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Rodent trypanosomes: occurrence, development and transmission
Valsová, Iveta ; Votýpka, Jan (advisor) ; Kodym, Petr (referee)
Trypanosomes of the subgenus Herpetosoma are considered highly host-specific and nonpathogenic to their hosts. They are commonly found in rodents (and some insectivores), and fleas are believed to be their vectors. Around 50 trypanosome species have gradually been assigned to this subgenus, mainly based on the morphology of blood forms and their host specificity. However, due to the application of molecular methods, this number is beginning to increase. This thesis aims to investigate the prevalence and evolution of trypanosomes of the subgenus Herpetosoma in different mammalian hosts and their fleas in the Czech Republic. In total, samples from 17 mammalian species (mainly rodents) were tested for the presence of trypanosomes; only three species were found: with 1% prevalence Trypanosoma in the bank vole (Clethrionomys glareolus) similar to T. microti (typical for the field vole, Microtus agrestis), with 4% prevalence T. grosi in field mice (Apodemus spp.), and with 40% prevalence Trypanosoma sp. B08-471 in the European edible dormice (Glis glis). This trypanosome species was also detected in the flea Ceratophyllus (Monopsyllus) sciurorum, which is a typical ectoparasite of edible dormice. In fleas, the development of trypanosomes and also commonly occurring monoxenous trypanosomatids of the genus...
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The role of Toxoplasma gondii in human infertility - host manipulation or a side effect of the disease
Hlaváčová, Jana ; Kaňková, Šárka (advisor) ; Kodym, Petr (referee) ; Fajfrlík, Karel (referee)
Approximately one-third of the world's population is infected with the parasitic protozoan Toxoplasma gondii (T. gondii). Besides the classical sources of infection, sexual transmission of the parasite has recently been discussed and confirmed in many animal species. However, only indirect evidence supports this mode of transmission in humans. Our study found that Toxoplasma-seropositivity of sexual partner was a risk factor for T. gondii infection in women. These results supported the hypothesis of unidirectional male-to-female sexual transmission. We further proposed the hypothesis of T. gondii transmission during oral sex when an uninfected individual ingests the ejaculate of an infected man. If the ejaculate contained tissue cysts of the parasite, a mode of infection similar to ingesting the parasite in raw meat would be expected. To determine whether T. gondii is indeed present in the semen of men, we subsequently conducted a study in which we were the first to demonstrate the presence of tissue cysts of the parasite in the semen of men with latent toxoplasmosis. The impact of toxoplasmosis was also investigated in relation to reproductive functions. A higher prevalence of toxoplasmosis was found in infertile men compared to controls. In our study, we found that latent toxoplasmosis negatively...
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Comparison of different rodent species as hosts of human pathogenic leishmania.
Vojtková, Barbora ; Sádlová, Jovana (advisor) ; Kodym, Petr (referee) ; Shaw, Jeffrey Jon (referee)
6 ABSTRACT Leishmania parasites (Kinetoplastida: Trypanosomatidae) are causative agents of leishmaniases, a group of vector-borne diseases with various manifestations and complex epidemiology. Principal vectors are sand flies (Diptera: Psychodidae) and among mammalian hosts, rodents are predominantly represented. Rodents are also the most common laboratory models for the research of leishmaniases. However, reservoirs of most Leishmania species are still poorly recognized and the scope of standard model hosts is still insufficient to mimic well the wide spectrum of leishmaniases. This PhD thesis summarizes three different topics, all dealing with experimental infections of rodents with important human parasites - Leishmania major and L. donovani. The first topic was focused on the effect of sand fly saliva on the development of cutaneous leishmaniasis. BALB/c mice infected intradermally with L. major were repeatedly bitten by P. duboscqi females every two weeks. The multiple and repeated sand fly bites significantly enhanced the development of cutaneous lesions and increased parasite load. The second topic was aimed at enrichment of the spectrum of laboratory model animals for Leishmania research. Three Asian rodent species (Cricetulus griseus, Lagurus lagurus and Phodopus sungorus) were infected with L....
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Sexual transmission of Toxoplasma gondii from males to females: experimental verification using laboratory animal model
Navrátil, Jiří ; Kodym, Petr (advisor) ; Votýpka, Jan (referee)
Toxoplasma gondii is cosmopolitly living parasite which prevalence in human extends to tens of percent. In its life cycle it uses any homoiothermic vertebrate as an intermediate host. The definitive host are felines from Felidae family. The acute phase of infection is medically important in immunocompromised pacients and by its risk of congenital toxoplasmosis in pregnant women who never suffered from this illness before. Infection could have serious and rarely even lethal consequences in both cases. This thesis focuses on experimental verification of theory of sexual transmission of toxoplasmosis from male to female on laboratory mice. Possible transmission was tested in acute phase and latent phase of infection. The result was negative in both cases. Moreover, we observed the parasite's affinity to tissue of organs in male mice by PCR technique. Particularly, our interest was in comparing genital organs with others. It was discovered that lungs and spleen are the most infected organs in acute phase of infection. Toxoplasma was also present in genital organs (especially in epididymis) but not more frequently than in others. We observed statistically significant difference between sexual and non-sexual organs in acute and latent toxoplasmosis - non-sexual organs were more infected in both phases....
