The incidence of Chlamydia psittaci infections in Hamburg has been studied using the complement fixation test on 655 human sera collected from patients with respiratory tract diseases. Of the 653 sera investigated, 78 (11.9%) showed antibody titers between 1:8 and 1:128. Of the positive sera, 21 (16.9%) presented values of greater than or equal to 1:32. This infection is encountered more often in individuals over 21 years of age (15.9% to 23.4%) than in persons under 20 (0.8% to 6.0%). General practitioners' attention must be drawn to Chlamydia psittaci infections, since they seem to be of greater importance in human pathology than is generally assumed.

The occurrence of OC-43 coronarvirus-like infections in the population of Hamburg was determined by a monthly serological survey (hemagglutintion inhibition test [HI]) undertaken between October 1974 and October 1976. Studies of 3,016 sera revealed a high incidence of HI antibodies (58,2%). The frequency of seropositive reactions (= 1:8) and the geometric mean titer were higher in individuals 15 to 24 years old. Treatment of 50 postive sera (titer 1:16 -1:64) with receptor destroying enzyme, kaolin and ethacridin for elimination of nonspecific inhbitiros did not modify the HI-titer of the investigated sera. The serological seasonal pattern suggests that coronaviruses are circulating the whole year in the urban population with a prevlence in the fall-winter period. Of the 331 paired sera examined, 6.6% presented a four- to eightfold rise intiter within eight weeks.

No abstract

In the haemagglutination inhibition (HI) test, 20 cervine sera, most of which came from Northern Germany, were treated with receptor destroying enzyme (RDE) and 11 sera were found to contain antibodies against the H1N1 (A/USSR 90/77) and H3N2 (A/Victoria 13/75, A/Texas 1/77) influenza viruses. Only two sera contained antibodies against H3N2 viruses, and seven sera were negative. Evidence of the specificity of influenza antibodies was provided by the following findings: 1) the IgG serum extracts showed the same inhibitory activity of haemagglutinin as the RDE treated sera; 2) addition of protein A led to an increase in the HI titers; 3) in the haemolysis in gel test, some of the HI positive sera formed haemolysis in gel test, some of the HI positive sera formed haemolysis rings of the same diameter as hyperimmune antiinfluenza A (H1N1) serum; and 4) the cervine sera reacted positively in the neuraminidase inhibition (NI) test. It is remarkable that influenza H1N1 antibodies were found in the serum of one cervine before this virus strain appeared in humans.

Two vaccinia viruses isolated from patients with vaccinial complications (vaccinial ulcer, postvaccinial seizures) showed qualitative differences from the original parental strain. After intradermal injection of the viruses into the rabbit marked necroses developed, which the original strains did not produce. While the parental virus did not grow on the chorioallantoic membrane at 41 degrees C after 2 days incubation, the vaccinia variant produced typical lesions at that temperature. Also the yield of infectious virus on various cell systems was 1--2.5 logs higher for the virus than for the original vaccine strain. With the plaque technique differences were seen in the appearance and size of plaques between the variant and the parental vaccinia strain. These results indicate that virus of an increased pathogenicity could be isolated from the patients and this might be causally connected with the postvaccinial complications from which they were suffering.