Epidemiology Of Rotavirus Infection Research Articles

Epidemiology of rotavirus infection: the evolution of the pathogen and the success of vaccination

The review presents data on the spread of various rotavirus genotypes and its variability in the world and in Russia, which occur both due to natural causes and under the influence of vaccination against rotavirus infection, as well as on the transformation of clinical and epidemiological features of the course of this disease in children as a result of the pathogen mutations.

Epidemiology of Rotavirus Infection in Dairy Calves in Central Ethiopia

Rotavirus is a major pathogen responsible for diarrheal disease in calves and neonates resulting in loss of productivity and economic losses in dairy farms in developed and developing countries. In Ethiopia, the diarrheal disease caused by Rotavirus is not so far studied adequately. Across-sectional study was conducted from October 2019 to May 2020 to estimate the prevalence, assess associated factors, and isolate Rotavirus in calves below two months of age in the central part of Ethiopia, namely Holeta, Sululta, Bishoftu, and Sebeta. A total of 404 fecal samples, comprising 213 diarrheic and 191 non-diarrheic cases, were collected from calves of less than two months of age by simple random sampling technique. Rotavirus infection was detected using antigen detection Enzyme-linked immunosorbent assay technique. All samples positive for ELISA were propagated in Madin Darby bovine kidney cells. Data was analyzed using STATA version 13. Fisher’s exact test and logistic regression analysis were used to determine the association between prevalence of rotavirus and potential risk factors. An overall rotavirus prevalence of 1.24% (95%CI 0.40 – 2.86%) was found. The prevalence of rotavirus in diarrheic calves (1.41%) was not significantly different from the prevalence of rotavirus in non-diarrheic calves (1.04%) (p>0.05). Similarly, the origin, breed, sex, age, management, and type of farm had no significant association with the prevalence of rotavirus infection of calves (p>0.05). After 3 subsequent passages, progressive cytopathic effect i.e. Cell swelling and obscure cell boundaries, detachment and floatation of cells, cytoplasmic vacuolationas, increased cell granularity and cytoplasmic stranding were observed in all samples. The presence of rotavirus in dairy calves might entail morbidity and mortality in calves. Moreover, rotavirus infection might also lead to zoonotic transmission. Therefore, further detailed molecular epidemiological studies are warranted. Good hygienic and husbandry practices are essential to limit the spread of infection.

The Current Epidemiology of Rotavirus Infection in Children Less than 5 Years of Age after Introduction of RV Vaccine in India

Rotavirus is a major cause of severe acute gastroenteritis in infants and young children worldwide. It is responsible for 40% of childhood hospitalization. It has been estimated that about 23% of diarrhoeal death occurs due to the rotavirus infection in India. To study the epidemiology of rotavirus infection in children less than 5 years of age at a tertiary care teaching hospital. A total of 240 stool samples were collected from children <5 years of age suffering from acute diarrhea at a tertiary health care referral hospital in Western Uttar Pradesh, India. Rotavirus antigen was detected in stool by Enzyme immunoassay (EIA) which utilizes monoclonal antibodies directed against VP6 antigen. Molecular genotyping was done by nested multiplex PCR. The rotavirus antigen positivity rate was found to be 14.58% in this study. There was male preponderance and the male: female ratio was 1.5:1. Rotavirus diarrhoea was reported predominantly (42.85 %) in the age group of 13 to 24 months. The most common circulating G/P genotype strain was G9P[4] accounting for 36% of cases. Rotavirus remains a major cause of diarrhoea in children <5 years of age in Uttar Pradesh. However, the positivity rate has decreased after introduction of rotavirus vaccine into the Universal immunization program (UIP) in UP.

Observations on the epidemiology of rotavirus infection among hospitalized children younger than 5 years in 2 Ukrainian hospitals, 2007–2015

