Aim: To study the incidence of Rotavirus infection in children below 5 years of age.
Methods: Faecal samples from 51 children less than 5 years of age with acute gastroenteritis were collected over a period of 20 days. These samples were studied for the presence of Rotavirus antigen by Latex Agglutination(LA) and Enzyme Immunoassay(EIA). The samples were also subjected to wet mount examination with saline, iodine and stained by modified Kinyouns method to look for Cryptosporidium and cultured for diarrhoegenic pathogens.
Results: Rotavirus antigen could be detected by Latex Agglutination in 14/51(27.45%) and in 19/51(37.25%) by Enzyme Immunoassay.
Conclusion: Enzyme Immunoassay is more sensitive than Latex Agglutination for the detection of Rotavirus antigen in the faecal samples.
Key words: Rotavirus, Latex Agglutination, Enzyme Immunoassay.
Rotavirus is the most important cause of severe life threatening gastroenteritis in children accounting for 20-70% of hospitalization of children worldwide. In India, incidence of Rotavirus diarrhoea varies from 5% to 70%1. Early diagnosis is essential for effective treatment and is a pre-requisite for the control of potential outbreak2. The aim of the study was to determine the incidence of Rotavirus infection in children below 5 years of age.
Fifty-one children under five years of age suffering from diarrhea were included in the study. A single faecal sample was collected from each subject and the samples were subjected to macroscopic and microscopic examination. All the samples were devoid of mucous and blood. The samples were examined microscopically for the presence of leucocytes, RBCs, mucous, parasitic ova and cysts in saline and iodine preparations. Cryptosporidium was also looked for by the modified Kinyouns method. The faecal samples were inoculated onto alkaline peptone water and Selenite F broth and sub-cultured onto Thiosulphate Citrate Bile Salt agar and Deoxycholate Agar respectively. Direct plating onto Macconkey agar was also done. The presence of Rotavirus was detected by the Latex Agglutination (LA) method using MERITEC Rotavirus kit [Meridian diagnostics, USA]. It was compared with Enzyme Immunoassay (EIA) using the Rotaclone EIA [Meridian diagnostics, USA].
Out of the fifty-one faecal samples, Rotavirus antigen was detectable in 14 by LA (27.45%) and in 19 (37.25%) by EIA. An age- wise split up of the samples is depicted in the Table.
|Age in Months||Total Tested||LATEX||EIA|
Three of the samples showed the presence of Giardia cysts. One of the sample that showed Giardia was positive for Rotavirus antigen also. Though growth of E.coli was observed from all the samples, characterization was not attempted and therefore significance not ascertained.
Studies on Rotavirus diarrhoea have been done frequently 1,3. In a study done in Nepal3, which was the inspiration to conduct this work, Rotavirus antigen was demonstrated in 38.7% of samples by EIA (62/160). And LA though a very simple and inexpensive bedside test failed to demonstrate the antigen in 15 (35.6%) of the cases. In the present study also EIA was the more sensitive test, 5 cases being missed by LA. The majority of infections were observed in subjects between 6 months to 2 years of age. In the study done in Karnataka, India, Rotavirus was detected by LA in 19.56%, with 65% observed among 7-12 months age group. When age group and causative agents were analyzed they observed that Entero-aggregative E.coli was common between 25-36 months, Shigella between 37-60 months and Salmonella typhimurium infection between 7-12 months of age.4 In the current study also the maximum incidence of Rotavirus associated diarrhoea was observed among the 7-12 months group (97.36 %), and between 6-24 months comprised of 84.2% of all positive cases.
This clearly indicates that Rotavirus is the leading cause of diarrhoea between 6 months - 24 months of age and that rapid diagnosis will prevent unnecessary use of antibiotics and possible worsening of the condition. EIA, though more sensitive, is expensive and therefore not a very effective epidemiological tool5. To accentuate the problem is the presence of viral agents like Astrovirus, which contributes greatly to in patient morbidity6. Adenovirus 40 & 41, Norwalk virus and Caliciviruses have been documented as common causes of childhood diarrhoea. In a study at California of a group of children under 5 who had diarrhoea following hospitalization, 5.2% was due to Rotavirus.6 Therefore the management of childhood diarrhea will continue to be empirical until rapid, inexpensive diagnostic methods are available to detect the causative agent of diarrhoea.
Sri Ramachandra Medical College and Research Institute (DU).
Porur, Chennai-600 116.
Asst.Professor, Dept of Microbiology,
SRMC & RI (DU), Chennai, Porur-600 116.