Bohumil Sak

Bohumil Sak
Czech Academy of Sciences, Biology Centre · Institute of Parasitology

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260
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Publications

Publications (260)
Article
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Background This study evaluated in vitro antigiardial activity in four Indonesian plants (Archidendron fagifolium, Diospyros sumatrana, Piper betle and Shorea sumatrana) extracted in methanol, methanol-tetrahydrofuran, and water. These plants exhibiting promising anti-parasitic activity were selected on the basis of collected behavioral data and th...
Article
We detected 24 Encephalitozoon cuniculi positive Ixodes ricinus ticks of 284 collected in the Czech Republic. Since the route of transmission of microsporidia is not fully understood, the presence of microsporidia in ticks raises the question of whether they may be involved in the transmission of these pathogens.
Article
We retrospectively analyzed of 211 frozen cerebrospinal fluid samples from immunocompetent persons in the Czech Republic and detected 6 Encephalitozoon cuniculi-positive samples. Microsporidiosis is generally underestimated and patients are not usually tested for microsporidia, but latent infection in immunodeficient and immunocompetent patients ca...
Article
Full-text available
Cryptosporidium spp., Enterocytozoon bieneusi and Encephalitozoon spp. are the most common protistan parasites of vertebrates. The results show that pigeon populations in Central Europe are parasitised by different species of Cryptosporidium and genotypes of microsporidia of the genera Enterocytozoon and Encephalitozoon. A total of 634 and 306 faec...
Article
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Cryptosporidium spp., Giardia intestinalis and microsporidia are unicellular opportunistic pathogens that can cause gastrointestinal infections in both animals and humans. Since companion animals may serve as a source of infection, the aim of the present screening study was to analyse the prevalence of these intestinal protists in fecal samples col...
Article
Total joint arthroplasty is a commonly used surgical procedure in orthopedics. Revision surgeries are required in >10% of patients mainly because of prosthetic joint infection caused by bacteria or aseptic implant loosening caused by chronic inflammation. Encephalitozoon cuniculi is a microsporidium, an obligate intracellular parasite, capable of e...
Article
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The question of how interactions between the gut microbiome and vertebrate hosts contribute to host adaptation and speciation is one of the major problems in current evolutionary research. Using bacteriome and mycobiome metabarcoding, we examined how these two components of the gut microbiota vary with the degree of host admixture in secondary cont...
Article
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Cryptosporidium Tyzzer, 1910 is one of the most common protistan parasites of vertebrates. The results of this study provide the first data on Cryptosporidium diversity in the European ground squirrel Spermophilus citellus (Linnaeus). A total of 128 faecal samples of European ground squirrels from 39 localities in the Czech Republic were analysed f...
Article
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Background Cryptosporidium spp. are globally distributed parasites that infect epithelial cells in the microvillus border of the gastrointestinal tract of all classes of vertebrates. Cryptosporidium chipmunk genotype I is a common parasite in North American tree squirrels. It was introduced into Europe with eastern gray squirrels and poses an infec...
Preprint
Full-text available
The question of how interactions between the gut microbiome and vertebrate hosts contribute to host adaptation and speciation is one of the major problems in current evolutionary research. Using bacteriome and mycobiome metabarcoding, we examined how these two components of the gut microbiota vary with the degree of host admixture in secondary cont...
Article
A total of 1,724 beef and 2,941 dairy cattle older than one year from 66 beef and 67 dairy farms in the Czech Republic were examined for the presence of rumen and liver fluke eggs in 2019-2022. Out of 227 positive animals, all were positive for paramphistome and five for fasciolid eggs. Molecular analysis of the ITS2 rDNA revealed the presence of C...
Chapter
Microsporidia are pathogenic organism related to fungi. They cause infections in a wide variety of mammals as well as in avian, amphibian, and reptilian hosts. Many microsporidia species play an important role in the development of serious diseases that have significant implications in human and veterinary medicine. While microsporidia were origina...
Article
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We identified Encephalitozoon cuniculi genotype II parasites as a cause of extraintestinal microsporidiosis in 2 owners of birds also infected with E. cuniculi. Patients experienced long-lasting nonspecific symptoms; the disease course was more progressive in a patient with diabetes. Our findings suggest direct bird-to-human transmission of this pa...
