High Intensity Of Infection Research Articles

Effects of Trematode Parasites on Snails and Northern Leopard Frogs (Lithobates pipiens) in Pesticide-Exposed Mesocosm Communities

Chemical contamination of aquatic environments is widespread, but we have a limited understanding of how contaminants alter critical host–parasite interactions that can influence disease dynamics. We manipulated Northern Leopard Frog (Lithobates pipiens) exposure to pesticides (no pesticides, the insecticide Bacillus thuringiensis israelensis [Bti], or the herbicide atrazine) and trematode-infected (Ribeiroia ondatrae and Echinostoma spp.) snails in outdoor mesocosms. Bti exposure extended host larval period, and atrazine exposure had a nonsignificant trend toward reducing host survival; however, neither pesticide influenced parasite success nor magnified the effects of parasites on their hosts. Parasites negatively influenced tadpole development and, by metamorphosis, parasitized frogs had severe limb deformities and greater mass than unparasitized frogs. The greater mass in parasitized frogs may have resulted from reduced competition between tadpoles and snails for algal resources because parasites decreased snail abundance in mesocosms. Reduced competition between tadpoles and snails may offset the direct negative effects of trematodes on tadpoles, enabling them to survive with high infection intensities. Trematodes may further facilitate their own success by inducing limb deformities that likely increase anuran consumption by definitive hosts. Our results demonstrate how common pesticides and parasites impact amphibians and suggest that, at environmentally relevant concentrations, these pesticides may not dramatically alter host–parasite dynamics.

Prevalence of urogenital and intestinal schistosomiasis among school children in South-west Nigeria.

The risk of co-infection with Schistosoma haematobium and S. mansoni and the potential harmful effect on morbidity and control is enhanced by the overlapping distribution of both species in sub-Saharan Africa. Despite the reported high endemicity of both species in Nigeria, studies on the spread and effect of their mixed infection are limited. Therefore, a cross-sectional survey was conducted among school children in two communities in South-west Nigeria to investigate the prevalence of mixed human schistosome infection, intensity, and possible ectopic egg elimination. Urine and stool samples were collected from consenting school children in Ilie and Ore communities of Osun State, Nigeria. Schistosoma haematobium eggs were detected in urine using the urine filtration technique, while S. mansoni eggs were detected in stool using the Kato-Katz thick smear technique. The study enrolled 466 primary and secondary school children (211; 45.3% males vs. 255; 54.7% females; mean age 11.6 ± 3.16 years). The overall prevalence of schistosomiasis was 40% (185/466), with 19% (89/466) recording single S. haematobium infection while 9% (41/465) had a single S. mansoni infection. The geometric mean egg count for S. haematobium was 189.4 egg/10ml urine; 95% CI: range 115.9-262.9, while for S. mansoni, it was 115.7 epg; 95% CI: range 78.4-152.9. The prevalence of ectopic S mansoni (S. mansoni eggs in urine) was 4.7%, while no ectopic S. haematobium (S. haematobium eggs in stool) was recorded. Mixed infection of S. haematobium/S. mansoni had a prevalence of 9.5% (44/466). More females (54.5%) presented with S. haematobium/S. mansoni co-infection. For both parasites, males had higher infection intensity, with a significant difference observed with S. haematobium (p = 0.0004). Hematuria was significant in individuals with single S. haematobium infection (p = 0.002), mixed ectopic S. haematobium/S. mansoni (p = 0.009) and mixed S. haematobium/S. mansoni/ectopic S. mansoni (p = 0.0003). These findings suggest the probability of interspecific interactions between S. haematobium and S. mansoni. Scaling up of mass administration of praziquantel and control measures in the study areas is highly desirable.

Big bees spread disease: body size mediates transmission of a bumble bee pathogen.

