Secondary dengue virus infections during the 2009 outbreak in Buenos Aires.

OBJECTIVES: To evaluate the occurrence of secondary dengue virus (DENV) infections during the 2009 outbreak in a non-endemic area. Viral loads were evaluated in serum from acute-phase patients, comparing primary and secondary infection. METHODS: Serum samples from patients with clinical diagnosis of suspected dengue were referred to the Virology Laboratory at 'Ricardo Gutiérrez' Children's Hospital. Dengue-positive samples were classified as primary or secondary DENV infections through serological methods (anti-DENV IgM and IgG). Viral loads were measured by quantitative real-time PCR (qRT-PCR) in samples obtained in the first 5 days of infection. Statistical analyses were performed to evaluate factors that might correlate with differences in the viral load of primary or secondary infection. RESULTS: A total of 229 DENV cases were confirmed; among them, 22.7% were secondary infections. No significant differences were found between the viral load of primary and secondary infections. CONCLUSION: We detected a high percentage of secondary DENV infections in a non-endemic area; this finding might correspond to socio-demographic characteristics of the group under study or indicate a previous cryptic DENV circulation causing inapparent infections.

Molecular typing of adenoviruses in pediatric respiratory infections in Buenos Aires, Argentina (1999-2010).

BACKGROUND: The human adenovirus (HAdV) types most commonly found in respiratory samples belong to HAdV species C (HAdV-C1, -C2, -C5, and -C6) and to HAdV species B (HAdV-B3 and -B7). Several studies in South America have shown the association between severe respiratory infections and subspecies B1. OBJECTIVES: The aim of this study was to identify the adenovirus types associated with acute lower respiratory tract infections in children, found as single or coinfections, throughout a 12-year period. STUDY DESIGN: All samples that tested positive for adenovirus by immunofluorescence assay from January 1999 to December 2010 were typed by evaluating a set of four viral genes (E1A, VA, hexon and fiber). Quantitative PCRs for HAdV-B and HAdV-C species were performed to compare the viral load found in single infections and coinfections. RESULTS: From a total of 743 HAdV, 654 (88%) were single infections and 89 (12%) coinfections. From the 654 single HAdV infections, members of four species were present: species B (n=492, 75.23%), species C (n=138, 21.1%), species E (n=19, 2.91%), and species D (n=5, 0.76%). Only members of species B (n=109, 57.67%) and species C (n=80, 42.33%) were detected in coinfections. HAdV-B7 and HAdV-B3 were the most prevalent types (n=308, 36.54%; n=230, 27.28% respectively) and HAdV-C1, -C2, -E4, -C5, -C6, -D8, -B11, -B14 and -B21 were also detected. Viral loads for species C viruses were higher in single infections than in coinfections (p<0.01), whereas the opposite was observed for species B viruses (p<0.0001). CONCLUSIONS: This study provides a thorough description of adenovirus circulation and diversity in Buenos Aires in a 12-year period. The high proportion of coinfections found in this work shows that this phenomenom might be more common than expected.

Finger tendon involvement in rheumatoid arthritis. Evaluation with high-frequency sonography.

OBJECTIVE: To characterize finger tendon involvement in patients with rheumatoid arthritis (RA). METHODS: The finger tendons of 20 RA patients were studied by ultrasonography using a high-frequency (13-MHz) transducer. RESULTS: Eighteen patients (90%) showed finger tendon abnormalities: widening of the flexor tendon sheath (80%), loss of the normal fibrillar echotexture (60%), irregularity of the extensor (30%) and flexor (50%) tendon margins, tendon tear (10%), synovial cyst (20%). CONCLUSION: High-frequency sonography is helpful in assessing even minimal finger tendon lesions in RA patients.

Ultrasound examination of metacarpophalangeal joints in rheumatoid arthritis.

To evaluate the ability of ultrasonography with high frequency transducer (13-MHz) in detecting metacarpophalangeal (MCP) joint abnormalities, 20 patients with rheumatoid arthritis (RA) and a symptomatic involvement of MCP joints were studied. Twenty healthy subjects served as controls. In all RA patients, ultrasonography clearly demonstrated one or more soft tissue and/or bone abnormalities. Sixteen patients (80%) had joint cavity widening because of effusion (1 case), synovial thickening (7 cases), and joint effusion with synovial thickening (8 cases). Loss of definition of the metacarpal articular cartilage was observed in 17 cases (85%). Sixteen (80%) had bone erosions and 9 (45%) showed a definite widening of the flexor tendons sheath. Margin irregularities of the extensor and flexor tendons were respectively visualized in 7 (35%) and in 8 (40%) cases. An extensor tendon rupture was observed in 2 cases (10%). Ultrasound examination by 13-MHz transducer appears to increase the accuracy of MCP joints evaluation in RA with respect to conventional radiography. It can be recommended as the first investigation in the assessment of soft tissue involvement in RA patients.