Impacto en salud infantil del invierno 2002: disociación entre factores ambientales y virus respiratorio sincicial, en Santiago / The influence of winter 2002 in pediatric health: dissociation between environmental factors and respiratory syncytial viruses, in Santiago

BACKGROUND: The increase in winter related health pediatric demand is associated with three factors: cold and rainy weather, air pollution and respiratory viral epidemics. During the winter of 2002 there was, successively, heavy rain, air pollution, cold weather and a respiratory syncytial virus (RSV) epidemic in Santiago. AIM: To study the influence of environmental factors and RSV epidemic on pediatric health care demand. PATIENTS AND METHODS: The number of hospital admissions and outpatient consultations for acute lower respiratory infections (ALRI) from April to October 2002 (Autumn to Spring in Chile), were registered in a public pediatric hospital of Santiago. A respiratory virus surveillance (RSV, adenovirus influenza and parainfluenza virus) was carried out among children admitted for ALRI. Climate conditions and air pollution (number of particles of more than 10 microns/mm3) values were provided by local environmental health services. RESULTS: As expected, a rise in winter hospital admissions and outpatient consultations was detected, that peaked in week 29. This rise coincided with the higher RSV detection week. There was heavy rain in weeks 22, 23 and 30, as well as cold weather in June-July (weeks 23, 24, 26, 27 and 30; mid Winter), that did not increase health care demand. Likewise, high air pollution, registered from weeks 24 to 26, did not increase health care demand. CONCLUSIONS: RSV epidemic is the principal factor associated to the increase in health burden during winter in Santiago.

Bacterial and viral etiology of acute otitis media in Chilean children.

BACKGROUND: Acute otitis media (AOM) is a main cause for antimicrobial prescription in Latin America. Pathogen diversity in different geographic regions underscores the need for updated knowledge on AOM microbiology. AIM: To prospectively determine the role of bacteria and viruses in Chilean children with AOM. METHODS: Between July, 1998, and June, 1999, children >3 months with a presumptive diagnosis of AOM were referred to the study ear, nose and throat physician. Middle ear fluid and nasopharyngeal aspirates were obtained from children with confirmed AOM and processed for common bacteria, Mycoplasma pneumoniae, Chlamydia pneumoniae and viruses. Antimicrobial susceptibility patterns and serotypes of Streptococcus pneumoniae strains were determined. RESULTS: An ear, nose and throat physician confirmed diagnoses for 222 (42%) of 529 children referred with diagnosis of AOM, and 170 children met eligibility criteria for the study. One or more pathogens were detected in 140 of 170 (82%) children. Predominant bacteria were S. pneumoniae (37%), Haemophilus influenzae (24%) and Streptococcus pyogenes (13%). M. catarrhalis was detected in 2 children, C. pneumoniae was found in 1 and M. pneumoniae was not detected. Viruses were detected in 22 children (13%) from nasopharyngeal aspirates, and in 6 of them the same virus was detected in middle ear fluid. Penicillin-resistant (intermediate and high) S. pneumoniae represented 40% of isolates and 10% of H. influenzae were beta-lactamase producers. All 10 penicillin-resistant S. pneumoniae strains were resistant to cefuroxime. Eighteen S. pneumoniae serotypes were detected and 19F was associated with high level penicillin resistance. CONCLUSION: This study can impact local management of AOM, and it should encourage continuous surveillance of AOM microbiology in Chile and other developing countries.

Human caliciviruses are a significant pathogen of acute sporadic diarrhea in children of Santiago, Chile.

Human caliciviruses (HuCVs) are increasingly recognized as common pathogens that cause acute sporadic diarrhea in children; however, regional antigenic and genetic diversity complicate detection techniques. Stool samples from children seeking medical attention in 2 outpatient clinics, a large emergency department, and 2 hospital wards were evaluated for HuCVs by reverse transcription-polymerase chain reaction, using primers based on a conserved sequence of the polymerase region of a previously sequenced Chilean strain. HuCVs were detected in 53 (8%) of 684 children 1 month to 5 years of age (mean, 13 months). Detection occurred year-round without a clear seasonal peak, and detection frequency declined from 16% in 1997 to 2% in 1999. The decline may have been due to a change in virus genotype. HuCVs are a significant pathogen of acute sporadic diarrhea in Chilean children, and continuous characterization of genetic diversity will be crucial for appropriate detection.

