Volume 9 Number 2 August 1995
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ResultsOf the 358 patients sampled, 65( 18% ) were positive for rotavirus excretion. A total of 209(58%) male and 149(42%) female cases of acute diarrhoea were examined in this study. Among the positive, Rotavirus was most frequently found (22%) in the 7-12 months age group. The frequency was less Table 2: clinical variables of rotavirus positive and negative acute diarrhoea cases at Yekatit 12 hospital.
(19%) at 0-6 months and 13-24 months (17%). Only one rotavirus positive sample was seen in the age group 25-60 months (Table 1). Statistical difference was not noticed in the distribution of rotavirus excreters in different age groups(X2 = 6.49, P = 0.09). Patients who excreted rotavirus were more (21%) among less than 13 months of age than among the age groups greater than 12 months (13%). Their difference is not statistically significant(X2 = 2.73, P = 0.09). Rotavirus excretion was higher in male cases 29/130(22%), than in females 18/94(19%) up to the age of 12 months, but the reverse is true among those > 12 months of age, male cases 9/79(11%), and female cases 9/55(16%). The ratio of the infection of male to female children was 1: 1 and, there is no statistical difference in the distribution of rotavirus by sex (X2 = 0.02, P = 0.90). A comparison of clinical variables between patients with and without rotavirus diarrhoea is shown in Table 2. High percentage of vomiting alone and fever alone were observed in both groups. The only significant differences between patients with and without rotavirus diarrhoea were the presence of vomiting and fever which were noted more frequently among rotavirus positive patients(X2 = 5.41, p = 0.02).
DiscussionIn this study, rotavirus was detected in 18 % of acute diarrhoea cases. According to other studies rotavirus is believed to be responsible for about 6% of all diarrhoea episodes and 20% of all diarrhoea deaths in children under 5 years of age(9). The percentage detection of the virus in our study was lower than that of similar hospital-based studies(5,7) done in Addis Ababa, but is higher than other tropical studies(10,11,12). Since this is a hospital- based study, all study samples comprised only cases of acute diarrhoea that were brought to the hospital for treatment. Therefore, the observed finding in this study may not reflect the true situation in the community which is not yet well studied. However, the percentage of rotavirus detection in our study is higher Table 3: Relationship between rotavirus prevalence and climatological factors
mm = millimetre oC = degree centigrade % = percent *x2 = 12.06 P = 0.007 **x2 = 10.22 P = 0.006 x2 = 5.38 P =0.068 than that of community-based longitudinal surveys(8-10%) in developing countries(9). The higher percentage detection of rotavirus among children less than two years of age is consistent with a number of similar studies carried out in Addis Abeba(5,7) and other temperate and tropical countries( 12-14) .This is in accordance with the assumption in under- developed areas that the early peak of rotavirus diarrhoea may result from early exposure to contaminated sources as well as to over- crowded homes(15). Detection of rotavirus with higher number in male cases than in females upto the age of 12 months and the revers findings for the more than 12 months of age was also noticed in our study. Whether this difference is due to sex susceptibility or by chance (to appear more in number in the hospital between the different sex and age groups) is, however, questionable and needs further investigation. The ratio of the infection of male to female children ( 1 : 1 ) was in contrast to the reported ratios of 1.5: 1 by Samir, et.al (13) from Bahrain, and 1:2.4 by Puri, et.al(16) from India. The reason(s) for these findings with different geographical location are not well understood. Vomiting followed by fever appears to be more common with rotavirus diarrhoea. Although these symptoms appear to be more common in acute rotavirus infection (7, 13,17), no clinical features could be found to distinguish rotavirus diarrhoea from that caused by other etiological agents, as described before(7,18). Rotavirus was detected throughout the study period with peak ocurrence in dry and wet seasons. The findings of this seasonal variation are different from the study carried out in Addis Ababa during 1983-1984(7) which showed a uniform distribution of the. virus throughout the year .But, similar seasonal peaks in rotavirus diarrhoea have been observed in Addis Ababa, 1977-1978(5) and some other tropical areas(19-21). Eventhough it is only a thirteen months study, factors including environmental, geographical, and viral changes may contribute to the observed seasonal pattern. The relationships observed between rotavimc; prevalence and two climatological factors have indicated agreement with the findings of temperate and tropical studies. That is, (i) total monthly rainfall for which it has been shown that, an increase in rotavirus prevalence with low rainfall(22), and (ii) monthly mean minimum and maximum temperature where an increase in rotavirus infectivity with lower temperature (14,23,24). However, rotavirus infection becomes more prevalent with increasing monthly mean relative humidity unlike in other reports (22,25,26). These observations demonstrate that climatological factors may play an important role to influence the infectivity and activity of human rotavirus in different geographical locations. In conclusion, hospital-based studies have limitations in that they do not show the real picture of diarrhoeal infections in the community .However, those limitations don't invalidate the overall findings of this study which show rotavirus as one of the major etiological agents of diarrhoea seen in infants and younger children, with seasonal pattern. To understand the reasons for the observed different findings, conducting studies covering a longer period of time is essential. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||