Trait variation can have important consequences for the outcomes of species interactions. Even though some traits vary as much within species as across related species, models and empirical studies typically do not consider the role of intraspecific trait variation for processes such as disease transmission. For example, many pollinator species are in decline because of a variety of stressors including pathogens, but the role of intraspecific trait variation in mediating disease dynamics is rarely considered. For example, pollinator body size could affect pathogen transmission via differences in resistance, foraging behavior and physiology. We tested effects of body size on pollinator pathogen transmission using the common eastern bumble bee Bombus impatiens in field tents, introducing an infected "donor" microcolony of large or small workers with an uninfected average-sized "recipient" microcolony and allowing bees to forage for 9-16d. Small donor bees had nearly 50% higher infection intensity (cells/0.02 μL) than large donor bees, but large donor bees were twice as likely to transmit Crithidia bombi to recipient bees. Both behavioral and physiological mechanisms may underlie this apparent paradox. Compared to small bees, large bees foraged more and produced more feces; simulations showed that foraging and defecation rates together had stronger effects on transmission than did donor infection intensity. Thus, effects of bee size on contact rates and pathogen supply may play significant roles in disease transmission, demonstrating the multifaceted impacts of traits on transmission dynamics.

Exposure to Batrachochytrium dendrobatidis affects chemical defences in two anuran amphibians, Rana dalmatina and Bufo bufo

BackgroundBatrachochytrium dendrobatidis (Bd) is the causative agent of chytridiomycosis, one of the major causes of worldwide amphibian biodiversity loss. Many amphibians exhibit skin-based chemical defences, which may play an important role against invading pathogens, but whether the synthesis of these chemical compounds is enhanced or suppressed in the presence of pathogens is largely unknown. Here we investigated direct and indirect effects of larval exposure to the globally distributed and highly virulent Bd-GPL strain on skin secreted chemical defences and life history traits during early ontogeny of agile frogs (Rana dalmatina) and common toads (Bufo bufo).ResultsExposure to Bd during the larval stage did not result in enhanced synthesis of the antimicrobial peptide Brevinin-1 Da in R. dalmatina tadpoles or in increased production of bufadienolides in B. bufo tadpoles. However, exposure to Bd during the larval stage had a carry-over effect reaching beyond metamorphosis: both R. dalmatina and B. bufo froglets contained smaller quantities of defensive chemicals than their Bd-naïve conspecifics in the control treatment. Prevalence of Bd and infection intensities were very low in both larvae and metamorphs of R. dalmatina, while in B. bufo we observed high Bd prevalence and infection intensities, especially in metamorphs. At the same time, we did not find a significant effect of Bd-exposure on body mass or development rate in larvae or metamorphs in either species.ConclusionsThe lack of detrimental effect of Bd-exposure on life history traits, even parallel with high infection intensities in the case of B. bufo individuals, is surprising and suggests high tolerance of local populations of these two species against Bd. However, the lowered quantity of defensive chemicals may compromise antimicrobial and antipredatory defences of froglets, which may ultimately contribute to population declines also in the absence of conspicuous mass-mortality events.

Morphological features and distribution of Trichinella sp. larvae in the muscles of the lynx

The purpose of the research is determination of optimal muscle tissue areas for confirmation of diagnosis in the lynx by trichinelloscopy.Materials and methods. The distribution of Trichinella sp. larvae were studied in spontaneously infected lynxes by the trichinelloscopy method when examining 72 sections in a compressorium. In addition to calculating the total number of isolated larvae and the percentage in muscles, we recalculated per 1 g of animal muscles and performed morphometry of the area and perimeter of Trichinella sp. capsules from various muscles, and calculated the ratio of the capsule length and width, and the M value (arithmetic mean): the area of the capsule and its perimeter. We determined the percentage ratio of the larva size to the capsule and the position in the myosymplast using the Vision Bio system (Epi 2014). The results were statistically processed using the Microsoft Excel software package. The larvae were photographed directly from the screen with digital signal processed by the Vision Bio system (Epi 2014).Results and discussion. It has been found that the capsules in the muscles are more often rounded (90% of all Trichinella sp. have a length-to-width ratio of 1.1 : 1). However, there are also oval capsules, the largest number of which was recorded in the masticatory muscles (33% of the total capsules in the masticatory muscles). When studying the selective expansion of larvae, it was found that the masticatory muscles, tongue, diaphragm and gastrocnemius muscles were the most populated. Conclusion. We identified high prevalence and intensity of infection in the lynx, which indicates not only the epizootic significance of the lynx in the spread of trichinellosis in the Kirov Region, but also its epidemiological significance as a source of infection. Due to the fact that the meat of this animal is eaten and there is a risk of human infection, it is necessary to examine the carcasses of these animals for trichinellosis by the compressor trichinelloscopy method or by the peptolysis method.