Hospital-acquired adenovirus 7h infantile respiratory infection in Chile.

BACKGROUND: Adenoviruses are the second most common cause of viral acute lower respiratory tract infection (ALRI) requiring hospitalization in Chile. Little information is available with respect to nosocomial infection rate by adenovirus. This issue is important because of its potential severity and long term sequelae. METHODS: Infants hospitalized for ALRI were studied to determine the rate of nosocomial cross-infection with respiratory adenovirus and its corresponding genome type. The group studied included all cases younger than 2 years of age admitted to a seven crib ward in the Roberto del Rio Children's Hospital (Santiago, Chile) between May, 1995, and October, 1996. Nasopharyngeal aspirates for immunofluorescence assay and viral isolation were obtained on admission and the next day. On identification of a positive case for adenovirus, samples were obtained from contacts for 2 consecutive days and twice weekly thereafter for 2 weeks. RESULTS: Fifteen index positive cases for adenovirus and their 65 contacts were identified. Secondary attack rate for adenoviral cross-infection was 55%, most of which were diagnosed by viral isolation. Mortality occurred in 4 cases; 3 had underlying diseases. Four secondary cases presented mild respiratory infection after acquiring the cross-infection, and 16 patients developed a moderate and severe ALRI. Twelve patients required supplemental oxygen and 4 needed mechanical respiratory support. Genome types for the 10 index cases and 19 contacts were obtained. All of these corresponded to adenovirus 7h. CONCLUSIONS: The high secondary attack rate observed, stresses the importance of adequate isolation of patients and the need for rapid and sensitive viral diagnosis.

Adenovirus surveillance on children hospitalized for acute lower respiratory infections in Chile (1988-1996).

Adenoviruses (Ad) play an important role in the etiology of acute lower respiratory tract infections (ALRI) in young children in Chile. Our aim was to correlate the clinical severity of the infections with the Ad strains isolated during surveillance over 8 years. From 1988 through 1996, nasopharyngeal aspirates (NPA) were obtained for viral isolation and immunofluorescence assay (IFA) from children under 2 years of age hospitalized for ALRI; Ad isolates were further studied by restriction enzyme analysis of genomic DNA. Of 3,097 cases enrolled, the Ad isolation rate was 12.6%. The most common admission diagnoses among Ad-positive cases were pneumonia and wheezing bronchitis (69.8%). Duration of Ad shedding was studied in 74 cases by IFA. Children excreting Ad for 4 or more days had a longer hospital stay than those shedding for 1-3 days (mean: 16.8 and 7.2 days, respectively; P <.01). Viral shedding for more than 3 days was associated with more severe outcomes. Genome typing of 221 out of 390 Ad isolates resulted in 87 subgenus C and 134 subgenus B strains, including 123 Ad genome type 7h (55.6%, P <.01). The IFA from the NPA was more sensitive for the detection of subgenus B (51. 5%) than subgenus C infections (24.1%, P <.01). Children shedding Ad 7h had longer hospital stays (P <.01), a higher frequency of rectal temperatures over 39 degrees C (P <.01), and greater need for additional oxygen (P <.02) than subgenus C cases. Four cases requiring mechanical ventilation were associated with Ad 7h infections. The data presented show that, in children hospitalized for ALRI, the genome type 7h was associated with a more severe clinical outcome.

Differential effects of respiratory syncytial virus and adenovirus on mononuclear cell cytokine responses.

Respiratory syncytial virus (RSV) and adenovirus (Advs) serotype 3 (Adv3) and 7h (Adv7h) are associated with mild to severe respiratory infection and are indistinguishable during the acute phases of the illnesses. However, outcome and long-term prognosis are different with both infections. RSV infection is associated with later development of asthma, and Adv, mainly Adv7h, with severe lung damage, bronchiectasis, and hyperlucent lung. We hypothesized that this difference could be partly due to different immune responses induced by these viruses. To test this hypothesis we quantified TCD4+, TCD8+, and BCD19+ expressing the interleukin-2 receptor-alpha chain (CD25) and interferon-gamma (IFN-gamma), interleukin (IL)-10, and IL-4 in the supernatant of peripheral blood mononuclear cells (PBMC) from school children infected in vitro with and without RSV, Adv7h, and Adv3 and after phytohemagglutinin (PHA) stimulation in the presence or absence of these viruses at a multiplicity of infection (MOI) of 1. PBMC from every child produced more IL-10 (p

[Systematic surveillance of influenza, syncytial respiratory, parainfluenza and adenovirus in children with acute respiratory infections]. / Vigilancia sistemática de virus influenza, respiratorio sincicial, parainfluenza y adenovirus, en niños ambulatorios con infecciones respiratorias agudas.

