Resurgence of human metapneumovirus infection and influenza after three seasons of inactivity in the post-COVID-19 era in Hokkaido, Japan, 2022-2023.

Following the coronavirus disease 2019 (COVID-19) outbreak in February 2020, incidences of various infectious diseases decreased notably in Hokkaido Prefecture, Japan. However, Japan began gradually easing COVID-19 infection control measures in 2022. Here, we conducted a survey of children hospitalized with human metapneumovirus (hMPV), influenza A and B, and respiratory syncytial virus infections in 18 hospitals across Hokkaido Prefecture, Japan, spanning from July 2019 to June 2023. From March 2020 to June 2022 (28 months), only 13 patients were hospitalized with hMPV, and two patients had influenza A. However, in October to November 2022, there was a re-emergence of hMPV infections, with a maximum of 27 hospitalizations per week. From July 2022 to June 2023 (12 months), the number of hMPV-related hospitalizations dramatically increased to 317 patients, with the majority aged 3-6 years (38.2%, [121/317]). Influenza A also showed an increase from December 2022, with a peak of 13 hospitalizations per week in March 2023, considerably fewer than the pre-COVID-19 outbreak in December 2019, when rates reached 45 hospitalizations per week. These findings suggest the possibility of observing more resurgences in infectious diseases in Japan after 2023 if infection control measures continue to be relaxed. Caution is needed in managing potential outbreaks.

Changing Patterns of Infectious Diseases Among Hospitalized Children in Hokkaido, Japan, in the Post-COVID-19 Era, July 2019 to June 2022.

BACKGROUND: Many reports have reported a reduction in respiratory infectious diseases and infectious gastroenteritis immediately after the coronavirus disease 2019 (COVID-19) pandemic, but data continuing into 2022 are very limited. We sought to understand the current situation of various infectious diseases among children in Japan as of July 2022 to improve public health in the post-COVID-19 era. METHODS: We collected data on children hospitalized with infectious diseases in 18 hospitals in Japan from July 2019 to June 2022. RESULTS: In total, 3417 patients were hospitalized during the study period. Respiratory syncytial virus decreased drastically after COVID-19 spread in early 2020, and few patients were hospitalized for it from April 2020 to March 2021. However, an unexpected out-of-season re-emergence of respiratory syncytial virus was observed in August 2021 (50 patients per week), particularly prominent among older children 3-6 years old. A large epidemic of delayed norovirus gastroenteritis was observed in April 2021, suggesting that the nonpharmaceutical interventions for COVID-19 are less effective against norovirus. However, influenza, human metapneumovirus, Mycoplasma pneumoniae , and rotavirus gastroenteritis were rarely seen for more than 2 years. CONCLUSIONS: The incidence patterns of various infectious diseases in Japan have changed markedly since the beginning of the COVID-19 pandemic to the present. The epidemic pattern in the post-COVID-19 era is unpredictable and will require continued careful surveillance.

Surveillance in hospitalized children with infectious diseases in Japan: Pre- and post-coronavirus disease 2019.

INTRODUCTION: The epidemic of coronavirus disease 2019 (COVID-19) rapidly spread worldwide, and the various infection control measures have a significant influence on the spread of many infectious diseases. However, there have been no multicenter studies on how the number of hospitalized children with various infectious diseases changed before and after the outbreak of COVID-19 in Japan. METHODS: We conducted a multicenter, prospective survey for hospitalized pediatric patients in 18 hospitals in Hokkaido Prefecture, Japan, from July 2019 to February 2021. We defined July 2019 to February 2020 as pre-COVID-19, and July 2020 to February 2021 as post-COVID-19. We surveyed various infectious diseases by sex and age. RESULTS: In total, 5300 patients were hospitalized during the study period. The number of patients decreased from 4266 in the pre-COVID-19 period to 701 (16.4%) post-COVID-19. Patients with influenza and RSV decreased from 308 to 795 pre-COVID-19 to zero and three (0.4%) post-COVID-19. However, patients with adenovirus (respiratory infection) only decreased to 60.9% (46-28) of pre-COVID levels. Patients with rotavirus, norovirus, and adenovirus gastroenteritis decreased markedly post-COVID-19 to 2.6% (38-1), 27.8% (97-27) and 13.5% (37-5). The number of patients with UTIs was similar across the two periods (109 and 90). KD patients decreased to 31.7% (161-51) post-COVID-19. CONCLUSIONS: We suggest that current infection control measures for COVID-19 such as wearing masks, washing hands, and disinfecting hands with alcohol are effective against various infectious diseases. However, these effects vary by disease.

