Since white settlement, Australian Aborigines have experi-enced social changes that have had major implications for theirculture and their health. Although there has been ongoingsurveillance of health problems in indigenous communities,including health surveys to document the prevalence of manyillnesses,1 the aetiology of respiratory illness in indigenouspeople has not been widely explored. In this article, we reviewthe burden of respiratory illness in remote and non-remoteAboriginal communities and examine whether there is anyevidence of aetiology that could be useful for planning preven-tive interventions and better health care.

RESPIRATORY MORTALITY

Deaths from respiratory illnesses have been an important,ongoing health problem in Aboriginal communities. Reliablestatistics of standardized mortality rates from respiratoryillnesses have been collected since 1984, but only in WesternAustralia and the Northern Territory. These show that respira-tory diseases are one of the most common causes of mortalityin indigenous people. Taken together, cardiovascular, respira-tory and endocrine disease, plus injuries, are responsible foralmost 70% of indigenous deaths.2 As a result, the estimatedlife expectancy for indigenous Australians is approximately 20 years less than for non-indigenous people.3

In the last 25 years, respiratory mortality in Aborigines hasbeen five times higher than in non-indigenous communities.2

Much of this mortality can be attributed to respiratory infec-tions and chronic obstructive lung disease although lung canceris now emerging as a significant factor.4 Although mortalityrates in Aboriginal infants have fallen in recent years, mortalityrates in young and middle-aged Aborigines have continued at ahigh level. Thus, there has been no overall reduction in indige-nous mortality in the last two decades. Failure to reduce thesehigh rates is in contrast with significant reductions in NewZealand Maori deaths that have been achieved in the last 30 years, largely by preventing deaths from asthma attacks.2

HISTORICAL EVIDENCE OF RESPIRATORYILLNESS IN REMOTE COMMUNITIES

It seems reasonable to assume that mortality rates before whitesettlement would have been high in Aborigines in all agegroups, especially during infancy. However, no anecdotalevidence of prevalent respiratory illnesses was recorded inAborigines during the period of white settlement5 or in Aborig-ines living a traditional lifestyle in Arnhem Land in the 1950s.6

One of the earliest epidemiological surveys on the health ofindigenous people was conducted in the 1960s in over 300Aborigines living in two remote settlements in South and

J. Paediatr. Child Health (2001) 37, 108–112

Review Article

Impact and aetiology of respiratory infections, asthmaand airway disease in Australian Aborigines

JK PEAT1 and A VEALE2

1Department of Paediatrics and Child Health, University of Sydney, Sydney, New South Wales, 2Department of ThoracicMedicine, The Queen Elizabeth Hospital, Adelaide, South Australia, Australia

Abstract: In this review, we describe the burden of respiratory illness in Australian indigenous communities and examineevidence of aetiology. We have reviewed the results from studies of respiratory infections and asthma-like symptomsconducted in remote and non-remote indigenous communities and contrasted them with data from comparable studies innon-indigenous communities. Although bias cannot be controlled and generalizability is an issue, the data are the only infor-mation available and, as such, provide a basis for a hypothesis generating approach to better health care. The evidencesuggests that many indigenous people, especially those who live in non-remote regions, have asthma-like symptoms that arelargely of an infectious rather than an allergic origin. Moreover, indigenous communities continue to be exposed to lowimmunisation rates, to have low rates of breastfeeding and to have high rates of cigarette smoking, all of which have thepotential to increase the prevalence of respiratory illnesses. It is important to identify the most effective treatments andpreventive strategies for respiratory symptoms that are prevalent in indigenous children. Respiratory symptoms that arelargely of a bacterial–infectious origin may not benefit from commonly prescribed asthma therapies and, without appropriatetreatment, may lead to ongoing health problems.

Key words: asthma; indigenous; respiratory infection.

Correspondence: Associate Professor JK Peat, Clinical Epidemiology Unit, New Children’s Hospital, Parramatta, NSW 2124, Australia.Email: jennifp2@nch.edu.au

Accepted for publication 20 October 2000.

