and point-of-care circulating cathodic antigen (POC-CCA) diagnostics, respectively. The mean infection intensity level showed no marked difference between baseline and follow-up surveys when measured by KK, except in Arm 2 (t = 6.89, P < 0.0001). Infection prevalence decreased significantly in Arm 1 (t = 8.62, P < 0.0001), Arm 2 (t = 6.94, P < 0.0001), and Arm 3 (t = 8.83, P < 0.0001), but not in Arm 1 pilot (t = 1.69, P = 0.09) by POC-CCA, when trace was considered positive. The decrease was significant only in Arm 1 (t = 3.28, P = 0.0001) and Arm 2 (t = 7.62, P < 0.0001) when the trace was considered negative in POC-CCA. Arm 2 demonstrated a significant difference in difference (DID) compared to the control group, Arm 3, regardless of whether trace in POC-CCA was considered positive (DID = 3.9%, df = 8780, P = 0.025) or negative (DID = −5.2, df = 8780, P = 0.0004).ConclusionsThe prevalence of schistosomiasis was low when employing the KK diagnostic but moderate in some locations by the POC-CCA diagnostic. The infection level had decreased across all arms of the Geshiyaro study at mid-term of the 7-year project, but further efforts are needed to reduce the rate of parasite transmission based on the POC-CCA diagnostic scores.Graphical

Accuracy and precision of dried urine spot method for the detection of Schistosoma mansoni circulating cathodic antigens in resource-limited settings

BackgroundThe World Health Organization recommends the use of Schisto point-of-care circulating cathodic antigens (Schisto POC-CCA) for screening of Schistosoma mansoni as it offers better sensitivity than microscopy. However, there are limitation facing the use of this method including timely availability of the test cassettes. The aim of this study was to determine the reliability of dried urine spot (DUS) method for collection of urine and detection of S. mansoni using Schisto POC-CCA cassettes in a resource-limited settings.MethodsA cross-sectional study was conducted between October and November 2022 among 250 primary school children in Sengerema District, northwestern Tanzania. S. mansoni CCA was detected in filter paper-based DUS, liquid urine using DUS Schisto POC-CCA (index), and direct urine Schisto POC-CCA (comparator) methods respectively. S. mansoni eggs in stool were detected using duplicate Kato-Katz (KK) method. The measures of accuracy were computed and compared between the index and comparator methods. The strength of agreement between inter-raters precisions was tested using Cohen’s kappa (k).ResultsThis study revealed S. mansoni prevalence rates of 28.8%, 54.0% and 50.8% by duplicate KK, direct urine Schisto POC-CCA and DUS Schisto POC-CCA methods respectively. The mean intensity of infection among infected participants was 86.3 eggs per gram of stool (EPG) ranging from 12.0 EPG to 824.0 EPG. The sensitivity of DUS Schisto POC-CCA and direct urine Schisto POC-CCA was 94.44% (95% CI: 89.15–99.74%) and 97.22% (95% CI: 93.43–100.00%) respectively. The DUS Schisto POC-CCA method had slightly higher specificity (66.85%) than direct urine Schisto POC-CCA method (63.48%). The accuracy of the DUS Schisto POC-CCA was found to be slightly high (74.80%, 95% CI: 68.94–79.06%) compared to that of direct urine Schisto POC-CCA (73.20%, 95% CI: 67.25–78.59%). There was good agreement between two laboratory technologists who performed the DUS Schisto POC-CCA method on similar samples (k = 0.80, 95% CI: 0.59–0.95).ConclusionsThe DUS Schisto POC-CCA method had comparable S. mansoni detection accuracy to direct urine Schisto POC-CCA. This suggests that the method could be a potential alternative to direct urine Schisto POC-CCA for screening S. mansoni in resource-limited situations.Graphical

Centrorhynchus spp. (Acanthocephala) in South America: new anuran record and checklist of vertebrate hosts.

