Leonardo J. Ferreyra

The epidemiology of acute viral gastroenteritis in hospitalized children in Cordoba city, Argentina: an insight of disease burden

Information concerning the disease burden of viral gastroenteritis has important implications for the use and monitoring the impact of public health policies. The present study, carried out in Córdoba city, Argentina, documents the epidemiology of severe viral diarrhea as well as the burden of viral gastrointestinal disease in the hospital children admission. A total of 133 stools were collected from hospitalized children (Town Childhood Hospital) suffering from acute diarrhea and studied for the presence of Group A rotavirus, astrovirus and adenovirus 40/41 by enzyme-immuno assay, between November 1997 and October 1998. Enteric viruses accounted for 42.1% of the total diarrheal cases analyzed. Group A rotaviruses, astroviruses, adenoviruses 40/41 and mixed infections were found in 35.3, 4.5, 1.5, and 0.8% studied specimens respectively. We estimated that 1 in 27 children in the 0-35 month-old cohort/range would be annually hospitalized for a viral gastroenteritis illness. The major impact on viral diarrhea lies on rotaviral infection, accounting for 84.0% of the viral diarrheal cases analyzed and for approximately one third of severe diarrheas requiring hospital admission in Córdoba City, Argentina.

Genetic Analysis of a Novel Human Adenovirus With a Serologically Unique Hexon and a Recombinant Fiber Gene

In February of 1996 a human adenovirus (formerly known as Ad-Cor-96-487) was isolated from the stool of an AIDS patient who presented with severe chronic diarrhea. To characterize this apparently novel pathogen of potential public health significance, the complete genome of this adenovirus was sequenced to elucidate its origin. Bioinformatic and phylogenetic analyses of this genome demonstrate that this virus, heretofore referred to as HAdV-D58, contains a novel hexon gene as well as a recombinant fiber gene. In addition, serological analysis demonstrated that HAdV-D58 has a different neutralization profile than all previously characterized HAdVs. Bootscan analysis of the HAdV-D58 fiber gene strongly suggests one recombination event.

Picobirnavirus (PBV) natural hosts in captivity and virus excretion pattern in infected animals

Summary.A picobirnavirus (PBV) analysis was carried out by polyacrylamide gel electrophoresis of 513 stool samples obtained from 150 animal species collected from the Córdoba city zoo. The purpose of the present study was to determine susceptible species for PBV infection, the viral excretion pattern in infected animals, and the potential association with PBV diarrheic illness.Our findings suggest that PBVs are widespread in animals and could have a similar excretion behavior to that previously detected in infected humans. No disease association with PBV infection could be demonstrated. Thus, infected animals could be persistently infected asymptomatic carriers and could serve as reservoirs of infection.

Correlation between rotavirus A genotypes detected in hospitalized children and sewage samples in 2006, Córdoba, Argentina

Routine rotavirus A (RV‐A) surveillance is based on clinical cases, so only symptomatic infections are reported. The objective of this study was to determine whether the RV‐A genotypes and cold seasonal pattern described in patients with diarrhea is reflected by sewage surveillance, which could be representative of the RV‐A genotypes circulating in the population. The genotype distribution of RV‐A in effluent samples from a local sewage treatment plant was compared to those from local clinical cases. A total of 52 sewage samples and 70 stool specimens from children with acute non‐bacterial diarrhea were collected from January to December 2006. The effluent specimens were concentrated and RNA extracts from concentrated sewage and clinical samples were genotyped for the rotavirus VP7 gene. The proportional distribution of the RV‐A G‐genotypes in sewage and clinical samples during the cold season was similar: G1 accounted for 26.6% of the typed sewage isolates and 28.8% of the clinical infections; G3 type accounted for 21.9% and 25.8%; G2 type 15.6% and 10.6%; G4 type 17.2% and 21.2%; G8 type 1.6% and 0%; and the G9 type 17.2% and 13.6%, respectively. A similar picture of RV‐A genotype detection was obtained in sewage samples collected during the cold and warm seasons. The results indicate that there is a correlation between genotypes of RV‐A isolates from human diarrheic patients and of those from sewage samples. In addition, sewage monitoring highlighted the uniform all‐year RV‐A circulation, which was in contrast to the peak incidence of RV‐A infection in the community. J. Med. Virol. 82: 1277–1281, 2010.

Picobirnavirus causes persistent infection in pigs.

A study aimed to further understand the biology of porcine picobirnaviruses (PBV) was conducted between November 2003 and January 2008, on a farm located in the outskirts of Córdoba City, Argentina. PBV prevalence was examined by polyacrylamide gel electrophoresis and silver staining (PAGE S/S) on a total of 265 samples collected from pigs divided into four groups, according to age and physiological status. PBV detection rate was highest in the group of sows sampled within the lactogenic period (38.02%; p<0.05), followed by pregnant sows (15.09%), piglets aged 2-5 months of age (18.42%) and adult (> or =50 weeks) male pigs (0%). In addition, 103 samples collected in 3 follow-up studies were analyzed by PAGE S/S and reverse transcription followed by PCR (RT-PCR). Two of these studies followed female pigs from weaning up to slaughter and a third one from weaning up to 4 pregnancy periods. The results provide evidence that PBV establishes a persistent infection in the host with periods of silence intermingled with periods of low and high viral excretion. High PBV excretion levels were detected by PAGE S/S and were conditioned by age (primary infection) and host physiological status. Low PBV excretion levels were detected by RT-PCR throughout the entire study period. Sequence analysis of selected amplicons indicated that the virus excreted through the follow-up study was the same. These results suggest that porcine PBV is maintained in nature by transmission from infected asymptomatic individuals to susceptible ones.