Status of Intestinal Helminth Infection in Schools Implementing the Home-Grown School Feeding Program and the Impact of the Program on Pupils in Anambra State, Nigeria.

Intestinal helminthiasis among pupils is a major impediment to their well-being and development. This 2-year study determined how home-grown school feeding programme (HGSFP) impacted on pupils' school attendance and created opportunity for more children to assess interventions geared towards the prevention and possible elimination of intestinal helminthiasis. Faecal samples were collected from 1677 consented pupils and examined for helminths using Kato-Katz technique. Pupils were treated with 40mg Levamisole (anti-helminthic) and re-examined. Structured questionnaires and focus group discussions were used to determine anthropometric indices and risk factors. A 6% prevalence rate which was not significant with respect to sex or age was observed. Helminth parasites observed were Ascaris lumbricoides (4.4%), Trichuris trichiura (0.8%), Hookworm spp. (0.2%), and Taenia spp. (0.5%). Two pupils (1.98%) recorded high intensity of infection (epg) while 98.02% had light infection. Ascaris lumbricoides voided following treatment were 290. The Body Mass Index (BMI) indicated that infected pupils had lower values (14.6317) compared to uninfected pupils (19.2003). The HGSFP significantly improved school attendance by 30%. Lack of knowledge about transmission (P = 0.0004), hand hygiene (P = 0.01) and usage of toilet (P = 0.01) were risk factors observed. Intestinal helminthiasis remains a public health problem among pupils because environmental and behavioural risk factors persist. HGSFP improved school attendance and created opportunity for more inclusive participation of school-aged children for deworming. This has great potential in fast-tracking the elimination of intestinal helminthiasis. The present study consequently advocates the need to sustain HGSFP in schools.

Morphomolecular and pathological study of Scaphanocephalus sp. in new host Siganus argenteus in the Arabian Gulf.

In this study, Scaphanocephalus parasite (Platyhelminthes: Heterophyidae) metacercariae were found in Siganus argenteus (forktail rabbitfish or streamlined spinefoot) in the Arabian Gulf of Jubail province, Saudi Arabia. The findings may constitute new host and locality records for this parasite. Based on the number of black spots containing parasite cysts per fish, our study indicated that Siganus argenteus had high infection intensities of encysted metacercariae belonging to the genus Scaphanocephalus. Of the 3500 S. argenteus specimens examined, 800 (22.9%) showed multiple black cysts over the entire body surface, including the membranous parts of fins, while none were seen on the internal organs. The prevalence of infection was highest in summer (June-August) (8.8%). The excysted metacercariae differed morphologically from previously identified Scaphanocephalus spp. Molecular analysis of rDNA showed 100% identity with an unnamed Scaphanocephalus sp. reported in Caribbean fish. Therefore, our findings may indicate a new species of this previously rarely recorded fish parasite. The histopathological examination revealed that the encysted parasites were restricted to the dermal layer of the skin and surrounded by melanophores and a fibrous connective tissue capsule, with focal myositis and Zenker's necrosis in the underlying muscle tissue. The characteristically 'winged' parasite was clearly observed within the cysts. The high prevalence of Scaphanocephalus infection in siganid fish we detected requires further epidemiological study.

Food chain, parasites and climate changes in the high Arctic: a case study on trophically transmitted parasites of common eider Somateria mollissima at Franz Josef Land

Assessment of the impact of climate change on the Arctic nearshore ecosystems requires knowledge of the “reference points”, that is, the state of things before the effects of the warming become pronounced. For parasites, which play an essential role in the nearshore ecosystems, this knowledge is scarce and fragmentary. This study, based on the materials collected at Franz Josef Land (FJL) in 1990–1993, partly fills this gap. We present the first data on the diet of the common eider Somateria mollissima at FJL, the transmission of helminths in its population and the infection of nearshore invertebrates with helminth larvae. We found that gastrointestinal helminth communities were impoverished (only ten species) and dominated by cestodes and acanthocephalans. This is associated with the prevalence of nearshore crustaceans, the intermediate hosts of these helminths, in the diet of the eiders. The absence of the vulnerable free-living larvae also facilitates transmission of helminths parasitizing eiders at FJL. Infection with helminths and the diet were different in ducklings and in adult birds as well as in eiders from different parts of the archipelago. The infection distribution of molluscs and crustaceans with helminth larvae was patchy and higher in the vicinity of the eider colonies. A high-infection intensity of FJL eiders with cestodes and acanthocephalans recorded in our study seems to have a certain negative effect on the bird population. Its significance is likely to grow considering that the transmission of helminths is promoted by the climate warming in the Arctic.

