Objective:To evaluate the application of metagenomic next-generation sequencing（mNGS）in the identification of non-tuberculous mycobacteria（NTM）.Methods:A retrospective analysis was conducted on mNGS results of 358 bronchoalveolar lavage fluid（BALF）samples positive for NTM collected at the First Affiliated Hospital of Zhejiang University School of Medicine from February 2021 to January 2024. The analysis included the distribution of NTM species，the detection of mixed pathogens，and the performance of conventional mycobacterial detection methods.Results:The results showed that 362 strains of 15 NTM species were identified from 350 specimens，8 specimens were not precise to the species level. The most frequently detected species were Mycobacterium intracellulare（37.3%，135/362）， Mycobacterium abscessus（26.8%，97/362），followed by Mycobacterium avium（11.0%，40/362）， Mycobacterium kansasii（8.0%，29/362）and Mycobacterium chelonae（7.7%，28/362）. Single NTM species were detected in 339 specimens，while two or three NTM species were simultaneously detected in 11 specimens（3.1%，11/358）. Non-NTM microorganisms co-infected were detected in 53.4%（191/358）of NTM-positive BALF samples，including common pathogens such as Pseudomonas aeruginosa， Staphylococcus aureus，and Aspergillus fumigatus；and difficult-to-identify pathogens such as Legionella pneumophila and Talaromyces marneffei. In NTM-positive patients detected by mNGS，the results supported the diagnosis of NTM infection in 298 cases（298/358，83.2%）and 105 cases（105/358，29.3%）initiated anti-NTM treatment accordingly；while in 60 cases（60/358，16.8%）the positive results were considered as colonization or unrelated to clinical infection. For samples tested with acid-fast staining，mycobacterial liquid culture，and DNA microarray，the positivity rates for NTM were 31.5%（73/232），48.7%（57/117），and 43.0%（46/107），respectively. Conclusions:mNGS demonstrates advantages in identification of NTM. However，the test may detect multiple microorganisms，in that case，the interpretation with clinical and radiological results is requried to determine the main pathogens.

Objective:To analyze the epidemiological and clinical characteristics of respiratory pathogens in China.Methods:This study was a cross-sectional study, which encompassed 19 core units of the clinical pathogen network and established a three-tiered clinical pathogen surveillance system. Thirty respiratory samples were collected every two weeks from various units from January to December 2024, and the clinical and pathogen diagnostic information were gathered. A total of 11 864 samples were tested using this system. The tier-1 clinical pathogen surveillance system covered influenza A virus (Flu-A), influenza B virus (Flu-B), respiratory syncytial virus (RSV), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The tier-2 clinical pathogen surveillance system focused on 18 key respiratory pathogens. The tier-3 clinical pathogen surveillance system further clarified whether any emerging infectious diseases had occurred.Results:The tier-1 clinical pathogen surveillance system showed Flu-A predominated in December, Flu-B predominated in January, SARS-CoV-2 peaked in March and August, whereas RSV circulated sporadically throughout the year. Geographic trends were broadly consistent across the seven major regions, although Flu-A detection in December was notably higher in Northeast China (48.1%(111/231)) and East China (36.2%(148/409)), and RSV detection was concentrated in the Northwest and South China from January to March. Data from the tier-2 clinical pathogen surveillance system indicated that Streptococcus pneumoniae, Mycoplasma pneumoniae, rhinovirus, and adenovirus were detected year-round, of these, Streptococcus pneumoniae and rhinovirus showed elevated positive detection rates from August to September, while adenovirus peaked in January. Legionella pneumophila was not detected throughout the year, and other pathogens fluctuated throughout the year without a consistent pattern. The predominant etiologic agents of pediatric pneumonia were Mycoplasma pneumoniae (35.0%(105/300)), rhinovirus (25.7%(77/300)), and adenovirus (17.3%(52/300)), whereas adult pneumonia was mainly caused by Streptococcus pneumoniae (10.5%(29/277)), Staphylococcus aureus (6.9%(19/277)), Mycoplasma pneumoniae (6.9%(19/277)), and Flu-A (6.1%(17/277)). The tier-3 clinical pathogen surveillance system did not identify any emerging respiratory pathogens. Conclusion:Respiratory pathogens in China in 2024 exhibit distinct temporal and spatial distribution patterns and vary among different populations.

