Non-invasive geophysical methods for monitoring the shallow aquifer based on time-lapse electrical resistivity tomography, magnetic resonance sounding, and spontaneous potential methods.

The Ningdong coalfield has played a pivotal role in advancing local economic development and meeting national energy. Nevertheless, mining operations have engendered ecological challenges encompassing subterranean water depletion, land desertification, and ground subsidence, primarily stemming from the disruption of coal seam roof strata. Consequently, the local ecosystem has incurred substantial harm. Water-preserved coal mining presently constitutes the pivotal technology in mitigating this problem. The primary challenge of this technique lies in identifying critical aquifer layers and understanding the heights of water-conducting fracture zones. To obtain a precise comprehension of the seepage patterns within the upper coal seam aquifer during mining, delineate the extent of water-conducting fracture zones, non-invasive geophysical techniques such as time-lapse electrical resistivity tomography (TL-ERT), magnetic resonance sounding (MRS), and spontaneous potential (SP) have been employed to monitor alterations within the shallow coalfield's aquifer throughout the mining process in the Ningdong coalfield. By conducting meticulous examinations of fluctuations in resistivity, moisture content, and self-potential within the superjacent strata during coal seam extraction, the predominant underground water infiltration strata were ascertained, concurrently enabling the estimation of the development elevation of water-conducting fracture zones. This outcome furnishes a geophysical underpinning for endeavors concerning local water-preserved coal mining and ecological rehabilitation.

Identification and quantification of microplastics in salts by complementary approaches using pyrolysis-gas chromatography/quadrupole-time of flight mass spectrometry (Py-GC/QTOFMS) and laser direct infrared (LDIR) chemical imaging analysis.

Microplastics (MPs) and nanoplastics (NPs) have been suspected as contaminants in various foodstuffs, including salts, all over the world. Regarding the different sizes and polymer types, the mass concentrations of actual plastic particles in salt are not very clear. The purpose of this study is to develop a scalable method for qualitative and quantitative analysis of MPs and NPs by using Pyrolysis Gas Chromatography Quadrupole-Time of Flight mass spectrometry (Py-GC/QTOFMS) to detect their mass concentrations in salt samples. The targeted and suspected lists of polymers in salts were compiled based on the combined results of the high-resolution mass spectrometry (HRMS) full scanning with auxiliary MS dataset and the laser direct infrared (LDIR) chemical imaging analysis. The seven targeted MPs with polymer standards, i.e., polyvinyl chloride (PVC), polymethyl methacrylate (PMMA), polypropylene (PP), polystyrene (PS), polyethylene (PE), polyethylene terephthalate (PET), and polycarbonate (PC), were first subjected to a full MS scanning mode of the Py-GC/QTOFMS analysis. Subsequently, the parental masses of their pyrolysis compounds were used as the seeds to generate the related daughter masses. This process established both retention time and mass-pairs matching for the target MS/MS mode for enabling the identification and quantification of the particles. The suspected MPs with a matching degree >0.65 in the LDIR list were explored either by the full scan MS. Only PVC was identified, and PET was suspected. The Py-GC/QTOFMS result is complementary and comparable to the LDIR detection with the matching degree >0.85. We identified that PVC and PET (suspected) can be measured in both commercial and bulk sea salts, and their concentrations in sea salts are much higher than in rock salts, implying heavy contamination of the seawater.

Human respiratory syncytial virus subgroups A and B outbreak in a kindergarten in Zhejiang Province, China, 2023.

Background: In May-June 2023, an unprecedented outbreak of human respiratory syncytial virus (HRSV) infections occurred in a kindergarten, Zhejiang Province, China. National, provincial, and local public health officials investigated the cause of the outbreak and instituted actions to control its spread. Methods: We interviewed patients with the respiratory symptoms by questionnaire. Respiratory samples were screened for six respiratory pathogens by real-time quantitative polymerase chain reaction (RT-PCR). The confirmed cases were further sequenced of G gene to confirm the HRSV genotype. A phylogenetic tree was reconstructed by maximum likelihood method. Results: Of the 103 children in the kindergarten, 45 were classified as suspected cases, and 25 cases were confirmed by RT-PCR. All confirmed cases were identified from half of classes. 36% (9/25) were admitted to hospital, none died. The attack rate was 53.19%. The median ages of suspected and confirmed cases were 32.7 months and 35.8 months, respectively. Nine of 27 confirmed cases lived in one community. Only two-family clusters among 88 household contacts were HRSV positive. A total of 18 of the G gene were obtained from the confirmed cases. Phylogenetic analyses revealed that 16 of the sequences belonged to the HRSV B/BA9 genotype, and the other 2 sequences belonged to the HRSV A/ON1 genotype. The school were closed on June 9 and the outbreak ended on June 15. Conclusion: These findings suggest the need for an increased awareness of HRSV coinfections outbreak in the kindergarten, when HRSV resurges in the community after COVID-19 pandemic.

