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HIV testing among injecting drug users in Glasgow
Journal of Infection (1993) 26, 27-3I
HIV testing a m o n g injecting d r u g users in G l a s g o w Robert Covell,* Edward Follett~g, Isobel Coote~ Michael Bloor$ Andrew Finlay,t Martin Frischer, II David Goldberg,!l Stephen Green,[I Sally Haw* and Neil McKeganey*
* University of Glasgow,t University of Ulster, Northern Ireland, t M R C Medical Sociology Unit, Glasgow, I[ Communicable Diseases (Scotland) Unit, Glasgow and ~ Hepatitis/HIV Reference Laboratory, Ruchill Hospital, Glasgow, U.K. Accepted for publication 27 April 1992 Summary The use of saliva rather than blood for epidemiological studies of HIV prevalence, especially among injecting drug users, has several practical advantages. In a crosssectional, behavioural and prevalence study among drug users in Glasgow during 199o, salivary samples were therefore obtained by the use of salivettes. Such samples were requested for anonymous anti-HIV testing from 498 persons in locations varying from residential rehabilitation centres to the open streets. Of this number, 35 refused to give a sample, resulting in a compliance rate of 93 %. Of the 463 salivettes received by the laboratory, eight were found to be dry. Of the remaining 455 specimens, eight were found to be positive for HIV-I antibody by means of an IgG antibody capture ELISA, so giving a prevalence rate of 1.8 %. The results of testing saliva and blood spot samples collected at the same time on filter paper from 98 persons for HIV-I antibody were ioo % concordant. The study confirms the experience of others that specimens of saliva are easy to collect under variable conditions by non-medical staff and demonstrates that the salivette can provide an HIV antibody test result the same as that obtained from a blood spot. The prevalence of HIV antibody determined in this study is similar to that of other studies taking place in the city during the same period of time.
Introduction Since testing for antibodies to the h u m a n i m m u n o d e f i c i e n c y virus (HIV) was first introduced, tests have been p e r f o r m e d on serum from blood specimens usually obtained by venepuncture. Over the past 4 years, however, there have been reports from England, 1-3 the U . S . A . , 4'5 F i n l a n d 6 and Canada 7 of the use of saliva as an alternative to blood for H I V a n t i b o d y testing. Favourable c o m m e n t s have been m a d e on the ease of collection, reduction in the risk of accidental needle-stick injuries and reduced anxiety for patients. A particular application of the use of saliva (as opposed to blood) for H I V a n t i b o d y testing is in the investigation of injecting drug users (IDU), especially in connection with epidemiological studies. Compliance in such studies m a y be considerably impaired by the unwillingness of I D U s t o allow access to their veins. 7 In any event, v e n e p u n c t u r e in such persons is often difficult owing to prior damage Address correspondence and requests for off-prints to: Dr E. A. Follett, Hepatitis/HIV Reference Laboratory, Ruchill Hospital, Bilsland Drive~ Glasgow (320 9NB, Scotland~ U.K. oi63-4453/93/OlOOe7+o5 $08.00/0