Objective:To analyze the clinical characteristics, distribution of common pathogenic bacteria and drug resistance in children with non-chronic osteomyelitis, to provide a basis for empirical antimicrobial drug selection.Methods:This study was a retrospective analysis cohort study. Clinical data, pathogenic bacteria and drug sensitivity test results of 289 children aged 0 to 18 years with non-chronic osteomyelitis who were hospitalized in the Pediatrics Hospital of Fudan University from January 2013 to June 2023 were collected retrospectively. Statistical analyses were performed using chi-square test.Results:Of the 289 children, 188(65.1%) were male, with a male to female ratio of 1.86∶1, and the age was 3.00(0.66, 8.00) years. The age less than six years amounted 65.1% (188/289). The incidence was the highest from December to February of the following year, reaching 32.5%(94/289). The clinical manifestations were fever in 193 cases (66.8%), fever with localized pain in 47 cases (16.3%), and fever with localized swelling and fever with localized swelling and pain in 39 cases (13.5%) each. Single bone involvement was observed in 242(83.7%) cases, including 88(36.4%) femur, 47(19.4%) tibia, and 37(15.3%) humerus. Of the 130 pathogen-positive cases, 102(78.5%) were Staphylococcus aureus (SA) including 45(44.1%) methicillin-resistant Staphylococcus aureus (MRSA), 10(7.7%) were Pseudomonas aeruginosa, and 3(2.3%) each were Klebsiella pneumoniae and Staphylococcus mansoni. The rate of MRSA detection in SA fluctuated each year from 2013 to 2023, with the highest in 2017, when eight out of 13 SA cases were MRSA. The resistance rates of all SA to vancomycin, linezolid, moxifloxacin, ciprofloxacin, gentamicin, rifampicin, ceflorin, tigecycline, ticlosporin, fosfomycin, daptomycin, furotoxin, quinupristin/dalfopristin were all zero, and the differences in resistance rates of methicillin-susceptible Staphylococcus aureus (MSSA) and MRSA to cefazolin, cefuroxime, benzoxiline, ampicillin/sulbactam, and clindamycin were all statistically significant ( χ2=68.91, 68.91, 82.00, 68.91 and 9.20, respectively, all P<0.05). Intravenous anti-infective treatment was administered for 24(35, 47) days in 289 children with osteomyelitis, for a total duration of 42.00(35.00, 47.00) days. After treatment, 287 cases (99.3%) were discharged with improvement, while two cases (0.7%) died. One death was due to phagocytosis syndrome and septic shock, and the other death was due to septic shock and multiple organ dysfunction. Conclusions:Non-chronic osteomyelitis in children is most common in male children under six years old, and the most common sites are femur, tibia and humerus. The main clinical manifestations are fever, localized swelling and pain. SA was the most common causative agent. No SA strain resistant to vancomycin, linezolid, moxifloxacin, ciprofloxacin, gentamicin, rifampicin, ceflorin, tigecycline, ticlosporin, fosfomycin, daptomycin, furotoxin, quinupristin/dalfopristin is found.

Objective:To evaluate the efficacy and immunological mechanisms of pegylated interferon α-2b (Peg-IFNα-2b) antiviral therapy in treatment-naive patients with chronic hepatitis B(CHB).Methods:A total of 166 treatment-naive CHB patients, who were treated at Department of Infectious Diseases, the Second Affiliated Hospital of Nanchang University from March 2021 to March 2023, were enrolled in this study. All the patients received Peg-IFNα-2b therapy for 48 weeks. Serum hepatitis B virus (HBV) DNA, HBV serological markers, biochemical parameters, peripheral blood lymphocyte subsets and serum cytokine levels were detected and compared before and after treatment. Chi-square test, Mann-Whitney U test and paired sample t test were used for statistical comparison. Multivariate logistic regression analysis was used to analyze the influencing factors of hepatitis B surface antigen (HBsAg) seroconversion by stepwise regression method, and the receiver operator characteristic curve (ROC curve) was used