Familial Mediterranean Fever After Cord Blood Transplantation for Familial Hemophagocytic Lymphohistiocytosis.

Familial Mediterranean fever (FMF) is a hereditary autoinflammatory disorder accompanied by periodic fever and sterile serositis. We report a 5-year-old boy with FMF, who underwent second unrelated cord blood transplantation (CBT) for recurrent familial hemophagocytic lymphohistiocytosis. Periodic attacks of fever and abdominal pain started 6 months after CBT. He was diagnosed with FMF according to the Tel-Hashomer criteria and treated successfully with colchicine. Genetic testing showed heterozygous p.E148Q mutation in the MEFV gene from both donor and recipient cells. Several CBT-related factors including use of an immunosuppressant can potentially be involved in the pathogenesis of FMF in our patient.

Macrophage activation syndrome in neonates born to mothers with adult-onset Still's disease: Perinatal effect of maternal IL-18.

Overproduction of interleukin (IL)-18 is closely related to the pathogenesis of adult-onset Still's disease (AOSD) and the development of macrophage activation syndrome (MAS), a life-threating complication of AOSD. We reported three cases of MAS occurring in infants born to mothers with AOSD. The infants developed MAS at age 13 and 8 days and at birth. Serum IL-18 levels were extremely elevated in all infants (147,000 pg/mL; 378,000 pg/mL; 95,000 pg/mL) as well as in their mothers (58,500 pg/mL; 367,000 pg/mL; 84,000 pg/mL). Physicians should be aware that infants born to mothers with AOSD are at a risk of developing MAS. Serum IL-18 levels in mothers with AOSD and their infants should be monitored.

Intravenous abatacept in Japanese patients with polyarticular-course juvenile idiopathic arthritis: results from a phase III open-label study.

BACKGROUND: To investigate efficacy and safety of intravenous abatacept in Japanese patients with active polyarticular-course juvenile idiopathic arthritis (pJIA). METHODS: In this phase III, open-label, multicenter, single-arm study, patients with pJIA aged 4-17 years who failed ≥1 biologic or methotrexate received weight-tiered (< 75 kg: 10 mg/kg; 75-100 kg: 750 mg; > 100 kg: 1000 mg) intravenous abatacept at Weeks 0, 2, 4, and every 4 weeks thereafter. The study comprised a short-term period (16 weeks) and ongoing long-term period. Primary endpoint: Week 16 JIA-American College of Rheumatology criteria 30 (JIA-ACR30) response rate. Secondary endpoints/outcomes included Week 16 JIA-ACR50/70/90 response and inactive disease rates, Childhood Health Assessment Questionnaire-Disability Index (CHAQ-DI), pharmacokinetics, safety, and immunogenicity. Proportions of patients achieving Juvenile Arthritis Disease Activity Score in 27 joints using C-reactive protein (JADAS27-CRP) remission (score < 1) and minimal disease activity (MDA; score < 3.8), were among exploratory endpoints. RESULTS: All 20 patients who received study medication completed the short-term period. During the long-term period, two patients discontinued due to insufficient efficacy or patient decision. Median age and disease duration at baseline were 10.5 and 0.75 years, respectively. Week 16 JIA-ACR30 response rate (primary endpoint) was 90.0% (18/20). JIA-ACR50/70/90 response and inactive disease rates at Week 16 were 75.0% (15/20), 70.0% (14/20), 35.0% (7/20), and 25.0% (5/20), respectively. At Week 52, JIA-ACR30/50/70/90 response and inactive disease rates were observed by 88.9% (16/18), 88.9% (16/18), 83.3% (15/18), 66.7% (12/18) and 44.4% (8/18), respectively. CHAQ-DI improved after Week 12. JADAS27-CRP remission and MDA were achieved by 15.0% (3/20) and 45.0% (9/20) of patients at Week 16, and by 50.0% (9/18) and 78.0% (14/18) of patients at Week 52, respectively. The mean abatacept pre-dose serum concentration was above the target therapeutic exposure (10 µg/ml) from Week 8 through Week 16. All adverse events were of mild/moderate intensity, except for one case of severe gastroenteritis. No deaths, malignancies, or autoimmune disorders were observed. No antidrug antibodies were detected through Week 16; one patient had a positive immunogenic response during the cumulative period. CONCLUSION: Intravenous abatacept was efficacious and well tolerated in Japanese patients with active pJIA. TRIAL REGISTRATION: ClinicalTrials.gov: NCT01835470 . Date of registration: April 19, 2013.

