Xiaoxiao Wang

Understanding the complex epidemiological and virological characteristics of influenza is critical for optimizing seasonal influenza control and prevention programs; to this end, we analyzed the influenza and influenza-like illness (ILI) cases reported in Zhejiang Province from 2010 to 2025. Annual average percentage (AAP) approach was used to estimate the influenza seasonal epidemic onset and duration. Generalized additive model (GAM) was used to explore the nonlinear relationship between age and the positive rate of influenza. Spearman correlation analysis was performed to assess the association between weekly ILI% and influenza positivity rate. A total of 5,853,160 influenza cases and 8,732,124 ILI cases were reported. The ILI% ranged from 2.49 to 6.84% (mean: 4.37%), with the lowest level in 2010-2011 and the highest in 2023-2024. The median duration of seasonal influenza epidemics was 4.59 months (IQR: 2.84-5.88). Children aged 5~14 y had the highest influenza positivity rate (41.73%). Influenza virus subtypes/lineages varied significantly by seasons and age groups. A/H3N2 was the predominant pathogen during the summer seasons and the positivity rate of A/H3N2 was much higher than that of other subtypes/lineages among individuals aged ≤60 y. ILI% was positively correlated with influenza positivity during 2010-2025 except in the 2020-2021 surveillance year. This study revealed significant variations in seasonal epidemic period and age-specific distributions across influenza subtypes/lineages, as well as a marked disruption of influenza activity due to the COVID-19 pandemic.

Background: Babesia , an intraerythrocytic protozoan, is globally distributed and poses a significant public health burden. In China, human babesiosis is mainly caused by Babesia microti , and the Zhejiang Province is endemic. This study aimed to determine the prevalence of B. microti in the population, reservoir hosts, and vectors; assess population exposure risks; and gain further insight into the genotype structure in Zhejiang. Methods: From May 2020 to October 2023, blood samples from local residents and blood donors, as well as blood or liver tissues from rodents and questing or host-attached ticks, were collected from seven counties in southern Zhejiang Province. DNA was extracted for the detection of B. microti and identification of the rodent and tick species. A retrospective investigation was conducted on individuals who tested positive. Positive samples were sequenced for phylogenetic analyses. Results: In total, 4,728 samples were collected, including 2,475 local residents, 358 blood donors, 1,615 rodents, and 280 questing or host-attached ticks. B. microti was detected in six local residents, 71 rodents, and nine ticks, with infection rates of 0.24, 4.40, and 3.21%, respectively. Human infections and positive ticks were found in specific counties, whereas positive rodents were detected in all counties. All six infected individuals were asymptomatic carriers with a history of outdoor activities in forested areas, and four also reported contact with animals. A total of 17 rodent species were identified, among which Niviventer lotipes exhibited the highest risk. The tick species identified included Haemaphysalis longicornis , Ixodes granulatus , Rhipicephalus haemaphysaloides , and Rhipicephalus microplus . Positive samples were detected for both I. granulatus and R. microplus . Sequencing and phylogenetic analyses of the positive samples revealed that all the sequences belonged to the Kobe type. Conclusion: This study is the first comprehensive report of B. microti infection across its life cycle in Zhejiang Province, revealing a wide prevalence in rodents and ticks. Asymptomatic infections in humans have also been reported. N. lotipes appears to be the predominant rodent reservoir host. In addition, I. granulatus and R. microplus may serve as primary tick vectors. These findings provide valuable information for developing preventive strategies against babesiosis in China.