to evaluate the predictive efficacy of immune indicators on HBsAg seroconversion. Results:Among the 166 treatment-naive CHB patients, the rate of HBV DNA negativity following 48 weeks of Peg-IFNα-2b therapy was 71.08%(118/166), the rate of hepatitis B e antigen (HBeAg) negativity was 32.05%(25/78), and the rate of HBsAg negativity was 20.48%(34/166). HBsAg negativity rate was 52.17%(24/46) in patients with baseline HBsAg<200 IU/mL, 10.26%(4/39) in patients with baseline HBsAg 200 to <1 200 IU/mL, and 7.41%(6/81) in patients with baseline HBsAg≥1 200 IU/mL, and the difference was statistically significant( χ2=39.37, P<0.001). After 48 weeks of treatment, serum levels of alanine transaminase (ALT), aspartate transaminase (AST), total bilirubin (TBil), and alpha-fetoprotein (AFP) were significantly lower than those before treatment ( Z=9.33, 8.58, 5.99, 2.36, respectively, all P<0.05). lmmune indicators were detected in 58 patients, and the proportion of peripheral blood lymphocytes increased significantly post-treatment, with notable increases in CD3 + CD8 + T/CD3 + T, CD3 + CD4 + DR + /CD3 + CD4 + , CD3 + CD8 + DR + /CD3 + CD8 + , CD3 + CD8 + CD38 + /CD3 + CD8 + , CD3 + CD8 + CD28 + /CD3 + CD8 + , and CD19 + B cells, and the differences were all statistically significant ( t=-2.56, t=-8.65, Z=-3.58, t=-3.66, Z=-3.04, t=-3.62, t=-3.87, respectively, all P<0.05). Conversely, the proportion of CD3 + , CD3 + CD4 + T/CD3 + T, CD3 + CD4 + CD45RO + /CD3 + CD4 + , CD3 + CD8 + CD45RO + /CD3 + CD8 + and the CD4 + /CD8 + ratio decreased significantly post-treatment ( t=3.13, t=5.61, t=3.69, Z=3.95, Z=7.33, respectively, all P<0.05). No significant differences were observed in the proportion of CD16 + CD56 + natural killer (NK) cells, CD3 + CD4 + CD28 + /CD3 + CD4 + , CD3 + CD4 + CD38 + /CD3 + CD4 + cells before and after treatment (all P>0.05). Serum levels of interleukin(IL)-8, IL-12P70, and IL-17 significantly decreased post-treatment ( Z=2.85, 3.26, 4.12, respectively, all P<0.05), while IL-2, IL-1β, and interferon(IFN)-α levels were significantly elevated compared to baseline ( Z=-4.92, -4.85, -9.01, respectively, all P<0.001). There were no significant differences in IL-4, IL-6, and IL-10 levels before and after treatment (all P>0.05). Logistic regression analysis identified CD3 + CD8 + T/CD3 + T(odd ratios ( OR)=1.198, 95%confidence interval( CI) 1.003 to 1.432, P=0.046), CD3 + CD4 + DR + /CD3 + CD4 + ( OR=1.185, 95% CI 1.035 to 1.357, P=0.014), CD3 + CD8 + DR + /CD3 + CD8 + ( OR=0.813, 95% CI 0.690 to 0.958, P=0.013), CD3 + CD4 + CD38 + /CD3 + CD4 + ( OR=0.678, 95% CI 0.488 to 0.940, P=0.020), CD3 + CD8 + CD38 + /CD3 + CD8 + ( OR=1.272, 95% CI 1.069 to 1.512, P=0.007), CD19 + B cells( OR=0.752, 95% CI 0.582 to 0.971, P=0.029), IL-2( OR=8.568, 95% CI 1.927 to 38.087, P=0.005), and IL-17( OR=0.728, 95% CI 0.535 to 0.989, P=0.042) as independent factors influencing HBsAg seroconversion. The area under the curve (AUC) of the proportion of dCD19 + B cells (the reciprocal of CD19 + B cells) for predicting HBsAg seroconversion was 0.716, the sensitivity was 0.636, and the specificity was 0.809. The AUC of IL-2 was 0.657, the sensitivity was 0.818, and the specificity was 0.404. The AUC of dIL-17 (the reciprocal of IL-17 levels) was 0.624, the sensitivity was 0.727, and the specificity was 0.489. The AUC of IL-2 and dIL-17 as a combined predictor was 0.830, the sensitivity was 0.909, and the specificity was 0.787. Conclusions:Peg-IFNα-2b demonstrates significant antiviral, biochemical, and serological responses in treatment-naive CHB patients, with enhanced efficacy in patients exhibiting HBsAg levels <200 IU/mL. In patients with HBsAg<200 IU/mL, the rate of HBsAg negativity reached 52.17%.Peg-IFNα-2b can regulate the immune function of patients with CHB by increasing the proportion of activated T lymphocyte subsets and functional subsets. The proportion of CD19 + B cells, IL-2 levels, and IL-17 levels hold predictive value for achieving HBsAg seroconversion.