Profiles and transplacental transfer of per- and polyfluoroalkyl substances in maternal and umbilical cord blood: A birth cohort study in Zhoushan, Zhejiang Province, China.

Per- and polyfluoroalkyl substances (PFAS) can pass through the placental barrier and pose health risks to fetuses. However, exposure and transplacental transfer patterns of emerging PFAS remain unclear. Here, 24 PFAS were measured in paired maternal whole blood (n = 228), umbilical cord whole blood (n = 119) and serum (n = 120). Orthogonal partial least-squares discriminant analysis (OPLS-DA) was used to differentiate PFAS between different matrices. The transplacental transfer (TPT) of PFAS was calculated using cord to maternal whole blood concentration ratios. PFOS and PFOA were still the dominant PFAS in maternal samples. The emerging PFAS had higher TPT than PFOS and PFOA. Moreover, PFAS with the same chain length but different functional groups and C-F bonds showed different TPT, such as PFOS and PFOSA (C8, median: 0.090 vs. 0.305, p < 0.05) and PFHxS and 4:2 FTS (C6, median: 0.220 vs. 1.190, p < 0.05). A significant sex difference in 4:2 FTS (median: boys 1.250, girls 1.010, p < 0.05) were found. Furthermore, we observed a significant U-shaped trend for the TPT of carboxylates with increasing carbon chain length. PFAS showed a compound-specific transfer through placental barrier and a compound-specific distribution between different matrices in this study.

Simultaneous speciation analysis of arsenic and iodine in human urine by high performance liquid chromatography-inductively coupled plasma mass spectrometry.

A high-performance liquid chromatography-inductively coupled plasma mass spectrometry-based method was developed for the simultaneous determination of four iodine species (i.e. iodate, 3-iodo-tyrosine, 3,5-diiodo-tyrosine, and iodide) and six arsenic species (i.e. arsenobetaine, arsenite, dimethylarsinic acid, arsenocholine, methylarsonic acid, and arsenate) in human urine. The chromatographic separation was performed on a Dionex IonPac As7 anion exchange column. The mobile phase was initiated with 0.5 mmol/L ammonium carbonate solution, followed by 50 mmol/L ammonium carbonate/100 mmol/L ammonium nitrate solution (with 4% methanol). The limits of quantification of the analytes ranged from 0.045 to 2.26 µg/L. At three spiked levels (10.0, 20.0, 50.0 µg/L), the average recoveries (%) ranged from 87.4 to 113.1%, and the relative standard deviations (RSD, %) ranged from 0.4 to 17.2%. The ratio of the sum of six arsenic species to the total arsenic measured by ICPMS ranged from 77.4 to 121.2%, and the ratio of the sum of the four iodine species to the total iodine ranged from 70.7 to 114.7%, indicating a good agreement between these two methods for both arsenic and iodine.

Synthesis of Fluoro 3(2H)-Furanones via a TFA-Catalyzed Dehydrofluorinative Cyclization of 2,2-Difluoro-3-hydroxy-1,4-diketones.

A TFA-catalyzed dehydrofluorinative cyclization of 2,2-difluoro-3-hydroxy-1,4-diketones has been developed in the presence of amines under mild conditions in which the difluorinated substrates are readily prepared according to our reported literature. This protocol provides a rapid construction of fluoro 3(2H)-furanones in good to excellent yields with good functional group tolerance. Easy scale-up synthesis also shows a practical advantage.

Metabolism of barium in the human body after suicidal ingestion: A CARE-compliant case report.