The aim of this study was to record Centrorhynchus sp. associated with the exotic species Aquarana catesbeiana (bullfrog) in southern Brazil and to present a checklist of vertebrate hosts in South America. Twenty-nine adults and juveniles of A. catesbeiana were collected in Capão do Leão, state of Rio Grande do Sul, Brazil, between October 2019 and December 2020. We found 275 specimens of Centrorhynchus sp. cystacanths in the stomach musculature and coelomic cavity of 55.1% of hosts (16). There was no significant differences in the prevalence and mean intensity of infection with cystacanths when compared males and females of A. catesbeiana. The prevalence was significantly higher in adults than in juveniles. The checklist presents 106 species of vertebrate hosts and 14 taxa of Centrorhynchus recorded in nine South American countries. Avian were the main definitive hosts of Centrorhynchus spp. and snakes Dipsadidae, anurans Hylidae and Leptodactylidae the main paratenic hosts in South America. This is the first record of Centrorhynchus cystacanths in A. catesbeiana in the South America. The study provides tools to help understand the parasitic relationships between species of Centrorhynchus and A. catesbeiana and other hosts in areas where bullfrog have been introduced.

The first record of ostrich feather louse (Struthiolipeurus struthionis) collected from farmed ostriches (Struthio camelus) in the United Arab Emirates.

Ostrich (Struthio camelus) farming in the United Arab Emirates (UAE) is a relatively new field of farming. Farmed ostriches are susceptible to ectoparasite infestation, which affects their production. This study was conducted to estimate the prevalence of ectoparasites on ostriches raised on a farm in Abu Dhabi Emirate. The feathers of 42 ostriches (26 females and 16 males) were collected and morphologically examined for ectoparasites. In total, 283 lice (89 males and 194 females) were collected from birds. However, there were no ticks or other ectoparasites. Lice were preserved in 1.5 mL tubes containing 70% ethanol and were later identified using taxonomic keys. The prevalence, mean intensity of infection, and mean abundance were estimated. One louse species, Struthiolipeurus struthionis was identified. To the best of our knowledge, this is the first report of S. struthionis in ostriches raised in the UAE with an overall prevalence of 88%. The prevalence of lice was significantly higher in July (100%) than that in May (66.7%). Likewise, the mean intensity and abundance of lice were significantly higher in June (10.6 and 9.94, respectively) than in May (3.25 and 2.2, respectively). The high prevalence of lice poses a serious risk to ostrich farming by negatively affecting the health and productivity of ostriches.

Parasitos de peixes de um rio costeiro neotropical dentro de um hotspot de biodiversidade

Abstract: Aim We investigated the ichthyofauna parasite component community across a gradient of anthropogenic pressures of the Guaraguaçu River, south Brazil, a Neotropical river of central importance for biodiversity conservation. Methods After fish sampling, all fish were identified, measured, weighed and eviscerated. The viscera and gills were inspected for parasite screening and subsequent identification. Parasite diversity estimators were calculated for the most abundant host species. Results A total of 159 host specimens from 12 species were examined, being 140 (88.05%) found to be infected with at least one parasite, including 14 new parasite occurrences. The most widely distributed parasite was the nematode Contracaecum sp., found in 8 host species. The highest mean infection intensity and mean abundance was observed for the monogenean Aphanoblastella mastigatus, infecting the Silver catfish Rhamdia quelen. The Shannon-Wiener, Jost and Simpson indexes were higher for the more abundant fishes, except for the Trahira Hoplias malabaricus. Most host species harbored parasites in poorly aggregated distribution, according to the discrepancy index. The Berger-Parker index showed monogenean dominance in all hosts except for H. malabaricus. We found little evidence for parasite infracommunity changes across the gradient of the river. Conclusions We described the infection patterns in an important Neotropical river. The new parasite occurrences highlight the contribution of our study. Fish-parasite interactions changed throughout the river stretches, and we argue that it does not necessarily means changes in diversity and abundance of parasite within species, but the rearrange of interactions. Moreover, it seems that parasites are more abundant in most impacted sites, another reason to continue the monitoring.

Intestinal helminthic parasites in Columba livia (Columbiformes: Columbidae) in southern Brazil: do seasons influence helminth infections in the Neotropical region?

Objective: The aim of this study was to analyze intestinal helminthic infections in pigeons Columba livia Gmelin, 1789 (Columbiformes: Columbidae) which were collected in three different seasons in southern Brazil. Material and methods: Ninety birds (hosts) were captured in the urban area in Pelotas, Rio Grande do Sul (RS) state, Brazil, in autumn, winter and spring in 2018 and 2019. Results: Helminths species and their prevalences were: Ascaridia columbae (33.33%), Baruscapillaria obsignata (23.33%) (Nematoda), Brachylaima mazzantii (3.33%) (Digenea), Skrjabinia sp. (11.11%) and Killigrewia sp. (3.33%) (Cestoda). Prevalence and mean intensity of infection in the three collection periods did not show any significant difference, except A. columbae, which was more prevalent in autumn than in spring. Conclusion: Results showed that abiotic and environmental conditions found in the region were suitable for the development of intestinal helminths associated with C. livia in the sampling periods in southern Brazil.