BackgroundAcute gastroenteritis remains a burden among children under 5 years of age. Ukraine joined the World Health Organization’s Global Rotavirus Surveillance Network in 2006, with a goal of providing accurate rotavirus burden data to aid policy makers in planning for rotavirus vaccine introduction. This analysis describes rotavirus epidemiology among Ukrainian children enrolled in Kyiv and Odesa, two large Ukrainian cities. MethodsChildren 0–59 months of age hospitalized for acute gastroenteritis at 2 sentinel sites in Kyiv and Odesa were enrolled into the active, prospective surveillance program. In Odesa, the surveillance period was during 2007–2015 and in Kyiv, it was during 2011–2015. Acute gastroenteritis was defined as 3 or more episodes of diarrhea per day during a 24 h period, with symptom duration before hospitalization not exceeding 7 days. Guardians of enrolled children completed a questionnaire including demographic, clinical and treatment information. Each child provided a stool specimen within 2 days of hospitalization. Stools were tested for rotavirus using ProSpecT™ Rotavirus Kit (Oxoid Ltd., Great Britain), and positive specimens were genotyped. Descriptive data are reported, as well as comparison of demographic, clinical and treatment data among rotavirus positive and negative children. ResultsDuring July 2007–June 2015, 12,350 children were enrolled in the surveillance programs and had stool specimens collected and tested for rotavirus. Overall, rotavirus infection was diagnosed in 5412/12350 (44%) of children, 929/1734 (54%) of those in Kyiv and 4483/10616 (42%) in Odesa. Rotavirus infections peaked during the winter months. Children with rotavirus acute gastroenteritis displayed more severe clinical symptoms than those without rotavirus. Predominant genotypes identified included G1P[8], G2P[4], G3 P[8], G4 P[8] and G9 P[8]. ConclusionActive surveillance of acute gastroenteritis in hospitalized children younger 5 years in two large Ukrainian cities reveals a significant burden of rotavirus infection. These data provide scientific justification for incorporating rotavirus vaccines into the Ukrainian national immunization schedule.

Impact of a publicly funded monovalent rotavirus vaccination program in the Province of Quebec (Canada)

In November 2011, the province of Quebec, Canada implemented a publicly funded rotavirus (RV) vaccination program using the monovalent RV vaccine (RV1). To assess its impact, trends in passive RV laboratory detection and Emergency Department (ED) visits for gastroenteritis (GE) at two pediatric centers were evaluated. MethodsRV tests performed were extracted from the virology laboratory databases and ED visits for GE between July 1, 2006 and June 30, 2013, from the ED databases of The Montreal Children's Hospital (MCH) and Centre Hospitalier Universitaire de Sherbrooke (CHUS). The percent positive RV tests over time and season duration were assessed using 5-week moving averages. We defined season start and end as the first two and the last two consecutive weeks where the percent positive RV tests were ≥10%, respectively. ResultsComparing the pre- and post-vaccination program periods, a decrease in the proportion of positive RV tests was seen: 15.9% vs. 5.1% (p<0.001). Pre-vaccination program, RV seasons started between December and February, peaked in March or April and ended in May. In 2011–2012, the season started in March, peaked in April, and ended in May. In 2012–2013, the season lasted 3 weeks in May. ED visits for GE decreased post-introduction of the RV1 program: from 4.8% to 3.4% in 2011–2012, and 4.2% in 2012–13 (p<0.001). In children <2 years of age, ED GE visits decreased from 7.5% to 4.8% in 2011–2012, and 5.2% in 2012–2013 (p<0.001). Admissions for GE also decreased significantly from 0.41% of all ED visits to 0.14% in 2011–2012 and 0.22% in 2012–2013 (p<0.005). ConclusionImplementation of a publicly funded RV vaccination program had a major impact on the epidemiology of RV infections in Quebec: RV seasons have started later and been of shorter duration, peak positives were fewer, and ED visits for GE decreased.

Epidemiology of Rotavirus Infection in Children Less than Five Years in Omdurman Paediatric Hospital, Khartoum, Sudan

Objective: Our objective is to study epidemiology of rotavirus infection in children less than five years during one year in Omdurman Paediatric Hospital. Materials and Methods: The study design was a setting-based study. The required data were obtained by reviewing records of a year in the hospital. Results: The findings revealed that, the total cases of rotavirus infection was 1563, majority of cases occurred among age group 1-12 months 642(41%). About 899(57.5%) of cases were males while 664(42.5%) were females. High percentage 520(33.3%) of diagnosed children came from Umbda. Most of rotavirus cases occurred during April168 (10.7%) and May 158(10.1%), Mild dehydration was found in 1121(71.7%) of cases while 320(20.5%) of patients suffered from severe dehydration. Oral rehydration therapy (ORT) were given to 1120(71.7%) of patients as treatment, intravenous fluids (IVF) to 334(21.3%) and ORT & IVF to 109 (7%). A lot of cases 1110(71%) were improved after received the treatment, 9(0.6%) were died and the rest were still suffering from the clinical features. Conclusion: The study concluded that rotavirus represents a public health problem among children less than five which and effective control measures are needed to minimize this problem.