RATIONALE: Thus far, barium poisoning has been seldom reported and the metabolism of barium in human body has not been explored. PATIENT CONCERNS: A 21-year-old young man was taken to the local hospital by "120 emergency medical services" after a suicidal attempt. About 100 mL of barium chloride solution with a concentration of 100 g/L was ingested, while the actual amount of ingested barium chloride solution was unclear because of immediate vomiting after the ingestion. DIAGNOSES: About 2 hours after the suicidal ingestion, the patient was presented with somnolence, the pulse rate was 67 beats per minute, the blood pressure was 158/92 mm Hg, but he exhibited no nausea or vomiting. About 3 hours after the ingestion, the blood concentration of potassium was 1.5 mmol/L. INTERVENTIONS: The patient received gastric lavage by magnesium sulfate solution, intravenous sodium thiosulfate, and potassium supplementation. Other symptomatic treatments were applied simultaneously. To investigate the metabolism of barium in the human body, we measured the concentration of barium in 9 groups of paired serum and urine samples sequentially collected from the patient. OUTCOMES: The patient was rescued successfully. LESSONS: The serum concentration of barium decreased rapidly in the first 24 hours. In this period, prompt and massive potassium supplementation and other symptomatic treatments are effective and recommended.

A preliminary cumulative risk assessment of Diethylhexyl phthalate and Dibutyl phthalate based on the inhibition of embryonic development via the PPARγ pathway.

BACKGROUND: Diethylhexyl phthalate (DEHP) and dibutyl phthalate (DBP) are the two most widely used plasticizers (PAEs) that may act as endocrine disruptors and cause developmental toxicity. METHODS: We measured intrauterine exposure to DEHP and DBP which are the two most widely used phthalates (PAEs) in the cord blood of 50 postpartum women using ultra-HPLC-tandem mass spectrometry and solid-phase extraction. The embryotoxicity of DEHP and DBP was evaluated using the human embryonic stem cell test (hEST). Based on the intrauterine exposure concentration of DEHP and DBP in pregnant women and the reference point of toxic effects in hEST, we used the reference point index (RPI) method to assess the cumulative risk of DBP and DEHP. RESULTS: The mean concentrations of DEHP and DBP were 99.9 µg/L and 24.7 µg/L, respectively. DEHP and DBP were weakly embryotoxic, and the benchmark dose lower confidence intervals were 29.99 and 0.99 µg/mL, respectively, as determined using hEST. Both DEHP and DBP inhibited embryonic development via PPAR/PTEN/Akt signal pathway. CONCLUSION: The findings suggest that the cumulative risk in pregnant women with a high level of exposure should receive more attention in the future.

Association Between the Ambient Fine Particulate Pollution and the Daily Internal Medicine Outpatient Visits in Zhoushan, China: A Time-Series Study.

Background: There has been a recent worsening of air pollution in China, which poses a huge threat to public health by inducing and promoting circulatory and respiratory diseases. This study aimed to explore the association between the concentration of air pollution and daily internal medicine outpatient visits registered for the treatment of circulatory and respiratory symptoms in Zhoushan, China using a time-series method. Methods: We validated and acquired the daily internal medicine outpatient visits records between January 1, 2014, and December 31, 2019, from the Zhoushan Center for Disease Control and Prevention in Zhejiang, China. Further, we collected the daily average records of the ambient air pollutants from the Zhoushan Environmental Monitoring Centre within the same duration. A generalized additive model with the natural splines was constructed to explore the association between the ambient air pollutants and daily internal medicine outpatient visits. Further, we conducted a lag analysis by using the distributed lag non-linear model to estimate the time-delayed effects of the air pollutants on the daily internal medicine outpatient visits. Results: A total of 2,190,258 daily internal medicine outpatient visits with a mean of 202.4 visits per day were recorded. The non-linear relationships were found among particulate matter2.5 (PM2.5), sulfur dioxide (SO2), and the daily internal medicine outpatient visits. Overall, PM2.5 was positively correlated with the daily internal medicine outpatient visits. Both ozone (O3) and SO2 had significant delayed effects on the daily internal medical outpatient numbers; however, PM2.5 only showed a short-term risk. Conclusion: Short-term exposure to PM2.5 was associated with an increase in the daily internal medicine outpatient visits for circulatory and respiratory diseases/symptoms in Zhoushan, China. SO2 and O3 were shown to induce significant effects after a concentration-dependent time lag.