BACKGROUND: The efficacy of influenza vaccination programs depends on the antigenic similitude between vaccine and the influenza virus circulating in the community. Therefore the surveillance of clinical activity and antigenic features of influenza virus is of utmost importance. AIM: To perform a systematic surveillance of clinical activity and antigenic characteristics of influenza virus. MATERIAL AND METHODS: Since 1996 and during the cold months (May to September), 20 samples of upper respiratory secretions per week, were obtained from children with acute respiratory infections consulting to the emergency room of a public hospital. Using indirect immunofluorescence and cellular cultures, the presence of influenza, syncytial respiratory, parainfluenza and adenovirus was assessed. The weekly number of consultations in the emergency room and the number of hospital discharges due to acute respiratory infections, were registered. RESULTS: Influenza and syncytial respiratory were the predominant virus detected since 1996. In 1996 and 1998, the weekly detection of influenza virus followed a single seasonal curve. The maximal weekly positively results reached 85 and 80% of the obtained samples, respectively. During 1997, two curves of influenza virus activity were observed, but none reached more than 50% of weekly positive samples. The demand for outpatient care evolved in parallel to the weekly detection of influenza virus. The hospital discharges due to acute respiratory infections paralleled the syncytial respiratory virus detection rates. CONCLUSIONS: This surveillance model is effective for the detection of influenza and other virus responsible for acute respiratory infections and their relationship with the demand for health care during the cold months.

[Influence of respiratory viruses, cold weather and air pollution in the lower respiratory tract infections in infants children]. / Influencia de virus respiratorios, frío y contaminación aérea en la infección respiratoria aguda baja del lactante.

BACKGROUND: All winters, there is an increase in the number of pediatric consultations, associated to three factors: cold weather, air pollution and respiratory virus epidemics. AIM: To study the influence of these three factors in the demand for pediatric consultations between March and September, in an area of Metropolitan Santiago. PATIENTS AND METHODS: The number of consultations between March and September 1998 in the emergency room and the number of hospital discharges due to lower respiratory tract infections, were registered in a public pediatric hospital of Santiago. A respiratory virus surveillance (respiratory syncytial virus, adenovirus, influenza and parainfluenza virus) was done among children admitted for lower respiratory infections. Atmospheric temperature values and air pollution, measured as the number of particles of 10 microns or more per m3 (MP 10), were obtained from local health services. RESULTS: Two elevation waves of outpatient consultations were detected at weeks 19 and 26, that coincided with the periods of maximal detection of influenza and syncytial respiratory virus, respectively. The epidemics of respiratory syncytial virus coincided with the maximal number of hospital admissions for lower respiratory tract infections at week 27. There was no correlation between air pollution and the number of pediatric consultations. The lower ambient temperatures coincided with the higher detection of respiratory syncytial virus at week 28, moment in which the demand for consultations or hospital admissions was descending. CONCLUSIONS: There is a direct relationship between respiratory virus epidemics and the demand for pediatric consultations. There is also a minor influence of ambient temperature.

Prevalence of astrovirus infection among Chilean children with acute gastroenteritis.

The frequency of astrovirus infection in 456 Chilean children with diarrhea was determined by enzyme-linked immunosorbent assay, reverse transcriptase PCR, and cell culture. Astrovirus was detected in 16.5% of rotavirus-negative and 7% of rotavirus-positive samples obtained from emergency rooms or hospitals and in 11% of samples from day care centers. HAst-1 was the predominant serotype identified.

Discontinuation of antimicrobial therapy for febrile, neutropenic children with cancer: a prospective study.

During a 2-year period, all children with cancer, neutropenia, and fever who were admitted to Hospital de Niños Luis Calvo Mackenna (Santiago, Chile) were enrolled in a study of the safety of stopping antibiotic therapy on day 3 of treatment. Children who met predefined criteria for nonbacterial fever were randomized on day 3 to stop (group A) or continue (group B) antibiotic therapy. A total of 220 children with cancer had 238 episodes of fever and neutropenia; 68 children with 75 episodes met entry criteria for nonbacterial fever (group A, 36; group B, 39). Both groups were comparable in terms of age, gender, oncological disease, chemotherapy status, and initial neutrophil count. Resolution of symptoms occurred in 34 of 36 episodes in group A and 36 of 39 episodes in group B (P > .05). No deaths occurred, and bacterial superinfections were uncommon. For children with cancer as well as episodes of fever and neutropenia without an identifiable bacterial etiology at admission, stopping antibiotic therapy on day 3 was safe and not associated with a higher risk of bacterial superinfections.

