Environmental Background - Michael Gracey

Enteropathy - Renata Kukuruzovic

Michael Gracey. School of Public Health, Curtin University; Office of Aboriginal Health, Health Department of Western Australia; and International Pediatric Association

The infants and children of the Indigenous people of Australia, the Aborigines and Torres Strait Islanders, have much higher rates of incidence, prevalence and more severe infections than the non-Indigenous population. They also have much higher rates of hospitalisation for these conditions and more complications or morbidity after their episodes of infection. The reasons for these inequities in health are complex and have been present for many decades. To understand the dynamics of this problem requires knowledge of the pre-history of Indigenous Australians and the impact of European colonisation on their way of life. In many parts of northern and central Australia the living conditions under which they now live are squalid, crowded and heavily contaminated with pathogenic micro-organisms. Their health infrastructure services, such as clean water, sewage and waste disposal, are often lacking and in many remote locations it is very difficult to provide regular and adequate primary health services as well as referral services, when necessary. This has to be done in ways that are culturally appropriate. Provision of regular fresh food is often extremely difficult and undernutrition is endemic. The inappropriate use of expensive artificial breast-milk substitutes and the increasingly widespread use of "Westernised" diets are also potentially harmful, nutritionally. Poor maternal nutrition also has very significant impacts on fetal and infant health, perhaps with long-term consequences. Living in environments that are heavily contaminated, microbiologically, has deleterious effects on the gastrointestinal tract; this can cause maldigestion, malabsorption and a worsening of nutrition and growth. Infections with a wide range of intestinal pathogens and parasites are very common in these children and are often associated with other infections, particularly respiratory infections. This leads to a "vicious circle" of infections – malnutrition – infections. In order for strategies to overcome this problem to be successful, they need to be multi-faceted. The following need to be addressed: socio-economic disadvantage, general education and employment, health education and promotion, involvement of Indigenous people in health services, and the provision of health services by "mainstream" that are adapted to the special needs of Indigenous people, particularly in remote areas. Nutrition and diarrhoeal disease have a very important place in this challenge. This needs urgent inter-sectoral attention to programmes that will improve housing, hygiene practices and the provision of high standards of environmental health over vast distances and areas. High standards of clinical care must be available to all citizens who live in northern Australia in order to meet this challenge.

Kukuruzovic RH, Haase A, Dunn K, Bright A, Brewster DR. Northern Territory Clinical School, Darwin, Australia.

Background- Diarrhoeal disease in young Aboriginal children is associated with increased complications such as lactose intolerance, acidosis, hypokalaemia and prolonged hospital admissions. We hypothesised that Aboriginal children have underlying mucosal damage (tropical/environmental enteropathy) contributed to by living in a contaminated environment and having recurrent diarrhoeal infections. Damage to the villi in the small intestine results in the loss of the enzyme lactase predisposing to osmotic diarrhoea in young children whose staple diet is milk. Intestinal permeability tests using the sugars lactulose and rhamnose are a validated test of small bowel mucosal function. The dual sugar test was used to assess if a tropical/environmental enteropathy was present in asymptomatic Aboriginal children and if so, if this predisposed to greater complications with acute diarrhoea.

Methods- A prospective descriptive study at a referral hospital in the Northern Territory. We studied 264 admissions of Aboriginal children with diarrhoea and 74 without diarrhoea (controls), and compared them to a sample of non-Aboriginal children, 21 with diarrhoea and 16 true controls. A timed 90-minute blood sample was taken after the oral administration of 5g lactulose (disaccharide) and 1g rhamnose (monosaccharide) in a 100mL isotonic solution. High Performance Liquid Chromatography (HPLC) analysis was carried out on the blood specimen using the Dionex DX500 system. Samples were collected on day 1 and day 5 of hospitalisation when feasible.

Results- Aboriginal vs non-Aboriginal diarrhoeal admissions, respectively, had geometric mean lengths of stay of 8.8 vs 4.1 days (P<0.001), a mean of 5.0% vs 3.5% dehydration (P=0.01), were acidotic in 64% vs 23% (P<0.001) and had hypokalaemia in 69% vs 12% (P<0.001). In Aboriginal children, geometric mean L/R ratios with diarrhoea were 16.4 (14.4 to 18.6) on admission and 7.1 (6.0-8.4) on day five vs 4.6 (3.8 to 5.6) for controls, compared to 7.9 (4.7 to 13.1) in non-Aboriginals with diarrhoea vs 2.5 (1.9-3.1) in true controls. High L/R ratios were from impaired mucosal barrier function (increased passage of lactulose) in Aboriginal children who had geometric mean % recovery of lactulose of 8.3 (7.2 to 9.6) compared to non-Aboriginals, 3.2 (1.7 to 5.8). On multiple regression, the factors independently associated with high L/R ratios were diarrhoeal severity (P<0.001), acidosis (P<0.001) and breastfeeding (P=0.001).

Conclusions- Interventions to improve hygiene and overcrowded living conditions in Aboriginal communities should receive high priority in order to improve tropical-environmental enteropathy and severe mucosal damage in gastroenteritis.

Susan Sayers. Menzies School of Health Research, Darwin NT

In 1987 an Aboriginal Birth Cohort Study was commenced with the aims of describing Aboriginal birth size by weight, length and gestation age to investigate the influences of perinatal outcomes on childhood morbidity, growth and nutrition. These aims were later expanded to include potential markers of adult diseases in childhood. 1238 live born singletons were born in the Royal Darwin Hospital between Jan 1987 and March 1990 to mothers who were recorded as Aboriginal in the Delivery Suite Register. The 504 routine deliveries from the Darwin Health Region who had a post-natal gestational age estimation, had a mean birth weight 3085 grams ± 600grams with a mean gestational age 39 weeks. 13.8 % were LBW (<2500grams), 7% were preterm (<37 weeks ) and 25% were small for gestational age (SGA) (Guaran et al.1994). Of the 123 SGA babies with available ponderal index data (weight/length³), 59% were symmetrically small. Between December 1998 and 2001, children from the cohort have been traced and selected measures including growth and nutrition have been taken according to standard procedures. Five children died before the follow-up. To date there is an 87% follow up of living children with no significant differences in birth weight, sex ratio and gestational age between those not yet assessed and those assessed.

Preliminary results at cross sectional follow up: The mean age was 11.4 years, 50% were male and 34% had commenced puberty. The mean weight was 35kg, the mean height 143 cm, and the mean BMI was 16.8 kg/m². Although there were no significant differences in mean age, sex ratio, puberty status, or place of residence, there were significant differences between SGA children and AGA children for all parameters of growth and nutrition measured. Being LBW, preterm, or ponderal index< 10^th (Miller and Hassanein 1971) did not influence childhood outcomes of nutrition and growth. There were significant differences in growth and nutrition between urban (92) and rural (311) children with no significant differences in mean age, puberty status and sex ratio. There were no stunted children (HAZ -2.0) in the urban group, 20% were classified overweight (Cole et al. 2000) and 7.7% obese. For rural children 8.7% were stunted with 5.8% overweight and 1.6% obese.

Conclusions: These preliminary findings show for this cohort, children born small for gestational age are more likely to remain small and according to place of residence there is an heterogeneity of the Aboriginal child population, which has important implications for public health interventions.

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2. Miller H and Hassanein K 1971 Diagnosis of impaired fetal growth in newborn infants.
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4. Cole TJ, Bellizi MC, Flegal KM and Dietz WH. 2000 Establishing a standard definition for child overweight and obesity worldwide: international survey. British Medical Journal 320:1240-1243.