Maintaining a safe and adequate blood supply during Zika virus outbreaks: interim guidance
Overview
These guidelines have been developed in recognition that infection with Zika virus may present a risk to blood safety, and in consideration of the declaration on 1 February 2016 by the WHO Director-General of a Public Health Emergency of International Concern with regard to clusters of microcephaly and other neurological disorders, potentially associated with Zika virus. Currently there is limited knowledge of Zika virus biology and lack of definitive evidence of a link between infection and potential complications. These guidelines will be regularly reviewed and updated as new information becomes available.
Zika virus is a mosquito-borne flavivirus, related to dengue. It is transmitted to humans through the bite of an infected mosquito from the Aedes genus. This mosquito also transmits dengue, chikungunya and yellow fever viruses [23].
Zika virus infection is followed by an incubation period prior to the development of clinical symptoms, which occur in only a minority of infected individuals. Asymptomatic infections are common, as described for other flaviviral infections such as dengue and West Nile fevers. It has been reported that only one in five individuals infected with Zika virus develops symptoms [4, 13]. The symptoms of Zika virus infection are similar to those of other arboviruses such as dengue, and include fever, skin rashes, conjunctivitis, muscle and joint pain, malaise, and headache. These symptoms are usually mild and typically last for 2–7 days. The incubation period is likely to be a few days to a week [4, 24], with some publications suggesting that it may be as long as twelve days [9]. Zika virus RNA has been detected in blood, urine, and saliva during the acute phase of the disease, and in seminal fluid after acute illness; infectious virus was detected in semen more than two, and possibly up to ten weeks, after recovery from clinical symptoms of Zika virus infection, and probable cases of sexual transmission have been described [7, 8, 14, 15].
A link between Zika virus infection during pregnancy and microcephaly in neonates is suspected and currently being investigated for causal association [12, 21]. An association of Zika virus with Guillain-Barré syndrome (GBS) and other autoimmune neurological complications was suspected during a 2013–2014 outbreak in French Polynesia and remains under investigation [6, 16].
During the Zika virus outbreak in French Polynesia between November 2013 and February 2014, a total of 1,505 healthy blood donors were tested by nucleic acid amplification technology (NAT) -based assays, with 42 (2.8 %) confirmed positive for Zika virus RNA. Blood donors positive for Zika virus RNA were contacted retrospectively to investigate the occurrence of ‘Zika feverlike syndrome’ (rash and/or conjunctivitis and/or arthralgia) after their blood donation. Of the 42 donors that tested positive, 11 declared that they had a Zika fever-like syndrome from 3–10 days after they gave blood. No transmission of Zika virus through transfusion was documented in this study [3, 13]. However, transmission of related flaviviruses (dengue and West Nile viruses) by blood transfusion has been documented [2, 18, 22]. Recently two probable cases of Zika virus transmission by blood transfusion have been reported from Campinas, Brazil [19].
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