Türkiye'nin endemik balıklarından Capoeta aydinensis' ten Paradiplozoon bliccae (Reichenbach-Klinke, 1961) (Monogenea: Diplozoidae)'nin ekolojik, moleküler ve konak ilişkili faktör yaklaşımıyla araştırmalar

The present study investigated diplozoid parasites in an endemic species, Capoeta aydinensis Turan, Küçük, Kaya, Güçlü &amp; Bektaş, 2017 in Köyceğiz Lake, near Muğla province (Türkiye). The aim of this research is to improve a record of diplozoid species occurrence in C. aydinensis, an endemic fish species by collecting data from a previously unexplored locality situated in a different geographical region of Türkiye. A total of 187 individuals of C. aydinensis were collected by using fishing nets from October 2019 to July 2020 and examined for the presence of diplozoid species. Only one species of diplozoid has been recorded, known as Paradiplozoon bliccae (Reichenbach-Klinke, 1961), which has been identified morphologically and confirmed through molecular analysis. The nucleotide sequences of the parasite's nuclear internal transcribed spacer (ITS2) gene marker were determined as well as phylogenetic analyses by using Bayesian inference (BI) analyses. On the basis of the molecular findings, the morphological identification of the diplozoid parasite species was confirmed. Of 187 fish sampled, 27 were infected with 117 P. bliccae, representing an abundance of 0.6, a mean intensity of 4.3 and a prevalence of 14.4%. The prevalence and mean intensity of infection were based on the season and sex of the host. The highest values of infection for prevalence, mean intensity and abundance were found in summer. Meanwhile, mean intensity and abundance of P. bliccae were higher in males, the prevalence was higher in females. To our knowledge, the present study is the first ichthyoparasitological study of C. aydinensis in Köyceğiz lake, near the province of Muğla in Türkiye. Furthermore, sequence data of P. bliccae from fish hosts in this locality were reported to GenBank for the first time as part of this study. Therefore, this study widens the host range of this parasite species in Türkiye.

Developing low-cost house floors to control tungiasis in Kenya – a feasibility study

ContextTungiasis is a neglected tropical skin disease endemic in resource-poor communities. It is caused by the penetration of the female sand flea, Tunga penetrans, into the skin causing immense pain, itching, difficulty walking, sleeping and concentrating on school or work. Infection is associated with living in a house with unsealed earthen house floors.MethodsThis feasibility study used a community-based co-creation approach to develop and test simple, locally appropriate, and affordable flooring solutions to create a sealed, washable floor for the prevention of tungiasis. Locally used techniques were explored and compared in small slab trials. The floor with best strength and lowest cost was pilot trialed in 12 households with tungiasis cases to assess its durability and costs, feasibility of installation in existing local houses using local masons and explore community perceptions. Disease outcomes were measured to estimate potential impact.ResultsIt was feasible to build the capacity of a community-based organization to conduct research, develop a low-cost floor and conduct a pilot trial. The optimal low-cost floor was stabilized local subsoil with cement at a 1:9 ratio, installed as a 5 cm depth slab. A sealed floor was associated with a lower mean infection intensity among infected children than in control households (aIRR 0.53, 95%CI 0.29–0.97) when adjusted for covariates. The cost of the new floor was US$3/m2 compared to $10 for a concrete floor. Beneficiaries reported the floor made their lives much easier, enabled them to keep clean and children to do their schoolwork and eat while sitting on the floor. Challenges encountered indicate future studies would need intensive mentoring of masons to ensure the floor is properly installed and households supervised to ensure the floor is properly cured.ConclusionThis study provided promising evidence that retrofitting simple cement-stabilised soil floors with locally available materials is a feasible option for tungiasis control and can be implemented through training of community-based organisations. Disease outcome data is promising and suggests that a definitive trial is warranted. Data generated will inform the design of a fully powered randomized trial combined with behaviour change communications.Trial registrationISRCTN 62801024 (retrospective 07.07.2023).

