CORRESPONDENCE

HIV diagnosis in a mobile unit

To the Editor: I read the article on HIV diagnosis in mobile unit with great interest.¹ Van Schaik et al. concluded that 'Mobile services are accessed by a different population compared with facility-based services'.¹ I agree that the HIV diagnosis via a mobile unit can be a useful approach for early diagnosis. However, there are some problems to be kept in mind. Quality control (QC) of the HIV test should be carefully considered. There can be problems in this regard in good hospital laboratories, and there is no doubt that QC could potentially be more difficult in a mobile unit.² To optimise the usefulness of the mobile HIV screening programme, standardisation and quality management are very important.

Viroj Wiwanitkit

Wiwanitkit House
Bangkhae
Bangkok
Thailand
wviroj@yahoo.com

1. van Schaik N, Kranzer K, Wood R, Bekker LG. Earlier HIV diagnosis - are mobile services the answer? S Afr Med J 2010;100:671-674.         [ Links ]

2. Proffitt MR, Yen-Lieberman B. Laboratory diagnosis of human immunodeficiency virus infection. Infect Dis Clin North Am 1993;7(2):203-219.         [ Links ]

Van Schaik et al. reply: We agree that adequate and regular quality control of HIV test kits as well as adequate training in performing HIV tests are extremely important.

HIV tests performed at the mobile clinic, community clinic and hospital are all rapid HIV tests, performed outside a laboratory by nursing staff, and are subject to the same quality control issues.

Staff working on the mobile unit are all trained in the use of the rapid tests and our standard operating procedures. We have our own quality control programme and are part of an external quality assurance programme run by the National Health Laboratory Service (NHLS), where to date we have scored 100%. In addition we have an informal quality control method in that we see many known HIVpositive individuals who request re-testing. Any discrepant results are confirmed with laboratory HIV enzyme-linked immunosorbent assay (ELISA)/polymerase chain reaction (PCR).

HIV test kits are stored at temperatures of less than 30ºC in our offices and only enough for that day's testing are taken out on the mobile unit.

For our own quality control programme, samples from known positive and known negative individuals (confirmed by laboratory HIV ELISA testing) are run with each new batch and monthly thereafter. The control samples must give the intended response (i.e. positive or negative). The staff member who performed the quality control procedure records the results on the rapid HIV testing quality control log sheet, which then gets filed. Any control problems are immediately reported to the project manager and acted on.