Ecological Scenarios and Parasite Diversity in Anurans of West Africa: A Review

This paper is a survey of the parasite diversity, prevalence and infection intensity in anurans in diverse ecological settings in West Africa. The settings included natural habitats (rainforests, freshwater creeks, Guinea and Sudan savannas), monoculture plantations (cocoa, cotton and oil palm), urbanized and urbanizing rainforest biotopes and polluted environments due to oil industry activities. The natural habitats had higher amphibian species diversity, moderate parasite prevalence and low infection intensity, showing a balance in the host/parasite relationship. These habitats yielded most of the monogeneans, among which were new species. The freshwater creek biotope had low amphibian diversity, but hosts from this environment harbored several parasite taxa, a situation attributed to a prolonged wet season, high environmental humidity and persistent breeding pools for insect vectors in this area. The monoculture plantations were characterized by high parasite prevalence but lower infection intensity. For example, in the Pendjari Biosphere Reserve in Bénin Republic, the Agricultural Zone (AZ) had higher parasite prevalence values, while the National Park (NP) and Buffer Zone (BZ) had higher infection intensities. Higher prevalence was attributed to the single or combined effects of vector population explosion, immune-suppression by agrochemicals, nutrient enrichment and eutrophication from fertilizer use. The lower infection intensity was attributed to the inhibitory effect of the pesticide-contaminated environment on the free-living larval stages of parasites. The adverse effect of pesticide contamination was also evident in the lower infection intensity recorded in the anurans from the cocoa plantations at Ugboke in comparison to those from the pesticide-free village settlement. Urbanization reduced host diversity and numbers and increased the vector population, resulting in unusually high parasite prevalence and infection intensities at Diobu and Port Harcourt and high prevalence recorded for Ophidascaris larvae in the anurans of Evbuabogun. Oil pollution in the mangrove community reduced both host and parasite diversity; infection intensity was also low due to the adverse conditions confronting free-living stages of parasites in their development milieu. The high prevalence values obtained for monogeneans (Polystoma spp.) in Ptychadena spp. from Ogoniland was presumed to have resulted from host tadpole sequestration and exposure to high oncomiracidia burden in the few hospitable ponds. Also reviewed is the phenomenon of amphibian paratenism, a strategy on which many helminth parasites rely on for their trophic transmission to their definitive hosts.

Prevalence and level of infection by endoparasites in different categories of sheep in the Western Amazon

This study aimed to understand the epidemiology of the main gastrointestinal endoparasites affecting sheep raised in the municipality of Sena Madureira, Acre, Brazil. A total of 178 fecal samples were collected from sheep raised in an extensive system of 10 farms. The samples were grouped into lambs, ewe lambs, lambing ewes, ewes, and rams for laboratory analysis by the flotation technique for counting eggs per gram of feces (EGF), oocysts of Eimeria sp., and presence of eggs of Moniezia sp. The analyzed variables consisted of the prevalence of nematodes, cestodes, and coccidia and intensity of strongylid and coccidium infection by quantification (mean ± SE) of eggs and oocysts. Prevalence data were compared by the chi-square test and intensity of infection (mean ± SE) by the Scott-Knott test (SAEG 9.1), both with P < 0.05. The overall prevalence was 77.6%, reaching 64.15% for strongylids, 36.2% for coccidia, and 8.81% for cestodes (Moniezia sp.). Ewes had the lowest prevalence (52.5%), while lambs had a prevalence of 95.5%, not differing from the others (P < 0.05). The intensity of infection by nematodes showed that lambs had the highest EGF compared to ewes, with values of 1297±270 and 232±79, respectively. The categories lambing ewes, ewes, and rams presented an average EGF below what is indicated for treatment with drugs. The highest intensity of infection was observed for ewe lambs (5859±3648), exceeding acceptable rates. Sheep raised in Sena Madureira has a high prevalence for verminosis by strongylids and a low prevalence for coccidiosis and cestodiasis. Young animal categories present a high health risk for endoparasitoses, and management measures that collaborate with the prophylaxis and control of these diseases should be adopted.