Objective:To analyze the baseline characteristics and prognostic factors of Pneumocystis carinii pneumonia (PCP) in patients with liver diseases (LD), and to develop the nomogram prognosis model. Methods:The patients with liver diseases complicated with PCP (LD-PCP) who admitted to Beijing Youan Hospital, Capital Medical University from January 1st, 2021 to October 31st, 2024 were enrolled in this study. This study was a retrospective case-control study. Data were collected, including baseline characteristics at admission and clinical outcomes. Multivariate logistic regression analysis was employed to identify the independent risk factors of poor prognosis in LD-PCP patients. Subsequently, a nomogram was developed to construct the prognostic model. The performance of this model was evaluated using the receiver operater characteristic (ROC) curve and calibration curve.Results:A total of 61 patients with LD-PCP were enrolled, including 21 in the death group and 40 in the survival group. Multivariate logistic regression analysis revealed that co-infection with Aspergillus and elevated lactate dehydrogenase (LDH) levels were independent risk factors for mortality in patients with LD-PCP (odds ratio ( OR)=12.802, 95% confidence interval ( CI) 1.334 to 122.845, P=0.027; OR=1.009, 95% CI 1.002 to 1.016, P=0.014). The predictive value of prognostic model based on the nomogram was better evidenced by the ROC curve, which yielded an area under the curve (AUC) of 0.835 (95% CI 0.725 to 0.944), with the sensitivity of 71.4% and the specificity of 87.5%. The predictive accuracy of the model was further validated by the calibration curve, and the Brier value was 0.151, the model fitting line had a high degree of agreement with the standard reference line ( P=0.953). Conclusions:Co-infection with Aspergillus and LDH levels are independent risk factors for the poor prognosis of patients with LD-PCP. The prognosis model based on the nomogram has better predictive value and clinical practicality, which could identify high-risk patients in the early stage, and provide theoretical guidance on the patient management.

Objective:To investigate the risk factors for kidney injury during anti-retroviral therapy (ART) with zidovudine (AZT) or tenofovir disoproxil fumarate (TDF) in human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) patients, and to construct and validate a prediction model for the risk of kidney injury in HIV/AIDS patients based on a nomogram.Methods:A total of 923 HIV/AIDS patients admitted to Liuzhou People′s Hospital between January 1st, 2004 and December 31st, 2020 were included in this study. The modeling set (647 cases) and the validation set (276 cases) were divided in a 7∶3 ratio. Risk factors were screened using the least absolute shrinkage and selection operator (LASSO) regression analysis, and a nomogram prediction model for renal impairment risk in HIV/AIDS patients was constructed based on the selected variables. The model′s predictive performance was assessed by calculating the area under the curve (AUC) using the receiver operating characteristics curve (ROC curve). The performance of this model was evaluated using calibration curves. The clinical utility of the model was assessed using decision curve analysis (DCA).Results:Among 923 HIV/AIDS patients, there were 91 cases with kidney injury, including 67 in the modeling set and 24 in the validation set. AZT was used in 29 cases, and TDF was used in 62 cases. LASSO regression analysis was employed to screen seven non-zero variables, including age, ART regimen, baseline estimated glomerular filtration rate (eGFR), baseline CD4 + T lymphocyte count, baseline human immunodeficiency virus (HIV) RNA, baseline hemoglobin, and baseline aspartate aminotransferase (AST), their LASSO regression coefficient were 1.296, 0.250, 1.443, 0.240, 0.120, 0.395, and 0.002, respectively. Based on these variables, a visual nomogram model was constructed and subsequently validated. Through ROC curve analysis, the AUC for the modeling set was 0.826 (95% confidence interval ( CI) 0.767 to 0.884), with a sensitivity of 0.731 and a specificity of 0.809. For the validation set, the AUC was 0.872 (95% CI 0.807 to 0.956), with a sensitivity of 0.875 and a specificity of 0.778. The calibration curve results for the modeling set showed a mean absolute error (MAE) of 0.012 and a consistency index of 0.826, while the validation set had an MAE of 0.021 and a consistency index of 0.872. These results indicated that the model had a high goodness-of-fit, excellent calibration performance, and was reliable and stable. When the risk threshold for the modeling set ranged from 2% to 73%, the model demonstrated favorable net benefits, indicating its excellent clinical utility. Conclusion:The nomogram-based risk prediction model for kidney injury in HIV/AIDS patients is constructed using seven variables including age, ART regimen, baseline eGFR, baseline CD4 + T lymphocyte count, baseline HIV RNA, baseline hemoglobin, and baseline AST, which provides a valuable tool for early identification of individuals at risk of kidney injury and supports timely clinical interventions.

