Latent infection in HIV-positive refugees and other immigrants in Australia

To the Editor: Refugees and other immigrants may carry latent infections not endemic to Australia. Immunocompromised people, including those living with HIV, are at particular risk of reactivation of such infections.1 Screening for schistosomiasis and strongyloidiasis in patients with HIV is not currently recommended by Australian guidelines2 or the United States guidelines that they reference;3 however, it is recommended by those of the United Kingdom.4

We sought to determine the prevalence of latent tuberculosis (TB), Schistosoma spp. and Strongyloides stercoralis in a cohort of people living with HIV attending a tertiary care hospital in Melbourne. The study received approval from our research ethics committee. Between 1 January 1990 and 6 March 2014, a total of 500 patients were under the care of the HIV clinic. These patients were included in a retrospective analysis of data extracted from existing pathology and administrative databases.

Mean age at presentation was 38 years, median length of time attending the clinic was 24.5 months (range, 1–289 months), and 383 patients (77%) were male. Two hundred and twenty patients (44%) were born outside Australia in over 60 different countries. Fifty-eight patients (12%) originated from low-income countries, 106 (21%) from middle-income countries, and 324 (65%) from high-income countries, including Australia.

All patients were included to assess screening for TB in accordance with existing guidelines, which currently recommend screening at diagnosis.2,3 Only patients from areas endemic for schistosomiasis (> 10% prevalence)5 were included in the data extraction for schistosomiasis screening. Similarly, only patients from areas endemic for strongyloidiasis (> 20% or unknown prevalence)6 were included in the data extraction for strongyloidiasis screening.

We also performed a prospective analysis of previously unscreened patients attending the clinic from 7 March to 29 August 2014.

Serological testing comprised QuantiFERON-TB Gold (Cellestis) (Mantoux testing for some patients before 2004), Schistosoma IgG indirect haemagglutination assay (ELITech), and Strongyloides IgG enzyme immunoassay (DRG Diagnostics).

In the retrospective audit, five of 58 patients who had been screened for schistosomiasis returned positive serology results, indicating past or current infection. In the prospective sample, one of 22 patients was found to have a past or current Schistosoma infection that was previously undiagnosed despite the patient originating from an endemic country.

In our retrospective analysis, seven of 83 patients who had been screened for strongyloidiasis returned positive serology results, indicating past or current infection. In the prospective phase, one of 20 patients was found to have a past or current S. stercoralis infection that was previously undiagnosed despite the patient having come from an endemic country.

In the retrospective audit, 10 patients were diagnosed with active TB and were excluded from further analysis. TB screening was recorded in 257 of 490 patients (52%); of these, 24 (9%) were positive and 11 (4%) had indeterminate results. In the prospective sample, two of 19 patients not previously screened for TB returned positive results. Both of these patients were born in high-risk countries.

Our results suggest that screening for TB, strongyloidiasis and schistosomiasis should be a part of primary care for HIV-infected patients originating from areas endemic for these infections.