Animal model Balamuthia mandrillaris CNS infection: contrast and comparison in immunodeficient and immunocompetent mice: a murine model of "granulomatous" amebic encephalitis.

Balamuthia mandrillaris and several species of Acanthamoeba are pathogenic "opportunistic" free-living amebas which cause granulomatous encephalitis (GAE) in humans and animals. The granulomatous component is negligible or absent, particularly in immunocompromised individuals. GAE is an "opportunistic" infection, usually seen in debilitated, malnourished individuals, in patients undergoing immunosuppressive therapy for organ transplants, and in Acquired Immunodeficiency Syndrome (AIDS). From around the world 156 cases of GAE have been reported from 1956 through October 1, 1995, 59 (26 in the USA) of them caused by B. mandrillaris, at least seven of them in AIDS patients. The present study was designed to compare and contrast the susceptibility of infection, the rate of infectivity and the histopathological changes within the CNS between the mutant, severe combined immunodeficient mice (SCID) infected with B. mandrillaris and the normal immunocompetent BALB-C mice. The SCID mouse is severely deficient in B and T lymphocytes, therefore lacking immunoglobulin and cell-mediated immunity. This mouse is also prone to develop early T cell lymphomas. One thousand amebic trophozoites and cysts of B. mandrillaris were intranasally and intraperitoneally inoculated in both strains in mice. Seventy percent of the intranasally inoculated SCID mice died due to CNS infection. Amebic trophozoites and cysts were found within CNS parenchyma without inflammatory response. Death occurred from 2 to 4 weeks after inoculation. By contrast only 10 percent of the intranasally inoculated BALB-C mice died with CNS infection showing the characteristic features of GAE. None of the intraperitoneally inoculated mice developed amebic infection. The SCID and BALB-C mice were logical models to study the structural alterations within the CNS of B. mandrillaris infection. This animal model recapitulates with excellent degree of fidelity several aspects of the pathogenesis and histopathological features of free-living amebic infection in human beings.

Diagnosis of toxoplasmosis in bone marrow transplant recipients: comparison of PCR-based results and immunohistochemistry.

Toxoplasmosis in bone marrow transplant recipients is a rare but serious complication and if untreated, almost uniformly fatal. The diagnosis, however, remains difficult. We therefore compared serial determination of antibody titers specific for T. gondii before and after transplantation, serial PCR for T. gondii DNA in serum, PCR and nested PCR for T. gondii DNA in various tissues, conventional histology and immunohistochemistry for detection of parasites in three patients with autopsy-confirmed toxoplasmosis after bone marrow transplantation. Immunohistochemistry demonstrated the presence of parasites in 13 out of 20 organs investigated (65%), whereas PCR detected T. gondii-specific DNA in 15 out of 20 organs (75%). Immunohistochemistry revealed concordant results to PCR data in 60% of the specimens. With the use of a nested PCR protocol, eight out of nine samples (89%) were positive for T. gondii-specific DNA. The combination of both methods detected the presence of parasites in 90% of the specimens. Serial PCR in serum did not yield positive results. Neither PCR nor immunohistochemistry was able to detect parasites in all organs investigated, but both methods together improved sensitivity to 90% and consequently, should be used jointly to maximize diagnostic precision. Bone Marrow Transplantation (2000) 25, 1257-1262.

Quantitative detection of Toxoplasma gondii DNA in human body fluids by TaqMan polymerase chain reaction.

OBJECTIVE: A new quantitative polymerase chain reaction (real-time PCR) was designed to detect Toxoplasma DNA in human body fluid samples. METHODS: Real-time fluorescence detection of amplification product formation on the basis of the TaqMan-System was established with Toxoplasma 18S rDNA as a target gene. RESULTS: The method provides a high sensitivity comparable to conventional nested PCR procedures and generates quantitative data when detecting toxoplasmic DNA in human blood, cerebrospinal or amniotic fluid. Moreover, data were obtained investigating blood samples from an immunocompromised patient with reactivated toxoplasmosis after allogeneic bone marrow transplantation, monitoring the therapeutic effect. CONCLUSIONS: The potential application of this method to detect Toxoplasma DNA in body fluids and to follow the development of parasitemia under therapy could be demonstrated.

Nitrocellulose dot-ELISA for serodiagnosis of schistosomiasis.

