Evaluation of ImmunoCard STAT test and ELISA versus light microscopy in diagnosis of giardiasis and cryptosporidiosis.

This study was designed to evaluate ImmunoCard STAT Cryptosporidium/Giardia rapid assay and ELISA copro-antigen assays in detecting Giardia lamblia and Cryptosporidium species in fecal samples in comparison to microscopy. Both ImmunoCard STAT and ELISA assays were evaluated with 90 stool specimens that were tested by the standard ova and parasite examination including staining with both iron hematoxylin stain and modified Ziehl Neelson stains. Counting the number of Giardia cysts and Cryptosporidia oocysts in the positive stool samples was done in order to quantify the lower limit of parasite number that was able to be detected by all included assays. Both ImmunoCard STAT and ELISA assays were compared on the basis of the attributes which are number of detected cases, sensitivity, specificity, time required for the procedure and screening, ease of performance and interpretation, and cost. Microscopic examination revealed that 13.3% of the samples were positive for Giardia and 2.2% for Cryptosporidium. By ELISA, 16.7% of the samples were infected with Giardia and 3.3% with Cryptosporidium, while by ImmunoCard STAT, 17.8 and 4.45% of the samples were positive for Giardia and Cryptosporidium, respectively. There is no statistically significant difference between the results of ELISA and ImmunoCard STAT assays. The lowest concentration detected in the stool samples was 10.50 ± 1.05 Giardia cysts and 2.83 ± 1.72 Cryptosporidium oocysts. The ImmunoCard STAT was extremely easy to read, thus requiring much less time, but its cost was much higher than ELISA. We concluded that although the overall ranking of both assays was high, the ImmunoCard STAT rapid assay was a more desirable test despite its higher cost.

Experimental amoebic liver abcess produced by oral administration of Entamoeba histolytica cysts.

To determine the possibility of amoebic invasion and liver-abscess formation Swiss albino mice were infected orally with E. histolytica cysts isolated from human stools. Parasitological and histopathological changes in mice colon and liver tissues were sequentially followed. Three weeks postinfection (p.i) 5% of immunocompetent and all cortisonized immunosuppressed mice passed the parasite in their stools. Only 70% of the latter group of mice sacrificed at that time developed invasive intestinal amoebiasis. At the end of the experiment (12 weeks p.i.) 100% of the remaining immunosuppressed animals developed the same intestinal pathology. Amoebic liver abscess was detected in 62.5% of them. Oral inoculation of E. histolytica cysts constitutes an easy highly reproducible procedure for inducing liver abscess in immunosuppressed mice.

Experimental studies on cyclosporiosis.

Swiss albino mice get Cyclospora infection after orally inoculated with sporulated oocysts. Two weeks post inoculation, most of them passed numerous acid fast immature oocysts in their stools. One week later, light microscopic examination of their intestinal H & E stained sections revealed parasitic stages in a supranuclear location within enterocytes. They were most prominent in the mucosal villi. Lamina propria was expanded by an inflammatory infiltrate. The combined parasitological and histopathological present studies helped in distinguishing Cyclospora which is often confused with Cryptosporidia in stool samples and with Isospora in intestinal sections. Electron microscopy demonstrated both sexual and asexual developmental stages of Cyclospora in ultrathin infected sections. Therefore, Cyclospora species require only a single host to complete its entire life cycle

Is the intestinal tract a portal of entry for Acanthamoeba infection?

Acanthamoeba culbertsoni isolated from a water sample of El-Mahmoudia canal in Alexandria, was orally inoculated into a mouse model (200-400 amoebae/mouse) under different conditions. One week postinfection (P.I.), 20% of infected normoacidic mice and all animals received cimetidine or tetracycline prior to infection passed the parasite in their stools. One month P.I., 70% of cimetidine and 100% of tetracycline pretreated mice showed marked erosion in the intestinal mucosa and areas of necrosis with congestion in the brains, with trophozoites and cysts in both tissues. It is concluded that, normoacidic mice may be simply acting as paratenic hosts. In case of hypoacidity or altered normal flora, the intestinal tract was invaded by amoebae representing a new portal of entry for CNS infection.

Isolation of dust mites from houses of Egyptian allergic patients and induction of experimental sensitivity by Dermatophagoides pteronyssinus.

