Predicting the incidence of infectious diarrhea with symptom surveillance data using a stacking-based ensembled model.

BACKGROUND: Infectious diarrhea remains a major public health problem worldwide. This study used stacking ensemble to developed a predictive model for the incidence of infectious diarrhea, aiming to achieve better prediction performance. METHODS: Based on the surveillance data of infectious diarrhea cases, relevant symptoms and meteorological factors of Guangzhou from 2016 to 2021, we developed four base prediction models using artificial neural networks (ANN), Long Short-Term Memory networks (LSTM), support vector regression (SVR) and extreme gradient boosting regression trees (XGBoost), which were then ensembled using stacking to obtain the final prediction model. All the models were evaluated with three metrics: mean absolute percentage error (MAPE), root mean square error (RMSE), and mean absolute error (MAE). RESULTS: Base models that incorporated symptom surveillance data and weekly number of infectious diarrhea cases were able to achieve lower RMSEs, MAEs, and MAPEs than models that added meteorological data and weekly number of infectious diarrhea cases. The LSTM had the best prediction performance among the four base models, and its RMSE, MAE, and MAPE were: 84.85, 57.50 and 15.92%, respectively. The stacking ensembled model outperformed the four base models, whose RMSE, MAE, and MAPE were 75.82, 55.93, and 15.70%, respectively. CONCLUSIONS: The incorporation of symptom surveillance data could improve the predictive accuracy of infectious diarrhea prediction models, and symptom surveillance data was more effective than meteorological data in enhancing model performance. Using stacking to combine multiple prediction models were able to alleviate the difficulty in selecting the optimal model, and could obtain a model with better performance than base models.

Circulating inflammatory cytokines and psoriasis risk: A systematic review and meta-analysis.

BACKGROUND: Psoriasis is a systemic immune-mediated chronic inflammatory skin disease; its systemic manifestations and periodic recurrence negatively affect a patient's quality of life. Inflammatory cytokines are known to have an important role in the onset and progression of psoriasis, however, data on the association between circulating inflammatory cytokines and psoriasis risk is inconclusive. Here, we explore the relevance of circulating proinflammatory factors to the pathogenesis of psoriasis using a meta-analysis. OBJECTIVE: To explore the association between circulating levels of inflammatory factors and psoriasis to elucidate the mechanisms underlying psoriasis and improve clinical diagnosis and treatment. METHODS: We systematically retrieved articles published in PubMed, EMBASE, the Cochrane Library and the Web of Science from the establishment of each database to January 2023. The standard mean difference (SMD) in cytokine levels of individuals with psoriasis and healthy controls was used to check for correlations between circulating inflammatory factor levels and psoriasis. RESULTS: Fifty-seven studies, with data from 2838 patients, were retrieved and included in the meta-analysis. Eleven inflammatory factors were studied (circulating interleukin-2 (IL-2), IL-4, IL-12, IL-17, IL-18, IL-22, IL-23, IL-35, IL-36, transforming growth factor-beta (TGF-ß) and gamma-interferon (IFN-γ)). Of these, IL-2 [SMD = 1.29 (95% CI: 0.61-1.97; P <0.001)], IL-17 [SMD = 0.71 (95% CI: 0.12-1.30; P = 0.018)], IL-18 [SMD = 1.27 (95% CI: 0.64-1.90; P <0.001)], and IFN-γ [SMD = 1.90 (95% CI: 1.27-2.52; P <0.001)] levels had significant correlations with psoriasis. CONCLUSION: Increased serum concentrations of the circulating inflammatory cytokines IL-2, IL-17, IL-18 and IFN-γ were significantly correlated with psoriasis.

TFAP2C exacerbates psoriasis-like inflammation by promoting Th17 and Th1 cells activation through regulating TEAD4 transcription.

