The infection of young albino mice by the intraperitoneal injection of viable hydatid protoscolices provided a suitable model for the investigation of the factors controlling the subsequent host immune response. Antibodies detectable by haemagglutination and complement fixation appeared around the 14th week after infection. Increases in antibody titres were related to the potency of the antigenic impulse(s) produced by the healthy germinal membrane and viable protoscolices. Our results suggest that qualitative and quantitative variations in excretory, secretory and somatic antigens, occurring during the different phases of parasite development, incite the production of a multitude of antibodies, only a few of which are detectable by conventional methods.

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Nosocomial infections due to Acinetobacter baumannii dramatically increased in a Lebanese medical center following an outbreak of hostilities in Lebanon in 1984. The incidence of infection caused by this organism has remained high in this institution, thus requiring the implementation of a strain typing system to aid in infection control. Three methods were investigated for their utility in differentiating among a representative group of 36 nosocomial Acinetobacter baumannii isolates obtained over a 10 month period from specimens of hospitalized patients. Isolates were typed by antibiogram analyses, plasmid fingerprinting, and total cell protein profiles. Only three distinct total cell protein profiles were detected, with one pattern accounting for 26 (72.2%) of the isolates. However, eight different plasmid profiles were observed, with 20 (55.5%) isolates having the same profile. Eleven distinct antibiograms were seen with the most prevalent pattern occurring in 21 isolates. Twenty of the 21 (95%) isolates with the common antibiogram also had the same plasmid profile and total protein profile (44.4% of total isolates). The combination of these three typing methods was useful in tracing the spread of these organisms in the medical center. The data obtained suggest the distribution of a common strain among at least six wards of this hospital.

There is evidence that the yearly incidence rate of hydatid disease may be increasing in endemic areas and in regions of the world hitherto free of the infection. The availability of an accurate method of detection in both man and other animals would facilitate understanding of the global epidemiology. The diagnostic procedures in use in human hydatidosis have often given inconclusive results in animal infections. The following tests are discussed and their usefulness appraised: intradermal, complement fixation, haemagglutination, latex agglutination, indirect fluorescent antibody, immunoelectrophoresis, counter immunoelectrophoresis, enzyme linked immunosorbent assay, radio-immuno assay and lymphocyte transformation.

SUMMARYThe sensitivity of the haemagglutination, complement-fixation and indirect fluorescent antibody tests in the diagnosis of primary and recurrent hydatid disease is presented. In the first, diagnostic titres were obtained in 90%, 80 % and 96% of 50 patients with hepatic and 64%, 60% and 68% of 25 patients with pulmonary cysts, respectively. In the postoperative study of 62 patients, elevated titres of HA, CF and IFA antibodies in 30 led to the presumptive diagnosis of recurrent disease, confirmed later by radiological and surgical follow-ups. In the 32 others the proportion of positive reactors was 29%, 6% and 28% in HA, CF and IFA tests. These patients had no detectable cysts. This indicates that in postoperative patients a negative CF test may be of a better prognostic value in indicating absence of cysts than the HA and IFA tests.

The presence of cell mediated immunity to Echinococcus granulosus antigen was detected in syngeneic mice with secondary hydatidosis. Significant increases of thymidine uptake were observed in spleen cells from infected animals exposed to protoscolex or hydatid fluid antigens. A definite decrease in the number and size of cysts occurred in mice following the simultaneous intraperitoneal injection of viable protoscolices and a suspension of 1 x 10(7) sensitized spleen cells.

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Sixty-one serum samples selected on the basis of reactivity in the complement fixation (CF) and latex agglutination (LA) test, were further examined for sensitivity and specificity by indirect haemagglutination (IHA), enzyme linked immunosorbent assay (ELISA) and defined antigen substrate spheres (DASS). Twenty sera from healthy Europeans and 48 samples from patients with either schistosomiasis or trichinosis were also tested. Comparable levels of sensitivity were found between the CF and LA positive sera and IHA, ELISA and DASS. Of the CF positive LA negative group of sera, many were positive by DASS but only a few reacted in IHA and ELISA. Some cross reactivity was also observed in the schistosomiasis sera tested by IHA and ELISA.