Early prediction for over two years efficacy of the first biologic agent for polyarticular juvenile idiopathic arthritis: A multi-institutional study in Japan.

OBJECTIVE: To estimate target of treatment for long-term efficacy of the first biologic agent used to treat polyarticular juvenile idiopathic arthritis (pJIA). METHODS: A retrospective cohort of patients with pJIA treated at six medical institutions in Japan between 1 March 2005 and 31 October 2014 was identified. The patients were divided by 2-year treatment periods with the first biologic agent into continuous treatment group and switching group. Three markers were examined: matrix metalloproteinase-3 (MMP-3), erythrocyte sedimentation rate (ESR), and disease activity score (DAS) 28-ESR. RESULTS: Thirty-two pJIA patients (8 boys, 24 girls) from 43 recruited patients were included in this study. The treatment periods with the first biologic agent in continuous treatment group (24 patients, 75%) was 40 months (median, range 24-119) and switching group (8 patients; 25%) was 9.5 months (median, 6-18). Markers [odds ratio (95% confidence interval)] at 3 months were MMP-3 [1.02 (0.99-1.05), p = .219], ESR [1.00 (0.78-1.30), p = .998], and DAS28-ESR [13.9 (2.08-409.82), p = .035]. The cut-off point for DAS28-ESR at 3 months to distinguish the two groups was 2.49 (sensitivity, 87.5%; specificity, 87.5%). CONCLUSION: DAS28-ESR of 2.49 at 3 months after initiating the first biologic agent can be a target of sustained treatment in pJIA patients.

A case report of cutaneous polyarteritis nodosa in siblings.

Cutaneous polyarteritis nodosa (CPAN) is characterized by a necrotizing vasculitis of small and medium-sized arteries in the skin, which can be associated with fever, arthralgia, myalgia, and neuropathy, but, unlike polyarteritis nodosa (PAN), there is no visceral involvement. CPAN is rare in childhood. We report two siblings who developed CPAN during childhood. Interestingly, both had Mediterranean fever gene (MEFV) mutation, i.e. heterozygous E148Q. They also shared HLA-A24, -DR15 alleles. Simultaneous occurrence of MEFV mutation and HLA alleles with CPAN has never been reported in Japan. These cases could provide some hereditary clue for the development of CPAN.

A national survey on current use of mycophenolate mofetil for childhood-onset systemic lupus erythematosus in Japan.

PURPOSE: To conduct a national survey of systemic lupus erythematosus (SLE) patients treated with mycophenolate mofetil (MMF). Based on current information on the use of MMF, we aimed to evaluate its efficacy and safety for childhood-onset (c-) SLE. TARGET: We evaluated 115 patients by questionnaire on MMF use for c-SLE in medical facilities specializing in pediatric rheumatic and renal diseases. RESULTS: Average age at SLE onset was 10.6 (range, 2-15) years; average age at the time of starting MMF was 12.3 (range, 2-15) years. Average dose per body surface area was 1,059.3 mg/m(2)/day. Corticosteroid dosing was 20.9 mg/day before treatment but 7.7 mg/day after treatment. Laboratory values before and after MMF treatment were as follows: C3 increased from 67.0 to 84.9 mg/dl (p < 0.001), C4 increased from 10.2 to 15.1 mg/dl (p < 0.001), and anti-DNA antibody decreased from 154.2 to 18.4 IU/ml (p < 0.001). 24 adverse events in 21 cases were reported, but MMF was not discontinued in any. CONCLUSIONS: The amount of MMF for c-SLE in Japan is similar to the standard dose in other countries. Reduction of corticosteroid dose and improvement of laboratory values represent efficacy of MMF. The side effects recorded here indicated tolerability of the drug.