Respiratory syncytial virus infection in infants is associated with predominant Th-2-like response.

Viral infections have been associated with cellular immune responses and production of Th-1 cytokines. Respiratory syncytial virus (RSV), however, induces virus-specific IgE, which might be a consequence of a Th-2-like activation. To test this hypothesis we quantified interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) in the supernatant of peripheral blood mononuclear cells cultured for 24 and 48 h in the presence or absence of phytohemaglutinin and pokeweed mitogen and the lymphocyte phenotypes to analyze subsets and their activation markers, from 15 hospitalized infants during an acute lower respiratory infection caused by RSV and 17 healthy control infants from 1 to 15 mo of age. Compared with the control infants, those infected with RSV had an increase in the number of B-cells (p < 0.02) and decreases in both CD8+ T-cells (p < 0.01) and activated CD8+/CD25+ suppressor/ cytotoxic T-cells (p < 0.007). In RSV-infected infants, IFN-gamma production was subtotally suppressed, whereas IL-4 production was decreased to a lesser degree, giving significantly (p < 0.001) increased IL-4/IFN-gamma ratio compared with that in the control infants. These findings suggest a predominant Th-z-like response in RSV-infected infants, which could explain some aspects of the immunopathogenesis of RSV infection and the RSV-specific and nonspecific IgE antibody responses observed.

Molecular epidemiology of human rotaviruses in Santiago, Chile.

BACKGROUND: Protective immunity against rotavirus infection is directed against antigenic epitopes on the outer capsid proteins VP7 and VP4. Our aim was to characterize the epidemiology of rotavirus antigenic types over time in Santiago, Chile. METHODS: We prospectively obtained 2097 stool samples for rotavirus testing, VP7 (G1 to G4) and VP4 (P4, P6, P8, P9) typing from children with diarrhea evaluated in emergency rooms of 5 base hospitals of Santiago. In addition 256 rotavirus-positive samples collected between 1985 and 1987 in the north health care area of Santiago were studied. RESULTS: Of 995 rotavirus-positive samples obtained 825 (82%) were typable for 1 or more VP7 types. G1 represented 81% of the G-typed samples during 1993 through 1995 and 77% during 1985 through 1987, predominating in all health care areas. G2 was next most common in all 5 areas, representing 6 to 23% of typed samples, with 1 area, the Southeast concentrating a significantly higher number of G2 infections. G2 declined from 35% of rotavirus-positive samples in 1993 to 0% in 1995 (P < 0.001), and from 25% to 2% in the north health care area from 1985 to 1987 (P < 0.001). G4 was uncommon and significantly more prevalent in 1985 through 1987 than in 1993 through 1995 (7% vs. 3%, P = 0.015). G3 was not detected. G1P8 (53%) and G2P4 (16%) combinations were by far the most commonly detected G-P associations. CONCLUSIONS: In Santiago, Chile, rotavirus antigenic type G1P8 has been highly prevalent and G2P4 has circulated in cycles. Differences in epidemiology of rotavirus antigenic types worldwide may prove to be relevant in efficacy of rotavirus vaccines.

Treatment of respiratory syncytial virus infection with vitamin A: a randomized, placebo-controlled trial in Santiago, Chile.

BACKGROUND: Treatment with high dose vitamin A reduces complications and duration of hospitalization for children with measles. In respiratory syncytial virus (RSV) infection, as with measles, low serum vitamin A concentrations correlate with increased severity of illness. METHODS: To determine whether high dose vitamin A treatment is also effective for treating RSV disease, we conducted a randomized, double blind, placebo-controlled trial among 180 RSV-infected children between 1 month and 6 years of age at three hospitals in Santiago, Chile. Children with nasal washes positive for RSV antigen were given oral vitamin A (50,000 to 200,000 IU of retinyl palmitate, doses according to age; n = 89) or placebo (n = 91) within 2 days of admission. RESULTS: There was no significant benefit from vitamin A treatment for the overall group in duration of hospitalization, need for supplemental oxygen or time to resolve hypoxemia. For the subgroup of children with significant hypoxemia on admission (room air oxygen saturation level < or = 90%), those given vitamin A had more rapid resolution of tachypnea (P = 0.01) and a shorter duration of hospitalization (5.5 vs. 9.3 days, P = 0.09). No toxicities were seen, including excess vomiting or bulging fontanel. CONCLUSIONS: If vitamin A has a beneficial effect on the course of RSV disease, it may be seen only in more severely ill children.