Article
Full-text available
Background Microsporidia of the genus Encephalitozoon are usually associated with severe infections in immunodeficient hosts while, in immunocompetent ones, microsporidiosis produces minimal clinically apparent disease. Despite their microscopic size, microsporidia are capable of causing systemic infection within a few days. However, the mechanisms...
Article
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Objectives: Patients with inflammatory bowel disease (IBD) are susceptible to intestinal opportunistic infections due to both defective mucosal immunity and altered immune response resulting from immunosuppressive treatment. Microsporidia infecting the gastrointestinal tract and causing diarrhoea can potentially affect the course of IBD. Methods: S...
Article
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Cryptosporidium spp. are common protozoan pathogens in mammals. The diversity and biology of Cryptosporidium in tree squirrels are not well studied. A total of 258 Eurasian red squirrels (Sciurus vulgaris) from 25 and 15 locations in the Czech Republic and Slovakia, respectively, were examined for Cryptosporidium spp. oocysts and specific DNA at th...
Article
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Zoonotic pathogen transmission is considered a leading threat to the survival of non-human primates and public health in shared landscapes. Giardia spp., Cryptosporidium spp. and Microsporidia are unicellular parasites spread by the fecal-oral route by environmentally resistant stages and can infect humans, livestock, and wildlife including non-hum...
Article
The aim of this work was to evaluate the effect of pasteurization and coagulation during goat cheese production on the infectivity of Encephalitozoon cuniculi spores for immunodeficient (SCID, CD4-/-, and CD8-/-) and immunocompetent (BALB/c and C57BL/6) mice. Goat milk and fecal samples were screened for the presence and quantity of microsporidial...
Article
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Cryptosporidium spp., common parasites of vertebrates, remain poorly studied in wildlife. This study describes the novel Cryptosporidium species adapted to nutrias (Myocastor coypus). A total of 150 faecal samples of feral nutria were collected from locations in the Czech Republic and Slovakia and examined for Cryptosporidium spp. oocysts and speci...
Article
Out of three genotypes of Encephalitozoon cuniculi (I–III) available for experimental studies, E. cuniculi genotype I remains the less characterized. This study describes for the first time individual phases of microsporidiosis caused by E. cuniculi genotype I and efficacy of albendazole treatment in immunocompetent BALB/c and C57Bl/6 mice and immu...
Article
Parasites of the genus Cryptosporidium Tyzzer, 1910 are one of the most common protistan parasites of vertebrates. Faecal samples from 179 red foxes (Vulpes vulpes [Linnaeus]), 100 grey wolves (Canis lupus Linnaeus), 11 golden jackals (Canis aureus Linnaeus), and 63 brown bears (Ursus arctos Linnaeus) were collected in the Czech Republic, Poland an...
Article
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Domesticated dogs (Canis lupus familiaris Linnaeus, 1758) are widely kept on all continents and could share parasites with free-living animals. To understand the transmission of intestinal parasites between dogs kept on the four dog stations and wildlife in Svalbard, 170 faecal samples from dogs and 203 faecal samples from wildlife, including Arcti...
Article
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The diversity and biology of Cryptosporidium that is specific for rats ( Rattus spp.) are not well studied. We examined the occurrence and genetic diversity of Cryptosporidium spp. in wild brown rats ( Rattus norvegicus ) by microscopy and polymerase chain reaction (PCR)/sequencing targeting the small subunit rDNA ( SSU ), actin and HSP 70 genes. O...
Article
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Background Microsporidia of the genus Encephalitozoon are generally connected with severe infections with lethal outcome in immunodeficient hosts. In immunocompetent hosts, microsporidiosis typically establishes a balanced host–parasite relationship that produces minimal clinically overt disease. Although the alimentary tract represents one of the...
Article
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Cryptosporidium baileyi, a bird-specific parasite, infects gastrointestinal, pulmonary, and urinary tracts of its host. We report on a C. baileyi infection associated with pulmonary hamartoma in an immunocompetent patient in Poland. Further work is needed to investigate the association between Cryptosporidium infections and tumors.
Article
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Background: Avian cryptosporidiosis is a common parasitic disease that is caused by five species, which are well characterised at the molecular and biological level, and more than 18 genotypes for which we have limited information. In this study, we determined the occurrence and molecular characteristics of Cryptosporidium spp. in farmed ostriches...