Sequence analysis of Paragonimus internal transcribed spacer 2 and cyclooxygenase 1 genes in freshwater crabs in Henan Province

To investigate the sequences of internal transcribed spacer 2 (ITS2) and cyclooxygenase 1 (COX1) genes of Paragonimus metacercariae in freshwater crabs in Henan Province, identify the species of Paragonimus and evaluate its genetic relationships with Paragonimus isolates from other provinces in China. Freshwater crabs were collected from 8 survey sites in Zhengzhou, Luoyang, Pingdingshan, Nanyang and Jiyuan cities of Henan Province from 2016 to 2021, and Paragonimus metacercariae were detected in freshwater crabs. Genomic DNA was extracted from Paragonimus metacercariae, and the ITS2 and COX1 genes were amplified using PCR assay, followed by sequencing of PCR amplification products. The gene sequences were spliced and aligned using the software DNASTAR, and aligned with the sequences of Paragonimus genes in the GenBank. Phylogenetic trees were created using the MEGA6 software with the Neighbor-Joining method based on ITS2 and COX1 gene sequences, with Fasciola hepatica as the outgroup. The detection rates of Paragonimus metacercariae were 6.83% (11/161), 50.82% (31/61), 18.52% (5/26), 8.76% (12/137), 14.29% (9/63), 17.76% (19/105), 18.50% (32/173) and 42.71% (41/96) in freshwater crabs from 8 survey sites in Zhengzhou, Luoyang, Pingdingshan, Nanyang and Jiyuan cities of Henan Province, with a mean detection rate of 19.46% (160/822), and a mean infection intensity of 0.57 metacercariae/g. The amplified ITS2 and COX1 gene fragments of Paragonimus were approximately 500 bp and 450 bp in lengths, respectively. The ITS2 gene sequences of Paragonimus metacercariae from 8 survey sites of Henan Province showed the highest homology (99.8% to 100.0%) with the gene sequence of P. skrjabini (GenBank accession number: MW960209.1), and phylogenetic analysis showed that the Paragonimus in this study was clustered into the same clade with P. skrjabini from Sichuan Province (GenBank accession number: AY618747.1), Guangxi Zhuang Autonomous Region (GenBank accession number: AY618729.1) and Hubei Province (GenBank accession number: AY618751.1), and P. miyazaki from Fujian Province (GenBank accession number: AY618741.1) and Japan (GenBank accession number: AB713405.1). The COX1 gene sequences of Paragonimus metacercariae from 8 survey sites of Henan Province showed the highest homology (90.0% to 100.0%) with the gene sequence of P. skrjabini (GenBank accession number: AY618798.1), and phylogenetic analysis showed that the Paragonimus in this study was clustered into the same clade with all P. skrjabini and clustered into the same sub-clade with P. skrjabini from Hubei Province (GenBank accession numbers: AY618782.1 and AY618764.1). Paragonimus species from freshwater crabs in Henan Province were all characterized as P. skrjabini, and the ITS2 and COX1 gene sequences had the highest homology to those of P. skrjabini from Hubei Province. The results provide insights into study of Paragonimus in Henan Province and China.

Associations of Batrachochytrium dendrobatidis with skin bacteria and fungi on Asian amphibian hosts

Amphibian skin harbors microorganisms that are associated with the fungal pathogen Batrachochytrium dendrobatidis (Bd), which causes chytridiomycosis, one of the most significant wildlife diseases known. This pathogen originated in Asia, where diverse Bd lineages exist; hence, native amphibian hosts have co-existed with Bd over long time periods. Determining the nuances of this co-existence is crucial for understanding the prevalence and spread of Bd from a microbial context. However, associations of Bd with the natural skin microbiome remain poorly understood for Asian hosts, especially in relation to skin-associated fungi. We used 16 S rRNA and fungal internal transcribed spacer (ITS) gene sequencing to characterize the skin microbiome of four native Asian amphibian species and examined the relationships between Bd infection and their skin bacterial and fungal communities; we also analyzed the correlates of the putative anti-Bd bacteria. We show that both skin bacterial and fungal community structure and composition had significant associations with infection status (Bd presence/absence) and infection intensity (frequency of Bd sequence reads). We also found that the putative anti-Bd bacterial richness was correlated with Bd infection status and infection intensity, and observed that the relative abundance of anti-Bd bacteria roughly correspond with changes in both Bd prevalence and mean infection intensity in populations. Additionally, the microbial co-occurrence network of infected frogs was significantly different from that of uninfected frogs that were characterized by more keystone nodes (connectors) and larger proportions in correlations between bacteria, suggesting stronger inter-module bacterial interactions. These results indicate that the mutual effects between Bd and skin-associated microbiome, including the interplay between bacteria and fungi, might vary with Bd infection in susceptible amphibian species. This knowledge will help in understanding the dynamics of Bd from a microbial perspective, potentially contributing to mitigate chytridiomycosis in other regions of the world.

