Strongyloidiasis in Auckland: A ten-year retrospective study of diagnosis, treatment and outcomes of a predominantly Polynesian and Fijian migrant cohort

PLoS Negl Trop Dis. 2024 Mar 28;18(3):e0012045. doi: 10.1371/journal.pntd.0012045. eCollection 2024 Mar.

Abstract

Background: Strongyloides stercoralis is not endemic in Aotearoa New Zealand (AoNZ). However, approximately one third of Auckland residents are born in endemic countries. This study aimed to describe the epidemiology and management of strongyloidiasis in Auckland, with a focus on migrants from Pacific Island Countries and Territories.

Methods: This study retrospectively reviewed clinical, laboratory and pharmacy records data for all people diagnosed with strongyloidiasis in the Auckland region between July 2012 and June 2022. People with negative Strongyloides serology were included to estimate seropositivity rate by country of birth.

Findings: Over ten years, 691 people were diagnosed with strongyloidiasis. Most diagnoses were made by serology alone (622, 90%). The median age was 63 years (range 15-92), 500 (72%) were male, and the majority were born in Polynesia (350, 51%), Fiji (130, 19%) or were of Pasifika ethnicity (an additional 7%). Twelve participants (1.7%) had severe strongyloidiasis at diagnosis. The total proportion treated with ivermectin was only 70% (484/691), with no differences between immunocompromised and immunocompetent participants, nor by ethnicity. The outcome of treatment (based on a combination of serology and/or eosinophilia and/or stool microscopy) could only be determined in 50% of the treated cohort. One participant failed treatment with ivermectin, experiencing recurrent strongyloidiasis, and another participant died in association with severe strongyloidiasis. The rate of 'positive' Strongyloides serology was highest among participants born in Samoa (48%), Fiji (39%), and Southeast Asian countries (34%).

Interpretation: Strongyloidiasis was common and under-treated in Auckland during the study period. Clinicians should have a low threshold for considering strongyloidiasis in migrants from endemic countries, including Polynesia and Fiji.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Animals
  • Ethnicity
  • Female
  • Humans
  • Ivermectin / therapeutic use
  • Male
  • Middle Aged
  • Pacific Island People
  • Retrospective Studies
  • Southeast Asian People
  • Strongyloides stercoralis*
  • Strongyloidiasis* / diagnosis
  • Strongyloidiasis* / drug therapy
  • Strongyloidiasis* / epidemiology
  • Transients and Migrants*
  • Treatment Outcome
  • Young Adult

Substances

  • Ivermectin

Supplementary concepts

  • Fijian people
  • Samoan people

Grants and funding

This work was supported by a Summer Studentship grant, awarded to SKM by Te Whatu Ora Counties Manukau. The funder had no role in the study design, data collection, data analysis, data interpretation, writing of the report, nor decision to submit for publication.