109Asthma in Aborigines

Western Australia.7 At that time, many indigenous people werehoused in dormitory-like accommodation that facilitated thespread of infections.8 In the two communities surveyed,approximately two-thirds of adults and one-third of childrenwere found to have a current, loose cough. In recent arrivals tothe settlements, rates were as high as 80% and more than 50%of children had a history of use of antibiotic therapy for res-piratory tract infections. Although these rates of respiratoryinfections were exceptionally high, no asthma or allergicsymptoms were recorded.

One decade later, a further survey of respiratory health wasconducted in over 730 Aboriginal adults and children who wereall living in humpies or low standard housing in Bourke, NewSouth Wales (NSW).9,10 Infection rates in this community were also high. Almost two-thirds of children under the age of5 years and one-fifth of older children had recently had anupper respiratory tract infection. Moreover, bronchitis, respira-tory tract infection or tuberculosis was found in 25% of adultmen and 19% of adult women. However, asthma was reportedin only five adults and in none of the children.

In 1983, a high prevalence of respiratory infections was alsorecorded in a study of the respiratory health of 1287 indigenouspeople living in Western Australia.11 One in five children, aged0–4 years, had a purulent nasal discharge and one in five children,aged 5–9 years, had a current loose cough. As in the othercommunities, asthma was not mentioned as a health problem.

RESPIRATORY INFECTIONS

Respiratory infections have remained a major health problem inAboriginal communities, with high rates of upper and lower res-piratory infections in remote regions. Aboriginal children livingin central Australia have very high incidence rates of invasivepneumoccocal disease, with infection rates of 60–80 times higherthan in the USA or European countries.12 Aboriginal children incentral Australia also have very high rates of acute lower respira-tory tract infections,13 and in north-eastern Australia, rates ofhospitalization for pneumonia continue to be high.14

Although lower respiratory tract infections remain theleading cause of hospitalizations in some regions, it is encour-aging that recent mortality rates are lower than in other devel-oping countries.13 There is also evidence that the severity ofinfections in Aboriginal children is decreasing, that fewerchildren are admitted to hospital than previously, and thatgrowth rates are improving.15 Nevertheless, there is continuingconcern about high rates of respiratory infections as a conse-quence of continuing poor living conditions and inadequatevaccine delivery.12 Although vaccines against respiratorypathogens such as influenza virus and Streptococcus pneumo-niae are now available, they have not yet had a major impact onrespiratory heaIth in Aboriginal communities, partly due tounder-use. It is hoped that the imminent advent of conjugatepneumococcal vaccines will have a dramatic impact on theincidence of pneumococcal pneumonia in indigenous people inthe next few years.

RECENT STUDIES IN REMOTE REGIONS

In 1991–92, an extensive health survey of asthma and allergywas undertaken in indigenous people living in four remotecommunities in Queensland, South Australia and the Northern

Territory.16 In this cross-sectional survey of over 500 childrenand 700 adults, respiratory illness was measured by question-naire, airway hyper-responsiveness (AHR) was measured byhistamine inhalation tests, and atopy was measured by skinprick tests to common allergens. Figure 1 shows that the preva-lence of asthma and allergy in these communities was higher inadults than in children, suggesting a ‘late-onset’ model ofasthmatic illness.

This pattern of acquisition of asthma and allergy is verydifferent from the pattern in non-indigenous adults andchildren in NSW, who were studied about the some time usingthe same research protocol. In non-indigenous people, asthmahad an ‘early onset’ model with a high prevalence inchildhood.17 In these communities, 25% of children hadwheeze compared with 12% of adults, and 18% had AHRcompared with 8% of adults. This suggested, either a ‘cohorteffect’ of increasing asthma prevalence with each new genera-tion of children, or that many children develop and then growout of their asthma. In these studies, the prevalence of atopywas about 40% in all age groups. Although the prevalence ofasthma was similar in indigenous and non-indigenous adults inboth studies, the prevalence of asthma and atopy were muchlower in the indigenous children living in remote communitiesthan in non-indigenous children living in urban regions.

Fig. 1 Prevalence of wheeze, airway hyper-responsiveness (AHR)and atopy by age in 1252 indigenous people living in remote regions inQueensland, the Northern Territory and South Australia.16 (�), Recentwheeze; ( ), atopy; ( ), AHR.