Article
Cryptosporidium is a genus of apicomplexan parasites that inhabit the respiratory and gastrointestinal tracts of vertebrates. Research of these parasites is limited by a lack of model hosts. This study aimed to determine the extent to which infection at the embryo stage can enhance the propagation of Cryptosporidium oocysts in chickens. Nine-day-ol...
Article
Encephalitozoon cuniculi genotype III disseminated intensively into most of the organs in all strains of mice, followed by a chronic infection with massive microsporidia persistence in immunodeficient mice and a partial decrease in C57Bl/6 mice. Treatment with 0.2 mg Albendazole/mouse/day temporarily reduces the number of affected organs in immunoc...
Article
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Out of four genotypes of Encephalitozoon cuniculi , E. cuniculi genotype II is considered to be a parasite that occurs in many host species in a latent asymptomatic form, whereas E. cuniculi genotype III seems to be more aggressive and infections caused by this strain can lead to the death of even immunocompetent hosts. Although Albendazole has bee...
Article
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The arctic fox (Vulpes lagopus), an apex predator with an omnipresent distribution in the Arctic, is a potential source of intestinal parasites that may endanger people and pet animals such as dogs, thus posing a health risk. Non-invasive methods, such as coprology, are often the only option when studying wildlife parasitic fauna. However, the dete...
Article
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Objectives: The potential linkage between Cryptosporidium spp. infection and colorectal human cancer was suggested by limited reports showing higher prevalence of C. parvum and C. hominis in patients with colon cancer. Here we conducted research concerning presence of Cryptosporidium spp. in malignant tissue collected from patients with colorectal...
Article
This study describes the prevalence and concentration of Encephalitozoon cuniculi spores in pork meat and evaluates the effect of sausage fermentation on E. cuniculi infectivity for immunodeficient (severe combined immunodeficient) and immunocompetent (BALB/c and C57BL/6) mice. Using a nested polymerase chain reaction (PCR) approach, E. cuniculi ge...
Article
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Microsporidia are emerging pathogens which cause an opportunistic infections in immunocompromised patients, especially those with AIDS. Intestinal microsporidiosis is the most recognized infection, whereas urinary tract infections caused by microsporidia are rarely paid attention to either due to their subclinical course or diagnostic difficulties....
Article
Objectives: Encephalitozoon spp. and Enterocytozoon bieneusi are intracellular parasitic fungi from the phylum Microsporidia, which initially localize to the intestine. As opportunistic pathogens, Encephalitozoon spp. in particular can disseminate to the respiratory tract, among other locations. Patients on life-long immunosuppression are at higher...
Article
Microsporidia are obligate intracellurar unicellular parasite of wide range of vertebrates. Although ingestion or inhalation of microsporidian spores is the main route of infection, assumed vertical transmission was described in some mammals. The present study was focused on proof of vertical transmission in mice under experimental conditions. Mice...
Article
Full-text available
The emergence of cryptosporidiosis, a zoonotic disease of the gastrointestinal and respiratory tract caused by Cryptosporidium Tyzzer, 1907, triggered numerous screening studies of various compounds for potential anti-cryptosporidial activity, the majority of which proved ineffective. Extracts of Indonesian plants, Piper betle and Diospyros sumatra...
Article
Full-text available
Fifteen Mongolian gerbils were inoculated with 10 × 10⁶ viable trophozoites of Giardia intestinalis. Their faeces were examined daily by flotation method and the number of shed cysts was counted. Two animals (male and female) were euthanised at 4- to 5-day intervals (9, 14, 18 days post-infection (DPI)). The remaining nine gerbils were sacrificed a...
Article
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Fecal samples from wild-caught common voles ( n = 328) from 16 locations in the Czech Republic were screened for Cryptosporidium by microscopy and PCR/sequencing at loci coding small-subunit rRNA, Cryptosporidium oocyst wall protein, actin and 70 kDa heat shock protein. Cryptosporidium infections were detected in 74 voles (22.6%). Rates of infectio...
Article
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A 23 year-old, HIV-negative women who underwent hematopoietic stem cell transplantation was admitted to the hospital with respiratory failure and symptoms of bronchiolitis obliterans. The chest CT scan revealed diffuse ground glass opacification and fibrous plugs. Due to worsening respiratory failure despite treatment, ventilation through tracheost...