Toxoplasmagondii is a zoonotic parasite infecting approximately one-third of blood donors worldwide; hence, a better understanding of the prevalence of and associated risk factors for T. gondii infection among blood donors is necessary. This study, therefore, aimed to elucidate the infection risk in Zhejiang Province, China via cross-sectional investigation combined with a case-control design. Blood samples were collected from 1807 blood donors for the cross-sectional survey between January 2023 and December 2024 in Zhejiang, eastern China. Enzyme-linked immunosorbent assay and quantitative polymerase chain reaction were used to investigate the prevalence of T. gondii. Questionnaires were used to collect demographic information. In total, 40 seropositive and 40 seronegative participants were selected for risk factor investigation. Univariate and multivariate logistic regression analyses were conducted. The overall prevalence of anti-T. gondii antibodies was 5.9% (95% confidence interval [CI]: 4.9–7.1%), with 100, one, and six participants found to be IgG-positive only (5.5%, 95% CI: 4.5–6.7%), IgM-positive only (0.1%, 95% CI: 0–0.4%), and IgG- and IgM-positive, respectively (0.3%, 95% CI: 0.1–0.8%). All samples were negative for T. gondii as per polymerase chain reaction test results. T. gondii seroprevalence exhibited an age-dependent increase from 2.4% (18–29 years) to 8.2% (50–59 years). Age and occupational distribution patterns varied between eastern and southern regions. Univariate analysis revealed that occupation was a risk factor for T. gondii infection. Repeated blood donation (P = 0.044, OR = 0.243, 95%CI: 0.061–0.964) was negatively associated with T. gondii infection. Multivariate logistic regression demonstrated that age (P = 0.031) and first-time donors (P = 0.011) were significantly associated with higher prevalence rates. Strategies for prevention of transfusion-transmitted toxoplasmosis should be targeted to older and first-time donors. This study provides evidence-based insights to guide prevention strategies and ensure blood safety.

Pinworm infection, caused by Enterobius vermicularis, is highly prevalent in humans, with children being particularly susceptible. This cross-sectional study (2022-2024) investigated the epidemiology and risk factors of E. vermicularis infection among 1179 rural schoolchildren (3-9 years) across four districts in Zhejiang Province. In each district, two kindergartens and two primary schools were selected using simple random sampling. Pinworm infection was identified using adhesive cellophane tape perianal swabbing method. Data on demographics, hygiene habits, and school environment were collected through structured questionnaires. Simple logistic regression analysis was performed for each potential risk factor, and those variables with a P value less than 0.1 were selected for the multivariate logistic regression analysis. The overall infection rate was 4.07%, with the highest prevalence in Xinchang (9.79%), followed by Daishan (2.68%), Wucheng (2.44%), and Yongkang (1.64%). The positive rate among girls was higher than that of boys (5.41% vs. 2.81%, P = 0.020). Among girls, older subjects had a notably higher infection rate compared to younger ones (8.08% vs. 3.19%). Besides, the infection rate of primary school subjects was higher than that of kindergarten subjects (7.48% vs. 3.23%). No significant differences were found in the boys' group. Furthermore, weekly classroom disinfection and monthly health education were associated with lower infection rates. This study underscores the prevalence of E. vermicularis infection in rural schoolchildren in Zhejiang Province and identifies significant risk factors. Strengthening hygiene education and sanitation practices, particularly targeting female students, may serve as effective measures against E. vermicularis infection.

Objectives: The widespread occurrence of anti-malarial drug resistance threatens the current efforts to control malaria in African regions. Molecular marker surveillance helps to track the emergence and spread of drug-resistant malaria cases.Methods: A total of 237 Plasmodium falciparum infections imported from central Africa to Zhejiang Province, China, between 2016 and 2021, were investigated. Genomic DNA was extracted from blood samples of each patient and nested PCRs was used to detect molecular markers in k13, Pfcrt, and Pfmdr1 genes. The spatial and temporal distributions of the molecular markers were analyzed.Results: A limited polymorphism of k13 was observed, including two nonsynonymous (D464E and K503E) and five synonymous mutations. Wild-type CVMNK of Pfcrt predominated (78.5%), whereas 19.5% of the samples harbored the mutant haplotype, CVIET. The point mutation Y184F and the single mutant haplotype NF of Pfmdr1 were the most frequently observed. The geographical distributions of the Pfcrt and Pfmdr1 haplotypes displayed distinct patterns, with the mutant haplotype of Pfcrt more common in Gabon (53.9%) and Congo (50.0%), and wild haplotypes of Pfmdr1 more frequently found in Cameroon, Angola, and Congo. The prevalence of wild-type CVMNK of Pfcrt increased from 68.5–74.6% in 2016–2017 to 81.8–87.5% in 2018–2021. The proportion of wild-type Pfmdr1 also increased from 27.1% in 2016 to 38.5% in 2019.Conclusion: The geographical and temporal distribution of k13, Pfcrt, and Pfmdr1 polymorphisms in P. falciparum parasites imported from central Africa between 2016 and 2021 are demonstrated. Our data provide updated evidence that can be used to adjust anti-malarial drug policies in central Africa and China.

