Prevention of blood-borne HIV transmission using a decentralized approach in Shaba, Zaire

Assessment of rapid diagnostic tests and fourth-generation Enzyme-Linked Immunosorbent Assays in the screening of Human Immunodeficiency and Hepatitis B virus infections among first-time blood donors in Libreville (Gabon)

BACKGROUND

Blood transfusion is a pathway for the transmission of blood-borne pathogens such as human immunodeficiency virus (HIV) and hepatitis B virus (HBV) from donors to recipients in most countries in sub-Saharan Africa, including Gabon. The study aimed to compare the performance of four rapid diagnostic tests (RDTs: Alere DETERMINE, BIOSYNEX Exacto Pro HIV, MEDIFF HIV 1&2, and BIOSYNEX IMMUNOQUICK HBsAg) with results of 4th-generation immunoenzymatic assays COBAS 6000 e601 and EVOLIS BioRad for the detection of HIV and hepatitis B surface antigen (HBsAg) in blood donors in Libreville, Gabon.

METHODS

Reactive and nonreactive blood samples for HIV and HBsAg were selected using fourth-generation ELISA COBAS 6000 e601 and EVOLIS BioRad. The sensitivities of RDTs were calculated using Epi Info version 6.04dfr (CDC, Atlanta, USA).

RESULTS

Sensitivities for the detection of HIV in blood donors were 90.9% for Alere DETERMINE, 81.8% for BIOSYNEX Exacto Pro HIV, and 81.8% for MEDIFF HIV 1&2 Serum/sang Total Cassette compared with COBAS 6000 e601. The sensitivity of Alere DETERMINE compared to the semi-automated ELISA Bio-Rad for HIV detection was 65.6%. The sensitivity of BIOSYNEX IMMUNOQUICK HBsAg compared to ELISA tests for the detection of HBsAg was 78.0%. The specificity of all RDTs for the detection of HIV and HBsAg was 100%.

CONCLUSION

Alere DETERMINE HIV-1/2, MEDIFF HIV 1&2 Serum/sang Total Cassette, BIOSYNEX Exacto Pro HIV, and BIOSYNEX IMMUNOQUICK HBsAg are not recommended for determining whether donors qualify to donate blood because of their low sensitivity for the detection of HIV antibodies and HBsAg in blood donors in Gabon.

Should we neglect or nurture replacement blood donors in sub-Saharan Africa?

Lack of blood is common in SSA but quantification of the overall shortfall is hampered by a lack of evidence-based targets for blood collection. Despite recommendations that all blood donors should be voluntary and non-remunerated, replacement donors are common throughout sub-Saharan Africa (SSA). Voluntary donors are generally recruited through centralised systems whereas replacement donors are recruited by families and donate through hospitals. Blood from a centralised service is more expensive than from a hospital-based service due to the higher costs of donor recruitment, quality assurance processes and the maintenance of distribution networks. Information about the contribution of replacement donors to the blood supply is scanty and inconsistent but it is likely that they currently provide over half of the blood in SSA. WHO's guidelines for transfusion services deal exclusively with voluntary donors and neglect the substantial contribution made by replacement donors. Examples of how the supply and quality of blood from the replacement donors can be improved have been published but need to be evaluated and disseminated. Political will and open-mindedness to innovative ways to improve supply and safety of blood from all types of donors are essential to promote more evidence-based approaches to blood transfusion practice in low-income countries.

Health economics of blood transfusion safety--focus on sub-Saharan Africa

BACKGROUND AND OBJECTIVES

Health economics provides a standardised methodology for valid comparisons of interventions in different fields of health care. This review discusses the health economic evaluations of strategies to enhance blood product safety in sub-Saharan Africa.

METHODS

We reviewed health economic methodology with special reference to cost-effectiveness analysis. We searched the literature for cost-effectiveness in blood product safety in sub-Saharan Africa.