Prevalence and intensity of avian malaria in a quail hybrid zone.

Hybrid zones have been described as natural laboratories by researchers who study speciation and the various mechanisms that may affect gene flow. The evolutionary consequences of hybridization depend not only on reproductive compatibility between sympatric species, but also on factors like vulnerability to each other's predators and parasites. We examined infection patterns of the blood parasite Haemoproteus lophortyx, a causative agent of avian malaria, at a site in the contact zone between California quail (Callipepla californica) and Gambel's quail (C. gambelii). Controlling for the potential influence of sex and year, we tested whether species identity predicted infection status and intensity. We found that infection prevalence was lower in California and hybrid quail compared with Gambel's quail. However, infected California and hybrid quail had higher infection intensities than Gambel's quail. California and hybrid quail exhibited no significant differences in prevalence or intensity of infection. These findings suggest that infection by H. lophortyx has the potential to influence species barrier dynamics in this system; however, more work is necessary to determine the exact evolutionary consequences of this blood parasite on hybridization.

Deworming women of reproductive age during adolescence and pregnancy: what is the impact on morbidity from soil-transmitted helminths infection?

BackgroundSoil-transmitted helminths (STHs) are a major cause of poor health in low- and middle-income countries. In particular, hookworm is known to cause anaemia in children and women of reproductive age (WRA). One goal of the World Health Organization’s (WHO) 2030 roadmap for neglected tropical diseases is to reduce STH-related morbidity in WRA. As a minimal intervention, the WHO recommends deworming adolescent girls annually during human papilloma virus vaccination programmes and WRA during pregnancy and lactation. These routine interventions are low cost and can be implemented even by the most basic health services in endemic countries. In this study we use a cohort model to investigate the potential impact on STH-related morbidity in WRA.ResultsAnnual deworming treatment of adolescent girls reduces the prevalence of moderate- and heavy-intensity infections in this age group by up to 60% in moderate transmission settings and by 12–27% in high transmission settings. Treatment of WRA during pregnancy and lactation on its own has a small (< 20%) but significant effect on morbidity although it does not lead to the achievement of the morbidity target (< 2% moderate- to high-intensity infections) in this age group. However, depending on the age-intensity profile of infection, which may vary geographically, and assumptions on the density-dependence of egg production by fertilised female worms, continued school-based treatment may be able to reduce the force of infection acting on WRA, both through an indirect effect on the overall population-based force of infection and via reducing the burden of infection as children age and move into the WRA age classes. As a result, morbidity in WRA may be eliminated.ConclusionWhile deworming during pregnancy and lactation does not lead to the achievement of the morbidity target in WRA and its efficacy may vary by setting, it is still expected to be beneficial for maternity and child health. Monitoring of any WRA-based intervention is recommended to evaluate its effectiveness.Graphical

Clinical implications and treatment options of tungiasis in domestic animals.

Tunga penetrans, Tunga trimamillata and Tunga hexalobulata are the three species of sand fleas which cause tungiasis in domestic animals. Tunga penetrans and T. trimamillata are zoonotic in the tropical and sub-tropical endemic communities of Latin America and Africa. Tungiasis in animals frequently occurs alongside human tungiasis. Currently, most of the attention given to tungiasis is focusing on the human disease, and animal tungiasis is extremely neglected despite its public health and animal health significance. This review highlights recent findings concerning the clinical implications and treatment options but also summarises the occurrence, major features, public health and economic significance of tungiasis in domestic animals. Pigs, dogs, cats and domestic ruminants have been reported to harbour high intensities of sand fleas in endemic communities. High infection intensities cause significant animal morbidity which is often exacerbated by excoriations and secondary bacterial infections which are potentially fatal. In addition to the potential economic losses accruing from tungiasis-related morbidity, infected domestic animals contribute to transmission and persistence of sand fleas and eventually also to severe human disease. Although control of animal tungiasis is possible by adoption of proper husbandry practices, affected communities may not afford the resources required to implement them. Also, there are no widely acceptable and affordable insecticides for treatment of tungiasis in animals. Extension services aiming at increasing awareness on tungiasis and its control should be intensified. Also, available commercial insecticides should be evaluated for therapeutic and prophylactic properties against animal tungiasis.

