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.

Detection of interleukin 10 in cerebrospinal fluid of patients with subacute sclerosing panencephalitis

Subacute sclerosing panencephalitis (SSPE) is a neurodegenerative disorder due to persistent measles virus infection, with high level of measles-specific antibodies in cerebrospinal fluid (CSF). To analyze whether such response arises from a TH2-biased response, the authors determined TH1 (interferon [IFN]-gamma) and TH2 (interleukin [IL]-4 and IL-10) cytokines in CSF, taken at diagnosis, of eight SSPE patients (median age, 57.5 month, range 42 to 76 months). All patients presented IL-10 (median 29.3 pg/ml, range 4.3 to 162 pg/ml), but not IL-4 (<10 pg/ml); only one case showed IFN-gamma (162 pg/ml). These results are consistent with a TH2 bias or with a local, anti-inflammatory or neuroprotective mechanism involving IL-10.

Measles virus circulation in Argentina: 1991-1999

Nucleoprotein (N) and Haemagglutinin (H) genes from measles viruses isolated from Argentina before and after the 1993 and 1998 massive vaccination campaigns were characterised to determine genetic variations that occurred from 1991 to 1999. Measles viruses from the 1991-94 period were clustered with the C1 genotype and those from 1997-99 with D6. Genetic variations within the 1997-99 outbreak were less than 1.2% and 0.79% for the N and H sequences respectively. The C1 genotype has not been detected since 1994 and the finding that a single D6 virus was found in November 1999 demonstrates that wild type viruses are still circulating among a partially covered population.

Measles resurgence in Argentina: 1997-8 outbreak

Epidemiological and clinical findings from 1162 serologically confirmed measles cases occurring in Buenos Aires, Argentina in 1997 and 1998 were retrospectively reviewed. From 90 hospitalized children, measles virus was detected by direct RT-PCR from nasopharyngeal secretions. Patients were grouped as follows: (i) not vaccinated: infants < 12 months; (ii) regularly vaccinated: children 1-4 years not covered by the last catch-up; (iii) catch-up vaccinated: patients 5-19 years immunized during the 1993 campaign. Most cases were recorded in non-vaccinated infants (54%), and the lowest in catch-up vaccinated children (16%). Mean age of the 90 hospitalized children was 11.3 months. Pneumonia was the major hospitalization cause followed by pneumonitis. Two children required intensive care and one died. The 1993 catch-up campaign seemed to reduce the number of cases in the 5- to 19-year-old group. Lack of timely follow-up probably led to the accumulation of susceptible individuals allowing measles re-emergence. Direct viral detection by RT-PCR proved to be a sensitive tool for molecular epidemiology surveillance.

Sequence analysis of measles virus hemagglutinin isolated in Argentina during the 1997-1998 outbreak

Sequence analysis was performed on 50 measles viruses (MV) isolated in Argentina. Forty-six were obtained during the current outbreak (1997-1998), three from the previous outbreak (1991) and one sporadic case (1994). A 377-bp fragment of the hemagglutinin (H) gene was directly amplified by RT-PCR from nasopharyngeal secretions. Nucleotides 8152 to 8417 were sequenced and subjected to phylogenetic analysis. Multiple silent changes and point mutations were found in all MVs. In 1991, substitutions affected the third base in codons resulting in silent changes. In 1994 an A-->C substitution at position 8321 changed amino acids 351 (Leu-->Ile). In 1997-1998, an A-->G substitution at position 8339 changed amino acids 357 (Val-->Ile). In 3/46 viruses, guanine deletion at position 8205 changed the reading frame and insertion of an extra cytosine at nucleotide 8235 shifted it back to the original frame. Phylogenetic analysis revealed that viruses leading to the last two major outbreaks are clustered into two separate branches. MVs that prevailed until 1994 were related to genotype C1 and MVs of the current outbreak to D6. Random drift mutations rendered a 0.5 ratio of nonsilent over silent mutations in most of the MVs analyzed. However, in those showing a reading frame shift, the ratio was greater than 1, suggesting that it was driven by immune selection.

[Endocervical and endometrial atypical intestinal metaplasia, concomitant with leiomyosarcoma]

One case of Intestinal Metaplasia with moderate Dysplasia of the cervix and endometrium associated to leiomyosarcoma is presented. Clinical and Anatomo-Pathological aspects are reviewed.