We conclude that infection is common in the childhood population studied with seasonal variations in prevalence and epidemic-like occurrence. Asymptomatic infection occurs, especially in teenagers, but persistent infection is rare.

A relationship between respiratory Chlamydia pneumoniae infection (RCPI) and bronchial asthma is under discussion. Our objective was to study the frequency of RCPI and whether it is associated with markers of asthma in children with recurrent or chronic bronchitis as well as pneumonia. One-hundred and forty-eight children who underwent bronchoscopy were enrolled; 42 children with additional respiratory infections were excluded. Therefore, 106 children were examined, regarding a RCPI, by polymerase chain reaction (PCR) of tracheobronchial aspirate, eosinophilic inflammation of respiratory mucosa (cytology, eosinophilic cationic protein [ECP]), total serum immunoglobulin E (IgE) and specific IgE for six important allergens, as well as lung function tests if possible. There was a RCPI in 55 of 106 children (51.9%); 25.4% of PCR positives (14/55) were weakly positive (double cut-off), which was more prevalent in the 2-5-year age-group and teenagers. Children with RCPI, inclusive of weak positives, showed a milder eosinophilia of nasal mucosa than children without RCPI (5.58% vs. 9.35%, p=0.039). Eosinophilia of > or =13% in nasal- and/or bronchial swab, as a marker for respiratory allergy, was less frequent in patients with RCPI too (7.3% vs. 21.6%, p=0.035). There were no differences in ECP. Total IgE was lower in PCR-positive children (101 vs. 179 IU/ml, p=0.032). Specific IgE with a radioallergosorbent test (RAST) of at least class 3 (as a marker for a relevant allergy), as well as any RAST above zero (to characterize early forms of allergy), were both less frequent in the RCPI group. In contrast, weak positives showed the highest rates of sensitization, surpassing RCPI negatives. In lung-function tests, vital capacity was lower in RCPI patients (87.5% vs. 95.3%, p=0.045); all parameters characterizing obstructive disturbance tended to be higher. Weak positives had both the greatest reduction of vital capacity (75.3%) and the most impaired obstructive parameters. All differences were accentuated in children of 11-18 years of age. Hence, our results indicate that in the children selected, a RCPI is common and not associated with allergic respiratory inflammation. Weak positives, however, differ, having the highest rate of allergic sensitization, reduction of lung volume, and obstructive disturbance. This group might be important in clinically observed asthma after pneumonia caused by C. pneumoniae. In these children, early diagnosis and treatment of a RCPI is recommended.

Immunocompromised patients have been shown to suffer from prolonged viral infections often without detectable immune response. Here chronic infections with low virus levels can be frequently observed. In these patients viral DNA can be detected over long periods by polymerase chain reaction (PCR). In this study parvovirus B19 presence was assessed by PCR, immunoblot and enzyme-linked immunosorbent assay in sera from children with mainly oncological and hematological diseases. In 45% of sera B19 DNA was observed. Of the children 25% had IgG antibodies to viral protein 1 and 2 (VP1/2) and 15% to nonstructural protein 1 (NS1). In 6% of children IgM antibodies to VP1/2 were detected. These results indicate that the number of children with immune response to B19 proteins is distinctly lower than the number of children with B19 DNA. Transfusions of blood products might have been a possible route for B19 infection. Establishment and maintenance of a persistent parvovirus B19 infection with or without immune response are enhanced in the analyzed immunocompromised children in comparison with immunocompetent children. A persistence of B19 DNA was demonstrated up to 10 months in patients sera.

We report the findings on a skin biopsy taken from a child acutely infected with parvovirus B19 showing the typical exanthematous rash. By indirect immunofluorescence with a monoclonal antibody to B19, viral capsid proteins were detected in epidermal cells localized mainly in the stratum basale. Additionally, B19 DNA was detected in epidermal cells of the stratum basale by in situ hybridization using a Dig-labelled B19 DNA probe. The detection of viral capsid proteins and viral DNA suggests the presence of complete viral particles. It is therefore concluded that B19 plays a direct role in the formation of the exanthematous rash in erythema infection.

An enzyme immunoassay (EIA), an immunoblot assay (IB), and an indirect immunofluorescence assay were developed for detection of human herpesvirus 7 (HHV-7) antibodies in human serum. Cross-absorption studies with EIA or IFA using HHV-7 and human herpesvirus 6 (HHV-6) antigens indicated that most human sera contain cross-reactive HHV-6 and HHV-7 antibodies and that the degree of cross-reactivity varies between individual serum specimens. Inhibition of homologous antibody activity by absorption with heterologous virus ranged from 0 to 57% by EIA. However, for every sample tested, absorption with homologous virus removed more activity than did heterologous virus. An 89-kDa protein was identified as an HHV-7-specific serologic marker by IB. Activity to this protein was not removed by absorption with HHV-6 antigen. Of the three assays, the EIA was the most sensitive (94%), while the IB was the most specific (94%). Approximately 80% of specimens collected from German adults and children older than 2 years were positive for HHV-7 antibodies by these assays.