Rapid Progress toward Elimination of Strongyloidiasis in North Queensland, Tropical Australia, 2000–2018

Abstract

Infection with Strongyloides stercoralis can cause life-threatening disease in immunocompromised patients. Strongyloidiasis is thought to be hyper-endemic in tropical Australia, but there are limited contemporary seroprevalence data to inform local elimination strategies. To define the temporospatial epidemiology of strongyloidiasis in Far North Queensland, tropical Australia, the serology results of 2,429 individuals tested for the infection between 2000 and 2018 were examined. The proportion of positive tests fell from 36/69 (52.2%) in 2000 to 18/222 (8.1%) in 2018 (P < 0.001). Indigenous patients were more likely to have a positive result (Odds Ratio [OR]: 3.9, 95% CI: 3.0-5.0); however, by the end of the study period, residence in a rural or remote location (OR 3.9 (95% CI: 1.2-13.0), P = 0.03) was a more important risk factor for seropositivity than Indigenous status (OR 1.1 (95% CI: 0.4-3.1) P = 0.91). Ivermectin prescription data were available for the period 2004-2018, with annual prescriptions increasing from 100 to 185 boxes (P = 0.01). The volume of ivermectin dispensed correlated negatively with seropositivity (Spearman's rho = −0.62, P = 0.02). An expanded environmental health program was implemented during the study period and likely contributed to the declining seroprevalence; however, the relative contributions of the individual components of this program are difficult to quantify. The seroprevalence of strongyloidiasis has declined markedly in this region of tropical Australia despite there being no targeted campaign to address the disease. Expanded prescription of ivermectin and public health interventions targeting the few remaining high-prevalence communities would be expected to expedite disease elimination.

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

“…The high seropositivity in regions across northern Australia, north-east NSW and northwest SA confirming earlier work [5][6][7][9][10][11][12][13][14][45][46][47], likely reflected infections mainly in Aboriginal and Torres Strait Islander Australians who were infected in Australia. The high seropositivity in regions in Greater Capital Cities likely reflected mainly people who were infected in other countries: immigrants and returned international travellers including Armed Services personel [17][18][19]21,22,48].…”

The temporospatial epidemiology of rheumatic heart disease in Far North Queensland, tropical Australia 1997–2017; impact of socioeconomic status on disease burden, severity and access to care

“…This paradoxical situation is not limited to RHD. The local Indigenous population, particularly those living in remote, socioeconomically disadvantaged locations bear a disproportionate burden of both infectious and non-communicable diseases, but also has less access to sophisticated healthcare [ 14 , 16 , 28 – 33 ]. And this captures the essence of the challenges in addressing the life expectancy gap between Indigenous and non-Indigenous Australians.…”

“…Greater construction and improved maintenance of housing is one of the key initiatives of this program which also addresses sanitation, vector control, food hygiene and animal management [ 39 ]. There are some data to suggest that these environmental interventions are beginning to have an impact with the rates of leprosy and strongyloidiasis declining sharply in the region during this period [ 14 , 15 ]. However, these infections are arguably far easier to address than GAS which are part of the normal human skin flora.…”

“…No fewer than 17% of the local population identify as Indigenous Australians, almost half of whom report Torres Strait Islander heritage [ 13 ]. Evolving prosperity and public health interventions have seen the elimination of malaria and filariasis in the region, while the incidence of several others–including hepatitis B, strongyloidiasis and leprosy–is in steep decline [ 14 – 16 ]. However it is also a region which still contains 3 of the 10 most socio-economically disadvantaged local government areas in Australia, all 3 are communities with a predominantly Indigenous population [ 17 ].…”

Melioidosis–a disease of socioeconomic disadvantage

“…This current study's data lead to the greater truth that while almost all the patients in this cohort presented PLOS NEGLECTED TROPICAL DISEASES acutely, their clinical presentation and death from melioidosis was, in many cases, decades in the making. Despite Australia's universal health system, this finding is not unique to melioidosis; an association with socioeconomic disadvantage is seen in a variety of infectious diseases and non-communicable diseases seen in the region [13,[26][27][28][29][30][31][32].…”