Differentially Expressed Gene Patterns in Ascarid-Infected Chickens of Higher- or Lower-Performing Genotypes.

Simple SummaryNematode infections may increase mortality and welfare problems in laying hens. The two ascarid worms, Ascaridia galli and Heterakis gallinarum, are highly prevalent in laying hens kept in non-cage housing systems worldwide. The ability of a host to expel pathogens is a component of resistance to diseases. The molecular basis of differences between different host animals in their efficiency to expel worms is, however, not well understood. Therefore, we performed a detailed analysis of differentially expressed genes (DEGs) in two chicken genotypes (Lohmann Brown Plus (LB), Lohmann Dual (LD)), each with a lower or higher infection intensity level of A. galli and H. gallinarum. Our data showed significant upregulation of Guanylate Binding Protein 7 (GBP7) in LD hens. Gene ontology analysis revealed higher transcriptome activity related to “response to external stimulus” in LB hens, implying a higher stress response in this genotype. In contrast, LD hens showed higher transcriptomic expression of genes associated with a higher tolerance to infections.Here, we describe the first transcriptomic investigation of the peripheral blood of chickens exposed to Ascaridia galli and Heterakis gallinarum infections. We investigated differentially expressed gene (DEG) patterns in two chicken genotypes with either a higher (Lohmann Brown Plus, LB) or lower (Lohmann Dual, LD) laying performance level. The hens were experimentally coinfected with A. galli and H. gallinarum, and their worm burdens and infection parameters were determined six weeks post infection. Based on most representative infection parameters, the hens were clustered into lower- and higher-infection intensity classes. We identified a total of 78 DEGs contributing to infection-related phenotypic variation in the two genotypes. Our data showed significant upregulation of Guanylate Binding Protein 7 (GBP7) in LD hens, making it a promising candidate for tolerance to ascarid infections in chickens. Gene ontology analysis revealed higher transcriptome activity related to biological processes such as “response to external stimulus” in LB hens, implying a higher stress response in this genotype. In contrast, LD hens showed higher transcriptomic expression of genes related to ontology classes that are possibly associated with a higher tolerance to infections. These findings may help explain why lower-performing genotypes (i.e., LD) are less sensitive to infections in terms of maintaining their performance.

Influence of anthropogenic factors on the fauna of diplopods in the steppe zone of Ukraine

Various industries that constantly pollute the environment with their waste are quite well developed in the steppe zone of Ukraine. That in turn affects living organisms. The analysis of literature sources allowed to determine the factors influencing the diplopods fauna of the Steppe. Parasites, herbicides, fungicides, insecticides, heavy metals and other pollutants adversely affect invertebrates. Pesticides (glyphosate, imidacloprid, dimethoate, pirimiphos-methyl, propargite, cypermethrin, tebuconazole, chlorpyrifos, mefenoxam, mancozeb, sulfur, propiconazole, cyprodinil) are toxic to diplopods. They can affect lifetime, fertility, abundance, coordination of movements, feeding rates, change body weight and even in high concentrations cause the death of these animals. Sulfur, pirimiphos-methyl, propiconazole, imidacloprid, dimethoate and cypermethrin are the most toxic of all these pesticides. They cause the highest mortality. Heavy metals accumulate in the bodies of saprophages, reduce their abundance, affect body weight, cause a change in the intensity of eating food by diplopods. Nickel, lead, cadmium, zinc, cuprum and ferrum are toxic to millipedes. High concentrations of cadmium cause 100% mortality of Megaphyllum kievense (Lohmander, 1928). The development of urbanization causes a decrease in the abundance of saprophages. The species composition and number of individuals of some taxonomic groups of millipedes are reduced in reclamation areas. The nematodes Steinernema carpocapsae (Weiser, 1955) and Heterorhabditis heliothidis (Khan, Brooks &amp; Hirschmann, 1976) slow down the protective reactions of the body of Oxidus gracilis (C. L. Koch, 1847). The high intensity of diplopod infection with gregarines slows down the feeding process of Rossiulus kessleri (Lohmander, 1927). Lighting, soil humidity and the number of ants also affect the abundance of diplopods in natural forests and forest plantations of the steppe zone. Thus the diplopods are influenced by many environmental factors that can reduce their abundance in agrocenoses, forested and reclamation areas of the steppe zone of Ukraine.