© I993 The British Society for the Study of Infection
28
R. C O V E L L E T A L .
by multiple self-inflicted assaults on veins often with unsterile needles. A recent study in L o n d o n , conducted in the relatively well-controlled circumstances of needle/syringe exchange, ~ showed that salivary testing was acceptable to drug users. D u r i n g the first year of a 3-year annual cross-sectional study of I D U s in Glasgow, 8 salivary specimens were tested for H I V antibody by means of I g G antibody capture E L I S A ( G A C E L I S A ) . 1 Materials and methods
In order to obtain a sample population of drug users from a wide area of Greater Glasgow, recruitment was from multiple sites in the city. Fifteen of these were ' O u t of D r u g T r e a t m e n t ' sites. T h e y included needle and syringe exchange schemes as well as chemists' shops and hospital accident and emergency departments, while some persons came directly from the streets. Thirteen others were ' I n D r u g T r e a t m e n t ' s i t e s - - c o m m u n i t y based and residential drug projects together with a hospital inpatient detoxification unit. This sampling strategy was designed so as to produce as wide a representation of I D U s as was possible. At the beginning of each interview, which incorporated questions on drug taking and sexual behaviour relevant to the risk of acquiring H I V infection, respondents were told that they would be asked to provide a sample of saliva for anonymous H I V testing. At the end of the interview, the final question of which concerned the respondent's known H I V status, he or she was invited to provide a sample of saliva. T h e samples were provided by gently chewing for 3o-45 s on the cotton wool pledgelet from a salivette (Sarstedt Ltd). This was then replaced in its plastic container. T h e container was later delivered by the interviewer, together with the completed interview questionnaire, to a researcher who linked the two with a study n u m b e r u n b e k n o w n to the interviewer. T h e r e b y confidentiality could be preserved. On its receipt at the virus laboratory, each container was centrifuged at 4ooo r p m for Io min in order to collect the saliva for testing. Most of t h e m yielded i - 2 ml saliva. Testing was performed by an I g G antibody capture assay ( G A C E L I S A ) developed at the Virus Reference Laboratory, Central Public Health Laboratory, L o n d o n . Materials for this were supplied to us by Drs Mortimer and Parry. Eluates from dried blood spots were prepared as previously described2 For testing of saliva, 5o #1 saliva from a salivette was used and for eluates from blood spots IO #1 in 90 #1 diluent. T h e G A C E L I S A test is now commercially available from Wellcome Diagnostics, Beckenham, U . K . Because of the low concentration of antibody present in saliva and blood spot eluates, a modified Western blot system which allows lower final dilutions of small volumes was used for confirmatory testing exactly as described previously for dried blood spot eluates. ° Western blots of saliva samples were run with 25 #1 salivette fluid and 5o #1 buffer. Criteria of positivity were as prevously defined i.e. bands had to be present representing reactivity against one or more of the gag and pol proteins and one of the env proteins. Where possible, in the hospital setting, blood samples for H I V antibody testing were also requested. Blood was taken by finger-prick using the autolet
H I V testing among injecting drug users
29
Table I Saliva specimens : results of H I V antibody tests H I V antibody tests negative H I V antibody tests repeatedly reactive in G A C E L I S A and confirmed by Western blot
447 8
455
Table II Comparison of blood spot and salivette samples Anti-HIV status
Number of samples tested
Blood spot mean OD
Salivette mean OD
Negative Positive
94 4
0"209 2"842
o' 169 3 'o 18
OD, Optical density.
(Owen M u m f o r d Ltd) and then absorbed on filter paper. Dried samples were tested in the laboratory for H I V antibody by G A C E L I S A and positive tests confirmed by Western blot. Altogether, 98 blood samples were matched with saliva samples taken from the same respondents. Results Compliance
Of the 498 respondents from w h o m a saliva test was requested, 35 (7%) refused, giving a compliance rate of 93 %. Tests for antibody to HIV
T h e salivette has proved easy to administer, to transport and to handle both in and out of the laboratory. Of the 463 salivettes sent to the laboratory, however, 8 (I'7 %) were found to be dry, possibly due to the interviewer's failure in instructing the correct collection technique. T h e finger-prick m e t h o d for collecting blood spot samples on filter paper provided adequate quantities of blood both for G A C E L I S A and for confirmatory testing when required. Of the 455 specimens of saliva tested for H I V antibody, nine were found to be initially reactive in G A C E L I S A and eight repeatedly reactive. All eight of the latter were confirmed as being H I V positive by Western blot, thereby indicating a total of 447 specimens which were negative (Table I). Of all the specimens of saliva tested, 98 were matched with blood spot specimens taken from the same persons. Of the 98, 94 were H I V antibody negative and four positive (Table II). T h e results of G A C E L I S A on the saliva and blood spot samples were Ioo % concordant. In addition, there was little difference between the optical densities provided by the G A C E L I S A test from either source (Table II).
