Cercarial Dermatitis in Schleswig-Holstein Distribution of Cercariae in Public Swimming Lakes

Cercarial dermatitis is a neglected zoonotic disease with distribution all over the world’s temperate zones. It is caused by cercariae, a larval stage of parasitic blood flukes of the genus Trichobilharzia that is a parasite of waterfowl. When cercariae burry into human skin, they trigger an allergic reaction that leads to severely itching papules. Goal of this research was to get an overview over the distribution of cercariae in the bathing places of Schleswig-Holstein, the most northern state of Germany. Therefore, all public bathing places were visited and searched for fresh water snails that are the potential intermediate hosts of cercariae. Water snails of different families and genera were collected and examined for the presence of cercariae. Water samples were taken and examined for cercariae via a microscope. Additionally slime samples of the water snails were taken to test a new, time saving method of detection. In total 8 different kinds of water snails were collected and examined, of which the families of Lymnaeidae and Planorbidae proved to be the most common hosts of cercariae. In total, the results indicate a spatial distribution of cercariae shedding snails all over Schleswig-Holstein.

Clinical Spectrum of Schistosomiasis: An Update

Schistosomiasis is a helminthic infection and one of the neglected tropical diseases (NTDs). It is caused by blood flukes of the genus Schistosoma. It is an important public health problem, particularly in poverty-stricken areas, especially those within the tropics and subtropics. It is estimated that at least 236 million people worldwide are infected, 90% of them in sub-Saharan Africa, and that this disease causes approximately 300,000 deaths annually. The clinical manifestations are varied and affect practically all organs. There are substantial differences in the clinical presentation, depending on the phase and clinical form of schistosomiasis in which it occurs. Schistosomiasis can remain undiagnosed for a long period of time, with secondary clinical lesion. Here, we review the clinical profile of schistosomiasis. This information may aid in the development of more efficacious treatments and improved disease prognosis.

An annotated checklist of Planorbinae (Heterobranchia, Hygrophila, Planorbidae) from northwestern Argentina

The family Planorbidae comprises freshwater gastropods with planispiral, spiral and limpet-shaped shells. Subfamily Planorbinae sensu stricto, has a richness of almost 300 species, with some of the main genera being Biomphalaria Preston, 1910 and Drepanotrema Fischer & Crosse, 1880. Some Biomphalaria species are of concern to human health as they are intermediate hosts of blood flukes in Latin America. In Argentina, the family Planorbidae is represented by 15 species in four genera. In Northern Argentina (NOA region), records of the family are scarce, and most of them are a result of occasional collecting. We provide an updated checklist of Planorbinae in NOA resulting from fieldwork, material in malacological collections, and data in the literature. Nine species occur in the area: four species of Biomphalaria and five of Drepanotrema. Among Biomphalaria species, we recorded Biomphalaria straminea (Dunker, 1848), which is considered a natural host of the blood fluke Schistostoma mansoni Sambon, 1907, for first time in Salta province; the known geographic distribution of B. straminea is extended in the country.

Development of a novel real-time polymerase chain reaction assay for the sensitive detection of Schistosoma japonicum in human stool

Background Elimination and control of Schistosoma japonicum, the most virulent of the schistosomiasis-causing blood flukes, requires the development of sensitive and specific diagnostic tools capable of providing an accurate measurement of the infection prevalence in endemic areas. Typically, detection of S. japonicum has occurred using the Kato-Katz technique, but this methodology, which requires skilled microscopists, has been shown to radically underestimate levels of infection. With the ever-improving capabilities of next-generation sequencing and bioinformatic analysis tools, identification of satellite sequences and other highly repetitive genomic elements for use as real-time PCR diagnostic targets is becoming increasingly common. Assays developed using these targets have the ability to improve the sensitivity and specificity of results for epidemiological studies that can in turn be used to inform mass drug administration and programmatic decision making. Methodology/Principal findings Utilizing Tandem Repeat Analyzer (TAREAN) and RepeatExplorer2, a cluster-based analysis of the S. japonicum genome was performed and a tandemly arranged genomic repeat, which we named SjTR1 (Schistosoma japonicum Tandem Repeat 1), was selected as the target for a real-time PCR diagnostic assay. Based on these analyses, a primer/probe set was designed and the assay was optimized. The resulting real-time PCR test was shown to reliably detect as little as 200 ag of S. japonicum genomic DNA and as little as 1 egg per gram of human stool. Based on these results, the index assay reported in this manuscript is more sensitive than previously published real-time PCR assays for the detection of S. japonicum. Conclusions/Significance The extremely sensitive and specific diagnostic assay described in this manuscript will facilitate the accurate detection of S. japonicum, particularly in regions with low levels of endemicity. This assay will be useful in providing data to inform programmatic decision makers, aiding disease control and elimination efforts.

