The risk of Strongyloides stercoralis transmission from patients with disseminated strongyloidiasis to the medical staff.

To assess the risk of Strongyloides stercoralis transmission from two patients with disseminated strongyloidiasis to medical staff who had been in close contact with the patients, blood and stool specimens were obtained from medical staff two to three months after close contact with the patients. Antibodies to S. stercoralis were determined in blood. Stool specimens were tested for parasites with three different procedures.Forty-one medical staff were included. Culture and stool examination were negative in all subjects. Serology was negative in all subjects but one who had a borderline titer without signs or symptoms of strongyloidiasis. No evidence of transmission of S. stercoralis from patients with disseminated strongyloidiasis to medical staff was found.

Screening for nucleotide variations in ribosomal DNA arrays of Oesophagostomum bifurcum by polymerase chain reaction-coupled single-strand conformation polymorphism.

We exploited the high resolution capacity of polymerase chain reaction (PCR)-coupled single-strand conformation polymorphism (SSCP) to screen for sequence variation in the second internal transcribed spacer (ITS-2) of ribosomal DNA (rDNA) among 77 individuals representing Oesophagostumum bifurcum from human or Mona monkey hosts from Africa. SSCP analysis revealed distinct profiles among some of the individuals, and sequence analysis of representative samples defined different ITS-2 sequence types attributable to polymorphism at particular nucleotide positions. However, there was no unequivocal sequence difference between O. bifurcum individuals from humans and that from monkeys. This provided some support for the hypothesis that the parasite from the two hosts represents a single species and that the sequence microheterogeneity detected in the ITS-2 rDNA region represents population variation, although the findings were insufficient to reject the proposal that the parasite represents different species. Overall, the results showed the usefulness of the SSCP-sequencing approach for studying the genetic variation in O. bifurcum populations and indicated its potential to study macromolecular evolution and elucidate population differentiation at the molecular level.

The impact of the composition of the bone marrow graft on engraftment and graft-versus-host disease.

To study the impact of the composition of the bone-marrow graft on engraftment and graft-versus-host disease (GvHD), we analyzed the data on 29 patients with acute leukemia in remission and 11 patients with aplastic anemia. All of them received bone-marrow grafts from HLA matched, MLC nonreactive, sibling donors, were nursed in laminar down-flow isolators with selective gut decontamination, and received GvHD prophylaxis with methotrexate. The number of nucleated cells in the marrow graft/kg body weight of the recipient had no relation with the rapidity of engraftment or with the occurrence and severity of GvHD. The number of hematopoietic progenitor cells (CFUc)/kg had a weak, but significant, correlation with both the number of neutrophils at day 30 post BMT and with the day at which the reticulocytes passed the 10% level. The number of T cells/kg did not show any correlation with either the occurrence or the severity of GvHD. Our data show that the concentration of hematopoietic progenitor cells in the graft correlates with the rapidity of engraftment. However, within the range of numbers of T cells infused in this study, no correlation is present between T cells in the graft and GvHD. Therefore, nearly complete depletion of marrow grafts of T cells is probably necessary to effectively decrease the incidence of GvHD.

Eperythrozoon ovis. III. The effect of infection on blood pH, concentrations of pyruvate, lactate and glucose in blood, haematology, and on concurrent and superimposed trypanosoma vivax infection in sheep.

Infections of sheep with Eperythrozoon ovis has been shown to increase pyruvate and lactate concentrations in blood and to reduce blood pH over a period of 10-14 days post-inoculation. There was no effect on the concentration of blood glucose. However, if care is not taken to inhibit glycolysis, the concentration of blood glucose in samples of blood taken for analysis falls markedly. Rapid destruction of erythrocytes started about 10 days post-inoculation and was progressive. Superimposition of Trypanosoma vivax infection on E. ovis infection did not appear to affect the growth of either parasite.

Eperythrozoon ovis. I. Serological diagnosis of infection by the indirect immunoflurescent antibody test.

The indirect immunofluorescent antibody test (IFAT) was evaluated for the detection of Eperythrozoon ovis infection in sheep. The test first became positive, on the average, 10 days following exposure to E. ovis and remained positive for 24 months, the longest period checked. Reciprocal titres in the first three days after becoming positive in the IFAT were between 4 and 80, but rose to 640 within 9 weeks; in general titres were between 4 and 640, exceptionally titres of 1280 were obtained. Negative sera produced no fluorescence at serum dilutions of 1:4. Paired serum samples collected before and after experimental infection demonstrated the specificity of the test. Further support for the specificity and reliability of the IFAT was provided by lack of cross-reactivity between E. ovis antigen and antisera to Anaplasma ovis and Theileria ovis, the two common blood parasites of sheep and goats in Nigeria, and the results of a longitudinal survey in a flock of sheep on the research farm where E. ovis was first detected.

Eperythrozoon ovis. II. Prevalence studies in sheep in Nigeria using the indirect immunofluorescent antibody test.

A serological survey of Eperythrozoon ovis infection in sheep was carried out in the main sheep farming areas of Nigeria, using the indirect immunofluorescent antibody test. Out of a total of 402 animals surveyed, 145, representing 36 per cent, were found to be serologically positive. Approximately 90 per cent of the sero-positives were sheep kept under intensive or semi-intensive systems of management indicating that close contact facilitated spread of the parasite. Microscopic examination of representative blood smears revealed E. ovis in only 12 of the serologically positive sheep. It was concluded that endemic stability explains why the parasite has not been reported earlier in Nigeria.

Clinico-pathological study of heartwater in goats.

The clinico-pathological features of heartwater were studied in goats experimentally infected with a Nigerian isolate of Cowdria ruminantium. Significant drop in haemoglobin values and marked leukopaenia caused by lymphopaenia and neutropaenia and a fall in total serum protein were observed during the course of the disease. A significant increase in the alpha-globulins and an apparent fall in the gamma-globulins also occurred. Marked depletion of lymphocytes in the follicles of spleen and lymph nodes was observed in histological sections. A dramatic rise in blood levels of glucose, pyruvate and lactate, and a drop in blood pH occurred terminally and appeared to contribute to the fatal outcome of the disease.

Heartwater in Nigeria. II. The isolation of Cowdria ruminantium from live and dead animals and the importance of routes of inoculation.

A study was carried out to determine which materials from animals dying or dead of heartwater could initiate the disease in susceptible goats, using the intravenous and subcutaneous routes. C. ruminantium was consistently isolated by intravenous injection of the whole blood or of lung macrophages and by subcutaneous injection of brain homogenate. In animals dead of heartwater, it appeared that isolation of the organism was achieved only when extensive post-mortem autolysis had not supervened. Experiments with blood fractions showed that leucocytic and plasma fractions of infective blood transmitted heartwater; the erythrocytic fraction consistently failed to induce an infection.