Egress, which describes the mechanism that some intracellular parasites use to exit from parasitophorous vacuoles and host cells, plays a very important role in the parasite life cycle and is central to Eimeria propagation and pathogenesis. Despite the importance of egress in the intracellular parasite's life cycle, very little information is known on this process compared to other steps, e.g., invasion. The present study was conducted to investigate the interplay between the host adaptive immune system and Eimeria egression. Splenic lymphocytes or soluble immune factors were incubated with parasite-infected host cells for 3 or 5 h, and the percentage of egress was calculated according to an established formula. Viability of egressed parasites and host cells was tested using trypan blue exclusion and annexin V and propidium iodide staining, respectively. We found that premature egression of sporozoites from Eimeria tenella-infected primary chicken kidney cells or from chicken peripheral blood mononuclear cells occurred when the cells were cocultured in vitro with spleen lymphocytes from E. tenella-infected chickens but not when they were cocultured with splenocytes from uninfected chickens. Eimeria-specific antibodies and cytokines (gamma interferon [IFN-␥], interleukin-2 [IL-2], and IL-15), derived from E. tenella-primed B and T lymphocytes, respectively, were capable of promoting premature egress of sporozoites from infected host cells. Both egressed parasites and host cells were viable, although the latter showed reduced reinvasion ability. These results suggest a novel, immune-mediated mechanism that the host exploits to interrupt the normal Eimeria life cycle in vivo and thereby block the release of mature parasites into the environment.
Background: Methylene blue was used as a vital stain for the assessment of viability of protoscolices from hydatid cysts taking advantage of the chemical nature of the dye as a redox indicator and the kinetically distinct molecular transfer systems of Echinococcus protoscolex for uptake of materials across the tegument. Aim: The present study attempts to validate the application of methylene blue staining for assessment of viability of protoscolices. Methods: To validate the criteria by which viability is assessed, control tests were performed using normal protoscolices and protoscolices previously treated with distilled water at 60°C for 5 minutes. Performance of methylene blue was further studied at intervals over a period of 50 minutes after protoscolex exposure using 1% dye concentration. Results: Normal protoscolices were able to adsorb and reduce the dye and have, therefore, lost the blue color. Protoscolices previously treated with warm water on the other hand, being functionally dead, failed to reduce the adsorbed dye and permanently retained the blue color. Results also indicated that a clear distinction between dead and alive protoscolices can be made within 1 minute. Reading of the test after 10 minutes would be misleading giving a false result. Conclusion: These findings suggest that viability of protoscolices can be assessed on the basis of acquisition and loss/retaining of the dye blue color. Increasing the concentration of methylene blue to 1% was noticed to be associated with remarkable enhancement of contractility, sucker movement, and evagination. Such an excitatory action of the dye may be exploited in viability tests which adopt these criteria.
Aim of the Study: To assess the bacterial contamination in drinking water sources in Khartoum/ Sudan. Place of Study: Central Veterinary Research Laboratory/ Bacteriology Department. Study Design: One hundred water samples were collected from the three localities of Khartoum state (Khartoum= 33, Omdurman= 34, Khartoum north [Bahri] =25) and 8 from different companies of water supply. Methodology: Fifty four Samples were collected from surface water and (38) from ground water [well]. These samples transported to bacteriology lab for microbiological analyses using filtration method and new technique Colilert and Pseudalert kits which used for the first time in Sudan. Results: Filtration method revealed different bacterial species, they were: Escherichia coli, Klebsiella pneumoniae, Enterobacter aerogene Enterobacter sakazaki, Enterobacter cloacae, Serratia marinoruba, Proteus mirabilis, Salmonella spp. Raoultella terrigena\planticola, Orchobacter anthrobi, Cronobater spp., Aeromonas salmonicida, Aeromonas hydrophilia, Pantoea agglomerans, Vibrio parahaemolyticus. Coliform bacteria, Escherichia coli and Pseudomonas app were detected and most probable numbers (MPN) were counted using the previous kits according to manufacture instructions. Conclusion: The water must be tested before using and quality control technique must be achievable to ensure continuously supply of pure drinking water.
Food-borne diseases in general have received more attention in the last decade, but little attention has been paid to parasitic food-borne infections. This is probably due to the fact that they are not associated with acute illness as bacterial and viral infections do. In the Sudan, the most important parasitic meat-borne infections are Taenia saginata, Toxoplasma gondii, Sarcocystis spp., Linguatula serrata and fish infection with trematode metacercaria. Control measures used in the country to prevent infection with these parasites are through inspecting meat in slaughterhouses for cysticercosis. Toxoplasma and Sarcocystsis infections are not considered during routine meat inspection due to lack of techniques for detection of these infections. Prevalence of infection with these parasites in humans and livestock in all States of Sudan is not available. Methods for routine diagnosis, monitoring or recording of these infections are inadequate, or not existing, in most of the laboratories. Studies are required to establish seroprevalence in livestock and humans. There is an urgent need to monitor and control meat-borne parasites using new technologies such as serological and molecular techniques, health education and vaccination. Researchers are urged to participate and establish innovative ways and means to control these diseases.
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