Prevalence of Foodborne Trematodes in Small Indigenous Fish Species in Local Markets of Phnom Penh, Cambodia.

Background: This study aimed to determine the prevalence and mean infection intensity of zoonotic foodborne trematodes (FBT) in small indigenous species (SIS) fish hosts. Materials and Methods: A total of 8630 specimens of unknown origin were collected from the markets in Phnom Penh City. Fish were identified, weighed, and separated into 20 g subsamples for each fish species, and were examined using the artificial digestion method. A total of 10 species of FBT were detected in 11 species of fish out of the 23 species of fish in the total sample. Results: All infected FBT species were intestinal flukes. No liver flukes were found. The overall prevalence of FBT infection was 29.3% ± 5.3%, and the mean intensity was 0.85 ± 1.89 metacercariae (Mc)/g. The highest FBT prevalence was observed for Isthmiophora hortensis (10.7%) and Centrocestus formosanus (7.9%). Other species identified were Diplostomum spp., Echinochasmus japonicus, Echinostoma revolutum, Echinostoma sudanense, Haplorchis taichui, Haplorchis pumilio Heterophyes spp., and Procerovum varium. The highest mean intensity was found for Diplostomum spp. (1.75 ± 3.03 Mc/g). Trichopsis vittata was one of the main species constituting the SIS in urban markets (31.72%) and showed the highest prevalence of FBT (75.0%). In addition, T. vittata had the highest diversity of intestinal flukes compared with other fish species. Amblypharyngodon chulabhornae showed the highest mean intensity. but low diversity (only two species) and low prevalence. Conclusions: T. vittata could be considered a potential indicator for targeted monitoring of FBT intestinal flukes, but A. chulabhornae could also be considered for quantitative studies considering its high mean intensity.

Parasite-host relations and new reports of helminths for Rhinella dorbignyi (Duméril &amp; Bibron, 1841) (Anura: Bufonidae) from Neotropical region

This study aimed to analyze helminth assemblage in Rhinella dorbignyi regarding host gender, size and mass in two sampling sites in southern Brazil, and to report new parasite associations. Anurans (n = 100) were collected in two localities from Rio Grande do Sul (RS) state, Brazil, from 2017 to 2020. Nineteen taxa (adults and larval forms) belonging to Nematoda, Acanthocephala, Digenea, and Cestoda were found in different infection sites. Cosmocercidae gen. Spp., Physaloptera liophis, Catadiscus sp., and Cylindrotaenia americana were the dominant taxa in helminth assemblage. Female anurans showed higher helminth species richness than males considering the total sample (two localities) or one of the two localities. However, prevalence and mean intensity of infection did not show any significant difference between genders. Mean intensity of infection was significantly higher (19.52) in Laranjal locality. Host body size does not influence helminth abundance, as infections did not show significant correlation snout-vent length (SVL) nor body mass (BM) of anurans. The findings reveal anurans of R. dorbignyi may be intermediate, paratenic and definitive host for these parasites. Plagiorchioidea helminths (Digenea), Physaloptera liophis, larvae of Acuariidae and Spiroxys sp. (Nematoda), and cystacanth of Lueheia sp. (Acanthocephala) constitute new records for R. dorbignyi. Additionally, this is the first record of Cylindrotaenia americana larvae in this host species. Resulting information increases the knowledge on biodiversity and parasite-host relations and may help future conservation programs developed in ecosystems in the extreme south of Brazil.