Seroprevalence of coxsackievirus A16 antibody among people of various age groups: a systematic review and meta-analysis.

BACKGROUND: Coxsackie virus group A type 16 (CoxA16) is the main pathogen and usually an alternative to or joins in prevalence with enterovirus 71 (EV71) causing hand, foot and mouth disease (HFMD). The objective of this study was to estimate the seroprevalence of CoxA16 antibody among people of various age groups by a systematic review and meta-analysis. METHODS: The literature of seroprevalence of CoxA16 antibody among people has been systematically searched through databases from the date of their establishment to Jan. 2021. Estimates of seroprevalence of CoxA16 antibody by gender and age groups have been summarized by using fixed- and random- effect models. All analyses have been conducted in STATA version 12.0 software. RESULTS: A total of 14 publications with 9 in English and 5 in Chinese containing 9562 samples were finally included in the meta-analysis. The seroprevalence of CoxA16 antibody reported in different studies range from 24.85 to 76.92 %. Meta-analysis has revealed that the seroprevalence of CoxA16 antibody was 56.3 % (95 %CI: 47.7 %~64.9 %) in the overall population and 55.1 % (95 %CI: 44.1 %~66.1 %) in the Chinese population. Subgroup analysis by gender has revealed that the seroprevalence of CoxA16 antibody was 56.1 % (95 %CI: 45.2 %~67.1 %) in males and 60.0 % (95 %CI: 50.0 %~69.9 %) in females. Subgroup analysis by age groups has revealed that the seroprevalence of CoxA16 antibody was 49.1 % (95 %CI: 36.2 %~62.0 %) in the 0 ~ 5 age group and 63.9 % (95 %CI: 53.1 %~74.7 %) in the over 5 age group. Begg's funnel plots have suggested that there were no publication bias in all groups. Sensitive analysis has suggested that the result of the meta-analysis was stable. CONCLUSIONS: The seroprevalence of CoxA16 antibody was closely related to age. Children under 5 years old were the main susceptible groups for CoxA16 and also the key groups for the prevention and control of HFMD.

Sequencing on an imported case in China of COVID-19 Delta variant emerging from India in a cargo ship in Zhoushan, China.

A cluster of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections was found in a cargo ship under repair in Zhoushan, China. Twelve of 20 crew members were identified as SARS-CoV-2 positive. We analyzed four sequences and identified them all in the Delta branch emerging from India with 7-8 amino acid mutation sites in the spike protein.

SARS-CoV-2 viral shedding characteristics and potential evidence for the priority for faecal specimen testing in diagnosis.

This study aimed to identify the specimen type that has high positivity and its proper sampling time for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) testing to promote diagnostic efficiency. All SARS-CoV-2-infected patients with a laboratory-confirmed diagnosis in Zhoushan City were followed up for viral shedding in respiratory tract specimens and faecal samples. Positivity was analysed both qualitatively and quantitatively by proper statistical approaches with strong testing power. Viral shedding in respiratory tract and faecal specimens was prolonged to 45 and 40 days after the last exposure, respectively. The overall positive rate in respiratory tract specimens was low and relatively unstable, being higher in the early-to-mid stage than in the mid-to-late stage of the disease course. Compared with respiratory tract specimens, faecal samples had a higher viral load, higher overall positive rate, and more stable positivity in different disease courses and varied symptomatic status. Faecal specimens have the potential ability to surpass respiratory tract specimens in virus detection. Testing of faecal specimens in diagnosis, especially for identifying asymptomatic carriers, is recommended. Simultaneously, testing respiratory tract specimens at the early-to-mid stage is better than testing at the mid-to-late stage of the disease course. A relatively small sample size was noted, and statistical approaches were used to address it. Information was missing for both specimen types at different stages of the disease course due to censored data. Our research extends the observed viral shedding in both specimen types and highlights the importance of faecal specimen testing in SARS-CoV-2 diagnosis. Healthcare workers, patients, and the general public may all benefit from our study findings. Disposal of sewage from hospitals and residential areas should be performed cautiously because the virus sheds in faeces and can last for a long time.

Investigation of Damage Reduction When Dry-Drilling Aramid Fiber-Reinforced Plastics Based on a Three-Point Step Drill.

