Infant and child mortality among indigenous and in-migrant populations of Southern Mindanao, the Philippines

Abstract

This study presents the most comprehensive set of childhood mortality parameters ever assembled for a relatively unacculturated Philippine indigenous population. Recent provision of services among this population provided a rare opportunity to assess the impact of pioneering health-care efforts. The remote and politically volatile Tampakan Highlands region of the Central Mindanao Cordillera is one of the last refuges of an indigenous B'a-an population, pursuing a mixed forest economy of slash-and-bum farming, and hunting and gathering. An adjoining Foothills region is typical of many poor, rural Philippine areas: its B'la-an and in-migrant Christian Visayan residents are largely tenant farmers who are heavily indebted to absentee landowners. Attention was drawn to the Tampakan Highlands and Foothills regions because Western Mining Corporation (WMC) had identified them as within the immediate impact area of a proposed copper-gold development project. Acceptance by the Australian mining company that social impact assessment was to be part of initial negotiation procedures paved the way for comprehensive baseline data to be captured from ‘host communities’. Childhood mortality parameters were selected as the focus of this study as they constitute robust demographic barometers of health and development status. Childhood mortality levels, patterns, trends and predictors were estimated for Highlands and Foothills populations from reproductive history and other demographic data collected from 782 women in 1998 through a single-round house-to-house survey. In order to identify all women eligible for interview, the first census of the study area was undertaken, with a total of 5,044 people enumerated across 916 households. For the overall reference period, 1983-97, approximately one in four Highlands B'a-an children were estimated to have died before their fifth birthday; a mortality level which was over 50 per cent higher than that of Foothills B'a-an children. In the Foothills itself, a substantial mortality differential was found by ethnicity: B'la-an under-five mortality was nearly three times as severe as the Visayan estimate. The comparative disadvantage of B'la-an peoples, especially Highlanders, was also captured by a host of other sociodemographic indicators. Most notably, stark regional and ethnic differentials applied to women’s education levels and mothers’ use of reproductive and child health services. In meeting contractual agreements, WMC consolidated health service delivery in the study area in the mid-1990s, with the funding and establishment of clinics in both regions. While limited government health services had been available throughout the 15-year reference period to Foothills residents, WMC’s initiatives meant that the Highlands B ’la-an enclave had access to health-care for the first time. All three ethnic sub-populations made especially impressive and almost uniform gains in child survivorship over the interval 1988-92 to 1993-97. In a departure from Foothills Visayan mortality trends, however, Foothills B ’la-an and Highlands B ’la-an populations exhibited surprisingly similar increases in child mortality over the more distant interval under investigation (1983-87 to 1988-92). Such fluctuations reflect the periodic nature of measles epidemics in the study area: cause-of-death data identify measles as having been responsible for two-fifths of Foothills B ’la-an and one-half of Highlands B ’la-an under-five deaths over the reference period. The most severe recent measles epidemic was likely to have occurred during 1988-92; the effects of a 1997 epidemic, which was personally witnessed, were mitigated through W M C’s expanded immunisation coverage o f B ’la-an children. Vulnerability to infectious diseases and malnutrition especially after weaning accounts for the quite distinctive age pattern of B ’la-an mortality. For both Foothills B ’la-an and Highlands B'la-an populations, mortality between exact ages one and five (4q1) outstripped that in infancy (1q0) and, more specifically, mortality in late childhood ( 3q2,) surpassed that o f early childhood (1q1,). Due to the B'la-an contribution to regional mortality patterns, a comparison of direct childhood mortality parameters with those derived indirectly demonstrated existing mortality models to be poorly representative of Foothills and Highlands mortality regimes. At the national level, a similar age pattern of mortality has been found only to describe sub-Saharan African countries, which are also characterised by extreme socioeconomic disadvantage. It has long been recognised that mortality models do not adequately capture the sub-Saharan childhood mortality experience. It is proposed that the malnutrition-infectious disease syndrome, which exacts extremely high death tolls in young children of socioeconomically deprived contemporary populations, would not have been a feature of the causal structure of childhood mortality among pre-contact forest populations. In the study area, population pressures brought about by Visayan in-migration have resulted in erosion of food resources and environmental sanitary conditions, and increased exposure to infectious diseases among indigenous inhabitants. This study clearly highlights the need to afford B'la-an populations priority consideration in any efforts to control factors adversely affecting child survival. The Highlands B'la-an enclave, in particular, are currently denied the most basic requirements for a healthy life.