Seropositivity and geographical distribution of Strongyloides stercoralis in Australia: A study of pathology laboratory data from 2012–2016

Abstract

Background There are no national prevalence studies of Strongyloides stercoralis infection in Australia, although it is known to be endemic in northern Australia and is reported in high risk groups such as immigrants and returned travellers. We aimed to determine the seropositivity (number positive per 100,000 of population and percent positive of those tested) and geographical distribution of S. stercoralis by using data from pathology laboratories. Methodology We contacted all seven Australian laboratories that undertake Strongyloides serological (ELISA antibody) testing to request de-identified data from 2012–2016 inclusive. Six responded. One provided positive data only. The number of people positive, number negative and number tested per 100,000 of population (Australian Bureau of Statistics data) were calculated including for each state/territory, each Australian Bureau of Statistics Statistical Area Level 3 (region), and each suburb/town/community/locality. The data was summarized and expressed as maps of Australia and Greater Capital Cities. Principal findings We obtained data for 81,777 people who underwent serological testing for Strongyloides infection, 631 of whom were from a laboratory that provided positive data only. Overall, 32 (95% CI: 31, 33) people per 100,000 of population were seropositive, ranging between 23/100,000 (95% CI: 19, 29) (Tasmania) and 489/100,000 population (95%CI: 462, 517) (Northern Territory). Positive cases were detected across all states and territories, with the highest (260-996/100,000 and 17–40% of those tested) in regions across northern Australia, north-east New South Wales and north-west South Australia. Some regions in Greater Capital Cities also had a high seropositivity (112-188/100,000 and 17–20% of those tested). Relatively more males than females tested positive. Relatively more adults than children tested positive. Children were under-represented in the data. Conclusions/Significance The study confirms that substantial numbers of S. stercoralis infections occur in Australia and provides data to inform public health planning.

Seroepidemiology of Strongyloides spp. Infection in Balimo, Western Province, Papua New Guinea

“…Cutoff ranges were adopted from laboratory standards in Western Australia. 31 Intermediate results were grouped with negative results to avoid overestimating the prevalence of strongyloidiasis.…”

Neglected tropical diseases in Australia: a narrative review

“…The true prevalence and burden of strongyloidiasis in Australia is unclear, due to the large number of asymptomatic cases, underdiagnosis, and limited surveillance data 51 . There have been recent calls for strongyloidiasis to be made a nationally notifiable disease in order to improve surveillance and inform the planning, implementation, and evaluation of control measures 48,51 …”

“…39,40 Strongyloidiasis is endemic in parts of Australia, predominantly occurring in remote Aboriginal and Torres Strait Islander communities in tropical areas of WA, the NT, Queensland, northern South Australia, and northern NSW (Box 2). 27,[41][42][43][44][45][46][47][48] A limited number of epidemiological surveys, both retrospective and prospective, have been undertaken in Australia, reporting highly variable prevalence (0-60%). 42,[48][49][50] The true prevalence and burden of strongyloidiasis in Australia is unclear, due to the large number of asymptomatic cases, underdiagnosis, and limited surveillance data.…”

“…27,[41][42][43][44][45][46][47][48] A limited number of epidemiological surveys, both retrospective and prospective, have been undertaken in Australia, reporting highly variable prevalence (0-60%). 42,[48][49][50] The true prevalence and burden of strongyloidiasis in Australia is unclear, due to the large number of asymptomatic cases, underdiagnosis, and limited surveillance data. 51 There have been recent calls for strongyloidiasis to be made a nationally notifiable disease in order to improve surveillance and inform the planning, implementation, and evaluation of control measures.…”

“…51 There have been recent calls for strongyloidiasis to be made a nationally notifiable disease in order to improve surveillance and inform the planning, implementation, and evaluation of control measures. 48,51 The human T-lymphotropic virus type 1 (HTLV-1) is also endemic in remote communities, primarily in Northern Australia and is associated with bacteraemia and disseminated strongyloidiasis. 41,49 Other risk factors for S. stercoralis infection in Australian Aboriginal people include age (highest risk in school-aged children) 42,52 and malnutrition.…”