Dear Sir,
filariasis is the name of a group of tropical diseases caused by several species of nematode parasites and their larvae. Elephantiasis is the major cause of disability as a complication of filariasis. Filariasis can be classified as an important blood infection.
As for other blood infections, transfusion-related transmission is possible. Filariasis due to blood transfusion is a new topic in tropical medicine. However, changing population demographics, increased travel and immigration, and the greater occurrence of certain asymptomatic infections in blood donors all lead to the need for new policies to maintain transfusion safety in non-endemic areas. The incidence of filarial parasites in donated blood is an interesting topic, even though there are only a few reports on this subject. A study on blood parasites in donors in Nigeria, revealed the following parasite prevalences: microfilaria of Loa loa (1.3%); Dipetalonema perstans (15.6%); both Loa loa and D. perstans (0.2%), Plasmodium falciparum (3.3%), Plasmodium malariae (1.0%) and a mixture of Plasmodium falciparum and Plasmodium malariae (0.2%)1. According to another study by Akinboye and Ogunrinade, 11.3% of donors in Nigeria had blood parasites; 7.8% had Plasmodium falciparum with parasitaemias from 0.03–0.2%, and 3.5% had Loa loa microfilaraemia2. In the experience of the author in Thailand, no filarial parasites have been detected in the blood centre of a tertiary hospital for at least 10 years. However, there are sporadic cases in rural, endemic areas.
At present, the recommendation to screen for filarial parasites in donated blood is limited to only some countries. There have been sporadic reported cases of transfusional filariasis. Choudhury et al. studied the association of post-transfusion reactions and filarial infections in an endemic area of India and reported that filarial antibody was detected in 55.3% of blood donors but microfilaria were detected in 8.5%3. They concluded that transfusion-associated filarial infection might be a probable cause of transfusion-associated morbidity in endemic areas and allergic reactions due to this transfusion-associated filarial infection were important3. Imported cases have also been described. Weller et al. first reported on tourism-acquired Mansonella ozzardi microfilaraemia in a blood donor and this was the first warning of possible problematic transfusional filariasis in a non-endemic area4. For example, transfusional Mansonella perstans microfilariasis was reported from Milan by Bregani et al5. Combined diethylcarbamazine plus mebendazole was recommended for treatment.
In conclusion, in endemic areas, all donor blood should be screened for malarial and filarial parasites.
References
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