Filariasis and transfusion‐associated risk: a literature review

Abstract

Background and objectives Filariae are parasitic worms that include the pathogens Loa loa, Onchocerca volvulus, Wuchereria bancrofti, Brugia spp. and Mansonella spp. which are endemic in parts of Africa, Asia, Asia‐Pacific, South and Central America. Filariae have a wide clinical spectrum spanning asymptomatic infection to chronic debilitating disease including blindness and lymphedema. Despite successful eradication programmes, filarial infections remain an important –albeit neglected – source of morbidity. We sought to characterize the risk of transfusion transmission of microfilaria with a view to guide mitigation practices in both endemic and non‐endemic countries. Materials and methods A scoping review of scientific publications as well as grey literature was carried out by a group of domain experts in microbiology, transfusion medicine and infectious diseases, representing the parasite subgroup of the International Society of Blood Transfusion. Results Cases of transfusion‐transmitted filariasis are rare and confined to case reports of variable quality. Transfusion‐associated adverse events related to microfilariae are confined to isolated reports of transfusion reactions. Serious outcomes have not been reported. No known strategies have been implemented, specifically, to mitigate transfusion‐transmitted filariasis yet routine blood donor screening for other transfusion‐transmissible infections (e.g. hepatitis B, malaria) may indirectly defer donors with microfilaremia in endemic areas. Conclusion Rare examples of transfusion‐transmitted filariasis, without serious clinical effect, suggest that filariasis poses low transfusion risk. Dedicated mitigation strategies against filarial transfusion transmission are not recommended. Given endemicity in low‐resource regions, priority should be on the control of filariasis with public health measures.

Climate change and parasitic risk to the blood supply

“…Filariasis, which refers to infection with any one of a variety of parasitic filarial worms is a neglected tropical disease and has been previously reviewed by our group. We concluded that filariasis poses low transfusion risk and did not recommend strategies against filarial transfusion transmission 27 …”

“…We concluded that filariasis poses low transfusion risk and did not recommend strategies against filarial transfusion transmission. 27…”

Prevalence of Haemoparasites among Blood Donors Attending the Regional Hospital Center of Franceville (Southern Gabon)

“…Both infections are transmitted by arthropods, Chrysops for the former and Culicoides for the latter, and are endemic in 10-33 sub-Saharan Africa countries including Gabon [17,19]. Cases of transfusion-transmitted filariasis are rare and were reported in Chad, India, and the United States with no serious adverse events [20].…”

“…In addition, all neighborhoods in the study area are surrounded by vegetation, and thus constitute potential reservoirs of Chrysops or Culicoides. The presence of microfilaria in donors' blood is of matter of concern as transfusion-transmitted filariasis could cause allergic reactions in blood recipients [20].…”

An Overview of the Management of Mansonellosis

“…18,19 At present, the WHO does not provide explicit guidance on how blood stocks contaminated with microfilariae should be treated. 20 In a recent scoping expert panel review, it was concluded that it was unnecessary to screen for or mitigate against microfilariae contamination; however, not all experts share this view, and it appears some blood banks adopt the position that transfusion of blood contaminated in any way should be avoided. 17,[20][21][22]…”