抗原定性検査と逆転写酵素ポリメラーゼ連鎖反応（RT-PCR：Reverse Transcription-Polymerase Chain Reaction）の新型コロナウイルス検出に関する比較試験はこれまでにも行われているが，感染性を有する患者の特定に関する差については分かっていない．抗原定性検査，RT-PCR検査を入院時に同時に採取し，2021年2月21日から2021年10月8日に入院した患者1,101人に対してスクリーニングを行ない，それぞれの検査が感染性を有する患者の特定にどのように寄与したのかを後ろ向きに検討した．検査結果が乖離した症例は7例あり全て抗原定性検査陰性，RT-PCR検査陽性だった．いずれの検査も陽性が9例，いずれも陰性が1,085例だった．抗原定性陰性，RT-PCR検査陽性となった7例中6例が最終的に感染性はないと判断された．また，7例中1例が感染性あると判断され，この症例は肺炎を伴っていた．研究期間内の感染性を有する患者の検出に関して，症状や暴露状況から新型コロナウイルス感染の事前確率が高い場合は抗原定性検査よりRT-PCR検査が有用だった症例が1例あったが，無症状かつ暴露がない場合には抗原定性検査とRT-PCR検査は同等だった．

背景：本邦では結核菌ゲノム解析と実地疫学を組み合わせた積極的結核疫学調査の有用性評価は行われていない．

方法：2009～2020年の山形県における反復配列多型（VNTR）分析に基づいた網羅的な結核分子疫学調査結果により見出されたクラスターのうち，2020年の結核患者8人を含む8クラスター（19人）を対象に結核菌ゲノム比較を実施し，保健所の実地疫学調査結果と併せて評価した．

結果：結核菌ゲノム比較の結果，近縁株（一塩基多型5カ所以内，もしくは6～12カ所かつ患者間に疫学的関連性を確認）は19株中9株（47.4%）に留まり，半数の4クラスターにのみ近縁株が含まれた．また，近縁株患者9人中6人（66.7%）で患者間の疫学的関連性が見出されていた一方，分離された菌が患者間の最近の結核感染伝播を示唆しない非近縁株（一塩基多型13カ所以上）であった10人は，全例が疫学的関連性不明であった（p＜0.01）．

結論：高精細な識別能を有する結核菌ゲノム解析は，VNTR分析によりクラスターを形成した菌株から，患者間の疫学的関連性を強く示唆する近縁株を選別することができた．その特長は，保健所の感染伝播経路調査に要する人的・時間的資源を必要な結核患者に集中させることを可能とし，効率的かつ高精度の積極的結核疫学調査に貢献するものと考えられた．

千葉県小児災害対策ネットワーク参加施設（38医療機関，県内の全2次医療圏をカバー）を対象に，千葉県の小児新型コロナウイルス感染症（coronavirus disease 2019：COVID-19）入院例について後方視的に検討した．流行第1波～第5波（2020年3月～2021年12月）は観察研究で集計した155例（年齢中央値6歳10カ月）を，第6波（2022年1月～5月）はメーリングリストで集計した354例（同3歳）を対象とした．ピーク月の比較で，第6波は第5波までの5倍の入院数を認めた．第5波までは軽症例（発熱のみ，上気道炎，無症状）が9割を占めたが，重症肺炎が1例見られた．一方，第6波では，痙攣（19.5%），クループ症状（4.5%）での入院例が増加した．痙攣のうち重積が42%，群発が30.4%を占め，3例が脳炎・脳症と診断された．また，この3例を含む13例（3.7%）が集中治療室管理またはそれに準ずる治療を要した．第6波での新型コロナワクチン2回接種完了者は，5～11歳で2.6%，12歳以上で40%と低率であった．このように，第6波の主体であったオミクロン株流行期には，小児COVID-19患者の症状に変化が見られた．また，入院例での新型コロナワクチン接種率は低く，重症化予防の観点から，小児へのワクチン接種の積極的推奨の重要性が示唆された．

We report a case of an 82-year-old woman who developed an atraumatic rectus sheath hematoma (RSH) during the treatment for severe Japanese spotted fever (JSF). She had fever, skin rash, and eschar, thrombocytopenia, elevated liver enzymes and inflammatory markers. Rickettsial infection was considered likely, empiric antibiotic therapy was initiated with intravenous minocycline (MINO) and meropenem for septic shock. On day 2, vancomycin and noradrenaline were added due to decreased blood pressure and loss of consciousness. On day 4, she was definitively diagnosed as JSF by reverse transcription PCR. Only MINO was continued due to stabilization of her condition. However, anemia and thrombocytopenia persisted on day 5. CT scan on day 5 revealed a 3cm expanding RSH with extravasation, not present on day 4. She was transported by helicopter for transcatheter arterial embolization.

The number of JSF cases is increasing every year in Japan. Some JSF cases lead to DIC. On the other hand, RSH is a relatively rare disease caused by sudden muscle rupture or disruption of the upper and lower abdominal wall arterioles.

We suspected hematoma formation in our patient because of the persistent anemia and thrombocytopenia, which was different from the usual course of improvement in JSF. Continued monitoring with attention to laboratory findings led to early detection. We conducted a retrospective review of 13 patients with JSF at our institution for the past 10 years.

To our best knowledge, this is the first report of JSF complicated with RSH.

We report the case of a Vietnamese man in his twenties who presented with a few days' history mild fever and severe pain in the right hypochondrium. Laboratory findings showed elevated levels of the hepatobiliary enzymes and marked peripheral blood eosinophilia. Abdominal computed tomography (CT) showed map-like low density areas with unclear boundaries under the liver capsule. Suspecting a parasitic infection, we conducted enzyme linked immunosorbent assay (ELISA) for a panel of parasite antigens, including Fasciola antigen. However, no positive results for any parasites were obtained. Re-examination by contrast-enhanced CT revealed that the hepatic mass had moved and findings suggestive of perihepatic inflammation. Fascioliasis was suspected, and the ELISA for Fasciola antigen was repeated again after a period of time, but the result was again negative. Despite the negative test result, the patient was diagnosed as having fascioliasis, based on the severe pain in the right abdomen, persistent eosinophilia, and mobile liver mass, all of which are characteristic symptoms of fascioliasis. For the treatment with triclabendazole (TCB), he was referred to a hospital in the Research Group on Chemotherapy of Tropical Diseases, Japan, which imports nationally unlicensed medicines, including TCB. After the patient received treatment with TCB (10mg/kg), the symptoms disappeared, and the eosinophil counts decreased. Serological testing at 4 weeks after the TCB administration revealed positive antibody results for crude as well as recombinant Fasciola antigen. Fascioliasis is a relatively rare disease, with only few cases per year reported in Japan. There are no worm eggs in the feces in the acute phase, and serological analysis (such as antibody testing) is the basis for the diagnosis. However, in this case, tests for the fasciola antibody initially remained negative. It should be noted that serological analysis can be negative in the early stage of the disease.

Severe hepatitis is rarely seen in pediatric patients with coronavirus disease 2019 (COVID-19), except in association with multisystem inflammatory syndrome in children/pediatric inflammatory multisystem syndrome (MIS-C/PIMS) or with severe disease. Here, we present the case of an 8-year-old Japanese boy with mild COVID-19 who developed hepatitis. The patient was in good general condition without fever or respiratory symptoms, but had severe acute hepatitis that resolved spontaneously. Severe acute hepatitis of unknown etiology in children has been recently reported worldwide, and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been identified in some patients. However, this is the first case report from Japan of severe acute hepatitis associated mild COVID-19 in a child.