Molecular epidemiology of adenovirus acute lower respiratory infections of children in the south cone of South America (1991-1994).

A collection of 165 adenovirus strains isolated from nasopharyngeal aspirates of children hospitalized for acute lower respiratory infection in Argentina, Chile, and Uruguay between 1991 and 1994 was studied by restriction enzyme analysis (work performed in the Department of Virology, University of Umeå). Of the isolates, 71% (n = 117) were identified as members of subgenus B. Of these, 101 (61.2%) corresponded to genome type 7h, four (2.4%) to genome type 3p2, four (2.4%) to genome type 11a, one (0.6%) to genome type 7b, and one (0.6%) to genome type 7c. Two isolates that were neutralized as serotype 3 and four isolates that were neutralized as serotype 7 exhibited novel BamHI cleavage profiles corresponding to three new genome types denominated 3x, 7i, and 7j. Subgenus C members represented 28.5% of all typed isolates. Five different genome types of Ad1, seven genome types of Ad2, and three genome types of Ad5 were identified of, which two, two, and one, respectively, were found to correspond to new DNA variants. Only one isolate (0.6%) corresponded to Ad4 of subgenus E. Ad7h was isolated from 17 of the 18 fatal cases recorded among the patients included in the study.

Sequence conservation and expression of the gene encoding the outer capsid glycoprotein among human group C rotaviruses of global distribution.

Group C rotaviruses have been identified recently from fecal samples of children with diarrhea in the United States. Using reverse transcriptasepolymerase chain reaction and sequence analysis, we sequenced gene 8s encoding VP7 from two U.S. strains (RI-1 and RI-2), and eight other strains isolated from patients on four continents, and compared these with the sequences of four published strains. The gene 8s of the 14 strains were remarkably conserved in size and in predicted primary and secondary structures. When the sequences of the human VP7s were compared with that of the prototype porcine Cowden strain, six regions were found variable in both deduced primary and predicted secondary structures, four of which were predicted to be hydrophilic and might determine serotype specificity. Gene 8 of the human S-1 strain was further characterized by expression in recombinant baculoviruses. The expressed product was immunogenic but failed to elicit neutralizing antibodies. Our sequence analysis indicates that all the human strains characterized to date belong to a single G genotype, which may constitute a single G serotype, pending further antigenic analysis. Whether the human strains and the Cowden strain are the same serotype remains to be determined.

[Antigenic types of circulating rotavirus in children with acute diarrhea in Santiago de Chile]. / Tipos antigénicos de rotavirus circulantes en niños con diarrea aguda en Santiago de Chile.

Protective immunity against rotavirus infection is directed against antigenic epitopes on the outer capsid proteins VP7 and VP4. The aim of this study was to characterize the VP7 and VP4 antigenic types circulating in different hospital areas of Santiago, Chile, over different time periods. Between April 1993 and April 1994 a total of 1206 stool samples were obtained from children consulting for acute no bloody diarrhea in 5 hospitals representative of the 5 major health areas of Santiago. In addition, 256 rotavirus positive samples, obtained from children with acute diarrhea consulting in the north health area of Santiago between 1985-1987 were studied. All samples were processed for rotavirus by an ELISA and all rotavirus positive samples were VP7 typed (types G1-G4) by a monoclonal antibody based ELISA. 50 rotavirus positive samples were selected for VP4 typing by PCR (types P1-P4). A total of 782 rotavirus positive samples were obtained of which 618 (79%) were typable for one specific VP7 type. VP7 type G1 represented 63% of the rotavirus positive samples and predominated in all areas evaluated throughout the entire period of observation. VP7 type G2 represented 13% of rotavirus samples, following G1 in predominance. G2 types decreased progressively in all areas in both study periods. G4 types were detected mainly during 1985-1987, and G3 types have so far not been detected. Preliminary analysis of VP4 types suggests that P1 types are predominant and closely associated with VP7 G1 type. These results are relevant for the adoption of appropriate preventive strategies for rotavirus infection, specifically aimed to the development of effective vaccines.

