Hepatitis A virus infection in households

The behavior of hepatitis A virus (HAV) infection among 980 members of 230 families in two rural districts of Costa Rica was studied prospectively from the recognition of the index case. The initial prevalence of detectable antibody (anti-HAV) ranged from 26.2% in children to 71.4% in adults. The ratio of index to household-associated infections was significantly higher among children than among adolescents and adults, indicating that children were most often responsible for the HAV introduction. The rates of household-associated cases among susceptible contacts were 70-83%; the final prevalences of anti-HAV were 90-95%. Neither index showed significant differences related to age. The ratio of clinical to silent infections in household-associated cases was uniformly 1.8:1 among children and adolescents; among adults, almost all associated infections were silent. Beginning with the 5-9-year age group, however, an immunoglobulin M response was absent in a progressively larger proportion of inapparent infections, strongly suggesting restimulation of specific immunoglobulin G antibodies by reinfection.

Anti-DNA, anti-HBc correlations with RIA-detected HBeAg and anti-HBe in chronic HBsAg carriers

The interrelations of 1) antibody to hepatitis B core antigen (HBcAg)--anti-HBc; 2) single-stranded DNA-binding antibodies (anti-DNA); and 3) the e-antigen/antibody system--hepatitis B e antigen (HBeAg) and antibody (anti-HBe), were studied in 150 hepatitis B surface antigen (HBsAg) carriers, in 43 of whom diagnostic liver biopsies had been performed. There was a good correlation between titers of anti-HBc and anti-DNA, regarded as indicators of viral and pathological activity, respectively, as well as between levels of these two antibodies and the presence of HBeAg or anti-HBE as detected by radio-immune assay (RIA). In general, HBeAg-positive carriers showed high anti-HBc and high anti-DNA titers, while the carriers positive for anti-HBe had low titers of both. These findings were in accord with the histopathological results. The three serologic parameters, anti-HBc, anti-DNA, and e-antigen/antibody, should together prove useful for the evaluation of the clinical status of chronic HBsAg carriers.

Quantitative image analysis: applications using sequential transformations

The theoretical foundations of quantitative image analysis and its implementation in the Leitz T.A.S. have been discussed in the preceeding paper [4]. Especially the Mathematical Morphology and its recent developments have been pointed out. Sequential image transformations are a new approach of morphological analysis. Elementary transform steps, which are hardwired in the device, performed in specific sequences, which are implemented as macroinstructions in the programming language have proven to be a very useful tool in image analysis. A specific sequence of elementary steps will be referred to as morphological function. This new approach will be illustrated by four general examples: analysis of fibers, computing the number of edges for metallic grains, separation of overlapping cells, analysis of minerals which occur free and locked to another one.

[Biomedical image analysis by mathematical morphology (author's transl)]

There coexist two types of biomedical image analysers, namely the specialized and the universal ones. This distinction corresponds to the one separating pattern recognition from structural analysis. Only specialized devices can give rise to full automation. Mathematical morphology turns out to be a common theoretical background for both kinds of analysers. It defines the logical conditions according to which quantization is possible, and provides a comprehensive class of algorithms.

Antibodies to single stranded DNA: a diagnostic aid in chronic hepatitis B virus infections

Serial determinations of titers of binding antibodies to single stranded DNA were performed over a period of three years in 43 type B hepatitis patients with persisting HBsAg who had either developed chronic hepatitis or were asymptomatic carriers. Patients with histopathological diagnosis of chronic active or chronic persistent hepatitis, with or without clinical symptoms, showed high titers of anti-DNA throughout the course of the disease, whereas in most of these patients the serum alanine transaminase and bilirubin levels fluctuated widely and were often normal; in such cases the elevation of anti-DNA was frequently the only positive sign present. On the other hand anti-DNA titers were within the normal range in chronic asymptomatic HBsAg carriers who showed no histopathological or biochemical changes. Anti-DNA determinations are proposed as a reliable diagnostic aid to supplement current procedures for assessment of the disease status during the course of chronic hepatitis B virus infections.

Endemoepidemic non-parenteral type B hepatitis in Costa Rica

In an endemic area of Costa Rica nonparenteral type B hepatitis occurs at a yearly rate of 160/100,000, in an endemoepidemic pattern with periodic localized outbreaks. In a recent episode in the village of San Rafael, 23 clinical and 67 subclinical cases, all subtype adw, originated from two carriers living in opposite ends of the village. Contact transmission was identified as the mode of spread. In a coincidental outbreak in another village, San Juan, 17 clinical and 40 subclinical cases were observed. Thirty-seven cases of HBs Ag/ayw positive hepatitis occurred in the Western sector of the village, apparently originating from contact with three HBs Ag/ayw carriers found in that area. There were also 20 cases of HBs Ag/adw positive hepatitis, but these occurred almost exclusively in the Eastern sector, where subtype adw disease has been prevalent in previous years. The geographic distribution of antibody subtypes found in the two separated sectors of the village coincided fully with that of the antigen subtypes. These observations show that personal contact is definitely a mode of transmission of hepatitis B.