The Molecular epidemiology of rotavirus infections in samples received from a private pathology practice during the 2010 and 2011 seasons

The molecular epidemiology of rotavirus infections in samples received from a private pathology practice during the 2010 and 2011 seasons. Rotaviruses have been identified as the most common cause of severe diarrhoea in young children. The WHO protocol on burden of disease requires research on seasonality, age of infection and genotyping of strains. Stool samples were collected from March 2010 to August 2011, and the analysis included enzyme linked immunosorbent assays, polyacrylamide gel electrophoresis, and reverse-transcription polymerase chain reaction.

MOLECULAR EPIDEMIOLOGICAL STUDIES ON ROTAVIRUS INFECTION CAUSING SEVERE DIARRHEA IN HUMAN, ANIMALS AND POULTRY

The epidemiology of rotavirus infection in human, calves, sheep, goats and poultry were studied. Among total of 800 collected fecal samples , 320 samples from human, 125 samples from calves, 82 samples from sheep, 7 samples from goats, 267 samples from poultry were collected from July 2010 to May 2011 and examined by Polyacrylamide Gel Electrophoresis and Silver Staining (PAGE-SS) technique for the detection of presence of rotavirus dsRNA. Human rotavirus was detected 10.94 % (35/320) in diarrhoeic fecal samples. The highest prevalence was recorded in September 33.33% and the lowest in May 4.54%. The prevalence of rotavirus infections was 33.33% in autumn (September), 11.69% in late autumn (October-November), 9.6% in winter (December-January), 9.72% in spring (February- March), 6.12% in summer (April-May) season in diarrhoeic samples indicated the presence of rotavirus in human round the year in Bangladesh and as such no marked seasonal variation in rotavirus infection in human. No calves, sheep and goat fecal sample was found positive for rotavirus on PAGE-SS technique. During the study period, 267 faecal samples (diarrhoeic and nondiarrhoeic) of chicken (from one day to one month of age) were tested and only one was found positive on PAGE-SS technique for rotavirus infection (0.38%; 1/267). The positive cases were found in samples collected in winter season from layer chicks aged 10 days. The migration patterns of detected positive strains were not similar on polyacrylamide gel electrophoresis and their migration speed was different types. Five electropherotypes were determined among 35 human rotavirus positive samples. All the electropherotypes were under group A and long pattern. The genome migration of avian rotavirus was distinct from human types and under group D and long pattern. In the present study, it was not investigated that bacteria, parasite or any other viruses which might be responsible for development of diarrhoea.DOI: http://dx.doi.org/10.3329/bjvm.v9i2.13473

Descriptive epidemiology of rotavirus infection in a community in North India

In India, rotavirus infections cause the death of 98621 children each year. In urban neighbourhoods in Delhi, children were followed up for 1 year to estimate the incidence of rotavirus gastroenteritis and common genotypes. Infants aged f1 week were enrolled in cohort 1 and infants aged 12 months (up to +14 days) in cohort 2. Fourteen percent (30/210) gastroenteritis episodes were positive for rotavirus. Incidence rates of rotavirus gastroenteritis episodes in the first and second year were 0.18 [95% confidence interval (CI) 0.10–0.27] and 0.14 (95% CI 0.07–0.21) episodes/child-year, respectively. The incidence rate of severe rotavirus gastroenteritis in the first year of life was 0.05 (95% CI 0.01–0.10) episodes/child-year. There were no cases in the second year. The common genotypes detected were G1P[8] (27%) and G9P[4] (23%). That severe rotavirus gastroenteritis is common in the first year of life is relevant for planning efficacy trials.