Article
Microsporidia are a group of obligate intracellular eukaryotic parasites, which are able to infect a wide range of animals, including humans. Four genotypes of Encephalitozoon cuniculi have been found to date. The different courses of microsporidiosis described in humans, which are dependent on immunological status of the host and genotype of E. cu...
Article
Full-text available
Background: Among patients with hip joint endoprosthesis, periprosthetic osteolysis is the most common complication following primary arthroplasty, and subsequent implant loosening is the leading cause of arthroplasty revision. Causes of stability loss, though not always evident, can be mechanical, allergic, or infectious (bacterial and fungal age...
Article
Faecal samples from striped field mice (n = 72) and yellow-necked mice (n = 246) were screened for Cryptosporidium by microscopy and PCR/sequencing. Phylogenetic analysis of small-subunit rRNA, Cryptosporidium oocyst wall protein and actin gene sequences revealed the presence of C. parvum, C. hominis, C. muris and two new species, C. apodemi and C....
Article
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Faecal samples were collected from cats kept as pets (n = 120) and stray cats (n = 135) in Central Europe (Czech Republic, Poland and Slovakia) and screened for the presence of Cryptosporidium spp., Giardia intestinalis (Kunstler, 1882), Encephalitozoon spp. and Enterocytozoon bieneusi Desportes, Le Charpentier, Galian, Bernard, Cochand-Priollet, L...
Article
Full-text available
Piper betle has been used as a medicinal plant in traditional medical systems throughout South and South East Asia. Experimental studies have revealed its wide and diverse biological and pharmacological effects. In this study, antigiardial activity of Piper betle was tested using experimental infections of Giardia intestinalis, the most common caus...
Article
This study revises our understanding of the effectiveness of cell-mediated adaptive immunity and treatment against microsporidia using molecular detection and quantification of microsporidia in immunocompetent C57Bl/6 and immunodeficient CD4-/- and CD8-/- mice for the first time. We demonstrate an intense dissemination of microsporidia into most or...
Article
Full-text available
We undertook a study on Cryptosporidium spp. in wild cricetid rodents. Fecal samples were collected from meadow voles ( Microtus pennsylvanicus ), southern red-backed voles ( Myodes gapperi ), woodland voles ( Microtus pinetorum ), muskrats ( Ondatra zibethicus ) and Peromyscus spp. mice in North America, and from bank voles ( Myodes glareolus ) an...
Article
This study investigated the prevalence, genetic diversity, and zoonotic concerns of microsporidia in household dogs and cats in Poland. A total of 126 (82 dogs and 44 cats) fecal specimens were analyzed for the presence of specific DNA of Enterocytozoon bieneusi and Encephalitozoon spp. using a nested PCR protocol amplifying the internal transcribe...
Article
Encephalitozoon cuniculi is probably the most common microsporidia which infects a wide range of vertebrates, including human. So far, four genotypes of this parasite have been identified based on the rRNA internal transcribed spacer variations. The course of infection caused by E. cuniculi III had very massive onset in immunocompetent host charact...
Article
The present study was undertaken to describe Cryptosporidium spp. infection in tree squirrels from 17 locations in Northern Italy. A total of 357 squirrels were examined, including species native to Europe (Sciurus vulgaris; n=123), and species introduced from North America (Sciurus carolinensis; n=162) and Southeast Asia (Callosciurus erythraeus;...
Article
Full-text available
Helminths and bacteria are major players in the mammalian gut ecosystem and each influences the host immune system and health. Declines in helminth prevalence and bacterial diversity appear to play a role in the dramatic rise of immune mediated inflammatory diseases (IMIDs) in western populations. Helminths are potent modulators of immune system an...
Data
Hematology line graph panel–red blood cells indices. Abundance of red blood cells indices–MCH, MCHC and MCV in blood samples of rats infected with Hymenolepis diminuta (dark grey, n = 4) and healthy, uninfected rats (light grey, n = 4). The samples were taken before infection, during the pre-patent period (after infection before establishment), and...
Data
OTU table highlighting changes in response to helminth infection. OTUs are identical sequences (100% similarity). Bonferroni corrected Kruskal Wallis test results are shown comparing 1) samples from the time period before infection to the patent period and 2) comparing samples from the infected versus control group all within the patent period. Rel...