BACKGROUND: Psoriasis is one of the chronic and autoimmune skin diseases. It is important to uncover the mechanisms underlying the psoriasis. Transcription factor activator protein (TFAP-2) gamma, also known as AP2-gamma, is a protein encoded by the TFAP2C gene. Immune-mediated pathophysiological processes could be linked to psoriasis, but the mechanism is still unclear. Therefore, to date the cause of psoriasis has not been understood completely. MATERIALS AND METHODS: Psoriasis is a complex disease triggered by genetic, immunological, and environmental stimuli. Keratinocytes play an important role in both initiation and maintenance phases of psoriasis. A psoriatic keratinocyte model was established by stimulating high sensitivity of human epidermal keratinocytes (HaCaT) to topoisomerase inhibitor cell lines using the accumulation of M5 cytokines comprising interleukin (IL)-17A, IL-22, oncostatin M, IL-1α, and tumor necrosis factor-α (TNF-α). The TFAP2C and transcriptional enhanced associate domain 4 (TEAD4) genes expression was evaluated by reverse transcription-quantitative polymerase chain reaction. Western blot analysis was used to examine protein expression. Cell viability (quantitative) of keratinocytes, including cytotoxicity, proliferation, and cell activation, was evaluated by the MTT assay. The relative percentage values of interleukin (IL)-17a, interferon gamma, and IL-4+ cells were measured by flow cytometry. Accordingly, chromatin immunoprecipitation and luciferase reporter assays were applied to evaluate the binding affinity of TFAP2C and TEAD4 promoter. RESULTS: Level of the TFAP2C gene was elevated in the lesional skin of psoriasis patients. On the other hand, silencing of the TFAP2C gene suppressed the proliferation and inflammatory response in M5-induced keratinocytes. In addition, inhibition of TFAP2C alleviated imiquimod (IMQ)-induced skin injury in mice model. We also observed that suppression of TFAP2C inhibited the activation of T-helper 17 (Th17) and Th1 cells in IMQ-induced mice model. Mechanically, TFAP2C promoted TEAD4 transcriptional activation. CONCLUSION: TFAP2C exacerbated psoriasis-like inflammation by increasing the activation of Th17 and Th1 cells by regulating TEAD4 transcription. This finding clearly indicated that TFAP2C could be considered a valuable biomarker for the prevention and treatment for psoriasis.

TFAP2C exacerbates psoriasis-like inflammation by promoting Th17 and Th1 cells activation through regulating TEAD4 transcription

Background: Psoriasis is one of the chronic and autoimmune skin diseases. It is important to uncover the mechanisms underlying the psoriasis. Transcription factor activator protein (TFAP-2) gamma, also known as AP2-gamma, is a protein encoded by the TFAP2C gene. Immune-mediated pathophysiological processes could be linked to psoriasis, but the mechanism is still unclear. Therefore, to date the cause of psoriasis has not been understood completely. Materials and methods: Psoriasis is a complex disease triggered by genetic, immunological, and environmental stimuli. Keratinocytes play an important role in both initiation and maintenance phases of psoriasis. A psoriatic keratinocyte model was established by stimulating high sensitivity of human epidermal keratinocytes (HaCaT) to topoisomerase inhibitor cell lines using the accumulation of M5 cytokines comprising interleukin (IL)-17A, IL-22, oncostatin M, IL-1α, and tumor necrosis factor-α (TNF-α). The TFAP2C and transcriptional enhanced associate domain 4 (TEAD4) genes expression was evaluated by reverse transcription-quantitative polymerase chain reaction. Western blot analysis was used to examine protein expression. Cell viability (quantitative) of keratinocytes, including cytotoxicity, proliferation, and cell activation, was evaluated by the MTT assay. The relative percentage values of interleukin (IL)-17a, interferon gamma, and IL-4+ cells were measured by flow cytometry. Accordingly, chromatin immunoprecipitation and luciferase reporter assays were applied to evaluate the binding affinity of TFAP2C and TEAD4 promoter. Results: Level of the TFAP2C gene was elevated in the lesional skin of psoriasis patients. On the other hand, silencing of the TFAP2C gene suppressed the proliferation and inflammatory response in M5-induced keratinocytes (AU)

Application of optical coherence tomography and keratograph in the measurements of lower lid margin thickness.

