Brazilian spotted fever: Real-time PCR for diagnosis of fatal cases

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• 作者：Fabiana Cristina Pereira dos Santos^a ; ^{fcpereir@usp.br} ; Elvira Maria Mendes do Nascimento^a ; ^b ; Gizelda Katz^a ; Rodrigo Nogueira Angerami^c ; Silvia Colombo^a ; Eliana Rodrigues de Souza^a ; Marcelo Bahia Labruna^d ; Marcos Vinicius da Silva^e
• 关键词：Real-time PCR ; Diagnosis ; Brazilian spotted fever ; Fatal cases
• 刊名：Ticks and Tick-borne Diseases
• 出版年：2012
• 出版时间：December, 2012
• 年：2012
• 卷：3
• 期：5-6
• 页码：312-314
• 全文大小：236 K

文摘

Suspicion of Brazilian spotted fever (BSF) should occur in endemic regions upon surveillance of the acute febrile icteric hemorrhagic syndrome (AFIHS). However, limitations associated with currently available laboratory tests pose a challenge to early diagnosis, especially in fatal cases. Two real-time PCR (qPCR) protocols were evaluated to diagnose BSF in 110 fatal AFIHS cases, collected in BSF-endemic regions in 2009-2010. Of these, 24 were positive and 86 negative by indirect immunofluorescence (IFA) assay (cut-off IgG and/or IgM ¡Ý 128). DNA from these samples was used in the qPCR protocols: one to detect Rickettsia spp. (citrate synthase gene) and another to determine spotted fever group (SFG) Rickettsia species (OmpA gene). Of the 24 IFA-positive samples, 5 (21 % ) were positive for OmpA and 9 (38 % ) for citrate synthase. In the IFA-negative group (n = 86), OmpA and citrate synthase were positive in 23 (27 % ) and 27 (31 % ), respectively. These results showed that the 2 qPCR protocols were about twice as sensitive as the IFA test alone (93 % concordance). In conclusion, qPCR is a sensitive method for the diagnosis of fatal BSF cases and should be considered for routine surveillance of AFIHS in places like Brazil, where spotted fever-related lethality is high and other endemic diseases like dengue and leptospirosis can mislead diagnosis.