Ultrastructural Changes in Cryptosporidium parvum Oocysts by Gamma Irradiation

Cryptosporidium parvum is known as one of the most highly resistant parasites to gamma irradiation. To morphologically have an insight on the radioresistance of this parasite, ultrastructural changes in C. parvum sporozoites were observed after gamma irradiation using various doses (1, 5, 10, and 25 kGy) following a range of post-irradiation incubation times (10 kGy for 6, 12, 24, 48, 72, and 96 hr). The ultrastructures of C. parvum oocysts changed remarkably after a 10-kGy irradiation. Nuclear membrane changes and degranulation of dense granules were observed with high doses over 10 kGy, and morphological changes in micronemes and rhoptries were observed with very high doses over 25 kGy. Oocyst walls were not affected by irradiation, whereas the internal structures of sporozoites degenerated completely 96 hr post-irradiation using a dose of 10 kGy. From this study, morphological evidence of radioresistance of C. parvum has been supplemented.

A survey of cryptosporidiosis among 2,541 residents of 25 coastal islands in Jeollanam-do (Province), Republic of Korea

In order to determine the distribution and prevalence of human cryptosporidiosis on western and southern coastal islands of Jeollanam-do (Province), fecal samples were collected from 2,541 people residing on 25 islands, 13 in the western coasts and 12 in the southern coasts, during July and August 2000. Fecal smears were prepared following formalin-ether sedimentation of the samples and stained by a modified acid-fast procedure. The presence of Cryptosporidium oocysts was determined by light microscopy. Cryptosporidium oocysts were detected in 38 specimens (1.5%). The oocyst positive rate varied (0-6.0%) according to island; the highest was detected on Oenarodo (6.0%), followed by Naenarodo (5.6%) and Nakwoldo (5.4%). The majority (35 persons, 94.6%) of Cryptosporidium-infected individuals were older than 50 years of age. Men (22/1,159; 1.9%) were infected at a higher rate than women (16/1,382; 1.2%). The results of the present survey indicate that human Cryptosporidium infections (due to Cryptosporidium hominis and/or C. parvum) are maintained at a relatively low prevalence on coastal islands of Jeollanam-do, Republic of Korea.

Testing methods for detection of Cryptosporidium spp in water samples.

A large waterborne outbreak of cryptosporidiosis in Milwaukee, Wisconsin, USA in 1993 prompted a search for ways to prevent large-scale waterborne outbreaks of protozoan parasitoses. Methods for detecting Cryptosporidium parvum play an integral role in strategies that lead to appropriate treatment of surface water, but are criticized because they produce results that are highly variable. The US Environmental Protection Agency developed a set of criteria to evaluate detection methods for protozoan parasites in water. As a consequence, the Agency has had to develop approaches to reducing uncertainty of evaluations. The variability and accuracy of various methods of producing small numbers of Cryptosporidium spp oocysts were tested. The least variable and most accurate method was used to spike seven surface water, and one tap water sample to compare 4 detection methods that had been reported in the literature. The least variable and most accurate method for spiking specified numbers of oocysts into samples was found to be flow cytometry. The most effective of the methods tested for detection in surface, tap and reagent water was solid phase cytometry.

Inactivation of Cryptosporidium parvum oocysts in field soil.

Cryptosporidium parvum oocysts from dairy calves are believed to regularly contaminate watersheds. Identifying oocysts and measuring their viability in the natural environment are important elements in estimating the risk posed by this resistant organism. A 152 day field study was conducted to measure the viabilities of oocysts inoculated into 25 sampling points. Water potential, pH, and ammonium content were also measured at the same 25 sampling sites. A three-dimensional mapping program (Surfer) was used to create 3-D maps of the viabilities of C. parvum oocysts and other factors measured during the experiment. The results indicate that 3-D graphical presentation may be a useful means to identify potential sites of greatest risk of oocyst survival and could indicate areas where natural conditions are causing the most rapid oocyst inactivation, and this method can be a means for the future measurement of microorganism inactivation in the natural environment.

Cryptosporidium parvum--propagation of oocyst in neonatal calves.

Shedding of Cryptosporidium parvum oocyst was studied in experimentally infected Jersey-Sindhi cross bred calves. Three 7 day old bull calves housed in isolation were orally infected with 10(8) oocysts of Cryptosporidium parvum. The prepatent and patent period of the experimental infection were 5 and 4 days respectively. Maximum oocyst output [2 x 10(5) oocyst per gram (OPG) was observed on the 7th day post inoculation (PI). The mean total oocyst output was 2.5 x 10(7). Diarrhoea started on the second day of oocyst shedding.

Criptosporidiose experimental em bezerros neonatos em Goiânia-Go / Experimental bovine cryptosporidiosis in neonate calves in Goiânia-Go

A caracterização da criptosporidiose experimental foi feita através da avaliação clínica eliminação de oocistos nas fezes e lesões à necrópsia. Foram inoculados 4 bezerros mestiços zebu x holandês identificados com bezerro 1 (8 dias de idade), 3 (1 dia de idade) e bezerro 4 (1 dia de idade), provenientes da Escola de Veterinária da UFG. Os três primeiros bezerros foram inoculados com uma suspensão de fezes contendo (dez elevada a quinta potência) oocistos de C. parvum. O quarto bezerro foi inoculado com o mesmo volume da suspensão, porém com concentração de oocistos desconhecida. Para caracterizar as alterações histológicas e o desenvolvimento endógeno foram inoculados dois bezerros com (dez elevada a quinta potência) oocistos de C. parvum. Os animais eram mestiços zebu e holandês com um dia de idade. O período patente da infecção foi mais ou menos uniforme para os animais 1,2, e 3 com eliminação de oocistos nas fezes em torno do oitavo e nono dias e para o bezerro 4 este período foi menor com a eliminação durante quatro dias. As observações microscópicas dos cortes histológicos revelaram que as formas endógenas do C. parvum, se encontram distribuídas no Intestino delgado, concentrando-se no Íleo na porção distal do terço posterior. A observação microscópica dos fragmentos teciduais da porção posterior do íleo mostrou numerosas formas de Cryptosporidium parvum, sobre o pólo superior das células colunares ao longo das vilosidades. Observou-se ainda descamação do revestimento epitelial em vários pontos