Authors

Discussion

Background

Strongyloides stercoralis is a soil-transmitted intestinal helminth which can cause lifelong infections in humans. Symptoms of infection can vary, whilst many may be asymptomatic. When an infected host is immunocompromised, S. stercoralis has the potential to cause a ‘hyper-infection’ – a life-threatening disseminated disease with mortality up to 71%. Given treatment with anti-parasitic agents has a high eradication rate, successfully screening at-risk groups can reduce the threat of hyper-infection, particularly in those who may be immunocompromised. We conducted a systematic review and meta-analysis of S. stercoralis infections reported in the United Kingdom to describe the demographics and clinical features in those with this parasitic infection.

Methods

A systematic search of PubMed and Scopus was performed and studies describing patients in the United Kingdom with proven S. stercoralis infection were included. The outcomes studied were weighted pooled prevalence (WPP) of clinical features during illness, demographics, and relevant investigation findings. We used the DerSimonian-Laird random-effects model to report prevalence of clinical variables and a Freeman-Tukey double arcsine transformation was applied to our data.

Results

Seventeen studies with 1361 patients were analysed. A third of cases reported were in returning travellers (454/1361, 33.3%), whilst 24.5% (334/1361) were cases in migrants. A total of 342/1361 (25.1%) cases were described in Armed Personnel who had returned to the United Kingdom. A minority of cases were in those living with HIV (8/1361, 0.6%) and 223/1361 (16.4%) were cases from a mixed cohort.

The weighted pooled prevalence (WPP) of asymptomatic cases was 31.0% [95%CI 27.5% - 34.6%, I²=92.3%]. The most reported symptoms were abdominal pain (WPP 30.8% [95%CI 27.4% - 34.3%], I²=91.6%), rash (WPP 28.4% [95%CI 25.3% - 31.7%), I²=98.8%) and diarrhoea [WPP 9.4% [95%CI 6.0% - 13.1%), I²=80.7%].

Returning travellers were more likely to be asymptomatic with a WPP of 44.63% (95%CI 38.57 - 50.75%), whilst migrant groups commonly presented with abdominal pain (WPP 42.4% (95%CI 35.1% - 47.9%) and diarrhoea (WPP 65.3% [95%CI 25.2 - 96.8%]). Rashes were a frequent complaint in those diagnosed with S. stercolaris in the armed forces (WPP 75.3% [95%CI 70.2% - 80.1%]).

The most common diagnostic modality in reported cases was Strongyloides serology (51.8%), followed by stool culture (30.8%). A small number were diagnosed with the use of ELISA (9.1%). When analysing laboratory findings, the average eosinophil count was 1.75x10⁹/L (standard deviation ±1.24x10⁹/L).

Of the 478 patients followed up, 255 were treated successfully (30.8%). There were only 4 reports of hyper-infection.

Conclusion

Our meta-analyses illustrates that a third of patients with S. stercoralis infectionin the UK were asymptomatic, whilst commonly reported symptoms may include non-specific abdominal pain, diarrhoea, and a rash. Given these non-specific presentations, clinicians should have a low threshold in screening migrant groups and returning travellers for S. stercoralis – particularly if there are plans for immunosuppressive therapy.