Implications of Dengue Outbreaks for Blood Supply, Australia

Helen M. Faddy

, Clive R. Seed, Jesse J. Fryk, Catherine A. Hyland, Scott A. Ritchie, Carmel T. Taylor, Kathryn L. Van Der Merwe, Robert L.P. Flower¹, and William J.H. McBride¹

Author affiliations: Australian Red Cross Blood Service, Kelvin Grove, Queensland, Australia (H.M. Faddy, J.J. Fryk, C.A. Hyland, K.L. Van Der Merwe, R.L.P. Flower); Australian Red Cross Blood Service, Osborne Park, Western Australia, Australia (C.R. Seed); James Cook University, Cairns, Queensland, Australia (W.J.H. McBride, S.A. Ritchie); Queensland Health, Cairns (S.A. Ritchie); Queensland Health Forensic and Scientific Services, Coopers Plains, Queensland, Australia (C.T. Taylor)

Abstract

Dengue outbreaks have increased in size and frequency in Australia, and transfusion-transmitted dengue poses a risk to transfusion safety. Using whole blood samples collected during the large 2008–2009 dengue epidemic, we estimated the risk for a dengue-infectious blood donation as ≈1 in 7,146 (range 2,218–50,021).

Dengue causes >50 million infections per year worldwide; however, the true incidence is expected to be higher given that asymptomatic infection is possible (1). Dengue virus types 1–4 (DENV-1–4) are emerging or reemerging in many regions of the world (1,2), including Australia (3). One of the largest epidemics in at least 50 years occurred in Queensland, Australia, during 2008–2009, with separate outbreaks in Cairns (and surrounding regions; DENV-2, DENV-3; 2008–2009), Innisfail (DENV-4; 2009), and Townsville (DENV-1, DENV-3; 2009), totaling >1,000 confirmed clinical cases (3).
Infection with DENVs poses a risk for transfusion safety, and 5 cases of transfusion-transmitted dengue have been reported (4,5). In addition, DENV RNA has been detected in asymptomatic blood donors from areas to which dengue is endemic (6–8). Given the absence of an approved blood screening test for dengue in Australia, managing transfusion-transmission risk focuses on identifying donors at risk for exposure and temporarily excluding them from donating fresh blood components (erythrocytes, platelets, and clinical plasma) (referred to here as dengue management strategy) (9). Plasma collection for fractionation can continue because the process of manufacturing concentrates inactivates the virus (10). This approach assists with meeting an expanding demand for intravenous Ig but may result in fresh component losses and be associated with considerable cost.
Risk to the blood supply correlates with asymptomatic donor viremia; understanding the rate of dengue subclinical infection in countries to which it is not endemic and local northern Queensland seroprevalence is necessary for assessing this risk. We examined dengue seroprevalence rates in Australian donors during this epidemic; used these data to estimate the subclinical infection rate, population prevalence, and associated transfusion-transmission risk; and estimated the economic effect of this epidemic to the Australian Red Cross Blood Service (Blood Service).