Neonatal varicella is uncommon but may lead to severe complications, including central nervous system involvement. Cerebrospinal fluid findings may be misleading in neonates, and polymerase chain reaction-confirmed viral central nervous system infection may occur without pleocytosis, particularly when lumbar puncture is performed early in the course of illness. We report a 17-day-old term male neonate admitted with generalized vesicular rash and fever associated with irritability and poor feeding. Lumbar puncture performed on admission showed normal cerebrospinal fluid parameters without pleocytosis; however, a multiplex cerebrospinal fluid polymerase chain reaction panel was positive for varicella-zoster virus, and vesicular lesion polymerase chain reaction confirmed varicella-zoster virus infection. The neonate received intravenous acyclovir for 21 days with complete clinical recovery and normal follow-up. This case highlights that a normal cerebrospinal fluid cell count does not exclude neonatal viral central nervous system infection and supports early cerebrospinal fluid polymerase chain reaction testing to confirm varicella-zoster virus central nervous system involvement while rapidly excluding major differentials such as neonatal herpes simplex virus infection.

Intravenous immunoglobulin (IVIg) is the standard of care for the treatment of Kawasaki disease (KD) and should be administered within 10 days of the onset of fever. Management guidelines for children with KD who defervesce spontaneously are not clear. In this study, we analysed patients with KD diagnosed between 1994 and 2024 at our centre who had defervesced spontaneously, had normal acute-phase reactants, and underwent echocardiographic examination, and in whom IVIg had not been administered. We reviewed the records of patients with KD from January 1994 - December 2024. The diagnosis of KD was based on standard guidelines. Patients with KD were said to be in spontaneous defervescence when they remained afebrile for ≥ 48 h, had normal acute-phase reactants [C-reactive protein (CRP), Erythrocyte sedimentation rate (ESR)] and no coronary artery abnormalities (CAAs) on echocardiography at presentation, and when IVIg was not administered. Patients with spontaneous defervescence were subdivided into (i) early defervescence (Ed-KD), if the interval between onset of symptoms and defervescence was < 10 days, and (ii) late defervescence (Ld-KD), if the duration between onset of symptoms and defervescence was ≥ 10 days, respectively. Details of the clinical profile, laboratory investigations, and echocardiography findings were obtained from the records. Of the 1499 patients with KD enrolled during the study period, 115 patients (7.7%; 86 boys) defervesced spontaneously. The median age at disease onset was 6 years (mean, 5.6 years; range, 0.8-15 years). The median duration of fever, defined as the total duration of the febrile episode before spontaneous defervescence, was 5 days (range, 1-21 days). The median interval between illness onset (defined as fever onset) and diagnosis of KD was 15 days (range, 4-40 days), indicating that diagnosis was often made after fever had already subsided. The most common clinical feature was periungual desquamation, followed by rash, oral-mucosal changes, cervical lymphadenopathy, and conjunctival injection. Incomplete presentation was noted in 73.9% (n = 85/115) of patients. No patient has developed CAAs or other cardiac sequelae over a median follow-up of 9 months (range 2 months-156 months). The cumulative follow-up for the cohort was 235 patient-years. The 'low-risk' subgroup of patients with KD who defervesce spontaneously, and have normal acute phase reactants with no CAAs at presentation, have good clinical and coronary outcomes.

Patient is an HLA-B*57:01 positive, 43-year-old male with a history of diabetes type II and admission 10 weeks ago at another institution for pubic symphysis osteomyelitis and associated pseudomonas. Cefepime IV was started and the patient presented with fevers, aches, agranulocytosis, thrombocytopenia and rash as a suspected side effect of cefepime after 3 weeks of treatment. Cefepime was replaced with piperacillin-tazobactam and symptoms resolved. Question to be resolved is whether an HLA-B*57:01 positive, abacavir sensitive patient could have an agranulocytosis cross reaction to cefepime.

Generalized pustular psoriasis (GPP) in infancy is uncommon and is often precipitated by infection, drugs, or systemic inflammatory responses. Although viral illnesses such as influenza have been reported to trigger GPP, acute exacerbation secondary to respiratory syncytial virus (RSV) is rarely described. We report a case of a 2-year-old girl with a prior history of mild psoriasis who developed widespread sterile, small pustules several days after onset of RSV infection symptoms (cough and low-grade fever), consistent with an RSV-associated acute exacerbation of GPP. Laboratory testing was positive for RSV nucleic acid and showed markedly elevated inflammatory markers. The family denied any use of over-the-counter medications prior to rash onset; based on the timing of lesion appearance and characteristic histopathology on skin biopsy (subcorneal pustules, Kogoj pustules, and psoriasiform epidermal hyperplasia), acute generalized exanthematous pustulosis (AGEP) was excluded. Treatment and follow-up: the patient received oral acitretin combined with intravenous immunoglobulin and albumin, after which the cutaneous lesions resolved rapidly. At 1-month post-discharge follow-up, the condition remained stable without recurrence. RSV infection should be recognized as a potential trigger for acute exacerbation of GPP in young children. In febrile acute pustular eruptions, viral nucleic acid testing and histopathological examination are important to enable early, targeted intervention.

