utility of direct agglutination [DAT] and fast agglutination screening [FAST] tests in serodiagnosis of experimental microsporidiosis

The present study was designed to evaluate the efficiency of two serodiagnostic tests; the direct agglutination test [DAT] and the fast agglutination screening test [FAST] in the diagnosis of Microsporidia in experimentally infected mice and to differentiate between different species of the parasite. The swiss albino mice were divided into non infected control and infected experimental groups which were further subdivided into ten subgroups. Ten samples of microsporidial spores were isolated from ten human stools and each one was used to infect each subgroup of mice. Stool and sera were collected weekly from each subgroup from the 1[st] to the 4[th] week post infection [PI]. DAT and FAST tests, using antigen prepared from the different species of microsporidial spores were used to detect antibodies in sera of different mice subgroups. The cross reactivity of microsporidial spores with the antibodies of Cyclospora cyatenensis and Cryptosporidium parvum was investigated by DAT and FAST. The results proved that DAT and FAST were effective in detecting microsporidial antibodies in sera of experimentally infected mice from the 2[nd] week PI till the end of the study, without cross reactivity with C. cyatenensis or C. parvum. They failed to differentiate between different Microspoiridia species used but, they gave good interpretation and they were specific and sensitive, and did not need sophisticated equipments

Effect of solar disinfection on viability of intestinal protozoa in drinking water

The effect of solar disinfection on the viability of intestinal protozoa Giardia lamblia, Microsporidia sp., Cryptosporidium parvum, Cyclospora cyatenensis and Entamoeba histolytica in drinking water was studied as compared to chlorine disinfection. The protozoa were collected from stool samples, to infect to the distilled water. Chlorinated water samples were prepared at concentration of 4 ppm, and the parasites were incubated overnight at room temperature with the treated water. Sun treatment was applied for 2 exposures [6 and 24 hrs], in summer and winter. Sun treated water samples were put in tubes and exposed to sun. The 2 disinfection methods were tested in plastic and glass test tubes. Parasites viability was assessed by viability assay using trypan blue stain [0.4%], and bioassay infectivity tests in experiment-tally laboratory bred mice. Results proved that all parasites' viability was not affected by chlorine, following solar disinfection treatment, parasites became dark blue in colour and deformed by trypan blue stain. High parasites death was recorded for all parasites except Microsporidia sp. Bioassay infectivity test showed a statistically significant reduction in mean number of all parasites in intestinal sections compared to controls. The best results were tubes exposure to sun for 24 hrs in summer, where G. lamblia, C. parvum and C. cyatenensis were inactivated or absence in intestinal sections. No statistically significant difference was between the use of plastic and glass tubes, either in chlorine or sun treated parasites. So, solar disinfection proved a simple, cheap and effective means for improving water for human use, particularly in developing countries

Immunization against trichinellosis using microwaved larvae of trichinela spiralis

The present study evaluated the effect of microwave irradiation on infective larvae of Trichinella spiralis [T. spiralis] by the ultrastructure changes of the microwaved larvae [ML] using scanning electron microscope [SEM]. The ML tested the ability to immunize mice against a challenge infection with T. spiralis. For the optimal dose and the best route of immunization inducing protection against challenge infection, two doses were used; 300 and 600 ML as one or two-dose regimen, each dose was given orally and intraperitoneally [IP]. SEM revealed tegumenttal damage of the ML in the form of distortion, loss of normal fold pattern and depressions or papillae protruded from their outer surface. After administration of the ML [orally or IP] to the non-infected control mice, neither adults nor larvae were detected in the intestines or muscles respectively. This indicated loss of larvae infectivity after exposure to the microwave irradiation. Also, a significant protection against challenge infection with T. spiralis was demonstrated in experimental mice immunized by ML, orally or IP. This was assessed by a statistically significant decrease in adult and muscle larval count, compared with the non-immunized infected control. Complete protection against both adults and larvae [100%] was achieved by IP injection of two doses of 600 ML, two weeks apart. The results suggested the feasible application of the microwave irradiation on meat for its decontamination from T. spiralis larvae. Such a method might be a promising a prophylaxis vaccine against trichinellosis in animals and/or humans

Effect of Schistosoma mansoni infection on physiological gastrointestinal transit and contractility

