A review of the role of infections in the aetiology of haemolysis in patients with sickle cell diseases: pathogenesis, management, and prevention

Background: Sickle cell disease (SCD) is associated with chronic haemolysis, immuno-suppression and susceptibility to infections, which may trigger infection-associated haemolysis (IAH). SCD patients are vulnerable to anaemic effect of IAH due to vicious interaction between pre-existing 'inherited' chronic haemolysis and 'acquired' IAH. IAH in SCD manifests as febrile haemolytic crisis with clinical and laboratory features of severe anaemia or pancytopenia. Clinico-pathological perspectives of IAH in SCD are fragmented. This review presents a comprehensive but concise overview of pathogenesis, management and prevention of IAH in SCD. Methodology and results: Online literature search using search terms such as 'sickle cell disease, viral, bacterial, parasitic, fungal, infections, hyperhaemolytic crisis, haemophagocytic syndrome, severe anaemia, pancytopenia' in various combinations was done on PubMed/Medline, Google, Google-Scholar and Bing. Overall, 112 relevant publications were retrieved, which included 109 peer reviewed journal articles, 2 World Health Organization (WHO) technical reports, and 1 edited text book. A range of bacterial (Bartonella spp, Mycoplasma spp., Mycobacterium avium complex), viral (Dengue, SARS-CoV-2, Parvovirus-B19, Cytomegalovirus, Epstein-Barr virus), parasitic (Plasmodium spp., Babesia spp.), and fungal (Histoplasma spp.) infections were associated with IAH in SCD. There are two broad types of IAH in patients with SCD; infection associated extra-medullary haemolysis (IAEMH) and infection associated intra-medullary haemolysis (IAIMH). While IAEMH is associated with severe anaemia due to intravascular haemolysis caused by red cell invasion, oxidative injury, auto-antibodies, and/or pathogen-haem interaction, IAIMH is associated with haemophagocytic tri-lineage destruction of haematopoietic precursors in the bone marrow. Conclusion: Various microbial pathogens have been associated with IAH in SCD. SCD patients with fever, severe anaemia or pancytopenia should be investigated for early diagnosis and prompt treatment of IAH, which is a lifethreatening haematological emergency for which transfusion therapy alone may not suffice. Prompt and sustainable termination of IAH may require therapeutic combination of transfusion, anti-microbial chemotherapy, and immune modulation therapy. SCD patients should also receive counselling on hygiene, barrier protection against vectors, routine chemoprophylaxis for locally endemic diseases, and immunization for vaccine-preventable infections as a long-term preventive strategy against IAH.

Deferral patterns of voluntary blood donors at the National Blood Transfusion Service, North East zonal centre, Maiduguri

Appropriate donor selection in an important step in ensuring safe supply of blood and blood products. In this study deferral patterns of voluntary non-renumerated blood donors were determined at the North-Eastern Zonal Centre of the National Blood Transfusion service. The study was conducted between April 2007 and April 2009; and it involved the administration of a structured questionnaire. A total of 4032 voluntary blood donors were recruited; seven hundred and thirteen (17.7) were temporarily deferred. The commonest reasons for deferral were low haemoglobin; self-deferral; high blood pressure; low weight and high risk behaviour. Other reasons are use of certain medications; low blood pressure and failed venopuncture. Gender analysis showed that more females were deferred for low haemoglobin and more males were self-deferred. Following donor recall; 146 of the 173 donors temporarily deferred came back to donate. These consisted of 113 deferral due to low haemoglobin; 30 self-deferred and 3 induced in risky behaviour. Effective education or counseling; the old tradition of giving haematinics and good dietary advice to those with low haemaglobin values; improved the safety and availability of blood and blood products. Donors who are self-deferred and those involved in high risk bahviour should never be persuaded to donate blood. There is also the need for a review of operational guidelines with regards the uniform acceptable cut-off point of 12.5g/dl haemoglobin value for males and females

The Prevalence and Clinical Significance of Du Phenotype in Rhesus D Negative Pregnant Women in Maiduguri; Nigeria

To determine the prevalence and clinical significance of Du phenotype in Rhesus D negative pregnant women in Maiduguri; Nigeria; samples from 800 pregnant women who attended routine antenatal clinic from January 2004 to March 2005 were analyzed prospectively with respect to their ABO and Rhesus Blood group system. All Rhesus D negative women had elaborate indirect antiglobulin test to detect the presence of Du phenotype. The commonest ABO blood group system was group O. The prevalence's of Rhesus D positive and Rhesus D negative was 90.3