Screening for latent tuberculosis and gastrointestinal parasite infections in Gurkha recruits: research driving policy change

O’Shea, Matthew K.; Fletcher, Tom; Tupper, David E.; Ross, Donald F.; Wilson, David E.

doi:10.1136/jramc-2014-000259

Cited by 3 publications

(3 citation statements)

References 10 publications

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“…In light of the findings presented in this study the UK Ministry of Defence has altered its policy for LTBI screening in Gurkha recruits to the use of a single T-SPOT.TB IGRA [53] . These findings are important because they have implications for LTBI diagnostic strategies in populations of migrants arriving in countries of low TB incidence from areas of high TB incidence.…”

Section: Discussionmentioning

confidence: 96%

Tuberculin Skin Testing and Treatment Modulates Interferon-Gamma Release Assay Results for Latent Tuberculosis in Migrants

et al. 2014

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BackgroundIdentifying latent tuberculosis infection (LTBI) in people migrating from TB endemic regions to low incidence countries is an important control measure. However, no prospective longitudinal comparisons between diagnostic tests used in such migrant populations are available.ObjectivesTo compare commercial interferon (IFN)-gamma release assays (IGRAs) and the tuberculin skin test (TST) for diagnosing LTBI in a migrant population, and the influence of antecedent TST and LTBI treatment on IGRA performance.Materials and MethodsThis cohort study, performed from February to September 2012, assessed longitudinal IGRA and TST responses in Nepalese military recruits recently arrived in the UK. Concomitant T-SPOT.TB, QFT-GIT and TST were performed on day 0, with IGRAs repeated 7 and 200 days later, following treatment for LTBI if necessary.Results166 Nepalese recruits were prospectively assessed. At entry, 21 individuals were positive by T-SPOT.TB and 8 individuals by QFT-GIT. There was substantial agreement between TST and T-SPOT.TB positives at baseline (71.4% agreement; κ = 0.62; 95% CI:0.44–0.79), but only moderate concordance between positive IGRAs (38.1% agreement; κ = 0.46; 95% CI:0.25–0.67). When reassessed 7 days following TST, numbers of IGRA-positive individuals changed from 8 to 23 for QFT-GIT (p = 0.0074) and from 21 to 23 for T-SPOT.TB (p = 0.87). This resulted in an increase in IGRA concordance to substantial (64.3% agreement; κ = 0.73; 95% CI:0.58-0.88). Thus, in total on day 0 and day 7 after testing, 29 out of 166 participants (17.5%) provided a positive IGRA and of these 13 were TST negative. Two hundred days after the study commenced and three months after treatment for LTBI was completed by those who were given chemoprophylaxis, 23 and 21 participants were positive by T-SPOT.TB or QFT-GIT respectively. When individual responses were examined longitudinally within this population 35% of the day 7 QFT-GIT-positive, and 19% T-SPOT.TB-positive individuals, were negative by IGRA. When the change in the levels of secreted IFN-γ was examined after chemoprophylaxis the median levels were found to have fallen dramatically by 77.3% from a pre-treatment median concentration of IFN-γ 2.73 IU/ml to a post-treatment median concentration IFN-γ 0.62 (p = 0.0002).ConclusionsThis study suggests differences in the capacity of commercially available IGRAs to identify LTBI in the absence of antecedent TST and that IGRAs, in the time periods examined, may not be the optimal tests to determine the success of chemoprophylaxis for LTBI.

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Section: Discussionmentioning

confidence: 96%

Tuberculin Skin Testing and Treatment Modulates Interferon-Gamma Release Assay Results for Latent Tuberculosis in Migrants

et al. 2014

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“…With the exception of the early work by O’Shea et al in this population [ 11 , 12 ], there are limited recent published data on GIP infection in otherwise healthy or asymptomatic migrants to the UK. A large study in 4,000 schoolchildren conducted in the 1970s found a helminth prevalence of 30–40% in those migrating from Pakistan or India, but no participants were recorded as coming from Nepal [ 33 ].…”

Section: Discussionmentioning

confidence: 99%

“…In the UK a screening programme has been in place since 2012 for personnel recruited from Nepal for the Gurkha regiments of the United Kingdom Armed Forces. Historical data had suggested high rates of helminth infection in this population [10], supported by more recent work showing a GIP prevalence of 21.7% [11,12]. In this retrospective study, we review the data from 9 years (up to 2020) of screening 2,263 members of this large, homogenous, well controlled population of healthy and economically active migrants from a GIP endemic location, namely Nepal.…”

Section: Introductionmentioning

confidence: 87%

Gastrointestinal parasite infections in Nepalese Gurkha recruits arriving in the United Kingdom from 2012–2020

