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Indian Journal of Community Medicine

A Longitudinal Study on ARI among Rural Under Fives

Author(s): Nilanjan Kumar Mitra

Vol. 26, No. 1 (2001-01 - 2001-03)

Deptt. of Community Medicine, North Bengal Medical College, Sushrutnagar, Dist. Darjeeling, West Bengal


Research questions: 1. What is Acute Respiratory Infection (ARI) morbidity among underfive children in rural areas? 2. What are the epidemiological factors associated with such ARI morbidity?

Objectives: 1. To determine the ARI morbidity among children of less than 5 years of age. 2. To evaluate the role of some epidemiological factors with respect to ARI morbidity.

Study design: Longitudinal study.

Setting: Durgarampur village; Singur Block; District Hooghly.

Participants: Children aged less than 5 years.

Study variables: Socio-economic class, literacy status of mother, age, sex, birth weight, birth order, nutritional and immunization status of the children, Vitamin A prophylaxis coverage, infant feeding practices, overcrowding and indoor smoke pollution.

Outcome variables: Episodes of Acute Respiratory Infections.

Statistical analysis: Incidence density and risk ratio analysis.

Methods: 63 children were followed up with periodic home visits at two weeks interval for 6 months. Frequency of ARI episodes were studied and association with study variables were analyzed.

Results: Overall incidence density rate of ARI episodes was 19.57 (C.I.- 15.60-24.57) /100 person-months at risk. Incidence was highest in infants (23.9/100 person-months). Risk ratio analysis showed that low socio-economic class, low birth weight, under-nutrition of the child, inadequate immunization, children not exclusively breastfed and indoor smoke pollution were significantly associated with increasing number of ARI episodes.

Conclusion: The study strongly points towards the importance of basic health promotional measures like proper infant feeding practices, proper nutrition of the child, improved general conditions of living in prevention and control of ARI.

Keywords: Longitudinal study, ARI, Under-five children


Acute Respiratory Infection (ARI) is an acute infection of any part of the respiratory tract and related structures including paranasal sinuses, middle ear and pleural cavity. It includes all infections of less than 30 days duration except those of the middle ear where the duration of acute episode is less than 14 days1. ARI constitutes a leading cause of morbidity and mortality especially in children. Of the 15 million child deaths in the world annually, ARI alone accounts for 4 million2. ARI accounted for 30-60% of pediatric outpatient attendance and 20-30% hospital admissions3. ARI also leads to significant disability in the form of chronic illnesses like deafness, breathing difficulty etc. in the children.

Inspite of increasing public health importance, management and control of ARI remains a neglected entity in most of the National MCH activities including recently introduced RCH programme. One of the main reasons apart from operational constraint is lack of community based epidemiological surveillance related to the magnitude and risk factors on ARI. So, generating a thorough database in rural population through longitudinal studies and its appropriate analysis emerges as a necessity.

This longitudinal study was formulated with the objective to determine the ARI morbidity among rural underfives and to study some of the epidemiological factors responsible for such morbidity.

Material and Methods:

All (63) children less than 5 years of age, living in the village of Durgarampur (population - 548) in Singur Block of District Hooghly were included in the study. The entire study area was divided into four sectors and the families were numbered. Each family contained the sector code followed by a numerical code. The children of the study area were *also numbered after the sector and family code. The new births occurring during the study period were not considered, so also the shifted age of children included in the study were not considered for the purpose of clarity and convenience. During the first visit, baseline data was collected through interviews in the local language on a pre-tested proforma. The study group was followed up at home at two weeks interval, for a period of six months (from January to June, 1997) in order to examine the children for ARI and collect history of an ARI episode (from the mother) during the preceding days.

History of nasal discharge (watery/mucous), cough, fever, sore throat, breathing difficulty, any discharge from ear etc. - alone or in combination was used in recognition of an episode of ARI and confirmed subsequently by physical examination of the child, wherever possible. An absence of symptoms for three days or more is the criterion used to differentiate one episode from another4. The tools used in this study were a pre-designed and pre-tested schedule, weighing machine, stethoscope and a digital watch.

Nutritional status was assessed as per IAP classification and Modified Prasad's Scale5 was followed for determination for socio-economic status.

As the statistical analysis of this study was based on episode incidence6, measures of disease occurrence as well as measures of association were expressed in more appropriate terms of incidence density and risk ratio (incidence density among exposed/incidence density among non-exposed) respectively.


Table I: Age-sex distribution of ARI episodes.

Age Males Females Total
(in years) No. Episodes ID/100PM* No. Episodes ID/100PM* Episodes ID/100 PM*
0-1 9 13 24.0 7 10 23.8 23 23.9
1-2 7 7 16.6 4 8 33.3 15 22.7
2-3 5 8 26.6 5 8 26.6 16 26.6
3-4 4 2 8.33 6 5 13.8 7 11.6
4-5 11 4 6.06 5 9 30.0 13 13.5
Total 36 34 15.7 27 40 24.6 74 19.6

*ID/100 PM - Incidence density/100 person-months.

