Department of Neurology, Telemark Hospital, Skien, Norway.
MS Research Group, Oslo University Hospital, Oslo, Norway.
Acta Neurol Scand. 2017 Nov;136 Suppl 201:26-30. doi: 10.1111/ane.12844.
The hygiene hypothesis, suggesting that low exposure to pathogens early in life can increase the risk for immune-mediated diseases, has been proposed as an explanation for the increase in incidence of allergy and autoimmune diseases in industrialized countries during the last decades. Several aspects of the hygiene hypothesis have been related to MS. Already in 1966, the risk of MS was suggested to be higher in individuals with high hygienic standard during childhood. Further, an episode of infectious mononucleosis is an independent risk factor for MS and can be regarded as an indicator of low exposure to pathogens early in life, as infection with Epstein-Barr virus often is asymptomatic when it occurs in young children. Conflicting results have been reported regarding number of siblings, attendance in a day care center and exposure to animals during childhood in relation to MS risk, but common childhood infections and vaccinations do not seem to influence the risk of MS. In line with the hygiene hypothesis, two large meta-analyses have recently shown that infection with Helicobacter pylori is negatively correlated with MS. Moreover, a protective influence of helminth infection on MS has been observed in several, small clinical studies, but more knowledge is needed before a potential role of helminth-derived therapy in MS is determined. Also, it has been hypothesized that infection with the parasite Toxoplasma gondii could be protective against MS.
卫生假说认为，生命早期接触病原体的机会较少会增加免疫介导性疾病的风险，这一假说被认为是解释过去几十年中工业化国家过敏和自身免疫性疾病发病率上升的原因。卫生假说的几个方面与多发性硬化症有关。早在 1966 年，就有人提出，儿童时期卫生标准较高的人患多发性硬化症的风险更高。此外，传染性单核细胞增多症的发作是多发性硬化症的一个独立危险因素，可被视为生命早期接触病原体机会较少的一个指标，因为儿童时期感染 Epstein-Barr 病毒通常无症状。关于多发性硬化症风险与儿童时期兄弟姐妹数量、日托中心出勤率和接触动物之间的关系，已有报道结果相互矛盾，但常见的儿童感染和疫苗接种似乎不会影响多发性硬化症的风险。与卫生假说一致，最近两项大型荟萃分析表明，幽门螺杆菌感染与多发性硬化症呈负相关。此外，在几项小型临床研究中观察到寄生虫感染对多发性硬化症的保护作用，但在确定寄生虫源性治疗多发性硬化症的潜在作用之前，还需要更多的知识。此外，还假设寄生虫刚地弓形虫感染可能对多发性硬化症有保护作用。