Aramid fiber-reinforced plastic (AFRP) is widely used in bullet-proof and armor structures, and is difficult to drill because of the high-toughness aramid fibers with ductile fracturing-differently from carbon fiber. Therefore, drilling quality cannot be ensured by the drilling used for carbon fiber-reinforced plastic, and frequently, delamination and burrs occur in the drilling process. This article first established a two-dimensional cutting model for analyzing the fiber deformation and material interface cracking. According to the model, reducing the thrust force and the radial force of the edge on the fibers is an effective way to reduce the fiber deformation, and a three-point step drill is proposed further. Comparative experiments were carried out among twist drilling, candle core drilling and three-point step drilling under three drilling parameters. The results show that the three-point step drill changed the traditional cutting behavior on the drill-exit material into a compound process. Finally, the AFRP was cut effectively with the novel drill with a small thrust force, and the delamination and "burrs area" were reduced through different drilling parameters. In summary, the three-point step drill can drill the AFRP without delamination and burrs with 0.02 mm/rev, which provides a new solution of cost-effective production for AFRP manufacturers.

Limnobacter alexandrii sp. nov., a thiosulfate-oxidizing, heterotrophic and EPS-bearing Burkholderiaceae isolated from cultivable phycosphere microbiota of toxic Alexandrium catenella LZT09.

A novel Gram-negative, aerobic, motile and short rod-shaped bacterium with exopolysaccharides production, designated as LZ-4T, was isolated from cultivable phycosphere microbiota of harmful algal blooms-causing marine dinoflagellate Alexandrium catenella LZT09 which produces paralytic shellfish poisoning toxins. Strain LZ-4T was able to use thiosulfate (optimum concentration 10 mM) as energy source for bacterial growth. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain LZ-4T belonged to the genus Limnobacter, showing high 16S rRNA gene sequences similarities with L. thiooxidans DSM 13612T (99.4%), L. humi NBRC 11650T (98.2%) and L. litoralis NBRC 105857T (97.2%), respectively. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between LZ-4T and L. thiooxidans DSM 13612T were 78.9 and 21.9%, respectively. Both values were far lower than the thresholds (95-96% for ANI and 70% for dDDH) generally accepted for new species delineation. The respiratory quinone of strain LZ-4T was Q-8. The dominant cellular fatty acids were determined as summed feature 3 (C16:1 ω6c/ω7c), summed feature 8 (C18:1 ω6c/ω7c) and C16:0. Polar lipids profile consisted of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, two unidentified aminolipids and three unidentified polar lipids. The genomic DNA G+C content of strain LZ-4T was 52.5 mol%. Based on polyphasic characterization, strain LZ-4T represents a novel species of the genus Limnobacter, for which the name Limnobacter alexandrii sp. nov. is proposed. The type strain is LZ-4T (=CCTCC AB 2019004T =KCTC 72281T).

Infantile phthalate metabolism and toxico/pharmacokinetic implications within the first year of life.

BACKGROUND: Infantile development of phthalate metabolism is crucial for risk assessment of endocrine disruption and has important toxico/pharmacokinetic implications. OBJECTIVES: To characterize temporal variability in urinary phthalate metabolites in infants and to examine their growth-dependent detoxification. METHODS: In this cohort study, urine samples (n = 876) from 155 healthy Chinese infants were collected serially at eight time points from birth to one year old. Free and total (i.e., free plus glucuronide conjugated) phthalate metabolites (PMEs) were measured by LC/MS/MS. Time variability in PMEs and PME metabolism capacity was characterized using intraclass correlation coefficients (ICCs) and linear mixed regression models. RESULTS: Concentrations of most PMEs changed significantly, with ICCs ranging from 0.213 to 0.318, and trends increased significantly over time (p < 0.001), while MEHP showed fair reproducibility (ICC = 0.480). Glucuronidation increased considerably (ICC ≤ 0.250; p < 0.001) for most PMEs but not for MMP or MEHP. Ester-chain ω-/ω-1-oxidation and α-/ß-oxidation patterns of MEHP steeply increased from 3 months to 8 months, where they peaked, resulting in a molar percentage of MEHP in ΣDEHP showing the inversion pattern. MEHP detoxification through oxidation of the hydrophobic ester-chain is apparently a priority for carboxyl glucuronidation in infants. CONCLUSIONS: Infant phthalate exposure is prevalent, but they cannot metabolize or eliminate these compounds as efficiently as adults, especially during the first 6 months of life. From an environmental biomonitoring view, age-dependent phthalate metabolism provides crucial implications for infantile ontogeny and health risk assessment within the first year of life.

