False-positive human immunodeficiency virus test and Trypanosoma cruzi infection in eastern Colombia.

To the Editor: Immunodeficiency, either human immunodeficiency virus (HIV)-positive or HIV-negative, is associated with several coinfections, including Trypanosoma cruzi. (1) However, several concerns regarding the true cause of some of these illnesses have arisen because many cross-reactions have been found with either enzymelinked immunosorbent assay (ELISA) or Western blot (WB) testing for HIV infection. (2) After previous studies performed in eastern Colombia on T cruzi infection, (3) we found a new cross-reaction for HIV that had never been described before. We wanted to report it because it might make a significant difference between life and death.

From January 1996 to December 2000, 41,059 blood samples from people considered healthy and without risk factors for HIV infection were screened for anti-HIV by HIV-1/2 enzyme immunoassay (EIA) PLUS (Abbott Laboratories, Abbott Park, IL) at the metropolitan blood bank at Bucaramanga, Colombia. Following the guidelines of the Ministry of Health of Colombia for HIV infection, the samples were tested three times; if positive, they were confirmed by HIV-WB (Genelabs, Singapur Science Park, Singapore) at the National Institutes of Health of Colombia.

When submitted to ELISA, 0.26% of samples were positive; 57.4% of those were considered HIV false-positive after the confirmatory WB tests were performed, for a final prevalence of 0.11% of HIV seropositivity for that population. More interesting was finding that 4.8% of the false-positive results were due to T cruzi infection, according to Abbott Chagas Antibody EIA (Abbott Laboratories, Sao Paulo, Brazil); this test has a sensitivity of 99% and a specificity of 98%. (3) None of the subjects studied had leishmaniasis.

Cross-reactions of HIV tests by ELISA or WB have been found in systemic lupus erythematosus, pregnancy, hepatitis, malaria, tuberculosis, miscellaneous autoimmune diseases, hematologic malignancies, as well as the amount of viral particles; disease state or some other laboratory conditions seem to play a role for producing such false-positivity. (2,4) More important were the results obtained recently from 43 blood banks in Colombia. In that study, a lack of accuracy of the serologic tests used for diagnosing transfusion-transmitted infectious disease including HIV and T cruzi was observed. (5) Thus, the HIV false-positivity due to T cruzi infection found by us makes sense and confirms those inaccurate results.

The false-positivity found in our study might have been due to the presence of some parasitic proteins such as reverse transcriptase enzyme recently found in this parasitic protazoan. (6) Therefore, a true increase in Chagas disease reactivation in people infected by HIV reported elsewhere (7) might, at present, be overestimated. The lack of viral isolation and the incomplete serologic protocols frequently used for HIV testing in many countries (8) support the contention that T cruzi and perhaps other untested germs might actually be originating a cross-reactivity on HIV testing as shown here. Finally, the small amount of HIV seropositivity found in this Colombian area contrasted with local and more frequent infectious problems present in those communities including not only Chagas disease but also malaria, tuberculosis, cholera, and dengue, among others.

References

1. Sartori AM, Neto JE, Nunes EV, Braz LM, Caiaffa-Filho HH, Oliveira Oda C Jr, et al. Trypanosoma cruzi parasitemia in chronic Chagas disease: comparison between human immunodeficiency virus (HIV)-positive and HIV-negative patients. J Infect Dis 2002;186:872-875.

2. Papadopulos-Eleopulos E, Turner VF, Papadimitriou JM, Causer D. HIV antibodies: further questions and a plea for clarification. Curr Med Res Opin 1997;13:627-634.

3. Leon-Sarmiento FE, Mendoza E, Torres-Hillera M, Pinto N, Prada J, Silva CA, et al. Trypanosoma cruzi-associated cerebrovascular disease: a case-control study in Eastern Colombia. J Neurol Sci 2004;217:61-64.

4. Alfonso H, Leon-Sarmiento FE, Brokate A, Valderrama V, Parra JE. AIDS epidemiology-based-evidence, in Leon-Sarmiento FE (ed): ViH & Los Virus de la Imaginacion Humana. Bogota, Celsus, 2001, pp 13-32.

5. Duran MB, Guzman MA. External evaluation of serology results in blood banks in Colombia. Rev Panam Salud Publica 2003;13:138-143.

6. Gonzalez CI, Thomas MC, Martin F, Alcami J, Alonso C, Lopez MC. Reverse transcriptase-like activity in Trypanosoma cruzi. Acta Trop 1997;63:117-126.

7. Sartori AM, Lopes MH, Benvenuti LA, Caramelli B, di Pietro A, Nunes EV, et al. Reactivation of Chagas' disease in a human immunodeficiency virus-infected patient leading to severe heart disease with a late positive direct microscopic examination of the blood. Am J Trop Med Hyg 1998;59:784-786.

8. Leon-Sarmiento FE, Carpintero de Jimeno M. Retrovirus, mycotoxins, immunosuppression and neurodegeneration. Rev Neurol 2002;35:562-571.

Jose E. Parra-Pineros, MSC,

Vladimir Valderrama, MD,

Pontificia Universidad Javeriana

Bogota, Colombia

Fidias E. Leon-Sarmiento, MD, PhD,

Universidad de Pamplona

Pamplona (N de Sder), Columbia

UIS-Santander University School of Medicine

Bucaramanga, Columbia

Nelson Daza, MD,

UIS-Santander University School of Medicine

Bucaramanga, Colombia

Herminia Ramirez-Diaz, BCL,

Metropolitan Blood Bank

Ramon Gonzalez Valencia University Hospital

Bucaramanga, Colombia

Marta E. Leon-Sarmiento, MSC

Neuronet-Instituto Colombiano de Neurociencias Aplicadas

Neurobiologia Humana & Neurologia Clinica y Funcional

Bucaramanga, Colombia

Jaime Bayona-Prieto, PHT, NRH

Universidad de Pamplona

Pamplona (N de Sder), Colombia

Letters to the Editor are welcomed. They may report new clinical or laboratory observations and new developments in medical care or may contain comments on recent contents of the Journal. They will be published, if found suitable, as space permits. Like other material submitted for publication, letters must be typewritten, double-spaced, and submitted in duplicate. They must not exceed two typewritten pages in length. No more than five references and one figure or table may be used. See "Information for Authors" for format of references, tables, and figures. Editing, possible abridgment, and acceptance remain the prerogative of the Editors.