title: Immunochromatographic antigen testing alone is sufficient to identify asymptomatic refugees at risk of severe malaria presenting to a single health service in Victoria.
abstract: Current screening guidelines for malaria in new refugees include a combination of thick and thin film examination and immunochromatographic antigen test (ICT). However, as the prevalence of malaria in our population has decreased due to changing refugee demographics, we sought to determine if an ICT alone can reliably exclude malaria in our asymptomatic refugee population.A retrospective analysis was conducted of all investigations for malaria performed from 1 August 2011 to 31 July 2013, including thick and thin blood film examination, BinaxNOW ICT, and external morphological and polymerase chain reaction (PCR) validation where applicable.Malaria was diagnosed in 45 of 1248 (3.6%) patients investigated, all of whom were symptomatic and the majority (71.1%) returned travellers. All 599 asymptomatic refugees screened were negative. Overall, 42 of 45 malaria cases were detected by the ICT; sensitivity 93.3% (95% CI 80.7-98.3%) and negative predictive value (NPV) 99.8% (99.2-99.9%). All 21 cases of Plasmodium falciparum and 20 of 22 cases of Plasmodium vivax were detected, giving a sensitivity of 100% (80.8-100%) and 90.9% (69.4-98.4%) respectively. Too few cases of Plasmodium malariae and no cases of Plasmodium ovale or Plasmodium knowlesi were diagnosed for adequate assessment to be carried out.These data suggest that full malaria screening in all asymptomatic refugees with the combination of thick and thin blood films and rapid antigen test may not be warranted. Alternative screening approaches should be considered, including the use of ICT alone, or limiting screening of asymptomatic refugees to only those originating from countries with high incidence of malaria.
authors.affiliation: 1Department of Clinical Haematology 2Department of Infectious Diseases, Monash Medical Centre, Clayton 3Refugee Health Service, Monash Health, Vic, Australia.
authors.forename: Pasquale L
authors.initials: PL
authors.lastname: Fedele
authors.forename: Michael
authors.initials: M
authors.lastname: Wheeler
authors.forename: Christopher
authors.initials: C
authors.lastname: Lemoh
authors.forename: Sanjeev
authors.initials: S
authors.lastname: Chunilal
mesh_terms: D000328:Adult; D000953:Antigens, Protozoan / Q000097:blood*; D058070:Asymptomatic Diseases; D002846:Chromatography, Affinity / Q000379:methods*; D005260:Female; D006801:Humans; D008288:Malaria / Q000175:diagnosis* / Q000453:epidemiology / Q000469:parasitology; D008297:Male; D008403:Mass Screening; D010963:Plasmodium falciparum / Q000276:immunology / Q000302:isolation & purification*; D010965:Plasmodium malariae / Q000276:immunology / Q000302:isolation & purification*; D010966:Plasmodium vivax / Q000276:immunology / Q000302:isolation & purification*; D016133:Polymerase Chain Reaction; D015995:Prevalence; D012036:Refugees; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014195:Travel; D014739:Victoria / Q000453:epidemiology
chemical_list: D000953:Antigens, Protozoan