The diagnostic value of the nitrocellulose (NC)-ELISA technique originally described for the detection of viral and bacterial antigens was studied for the detection of antibodies in patients with parasitologically confirmed schistosomiasis, using only about 100 ng total protein content per NC disc of Schistosoma mansoni soluble egg antigen supplied by WHO. The results showed excellent sensitivity: 100% (38/38) for S. mansoni cases and 93.6% (44/47) for S. haematobium. The specificity tested on 50 sera of persons from non-endemic areas was also 100%. 34 sera of patients suffering from other parasitoses were also included. 3 sera of 10 from filariasis cases reacted positively by NC-ELISA, but they were also positive by indirect immunofluorescence, indicating a possible undetected Schistosoma infection. One positive reaction among sera from 4 toxocariasis cases was not confirmed by further tests. We conclude that the NC-ELISA can be a useful technique, especially in developing countries where tests with low cost equipment are needed. Large-scale screening studies should be done to evaluate its usefulness under field conditions.

Immunity to Acanthamoeba culbertsoni: experimental studies with Acanthamoeba and control antigen preparations.

Mice were intranasally immunized with living and killed Acanthamoeba as well as culture supernatant, living Toxoplasma and BCG, and challenged with pathogenic A. culbertsoni strain A-1. The best protection was achieved with killed amoebae of the same strain. A high rate of mortality was observed in immunized mice treated with immunosuppressives and challenged with A. culbertsoni A-1. The significance of the results in relation to environmental human infection is discussed.

Extracerebral toxoplasmosis in AIDS. Histological and immunohistological findings based on 80 autopsy cases.

Despite the great amount of literature concerning toxoplasmic encephalitis in AIDS patients, little is known about extracerebral toxoplasmosis. Therefore we conducted a study of 80 autopsy cases to estimate the frequency of extracerebral toxoplasmosis. A control group of 50 cases was completely negative for all markers applied. In 35 of the 80 AIDS-cases (43.7%), organisms could be detected. In 13 cases (16.2%) there was an extracerebral toxoplasmosis; 4 cases (5%) showed only extracerebral involvement and in 9 cases (11.2%), extracerebral toxoplasmosis occurred in combination with cerebral manifestations. In 22 cases (27.5%), only cerebral toxoplasmosis was found. The following organs were involved: cardiac muscle (15%), lungs (6.2%), liver (5%), pancreas (5%), gastrointestinal tract (6.2%), adrenal glands (5%), lymph nodes (5%) and testis (3.7%). In individual cases further organs, not mentioned above, were involved. Pseudocysts could be demonstrated within necroses and inflammatory foci by conventional staining, whereas trophozoites became apparent only immunohistologically.

Visceral leishmaniasis mimicking a flare of systemic lupus erythematosus.

Fever in systemic lupus erythematosus (SLE) may be caused by exacerbation of the disease itself or by infection. We report on a patient with a long standing history of SLE that was complicated by fever and pancytopenia with no splenomegaly. SLE disease activity was suspected because of an elevated DNA-antibody titer. The early positive response to corticoid therapy may have masked the underlying infection. Visceral leishmaniasis was diagnosed by a repeated bone marrow biopsy and serological testing.

Serodiagnosis of bovine besnoitiosis by ELISA and immunofluorescence tests.

Sera from non-infected cattle and cattle infected with Anaplasma, Babesia, Theileria and Sarcocystis were tested for antibodies to Besnoitia in ELISA and immunofluorescence tests (IFT) with Besnoitia besnoiti of blue wildebeest origin as antigen. Only 2 out of 86 sera gave false positive reactions in ELISA and none in the IFT, indicating a high specificity for the tests. Three-hundred-and-three bovine sera from 3 farms in an area endemic for besnoitiosis were similarly tested and the results were correlated with clinical findings based on visual inspection for typical symptoms and the presence of cysts in the scleral conjunctiva. Most of the positive tests were observed in cattle older than 1 year. Of the cases with scleral cysts, 68,7% were positive in the ELISA and 81,74% in the IFT. However, 45,74% (ELISA) and 49,47% (IFT) of the clinically negative cattle were clinically positive, indicating a high incidence of clinically inapparent infection. These results indicate a relatively low sensitivity for these serological tests. An unexpected finding was that the ELISA remained negative for at least 60 days after experimental infection of the cattle, the maximum period for which tests were done, whereas the IFT became positive. No antibodies against B. besnoiti could be found in human sera. Besnoitia jellisoni antigen gave positive results with B. besnoiti antibodies in ELISA, but not in the IFT.