110 JK Peat and A Veale

RESPIRATORY ILLNESS IN NON-REMOTE REGIONS

Only two studies of the respiratory health of indigenousAustralians living in non-remote regions have beenconducted, both in recent years. In 1999, the AustralianBureau of Statistics published figures from its NationalHealth Survey conducted in 1995–96 in all States and acrossall age groups.1 In the study, information was collected fromover 54 000 people of whom almost 1800 were of Aboriginalor Torres Strait Islander descent. In the information reported,data from people living in remote regions (defined as regionswith less than 57 homes per 100 square kilometres) wereexcluded.

Figure 2 shows that the trends by age group for asthma inindigenous people living in non-remote regions are verydifferent from those of indigenous people living in remoteregions as shown in Fig. 1. Not only are rates for indigenouspeople in non-remote regions higher than for non-indigenouspeople, but both ethnic groups have a similar age distributionpattern of illness, with a higher prevalence in childhood. Figure 3 shows that the use of asthma medications in theprevious 2 weeks also follows the same trends but that asthmamedication use is higher in indigenous than in non-indigenousadults.1 In previous epidemiological studies, we have foundthat children who are reported to use asthma medicationsmostly use bronchodilators, with less than 10% using preven-

tive medications such as inhaled corticosteroids.18 This trendmay be a problem if indigenous people living in urban areashave a high rate of bronchodilator use as a result of high ratesof an asthma diagnosis, although other airway diseases thatcause airflow obstruction are more prevalent and may require adifferent type of treatment.

There is anecdotal evidence to suggest that asthma inindigenous people may be less allergy driven than that of non-indigenous people. In an observational study of admissions toAlice Springs Hospital, admission rates to hospital for asthmain non-indigenous Australians peaked during the high pollenmonths but no such peak was seen for indigenousAustralians.19 The observation that Aboriginal children areless likely to be hospitalized for an exacerbation of asthmathan non-Aboriginal children20 also suggests that ‘asthmatic’symptoms may have a different course and aetiology in thetwo ethnic groups.

RISK FACTORS FOR ASTHMA

The major preventable risk factors for asthma in non-indigenous children are atopy to inhaled allergens, exposure to parental tobacco smoke, a low omega-3 fatty acid diet, andearly introduction of cow’s milk formula feeding.21,22 In Aus-tralia, rates of breastfeeding are in the range of those found in

Fig. 2 Prevalence of recent and/or long-term asthma in approxi-mately 1800 indigenous and 52 000 non-indigenous people living innon-remote regions throughout Australia.1 ( ), Indigenous; (�), non-indigenous.

Fig. 3 Prevalence of asthma medication use in previous 2 weeksasthma in approximately 1800 indigenous and 52 000 non-indigenouspeople living in non-remote regions throughout Australia.1 ( ),Indigenous; (�), non-indigenous.

the UK and the USA, but are much lower than in someEuropean countries,23 with similar rates in indigenous and non-indigenous people.1,24 Approximately 10% of Australianchildren are not breastfed at 4 weeks of age and a further30–40% stop being breastfed between 4 and 23 weeks of age,although breastfeeding rates are likely to be much higher inremote regions.

Parental smoking is an important risk factor for children tohave symptoms of wheeze and asthma or respiratory infectionsin early life.25 Rates of adult smoking and the resultantexposure of children to environmental tobacco smoke arehigher in indigenous than in non-indigenous communities. Insome indigenous communities, as many as 40–80% of adultssmoke.9,26,27 In the Australian Bureau of Statistics survey,over 40% of indigenous women were current smokers com-pared to 20% of non-indigenous women, and only 32% ofindigenous women were never smokers compared to 56% of non-indigenous women.1 In some populations, rates ofsmoking are even higher.24 These high rates of smoking are amajor health concern and suggest that effective preventivestrategies will have the potential to lead to improvements inmany health outcomes.