Rotavirus seasonality in urban sewage from Argentina: effect of meteorological variables on the viral load and the genetic diversity.

In Argentina, the rotavirus disease exhibits seasonal variations, being most prevalent in the fall and winter months. To deepen the understanding of rotavirus seasonality in our community, the influence of meteorological factors on the rotavirus load and the genetic diversity in urban raw sewage from Córdoba city, Argentina were evaluated. Wastewater samples were collected monthly during a three-year study period and viral particles were concentrated by polyethylene glycol precipitation. RT-nested PCR was applied for rotavirus detection, and VP7/VP4 characterization and real-time PCR for rotavirus quantification. Both molecular techniques showed relatively similar sensitivity rates and revealed rotavirus presence in urban wastewater in cold and warm seasons, indicating its circulation in the local community all year round. However, a slight trend for rotavirus circulation was noted by real-time PCR in the fall and winter seasons, showing a significantly higher peak of rotavirus concentration at mean temperatures lower than 18°C and also higher, although not statistically different during drier weather. VP7 and VP4 gene characterization showed that G1 and P[8] genotypes were dominant, and temporal variations in genotype distribution were not observed. Rotavirus spread is complex and our results point out that weather factors alone cannot explain the seasonal quantitative pattern of the rotavirus disease. Therefore, alternative transmission routes, changes in human behavior and susceptibility, and the stability and survivability of the virus might all together contribute to the seasonality of rotavirus. The results obtained here provide evidence regarding the dynamics of rotavirus circulation and maintenance in Argentina.

A novel human adenovirus hexon protein of species D found in an AIDS patient

To date, human adenoviruses are classified into 53 types (types 1–51 and types 53 and 54), which have been grouped into six species named A through F, and the recently identified type 52 has been proposed as member of a new species, G. Type classification is based on type-specific epitopes within loop 1 (L1) and loop 2 (L2) of the hexon protein, which contain seven hypervariable regions that are responsible for type specificity. In this paper, we present the characterization of an adenovirus strain isolated from a male AIDS patient in Cordoba, Argentina. This strain was found to be a member of species D by genomic Sma I restriction analysis. Sequencing of the L1 and L2 regions of the hexon gene and immunological characterization by virus neutralization revealed this hexon to be unique and distinct from the previously identified hexons of types within species D. A seroepidemiologic study in the human population of Cordoba showed that this strain was not endemic in the local human population.

Twenty year study of the occurrence of reovirus infection in hospitalized children with acute gastroenteritis in Argentina

We studied the occurrence of reovirus infection in children hospitalized with acute gastroenteritis in Argentina during a 20-year interval (1981 through 2001). Three of 2854 (0.10%) stools were positive for reovirus but negative for adenovirus, astrovirus and rotavirus. Children infected with reovirus were <1 year old; one had meningoencephalitis in addition to gastroenteritis. This study indicates that reovirus is an uncommon cause of childhood gastroenteritis requires medical assistance.

IgG subclasses and DNA detection of HHV‐6 and HHV‐7 in healthy individuals

Human herpesvirus 6 (HHV‐6) and 7 (HHV‐7) are common opportunistic agents in immunocompromised hosts, although infection with HHV‐6 and HHV‐7 can also be observed in immunocompetent hosts. Despite similar biology and epidemiology, this study evaluated differences in the IgG subclass distribution associated with HHV‐6 and HHV‐7 in seropositive, healthy persons. The identified subclasses were also compared with the detection of HHV‐6 and HHV‐7 DNA. For these assays, sera, plasma, and saliva samples were obtained from 40 healthy blood donors in Argentina who were seropositive for both HHV‐6 and HHV‐7. HHV‐6 and HHV‐7 DNA were detected in saliva and plasma samples using nested PCR, and specific IgG subclasses were determined using immunofluorescent assays of sera samples. HHV‐7 DNA was detected in 90% of all plasma samples and in 100% of saliva samples. In contrast, HHV‐6 DNA was not detected in any of the plasma samples, and it was detected in only 6 of 40 saliva samples. Determination of IgG subclass distributions showed that HHV‐6 was restricted to IgG1, whereas HHV‐7 IgG subclasses included two groups, one restricted only to IgG1 and the other to IgG1 and IgG3. These results demonstrate the differences between HHV‐6 and HHV‐7 DNA range detection in saliva and plasma samples, as well as the IgG subclass patterns for each virus type, in healthy persons in Argentina. J. Med. Virol. 82:1679–1683, 2010. 2010 Wiley‐Liss, Inc.

Tracking novel adenovirus in environmental and human clinical samples: no evidence of endemic human adenovirus type 58 circulation in Córdoba city, Argentina

In recent years, several types of human adenovirus (HAdV) have arisen from the recombination between two or more previously known HAdV types, but their epidemiology is poorly understood. In this study, we investigated the circulation of HAdV-58, a recently described HAdV isolated from an HIV-positive patient in Córdoba city, Argentina. For this purpose, a 30-month survey was conducted to study the presence of this type of adenovirus in sewage samples collected at the inlet from a wastewater treatment plant in Córdoba city, Argentina. Complementarily, the virus was sought in stools of HIV-positive patients. Although HAdVs were detected in human stool samples and in a high percentage of sewage samples, no evidence of HAdV-58 circulation was detected. We suggest that there is no endemic circulation of HAdV-58 in the geographical local area. The trend is that the number of identified HAdVs increases over time. In this context, understanding the current circulating HAdVs may be biologically relevant.