Genome type analysis of Chilean adenovirus strains isolated in a children's hospital between 1988 and 1990.

In a study designed to evaluate the genetic variability of adenovirus strains associated with infantile cases of respiratory disease requiring hospitalization, a collection of 136 adenovirus isolates obtained in the Roberto del Rio Children's Hospital of Santiago, Chile between June 1988 and November 1990 was studied by restriction enzyme analysis. Nasopharyngeal aspirates were obtained on admission from children under 2 years. During the study period a total of 227 adenovirus respiratory infections (ARI) were diagnosed at the ward for ARI by immunofluorescence, representing 23% of all admissions. Fifty percent of the 136 typed strains were found to belong to subgenus B, and the other 50% corresponded to subgenus C. Digestion with a set of seven enzymes allowed the identification of nine different genome types of subgenus C, three of which had not been previously described, exhibiting novel restriction patterns with either BgI II or BstEII. Ad7h, identified in 66 isolates, was the predominant genome type and was associated with the nine cases requiring mechanical respiratory assistance and with the two fatalities recorded during the 29 months. No differences were found between the age and sex distribution of subgenus B and C genomic variants, but the mean length of hospital stay (X +/- 2 SE) recorded among patients infected with subgenus B types was significantly higher (17.72 + 4.52 days (n = 55) vs. 7.54 + 1.70 days (n = 53); F = 17.22; P < 0.0001).

Genome type analysis of South American adenoviruses of subgenus C collected over a 7-year period.

A collection of 148 adenovirus strains of subgenus C collected in Argentina, Chile, and Uruguay were studied by restriction enzyme analysis of genomic DNA with endonucleases BamHI, BglII, BstEII, EcoRI, HindIII, KpnI, and SmaI. Only strains corresponding to serotypes 1, 2, and 5 were identified representing both already described and new genome types. The most frequently detected type was Ad 2 followed by Ad 1 and Ad 5. Three different genomic variants of both Ad 1 and Ad 5 were discriminated. Ad 2 with 9 genome types exhibited the greatest variability. Novel profiles emerged only in strains corresponding to this serotype by restriction with BglII and BstEII. The circulation of prototype-like strains of Ad 1 throughout the study period is note-worthy. Thirty-six of 43 strains corresponded to genome type D 1. Clearly, one genome type of each serotype predominated over the 7-year period (Ad 1 D 1, n = 36; Ad 2 D 5, n = 32, Ad 5 D 36, n = 17). Some genomic variants were detected sporadically and only in Argentina, Chile, or Uruguay whereas others were widely distributed and circulated for years. A high proportion of the analysed strains was isolated from children under one year and males were more frequently infected than females.

Nosocomial transmission of rotavirus from patients admitted with diarrhea.

We studied the transmission of rotavirus (RV) in 950 patients under 2 years of age hospitalized for diarrhea in Santiago, Chile. Stool samples were collected every other day from all patients during their entire hospital stay. To trace nosocomial transmission, we mapped the ward at the time of detection of RV. Comparative study by polyacrylamide gel electrophoresis of 315 RV isolates (180 detected upon admission of patients and 135 attributed to nosocomial transmission) allowed the identification of 18 different electropherotypes. An electropherotype similar to that of a community-acquired case was found in the same room in 81% of nosocomial cases and in the ward in 92% of nosocomial cases. It was concluded that the infants admitted shedding RV are the major source of nosocomial transmission and there was not a RV strain that was particularly transmissible.

Rotavirus detection by dot blot hybridization assay using a non-radioactive synthetic oligodeoxynucleotide probe.

A synthetic oligodeoxynucleotide of 40 nucleotides corresponding to nucleotides 33-72 of the gene coding for the viral protein VP7 of rotavirus, was used as a nucleic acid probe to develop a non-radioactive hybridization method for rotavirus detection. The probe was labelled at the 3' end with biotin-7-dATP. The sensitivity and specificity of the dot blot hybridization assay for rotavirus detection was evaluated with 303 stool specimens. The results indicate that the hybridization assay has a higher sensitivity than both PAGE and EIA. Among the rotavirus strains tested 37 different electropherotypes were found. The results suggest that rotavirus diagnosis by dot hybridization using a non-radioactive probe may become routine laboratory procedure because it is simple, highly specific and very sensitive.