Infectious Disease Markers in Blood Donors

Abstract

Background

The infectious disease markers for which blood donors are screened include anti-human immunodeficiency virus (HIV), hepatitis B surface antigen (HBsAg), anti-hepatitis C virus (HCV), rapid plasma reagin (RPR) card test for syphilis and malarial parasites.

Methods

A total of 6751 donors were screened over three years to assess the prevalence of infectious disease markers. Screening for anti-HIV I and II, HBsAg and anti-HCV was carried out by enzyme linked immunosorbent assay (ELISA). Syphilis was tested using RPR card test. Malarial parasite was tested by detection of genus specific plasmodium lactate dehydrogenase.

Result

The overall seropositivity for anti-HIV I and II was nine (0.13%), for HBsAg 67 (0.99%), for anti-HCV 13 (0.19%) and for syphilis 42 (0.62%). No sample showed malarial parasites. There was no significant difference (p>0.05) in the seropositivity of various markers between voluntary and replacement donors. There was a significant decline (p<0.05) in the prevalence of seropositivity for HCV and syphilis, but not for HIV and HBsAg over the three year period of the study.

Conclusion

The prevalence of infectious disease markers was similar to that reported by other studies. However, no significant difference was seen in the marker positivity in voluntary and replacement donors, which is at variance from other studies.

Introduction

Blood is a scarce and life saving resource, however blood transfusion can be a source for transmitting life threatening infections if screening is not carried out properly [1]. The prevalence of anti-human immunodeficiency virus (HIV), hepatitis B surface antigen (HBsAg), anti- hepatitis C virus (HCV) and syphilis positivity in Indian blood donors is 0.084-3.87% [2, 3, 4, 5], 0.66-12% [2, 3, 4], 0.5-1.5% [2, 3, 4, 6, 7, 8] and 0.85-3% [2, 3, 4] respectively. The present study was done to estimate the prevalence of infectious disease markers in the donor population of the blood bank of a tertiary care hospital of the armed forces.

Material and Methods

A total of 6751 units of blood was collected from voluntary and replacement donors over a three year period. Voluntary donors had donated blood either in the blood bank or in camps organised by mobile teams. Replacement donors had come to the centre to donate blood to replace that required by patients and were either relatives or friends of the patient. Professional donors were excluded. Samples were screened by enzyme linked immunosorbent assay (ELISA) kits from J Mitra & Co Ltd for anti-HIV I and II, HBsAg and anti-HCV. Third generation anti-HCV ELISA test kits utilizing a combination of antigens with the sequence of both HCV structural and non-structural antigens i.e. Core, E1, E2, NS3, NS4 and NS5 were used. Validity of ELISA tests was assessed by means of acceptance criteria laid down by the manufacturer for the absorbance of reagent blank as well mean absorbance of positive and negative controls present with the test kits. Cut off value for reporting positive results was calculated as per manufacturer's directions. Known positive and negative controls were randomly used as external controls. Screening for syphilis was carried out using rapid plasma reagin (RPR) card test from Tulip Diagnostics Pvt Ltd. Malaria screening was done by a rapid test kit for detection of malaria genus specific plasmodium lactate dehydrogenase released from parasitized red cells utilizing the principle of immunochromatography (Zephyr Biomedicals). Reactive samples were retested before being labelled as seropositive. Seropositive blood units were discarded.

Results

A total of 6751 donors were screened over a period of three years, of which 5783(85.67%) were replacement and 968(14.33%) voluntary donors. Percentage of HIV seropositivity was 0.12% in 2003, 0.17% in 2004 and 0.10 in 2005, with an overall seropositivity of 0.13%. The prevalence of seropositivity in voluntary and replacement donors is shown in Table 1. The difference in prevalence in these two groups is not statistically significant (p>0.05). There is no significant change in the prevalence of HIV positivity over the three year period (Table 2).

Table 1.

HIV positivity in voluntary and replacement donors

HIV status	Voluntary	Replacement	Total
Positive	01	08	09
Negative	967	5775	6742
Total	968	5783	6751

χ² = 0.04; p value = 0.84 (non significant)

Table 2.

HIV prevalence trend

Year	HIV positive	HIV negative	Total
2003	03	2411	2414
2004	04	2299	2303
2005	02	2032	2034
Total	09	6742	6751

χ² = 0.48; p value = 0.79 (non significant)

HBsAg seropositivity ranged from 0.79% in 2003, 1.13% in 2004 and 1.08% in 2005, the overall figure being 0.99%. There is no significant difference in the prevalence of HBsAg positivity in voluntary and replacement donors (Table 3). There was no significant change in the prevalence of HBsAg over the study period (Table 4).

Table 3.

