兒童腸病毒感染：從腸病毒A71型到新生兒臍帶血血清流行病學研究

Abstract

研究背景 腸病毒為兒童常見感染疾病，其中腸病毒A71型、D68型、克沙奇病毒B型與伊科病毒是四種臨床上重要的非小兒麻痺腸病毒。1998年時臺灣曾發生腸病毒A71型大流行並且造成78位兒童死亡。疾病管制署因而設置許多疾病監測系統、建構腸病毒重症醫療網、推廣公共衛生教育以及制訂許多感染管制措施來防治腸病毒感染。這些疾病防治政策有效地使腸病毒A71型引起的重症與死亡人數從1998年開始到2020年之間顯著下降。在腸病毒A71型的疫情穩定控制之後，新的高風險型別包含D68型、克沙奇病毒B型與伊科病毒的威脅仍持續存在。新生兒與嬰兒感染腸病毒的臨床表現與常見感染型別與年齡較大的兒童並不相同。因此，本研究將探討新生兒臍帶血腸病毒血清流行病學研究以及嬰幼兒發燒與腸病毒感染的關聯性。

研究方法 我們自2021年01月至10月總共納入222位年齡20歲以上的產婦為受試者，接受問卷調查並且在生產時收集臍帶血進行伊科病毒11型、克沙奇病毒B3型與腸病毒D68型的中和抗體檢測。血清抗體效價≥ 1:8定義為血清抗體陽性。我們也針對2010年01月至2021年06月期間100天大嬰幼兒因發燒或腸病毒感染而至台大醫院小兒科住院的病人進行病歷回溯，蒐集人口學資料、臨床病程、檢驗結果與預後等數據。使用student t test與Mann–Whitney tests來分析連續變項。利用卡方檢定與Fisher's exact test來檢驗類別變項。多變項羅吉斯回歸分析將用於尋找與嚴重腸病毒感染有相關且具有獨立影響作用的危險因子，並計算(adjusted) odds ratio (aOR)值與95%信賴區間(95% confidence interval, 95% CI)。統計分析將使用SAS version 9.4進行，P-value小於0.05為統計顯著標準。

研究結果 新生兒臍帶血血清中和抗體研究結果顯示，伊科病毒11型、克沙奇病毒B3型與腸病毒D68型的血清陽性率分別為18% (41/222)、60% (134/232)及95% (211/222) (p<0.001). 伊科病毒11型、克沙奇病毒B3型與腸病毒D68型的幾何平均抗體效價分別為 3.3 (95% CI 2.9-3.8)、15.9 (95% 12.5-20.3) 與109.9 (95% CI 92.4-131.6)。問卷分析顯示，雖然高達98.6%的產婦了解預防腸病毒感染的措施，但在日常生活中僅73.4%會落實正確的洗手方式。病歷回溯分析在875位小嬰兒發燒的病人中，17.1%(150/875)經喉頭拭子、肛門拭子或腦脊髓液病毒培養或PCR檢驗證實有腸病毒感染。腸病毒病患有顯著較高的紅疹(p<0.001)、口腔潰瘍(p<0.001)與接觸史或群聚史(p<0.001)。實驗室檢驗部分，腸病毒病患有顯著較高的淋巴球比例(p=0.03)，腦脊髓中白血球(p<0.001)與淋巴球數(p<0.001)數也顯著較高。共有162位100天大以內的小嬰兒腸病毒感染者，感染年齡中位數為49.5天大，男嬰佔58.6%(n=95)，早產兒佔9.9%(n=16)。常見的臨床表現為發燒 (n=146，90%)、上呼吸道感染 (n=112， 69%)、中樞神經系統受侵犯 (n=69，43%)、皮疹(n=32，20%)與口腔潰瘍(n=25，15.4%)。針對所有腸病毒感染進行型別分析，NPEV是最常見的型別(n=52，32%)，其次為coxsackievirus B5 (CVB5，n=29，18%)，第三為echovirus 11(E11，n=18，11%)。侵犯中樞神經系統的腸病毒則以CVB5 (n=18，26%)、NPEV (n=16，23%)與E11 (n=11，7%)佔主要型別。多變項逐步羅吉斯迴歸分析顯示，年紀20天大以下嬰兒 (adjusted OR=10.8, 95% CI 1.6-203.2, p value=0.018)、血色素小於9 gm/dl (adjusted OR=21.1, 95% CI 2.5-179, p value=0.005)以及感染高風險型別 (adjusted OR=10.7, 95% CI 1.05-109.9, p value=0.045)為嬰幼兒感染腸病毒產生重症的主要風險因子。

結論 經胎盤所獲得的母源抗體是新生兒對抗腸病毒感染的重要免疫來源，臍帶血中伊科病毒11型的血清抗體陽性率與幾何平均效價皆顯著低於克沙奇病毒B3型與腸病毒D68型，顯示當面臨伊科病毒11型流行時，大多數新生兒是缺乏免疫力的且可能因而產生重症甚至死亡。在100天大以下的小嬰兒發燒中，腸病毒感染佔了病原的17.1%。43%小嬰兒感染腸病毒會侵犯中樞神經系統，且以非小兒麻痺腸病毒、克沙奇病毒B5型與伊科病毒11型為最常見的影響型別。未來我們仍須持續監測新生兒與小嬰兒腸病毒感染的流行病學。