Epidemiology of rotavirus infection among young children with acute diarrhoea in Burkina Faso

BackgroundIn anticipation of vaccine introduction, we assessed epidemiology of rotavirus disease among children visiting medical centre due to acute diarrhoea in Ouagadougou, Burkina Faso.MethodsBetween November 2008 and February 2010, stool specimens from 447 children less than 5 years of age suffering from diarrhoea were tested for the presence of rotavirus by antigen detection using an immunochromatographic test. Sociodemographic, environmental and clinical factors were assessed during the study.ResultsRotavirus antigen was detected in 151 (33.8%) of the patients. Most of the cases (94.2%) were in children < 24 months of age. Fever and vomiting were the symptoms most commonly reported in association with rotavirus diarrhoea and the patients were often hospitalized. Rotavirus-associated diarrhoea occurred mostly during the season from December to April (dry season). Rotavirus infection was significantly less frequent in breast-fed than among bottle-fed babies.ConclusionsThe results of this study underscore the need to control rotavirus infections among young children in Burkina Faso and may argue a decision on the introduction of rotavirus vaccine in Burkina Faso.

Epidemiology of Rotavirus Infection in North-western Nigeria

Rotaviruses (RV) are associated with approximately 33 000 deaths in children <5 years of age annually in Nigeria. However, limited data exit on RV infection in north-western Nigeria. During July 2002 to July 2004, 1063 (869 diarrhoeic and 194 control) stool samples were collected from children <5 years of age presenting with diarrhoea in north-western Nigeria. The stools were analysed for RV antigen and further characterized by antigenic and genomic methods. RV was detected in 18% of children with diarrhoea and 7.2% of the age-matched case controls. The highest RV burden was detected in children <6-months-old. Long electropherotypes and VP6 subgroup I + II specificity predominated.

EuroRotaNet – European rotavirus strain surveillance network has been established

Az A-csoportú rotavírusok világszerte a gyermekkori súlyos gasztroenteritiszek leggyakoribb okai. A rotavírusok szero- és genotípusainak különböző földrajzi területeken észlelt megoszlása ugyanabban a szezonban és az egymást követő években egyaránt változik. Jellemző ezenkívül a genetikailag egymástól eltérő törzsek együttes előfordulása, akárcsak az adott típuson belüli variabilitás bármely területen és időben. A rotavírus elleni vakcinák széles körű alkalmazását feltételezve a közeljövőben a természetes rotavírus-fertőzések átfogó surveillance-a alapvető fontosságú lesz. Az EuroRotaNet mindenekelőtt azért jött létre, hogy átfogó információt gyűjtsön az Európában keringő rotavírusok szero- és genotípusairól. A megfogalmazott feladatok közül a legfontosabbak a következők: (i) a rotavírustörzsek hatékony tipizálási és jellemzési módszerének és algoritmusok kifejlesztése; (ii) a rotavírus-fertőzések molekuláris epidemiológiájának részletes leírása Európában; (iii) a jelenlegi genotipizálási módszerek hatékonyságának felmérése és a genetikai sodródás (drift) és váltás (shift) okozta változásokra történő reagálás; és (iv) az új törzsek európai felbukkanásának rögzítése és terjedésük nyomon követése. Mindez megfelelő alapot nyújthat a jövőbeli surveillance-tevékenységekhez, és talán lehetőséget kínál majd olyan alvizsgálatok elvégzésére, amelyekkel értékelni lehet az oltóanyagnak a leggyakoribb rotavírustörzsek által okozott fertőzések számára gyakorolt hatását az általános populációban, ki lehet szűrni azokat a genotípusokat, amelyek a vakcináció hatására létrejött ellenanyagválasz kikerülésével válnak fontossá a populációban, valamint azonosíthatók lesznek azok az új reasszoránsok, amelyek a vakcinatörzsek és a vad típusú törzsek keveredéséből jönnek létre.

Rotavirus Epidemiology in San Luis PotosÍ, Mexico

The epidemiology of rotavirus infections was investigated in San Luis Potosí, Mexico during a 6-year period. In each of the study years, the epidemic period started in October or November; peak activity was detected between December and February, and the end of the epidemic occurred in March or April. Rotavirus infections show a consistent temporal pattern in our community.

Scaling properties and symmetrical patterns in the epidemiology of rotavirus infection.