HbsAg positivity in voluntary and replacement donors

HBsAg status	Voluntary	Replacement	Total
Positive	15	52	67
Negative	953	5731	6684
Total	968	5783	6751

χ² = 2.94; p value = 0.09 (non significant)

Table 4.

HbsAg prevalence trend

Year	HbsAg positive	HBsAg negative	Total
2003	19	2395	2414
2004	26	2277	2303
2005	22	2012	2034
Total	67	6684	6751

χ² = 1.64; p value – 0.44 (non significant)

HCV seropositivity fell from 0.41% in 2003 to 0.05% in 2005 with an overall positivity of 0.19%. The difference in prevalence of anti-HCV positivity in voluntary and replacement donors is not significant (Table 5). There was a significant decline (p<0.05) in the prevalence of anti-HCV positivity over the three year period (Table 6).

Table 5.

HCV positivity in voluntary and replacement donors

HCV status	Voluntary	Replacement	Total
Positive	02	11	13
Negative	966	5772	6738
Total	968	5783	6751

χ² = 0.08; p value = 0.77 (non significant)

Table 6.

HCV prevalence trend

Year	HCV positive	HCV negative	Total
2003	10	2404	2414
2004	02	2301	2303
2005	01	2033	2034
Total	13	6738	6751

χ² = 9.96; p value 0.008 (significant)

Seropositivity for syphilis showed a downward trend from 1.33% in 2003 to 0.15% in 2005, the overall figure being 0.62%. The difference in prevalence of syphilis positivity in voluntary and replacement donors is not significant (Table 7). The decline in the positivity for syphilis over the three year period was highly significant (p<0.001) (Table 8). No sample showed malarial parasites on blood smear examination.

Table 7.

Rapid plasma reagin (RPR) positivity in voluntary and replacement donors

RPR status	Voluntary	Replacement	Total
Positive	09	33	42
Negative	959	5750	6709
Total	968	5783	6751

χ² =1.20; p value = 0.27 (non significant)

Table 8.

Syphilis (RPR positivity) prevalence trend

Year	RPR positive	RPR negative	Total
2003	32	2382	2414
2004	07	2296	2303
2005	03	2031	2034
Total	42	6709	6751

χ² = 30.5; p value = 0.00000024 (significant)

Discussion

Replacement donors (85.67%) constituted the majority of blood donors in our study, a finding similar to other studies [3, 4].

The overall prevalence of HIV seropositivity (0.13%) is lower than that of other studies [3, 4, 5], except for a seropositivity rate of 0.084% reported by Gupta N et al [2]. There was no significant difference in the prevalence between voluntary and replacement donors, unlike other studies [2, 3, 4], which showed a lower prevalence of HIV positivity in voluntary donors. There was no significant change in prevalence of HIV seropositivity over the three year period of the study.

The prevalence of HBsAg seropositivity (0.99%) is similar to that reported by other studies [2, 3, 4]. There was no significant difference in the prevalence rate amongst voluntary and replacement donors which is at variance from other studies [2, 3, 4], which showed a higher seropositivity in replacement as compared to voluntary donors. There was no significant change in the prevalence of HBsAg positivity in the study period.

Anti-HCV positivity (0.19%) was lower than that reported by other studies [2, 3, 4, 6, 7, 8], without any significant difference in voluntary and replacement donors. This was at variance from other studies [2, 3, 4, 6, 7, 8], where anti-HCV positivity was higher in replacement donors as compared to voluntary donors. Anti-HCV positivity showed a significant downward trend during the study period.

Syphilis positivity (0.62%) was similar to other studies [2, 3, 4]. No significant difference in prevalence was found among voluntary as compared to replacement donors, which is at variance from other studies [2, 3, 4], which showed a higher positivity among replacement donors. The positivity for syphilis showed a significant downward trend over the study period.

To conclude, the overall prevalence of positivity for infectious disease markers among donors in this study is similar to that reported by other studies in India [2, 3, 4, 5, 6, 7, 8], except for the lower incidence of HCV positivity found in this study. This may be due to the fact that donors in a service hospital are likely to be from a better socio-economic background than the donor population of a civil hospital. The lack of any significant difference among voluntary as opposed to replacement donors could be due to the fact that both voluntary and replacement donors in the armed forces are likely to be from the same socio-economic strata. At least in the setting of the armed forces, the use of replacement donors would appear to be as safe as the use of voluntary donors. The downward trend in the prevalence of HCV and syphilis is an encouraging finding. The lower prevalence of HCV will contribute to safety of the blood supply. The lower incidence of syphilis positivity is unlikely to be of much significance as the causative organism dies within seventy two hours of storage.

Conflicts of Interest

None identified

Personal No Rank	Name in full	Appointment	Previous Unit	Present Address
	(as per Army list)	(speciality)		(with PIN)