Serodiagnosis of parasitic infections by ELISA with different antigens.

An enzyme-linked immunosorbent assay is described in which four antibodies (amoebiasis, schistosomiasis, echinococcosis and filariasis) can be tested at once. Because of the sensitivity, specificity, reproducibility and practicability this test system can be recommended as a quantitative routine test.

Comparison of three DOT-ELISA techniques in diagnosing Schistosoma haematobium infection.

The DOT-STRIP-ELISA was evaluated in the laboratory as a serodiagnostic tool for Schistosoma haematobium infection in order to assess the potential of introducing the technique under field conditions in the developing world. Out of 100 individuals with parasitologically confirmed Schistosoma haematobium, 87 reacted positively (sensitivity 87%), whereas 45 out of 50 sera from individuals from a non-endemic area reacted negatively (specificity 90%). Results were reproducible. Cross-reactions were observed with sera from individuals infected with Schistosoma mansoni, Echinococcus, Leishmania and Wuchereria. The DOT-STRIP-ELISA offers more advantages with regard to practicability and test-time when compared with the DOT-DISC-ELISA and DOT-MILLIPORE-ELISA.

Pränatale Übertragung der Toxoplasmen von der Mutter auf das Kind.

A report is given on the infection of pregnant women with Toxoplasma and on the laboratory diagnosis on mother, fetus and newborn. The next chapters deal with the consequences for the child and its chemotherapy. Prevention and problems of mother care are discussed in detail, as well as the infection as a notifiable one.

[Parasitic zoonoses]. / Parasitäre Zoonosen.

A review is given on Cryptosporidiosis, Giardiosis, Toxoplasmosis, Toxocarosis, Trichinellosis and Taeniosis.

[The detection of Toxoplasma gondii in abortion tissues of sheep using the polymerase chain reaction]. / Der Nachweis von Toxoplasma gondii in Abortgeweben vom Schaf mittels der Polymerase-Kettenreaktion.

A polymerase chain reaction was applied to detect Toxoplasma gondii DNA in placental and fetal tissue samples of 47 unselected ovine abortions of the lambing season 1990/91 (Baden-Württemberg, Rhineland, Hesse). For the amplification a 190 bp or 223 bp sequence of the B1-gene of T. gondii was selected as the target sequence. Both sequences were detected in five abortions. All positive results were immunohistochemically confirmed using the peroxidase antiperoxidase technique (PAP-staining). Thus, in Germany, too, T. gondii infection in sheep during pregnancy should be considered as a possible cause of abortions, particularly in case of abortions of unknown genesis.

Prevalence of Echinococcus granulosus in some selected sites of Ethiopia.

This study assesses the current prevalence status of Cystic echinococcosis in cattle and sheep and echinococcosis in dogs in Assela, Makale and Debre Zeit areas of Ethiopia. Our target areas represent three different agro-ecological zones in Ethiopia. Of the cattle studied the infected were, 17(13.4%) in Assela, 20(23.3%) in Makale, and 3(10%) in Debre Zeit haboured at least one fertile Hydatid cyst. Among the sheep, 23(59%) haboured fertile cysts and no goat was found to have fertile cysts. There was a significant difference in the percentage of infected sheep with fertile cysts from the same group of cattle originating from the three study areas. The percentage fertility of the total cysts examined were 4.2%, 6.8% and 5.5% in Assela, Makale and Debre Zeit respectively. Out of this 56.5% was from Assela, 65.4%, Makale and 66.7% from Debre Zeit were viable. From the sheep examined, 43.6% had fertile cysts with viability of 90.7%. The lung was the most affected organ in both species. A total of 44 dogs, 14 from Assela, 15 from Makale, and 15 from Debre Zeit were examined for canine echinococcosis. The prevalence of the infection was 7(50%) in Assela, 3(20%) in Makale and 5(33.3%) in Debre Zeit. There was no significant difference between these prevalence rates although noticeable differences in the worm burdens among the three areas were observed.