Mycophenolate mofetil as maintenance therapy for childhood-onset systemic lupus erythematosus patients with severe lupus nephritis.

OBJECTIVES: We evaluated histological changes occurring in renal biopsy specimens, between the time before initial induction therapy and after 12 months' maintenance therapy, as well as changes in laboratory parameters, SLE disease activity (SLEDAI), and dosage of corticosteroid (CS) in childhood-onset systemic lupus erythematosus (SLE) patients treated with mycophenolate mofetil (MMF). METHODS: A retrospective analysis was performed on nine patients diagnosed with childhood-onset SLE and lupus nephritis. They were treated with pulsed mPSL and intravenous cyclophosphamide as induction therapy and MMF (500-1500 mg/day) plus CS as maintenance therapy. Renal biopsy was performed before the initial induction therapy and after 12 months' maintenance therapy. RESULTS: Pathological findings at second biopsy were improved in eight of nine patients (89%). The findings of SLEDAI, urinalysis, and blood tests also showed improvement. CS doses could be tapered satisfactorily. Adverse events were observed in two patients. No patients treated with MMF experienced any disease flares during maintenance therapy. CONCLUSIONS: MMF as maintenance therapy might be useful in that not only the histological findings of lupus nephritis were improved, but also CS doses could be beneficially tapered. Nonetheless, this is a retrospective report of only nine cases and further prospective multicenter studies are necessary.

Serum levels of anti-SRP54 antibodies reflect disease activity of necrotizing myopathy in a child treated effectively with combinatorial methylprednisolone pulses and plasma exchanges followed by intravenous cyclophosphamide.

We describe the effectiveness of combinatorial therapy with plasma exchanges and methylprednisolone pulses followed by intravenous cyclophosphamide in a young girl with anti-signal recognition particle 54 (SRP54) antibody-associated myopathy. We also use a newly described quantitative assay to demonstrate the close association between the titers of anti-SRP54 antibodies and disease activity. This is the first report of a pediatric patient indicating that the serum levels of anti-SRP54 antibodies are also beneficial for monitoring the disease activity of progressive necrotizing myopathy.

[Chronic recurrent multifocal osteomyelitis with interstitial myositis].

Chronic recurrent multifocal osteomyelitis (CRMO) is an inflammatory, non-infectious disorder of skeletal system mainly seen in children. We report a case of CRMO presenting with fever and leg pain. The patient was an 11-year-old boy complaining of a fever, swelling and pain on his right foot, and pain on both legs. Although serum levels of CK and aldolase were not increased, MRI imaging suggested polymyositis. Muscle biopsy showed interstitial infiltration of inflammatory cells without any evidences of dermatomyositis or polymyositis. One month later, he complained of a swelling, pain and redness of his left clavicle as recurrently experienced during the recent 6 months, and MRI investigation indicated the diagnosis of osteomyelitis. Bone biopsy was performed and showed chronic inflammatory changes with negative bacterial culture. Multiple bone lesions and muscle uptake of FDG in his legs were revealed by whole body FDG-PET/CT, and he was diagnosed as having CRMO with interstitial myositis. The combinatorial administration of non-steroidal anti-inflammatory drugs and bisphosphonate successfully improved his clinical symptoms and laboratory abnormalities. To our knowledge, there is no report of a patient of CRMO associated with interstitial myositis.

Guidance on the use of canakinumab in patients with cryopyrin-associated periodic syndrome in Japan.

Cryopyrin-associated periodic syndrome (CAPS) is an orphan disease with incidence of about one in 1,000,000 persons. This autoinflammatory disease develops in the neonatal period or early childhood, with various inflammatory symptoms occurring repeatedly throughout the patient's lifetime. It is caused by abnormality of the NLRP3 protein which mediates the intracellular signal transduction mechanism of inflammatory processes, resulting in continuous overproduction of interleukin (IL)-1ß, which induces chronic inflammation and progressive tissue damage. Definitive diagnosis of CAPS is difficult, and treatment has also been difficult because of a lack of effective medications in Japan. Clinical studies of human anti-human IL-1ß monoclonal antibody (canakinumab) treatment were conducted in Japan, and approval was granted for therapeutic use of canakinumab for CAPS in September 2011. Similar to other biological drugs, canakinumab is clinically highly effective. However, sufficient attention to the method of use and adverse drug reactions is necessary. This guidance describes the use of canakinumab in Japan for CAPS in relation to exclusion criteria, method of use, evaluation criteria, and adverse drug reactions.