RESULT

HIV-antibody screening in different settings in sub-Saharan Africa showed health gains and saved costs. Except for adding HIV-p24 screening, adding other tests such as nucleic acid amplification testing (NAT) to HIV-antibody screening displayed incremental cost-effectiveness ratios greater than the WHO/World Bank specified threshold for cost-effectiveness. The addition of HIV-p24 in combination with HCV antibody/antigen screening and multiplex (HBV, HCV and HIV) NAT in pools of 24 may also be cost-effective options for Ghana.

CONCLUSIONS

From a health economic viewpoint, HIV-antibody screening should always be implemented in sub-Saharan Africa. The addition of HIV-p24 antigen screening, in combination with HCV antibody/antigen screening and multiplex (HBV, HCV and HIV) NAT in pools of 24 may be feasible options for Ghana. Suggestions for future health economic evaluations of blood transfusion safety interventions in sub-Saharan Africa are: mis-transfusion, laboratory quality and donor management.

Reducing replacement donors in Sub-Saharan Africa: challenges and affordability

In 1975, the World Health Assembly recommended that blood for transfusion should come from voluntary, non-remunerated donors; yet, in Africa, 75-80% of blood for transfusion still comes from hospital-based replacement donors. Although comprehensive economic data are scarce, evidence indicates that blood from voluntary donors recruited and screened at centralized transfusion centres, costs four to eight times as much as blood from a hospital-based, replacement donor system. Donor recruitment, quality assurance systems and distribution mechanisms in the centralized system are major reasons for the cost difference. There are concerns about the sustainability of centralized voluntary donor systems and their compatibility with the levels of health care that exist in many poor countries yet burdening patients' families with the responsibility of finding replacement blood donors will exacerbate poverty and reduce the safety of the blood supply. There are measures that can be introduced into hospital-based systems to improve safe blood supply in Africa but their effectiveness in different contexts needs to be evaluated.

Blood transfusion rate in Congolese patients with sickle cell anemia

OBJECTIVE

The main objective of this study was to evaluate the rate of blood transfusion in African Sickle Cell Patients and the risks related to the use of total blood.

METHODS

186 sickle cell patients (95 males and 91 females) aged 0-21 years were regularly followed over a 3 years period in Katanga province, DR Congo. Indications for blood transfusion were mainly based on clinical criteria and Hb level (less than 5g% ml or a drop of 2g% under the steady state value). All the subjects, who were transfused, wer screened for hepatitis B surface antigen (HBs Ag) and Human Immune deficit Virus (HIV).

RESULTS

Of 186 patients, 150 (80.6%) were transfused and the average blood transfusion requirement was 0.4 units per patient-year. According to the age of first transfusion, 75.3% (113/150) of them were transfused before the 6th year of life; but the frequency of transfusions seemed to decline in children aged more than 13 years. The risk of HIV infection from blood transfusion was estimated at 1 per 37.1 units or 26 per 1000 blood units. The hepatitis B surface antigen was detected in 15 cases (10%) and HIV serology was positive in 17 patients (11.3%).

CONCLUSION

Because of the complications related to blood transfusions in Africa, efforts are needed in order to reduce the frequency of transfusions, by preventive measures (early diagnosis, malarial and penicillin-prophylaxis) and to use more rational indications.

Multiplexed immunoassays by flow cytometry for diagnosis and surveillance of infectious diseases in resource-poor settings

An accurate, rapid and cost-effective diagnosis is the cornerstone of efficient clinical and epidemiological management of infections. Here we discuss the relevance of an emerging technology, multiplexed immunoassays read by flow cytometry, for the diagnosis of infectious diseases. In these assays, multiple fluorescent microspheres, conjugated to different antigens or antibodies, constitute the solid phase for detecting antibodies or antigens in biological samples. These assays seem to be more sensitive than traditional immunoassays, have a high throughput capacity, and provide a wide analytical dynamic range. Additionally, they have multiplexing ability-ie, they are capable of measuring multiple antibodies or antigens simultaneously. We discuss four different areas where this technology could make an impact in resource-poor settings: (i) infections causing rash and fever in children; (ii) sero-epidemiological studies on vaccine-preventable diseases; (iii) management of genital ulcers and vaginal discharge; and (iv) screening of infections in blood banking. We predict a widespread use for a new breed of small, affordable, practical flow cytometers as field instruments for replacing ELISA and RIA tests, which will also be capable of doing cellular immunological tests such as CD4+ T-cell enumeration and Plasmodium falciparum detection in whole blood.

