新加坡有兩名個案,一開始登革熱IgM快篩陽性,但隨後RT-PCR檢驗證實感染新冠肺炎。

這兩名個案在發病早期因為登革熱快篩陽性而未被考慮感染武漢肺炎,因此未做適當的隔離與防護,不僅對病患本身,也對公共衛生造成威脅。

這兩名個案顯示新冠肺炎患者血液初期呈現登革熱偽陽性。強調迫切需要針對SARS-CoV-2快速且準確的診斷試劑。

–>最後這一句確實是原文所強調的,但是原文下這個結論比較奇怪。因為新加坡該二名病患不是因為缺乏好的、快速的診斷新冠肺炎的工具以致延誤處置。

主要關鍵在於臨床醫師診斷時除了登革熱之外也應當考慮新冠肺炎感染的可能性,並進一步安排檢驗。

雖然登革熱與新冠肺炎某些臨床表現會很相近,例如:發燒、痠痛、血小板低下、淋巴球減少等,使得疾病初期有時不易單靠臨床表現來鑑別。但是仍有二者之間可以稍加區分的症狀,包括:登革熱大多會起皮膚疹(這二名病患都沒有出疹)、新冠肺炎常有呼吸道症狀(二名病患都有明顯的呼吸道症狀)。此外,病患的TOCC資訊也是相當重要。

因此,當全球壟罩在新冠肺炎疫情下,對於登革熱流行地區,醫護人員應時刻留意該地流行病學情形。必須強調,所有的檢驗都有其極限和靈敏度的問題,仔細綜合疫情資料、病患TOCC訊息、臨床表現、檢驗結果,才能釐清感染的真相,降低公共衛生的威脅。

(財團法人國家衛生研究院 莊淑鈞博士、齊嘉鈺醫師摘要整理)

Dengue and coronavirus disease 2019 (COVID-19) are difficult to distinguish because they have shared clinical and laboratory features.12 We describe two patients in Singapore with false-positive results from rapid serological testing for dengue, who were later confirmed to have severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, the causative virus of COVID-19.

The first case is a 57-year-old man with no relevant past medical, travel, or contact history, who presented to a regional hospital on Feb 9, 2020, with 3 days of fever and cough. He had thrombocytopenia (platelet count 140 × 109/mL) and a normal chest radiograph. He was discharged after a negative rapid test for dengue NS1, IgM, and IgG (SD Bioline Dengue Duo Kit; Abbott, South Korea). He returned to a public primary health-care clinic with persistent fever, worsening thrombocytopenia (89 × 109/mL), and new onset lymphopenia (0·43 × 109/mL). A repeat dengue rapid test was positive for dengue IgM and IgG (Dengue Combo; Wells Bio, South Korea). He was referred to hospital for dengue with worsening cough and dyspnoea. A chest radiograph led to testing for SARS-CoV-2 by RT-PCR (in-house laboratory-developed test detecting the N and ORF1ab genes) from a nasopharyngeal swab, which returned positive. The original seropositive sample and additional urine and blood samples tested negative for dengue, chikungunya, and Zika viruses by RT-PCR,345 and a repeat dengue rapid test (SD Bioline) was also negative. Thus, the initial dengue seroconversion result was deemed a false positive.

The second case is a 57-year-old woman with no relevant past medical, travel, or contact history, who presented to a regional hospital on Feb 13, 2020, with fever, myalgia, a mild cough of 4 days, and 2 days of diarrhoea. She had thrombocytopenia (92 × 109/mL) and tested positive for dengue IgM (SD Bioline). She was discharged with outpatient follow up for dengue fever. She returned 2 days later with a persistent fever, worsening thrombocytopenia (65 × 109/mL), and new onset lymphopenia (0·94 × 109/mL). Liver function tests were abnormal (aspartate aminotransferase 69 U/L [reference range 10–30 U/L], alanine aminotransferase 67 U/L [reference range <55 U/L], total bilirubin 35·8 μmol/L [reference range 4·7–23·2 μmol/L]). Chest radiography was normal and she was admitted for dengue fever. She remained febrile despite normalisation of her blood counts and developed dyspnoea 3 days after admission. She was found to be positive for SARS-CoV-2 by RT-PCR from a nasopharyngeal swab. A repeat dengue test (SD Bioline) was negative and an earlier blood sample also tested negative for dengue by RT-PCR.6 The initial dengue IgM result was deemed to be a false positive.

Failing to consider COVID-19 because of a positive dengue rapid test result has serious implications not only for the patient but also for public health. Our cases highlight the importance of recognising false-positive dengue serology results (with different commercially available assays) in patients with COVID-19. We emphasise the urgent need for rapid, sensitive, and accessible diagnostic tests for SARS-CoV-2, which need to be highly accurate to protect public health.

We declare no competing interests.

Author:Gabriel Yan, Chun Kiat Lee, Lawrence T M Lam, et al.
原文連結:https://www.sciencedirect.com/science/article/pii/S1473309920301584?via%3Dihub