Introduction

Otitis media is one of the most common childhood infections. It is the most common diagnosis made by otolaryngologists among children in Nigeria ₁, yet its exact prevalence in many societies is not known₂.Otitis media is known to be a spectrum of disease ranging from an acute non suppurative otitis media to chronic transformation of the disease which includes chronic suppurative and nonsuppurative diseases particularly when it is not treated or partially treated ₂. Because of the wide range of presentation of the disease, most studies have been centered on the chronic nature of the disease in the tropics while there have been fewer studies on the acute nature of the discharging ears. In view of the dearth of studies on acute suppurative otitis media defined by the transient perforation of the tympanic membrane and formation of pus less than 6 weeks duration ₃, this study was conducted with the aim of bridging the perceived gap in our knowledge base by looking at incidence of the disease and various epidemiological factors associated with it in our environment.

Patients and methodology

This study is a prospective study and hospital based carried out over a one year period in the general paediatric out-patient department of a hospital in the south west of Nigeria. The study population included children aged 1 month to 14 years who presented with discharging ears less than 6weeks duration. Children who presented with ear discharges limited to the external ears were excluded from the study. The history and otoscopic examination obtained from the subjects were documented on structured questionnaires. Ethical clearance was obtained from the hospital and consent was also obtained from parents of subjects.

Result

Of the 10,303 children who visited the paediatric outpatient department over a one year period, 104 children met the inclusion criteria accounting for an incidence of 1.01%.

Gender: Of the 104 subjects in this study, 49(47.1%) were males while 55(52.9%) were females giving a slight female preponderance with a male to female ratio of 0.9:1

Figure 1

Table 1: Age specific distribution of subjects

Figure 2

Table 2: Social class distribution of parents of children in this study

Exposure to smoke: One hundred and one subjects were exposed to smoke from kerosene stove and wood smoke used for cooking within the home environment while 3(2.9%) denied exposure to this form of indoor pollution. All subjects denied indoor exposure to cigarette smoke.

Type of housing: of the 104 subject in this study, 26(25%) lived in well ventilated and not overcrowded houses (flats) while 78(75%) lived in poorly ventilated and overcrowded houses usually referred to as ‘face-to-face' in the community.

Nutritional history: Amongst the subjects whose ages were less than 24months, 44(71.1%) were still breastfeeding as at the time this study was conducted while 18(29.0%) had stopped breast feeding. The mean age at stoppage of breast feeding was 16.68+/-2.87months while the mean age at introduction of other feeds was 5.103+/-1.94months.On the other hand 54(87.1%)denied use of feeding bottles while 8(12.9%) used feeding bottles prior to presentation.

Characteristic of the disease: Unilateral disease accounted for 89(85.6%) while 15(14.4%) had bilateral disease .Ninety -three(91.2%) had central perforation while 9(8.8%) marginal/attic perforation. The tympanic membrane could not be visualised in two of the subjects.

Figure 3

Table 3: Clinical presentation of subject with ASOM

Discussion

The prevalence of ASOM in this study was 1.01%, which is lower than the 2.4% reported by Ako-Nai ₄ in a similar study conducted in a comprehensive health center. The difference may have been due to the higher denominator of patients using the health facility (Wesley Guild hospital Ilesa) where this study was conducted compared to that of Ako-Nai. This facility, which was initially a missionary hospital but now government owned delivers primary, secondary and tertiary level of care to the semi-urban populace of Ilesa and environ. Similarly the prevalence in this study is comparable to the community based study by Zakzouk who reported a prevalence of 1.05% amongst Saudi Arabian children in a nationwide survey ₅.

OM is known to be a childhood disease with high incidence in the first 3 years of life ₆.This is supported by the finding of a higher incidence in children below two years of age in this study. There was also a fall in the incidence of ASOM in the older aged children (table I).This findings is consistent with reports of other existing literature ₇, ₈ and supports the hypothesis that most adult who have otitis media must have had it when they were younger.

There was a slight female preponderance amongst children with ASOM with a male to female ratio of 0.9:1.The reason for this gender difference is not known. This finding agrees with the report of Amusa et al ₉ but contrasted with the report of Giebink and Quie₁₀ who had reported a male preponderance.

The majority of subjects in this study fell into the low socio economic group (class IV) which agrees with other existing literature ₁, ₁₁.The socio economic classification used in this study was based on the model developed by Oyedeji ₁₂ which uses educational qualification and occupation of both parents to assigned them to their social class. Poverty and poor medical seeking behavior may have contributed to the dominance of this socioeconomic group in the epidemiology of ASOM in the locality where this study was conducted. Paradoxically, fewer subjects fell into the social class V which is the lowest class. The reason may be due to extreme poverty and lack of education which characterizes this group thereby hindering them from seeking and utilizing orthodox care in hospitals in the urban area since the two subjects in this category were from surrounding villages.

Over 74% of the subjects in this study lived in overcrowded and poorly ventilated houses usually referred to as ‘face-to-face' in the community. These types of houses consist of many rooms housing many families with a central passage way in which they share same toilet, bathroom and kitchen. This type of housing which is usually overcrowded may contribute to the higher proportion of children with ASOM. Amusa in her work had reported significant association between overcrowding and Otitis media₈ while Bruneau et al ₁₃ found no association. In addition to this, most of the parents of the subjects do their cooking with kerosene and wood indoor thereby exposing the subject to noxious agents from the biomass smoke which is known to affect the respiratory epithelium thereby predisposing them to respiratory tract infection and increasing the risk of OM₁₄. Another interesting finding is that the entire subject denied exposure to cigarette smoke. The reason for this is not clear-cut, but it may not be unconnected with the aggressive campaign of the government on the dangers of smoking to the health of the individual in the community.

Among subjects less than 24 month of age in this study, 71.1% were still breast feeding at the time of presentation and mean age at stopping breast feeding was 16.68+/-2.87 months with 87.1% denying the use of bottle feeding. It was also interesting that most of the children were exclusively breast fed for almost 6 months as recommended by world Health Organization (mean age at which other feed were introduced was 5.103+/-1.94 month).These findings tend to contrast with other existing literature who had reported a reduction in the incidence of OM in children who were breastfed ₁₅, ₁₆, ₁₇and put to question the protective effect of breast milk as postulated by Newburg ₁₇.

Unilateral disease with central perforation was more common compared to bilateral diseases and marginal perforation in this study. The reason for this difference is not clear. This agrees with other existing literature which had reported similar findings in chronics suppurative otitis media ₆.

Other associated clinical features of ASOM in this study includes fever (46.2%), ear pain (38.5%), URTI(51.9%) and enlarged tonsils(35.6%).A slightly higher proportion of subject presented with signs and symptoms of URTI which agrees with other existing literatures who had reported that URTI increases the risk of OM. Ruuskanem reported a strong correlation between AOM and viral respiratory infections ₁₈. Also, the proportion of subject with fever in this study cannot be explained solely by ASOM bearing in mind that this study was conducted in a region endemic for malaria for which some were treated. Amusa had reported incidence of AOM to be 29% amongst febrile children in the tropics ₉.

In conclusion, higher proportion of subjects with ASOM practiced exclusive and prolonged breastfeeding as advocated by world Health Organization, belonged to the low socioeconomic class, lived in poorly ventilated and overcrowded houses and were exposed to indoor pollution. Further studies to confirm these factors as risk factors for the disease in this locality are advocated.

Acknowledgement