[A case of acute lymphotic leukemia which was difficult to make a diagnosis of CRMO for moving arthralgia and periarticular swelling].

A girl, 7 years of age, was reported who had been suffered from migratory arthralgia, bone pain and erythematous rash. She had increased inflammatory markers such as C-reactive protein, erythrocyte sedimentation rate, and mild anemia for more than 6 months. In the beginning, she was suspected of having either juvenile idiopathic arthritis or chronic recurrent multifocal osteomyelitis. However, after about 6 months, there were abrupt increases of LDH in serum titers and blast cells were also revealed by bone marrow examination. Upon these findings, she was diagnosed with acute lymphocytic leukemia. Since bone pain and arthralgia bone pain and arthralgia are both indicative of numerous inflammatory disorders such as infectious myelitis, juvenile chronic arthritis, childhood leukemia and malignancies, and auto-inflammatory bone diseases, especially chronic recurrent multifocal osteomyelitis, it is difficult to accurately diagnose right away. For now, these aforementioned inflammatory responses are the sole key findings for clinical investigations. Other than that, there are not enough reports yet to help diagnose incases similar to this. Therefore, it is difficult to differentiate between the disorders above even after blood tests, Ga-scincigraphy, and imaging examinations. Moreover, in the case of childhood leukemia, it was difficult to differentiate these diseases by routine X-ray surveys in the general pediatric fields. The reasons are because there are only a few descriptions on X-ray bone examinations on findings of X-ray bone investigations, and both are usually non-specific. However, according to the pediatric radiology specialists, of which there are only a few in Japan, the imaging results show somewhat abnormal findings could be spotted from the early stage. Through this present case, it is suggested to us that it is important to consult the pediatric radiology specialists in order to speed up the diagnostic process. Furthermore, the accumulation of radiological findings of leukemia in children with bone pain and arthralgia will attribute to an early diagnosis and lead to the resolution of pathogenesis of leukemia.

A pediatric patient with myopathy associated with antibodies to a signal recognition particle.

We report the case of a 15-year-old Japanese girl with myopathy associated with antibodies to a signal recognition particle (anti-SRP myopathy). The patient presented with progressive symmetrical proximal muscle weakness that caused difficulty in walking within 3 months, and marked elevation of the serum creatine kinase levels. A skeletal muscle biopsy revealed active necrotic and regenerating processes, with mild inflammatory changes. Based on the above findings, the patient was diagnosed as having anti-SRP myopathy. Only a limited number of pediatric patients with anti-SRP myopathy has been reported previously, with usually a poor prognosis. Early diagnosis is important for obtaining a better prognosis in patients with anti-SRP myopathy.

[Febrile responses in patients with pediatric rheumatic diseases].

Fever is one of the critical symptoms of patients in pediatrics field. It indicates inflammatory focus somewhere in the body, and the major causes of fever are infectious diseases. Recent progresses of our knowledge about autoinflammatory syndrome promoted the investigation of the mechanism of fever, and suggested that the pro-inflammatory cytokines are the direct causative agents of fever. The basic science revealed that cooperation of IL-6 and IL-1ß induces febrile response. Fever of unknown origin (FUO) remains a challenging problem. Rheumatic diseases, rare infectious diseases, and benign tumors and malignancies are diagnoses to be differentiated. FDG-PET is recently proved a valuable tool for the identification of the etiology in patients with FUO. Since the introduction of biological response modifiers into the treatment of patients with pediatric rheumatic diseases has shifted the therapeutic paradigm, a new concept that the blockade of a unique pro-inflammatory cytokine brings cessation of whole inflammatory responses affected tremendously the clinical medicine. A more investigation of inflammation and its pathophisiology will be needed in pediatric rheumatology.