Background Enterovirus infection is a common pediatric infectious disease. Enterovirus A71(EV A71), enterovirus D68 (EVD68), coxsackievirus B and echovirus are the four clinically important non-polio enterovirus. There was an EV A71 large outbreak which led to 78 children death in Taiwan in 1998. Therefore, Taiwan Centers of Disease Control set up multiple disease surveillance system, medical network of severe enterovirus infection, public health education and implemented several infection control policies to prevent enterovirus infection. These disease preventive measures control EV A71 effectively and the number of severe infection and mortality decreased significantly from 1998 to 2020. The epidemic of EV A71 was under control. However, new high risk serotypes including EVD68, coxsackievirus B and echovirus persisted and posed a threat to children health. Neonates and infants have different clinical manifestations and common serotypes of enterovirus from older children. The aim of this study is to evaluate the seroepidemiology of enterovirus in cord blood and the relationship of young infant with fever and enterovirus infection.

Materials and Methods We enrolled 222 parturient women equal to or above 20 years of age between January and October 2021. All participants underwent questionnaire investigation and we collected the cord blood to measure the neutralization antibodies against echovirus 11(E11), coxsackievirus B3 (CVB3) and EVD68. Seropositivity was defined as a serotiter ≥ 1:8. We also conducted retrospective chart review study to include infants younger than 100 days old who was admitted to National Taiwan University due to fever or enterovirus infection during January 2010 and June 2021. Demographic data, clinical course, laboratory examination and prognosis were collected and analyzed. We used student t tests and Mann–Whitney tests to examine continuous variables and analysed categorical variables by the chi-square test and Fisher’s exact test. Multivariable logistic regression analysis was used to examine the independent risk factors of severe enterovirus infection. (Adjusted) odds ratio with 95% confidence interval would also be calculated. Statistical analysis would be performed by SAS version 9.4 and P-value<0.05 was considered statistical significant.

Results The seropositive rates of cord blood were 18% (41/222), 60% (134/232) and 95% (211/222) for E11, CVB3 and EVD68, respectively (p<0.001). Geometric mean titers were 3.3 (95% CI 2.9-3.8) of E11, 15.9 (95% 12.5-20.3) of CVB3 and 109.9 (95% CI 92.4-131.6) of EVD68. Questionnaire analysis showed that although 98.6% parturient women understand the way of protection from enterovirus infection, only 73.4% would follow up the correct steps of hand washing in their daily life. Retrospective chart review enrolled 875 young infants with fever and 17.1% (150/875) were proved to have enterovirus infection via throat swab, rectal swab or cerebrospinal fluid viral isolation or PCR. Patients with enterovirus infection had significantly higher rates of skin rash(p<0.001), oral ulcer (p<0.001), and contact or cluster history (p<0.001). Lab examination showed significantly higher lymphocyte percentage (p=0.03), leukocyte(p<0.001) and lymphocyte (p<0.001) counts in the cerebrospinal fluid. 162 infants younger than 100-day old had enterovirus infection and the median age was 49.5 days old. Boys accounted for 58.6% (n=95) and prematurity accounted for 9.9% (n=16). The common symptoms of infants with enterovirus infection included fever (n=146，90%), upper respiratory tract infection (n=112，69%), central nervous system involvement (n=68，43%), skin rash (n=32，20%) and oral ulcer (n=25，15.4%). To evaluate the serotype distribution, non-polio enterovirus accounted for 32% (n=52), followed by coxsackievirus B5(n=29，18%) and E11 (n=18，11%). Coxsackievirus B5 (N=18，26%), non-polio enterovirus (n=16，23%) and E11 (n=11，7%) were the top three serotypes leading to central nervous system involvement. Multivariable logistic stepwise selection regression analysis showed that age under 20 days (adjusted OR=10.8, 95% CI 1.9-60.8, p value<0.001), hemoglobin less than 9gm/dl (adjusted OR=21.1, 95% CI 2.5-179, p value=0.005) and high risk serotypes (adjusted OR=10.7, 95% CI 1.05-109.9, p value=0.045) were the major risk factors of severe enterovirus infection.

Conclusion Transplacentally-acquired maternal antibody is an important immunity against enterovirus infection in neonates. Cord blood seropositive rate and geometric mean titer of E11 were significantly lower than CVB3 and EVD68. A large proportion of newborns are susceptible to E11 and might developed severe infection or even death when facing E11 epidemic. Enterovirus accounted 17.1% of the etiology young infant (<100 days old ) with fever. 43% young infant would have central nervous system involvement when having enterovirus infection. The common serotypes were non-polio enterovirus, coxsackievirus B5 and E11. It is imminent to monitor the epidemiology of neonates and young infants with enterovirus infections.