A case control study investigating factors associated with high infant death in Saiha district of Mizoram, India bordering Myanmar

Infant mortality rate (IMR) in a population specific to a year is defined as the number of deaths in children <1 year of age per 1000 live births occurring in the same year. The rate, historically regarded as a good proxy measure of population health, has been shown to bear strong association with other comprehensive measures of people’s health such as disability adjusted life expectancy [1]. Although India has witnessed a fast decline [2] in IMR in the recent past - an impressive average drop of 4.56% per year over the last 5 years - concerns have been raised on substantial differences in achievement in this regard between regions within the country and even between districts within a State [3, 4].

Mizoram, one of the eight northeastern Indian states, shares international border with Myanmar on its east and Bangladesh on the west (Fig. 1). The crude death rate, the crude birth rate and the total fertility rate of Mizoram are below the corresponding national averages, thereby indicating a better health status in the state [5]. IMR in Mizoram varied from 30 to 37 per 1000 live births during 2012 to 2015. However disaggregated data revealed that among nine districts of Mizoram, Saiha, the southernmost district, had astonishingly high IMR of 113 per 1000 live births in the year 2014–2015 [6]. Qualitative interviews with mothers of a few deceased children by an Indian Council of Medical Research (ICMR) regional research centre during preliminary investigation in March, 2015 highlighted issues around meningitis, pneumonia, and septicemia as the probable causes of infant deaths. The report of this inquiry also mentioned about poor environmental hygiene and highlighted lack of skilled health care staff at Saiha district hospital.

We, on behalf of the National Institute of Cholera & Enteric Diseases (NICED), a premier institute of ICMR located in Kolkata, undertook a wider and in-depth community based investigation to explore issues around high infant mortality in Saiha. This was carried out at the behest of the Department of Health Research, Ministry of Health & Family Welfare and the Ministry of Tribal Affairs, Government of India. Rapid situation and response assessment (RSRA) technique [7, 8] was employed. The overall purpose of our investigation was to identify factors associated with infant mortality in this remote corner of the country and to inform the state health authority about intervention measures. NICED had ethical approval from the ‘Institutional Ethics Committee, National Institute of Cholera & Enteric Diseases’ as well as approval from the district health authority of Saiha for undertaking this research.

The present investigation has been able to identify factors associated with infant mortality in the southernmost district of Saiha in Mizoram, India and have implications for intervention development. We explored both distantly located as well as factors proximal to the event of infant deaths. ‘Low birth weight’ and ‘child delivery at home’ have been found in our study to be associated with experience of infant deaths in mothers. These findings are on par with the large nationally representative mortality survey examining 10892 deaths in neonates and 12260 deaths in children aged 1–59 months. Three causes accounted for 78% of all neonatal deaths in this national survey, a) prematurity and low birth weight, b) neonatal infections comprising pneumonia, sepsis and central nervous system infections and c) birth asphyxia and birth trauma [9].

We did not identify any difference between case and control groups regarding ‘exclusive breastfeeding practices’. More than 4/5th mothers in both the groups fed their children exclusively on breast during the first 6 months of life. Systematic review and critical appraisals have clearly underscored the benefits of early and exclusive breast feeding in reducing neonatal and childhood mortality resulting from various infections [10, 11].

Although mothers’ education as one of the distant and structural factors, was associated in our study, with infant death in uni-variate analysis, it was not independently associated with the outcome of interest in conditional logistic regression. Contrastingly a large population-based study in Nepal reported such association [12] and identified the protective role of maternal and paternal education against early infant death (within 24 weeks of life). Moreover, a geospatial analysis in India reported that geographic regions, which were underprivileged in child nutrition or wealth or female literacy, were also likely to be disadvantaged in terms of infant and child survival irrespective of the state to which they belonged [3]. It is important to recognize in this regard that most of the 1399 km² terrain of Saiha district is hilly and travel by road from the capital city of Aizawl (about 360 km away) takes 12 h [13]. Moreover of the nine districts of Mizoram (Fig. 1), Saiha and the neighbouring district of Lawngtlai in the south rank lowest in human development index [5].

Pneumonia, meningitis, diarrhoea and septicaemia were the top four causes of infant death in Saiha as revealed through secondary data analysis. A limited follow up survey conducted over a period of 3 days in 550 children aged ≤5 years in the township of Saiha during the present investigation also revealed 23 cases of diarrhoea. A test-strip based rapid diagnostic method identified presence of rotavirus and adenovirus in about one third of these stool specimens [14]. One fourth of the stool specimens had presence of both rotavirus and adenovirus.

It was intriguing to observe a dose response relationship between ‘per day intake of raw areca nuts’ by mothers while pregnant and subsequent infant deaths. Four or more kuhva intake per day during pregnancy was associated with infant death in present investigation. Literature review also highlights ill effects of areca nut on health [15] and fewer benefits [16]. Cardiovascular, cerebro-vascular, hepatic and metabolic disorders including type 2 diabetes mellitus were some of the health hazards that we came across during this search. Association of oesophageal inflammation and fibrosis, respiratory discomfort, renal impairment and adverse birth outcome have also been on record [15, 17]. We underscore that the issue needs further exploration as experiments in mice have revealed toxic effects of arecoline (the choline-ester present in areca nut) on embryogenesis [18]. The World Health Organization (WHO) maintains that mild thiamine deficiency can be seen in people who have high carbohydrate and low thiamine intakes in emergency situations e.g. in individuals whose staple food is polished rice, especially if their diet contains anti-thiamine factors such as tea, coffee, betel nuts and raw fermented fish. The document also highlights the link [19] between population level thiamine deficiency and infant deaths mostly occurring between 2nd and 5th month of life. It is important to note that as per NHM record, about a third of the infant deaths in Saiha was contributed by neonates (≤4 weeks), which could therefore be linked to causes other than thiamine deficiency.

Interestingly, betel nut consumption among pregnant women has been found to be associated with folate deficiency in the neighbouring country of Bangladesh. The author of this study duly highlighted the link of such deficiency with potential adverse pregnancy outcome [20]. On the other hand a large cohort study of 4963 pregnant women on Thai-Myanmar border did not find any association between betel nut intake and adverse pregnancy outcome. The authors [21] however specified that the Karen and Burmese pregnant women (their study population) used lower number of ripe nuts per day - a practice very different from Papuans and Taiwanese (covered in earlier studies producing contradictory result) who reportedly used higher number of unripe nuts [22, 23].