Nevin,

Jones,

Tupper

et al. 2024

PLoS Negl Trop Dis

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Background Gastrointestinal parasite (GIP) infections are a major cause of global morbidity, infecting hundreds of millions of people each year and potentially leading to lifelong infection and serious complications. Few data exist on screening for GIP infections in migrants entering the UK or on the current performance of different traditional diagnostic approaches. This study aimed to describe the prevalence of GIP infections in Nepalese Gurkha recruits screened on arrival in the UK. Methodology/Principal findings We present a retrospective analysis of data from screening male adults (18–21 years) who arrived in the UK from Nepal between 2012 and 2020. Three separate faecal samples were obtained from participants at weekly intervals and processed for formalin-ethyl acetate (FEA) concentration/light microscopy and charcoal culture. Serum samples were analysed for IgG antibodies to Strongyloides stercoralis by ELISA. Results were available from 2,263 participants, of whom 463 (20.5%, 95% CI 18.8%-22.2%) had a positive diagnostic test for at least one GIP infection. A total of 525 potential infections were identified. Giardia duodenalis was most common (231/2263, 10.2%), followed by S. stercoralis (102/2263, 4.5%), and hookworm species (86/2263, 3.8%). Analysis (microscopy and culture) of the initial stool sample diagnosed only 244/427 (57.1%) faecally identified pathogens, including 41/86 (47.7%) hookworm infections. The proportion of participants infected with any GIP showed a downward trend over the study period. Log-binomial regression showed risk of infection decreasing by 6.1% year-on-year (95% CI 3.2% - 9.0%). This was driven predominantly by a fall in hookworm, S. stercoralis and Trichuris trichiura prevalence. Conclusions/Significance The level of potentially pathogenic GIP infection in young Nepalese men migrating to the UK is high (20.5%) and requires a combined diagnostic approach including serology and analysis of multiple stool samples incorporating specialised parasitological methods. Advances in molecular approaches may optimise and simplify the intensive screening strategy required.

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Chronic Strongyloides stercoralis infection in Fijian migrants to the UK

Nevin,

Melhuish,

Jones

et al. 2024

Journal of Medical Microbiology

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Introduction. Strongyloides stercoralis, the human threadworm, is a parasitic nematode with global distribution, estimated to infect over 600 million people. Chronic infection is often asymptomatic, but hyperinfection and dissemination syndromes can occur in the immunosuppressed with high case fatality rates. Whilst strongyloidiasis is endemic in Fiji, its prevalence in Fijian migrant groups in the UK is unknown. Gap Statement. No previous studies have been conducted on the prevalence of Strongyloides and other gastrointestinal parasites (GIPs) in Fijian migrants to the UK. Aim. We conducted a cross-sectional study of the prevalence of GIPs in a Fijian migrant population. Methodology. Participants completed a questionnaire on residence, travel and clinical symptoms and were asked to provide a serum sample for S. stercoralis IgG ELISA, venous blood samples for eosinophil count and a faecal sample for charcoal culture, multiplex real-time PCR (rtPCR) and microscopy after formalin-ethyl acetate concentration. Sequencing was performed on pooled Strongyloides larvae for nuclear 18S rRNA hyper-variable regions (HVRs) I and IV. Results. A total of 250 participants (94% male) with median (range) age 37 (20–51) years entered the study, 15 (1–24) years since leaving Fiji. S. stercoralis IgG ELISA was positive in 87/248 (35.1 %) and 14/74 (18.9 %) had a GIP detected in faeces. This included 7/74 (9.5 %) with Strongyloides and 5/74 (6.8 %) with hookworms. Dermatological symptoms were more common in those with Strongyloides, and eosinophilia (>0.5×109 cells per litre) was present in 55.6% of those with positive S. stercoralis IgG. rtPCR was the most sensitive faecal diagnostic test for Strongyloides and hookworms in faeces. Sequences of nuclear 18S rRNA for HVRs I and IV confirmed the presence of S. stercoralis. Conclusion. This first cross-sectional study in Fijian migrants found a high rate of chronic infection with GIPs, particularly S. stercoralis. Faecal microscopy was insensitive compared to charcoal culture, rtPCR or serology, demonstrating the importance of specialist parasitological tests when investigating people with a suspected chronic infection. Our study highlights an overlooked burden of strongyloidiasis in the UK and has implications for screening and treatment programmes in Fiji and for migrants from Fiji.

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Screening for latent tuberculosis and gastrointestinal parasite infections in Gurkha recruits: research driving policy change

Cited by 3 publications

References 10 publications

Tuberculin Skin Testing and Treatment Modulates Interferon-Gamma Release Assay Results for Latent Tuberculosis in Migrants

Tuberculin Skin Testing and Treatment Modulates Interferon-Gamma Release Assay Results for Latent Tuberculosis in Migrants

Gastrointestinal parasite infections in Nepalese Gurkha recruits arriving in the United Kingdom from 2012–2020

Chronic Strongyloides stercoralis infection in Fijian migrants to the UK

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