ENDOPARASITES OF FORMOSAN BLACK BEARS (URSUS THIBETANUS FORMOSANUS) DURING ACORN SEASON IN YUSHAN NATIONAL PARK, TAIWAN.

Parasite infection is one of the most important factors in wildlife conservation. However, fecal parasite profiles of threatened Asiatic black bears (Ursus thibetanus) are only sporadically reported, and the effect of parasitic diseases on the survival of the locally endangered Formosan black bear (Ursus thibetanus formosanus) in Taiwan remains undetermined. The study objective was to investigate the gastrointestinal parasite profiles of Formosan black bears in Yushan National Park, the only known high-density habitat for the species in Taiwan. Bear fecal samples were collected in the acorn season (from October to February) from January 2008 to October 2012. To avoid bias created by repeat sampling, the parasite profiles of fecal samples collected in 2010 from 46 individually identified bears (which were identified by genetic analysis) were also examined. Parasites were isolated by various methods and identified by morphologic characteristics. A total of 220 samples were analyzed and the results were compared between seasons, sexes, and individuals. The overall frequency of parasite infection was 77.3%, and it varied by species, with Baylisascaris transfuga infection being the most frequent. We suggest that one factor underlying the high frequency and high intensity of infection that we observed is the fact that the bears seasonally congregated at high density in a small area. To our knowledge, this is the first thorough study of gastrointestinal parasites in Asiatic black bears. The long-term nature of the investigation and the relatively stable frequency and intensity of infection suggest that parasitic diseases could serve as bioindicators of ecosystem health.

Schistosomiasis Morbidity Hotspots: Roles of the Human Host, the Parasite and Their Interface in the Development of Severe Morbidity.

Schistosomiasis is the second most important human parasitic disease in terms of socioeconomic impact, causing great morbidity and mortality, predominantly across the African continent. For intestinal schistosomiasis, severe morbidity manifests as periportal fibrosis (PPF) in which large tracts of macro-fibrosis of the liver, visible by ultrasound, can occlude the main portal vein leading to portal hypertension (PHT), sequelae such as ascites and collateral vasculature, and ultimately fatalities. For urogenital schistosomiasis, severe morbidity manifests as pathology throughout the urinary system and genitals, and is a definitive cause of squamous cell bladder carcinoma. Preventative chemotherapy (PC) programmes, delivered through mass drug administration (MDA) of praziquantel (PZQ), have been at the forefront of schistosomiasis control programmes in sub-Saharan Africa since their commencement in Uganda in 2003. However, despite many successes, ‘biological hotspots’ (as distinct from ‘operational hotspots’) of both persistent high transmission and morbidity remain. In some areas, this failure to gain control of schistosomiasis has devastating consequences, with not only persistently high infection intensities, but both “subtle” and severe morbidity remaining prevalent. These hotspots highlight the requirement to revisit research into severe morbidity and its mechanisms, a topic that has been out of favor during times of PC implementation. Indeed, the focality and spatially-structured epidemiology of schistosomiasis, its transmission persistence and the morbidity induced, has long suggested that gene-environmental-interactions playing out at the host-parasite interface are crucial. Here we review evidence of potential unique parasite factors, host factors, and their gene-environmental interactions in terms of explaining differential morbidity profiles in the human host. We then take the situation of schistosomiasis mansoni within the Albertine region of Uganda as a case study in terms of elucidating the factors behind the severe morbidity observed and the avenues and directions for future research currently underway within a new research and clinical trial programme (FibroScHot).

Outbreak of gill henneguyosis in pond-cultured Oxyeleotris spp. (Eleotridae, Perciformes) caused by Henneguya shaharini Shariff, 1982 (Myxosporea: Bivalvulida) in south China

