WM Chan, SY Lee, YW Kwan, CB Chow, CW Leung

Abstract

Background: Measles still causes significant morbidity and mortality. The diagnosis of measles relies on early recognition of clinical manifestations. We identified a group of young infants who presented with a modified clinical picture after contracting measles, but there is scarce literature describing this observation. Method: We conducted a retrospective study of all infants <1 year old with measles confirmed by serological or virological methods in Princess Margaret Hospital, a territory-wide tertiary referral centre for infectious diseases in Hong Kong, over a period of 10 years from 1999 to 2008. The study population (n=165) was divided into 2 groups: 29 infants were aged <7 months and 136 infants were 7-12 months of age. Their clinical manifestations were compared and analysed, which included the timing of skin rash in relation to onset of fever, duration of fever, presence or absence of characteristic clinical features of measles such as coryza, cough, conjunctivitis, Koplik's spots, staining of convalescent rash, and other associated features and complications. Results: The mean duration of fever in infants aged <7 months and 7-12 months were 4.6 and 6.8 days, respectively (p<0.001, 95% CI 1.24-3.04). Shorter duration of fever was noted in the younger age group with a positive correlation observed for age and duration of fever (r=0.307, p<0.001). The onset of skin rash was 2.3 and 3.7 days after the onset of fever for the 2 age groups, respectively (p=0.001, 95% CI 0.58-2.12). Earlier onset of skin rash was noted in the younger age group with a positive correlation observed for age and timing of skin rash from the onset of fever (r=0.255, p=0.001). Conjunctivitis (p=0.001) and staining of skin rash during convalescence (p=0.026) were significantly less common in the younger infant group. There were no significant differences between the 2 groups regarding presence of coryza (p=0.07), cough (p=0.28), Koplik's spots (p=0.18), diarrhoea (p=0.72), pneumonia (p=0.74) and the use of antibiotics (p=0.74). Conclusion: Our study revealed a modified clinical picture of non-specific and milder form of measles in young infants. The presence of modified features may be due to partial protection provided by maternally derived measles antibody (anti-measles IgG). We should maintain a high index of suspicion for measles presenting in this group of patients because of the possibility of atypical presentation. The use of rapid diagnostic test (e.g. anti-measles IgM) in such situation facilitates early diagnosis, proper treatment and institution of appropriate infection control measures. Early airborne isolation of hospitalised infants should be considered in all suspected cases to interrupt transmission and prevent potential nosocomial outbreaks.

背景：麻疹仍有明顯的發病率及死亡率。麻疹的診斷依賴於臨床表現的早期識別。我們確診了一組患有麻疹的嬰幼兒，其臨床表現不典型，但是很少有相關文獻的報導。方法：我們回顧性研究了1999-2008年，這 10年裏所有在瑪嘉烈醫院（香港地區接收傳染性疾病的一間三級醫院），通過血清和病毒學檢查確診的患麻疹的<1歲的嬰幼兒。研究物件（n=165）分為2組：1組為29名小於7個月的嬰兒，一組為136名7-12月大的嬰兒。將他們的臨床表現進行比較和分析，包括皮疹與發熱的時間，發熱持續的時間，是否存在麻疹的典型臨床表現，如卡他症狀，咳嗽，結膜炎，口腔的克氏斑，恢復期的皮膚色素沉著和其他相關的特點和併發症。結果：在<7月和7-12月大的嬰兒的平均發熱時間分別為4.6和6.8天（p<0.001,95% CI 1.24-3.04）。小年齡組中發現其發熱時間較短，年齡與發熱持續的時間呈正相關的關係（r=0.307，p<0.001）。在兩組病人中，皮疹分別在發熱後2.3和3.7天後出現（p<0.001,95% CI 0.58-2.12）。在小年齡組病人中，皮疹出現的較早，年齡與發熱後皮疹出現的時間呈正相關（r=0.255，p=0.001）。結膜炎（p=0.001）和恢復期皮膚的色素沉著（p=0.026）在小年齡組中的並不常見。兩組病人在鼻炎症狀（p=0.07），咳嗽（p=0.28），口腔的克氏斑（p=0.18），腹瀉（p=0.72），肺炎（p=0.74）和抗生素的使用（p=0.74）中無明顯不同。結論：我們的研究顯示，在小年齡的嬰兒中，有不典型的臨床表現和更溫和的麻疹的表現形式。其不典型的表現可能是源自從母體獲得的麻疹抗體（麻疹抗體IgG）的局部保護作用。可能由於其不典型的表現，我們對這組病人是否有麻疹始終保持高度懷疑。在此情況下使用快速診斷（如麻疹抗體-IgM的檢測）有利於早期診斷，妥善治療和醫療機構的感染控制。在所有疑似麻疹的住院嬰兒中進行早期的空氣隔離，可以中斷傳播途徑和防止潛在的院內爆發性感染的發生。