家族に流行性耳下腺炎、予防接種したほうがよい?

 
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  1週間前に子供さんが流行性耳下腺炎(おたふくかぜ)を発症。治癒証明をもらいに受診した際、お母さんからの、お母さん自身に関するご質問です。

 「自分はおたふくかぜにかかったことがなく、予防接種もしていないと思います。予防のために、予防接種をしておきたいのですが。」

  流行性耳下腺炎の接触者予防(PEP: postexposure prophylaxis)に関するご質問です。

  残念ながらご自身も発熱しており接種は不適格でしたが、流行性耳下腺炎のPEPについて、効果はどのようなものなのでしょうか。少し調べてみることにしました。

 

流行性耳下腺炎のPEP

 よく引用されている、CDC(米国疾病管理予防センター)のレポートから。

Centers for Disease Control and Prevention. Measles, mumps, and rubella—vaccine use and strategies for elimination of measles, rubella, and congenital rubella syndrome and control of mumps: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep. 1998; 47(RR-8):1-57.
http://www.cdc.gov/mmwr/PDF/rr/rr4708.pdf

  Postexposure MMR vaccination does not prevent or alter the clinical severity of rubella or mumps. However, widespread vaccination during a mumps outbreak may help terminate such outbreaks *1.

  If exposure to measles, rubella, or mumps does not cause infection, postexposure vaccination with MMR should induce protection against subsequent infection. If the exposure results in infection, no evidence indicates that administration of MMR vaccine during the presymptomatic or prodromal stage of illness increases the risk for vaccine-associated adverse events.


 接触後のワクチンは流行性耳下腺炎の予防や軽症化に役立たない、という記載があります。

 

 Health Protection Agency(英国健康保護局, HPA)のウェブサイトには、同様の質問とその答えが記載されています。

Health Protection Agency

Frequently Asked Questions about Mumps


Q. Should MMR be used for post-exposure prophylaxis?

A. Antibody response to the mumps component of MMR vaccine does not develop soon enough to provide effective prophylaxis after exposure to suspected mumps. Even where it is too late to provide effective post-exposure prophylaxis with MMR, the vaccine can provide protection against future exposure to all three infections. Therefore, contact with suspected measles, mumps or rubella, provides a good opportunity to offer MMR vaccine to previously unvaccinated individuals. If the individual is already incubating measles, mumps or rubella, MMR vaccination will not exacerbate the symptoms. In these circumstances individuals should be advised that a mumps-like illness occurring shortly after vaccination is likely to be due to natural infection. If there is doubt about an individual's vaccination status, MMR should still be given as there are no ill effects from vaccinating those who are already immune.

 

 接触後ではワクチンの予防効果を期待するには遅すぎる、とあります。ただ、ワクチン未接種の人にとっては、むしろワクチン接種の良いタイミングとなる、ということです。

 

 CDCにも記載されていましたが、もし発症したとしても、ワクチンを接種したことによる害はみられない、とのことです。

 

PEPが有効な感染症は?

 PubMedからひとつ論文を紹介します。原著未入手のため抄録のみです。

Lutwick LI. Postexposure prophylaxis. Infect Dis Clin North Am. 1996 Dec;10(4):899-915. Review. PubMed PMID: 8958174.

The timely facilitation of immunologic (immunoglobulin or vaccine) or antimicrobial prophylaxis is used in individuals who have been exposed to certain infectious diseases. Such methodology has been shown to be helpful in infections such as viral hepatitis types A and B, measles, varicella, rabies, and tuberculosis. The data supporting such use in rubella and mumps are not strong and information is still needed in hepatitis C, human immunodeficiency virus, and Lyme borreliosis. This article reviews postexposure prophylaxis in these situations. Preventive strategies for meningococcal disease, group A streptococcus, tetanus, diphtheria, and pertussis are discussed elsewhere in this issue.

 

 接触後予防が有効なのは、A型肝炎、B型肝炎、麻疹、帯状疱疹、狂犬病、結核と記載されています。覚えておきたいです。

 

*1:Wharton M, Cochi SL, Hutcheson RH, Bistowish JM, Schaffner W. A large outbreak of mumps in the postvaccine era. J Infect Dis 1988;158:1253–60.