The rich epidemiological database of the incidence of rotavirus, as a cause of severe diarrhoea in young children, coupled with knowledge of the natural history of the infection, can make this virus a paradigm for studies of epidemic dynamics. The cyclic recurrence of childhood rotavirus epidemics in unvaccinated populations provides one of the best documented phenomena in population dynamics. This paper makes use of epidemiological data on rotavirus infection in young children admitted to hospital in Melbourne, Australia from 1977 to 2000. Several mathematical methods were used to characterize the overall dynamics of rotavirus infections as a whole and individually as serotypes G1, G2, G3, G4 and G9. These mathematical methods are as follows: seasonal autoregressive integrated moving-average (SARIMA) models, power spectral density (PSD), higher-order spectral analysis (HOSA) (bispectrum estimation and quadratic phase coupling (QPC)), detrended fluctuation analysis (DFA), wavelet analysis (WA) and a surrogate data analysis technique. Each of these techniques revealed different dynamic aspects of rotavirus epidemiology. In particular, we confirm the existence of an annual, biannual and a quinquennial period but additionally we found other embedded cycles (e.g. ca. 3 years). There seems to be an overall unique geometric and dynamic structure of the data despite the apparent changes in the dynamics of the last years. The inherent dynamics seems to be conserved regardless of the emergence of new serotypes, the re-emergence of old serotypes or the transient disappearance of a particular serotype. More importantly, the dynamics of all serotypes is multiple synchronized so that they behave as a single entity at the epidemic level. Overall, the whole dynamics follow a scale-free power-law fractal scaling behaviour. We found that there are three different scaling regions in the time-series, suggesting that processes influencing the epidemic dynamics of rotavirus over less than 12 months differ from those that operate between 1 and ca. 3 years, as well as those between 3 and ca. 5 years. To discard the possibility that the observed patterns could be due to artefacts, we applied a surrogate data analysis technique which enabled us to discern if only random components or linear features of the incidence of rotavirus contribute to its dynamics. The global dynamics of the epidemic is portrayed by wavelet-based incidence analysis. The resulting wavelet transform of the incidence of rotavirus crisply reveals a repeating pattern over time that looks similar on many scales (a property called self-similarity). Both the self-similar behaviour and the absence of a single characteristic scale of the power-law fractal-like scaling of the incidence of rotavirus infection imply that there is not a universal inherently more virulent serotype to which severe gastroenteritis can uniquely be ascribed.

Epidemiology of rotavirus infection in Thailand.

Rotavirus is a major cause of acute severe diarrhea in children worldwide and an important cause of death among young children in developing countries. Group A rotaviruses are antigenically complex and multiple serotypes infect humans. Reassortant rotavirus vaccines are now available which offer protection against severe illness caused by rotavirus serotypes G1-4. Before vaccines are introduced into target populations, it is necessary to establish the baseline data of the epidemiology of rotavirus infection in those countries. The purpose of the present study is to provide information related to the epidemiology of rotavirus infection in Thailand. All rotavirus studies performed in Thailand were found through Medline and Thai Index Medicus searches. A total of 26 of the most relevant studies published in international and national journals are reviewed. Most studies reported that the prevalence of rotavirus infection in Thailand was 27-34%, although a few studies have reported a prevalence above this range. The peak seasonal distribution of rotavirus infection among children hospitalized with diarrhea in Thailand was seen in the dry cool seasons: October to February. The prevalence of rotavirus infection was most frequently found in children aged 6-11 months up to 2 years. G1 was the most prevalent serotype in Thailand, followed by G2, G4 and G3, respectively. At least three G serotypes, mostly G1, G2 and G4, are seen to coexist in Thailand each epidemic year and in some studies all four G-serotypes were reported in the same epidemics. In a 1996-1997 study, G9 was the third prevailing serotype after G1 and G2, respectively. These results indicate that rotavirus epidemics occur in Thailand every year and children are the most affected population. In Thailand, although G1-G4 have been reported, G1 is the most prevalent serotype in each epidemic and G9 is becoming increasingly common.

Epidemiology of rotavirus infections in The Netherlands.

This paper reviews published and unpublished data from epidemiological and virological studies of rotavirus in the Netherlands to identify gaps in our knowledge; it includes analysis of surveillance data for seasonality and age groups at risk. Rotavirus was found in approximately 5% of stool specimens from people consulting a physician for gastroenteritis. Of these cases, 38% were under 5 y of age. A clear seasonality was observed, with a peak in rotavirus activity in winter and early spring. In one hospital-based study between 1976 and 1983, rotavirus was found in 30% of children under 3 y of age hospitalized for gastroenteritis. In addition, nosocomial infections have been documented. Analysis of monthly data from laboratory surveillance from 1981 to 1996 showed that between 6 and 16% of stool samples tested positive for rotavirus, again with a clear seasonal distribution. A total of 98% of rotavirus strains that were typed were G-type 1-4. We conclude that more recent data about hospitalization rates are needed for a well-founded cost-benefit analysis.