3°
R. COVELL E T A L . Discussion
T h e use of a capture i m m u n o a s s a y ( G A C E L I S A ) for detecting H I V antibody in samples of saliva collected from I D U s recruited from multiple locations has been very satisfactory. T h e main advantages of using saliva rather than b l o o d are as follows: specimens can be taken b y interviewers w h o are not clinically qualified; locations where sterile conditions are difficult to achieve m a y be u s e d ; risk of infection from H I V or hepatitis viruses introduced b y needlestick accidents is avoided. T h e authors believe the compliance rate of 93 % to be satisfactory where H I V testing is voluntary. T h i s m a y be i m p r o v e d in s u b s e q u e n t years of the study. O n e potential disadvantage of using saliva as o p p o s e d to b l o o d taken b y v e n e p u n c t u r e might have been the collection of samples insufficient for testing. Eight (2 %) of the salivary swabs collected were reported as being totally dry. All other salivettes sent to the laboratory contained ample saliva for p r i m a r y and confirmatory testing w h e n necessary. N o n e of the b l o o d samples collected on filter paper was insufficient for testing or confirmation. Training interviewers in the collection of saliva for the next phase of the study will be intensified in an attempt to reduce the n u m b e r of dry swabs. Salivette samples have p r o v e d to be highly acceptable in the laboratory w h e n used in conjunction with the G A C E L I S A test. T h e preparation of a suitable sample is simple (centrifugation), the volume obtained is sufficient for all screening and confirmatory tests and the test results are very clean, with few non-repeatable reactives or false-positives. O u r comparison with b l o o d spots suggests that the salivette can provide as good a result as can be obtained from a b l o o d spot. An accurate comparison of the sensitivity of the systems, however, w o u l d require serial samples of b o t h types from a seroconverting patient. T h e extremely low H I V prevalence of I-8 % among Glasgow I D U s f o u n d in this study is similar to that recorded for I99O b y the H I V laboratory surveillance p r o g r a m m e of the C o m m u n i c a b l e Diseases (Scotland) U n i t (personal communication). T h i s also accords with the findings of the allScottish study based on unlinked a n o n y m o u s H I V testing of n e w b o r n babies in I99o, 9 wherein not a single positive H I V test was recorded for babies b o r n in Glasgow. (This work is funded by the U.K. Medical Research Council, Grant no. SPG 8913894 with additional support from the World Health Organization. We thank Drs J. Parry and P. Mortimer for providing the GACELISA Test and are grateful to Eleanor Gallacher for her administrative and organizational support.) References
I. Parry JV, Perry KR, Mortimer PP. Sensitive assays for viral antibodies in saliva: an alternative to tests on serum. Lancet I987, ii: 72-75. 2. Johnson AM, Parry JV, Best SJ, Smith AM, de Silva M, Mortimer PP. HIV surveillance by testing saliva. A I D S I988; 2: 369-37I. 3. Hart GJ. Carvell, AL, Woodward N, Johnson AM, Williams P, Parry JV. Evaluation of needle exchange in Central London: behaviour and anti-HIV status over one year. A I D S T989; 3: 261-265.
H I V testing among injecting drug users
31
4. Archibald DW, Zon L, Groopman JE. McLome MF, Essex M. Antibodies to human Tlymphotropic virus type I I I (HTLV iii) in saliva of acquired immunodeficiency syndrome (AIDS) patients and in persons at risk for AIDS. Blood 1986; 67:831-834 . 5. Shoeman RL, Pottatbil R, Metroka C. Antibodies to HIV in saliva. N Engl J Med I989; 320: 1145-1146. 6. Holstrom P, Syrjanen S, Larrie P, Valle SL, Simi J. HIV antibodies in whole saliva detected by ELISA and Western Blot assays, ff 2~led Virol 199o; 3o: 245-248. 7. Major CJ, Reid SE, Coates R A et al. Comparison of saliva and blood for human immunodeficiency virus. Prevalence testing. Infect Dis 1991 ; 163: 699-702. 8. Haw S, Frischer M, Covell R et al. HIV infection and risk behaviour among injecting drug users in Glasgow. Answer (AIDS News Supplement, CDS Weekly Report), Communicable Diseases (Scotland) Unit, Ruchill Hospital, Glasgow 91/31, 1-4, 1991. 9. Tappin DM, Girdwood RWA, Follett EAC, Kennedy R, Brown AJ, Cockbum F. Prevalence of maternal HIV infection in Scotland based on unlinked anonymous testing of newborn babies. Lancet 1991; 337: 1565-1567.