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Role of asymptomatic hosts in leishmaniasis transmission.
Sandner, Bruno ; Sádlová, Jovana (advisor) ; Kodym, Petr (referee)
Leishmania parasites have a digenetic-life cycle, circulating between vertebrate hosts and insect vectors, mainly phlebotomine sand flies (Diptera: Phlebotominae). Mammals serve as principal reservoirs of the disease and maintain the leishmania population even in the absence of the vector. Knowledge of the role of asymptomatic hosts in parasite transmission is one of the key prerequisites to understand epidemiology of leishmaniases. The aim of this work is to summarize the studies on asymptomatic hosts of visceral leishmaniasis caused by L. infantum and L. donovani. In L. infantum, asymptomatic hosts have been shown to be involved in transmission, namely dogs, humans, and other putative reservoir hosts. Asymptomatic dogs infect the same proportion of vectors as symptomatic dogs, and in humans, HIV coinfection significantly increased the infectiousness. VL caused by L. donovani is regarded as mostly anthroponotic, but the parasite has been often detected in animal hosts and zoonotic transmission has been suggested in East Africa. Transmission from asymptomatic individuals has not been established, but the studies on this topic are very scarce. Further intensive research is needed to confirm the role of potential reservoir hosts and asymptomatic individuals in the transmission of leishmaniases....
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Role of catalase and chitinase in the life cycle of Leishmania parasites
Glanzová, Kristýna ; Sádlová, Jovana (advisor) ; Kodym, Petr (referee)
Leishmaniasis is an infectious disease caused by protozoa of the genus Leishmania (Kinetoplastida: Trypanosomatidae) which are transmitted by phlebotomine sand flies (Diptera: Phlebotominae). For the dixenous life cycle, leishmania parasites are equipped with enzymes that facilitate survival in both insect vectors and mammalian hosts. Gene for the enzyme catalase which protects cells from reactive oxygen species by the elimination of H2O2 and is present in related monoxenous trypanosomatids is, however, missing in Leishmania genome. Chitinase can be involved in the interaction of leishmania parasites with chitin-containing structures in sand flies (peritrophic matrix, stomodeal valve). The expression of the enzyme in amastigotes suggests its significant function also in the mammalian host. I tested the role of these enzymes in the life cycle of leishmania by direct comparison of L. mexicana mutants (i) with inserted catalase gene and (ii) with deleted chitinase gene with control groups. I conducted experimental infections of Lu. longipalpis including transmission of leishmania to the hosts by bite, tested the survival of leishmania in macrophages and performed experimental infections of BALB/c mice followed by xenodiagnoses. The experiments confirmed that the presence of catalase in leishmania does...
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Effects of Toxoplasmosis on Reaction Times and Prepulse Inhibition of Startle Reaction in Humans
Příplatová, Lenka ; Flegr, Jaroslav (advisor) ; Kodym, Petr (referee) ; Vyas, Ajay (referee)
Effects of Toxoplasmosis on Reaction Times and Prepulse Inhibition of Startle Reaction in Humans vi Abstract Toxoplasma gondii, a single-cell coccidia from almost exclusively parasitic phylum Apicomplexa, does not typically cause acute health issues in humans with most exceptions among immunodeficient individuals and pregnant mothers or, more precisely, their offspring. In the latent phase, the bradyzoites in tissue cysts placed most often in neural and muscle tissues can evolve pressure on the host's body both as a collateral effect of the presence of the parasitic organism in host's tissues and as a consequence of adaptive evolution leading to increase in probability of trophic transmission to the final host, a felid. In humans, this can result in slight changes in personality profiles, deterioration of psychomotor and cognitive functions, and development of serious mental disorders. The thesis focuses predominantly on one of the aspects of the changes, namely the effect of latent toxoplasmosis on the processing of startle signals themselves and when modified by a preceding low-intensity signal; this processing may be connected with the development of schizophrenia in predisposed individuals. Studies conducted within the project framework found changes int the speed of signal processing in...
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Sauroleishmania: development in the vectors and hosts
Tichá, Lucie ; Volf, Petr (advisor) ; Kodym, Petr (referee)
Leishmania of subgenus Sauroleishmania are parasites of reptiles, most often lizards, and are not pathogenic for humans. Therefore, they are neglected group of pathogens and their life cycle is not well-known. They are transmitted probably by ingestion of infected vector which is usually considered as sand flies of genus Sergentomyia (Diptera: Psychodidae). Sauroleishmania are traditionally denominated in Hypopylaria and it is expected that their development is limited to sand fly hindgut. The main aim of this work is to summarize the present knowledge about Sauroleishmania life cycle and to elucidate some aspects of their development in the vector and host. In the first part of thesis we studied development of four Sauroleishmania species in various sand flies of genera Sergentomyia and Phlebotomus. Late-stage infections of Leishmania (S.) adleri and L. (S.) hoogstraali were found in six and two sand fly species, respectively. Hypopylarian infections of Leishmania (S.) adleri were found in Se. schwetzi, P. papatasi and P. sergenti, while in P. argentipes, P. orientalis and P. duboscqi this Sauroleishmania migrated anteriorly in the midgut (peripylarian development). Similar type of development was observed also in P. argentipes and P. orientalis infected by Leishmania (S.) hoogstraali. Both L....
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