Impact of rotavirus disease in Spain: an estimate of hospital admissions due to rotavirus.

The epidemiology of rotavirus infection in Spain was investigated using information from existing surveillance systems. Reports from laboratories and data on hospital admissions were used to estimate the number of hospital admissions due to rotavirus infection. Between January 1989 and December 1995 there were 8265 reports of rotavirus identification in the Sistema de Información Microbiológica, a voluntary national laboratory surveillance system. Where age was reported, 89.2% were in children under 5 y old. This represents 21.8% of all pathogens identified in faecal specimens in children of this age group. Between January and December 1994 there were 5639 admissions coded as "infectious intestinal disease" and 8225 as "non-infective gastroenteritis" in children under 5 y of age in the Conjunto Mínimo Básico de Datos, an obligatory hospital admissions surveillance system which covers 83% of public hospitals. Using regression analysis of admission data and laboratory reports it was estimated that rotavirus infection accounted for 3519 (25.3%) of the hospital admissions. We estimate that 4239 admissions attributable to rotavirus occurred in children under 5 y of age in Spain in 1994, a rate of 2.5/1000 population in this age group. These estimates are lower than those published for other countries, where the burden of disease is considered high enough to warrant a national vaccination programme. A cost-effectiveness study with Spanish information is essential before embarking on a national vaccination programme.

Epidemiology of rotavirus infection in five different locations in the Asian area

Between 1991 and 1994, serotypes and electropherotypes were determined for clinical specimens of group A human rotavirus (HRV) rotavirus collected from five different locations in the Asia, Saitama, Shizuoka, Taichung, Hong Kong, and Beijing. HRVs were detected through the year in Taichung and Hong Kong. The peaks of each rotavirus season were in January in Hong Kong, in March in Taichung, and in February and March in Saitama and Shizouka. We set one study year as that from July to next June. Serotype G1 was the most prevalent strain in the five different settings. Most of serotype G3 strains were identified in the study year 1991. Serotype G2 was the most predominant in Shizuoka and Taichung in the year 1993. Electropherotypes indicated the possible G types except in six cases of an unusual variant type whereas the serotype was G2 and the electropherotype was the "long" type. Five of the 502 cases and three of the 622 cases were identified as group C HRV by PAGE in Saitama and Shizouka respectively. In 216 samples in Taichung, no group C HRV strain was detected.

東京およびその周辺地域のヒトロタウイルスの流行疫学について

Epidemiology of rotavirus infection was studied from 1981 to 1988 mainly in three hospitals around Tokyo area. Major serotypes of rotaviruses in the three places were different from those in two hospitals around Kansai area in Japan (Ref. 6, 13), while, major serotypes were same among three hospitals. Both of serotypes 1 and 4 in group A were mostly found around Tokyo area. Frequencies of type 2, 3, and 9 in group A were low, although the frequencies were various among periods. Detail examinations of rotavirus RNA electropherotypes showed the results as follows; different electropherotypes were found during one winter season and at one hospital, the identical electropherotype was found cross a year and cross a hospital. We could not find the identical electropherotype which belong to two serotypes so far. Seven group C rotaviruses were found since 1987 in three hospitals. It would be important to examine RNA electropherotypes and serotypes for long period not only for epidemiological studies but also for development of vaccine.

Rotavirus gastroenteritis in southern California.

The epidemiology of rotavirus infections in Southern California was analyzed over a three year period, from January 1, 1981 through December 31, 1983. Data was available from patients seen at the University of California Irvine Medical Center (UCIMC), in addition to referral testing provided to the community in Orange County. Over the 3 yr period the laboratory performed 1172 rotavirus assays. Out of these, 345 were positive for an overall positive rate of 29.4%. The 643 stool specimens from UCIMC corresponded to 508 patients, of which 31.1% (158/508) were positive for rotavirus. The majority of patients with a positive rotavirus test were under 1 yr of age (117/158), with only ten cases found in the 2-15 yr old group. The distribution of the positive rotavirus tests was similar for the female and male population. Approximately 70% of the positive results occur during October through December, with the month of November having the highest incidence. The distribution of positive rotavirus tests did not appear to correlate with either the coldest or the driest month of the year in Southern California.