Parasitological and molecular characterization of the avian schistosomatid cercariae infecting lymnaeidae snails in Phayao, Northern Thailand

Background and Aim: Cercarial dermatitis or swimmer's itch is an allergic skin reaction caused by penetrating cercaria of animal blood flukes. It is considered as a zoonotic water-borne skin condition that is found globally. Among the schistosomatid trematodes, avian schistosomes are the most responsible for cercarial dermatitis. Very little is known regarding the occurrence of dermatitis-causing cercariae in Thailand. Therefore, the objective of this study was to preliminarily investigate the presence of larval blood fluke infection among local lymnaeidae snails in Phayao by the incorporation of morphological and molecular methods. Materials and Methods: Overall 500 Radix (Lymnaea) rubiginosa (Michelin, 1831) were collected from freshwater reservoirs near Phayao Lake in San Kwan village in Phayao, Thailand, from October to December 2020. The snails were examined for avian blood fluke infection by the cercarial shedding technique followed by morphological and molecular characterization. Results: Only one type of furcocercous cercaria was observed to emerge from six infected snails (1.2%). Our molecular analyses demonstrated that the emerging cercariae showed most similarity to either the 28S ribosomal RNA gene (28S rDNA) or cytochrome oxidase C subunit 1 gene (cox1 or COI) sequences to those of Trichobilharzia species. In addition, phylogenetic tree analyses of both loci revealed similar results; the emerging cercariae were consistently clustered together with Trichobilharzia regenti. Conclusion: Our results clearly confirmed that the detected furcocercous cercariae belonged to the genus Trichobilharzia and displayed the highest homology to T. regenti. This study provides important data on the occurrence of dermatitis causing cercariae infection among local lymnaeidae snails, encouraging effective management, and control measures for this zoonotic infectious disease.

Prevalence and knowledge, attitude and practices related to schistosomiasis among primary school children in Chaani village, North “A” District, Zanzibar

Background: Schistosomiasis is a chronic, parasitic disease caused by blood flukes (Schistosoma species). It has been for along time a neglected tropical disease in most of the sub-Saharan countries.Methods: A cross sectional descriptive study was conducted between June 2015 to July 2015 at Chaani village in North “A” District. The school children were interviewed to identify activities which expose them frequently to water contact. Study subjects were selected by using stratified random sampling technique. The selected school children were asked to collect urine sample in well-labeled container. The samples were processed in the laboratory by using standard microbiological techniques (syringe filtration then examined by microscopy) and results were recorded, the data was analyzed.Results: Out of 170 School children 62 were infected with Schistosoma haematobium which is the predominant Schistosoma species found in that area. Among the 62, 45 (57.6%) were male and 17 (42.4%) were female. The level of knowledge of respondents on Schistosomiasis transmission is that 70% of school children have high knowledge, 18% have moderate knowledge and 12% have low knowledge. Other parameters were also assessed like bathing habits and knowledge and functions of Schistosomiasis control drug.Conclusions: Males were significantly more affected by the disease than females. Provision of safe water coupled with education of the communities regarding the modes of transmission of the disease and the way to prevent oneself, as well as provision of sanitary facilities, such as latrines may decrease the disease burden.

Bulinus senegalensis and Bulinus umbilicatus Snail Infestations by the Schistosoma haematobium Group in Niakhar, Senegal

Thorough knowledge of the dynamics of Bulinus spp. infestation could help to control the spread of schistosomiasis. This study describes the spatio-temporal dynamics of B. senegalensis and B. umbilicatus infestation by the Schistosoma haematobium group of blood flukes in Niakhar, Senegal. Molecular identification of the S. haematobium group was performed by real-time PCR, targeting the Dra 1 gene in 810 samples of Bulinus spp. collected during the schistosomiasis transmission season in 2013. In addition to Dra 1 PCR, a rapid diagnostic-PCR was performed on a sub-group of 43 snails to discriminate S. haematobium, S. bovis, and S. mattheei. Out of 810 snails, 236 (29.1%) were positive for Dra 1 based on the PCR, including 96.2% and 3.8% of B. senegalensis and B. umbilicatus, respectively. Among the sub-group, 16 samples were confirmed to be S. haematobium while one was identified as a mixture of S. haematobium and S. bovis. Snails infestations were detected in all villages sampled and infestation rates ranged from 15.38% to 42.11%. The prevalence of infestation was higher in the north (33.47%) compared to the south (25.74%). Snail populations infestations appear early in the rainy season, with a peak in the middle of the season, and then a decline towards the end of the rainy season. Molecular techniques showed, for the first time, the presence of S. bovis in the Bulinus spp. population of Niakhar. The heterogeneity of snail infestations at the village level must be taken into account in mass treatment strategies. Further studies should help to improve the characterizations of the schistosome population.