Six house dust mite (HDM) species were isolated from dust of floors and mattresses of allergic patients houses in Alexandria. Dermatophagoides pteronyssinus (D.p.) was the dominant species in dust of floors and mattresses with average percentages of 68.9% and 78.3% respectively. It was used to induce experimental sensitivity in Swiss albino mice by repeated weekly intranasal instillation of D.p. mites in phosphate buffer saline (PBS). Cytological examination of bronchoalveolar lavage (BAL) fluid of mice revealed prolonged eosinophilia, that peaked on day 28 of the experiment and persisted till the end of the study. Blood eosinophilic counts were progressively increased during the course of the experiment. Histopathological findings showed evident eosinophilic infiltration in nasal and lung tissues of the sensitized mice. Specific IgE response to D.p. was progressively increased, reaching 30 times higher than the control group on day 42. The detected levels of interluekin-4 (IL-4) were in accordance with immunoglobulin response. D.p. provoked severe allergic response and this may help to design an effective therapy to ameliorate such allergic diseases.

A comparison between human, crustacean and bivalve isolates of Microsporidia.

Identification of Microsporidia detected in diarrhoeic stool of human and from press preparation of crabs, and bivalves muscles was done by staining with Giemsa, modified trichrome and H & E stains respectively. Positive samples were isolated & used for infection of 3 groups of mice viz group A human isolate, group B crab & group C bivalve isolates. Parasitological and histopathological studies using light and transmission electron microscopy (TEM) were done for samples from each group. The results clarified that human, crab & bivalve Microsporidia isolates showed common features. They were found in the supranuclear region of enterocytes. The stages observed were meronts, sporonts and free spores. Each spore was 1-2 um in length containing a single nucleus, a vacuole and a polar filament. Further genetical and biochemical studies will be undertaken to confirm the similarity or differences between these isolates.

Studies on experimental mixed infection of Schistosoma haematobium and Schistosoma mansoni.

Swiss Albino mice have been infected with S. haematobium and challenged 4 weeks later with S. mansoni. Parasitological, pathological and ultrastructural studies were done. The results revealed cross mating between the two species. A reduction in S. mansoni worm load, egg count, hepatic granuloma number and size was noticed. The presence of heterologous immunity was suggested.

Electroencephalographic changes in rats received antigens of different parasites.

The prevalence of epilepsy in developing countries is much higher than in developed ones. Some of the highest prevalence rates in developing countries have been reported from tropical Africa where parasitic infections are endemic. This work was carried out to assess the effect of different parasitic antigens on the activity of cerebral cortex in rats. Nine crude antigens were used: Adult Fasciola, adult S. mansoni, hydatid cyst, T. spiralis, E. histolytica, Acanthamoeba spp. G. lamblia, Cryptosporidium spp. and crude antigen of T. gondii. All the parasitic antigens induced electroencephalographic changes compared with baseline tracings.

Effect of ivermectin on combined intestinal protozoal infection (giardiasis and cryptosporidiosis).

Ivermectin, a broad spectrum antiparasitic agent has become a promising drug for treating parasitic infection and infestation. This study was carried out to investigate its activity against two common protozoal infection, giardiasis and cryptsporidiosis in a rat model. The results of this study showed that ivermectin therapy is effective against both parasites at a dose of 200 micrograms/kg.

The possibility of congenital infection with Acanthamoeba culbertsoni.

Acanthamoeba culbertsoni is one of the free-living amoebae which are known to be pathogenic to man, causing granulomatous amoebic encephalitis (GAE). In this study, Acanthamoeba culbertsoni was isolated from a water sample of El-Mahmoudia Canal in Alexandria, in July-1993. This was used to infect mice intranasally to study the histopathological picture of the brain and lungs. The neuropathological features consisted of chronic granulomatous encephalitis in which cysts and trophozoites were found. Associated Acanthamoeba pneumonitis with massive consolidation was also observed. Congenital infection of offsprings was reported for the first time in this study.

Serum IgG antibody response to Pneumocystis carinii among immunosuppressed, malnourished and healthy rats.

Pneumocystis carinii is an important opportunistic pulmonary pathogen that causing pneumonia in premature infants, children with immunodeficiency diseases and patients of all ages receiving immunosuppressive agents. In this work, humoral immune responses to this organism were studied, using IFAT during the period of infection and recovery of immunosuppressed and malnourished rats compared to healthy group. Where sever pneumonitis similar to that seen in humans can be induced in this experimental model. Serum IgG antibody titers to the organism were absent in rats administered corticosteroids but rose after steroid tapering with disappearance of the organism from their lungs due to reactivation of the immune system. While in malnourished infected rats, clearance of the organism had occurred after regaining the protein diet with progressive increase in IgG level denoting their immunocompetent state. IgG antibody appeared in the serum of control healthy rats with the progress of age at low non diagnostic level indicating the presence of dormant parasites in their lungs.