36 males and 27 females made up the study group. All 63 children were followed up regularly for six months. During the total period of observation 74 episodes of ARI were encountered which amounted to 1.17 episodes of ARI per child during this period. Overall incidence density of ARI episodes was found to be 19.57/100 person months. Using Poisson distribution6, 95% confidence interval around incidence density rate was 15.60-24-57/100 person months at risk. Incidence density of ARI episodes for males and females were 15.74 and 24.6 respectively. But sex difference was not significant at 95% confidence limits. Highest number of ARI episodes (incidence density 23.9/100 person months) was recorded among infants (Table I).

Table II: Risk ratio for some selected risk factors of ARI.

Study variables No. of children No. of episodes (n=74) Risk ratio (R.r.) 95% C.I. of R.r. P value
Socio-economic class (per capita monthly income) (n=63)
>Rs.1000/- 39 62 3.19 1.71-5.91 <0.05
> Rs.1000/- 24 12
Smoke nuisance(n=63)
Present 50 66 2.15 1.03-4.46 <0.05
Absent 13 8
Birht weight (n=63)
<2.5 Kgs. 19 48 4.25 2.62-6.82 <0.05
>2.5 Kg. 44 26
Nutritional status (n=63)
Normally nourished 25 18 2.04 1.19-3.45 <0.05
Malnourished 38 56
Immunisation status (n=63)
Fully immunized 56 55 2.76 1.62-4.62 <0.05
Partially immunized 7 19
Infant feeding* (n=27)
Exclusively breastfed 8 4 3.57 1.18-12.8 <0.05
Not exclusively breastfed 19 34
Weaning at appropriate age 12 9 2.57 0.96-5.0 >0.05
Weaning at inappropriate age 15 29
Mothers' literacy status (n=63)
Illiterate 41 52 1.27 0.77-2.09 >0.05
Literate 22 22
Overcrowding (n=63)
Present 45 55 0.86 0.5-1.44 >0.05
Absent 18 19
Birth order (n=63)
1-2 36 41 1.07 0.67-1.68 >0.05
>2 27 33
Vitamin A prophylaxis** (n=16)
With full coverage 9 6 1.50 0.70-3.1 >0.05
Without full coverage 7 7

*Infant feeding practices asked for children <2 years; **Vitamin A prophylaxis was assessed for children of 4-5 years of age.

The significantly greater rate of ARI episodes were noted among children (Table II):

  • belonging to low socio-economic class (< Rs. 1000/- per month); risk ratio - 3.19.
  • dwelling in a space where indoor atmosphere is polluted with smoke nuisance; risk ratio - 2.15.
  • having low birth weight (<2.5 kgs); risk ratio - 4.25.
  • who were not exclusively breastfed; risk ratio - 3.57.
  • who were not normally nourished; risk ratio - 2.04.
  • who were not fully immunized; risk ratio - 2.76


The noted episodic incidence of ARI, in this study, could not be compared with findings of others because of two reasons: first, most of the earlier studies concentrated more on the individuals (cases) rather than on episodes of ARI; secondly, period of observation of this study, being only 6 months, was comparatively short. Higher incidence of ARI in infants was also mentioned by other authors7,8. In consonance with the previous studies9, sex difference in incidence of ARI episodes was not significant.

Low socio-economic status, low birth weight, inadequate protection against pertussis and measles, under-nutrition, non-exclusive breastfeeding for first 4-6 months of life, intense indoor smoke pollution - all are well recognized risk factors for acute respiratory infections amongst children and their strength of associations are frequently cited in many literatures. Observations of this study were also no exception to the above. But present study failed to show any significant association between ARI episodes and some other established risk factors like inadequate vitamin A prophylaxis, overcrowding and increasing birth order of children. This might be attributed, on one hand, to small sample size across the different stratum of study population. On the other, recall bias might have played a significant role in categorization of information related to infant feeding practices, literacy status of mother and vitamin A prophylaxis coverage of the children and ultimately underestimated the effect.


The study findings strongly point towards the importance of basic health promotional measures like proper infant feeding practices, proper nutrition of the child, improved general conditions of living in prevention and control of ARI.


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  2. Tandon BN (1990). Monograph on Integrated Training on National Programmes for Mother and Child Development, Delhi, Central Technical Committee on Health and Nutrition, Deptt. of Women and Child Development; Ministry of Welfare; Govt. of India.
  3. Acute Respiratory Infection - A guide for planning, Implementation and Evaluation of Control Programme within Primary Health Care; WHO; Geneva; 1986.
  4. Banerjee KB, Verghese T. Acute Respiratory Infection and its Control (in under five children); National Institute of Communicable Diseases, Govt. of India; New Delhi; 1991.
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  6. Silman AJ. Epidemiological studies: a practical guide; Combridge University Press, 1995.
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  9. Datta DK. Problems of ARI in India, ARI Mass Education Program; NIPCCD News Letter; 1987 July-Aug, 1-2.
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