HIV testing a m o n g injecting d r u g users in G l a s g o w Robert Covell,* Edward Follett~g, Isobel Coote~ Michael Bloor$ Andrew Finlay,t Martin Frischer, II David Goldberg,!l Stephen Green,[I Sally Haw* and Neil McKeganey*
* University of Glasgow,t University of Ulster, Northern Ireland, t M R C Medical Sociology Unit, Glasgow, I[ Communicable Diseases (Scotland) Unit, Glasgow and ~ Hepatitis/HIV Reference Laboratory, Ruchill Hospital, Glasgow, U.K. Accepted for publication 27 April 1992 Summary The use of saliva rather than blood for epidemiological studies of HIV prevalence, especially among injecting drug users, has several practical advantages. In a crosssectional, behavioural and prevalence study among drug users in Glasgow during 199o, salivary samples were therefore obtained by the use of salivettes. Such samples were requested for anonymous anti-HIV testing from 498 persons in locations varying from residential rehabilitation centres to the open streets. Of this number, 35 refused to give a sample, resulting in a compliance rate of 93 %. Of the 463 salivettes received by the laboratory, eight were found to be dry. Of the remaining 455 specimens, eight were found to be positive for HIV-I antibody by means of an IgG antibody capture ELISA, so giving a prevalence rate of 1.8 %. The results of testing saliva and blood spot samples collected at the same time on filter paper from 98 persons for HIV-I antibody were ioo % concordant. The study confirms the experience of others that specimens of saliva are easy to collect under variable conditions by non-medical staff and demonstrates that the salivette can provide an HIV antibody test result the same as that obtained from a blood spot. The prevalence of HIV antibody determined in this study is similar to that of other studies taking place in the city during the same period of time.
Introduction Since testing for antibodies to the h u m a n i m m u n o d e f i c i e n c y virus (HIV) was first introduced, tests have been p e r f o r m e d on serum from blood specimens usually obtained by venepuncture. Over the past 4 years, however, there have been reports from England, 1-3 the U . S . A . , 4'5 F i n l a n d 6 and Canada 7 of the use of saliva as an alternative to blood for H I V a n t i b o d y testing. Favourable c o m m e n t s have been m a d e on the ease of collection, reduction in the risk of accidental needle-stick injuries and reduced anxiety for patients. A particular application of the use of saliva (as opposed to blood) for H I V a n t i b o d y testing is in the investigation of injecting drug users (IDU), especially in connection with epidemiological studies. Compliance in such studies m a y be considerably impaired by the unwillingness of I D U s t o allow access to their veins. 7 In any event, v e n e p u n c t u r e in such persons is often difficult owing to prior damage Address correspondence and requests for off-prints to: Dr E. A. Follett, Hepatitis/HIV Reference Laboratory, Ruchill Hospital, Bilsland Drive~ Glasgow (320 9NB, Scotland~ U.K. oi63-4453/93/OlOOe7+o5 $08.00/0
