Exanthem subitum (Roseola infantum)

Japanese: 突発性発疹（小児バラ疹） - とっぱつせいほっしん（しょうにバラしん）（英語表記）Exanthem subitum (Roseola infantum)

What kind of infection is it?

This is an acute viral infection caused by human herpesvirus 6 or 7, which most commonly occurs in children between 6 months and 1 year of age.

It is said that most children are infected by the age of 3. Since human herpesvirus 6 is more likely to infect earlier than 7, it is thought that the first roseola is usually caused by 6, and the second by 7.

How symptoms manifest

After a fever of 38-39°C continues for 3-4 days, the fever subsides and a rash appears all over the body. The rash disappears in 2-3 days. Other than fever and rash, diarrhea is a relatively common symptom. cough ( cough ) Although some patients may have a runny nose or a cold, respiratory symptoms are generally few. In addition, febrile convulsions may occur during the fever period.

Traditionally, this disease has been said to have a good prognosis, but in rare cases it can develop into encephalitis or hepatitis. Therefore, if your child has any unusual symptoms other than fever and rash, or if their overall condition is poor, you should visit your pediatrician as soon as possible.

Testing and diagnosis

Diagnosis is usually made based on characteristic clinical symptoms, but to prove infection with human herpesvirus 6 or 7, blood samples are taken during the acute and recovery phases of the disease to confirm that antibodies turn positive, the virus is isolated from blood during the acute phase, and the viral gene (DNA) is detected in acute phase serum using the PCR method.

Another disease that must be distinguished is enterovirus infection.

Treatment methods

Symptomatic treatment (hydration, cooling and antipyretics in case of fever, in case of severe diarrhea, intestinal regulators and Antidiarrheal drugs ( Understanding ) If febrile convulsions occur, they usually subside within a few minutes and leave no aftereffects, but in rare cases, if symptoms such as prolonged convulsions, unilateral convulsions, symptoms reminiscent of post-convulsive paralysis, or a decreased level of consciousness are observed, it is necessary to immediately visit a hospital.

What to do if you notice an illness

If your child only has a fever, is in a good mood, and has no overall condition, there is no need to rush to the emergency room; however, since it is difficult to determine at home what is causing the fever at the beginning of the illness, it is necessary to take your child to your paediatrician.

Kaoruko Taya

Source: Houken “Sixth Edition Family Medicine Encyclopedia” Information about the Sixth Edition Family Medicine Encyclopedia

Japanese:

どんな感染症か

　生後6カ月～1歳台の小児に好発する、ヒトヘルペスウイルス6あるいは7による急性ウイルス感染症です。

　ほとんどの子どもが3歳までに感染するといわれています。感染する時期はヒトヘルペスウイルス6のほうが7よりも早いことが多いため、1度目の突発性発疹は6、2度目は7による感染症のことが多いと考えられます。

症状の現れ方

　38～39℃台の発熱が3、4日続いたのち、解熱とともに全身に発疹が現れます。発疹は2、3日で消失します。発熱と発疹以外に比較的多くみられる症状として下痢があります。咳(せき)や鼻水を伴う場合もありますが、通常、呼吸器症状は少ないと考えられます。また、発熱の時期に熱性けいれんを合併することがあります。

　従来、予後良好な疾患といわれていますが、まれに脳炎や肝炎を併発することがあるので、発熱、発疹以外に普段と異なる症状を認めたり全身状態が悪い場合は、早めにかかりつけの小児科を受診することが必要です。

検査と診断

　診断は特徴的な臨床症状から行うことがほとんどですが、ヒトヘルペスウイルス6あるいは7の感染を証明するためには、病気の急性期と回復期で採血して抗体が陽性に転じることを確認する、急性期の血液からウイルスを分離する、急性期の血清からPCR法でウイルスの遺伝子（DNA）を証明するなどの方法が用いられています。

　区別すべき病気として、エンテロウイルス感染症があります。

治療の方法

　対症療法（水分補給、発熱時は冷却や解熱薬の投与、下痢がひどい場合は、整腸薬や止痢薬(しりやく)など）で通常は回復します。熱性けいれんを合併した場合、通常けいれんは数分でおさまり、後遺症は残りませんが、まれに、けいれんの持続時間が長い、片側のけいれん、けいれん後の麻痺を思わせる症状、意識レベルが低下するなどの症状を認めた場合は、早急に病院を受診する必要があります。