Opportunistic intestinal protozoa in chronic diarrhoeic immunosuppressed patients.

Chronic diarrhoea accompanied by weight loss is a common and often debilitating problem in immunocompromized patients, receiving chemotherapeutic agents. In these patients, the intestinal opportunistic parasites probably played a major role in causing this clinical manifestation. The present work, aims to search for these parasites. Special stains for each parasite were used to differentiate it easily from the fecal elements, obviating the need for diagnostic invasive techniques especially used in microsporidial infection. The detected parasites were, Giardia lamblia (17.7%) best seen by iron haematoxylin stain. Coccidian oocysts (Cryptosporidia; 13.3% Isospora belli; 2.2%) were clearly seen by using Ziehl-Neelsen and Chromotrope-based stains. The Gram positive spores of Enterocytozoon bieneusi were (4.4%) and best seen by using chromotrope-based stain, where as Giemsa failed in their diagnosis.

Topical application of ivermectin for human ectoparasites.

Ivermectin is used in veterinary practice against many ectoparasites and endoparasites and is the drug of choice for treatment of human onchocerciasis. This study was carried out to investigate the effect of topical application of this drug against human ectoparasites (Sarcoptes scabiei and Pediculus humanus capitis). Ivernectin was found to have a curative effect on head lice after a single topical application. In patients with scabies, the drug was also found to be effective after a single application. However, in 50% of the cases, another application was needed five days later.

Aminosidine sulphate in experimental giardiasis.

Giardia lamblia infection may be asymptomatic or may produce diarrhea with or without malabsorption. Many drugs were used for treatment of giardiasis, but none proved to be ideal since all have potential troublesome side effects as they are absorbed from the intestine. In this study, a locally acting drug aminosidine-sulphate (gabbroral) has been tried in treatment of experimental giardiasis in a rat model under different conditions of gastric acidity which is one of the main local factors affecting the pathogenicity of the organism. The best results were obtained in the group with hyperacidity which was induced by indomethacin (indocid) with significant improvement in the pathological picture and parasitic count. While in experimental animals with normal acidity there was only partial eradication of the parasite. However, in the group with hypoacidity induced by cimetidine (cimetex), the drug showed no beneficial effects since most organisms invaded the deeper layers of the intestine escaping the local action of the drug.

Isolation and identification of free-living amoebae from some water sources in Alexandria.

Samples from different water sources of Alexandria, and from nasal passages of 500 healthy children inhabiting areas nearby these sources were examined for the presence of free-living amoebae. These samples were cultured on 1.5% non nutrient agar streaked with bacteria. Amoebae were isolated and identified by means of their morphological characters and ability to produce flagellated forms. Characteristics of the cystic stages and pattern of excystation also aided in the identification of the various species. Nine species, Naegleria gruberi, N. fowleri, Acanthamoeba rhysodes, A. glebae, A. culbertsoni, A. astronyxis, A. palestinensis, V. avara and V. inornata were isolated from the water of canals and drains. N. gruberi and A. rhysodes were found in the nasal passages of six healthy children living near the contaminated canals. No amoebae were encountered in the drinking water, swimming pools, sea and lake water included in this study.

Pneumocystis carinii: recognition of the infection in albino rats using different stains.

Pneumocystis carinii is a commensal protozoan which may cause pneumonia in hosts with compromised immune status and may end fatally. Since effective management of pneumocystic pneumonia depends on rapid and accurate recognition of the disease, so, the present study aims to throw lights on the best staining method for cytodiagnosis of this organism with the sequential pathological changes in the infected lungs. An immunosuppression state was induced in albino rats for 6-8 weeks then rats were sacrificed weekly & lungs were examined for infection using different stains. In stained smears, intracystic bodies have been identified using Giemsa, Papanicolaou & Toluidine blue stains. On the other hand, cysts were inspected in paraffin sections using Gomori methenamine silver nitrate (GMS) & weight gram stains. Histopathologically, in sections stained with H & E, features of Pneumocystis carinii pneumonia were obvious, foamy exudation, inflammatory infiltration formed mainly of histiocytes, plasma cells, lymphocytes, thickening of alveolar septa and lastly formation of hyaline membrane in some alveoli.