© I993 The British Society for the Study of Infection
28
R. C O V E L L E T A L .
by multiple self-inflicted assaults on veins often with unsterile needles. A recent study in L o n d o n , conducted in the relatively well-controlled circumstances of needle/syringe exchange, ~ showed that salivary testing was acceptable to drug users. D u r i n g the first year of a 3-year annual cross-sectional study of I D U s in Glasgow, 8 salivary specimens were tested for H I V antibody by means of I g G antibody capture E L I S A ( G A C E L I S A ) . 1 Materials and methods
In order to obtain a sample population of drug users from a wide area of Greater Glasgow, recruitment was from multiple sites in the city. Fifteen of these were ' O u t of D r u g T r e a t m e n t ' sites. T h e y included needle and syringe exchange schemes as well as chemists' shops and hospital accident and emergency departments, while some persons came directly from the streets. Thirteen others were ' I n D r u g T r e a t m e n t ' s i t e s - - c o m m u n i t y based and residential drug projects together with a hospital inpatient detoxification unit. This sampling strategy was designed so as to produce as wide a representation of I D U s as was possible. At the beginning of each interview, which incorporated questions on drug taking and sexual behaviour relevant to the risk of acquiring H I V infection, respondents were told that they would be asked to provide a sample of saliva for anonymous H I V testing. At the end of the interview, the final question of which concerned the respondent's known H I V status, he or she was invited to provide a sample of saliva. T h e samples were provided by gently chewing for 3o-45 s on the cotton wool pledgelet from a salivette (Sarstedt Ltd). This was then replaced in its plastic container. T h e container was later delivered by the interviewer, together with the completed interview questionnaire, to a researcher who linked the two with a study n u m b e r u n b e k n o w n to the interviewer. T h e r e b y confidentiality could be preserved. On its receipt at the virus laboratory, each container was centrifuged at 4ooo r p m for Io min in order to collect the saliva for testing. Most of t h e m yielded i - 2 ml saliva. Testing was performed by an I g G antibody capture assay ( G A C E L I S A ) developed at the Virus Reference Laboratory, Central Public Health Laboratory, L o n d o n . Materials for this were supplied to us by Drs Mortimer and Parry. Eluates from dried blood spots were prepared as previously described2 For testing of saliva, 5o #1 saliva from a salivette was used and for eluates from blood spots IO #1 in 90 #1 diluent. T h e G A C E L I S A test is now commercially available from Wellcome Diagnostics, Beckenham, U . K . Because of the low concentration of antibody present in saliva and blood spot eluates, a modified Western blot system which allows lower final dilutions of small volumes was used for confirmatory testing exactly as described previously for dried blood spot eluates. ° Western blots of saliva samples were run with 25 #1 salivette fluid and 5o #1 buffer. Criteria of positivity were as prevously defined i.e. bands had to be present representing reactivity against one or more of the gag and pol proteins and one of the env proteins. Where possible, in the hospital setting, blood samples for H I V antibody testing were also requested. Blood was taken by finger-prick using the autolet
H I V testing among injecting drug users
29
Table I Saliva specimens : results of H I V antibody tests H I V antibody tests negative H I V antibody tests repeatedly reactive in G A C E L I S A and confirmed by Western blot
447 8
455
Table II Comparison of blood spot and salivette samples Anti-HIV status
Number of samples tested
Blood spot mean OD
Salivette mean OD
Negative Positive
94 4
0"209 2"842
o' 169 3 'o 18
OD, Optical density.
(Owen M u m f o r d Ltd) and then absorbed on filter paper. Dried samples were tested in the laboratory for H I V antibody by G A C E L I S A and positive tests confirmed by Western blot. Altogether, 98 blood samples were matched with saliva samples taken from the same respondents. Results Compliance
Of the 498 respondents from w h o m a saliva test was requested, 35 (7%) refused, giving a compliance rate of 93 %. Tests for antibody to HIV
T h e salivette has proved easy to administer, to transport and to handle both in and out of the laboratory. Of the 463 salivettes sent to the laboratory, however, 8 (I'7 %) were found to be dry, possibly due to the interviewer's failure in instructing the correct collection technique. T h e finger-prick m e t h o d for collecting blood spot samples on filter paper provided adequate quantities of blood both for G A C E L I S A and for confirmatory testing when required. Of the 455 specimens of saliva tested for H I V antibody, nine were found to be initially reactive in G A C E L I S A and eight repeatedly reactive. All eight of the latter were confirmed as being H I V positive by Western blot, thereby indicating a total of 447 specimens which were negative (Table I). Of all the specimens of saliva tested, 98 were matched with blood spot specimens taken from the same persons. Of the 98, 94 were H I V antibody negative and four positive (Table II). T h e results of G A C E L I S A on the saliva and blood spot samples were Ioo % concordant. In addition, there was little difference between the optical densities provided by the G A C E L I S A test from either source (Table II).
