Burden and clinical impact of 'neglected' transfusion-transmitted infections in Cameroon: A systematic review and meta-analysis

Blood supply is a public health challenge in African countries. In Cameroon, blood selection guidelines focus on four viral and bacterial pathogens (HIV, hepatitis B and C viruses, Treponema pallidum) associated with transfusion-transmitted infections (TTIs). Other pathogens, often endemic (e.g., Plasmodium spp.), are not routinely screened in blood banks and are not included in blood safety guidelines or surveillance, despite their potential for transfusion transmission.

Here, we conducted a systematic review and meta-analysis of prevalence, determinants, and clinical impact of 'neglected' pathogens, defined as pathogens not included in national blood safety guidelines (e.g., filaria, dengue virus, Toxoplasma gondii), in blood banks. Additionally, we identified the most urgent challenges and proposed actionable solutions to guide blood safety guidelines in the country.

A total of 18 studies, covering ~12,500 donations, were included, with the bulk coming from donors living in three regions (Littoral, Northwest, Centre). Plasmodium parasite (68.4%) was the major studied pathogen, even though an evident publication bias was found (p = 0.004). The other pathogens included dengue virus (5.3%), T. gondii (5.3%), and HTLV-1 (5.3%). The filarial parasite Loa loa was consistently accidentally found. Even though there is no evidence of SARS-CoV-2-associated TTIs till now, the pooled proportion of this virus was 17.7%. The pooled proportions of infection in blood donors were 16.6% for Plasmodium spp. and 0.5% for Loa loa. There is a paucity of clinical impact studies on these 'neglected' TTIs, and the available literature suggests impaired levels of immunoglobulin E and albumin. We identified urgent challenges, including awareness among healthcare providers and policymakers, diagnostic and logistical constraints, and low microbial density infections, associated with neglected pathogen-related blood safety.

We opine that providing more epidemiological evidence is crucial to address the above-mentioned challenges for guiding and guaranteeing blood safety in Cameroon.