腹泻都是诺如病毒引起的吗?
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腹泻都是诺如病毒引起的吗?

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最近,很多人因为腹泻呕吐来急诊看病,一天晚上,有位吃了火锅后腹泻患者受网上新闻的影响,非常担心自己是感染了该类病毒,非要让笔者给他详细辨别一下,看到后面还在排着的长队的候诊患者,于是想到这篇科普文章。


大多数的拉肚子最常见的不外乎吃的不合适、或是感染细菌、病毒、再或者肠道受凉刺激等引起的炎症反应。当然这里不包含那些疑难的炎性肠病、肿瘤性或麦胶性肠病。

诺如病毒感染最近越来越走进人们的视野,这和大家对感染性腹泻认识提高有关。前段时间的局部地区小流行已经被查出根源是生活污水的不合理排放引起。


1968年,美国诺瓦克镇一所小学发生急性胃肠炎暴发。1972年, Kapikian等科学家在此次暴发疫情的患者粪便中发现一种直径约27 nm的病毒颗粒, 将之命名为诺瓦克病毒(Norwalk virus)。此后,世界各地陆续从急性胃肠炎患者粪便中分离出多种形态与之相似但抗原性略异的病毒颗粒,统称为诺瓦克样病毒。在2002 年8月,第8届国际病毒命名委员会统一将诺瓦克样病毒改称为诺如病毒。


诺如病毒感染发病以轻症为主,最常见症状是腹泻和呕吐,其次为恶心、腹痛、头痛、发热、畏寒和 肌肉酸痛等,有研究发现成年人中腹泻更常见(72% vs 52%),而儿童比成年人更容易出现呕吐。大多数病程通常较短,症状持续时间平均为 2~3 天,但高龄人群和伴有基础性疾病患者恢复较慢。尽管诺如病毒感染主要表现为自限性疾病,但少数病例仍会发展成重症,甚至死亡,通常发生于高龄老人和低龄儿童。


诺如病毒具有明显的季节性,人们常把它称为“冬季呕吐病”。根据 2013年研究发现,全球52.7%的病例和41.2%的暴发发生在冬季,78.9%的病例和71.0%的暴发出现在凉爽的季节,也就是当下的季节并不是感染的高发季节。


诺如病毒传播途径包括人传人、经食物和经水传播。人传人可通过粪-口途径(包括摄入呕吐物产生的气溶胶)或间接接触被排泄物污染的环境而传播。食源性传播是通过食用被诺如病毒污染的食物进行传播,牡蛎等贝类海产品和生食的蔬果类是引起暴发的常见食品。经水传播可由桶装水、市政供水、井水等其他饮用水源被污染所致。


目前,尚无针对诺如病毒的特异抗病毒药和疫苗,其预防控制主要采用非药物性预防措施,包括病例管理、手卫生、环境消毒、食品和水安全管理、风险评估和健康教育。这些措施既适用于聚集性和暴发疫情的处置,也适用于散发病例的预防控制。作为一种公共卫生传染病要积极配合疾控中心进行疾病的管控与隔离治疗。


保持良好的手卫生是预防诺如病毒感染和控制传播最重要最有效的措施。应按照标准的 6 步洗手法正确洗手,采用肥皂和流动水至少洗20s。需要注意的是,消毒纸巾和免冲洗的手消毒液不能代替标准洗手程序。


Recently, manypeople came to see a doctor in emergency department because of diarrhea andvomiting. One night, a patient with diarrhea after eating chafing dish wasaffected by the news on the Internet. He was very worried that he was infectedwith this kind of virus. He had to be identified in detail by the author. Hesaw a long queue of waiting patients in the back, so he thought of this popularscience article.


The most commoncause of diarrhea is inappropriate diet, infection with bacteria, viruses, orcold irritation of the intestine. Of course, there are no difficultinflammatory bowel diseases, tumors or gummy bowel diseases.


Noirovirusinfection has recently become more and more popular, which is related to theincreased awareness of infectious diarrhea. Some time ago, local pandemics havebeen found to be caused by unreasonable discharge of domestic sewage.


In 1968, anoutbreak of acute gastroenteritis occurred in a primary school in Nowak Town,USA. In 1972, Kapikian and other scientists discovered a virus particle about27 nm in diameter in the feces of patients with the outbreak, which was namedNorwalk virus. Since then, various viral particles with similar morphology butslightly different antigenicity have been isolated from the feces of patientswith acute gastroenteritis worldwide, collectively known as Norwalk-like virus.In August 2002, the 8th International Virus Nomenclature Committee changed thename of Norwalk-like virus to Norovirus.


Norovirusinfection is mainly mild, the most common symptoms are diarrhea and vomiting,followed by nausea, abdominal pain, headache, fever, chills and musclesoreness. Studies have found that diarrhea is more common in adults (72% vs52%) and children are more likely to vomit than adults. Most of the course ofdisease is usually short, the duration of symptoms is 2 to 3 days on average,but the elderly and patients with underlying diseases recover slowly. AlthoughNorovirus infection is mainly manifested as self-limiting disease, a few casesstill develop into severe or even death, usually occurring in the elderly andyoung children.


Norovirus hasobvious seasonality, which is often called "winter vomiting disease".According to the 2013 study, 52.7% of cases and 41.2% of outbreaks occur inwinter, 78.9% of cases and 71.0% of outbreaks occur in the cool season, thatis, the current season is not the season of high incidence of infection.


Norovirustransmission routes include human-to-human transmission, food and water transmission.Human-to-human transmission can occur through fecal-oral pathways (includingaerosols from vomiting intake) or indirect exposure to the environmentcontaminated by excreta. Food-borne transmission is carried out by eating foodcontaminated by Norovirus. Shellfish, seafood such as oysters and rawvegetables and fruits are common foods causing outbreaks. Water transmissioncan be caused by contamination of barreled water, municipal water supply, wellwater and other drinking water sources.


At present, thereare no specific antiviral drugs and vaccines against Norovirus. Non-drugpreventive measures are mainly used for its prevention and control, includingcase management, hand hygiene, environmental disinfection, food and watersafety management, risk assessment and health education. These measures areapplicable not only to the disposal of aggregation and outbreaks, but also tothe prevention and control of sporadic cases. As a public health infectiousdisease, we should actively cooperate with CDC for Disease Control andisolation treatment.


Maintaining goodhand hygiene is the most important and effective measure to prevent Norovirusinfection and control transmission. Hands should be washed correctly inaccordance with the standard six-step washing method, using soap and flowingwater for at least 20 seconds. It should be noted that disinfection papertowels and hand sanitizers without rinsing can not replace the standard handwashing procedures.


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