Metazoan parasites of the Ocellated killifish, Floridichthys polyommus (Cyprinodontidae) in La Carbonera coastal lagoon, Yucatán, Mexico

The Ocellated killifish or “bolín yucateco”, Floridichthys polyommus, is an endemic resident of the Yucatan Peninsula, Mexico; it tolerates hypersaline and oligohaline conditions and is considered the dominant species in these ecosystems. In this study, we analyzed 108 individuals of F. polyommus between 2019 and 2013 from La Carbonera coastal lagoon, northern Yucatán Peninsula. We report the taxonomic composition of their metazoan parasite fauna at the infracommunity (individual hosts) and component community (whole sample) levels, estimating parasite community attributes such as species richness, abundance, and diversity. Fish individuals were measured, dissected, and examined for ecto and endoparasites. Metazoan parasites were identified using morphological and molecular data. Sixteen parasite taxa were found, including six digeneans, three nematodes, and one of the following: cestode, acanthocephalan, copepod, isopod, argulid, hirudinean, and pentastomid. Ten of them were found as larval stages. The prevalence and mean intensity of infection were calculated for each parasite taxon. The cestode Glossocercus caribaensis was the most prevalent taxon, whereas the digenean Ascocotyle sp.1 was the most abundant. For ecological analyses, three species of Contracaecum were lumped together. The species richness and diversity of the component community were 14 and 0.049, respectively, whereas at the infracommunity level, both parameters were 1.9 ± 1.27 and 0.147 ± 0.225. The parasite species richness values in F. polyommus at both levels were higher than those previously reported in other species of Cyprinodontidae. We discuss that the parasite community of F. polyommus reflect its importance in energy transport in coastal lagoons of the Yucatán Peninsula.

Infection with swim bladder nematode Anguillicola crassus in relation to European eel growth, age, and habitat along the German Baltic coast.

One possible reason for the European eel (Anguilla anguilla) population decline is the neozoan eel swim bladder nematode Anguillicola crassus. To investigate whether the prevalence of A. crassus and the associated swim bladder pathology is related to eel habitat, growth rate, and age, 728 yellow eels from 6 habitats differing in salinity and located along the German Baltic coast were examined between 2005 and 2009. The prevalence of A. crassus varied between habitats, ranging from 9 to 57%. Infection prevalence and the percentage of eels with a damaged swim bladder were significantly higher in inner coastal waters compared to more saline open coastal water. In infected eels, 1 to 32 adult and preadult individuals of A. crassus were observed. The mean infection intensity varied between habitats from 2 to 7 nematodes per eel but did not significantly differ between inner and open coastal waters. Infection prevalence and intensity decreased significantly with age when all open coastal waters and all habitats were combined. Both the lower prevalence of A. crassus and the swim bladder damage of older eels and of eels originating from open coastal water habitats suggest that these eels have a higher fitness for spawning migrations than eels from inner coastal waters. The present study underlines the importance of eel screening on a sufficiently small geographical scale for the accurate estimation of eel recruitment and the identification of priority areas that are likely to produce healthy silver eels.

Infection levels of Gnathostomatidae (Nematoda) larvae in commercial fishes in north-eastern Australian waters and related food safety concerns

The majority of research on the safety of marine edible fish has primarily focused on anisakid nematodes, neglecting the potential risks posed by other parasites, including those belonging to the family Gnathostomatidae. In Australia, there have been few reported cases of human infections with gnathostomatid parasites since 2011. However, due to the absence of a standardized diagnostic test in the country, it is believed that the actual number of infections is higher than reported. This study aimed to assess the occurrence and prevalence of infectious gnathostomatid parasites in selected commercial fish species in Australia. A total of 1947 marine fish from northern Australia, representing 9 families, 16 genera, and 30 species, were examined for gnathostomatid nematode infections. Overall, 12.3 % of the fish were found to be infected with at least one gnathostomatid larva. Among the species examined, the yellow-dabbled flounder (Branchypleura novaezeelandiae) exhibited the highest prevalence (83.3 %; n = 6) and the largest number of gnathostomatid larvae. The identification of the gnathostomatid larvae was confirmed as belonging to the genus Echinocephalus based on both morphological characteristics and sequence data. No significant correlation was observed between the prevalence, mean abundance, and mean intensity of infection with the length or weight of the examined fish species. Notably, several of the infected fish species are considered popular choices in the Australian market. Hence, it is imperative to raise awareness among relevant food safety authorities regarding the occurrence of these parasites. The findings from this study should be taken into consideration for the revision of current seafood safety protocols in the country.