2022年3月，WHOから，新たなインフルエンザ治療ガイドライン，Guidelines for the clinical management of severe illness from influenza virus infectionsが発表された．ガイドラインは，欧米のインフルエンザに対する考え方を反映し，リスクのない健常人のインフルエンザ治療は対象としていない．インフルエンザ患者を，リスクを有する患者群とリスクのない患者群に分けて，リスク群には，全例に早期のオセルタミビル投与を推奨した．インフルエンザ検査として，感度，特異度の最も高い，Reverse Transcription Polymerase-chain-reaction（RT-PCR）検査のみを認め，RT-PCRができない環境では，検査をせず，ただちにオセルタミビルの投与開始を勧奨した．本ガイドラインでは，日本で広く使用されている吸入ラニナミビルと静注ペラミビルは，重症患者，ハイリスク患者の治療には「使用しない」ことが勧告された．また，ステロイド，受動免疫，マクロライドなどの補助的治療は全て実施すべきではないとされた．WHOガイドラインは，日本の実情にそぐわない面も多いが，各国のインフルエンザ対策に大きな影響を与えるものである．

A healthy, immunocompetent 15-year-old girl was admitted to our hospital with headache, fever, and loss of consciousness after vomiting. The vomiting and consciousness disturbance improved promptly without any specific treatment. While there was meningism, due to the persistent headache and fever, a CSF examination was performed on the fourth day of admission, which revealed lymphocytic pleocytosis, and varicella-zoster virus (VZV) DNA was detected by Multiplex PCR. The patient gave a history of having had chickenpox at 4 years of age. She received a 14-day course of intravenous acyclovir, and the treatment was switched to oral valacyclovir, given for another 3 days. She made a full recovery, with no residual neurologic deficit. The frequency of VZV meningitis in children is low, and there have been reports of a few cases without skin rash. It is possible that some cases diagnosed as cases of aseptic meningitis without skin rash may be cases of VZV meningitis. Multiplex PCR testing is considered as being an important tool for early diagnosis and appropriate treatment.

Strongyloidiasis, a parasitic infection caused by Strongyloides stercoralis, is widely prevalent in Asian and African tropical regions. Immunosuppressed patients are at a higher risk of developing Strongyloides hyperinfection/disseminated disease. A 30-year-old Nepalese man with a history of long-term prednisolone treatment for Type 2 Leprosy reaction developed diarrhea and anorexia. Blood culture yielded growth of Pseudomonas aeruginosa, and the patient was hospitalized for antibiotic treatment. However, the patient's gastrointestinal symptoms persisted even after discharge, necessitating readmission. S. stercoralis was detected in stool and duodenal biopsy specimens. Treatment with ivermectin was initiated at the dose of 12 mg/day (0.2 μg/kg/day); however, the patient's general condition deteriorated and he died of multi-organ failure despite intensive care. During hospitalization, the serum ivermectin levels were measured twice and the measured levels of 8.97 and 11.4 ng/mL suggested adequate absorption of ivermectin from the intestinal tract. Corticosteroids increase the blood levels of ecdysteroid-like substances, which stimulate the transformation of rhabditiform larvae into infective filariform larvae that potentially promotes hyperinfection and disseminated disease. In the age of globalization, we recommend S. stercoralis screening and prophylactic oral medication for patients predisposed to latent infection with the parasite who are receiving long-term immunosuppressive therapy.

We report a case of pulmonary nocardiosis caused by Nocardia otitidiscaviarum in a man diagnosed with idiopathic thrombocytopenia who was on oral prednisolone therapy. A chest PET/CT examination 13 days after the start of prednisolone therapy revealed a nodular shadow, and it progressively worsened and was accompanied by cavity formation over time. N. otitidiscaviarum was identified in bronchoalveolar lavage fluid by matrix assisted laser desorption ionization time of flight mass spectrometry. The isolate was eventually confirmed to be N. otitidiscaviarum by a 16S rRNA analysis. There was no evidence of disseminated disease. Combination therapy consisting of oral sulfamethoxazole-trimethoprim (SMX-TMP) and intravenous amikacin and imipenem was initiated, but the SMX-TMP was discontinued because of adverse effects. Antimicrobial susceptibility testing revealed that the isolate was non-susceptible to ceftriaxone, imipenem, minocycline, and clarithromycin. The patient declined long-term intravenous therapy. Oral ciprofloxacin was administered instead, and the pulmonary nocardiosis improved after 6 months of therapy. Bacterial identification and antimicrobial susceptibility testing influence the choice of treatment regimens for nocardia infections by N. otitidiscaviarum, which may be resistant to multiple antimicrobial agents.

A 56-year-old woman with a 9-month history of ulcerative colitis (UC) who had been treated with prednisolone (PSL) 40 mg/day and azathioprinefor 2 months was referred to our hospital because of fever and dyspnea. Computed tomography (CT) of the chest revealed diffuse ground-glass opacities in both lungs and consolidation in both lower lobes. PCR of the patient's bronchoalveolar lavage fluid was positive for pneumocystis jirovecii, and she was diagnosed with pneumocystis pneumonia (PCP). The patient developed refractory respiratory failure that required invasive mechanical ventilation. After sulfamethoxazole-trimethoprim administration and methyl prednisolone pulse therapy, her clinical condition improved dramatically. Few reports are available on severe PCP associated with UC. It is important to keep in mind the possibility of complication by PCP in UC patients.

COVID-19 is manifested by various symptoms and needs to be distinguished from other diseases. We report the case of a patient with Japanese spotted fever (JSF) who was admitted with a diagnosis of COVID-19. The patient was a 72-year-old woman with high fever whose SARS-CoV-2 rapid antigen test was positive. She also had rashes on her trunk and extremities, including on her palms and soles. We treated her as a COVID-19 patient, viewing her rashes as a complication of COVID-19 or a drug eruption. However, her fever and rashes persisted. Her medical history revealed a history of mowing, which involves a high risk of tick bites, and we discovered an eschar on her left popliteal fossa. We then suspected JSF and treated her with intravenous minocycline and levofloxacin as a severe case. PCR testing of specimens from the eschar was positive for Rickettsia japonica. A confirmatory SARS-CoV-2 PCR test and an anti-nucleocapsid antibody test were negative. We ultimately diagnosed the patient with JSF, not COVID-19. The number of JSF patients in Japan has increased in recent years. Since the clinical presentation of JSF patients and COVID-19 patients is similar, a careful medical history and physical examination are necessary to make the differential diagnosis.