Countries in the Greater Mekong Subregion have committed to eliminate Plasmodium falciparum malaria by 2025. Subclinical malaria infections that can be detected by highly sensitive polymerase chain reaction (PCR) testing in asymptomatic individuals represent a potential impediment to this goal, although the extent to which these low-density infections contribute to transmission is unclear. To understand the temporal dynamics of subclinical malaria in this setting, a cohort of 2,705 participants from three epidemiologically distinct regions of Myanmar was screened for subclinical P. falciparum and P. vivax infection using ultrasensitive PCR (usPCR). Standard rapid diagnostic tests (RDTs) for P. falciparum were also performed. Individuals who tested positive for malaria by usPCR were followed for up to 12 weeks. Regression analysis was performed to estimate whether the baseline prevalence of infection and the count of repeated positive tests were associated with demographic, behavioral, and clinical factors. At enrollment, the prevalence of subclinical malaria infection measured by usPCR was 7.7% (1.5% P. falciparum monoinfection, 0.3% mixed P. falciparum and P. vivax, and 6.0% P. vivax monoinfection), while P. falciparum prevalence measured by RDT was just 0.2%. Prevalence varied by geography and was higher among older people and in those with outdoor exposure and travel. No difference was observed in either the prevalence or count of subclinical infection by time of year, indicating that even in low-endemicity areas, a reservoir of subclinical infection persists year-round. If low-density infections are shown to represent a significant source of transmission, identification of high-risk groups and locations may aid elimination efforts.

Background: Plasmodium vivax is the most widely distributed malaria parasite, and its drug resistance poses unique challenges to malaria elimination. The Greater Mekong Subregion (GMS) is known as the global epicenter of multidrug resistance. Surveillance of molecular markers associated with drug resistance in this area will help to inform drug policy. Methods: Dry blood spots from 58 patients out of 109 with P. vivax infection between 2017, December and 2019, March were obtained from Yingjiang County, Yunnan Province, along the China–Myanmar border. Pvdhfr, Pvdhps, Pvmdr1 and Pvcrt-o were amplified and sequenced to assess gene mutations. The polymorphism and prevalence of these molecular markers were analyzed. Results: Mutations in Pvdhfr at codons 57, 58, 61, 99 and 117 were detected in 27.59, 48.28, 27.59, 32.76 and 48.28% of the isolates, respectively. Single mutant haplotype (I₁₃F₅₇S₅₈T₆₁S₉₉S₁₁₇I₁₇₃) was the most frequent (29.31%, 17/58), followed by double mutant haplotype (20.69%, 12/58). Of three types of tandem repeat variations of Pvdhfr, deletion type was the most common. Pvdhps showed a lower prevalence among mutation genotypes. Single mutant was dominant and accounted for 34.48% (20/58). Prevalence of Pvmdr1 mutations at codons 958 and 1076 were 100.00% and 84.48%, respectively. The proportion of double and single mutant types was 84.48% (49/58) and 15.52% (9/58), respectively. Eleven samples (18.97%, 11/58) showed K10 “AAG” insertion in chloroquine resistance transporter gene Pvcrt-o. Conclusions: There was moderate diversity of molecular patterns of resistance markers of Pvdhfr, Pvdhps, Pvmdr1 and Pvcrt-o in imported P. vivax cases to Yingjiang county in Western Yunnan, along the China–Myanmar border. Prevalence and molecular pattern of candidate drug resistance markers Pvdhfr, Pvdhps, Pvmdr1 and Pvcrt-o were demonstrated in this current study, which would help to update drug policy.