Objective:To investigate the clinical characteristics, prevalent serum groups, and drug sensitivity test results of epidemic cerebrospinal meningitis in children in Shanghai area.Methods:The study was a retrospective case-control study. The children hospitalized for epidemic cerebrospinal meningitis in Children′s Hospital of Fudan University from January 2003 to December 2023 were enrolled. Clinical data were collected, including demographic characteristics, clinical manifestations, pathogen detection results, strain typing, and drug sensitivity test results.Results:A total of 77 children with confirmed epidemic cerebrospinal meningitis were hospitalized, including 50 males (64.94%) and 27 females (35.06%). The age was 24(8, 60) months, with 16 cases (20.78%) aged 0 to five months, nine cases (11.69%) aged six to 11 months, 21 cases (27.27%) aged 12 to 35 months, 16 cases (20.78%) aged three to five years, 13 cases (16.89%) aged six to 11 years, and two cases (2.60%) aged 12 years. The highest number of cases was in spring, with 36 cases (46.75%), followed by winter with 25 cases (32.47%). Thirty-three cases (42.86%) had vaccinated with meningococcal vaccine. The clinical symptoms included fever in all 77 cases (100.00%), skin petechiae and ecchymosis in 58 cases (75.32%), vomiting in 56 cases (72.73%), respiratory symptoms in 12 cases (15.58%), convulsions in 17 cases (22.08%), conscious disturbance in 24 cases (31.17%), shock in 38 cases (49.35%), circulatory failure in 13 cases (16.88%), and respiratory failure in seven cases (9.09%). Among the 77 children, fifty-seven cases (74.03%) were common type and 20 cases (25.97%) were fulminant type, with seven deaths (9.09%). Neisseria meningitidis (Nm) was detected in 55 cases (71.43%), with the positive rates of skin petechiae smear and cerebrospinal fluid smear of 23.26%(10/43) and 19.44%(14/72), respectively. The positive rates of cerebrospinal fluid culture and blood culture were 36.51%(23/63) and 31.51% (23/73), respectively. The positive rate of polymerase chain reaction detection was 79.17%(38/48). The serogroups were determined in the 38 Nm strains, including 18 cases (47.37%) of group B, 14 cases (36.84%) of group C, five cases (13.16%) of group A, and one case (2.63%) of group Y. Among the 29 Nm strains tested for antimicrobial susceptibility, one strain (3.45%) was resistant to penicillin, two strains (6.90%) were resistant to cefotaxime, 21 strains (72.41%) were resistant to ciprofloxacin, and 25 strains (86.21%) were resistant to sulfamethoxazole/trimethoprim. All strains were sensitive to ceftriaxone, azithromycin, meropenem, rifampicin, chloramphenicol, and minocycline. Conclusions:Epidemic cerebrospinal meningitis presents a low prevalence trend in children in Shanghai area. Infants and toddlers remain the major susceptible individuals. Nm has reduced sensitivity to penicillin, but remains sensitive to ceftriaxone. Ceftriaxone is recommended as the first-line choice for antibiotic therapy. The prevalent serogroups are Group B, Group C, Group A and Group Y in sequence. Immunization plan adjustment should be suggested. Vaccination covering the current epidemic serum population as early as possible should be recommended.