3°
R. COVELL E T A L . Discussion
T h e use of a capture i m m u n o a s s a y ( G A C E L I S A ) for detecting H I V antibody in samples of saliva collected from I D U s recruited from multiple locations has been very satisfactory. T h e main advantages of using saliva rather than b l o o d are as follows: specimens can be taken b y interviewers w h o are not clinically qualified; locations where sterile conditions are difficult to achieve m a y be u s e d ; risk of infection from H I V or hepatitis viruses introduced b y needlestick accidents is avoided. T h e authors believe the compliance rate of 93 % to be satisfactory where H I V testing is voluntary. T h i s m a y be i m p r o v e d in s u b s e q u e n t years of the study. O n e potential disadvantage of using saliva as o p p o s e d to b l o o d taken b y v e n e p u n c t u r e might have been the collection of samples insufficient for testing. Eight (2 %) of the salivary swabs collected were reported as being totally dry. All other salivettes sent to the laboratory contained ample saliva for p r i m a r y and confirmatory testing w h e n necessary. N o n e of the b l o o d samples collected on filter paper was insufficient for testing or confirmation. Training interviewers in the collection of saliva for the next phase of the study will be intensified in an attempt to reduce the n u m b e r of dry swabs. Salivette samples have p r o v e d to be highly acceptable in the laboratory w h e n used in conjunction with the G A C E L I S A test. T h e preparation of a suitable sample is simple (centrifugation), the volume obtained is sufficient for all screening and confirmatory tests and the test results are very clean, with few non-repeatable reactives or false-positives. O u r comparison with b l o o d spots suggests that the salivette can provide as good a result as can be obtained from a b l o o d spot. An accurate comparison of the sensitivity of the systems, however, w o u l d require serial samples of b o t h types from a seroconverting patient. T h e extremely low H I V prevalence of I-8 % among Glasgow I D U s f o u n d in this study is similar to that recorded for I99O b y the H I V laboratory surveillance p r o g r a m m e of the C o m m u n i c a b l e Diseases (Scotland) U n i t (personal communication). T h i s also accords with the findings of the allScottish study based on unlinked a n o n y m o u s H I V testing of n e w b o r n babies in I99o, 9 wherein not a single positive H I V test was recorded for babies b o r n in Glasgow. (This work is funded by the U.K. Medical Research Council, Grant no. SPG 8913894 with additional support from the World Health Organization. We thank Drs J. Parry and P. Mortimer for providing the GACELISA Test and are grateful to Eleanor Gallacher for her administrative and organizational support.) References
I. Parry JV, Perry KR, Mortimer PP. Sensitive assays for viral antibodies in saliva: an alternative to tests on serum. Lancet I987, ii: 72-75. 2. Johnson AM, Parry JV, Best SJ, Smith AM, de Silva M, Mortimer PP. HIV surveillance by testing saliva. A I D S I988; 2: 369-37I. 3. Hart GJ. Carvell, AL, Woodward N, Johnson AM, Williams P, Parry JV. Evaluation of needle exchange in Central London: behaviour and anti-HIV status over one year. A I D S T989; 3: 261-265.
H I V testing among injecting drug users
31
4. Archibald DW, Zon L, Groopman JE. McLome MF, Essex M. Antibodies to human Tlymphotropic virus type I I I (HTLV iii) in saliva of acquired immunodeficiency syndrome (AIDS) patients and in persons at risk for AIDS. Blood 1986; 67:831-834 . 5. Shoeman RL, Pottatbil R, Metroka C. Antibodies to HIV in saliva. N Engl J Med I989; 320: 1145-1146. 6. Holstrom P, Syrjanen S, Larrie P, Valle SL, Simi J. HIV antibodies in whole saliva detected by ELISA and Western Blot assays, ff 2~led Virol 199o; 3o: 245-248. 7. Major CJ, Reid SE, Coates R A et al. Comparison of saliva and blood for human immunodeficiency virus. Prevalence testing. Infect Dis 1991 ; 163: 699-702. 8. Haw S, Frischer M, Covell R et al. HIV infection and risk behaviour among injecting drug users in Glasgow. Answer (AIDS News Supplement, CDS Weekly Report), Communicable Diseases (Scotland) Unit, Ruchill Hospital, Glasgow 91/31, 1-4, 1991. 9. Tappin DM, Girdwood RWA, Follett EAC, Kennedy R, Brown AJ, Cockbum F. Prevalence of maternal HIV infection in Scotland based on unlinked anonymous testing of newborn babies. Lancet 1991; 337: 1565-1567.