Data
Statistical similarity in community composition (beta diversity). Three-factor PERMANOVA with time period, treatment group, and rat nested within treatment group. Model includes interaction between treatment group and time period. Test used unrestricted permutation of raw data and Type III sum of squares. Bray-Curtis dissimilarity metric. (DOCX)
Data
Flow cytometry boxplot panel figure—double positive T-cell populations. Abundance of double-positive T-cell populations in flow cytometric samples from rats infected with Hymenolepis diminuta (dark grey, n = 4) and uninfected rats (light grey, n = 4). The error bars represent the 95% confidence intervals for the mean leukocyte cell counts at each s...
Data
Hematology line graph panel–red blood cells. Abundance of red blood cells, hemoglobin and hematocrit in blood samples of rats infected with Hymenolepis diminuta (dark grey, n = 4) and healthy, uninfected rats (light grey, n = 4). The samples were taken before infection, during the pre-patent period (after infection before establishment), and at two...
Data
Hematology line graph panel–specific leukocyte populations. Abundance of specific leukocyte populations (basophils, eosinophils, lymphocytes, monocytes and neutrophils) in blood samples of rats infected with Hymenolepis diminuta (dark grey, n = 4) and healthy, uninfected rats (light grey, n = 4). The samples were taken before infection, during the...
Data
Phylum specific analyses. Before infection includes 12 time points, prepatent period includes 4 time points, and patent period includes 11 time points. A and B) Alpha diversity, as measured by the Shannon diversity index, of Bacteroidetes and Firmicutes phyla. A) Shannon diversity within the Bacteroidetes phylum increases in response to helminth in...
Data
Comparison of community composition within time periods. Nested PERMANOVA analyses (rat nested within treatment group) were run to differences in community composition similarity before infection (12 time points), in the prepatent period (4 time points), and in the patent period (11 time points). Beta diversity metrics: UW–unweighted UniFrac, W–wei...
Data
Flow cytometry boxplot panel figure—T-cell populations. Abundance of T-cell populations in flow cytometric samples from rats infected with Hymenolepis diminuta (dark grey, n = 4) and uninfected rats (light grey, n = 4). The error bars represent the 95% confidence intervals for the mean cell counts at each sample location for each group. The asteris...
Data
Flow cytometry boxplot panel figure—double negative T-cell populations. Abundance of double-negative T-cell populations in flow cytometric samples from rats infected with Hymenolepis diminuta (dark grey, n = 4) and uninfected rats (light grey, n = 4). The error bars represent the 95% confidence intervals for the mean leukocyte cell counts at each s...
Article
Full-text available
The present study was conducted to evaluate the methanolic extracts from several plant leaves widely used in traditional medicine to cure digestive tract disorders and in the self-medication of wild animals such as non-human primates, namely Archidendron fagifolium, Diospyros sumatrana, Shorea sumatrana, and Piper betle leaves, with regard to their...
Article
Full-text available
A total of 345 faecal samples were collected from domestic, captive and wild birds in rural areas, urban areas and a Zoo in Algeria. Samples were screened for the presence of parasites belonging to the genus Cryptosporidium Tyzzer, 1910 by microscopy and PCR analysis of the small-subunit rRNA (SSU), actin and 60-kDa glycoprotein (gp60) genes. Crypt...
Article
This study investigated the prevalence of Cryptosporidium in farmed fur animals in the Czech Republic and Poland. A total of 480 faecal samples were collected from fur animals, including 300 American mink (Mustela vison), 60 silver foxes (Vulpes vulpes), 50 long-tailed chinchillas (Chinchilla lanigera), and 70 nutrias (Myocastor coypus), at 14 farm...
Article
Full-text available
Understanding of the diversity of species of Cryptosporidium Tyzzer, 1910 in tortoises remains incomplete due to the limited number of studies on these hosts. The aim of the present study was to characterise the genetic diversity and biology of cryptosporidia in tortoises of the family Testudinidae Batsch. Faecal samples were individually collected...
Article
Excystation of sporozoites of Cryptosporidium parvum from oocysts is essential for successful in vitro assays. It has also been traditionally used as a measure for oocyst viability and infectivity. Laboratories use various excystation protocols so there is a need to clarify which method is the best. In this study, six different protocols for in vit...
Article
Full-text available
Cryptosporidium is an opportunistic protozoan parasite that can cause severe diarrhoea in immunocompromised patients. The transmission of this pathogen in humans and animals is not fully understood. C. meleagridis, originally described in birds, is the only Cryptosporidium species known to naturally infect mammalian and avian species. This study do...