The so-called ‘hygiene-hypothesis’ builds on evidence thatbacterial infections in early life may protect children againstdeveloping asthma by driving the immune system into a T-helper 1 (Th1) pathway and thereby protecting against theability to mount atopic responses to common inhaledallergens.28 This may be one explanation why indigenouschildren living in remote communities have little asthma, butdoes not help to explain why indigenous children in non-remote regions have high rates of asthma symptoms. Asthma isa complex disease entity with many causal pathways. Whilstthere is evidence that early infections may prevent asthma,there is also evidence that bacterial infections in early life canbe a risk factor for later symptoms.29 It is possible that repeatedrespiratory infections in early life promote the development ofairway inflammation and lability or that early infections are thefirst expression of inherent airway disease.

LUNG DISEASE IN ADULTS

Evidence from the few studies in which lung function has beenmeasured suggests that indigenous people have relatively lowlung volumes.30–32 In rural communities, lung volumes ofapparently healthy indigenous people were approximately20–30% lower than those of non-indigenous people of thesame age, height and gender.26 These values may be ‘normal’for indigenous people or they may be a consequence of adverseevents such as poor fetal nutrition.33 Because indigenouschildren are smaller than non-indigenous children of the sameage,34 they may have smaller airways which increase the likeli-hood of wheeze.35 Thus, indigenous people may have lowerlung volumes for height as do other racial groups36 or theirlower lung volumes may be a consequence of airways failing toachieve full growth potential.

In the rural communities visited, chronic obstructivepulmonary disease (COPD) was found in 12% of adult menand 5% of women. This high prevalence, which is almostcertainly a consequence of adverse life events, is approxi-mately double the rate that has been documented in non-indigenous populations.37 It is possible that a higher use ofasthma medications in indigenous adults may be, in part, due

to the use of bronchodilators for smoking-associated COPD.Because rates of smoking have increased rapidly in indige-nous populations, the rate of COPD can be expected tocontinue to increase in future years, unless effective interven-tions to reduce the high prevalence of cigarette smoking areimplemented.

LIMITATIONS OF THE EVIDENCE

There are many potential limitations to comparing evidencefrom the studies cited in this review. Both bias and generaliz-ability are an issue when comparing studies in which highresponse rates were not achieved. Studies conducted by door-knocking1 are not the most effective health surveillance methodfor Aboriginal communities. Measurements of respiratorysymptoms measured by a doctor diagnosis or based on use ofprescribed medications are always subject to misclassificationerrors because of lack of standardization between culturallydifferent communities. In some studies, bias in measuringrespiratory infections has been minimized by using screeningtests for bacterial colonization13 or evidence of asthma hasbeen validated by objective tests of airway responsiveness.16

However, the majority of studies have relied on subjectivequestionnaire measurements. Despite these inherent problems,the data from the available studies are important for assessingcurrent levels of morbidity and health care practices, and fordeveloping more rigorous studies to test models of better healthcare.

CONCLUSIONS

The epidemiological evidence suggests that rates of respiratoryillnesses, that are largely a result of bacterial infections, remainunacceptably high in indigenous people living in remotecommunities. Although rates of asthma are low in indigenouschildren living in remote communities, rates of asthma-likesymptoms and asthma medication use seem particularly high inindigenous children and adults living in non-remote communi-ties. However, the accumulating evidence suggests that manyof these symptoms may have an infectious rather than anallergic origin. It is possible that many episodes of wheeze inindigenous children and adults are a result of inherently smallairways that are further compromised by repeated or prolongedbacterial infections or, in adults, by cigarette smoking. Themisinterpretation of asthma-like symptoms in indigenouscommunities as being of an allergic origin may be leading tohigh, and possibly inappropriate, rates of use of asthmatherapies.

It is clear that interventions to prevent respiratory infections,to increase breastfeeding and to reduce cigarette smokingshould be primary health goals in indigenous communities.The high numbers of indigenous children who are exposed tothese risk factors, which have the potential to increase allergicand infectious respiratory illness, is a major concern. In theshort term, there is an urgent need to identify the aetiology andthe most effective treatments for asthma-like respiratorysymptoms in indigenous children that may be a consequence ofbacterial infections, that may not respond well to asthmatherapy, and that may require more appropriate treatment toprevent adverse long-term outcomes.

111Asthma in Aborigines

112 JK Peat and A Veale

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