HIV and blood transfusion in sub-Saharan Africa

Blood transfusion services were poorly developed until the mid 1980s in most of sub-Saharan Africa, and were unable to provide adequate supplies of blood with acceptable safety. The pandemic of HIV was recognized seroepidemiologically from 1985 onwards. Blood transfusion was contributing from 10 to 15% to transmission in Africa. Groups at highest risk are children with malaria and anaemia, women with pregnancy-related haemorrhage or anaemia, victims of trauma and subjects with sickle-cell disease. Haemophiliacs are not a major risk group in comparison. Blood transfusion services have undoubtedly benefitted from the international, national and regional responses to the AIDS epidemic. Organizational structures have been established. There have been concerted moves to recruit voluntary unremunerated blood donors, selected from population groups with low seroprevalence. Serological screening for HIV, hepatitis viruses and syphilis has been introduced or strengthened. Standards for blood group serology, blood storage and handling have been improved. Guidelines for the appropriate use of blood have been formulated and adopted. There have been many training and retraining programmes. Much remains to be completed, however, using national and international resources, before the blood supply reaches acceptable standards of safety and is adequate in remote as well as in central areas of Africa.

[Sickle cell anemia in the south of Zaire. Study of two series of 251 and 340 patients followed-up 1988-1992]

BACKGROUND

This work concerns 591 sickle cell disease patients followed by the same paediatrics team in south Zaire.

POPULATION

Two series of homozygous sickle cell patients were studied: 1) 251 in-patients hospitalized in Kolwezi during the period 1988-1989, and 2) 340 out-patients examined in Lubumbashi during the period 1990-1992.

RESULTS

In the first series, a high proportion of children aged 3-5 years (30.7%) and 6-12 years (54%) was observed in comparison with a control group of patients hospitalized for anemia at the same time. The symptoms of the disease occurred during the first year of life in 80% of the children: hand-foot syndrome and/or anemia. Tooth decay was observed as soon as the age of 3 years with a high frequency (62%) as compared with the control group. Epistaxis, sometimes very important, was observed in 39.5% and 52% of the cases in children respectively aged 6-12 years and up to 13. A splenomegaly was noted during a longer period than in the control group, suggesting associated causing factors different from malaria, perhaps alpha thalassemia. The high frequency of viral contaminations due to transfusion is illustrated by the seropositivity prevalences of HIV (11.5%), HBV (10%) and in the children in Lubumbashi.

CONCLUSION

The main interest of these series of children is to point out the clinical specificities of a cohort genetically homogenous, offering the opportunity of defining basis of inter-individual variability of sickle cell disease.

HIV seroprevalence in healthy blood donors in northeastern Zaire

Despite high seroprevalence rates in some parts of Africa, there is notable variation in prevalence between population subgroups. To document changes and trends in HIV seroprevalence in northeastern Zaire, 1989 to 1992 blood donor data were reviewed. Overall, 2453 donors were tested with seropositivity varying from 2.8% in 1989 to 6.9% in 1992. The increase in seropositivity was significant for men (2.5 to 5.8%, P = 0.017) and for people residing in rural areas (2.0 to 6.1%, P = 0.0008) but not for women (5.4 to 8.6%, P = 0.15) nor for urban individuals (10.5 to 8.6%, P = 0.55). These findings suggest that: 1) HIV infection is spreading in previously less-affected population subgroups rather than increasing widely in the entire population, 2) the HIV epidemic could be reaching a plateau or endemic phase in northeastern Zaire, and, 3) continued blood donor screening and wise transfusion practices are needed.