Objective:To investigate the changes of the epidemiology and clinical characteristics of human metapneumovirus (hMPV) among children with acute lower respiratory tract infection (ALRTI) before and after the discontinuation of non-pharmaceutical interventions (NPI) during coronavirus disease 2019 epidemic.Methods:This was a retrospective cohort study. Children hospitalized at The Second Affiliated Hospital and Yuying Children′s Hospital of Wenzhou Medical University between January 2021 and December 2023, who were diagnosed with ALRTI by nasopharyngeal secretion testing for respiratory pathogens nucleic acid were enrolled. Clinical and laboratory data were collected. Children admitted between January 1, 2021 and January 7, 2023 were classified as the pre-NPI withdrawal group (abbreviated as pre-withdrawal group), while those admitted from January 8, 2023 afterward were classified as the post-NPI withdrawal group (abbreviated as post-withdrawal group). Nasopharyngeal secretions from the enrolled children were tested for 13 respiratory pathogens using polymerase chain reaction-capillary electrophoresis fragment analysis, and bacterial cultures were also performed. Statistical analyses were performed using the Mann-Whitney U test or chi-square test. Results:A total of 30 855 ALRTI cases were enrolled, with 1 679 of hMPV-positive. In the pre-withdrawal group, there were 861 cases with an age of onset of 2.0(1.0, 3.0) years, and the highest proportion was in the 1 to <3 years age group, accounting for 35.3%(304/861). In the post-withdrawal group, there were 818 cases with an age of onset of 3.0(2.0, 4.0) years, and the highest proportion was in the 3 to <5 years age group, accounting for 39.2%(321/818).The age of onset in the post-withdrawal group was significantly older than that in the pre-withdrawal group ( Z=7.69, P<0.001) .The hMPV detection rate was higher in the pre-withdrawal group than that in post-withdrawal group (5.75%(861/14 984) vs 5.15%(818/15 871); χ2=5.25, P=0.022). In the pre-withdrawal group, the epidemic peaks occurred in winter and spring, with the highest rates in January 2022(25.2%(224/890)) and March 2022 (21.6%(186/860)). In the post-withdrawal group, the epidemic peak shifted to spring and summer, and the detection rate became increased since April 2023(10.8%(136/1 258)). The post-withdrawal group showed lower rates of wheezing, shortness of breath, cyanosis, respiratory support, severe pneumonia, intensive care unit admission, and shorter hospital stays compared to the pre-withdrawal group ( χ2=69.09, 31.63, 12.97, 57.96, 55.73, 5.48 and Z=7.11, respectively, all P< 0.05).In the pre-withdrawal group, 412 cases (47.9%(412/861)) had other pathogens detected, compared to 445 cases (54.4%(445/181)) in the post-withdrawal group, indicating a significantly higher rate of co-infections in the post-withdrawal group ( χ2=7.20, P<0.05). The most commonly detected pathogens in both groups were Mycoplasma pneumoniae (MP), rhinovirus, and Streptococcus pneumoniae. However, the post-withdrawal group showed significantly higher detection rates of MP and influenza virus, but lower bacterial detection rates compared to the pre-withdrawal group ( χ2=39.41, 9.70, 5.63, respectively, all P<0.05). The detection rate of Haemophilus influenzae was 2.1%(17/818) in the post-withdrawal group which lower than that (6.7%(58/861)) in the pre-withdrawal group, and the difference was statistically significant ( χ2=21.32, P<0.001). Conclusions:In 2023, following the withdrawal of NPI, the epidemic peak of hMPV in Wenzhou area is delayed to spring and summer. The age of children with hMPV-associated ALRTI increases, with the majority being 3 to <5 years old. The overall severity of the disease decreases. However, the detection of mixed pathogens increases, with MP being the most common, while bacterial detection decreases.

Objective:To analyze the clinical characteristics of the Chikungunya fever outbreak in Shunde District, Foshan City, Guangdong Province in July 2025 and the risk factors associated with delayed viral RNA clearance.Methods:A total of 562 patients with Chikungunya fever admitted to three designated hospitals in Shunde District from July 10 to 30, 2025 were enrolled. Demographic data, clinical manifestations, and laboratory findings were collected. Patients were categorized into four age groups including minors (<18 years), young adults (18 to 39 years), middle-aged adults (40 to 64 years) and elderly adults (≥65 years). The differences of clinical characteristics among these age groups were analyzed. Intergroup comparisons were performed using chi-square test, one-way analysis of variance, or Kruskal-Wallis H test. Pairwise comparisons between groups were conducted using the Bonferroni or Games-Howell or Dunn method. Binary logistic regression was employed to analyze risk factors associated with delayed viral RNA clearance (>7 days). Results:The mean age of the 562 enrolled Chikungunya fever patients was (44.8±21.3) years. Fever, arthralgia and rash were the three core symptoms, with incidence rates of 87.5% (492/562), 88.4%(497/562) and 69.6%(391/562), respectively. At discharge, only 54.1%(304/562) of patients achieved complete symptom resolution, while 26.5%(149/562) still had arthralgia and 36.1%(203/562) had residual rash. Significant differences were observed among age groups in the incidence of fever ( χ2=9.43, P=0.024), peak body temperature ( F=6.54, P<0.001), incidence of arthralgia ( χ2=26.89, P<0.001), duration of arthralgia ( F=12.68, P=0.001), incidence of rash ( χ2=68.99, P<0.001), rate of residual rash at discharge ( χ2=32.37, P<0.001), lymphocyte count ( F=12.94, P<0.001), platelet count ( F=14.95, P<0.001), and C-reactive protein levels (CRP) ( H=94.18, P<0.001). Further pairwise comparisons revealed that compared to the middle-aged and elderly groups, the minor group had a higher incidence of fever and a lower incidence of arthralgia, and the duration of arthralgia was shorter than the elderly group (all P<0.008 3). Compared with the other three groups, the elderly group had lower incidence and residual rate of rash, and lower platelet counts (all P<0.008 3), and higher levels of CRP (all P<0.05). The elderly group had lower lymphocyte counts compared to the minor and young adult groups (both P<0.05). Significant differences were found among age groups in the time to viral RNA clearance ( F=5.77, P=0.003) and length of hospital stay ( F=11.64, P<0.001), with the elderly group having significantly longer duration for both compared to the other three groups (all P<0.05). Multivariate analysis showed that advanced age (odds ratio ( OR)=1.049, 95% confidence interval ( CI) 1.015 to 1.083), longer duration of fever ( OR=1.529, 95% CI 1.086 to 2.155) and longer duration of arthralgia ( OR=1.927, 95% CI 1.318 to 2.817) were independent risk factors for delayed viral RNA clearance (all P<0.05). Conclusions:Patients with Chikungunya fever in Shunde District primarily present with fever, arthralgia and rash. The incidence and characteristics of these three core symptoms show age-related variations. Elderly patients and those with longer durations of fever or arthralgia are more likely to experience delayed viral clearance.

Objective:To characterize the epidemiological features of hemorrhagic fever with renal syndrome (HFRS) in Jixi region, Heilongjiang Province, and to develop an autoregressive integrated moving average (ARIMA) model to predict the incidence trend of HFRS, thus to provide a scientific basis for targeted prevention and control.Methods:HFRS case data and host animals surveillance data from January 2013 to December 2024 in Jixi City were collected. Descriptive epidemiological methods were used to analyze the temporal, spatial, and population distribution characteristics of HFRS, with comparisons made using the chi-square test. ArcGIS10.8.2 software was employed for spatial clustering analysis. Moran I was used to assess the overall spatial trend of HFRS incidence. Getis-Ord Gi * analyses was used to identify the hotspots and coldspots. SaTScan v10.2 software was applied to detect spatiotemporal clusters. The Spearman correlation analysis was used to examine the relationship between rodent viral load index and HFRS incidence. ARIMA model was constructed and optimized using Bayesian information criterion (BIC) for short-term prediction of HFRS. Results:From January 2013 to December 2024, a total of 1 045 HFRS cases were reported in Jixi City, with an average annual incidence rate of 5.09/100 000. Three epidemic peaks were observed: 2014 (8.12/100 000), 2019 (7.22/100 000), and 2023 (3.86/100 000). The temporal distribution showed a bimodal pattern, with the autumn-winter peak (October to December) having more cases than the spring-summer peak (May to June). Geographically, cases were mainly concentrated in the central-eastern urban areas of Jixi City. The average annual incidence rate in males (7.89/100 000) was significantly higher than that in females (2.24/100 000), the difference was statistically significant ( χ2=322.15, P<0.001). The highest incidence rate was observed in the 50 to 59 age group (6.79/100 000), and farmers accounted for the largest proportion of cases (59.04% (617/1 045)). Spatial analysis revealed clustered distribution (Moran I=0.50, P<0.05), with hotspots in Hulin City and Mishan City. Spatiotemporal analysis identified one significant cluster (radius=89.2 km). No correlation was found between the rodent viral load index and HFRS incidence ( r=0.455, P=0.138). The optimal short-term prediction model was ARIMA (1, 0, 0) (0, 1, 1) (BIC=-3.24), which forecasted 38 HFRS cases in Jixi City in 2025. Conclusions:HFRS incidence in Jixi City exhibits periodicity, seasonality, and spatial clustering. The developed ARIMA model provides a valuable tool for predicting incidence trends, thus to optimize vaccination, rodent control, and surveillance measures in high-risk areas and populations.