Strongyloidiasis - A nested, matched, case control study

  • Emily Bowden

    Student thesis: Coursework Masters - CDU


    Strongyloidiasis is a soil transmitted helminth infection caused by the parasitic nematode Strongyloides stercoralis. The disease is generally associated with socio-economic disadvantage and poor living conditions. Strongyloidiasis is prevalent in many rural and remote Aboriginal communities in northern and central Australia. In developing countries mass drug administration (MDA) is an accepted way to treat parasitic infections.
    The purpose of this study was to review the published evidence concerning the effectiveness of MDA and to determine if there was a difference in primary health care (PHC) presentations before and after an ivermectin MDA in a remoteAustralian Aboriginal community.

    A nested matched case-control study was conducted using data collected from352 participants (cases n=176, controls n=176) aged between 5-74 years livingin a remote Northern Territory (NT) Aboriginal community. The participants wereenrolled in a two year ivermectin mass drug administration project thatcommenced in 2010 to reduce the prevalence of scabies and strongyloidiasis. Clinical information on PHC presentations that occurred 12 months prior to the date of the 2010 Strongyloides result (pre MDA) and 12 months after the result date (post MDA) was extracted from the electronic health record system used by the PHC service.

    There were 176 participants (cases) with a positive Strongyloides result in 2010 that were matched by age and sex with participants who had a negative Strongyloides result (controls). The median age was 20 years (IQR 12 – 29) withsignificantly more males diagnosed with strongyloidiasis than females (28% v’s 22%, p=0.01).

    There was no difference in the odds of cases presenting to the PHC servicethan controls with any of the five symptoms commonly associated withstrongyloidiasis pre MDA (OR 0.71, CI 95% 0.44,1.14) or post MDA (OR 0.64,CI 95% 0.40,1.28).However, controls had a significantly greater proportion ofsymptomatic presentations to the PHC service than cases pre MDA (12%v’s16%, p<0.05 respectively) but not post MDA (15% v’s17%, p>0.05respectively). For the types of PHC presentations (well person, infectious or unwell presentation), the odds of a strongyloidiasis case having a well person or unwell presentation pre MDA was almost half that of controls (well person OR0.47, CI 95% 0.29,0.76, unwell 0.46, CI 95% 0.29,0.72),

    Strongyloidiasis cases had significantly less PHC presentations than controls inthe 12 months prior to being screened and receiving the ivermectin MDA, and inthe 12 months following MDA. PHC presentations with symptoms associated with strongyloidiasis did not change after the MDA and were greater for controlsboth pre and post MDA. From this study, there is no evidence to suggest a benefit to this community of further MDA with ivermectin for the treatment or prevention of strongyloidiasis if using the presence of symptoms and presentations to PHC as measures of morbidity.

    Date of Award2016
    Original languageEnglish
    SupervisorTherese Kearns (Supervisor) & Linda Ward (Supervisor)

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