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|Year : 2004 | Volume
| Issue : 1 | Page : 64--65
HIV-1 infection in a patient of acute lymphocytic leukaemia missed by HIV-spot and HIV-scan rapid tests
S Singh, V Kumari, N Singh
Department of Laboratory Medicine, All India Institute of Medical Sciences, New Delhi - 110 029, India
Department of Laboratory Medicine, All India Institute of Medical Sciences, New Delhi - 110 029
A case of HIV-1 infection, presumably acquired through unsafe blood transfusion in an acute lymphocytic leukemia (ALL) patient, is reported here in whom the two rapid HIV antibody detection kits (HIV-spot and HIV-Scan) failed to diagnose the infection while the sample was strongly positive in microwell ELISA (detect- HIV) on the same day and was confirmed by western blot assay (NEW LAV BLOT-1). However, repeat sample after 15 days was found positive in all the tests. Though the rapid tests are preferred over microwell ELISA because of ease of performance and rapid availability of results, this report confirms low sensitivity of the two rapid tests. This suboptimal sensitivity, particularly in cases of early seroconversion, therefore, must be borne in mind for screening the blood and organ donors under strategy-I.
|How to cite this article:|
Singh S, Kumari V, Singh N. HIV-1 infection in a patient of acute lymphocytic leukaemia missed by HIV-spot and HIV-scan rapid tests.Indian J Med Microbiol 2004;22:64-65
|How to cite this URL:|
Singh S, Kumari V, Singh N. HIV-1 infection in a patient of acute lymphocytic leukaemia missed by HIV-spot and HIV-scan rapid tests. Indian J Med Microbiol [serial online] 2004 [cited 2019 Jul 17 ];22:64-65
Available from: http://www.ijmm.org/text.asp?2004/22/1/64/8067
Since the original description of the acquired immunodeficiency syndrome (AIDS) in 1981 in the USA and its causative agent, the Human Immunodeficiency Virus (HIV) in 1983, this infection has been recognized worldwide. The disease has now been reported from more than 173 countries and cases are increasing unabated accounting for 5.8 million new cases in 1998. Of the people living with AIDS/HIV, 89% were in Sub-Saharan Africa and Asia, particularly in Thailand and India. By the end of year 2000 the same trend has continued infecting 36.1 million, of whom 20 million have died. Though India is classified as a low endemic country for HIV infection, the cumulative number of persons living with HIV infection is highest with a calculated 3.86 million cases of HIV infection.
The laboratory diagnosis of HIV infection in a suspected person is made by detecting antibodies against the virus and the most commonly used antibody detection methods are enzyme linked immunosorbent assay (ELISA) or rapid/spot tests. The reactive sera are retested by another ELISA or a rapid test. The discordant results are further tested by supplemental tests like western blot, line immunoassay (LIA) or recombinant immunoblot assay (RIBA).
According to the WHO/UNAIDS guidelines, the first or screening test should have highest possible sensitivity while second and third tests should carry highest specificity. Accordingly the first test of choice is microwell ELISA and the spot/rapid tests should supplement the ELISA results, as the rapid and confirmatory tests are less sensitive. However, recently various agencies have advocated screening of samples using rapid/simple tests based on easy and rapid result and post test counselling to the patient, thus avoiding waiting time for test results. Another purported advantage is cost effectiveness if small number of sera are to be tested. In India, recently, the National AIDS Control Organisation (NACO) has authorised blood banks to replace ELISA with rapid/simple tests.
We came across an interesting case of recent HIV infection in an adult male patient of acute lymphocytic leukaemia (ALL). The patient contracted HIV infection most likely through blood transfusion, as several blood transfusions were given to him outside, before he was referred to the All India Institute of Medical Sciences (AIIMS), the latest blood transfusion being three months ago. At AIIMS, as a routine practice, the serum was screened for transfusion transmitted blood borne infections, the Hepatitis B, C and HIV. On microwell enzyme linked immunosorbent assay (ELISA) for HIV (Detect-HIV,TM Biochem-Immunocompromised System Inc., Montreal, Canada), the serum was found strongly reactive (OD ratio 8.1). We retested the same sample on the same day with HIV-Spot (Genelabs Diagnostics Pvt. Ltd., Singapore). The test was negative, repeatedly. We further used another simple/rapid test- HIVSCANTM (E-Y Laboratories Inc., USA). This test gave indeterminate results as 6 out of 10 technicians, who did not know about the status of result, failed to see any spot, while only 4 could see a faint dot. Due to these discordant results, we carried out a western blot test using NEW LAV BLOT-I (Sanofi-Biorad,® France). The western blot results showed clear bands of gp160, gp120, P68, P55, P52, gp41, P40, P34, P25 and P24. According to the manufacturer's guidelines the sera showing 2 envelop + gag + pol bands are considered positive. Hence, the serum was reported positive for HIV-1 infection. The repeat sample, however, after 15 days was positive in all the test kits including the two rapid tests.
WHO/UNAIDS recommend rapid tests for small laboratories which perform less than 90 tests per day., These recommendations are based on the fact that rapid test kits are easy to perform, they are rapid and thus the patient need not come on another day to collect the report. In addition, these tests do not require electricity and equipment like ELISA reader and washer., However, our case is an important example of missing an infectious patient in the early seroconversion stage by rapid tests. This report also emphasizes that if, as per WHO/UNAIDS guidelines, these tests are used as the only screening test on hard-to-reach populations like CSWs, IVD users, and now in some blood banks too, the consequences could be undesirable.
Several workers have reported suboptimal sensitivity of rapid tests ranging from 94.5% to 98.2%.,, Kuun et al evaluated five rapid tests and two of these tests were significantly less sensitive on the seroconversion panels and three tests failed to detect at least one of the positive samples in the low titer panel. They found that higher antibody levels are required to develop a visible spot on the membrane while standard ELISA tests detected all the low titer HIV antibody positive samples. The authors concluded that a rapid screening test should, therefore, be adopted only after careful consideration of the effect of a possible lack of sensitivity on the safety of the blood supply.
The present case indicates that missing even single infectious patient will tantamount to life of a blood or organ recipient, or several others who share injection devices with such patients. In this patient we have no information about the method of the donor blood samples screening, prior to transfusion to this patient. Nevertheless, the lack of sensitivity of these two reputed rapid tests is documented here with the help of several other test methods and western blot assay. Therefore, we would like to recommend that all HIV diagnostic tests be evaluated in each geographical region, particularly if they are adopted as screening test for surveillance and blood safety. The rapid tests, despite their advantages over the conventional microwell ELISA, can not match the sensitivity of the latter and WHO recommends ELISA as the most appropriate test for larger laboratories.
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