Morphologic study of the effect of iron on pseudocyst formation in Trichomonas vaginalis and its interaction with human epithelial cells.

BACKGROUND: Trichomonas vaginalis is the aetiological agent of human trichomoniasis, which is one of the most prevalent sexually transmitted diseases in humans. Iron is an important element for the survival of this parasite and the colonisation of the host urogenital tract. OBJECTIVES: In this study, we investigated the effects of iron on parasite proliferation in the dynamics of pseudocyst formation and morphologically characterised iron depletion-induced pseudocysts. METHODS: We performed structural and ultrastructural analyses using light microscopy, scanning electron microscopy and transmission electron microscopy. FINDINGS: It was observed that iron depletion (i) interrupts the proliferation of T. vaginalis, (ii) induces morphological changes in typical multiplicative trophozoites to spherical non-proliferative, non-motile pseudocysts, and (iii) induces the arrest of cell division at different stages of the cell cycle; (iv) iron is the fundamental element for the maintenance of typical trophozoite morphology; (v) pseudocysts induced by iron depletion are viable and reversible forms; and, finally, (vi) we demonstrated that pseudocysts induced by iron depletion are able to interact with human epithelial cells maintaining their spherical forms. MAIN CONCLUSIONS: Together, these data suggest that pseudocysts could be induced as a response to iron nutritional stress and could have a potential role in the transmission and infection of T. vaginalis.

Morphologic study of the effect of iron on pseudocyst formation in Trichomonas vaginalis and its interaction with human epithelial cells

BACKGROUND Trichomonas vaginalis is the aetiological agent of human trichomoniasis, which is one of the most prevalent sexually transmitted diseases in humans. Iron is an important element for the survival of this parasite and the colonisation of the host urogenital tract. OBJECTIVES In this study, we investigated the effects of iron on parasite proliferation in the dynamics of pseudocyst formation and morphologically characterised iron depletion-induced pseudocysts. METHODS We performed structural and ultrastructural analyses using light microscopy, scanning electron microscopy and transmission electron microscopy. FINDINGS It was observed that iron depletion (i) interrupts the proliferation of T. vaginalis, (ii) induces morphological changes in typical multiplicative trophozoites to spherical non-proliferative, non-motile pseudocysts, and (iii) induces the arrest of cell division at different stages of the cell cycle; (iv) iron is the fundamental element for the maintenance of typical trophozoite morphology; (v) pseudocysts induced by iron depletion are viable and reversible forms; and, finally, (vi) we demonstrated that pseudocysts induced by iron depletion are able to interact with human epithelial cells maintaining their spherical forms. MAIN CONCLUSIONS Together, these data suggest that pseudocysts could be induced as a response to iron nutritional stress and could have a potential role in the transmission and infection of T. vaginalis.

Fatores associados à ocorrência de parasitoses intestinais em uma população de crianças e adolescentes / Factors associated with intestinal parasitosis in a population of children and adolescents

OBJETIVOS: Analisar a prevalência de infecções por parasitos intestinais em crianças e adolescentes matriculados em escolas de ensino fundamental no município de SÃO João del-Rei, Minas Gerais, e os fatores associados à infecção. MÉTODOS: Estudo epidemiológico seccional, realizado entre março/2008 e julho/2009. Foram realizados exames coproscópicos por sedimentação espontânea e Kato-Katz em 1.172 escolares. Foram ajustados modelos de regresSÃO logística múltipla para o estudo dos fatores associados às infecções em geral e, separadamente, por helmintos e por protozoários. RESULTADOS: A prevalência de infecções foi de 29%, havendo uma variação de 7 a 83%, respectivamente, entre as escolas de menor e maior ocorrência. A presença de instalação sanitária no domicílio foi associada a uma ocorrência menor de helmintos; o aumento na idade dos escolares associou-se a uma maior ocorrência de protozoários e de parasitos em geral; enquanto a presença de filtro de água e a localização do domicílio em área urbana mostraram-se associadas a uma ocorrência menor dos três desfechos analisados. Em todas as regiões, foi registrado o consumo de medicação preventiva contra helmintos. CONCLUSÕES: Desigualdades nas condições de vida tornaram as prevalências diferenciadas entre as regiões do estudo. O estudo ressalta a necessidade de promover o uso de filtros de água nas residências de áreas endêmicas e de avaliar o consumo preventivo de medicamentos anti-helmínticos na dinâmica e na SAÚDE dos indivíduos. Medidas de controle que levem em conta os fatores descritos devem ser prioritárias em nível de SAÚDE PÚBLICA.