Rapid detection and clinical features of infants and young children with acute lower respiratory tract infection due to respiratory syncytial virus

During December to the end of February of 2003 and 2004, a total of 282 nasopharyngeal aspirates were obtained from infants and young children admitted to the Buraidah Maternity and Pediatric Hospital, Al-Qassim, Saudi Arabia, and clinically diagnosed as suffering from acute lower respiratory tract infections. The aspirates were tested for the presence of respiratory syncytial virus using direct fluorescein-labeled monoclonal antibody assay. Of the 282 specimens, 128 (45.4%) were found to be positive for respiratory syncytial virus. The most positive specimens came from patients less than one year old (51.3%), and were associated with bronchopneumonia (56.7%) or bronchiolits (55.4%). Coughing (100%) and tachpnea (98%) were significantly more frequent in infants with respiratory syncytial virus infection, followed by wheezing, crepitation and retraction, each representing 66%. Three deaths were reported. The availability of a rapid viral diagnostic assay will be an important tool for physicians to make more accurate treatment decisions and therefore reduce unnecessary antibiotic usage and hospital stay for the patients.     

冬季急性下呼吸道感染住院儿童病原学分析及临床流行病学特点

目的了解冬季儿童急性下呼吸道感染病原谱及临床流行病学特征,为临床抗感染及病原检测提供依据。方法对我院2006年12月～2007年2月急性下呼吸道感染住院患儿采用一次性无菌吸痰管经鼻腔插入7～8cm,达到咽部以下负压吸取1～2ml深部鼻咽分泌液送细菌培养,并对呼吸道合胞病毒(RSV),腺病毒(ADV),A、B型流感病毒(IFV),1、2及3型副流感病毒(PIV)等7种常见呼吸道病毒抗原进行检测及运用荧光定量聚合酶链反应(PCR)技术检测标本中支原体和衣原体DNA。结果①381份下呼吸道感染儿童痰标本中细菌培养阳性81份,病毒检测阳性133份,支原体和衣原体阳性分别12份与6份,混合感染标本44份,总标本病原学检出率为50.66%(193/381)。②RSV阳性标本112份,为最重要的感染病原,连续3个月RSV检出率均在30%左右,6月龄以下儿童占61.61%,2岁以下儿童占86.61%,阳性标本中78.57%的患儿有喘息表现。③大肠埃希菌(16株)、肺炎链球菌(14株)、肺炎克雷伯菌及金黄色葡萄球菌(各10株)、卡他莫拉菌布兰汉亚种(8株)、流感嗜血杆菌和副流感嗜血杆菌(各6株)表现为主要的致病菌。结论RSV感然仍为儿童冬季急性下呼吸道感染最主要的病原,尤其在2岁以下儿童,且易表现为喘息发作。仍有40%以上感染病原未明,儿童急性下呼吸道感染病原谱需进一步完善。     

Evolution of infection in mice inoculated by the oral route with different developmental forms of Trypanosoma cruzi I and II

Oral infection has become the most important transmission mechanism of Chagas disease in Brazil. For this study, the development of Trypanosoma cruzi infection in mice, induced by the oral and intraperitoneal (IP) routes, was compared. Four groups of Swiss mice were used to evaluate the influence of parasite genetics, number of parasites, inoculation volume and developmental stages on the development of the orally induced infection: 1 – blood trypomastigotes (BT) via oral; 2 – BT via IP; 3 – culture metacyclic trypomastigotes (MT) via oral; and 4 – culture MT via IP. Animals inoculated orally showed levels of parasitemia, as well as infectivity and mortality rates, lower than animals inoculated via IP, regardless of DTU (discrete typing unit) and inoculum. Animals infected with TcII showed higher levels of these parameters than did animals infected with TcI. The larger volume of inoculum showed a greater capacity to cause an infection when administered via the oral route. BT infection was more virulent than culture MT infection for both routes (oral and IP). However, mice inoculated orally with BT showed lower levels than via IP, while mice inoculated orally with culture MT showed similar levels of infection to those inoculated via IP. Mice inoculated with culture MT showed more histopathological changes than those inoculated with BT, regardless of the inoculation route. These results indicate that this alternative experimental model is useful for evaluating infection by T. cruzi isolates with subpatent parasitemia and low virulence, such as those belonging to the TcI and TcIV DTUs, which are prevalent in outbreaks of orally transmitted Chagas disease.