Transmission of COVID-19 in the terminal stages of the incubation period: A familial cluster.

We report a familial cluster of 2019 novel coronavirus disease (COVID-19) to assess its potential transmission during the incubation period. The first patient in this familial cluster was identified during the presymptomatic period, as a close contact of a confirmed patient. Five family members had close contact with this first patient during his incubation period, with four of them confirmed positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in the subsequent sampling tests.

Detection of Novel Coronavirus by RT-PCR in Stool Specimen from Asymptomatic Child, China.

We report an asymptomatic child who was positive for a coronavirus by reverse transcription PCR in a stool specimen 17 days after the last virus exposure. The child was virus positive in stool specimens for at least an additional 9 days. Respiratory tract specimens were negative by reverse transcription PCR.

Molecular evolution of GII.P17-GII.17 norovirus associated with sporadic acute gastroenteritis cases during 2013-2018 in Zhoushan Islands, China.

In this study, we investigated the molecular characteristics and spatio-temporal dynamics of GII.P17-GII.17 norovirus in Zhoushan Islands during 2013-2018. We collected 1849 samples from sporadic acute gastroenteritis patients between January 2013 and August 2018 in Zhoushan Islands, China. Among the 1849 samples, 134 (7.24%) samples were positive for human norovirus (HuNoV). The complete sequence of GII.17 VP1 gene was amplified from 31 HuNoV-positive samples and sequenced. A phylogenetic tree was constructed based on the full-length sequence of the VP1 gene. Phylogenetic analysis revealed that the GII.17 genotype detected during 2014-2018 belongs to the new GII.17 Kawasaki variant. Divergence analysis revealed that the time of the most recent common ancestor (TMRCA) of GII.17 in Zhoushan Islands was estimated to be between 1997 and 1998. The evolutionary rate of the VP1 gene of the GII.17 genotype norovirus was 1.14 × 10-3 (95% HPD: 0.62-1.73 × 10-3) nucleotide substitutions/site/year. The spatio-temporal diffusion analysis of the GII.17 genotype identified Hong Kong as the epicenter for GII.17 dissemination. The VP1 gene sequence of Zhoushan Island isolates correlated with that of Hong Kong and Japan isolates.

Methyl mercury concentrations in seafood collected from Zhoushan Islands, Zhejiang, China, and their potential health risk for the fishing community: Capsule: Methyl mercury in seafood causes potential health risk.

Seafood is an important exposure route for mercury, especially methyl mercury (MeHg). Therefore, we quantified MeHg concentrations in 69 species of seafood including fish, crustaceans and mollusks collected from Zhoushan Islands, China. MeHg concentrations ranged from <0.0020-0.2098 µg/g and did not exceed the threshold limit of 1 µg/g in all sampled species, However, MeHg concentrations significantly differed among fish species (0.0085-0.2098 mg kg-1), crustaceans (<0.002-0.0221 mg kg-1) and mollusks (<0.002-0.1389 mg kg-1). The trophic magnification factor (TMF) was determined on the basis of the trophic level (TL). The TL values for fish, crustaceans and mollusks were above 3 when the TMF values were >1. The daily dietary intake and hazard quotient for MeHg were calculated to estimate exposure and health risk through seafood consumption by local inhabitants. The calculated HQ was lower than 1, thus indicating that the exposure was below the risk threshold of related chronic diseases. However, higher MeHg concentrations in fish species such as Scoliodon sorrakowah and Auxis thazard are concerning and may pose health risk through continuous consumption by local inhabitants.

Potential Presymptomatic Transmission of SARS-CoV-2, Zhejiang Province, China, 2020.

We report a 2-family cluster of persons infected with severe acute respiratory syndrome coronavirus 2 in the city of Zhoushan, Zhejiang Province, China, during January 2020. The infections resulted from contact with an infected but potentially presymptomatic traveler from the city of Wuhan in Hubei Province.