The chikungunya virus (CHIKV) is a serious global health concern that is transmitted by Aedes mosquitoes and causes fever, rash, headaches, arthralgia, and fatigue. In 2024, there were approximately 620 000 cases reported and 213 fatalities across the world. In February, Vimkunya (PXVX0317), a virus-like particle vaccine, which is safer than the live-attenuated IXCHIQ vaccine, was approved by the FDA. The Vimkunya has recombinant structural proteins that induce strong neutralizing antibody responses without allowing the virus to replicate. Clinical trials have demonstrated immunogenicity, with a seroresponse rate of ≥87% in older adults and 98% in younger individuals. There were only mild to moderate adverse effects, like headaches, muscle pain, and pain at the injection site, were reported. Vimkunya is a potential approach to lessen the impact of chikungunya and prevent recurrent outbreaks. It has proven to be effective in all age groups, elicits a sustained immune response, and has demonstrated a safer profile in trials. Strategies for fair distribution and ongoing monitoring will be essential for the impact on public health.

Parechovirus A (PeV-A) is a significant cause of sepsis-like illnesses in neonates and infants. Although PeV-A3 has a known association with severe diseases, severe cases of PeV-A5 infection have recently been reported. We present herein a case of PeV-A5 infection in a 23-day-old neonate who presented with sepsis-like symptoms, including fever, irritability, abdominal distension, and a reticular rash. An erythematous rash developed and spread from the trunk to the extremities after the patient's admission. Blood cultures were negative, and the patient's symptoms rapidly improved with supportive therapy. Polymerase chain reaction testing of pharyngeal and rectal swabs confirmed PeV-A5 infection, as well as the presence of PeV-A5 in the serum during the acute phase. PeV-A5 RNA was undetectable in serum at follow-up testing, whereas stool specimens showed higher detection sensitivity, indicating that the time from symptom onset and specimen selection influence diagnostic accuracy. Whole-genome analysis suggested a recombinant PeV-A5 strain with structural protein regions similar to those of PeV-A5 and nonstructural regions similar to those of PeV-A3. This genomic feature may explain the patient's clinical presentation resembling that of a PeV-A3 infection. PeV-A5 may cause sepsis-like symptoms in early infancy, the pathogenicity of which may be affected by genetic recombination. Further case studies are required to elucidate the clinical features and pathogenicity of PeV-A5 infection.

The clinical differentiation of Chikungunya from other acute febrile illnesses poses a significant diagnostic challenge due to the substantial symptom overlap among co-circulating arboviruses such as Dengue and Zika, particularly in resource-constrained settings where laboratory confirmation is frequently delayed or unavailable. This study proposes an interpretable machine learning framework for the prediction of laboratory-confirmed Chikungunya cases versus suspected cases that were subsequently discarded after laboratory investigation, using a large-scale, nationally representative dataset of 12,709 notification records derived from Brazil's Information System for Notifiable Diseases (SINAN), spanning 2013 to 2020 and encompassing 26 clinical symptom, comorbidity, and sociodemographic features. Four supervised learning algorithms-Logistic Regression, Random Forest, XGBoost, and LightGBM-were systematically evaluated under 5-fold stratified cross-validation, with Random Forest achieving the highest discriminative performance (AUC = 0.785 ± 0.005) and XGBoost demonstrating the best probability calibration reliability. Considering the trade-off between discrimination and calibration, XGBoost was identified as the most suitable model for potential clinical deployment. To ensure clinical transparency, a structured three-level SHapley Additive exPlanations (SHAP) interpretability analysis was conducted on both gradient boosting models, encompassing global feature importance ranking, feature-level directional and interaction effects, and local patient-level prediction decomposition. The SHAP analysis consistently identified arthralgia (mean |SHAP|: 0.7407 in XGBoost, 0.7489 in LightGBM) and fever (0.5043 and 0.4881, respectively) as the two dominant predictors of Chikungunya confirmation, followed by age, education level, and rash, while comorbidities contributed negligibly to case discrimination. Cross-model validation between XGBoost and LightGBM revealed highly concordant feature importance rankings and directional effect patterns, confirming that the identified clinical predictors are robust and independent of algorithmic choice. These findings demonstrate the practical value of combining machine learning with SHAP-based explainability for supporting clinical triage of suspected arboviral cases, providing a transparent, evidence-based diagnostic support tool that aligns data-driven insights with established clinical knowledge and enables personalized patient-level explanations at the point of care. Importantly, the model distinguishes confirmed Chikungunya from discarded suspected cases rather than from confirmed infections with other specific arboviruses, and its predictions should be interpreted within this operational context.