Schistosoma mansoni [S. mansoni] is a major health problem; a large proportion of infected individuals suffer from motility-related gastrointestinal disturbances. However, the exact relationship between the gastrointestinal motility changes, the enteric nervous system neuronal excitability, and the complexity of the resulting symptoms, in both the acute and chronic phases of inflammation are still not clear. The work was designed to investigate the effect of two different intensities of S. mansoni infection on gastrointestinal transit and contractility of the colonic muscles, in both acute and chronic phases of inflammation of experimentally infected mice; and to asses the relation between gastrointestinal transit, contractility, and serum antigen and antibody levels. The study was conducted on 60 mice divided into 2 groups a control group consisting of 12 mice, and S. mansoni infected group consisting of 48 mice. The infected group was further subdivided into two subgroups, each infected by a different intensity of cercaria [50 and 200 cercaria/mouse]. Gatrointesintal transit and contractility were recorded from the colon of each group and were analyzed at the acute [8[th] week] and chronic phase [12[th] week] of inflammation. In addition, the immunological changes of the host were assessed in both infected subgroups of mice, at the same studied durations. At 8weeks postinfection, in both infected subgroups, gastrointestinal transit was significantly decreased, in concurrent with significant increase in the colonic muscle contractility, compared to the control group. At that time, the serum antigen was absent, while the serum antibody was detectable at low titre. However, at twelve weeks postinfection, there was a further statistically significant decrease in gastrointestinal transit, and increase in the colonic muscle contractility. These alterations were coinciding with absence of serum antigen and increase in the antibody titre. All changes were more pronounced in the second infected subgroup [200 cercaria/mouse] than the first infected one [50 cercaria/mouse], Indicating that the increased host immunity at the 12[th] week postinfection did not improve the motility disorder of the colon. We conclude that intestinal schistosomiasis is associated with disturbances in gastrointestinal transit and contractility, which are related to the time course and the intensity of the infection, and may be involved in the pathogenesis of the motility disorder associated with the disease. The hypercontractility in the acute phase can be explained by functional changes in the excitability of enteric nervous system neurons due to the release of mediators, and in the chronic phase due to granuloma formation leading to structural changes in the enteric nervous system. Elucidation of the mechanism whereby inflammation alters enteric nervous control of gastrointestinal function may lead to novel treatments of motility disorders of the disease

Experimental trichinosis: parasitological, electrophysiological and biochemical studies

Trichinosis is a parasitic infection affecting the gut and the muscles causing mild gastrointestinal symptoms followed by periorbital oedema, muscle pains, fever and eosinophilia. The infection evokes functional disturbances in physiological effector systems. Furthermore, several biochemical changes are associated with the infection. Therefore, this work was carried out to study the electrophysiological changes in intestine, striated and cardiac muscles by electromyography [EMG] and to assess the biochemical changes through measurement of serum cholinesterase and intestinal myeloperoxidase activity [MPO] in both light and heavy infected experimental animals by Trichinella spiralis [T. spiralis]. Electrophysiological results showed increased contractility of the smooth muscle layers of the intestine only early in the infection, whereas both striated and cardiac muscles showed increase in the contractility with the progress of infection in both light and heavy infection. Significant myocardial dysfunction in the form of bradycardia, in addition to major histopathological changes in the heart occurred from the beginning of the infection and increased till the end of the study. Biochemical study showed gradual increase in serum cholinesterase, while, the intestinal MPO showed increase only in the early stage of the infection. It was noticed that all changes were more pronounced in the heavily infected group than the lightly infected one

use of ELISA and immunohistochemistry techniques for detection of toxoplasma gondii antigen in tissues of experimentally infected mice

The capability of double antibody sandwich enzyme-linkad immunosorbent assay [ELISA] for detecting antigens of Toxoplasma gondii [T. gondii] in different mice tissue specimens was evaluated in comparison to the immunohistochemistry [IHC] technique. Results proved that tissue antigens were detectable in liver, kidney and mesenteric lymph node [LN] specimens by both methods from the second day of infection, with statistically significant increase in its amount in all organs throughout the period of the study. Using ELISA technique, the highest antigen level was recorded on the second day [0.120 +/- 0.0015] and the fourth day [0.147 +/- 0.0034] of infection in LN specimens, while, the liver showed the highest antigen level at the sixth day post infection [PI][0.165 +/- 0.0066]. On the other hand, using the IHC technique, the highest number of tachyzoites was recorded in LN sections in all studied durations, the second, the fourth and the sixth days PI [1.1 +/- 0.875, 1.6 +/- 1.173 and 3.1 +/- 1.370 respectively]. Thus, sandwich ELISA technique might offer a valuable aid for rapid diagnosis of acute toxoplasmosis in human tissues, and it has proved to be more accurate than IHC technique, since its results was coincided with the pathogenesis of the disease.

Effect of schistosome mansoni infection on physiological gastrointestinal transit and contractility

The work aimed to study the effect of Schistosoma mansoni [S. mansoni] on gastrointestinal transit and contractility of the colonic muscles of two subgroups of experimental mice, in-faceted by 50 and 200 cercaria/mouse respevtively, at 8th and 12th week postinfection [PI]. In addition, the histopathologic changes in the colon, and the immunological changes of the host were studied at different durations. At 8th weeks PI, in both sub-groups, gastrointestinal transit was statistically significant decreased, in concurrent with statistically significant increase in the colonic muscle contractility compared to the controls. The colon was inflamed as shown by mucosal inflammatory infiltrates, with large size and number of schistosomal granulomas. The se-rum antigen was absent, while the serum antibody was detec-table at low titre. At 12th weeks PI, there was a more statistically significant decrease in gastro-intestinal transit, and increase in the colonic muscle contractility. The colon was still inflamed, but the granulomas were reduced in size and in number, with increase in the fibrocytes density. These alterations coincided with absence of serum antigen and increase in the antibody titre. All changes were more pronounced in the 2nd group of mice [200ceraria/mouse] than the 1st one [50cercaria/mousa]. So, intestinal schistosomiasis is associated with great structural, functional and immunological changes, related to the time coursa and the infection intensity which may be involved in the pa-thogenesis and clinical manifestations of the disease.