Henneguya shaharini Shariff is reported for the first time and found to be the possible cause of high rates of mortality in pond-reared marble goby, Oxyeleotris marmoratus Bleeker and Oxyeleotris lineolata Steindachner and the hybrid species of O. marmoratus (♀) ˟ O. lineolata (♂) in multiple major production areas of south China which expands the geographical distribution and host range of this parasite. This episode of epizootic gill henneguyosis had a distinct seasonal pattern which generally occurred from late December to middle May when water temperature ranged from 13 to 22 °C, but no significantly geographical bias was found. No remarkable clinical symptoms were found in affected fish with the early onset of disease. The severely infected fish, however, swam lonely and listlessly at the water surface and the gill filaments of moribund fish had much smudge attached. Upon necropsy, large amounts of myxosporean plasmodia of variable size could be found in the gill filaments. Histopathological investigations showed that the plasmodia were generally intralamellar, but rarely interlamellar and no distinct inflammatory responses surrounding the intact plasmodia were observed. The high infection intensity causing the displacement of gill filament by plasmodia and respiratory failure was possibly the main cause of fish mortality. Phylogenetic analysis indicated that H. shaharini clustered with two gill-infecting congeners to form an independent Gobioidei-infecting branch in a freshwater Henneguya cluster within a marine Henneguya-Myxobolus clade. The possible source of H. shaharini in China is discussed.

Effect of a trematode infection on growth, reproduction, and mortality of shorthead sculpin

Shorthead sculpin (Cottus confusus Bailey and Bond, 1963) in Birch Creek, Idaho, were infected with the trematode Euryhelmis cotti (Simon, 1972). Our objective was to determine if intensity of infection had an influence on growth, reproduction, and mortality of shorthead sculpin at two sites in Birch Creek. Prevalence of trematode infection was 100 % at the upstream site compared to 32 % prevalence at the downstream site; intensity of infection was at least 15 times greater in shorthead sculpin at the upstream site. von Bertalanffy growth models differed significantly between sites; the growth coefficient (K) was higher for sculpin at the upstream site. Gonadosomatic index for both males and females was significantly higher for sculpin found upstream. Females at the upstream site also had significantly more eggs per clutch compared to females at the downstream site. Annual mortality was significantly higher upstream (A = 57 %; 95 % CI = 52–62 %) compared to downstream (A = 42 %; 95 % CI = 38–46 %). Consequently, the density of sculpin was lower at the upstream site (13 fish/100 m2) compared to the downstream site (54 fish/100 m2). We did not find evidence to suggest that growth and reproduction of shorthead sculpin were influenced by infection of E. cotti, but rather were influenced primarily by density dependent factors. Mortality was higher for shorthead sculpin at the upstream site with high prevalence and intensity of infection. However, we do not know if higher mortality was a direct consequence of trematode infection or merely correlated with trematode infection.

Endemicity of Paragonimus and paragonimiasis in Sub-Saharan Africa: A systematic review and mapping reveals stability of transmission in endemic foci for a multi-host parasite system.

Paragonimiasis is caused by zoonotic trematodes of Paragonimus spp., found in Asia, the Americas and Africa, particularly in tropical regions. These parasites have a complex, multi-host life cycle, with mammalian definitive hosts and larval stages cycling through two intermediate hosts (snails and freshwater decapod crustaceans). In Africa, paragonimiasis is particularly neglected, and remains the only human parasitic disease without a fully characterised life cycle. However paragonimiasis has potentially significant impacts on public health in Africa, and prevalence has likely been underestimated through under-reporting and misdiagnosis as tuberculosis due to a similar clinical presentation. We identified the need to synthesise current knowledge and map endemic foci for African Paragonimus spp. together with Poikilorchis congolensis, a rare, taxonomically distant trematode with a similar distribution and morphology. We present the first systematic review of the literature relating to African paragonimiasis, combined with mapping of all reported occurrences of Paragonimus spp. throughout Africa, from the 1910s to the present. In human surveys, numerous reports of significant recent transmission in Southeast Nigeria were uncovered, with high prevalence and intensity of infection. Overall prevalence was significantly higher for P. uterobilateralis compared to P. africanus across studies. The potential endemicity of P. africanus in Côte d'Ivoire is also reported. In freshwater crab intermediate hosts, differences in prevalence and intensity of either P. uterobilateralis or P. africanus were evident across genera and species, suggesting differences in susceptibility. Mapping showed temporal stability of endemic foci, with the majority of known occurrences of Paragonimus found in the rainforest zone of West and Central Africa, but with several outliers elsewhere on the continent. This suggests substantial under sampling and localised infection where potential host distributions overlap. Our review highlights the urgent need for increased sampling in active disease foci in Africa, particularly using molecular analysis to fully characterise Paragonimus species and their hosts.