PURPOSE: This study aims to investigate the applicability of lower lid margin thickness (LLMT) measurements in adults with and without meibomian gland dysfunction (MGD) by optical coherence tomography (OCT) and keratograph. METHODS: This is a cross-sectional, observational study. A hundred and eight volunteers aged 20 to 79, including 68 MGD patients and 40 normal subjects, were recruited. Using OCT and keratograph to measure the LLMT from the posterior lash line to anterior edge or outer edge of the tear meniscus was separately performed two times by the same person. RESULTS: The mean age of normal and MGD subjects was 50.5 ± 14.2 years and 55.8 ± 15.5 years, respectively. The LLMT with OCT and keratograph in MGD patients was significantly greater than that in normal subjects (1.06 ± 0.27 and 1.03 ± 0.25 mm vs. 0.90 ± 0.20 and 0.86 ± 0.16 mm, respectively). In both normal and MGD subjects, the tear meniscus height and LLMT with OCT were both greater than that with keratograph (P < 0.05), and intraclass correlation coefficient (ICC) demonstrated a good agreement in the LLMT measurements between two devices (ICC = 0.83 and 0.79, respectively). Additionally, the LLMT in MGD patients was appeared to be positively correlated with meiboscore (rs = 0.37, P = 0.002). CONCLUSIONS: The OCT and keratograph were two reliable tools in the LLMT measurements, which may have potential applications for diagnosis and evaluation of MGD. Furthermore, we found that the LLMT measured by OCT was greater than that measured by keratograph.

Case report: A case of corneal epithelial injury associated with Pthiriasis palpebrarum.

Significance: Phthiriasis palpebrarum is an uncommon infection due to Phthirus pubis inoculating the eyelashes and surrounding tissues of the eye. Because of its rarity, it may be misdiagnosed as blepharitis or conjunctivitis clinically. Purpose: This report described a rare case of corneal epithelial injury associated with Phthiriasis palpebrarum. Case report: A 59-year-old woman presented with 1 month history of repeated episodes of itching and irritation symptoms in both eyes. A slit-lamp examination was performed, which revealed mild conjunctival hyperemia and corneal epithelial defects in both eyes. On closer examination, crab-like lice, nits, and red pinpoint excretions were seen on her eyelashes and eyelids bilaterally. Corneal fluorescein staining in both eyes was observed, and tear film break-up time (BUT) in each eye was 2 s. Numerous lice were also found attached to the scalp hair. Therefore, a clinical diagnosis of corneal epithelial injury associated with Pthiriasis palpebrarum was made. For treatment, eyelashes with nits and/or lice were removed mechanically with a fine tweezers. Then, 0.01% Hypochlorous Acid eye wash was used to clean the eyelid margin twice daily. Also, she was prescribed a combination of Vitamin A Palmitate eye gel three times a day and Tobradex® eye ointment once daily. Meanwhile, the patient was provided with suggestions on how to improve personal hygiene and environmental hygiene, including cutting of the scalp hair and the application of 0.01% permethrin rinse. One week later, no evidence of lice and nits of the eyelashes and scalp hair was found, and the patient's symptoms and signs also improved significantly. Conclusion: This rare case suggested that the eyelashes of patients presenting with itching and irritation symptoms should be carefully examined with a slit-lamp. Besides removal of the parasites, attention should be paid to the treatment of corneal epithelial injury associated with Pthiriasis palpebrarum.

Case Report: A Case of Cystoid Macular Edema in Retinitis Pigmentosa With Central Retinal Vein Occlusion.

Significance: Cystoid macular edema (CME) is a common complication of retinitis pigmentosa (RP). However, CME in RP with central retinal vein occlusion (CRVO) is rare. Prompt administration of anti-vascular endothelial growth factor (anti-VEGF) medication can achieve a satisfactory prognosis. Purpose: This report describes a case of using anti-VEGF medication to treat CME secondary to RP with impending or mild CRVO. Case Report: A 26-year-old female presented for blurred vision in both eyes. Best-corrected visual acuity (BCVA) was 20/50 in the right eye and finger-counting in the left eye. According to ophthalmic examinations, CME secondary to RP in the right eye and CME secondary to RP with impending or mild CRVO in her left eye can be diagnosed. Central macular thickness (CMT) was 554 µ m in the right eye and 831 µm in the left eye. Only the left eye was treated with a single intravitreal injection of anti-VEGF medication. One month later, BCVA increased to 20/200 and CMT decreased to 162 µm in the left eye. Interestingly, BCVA in the right eye also had an improvement (20/40) and intraretinal fluid decreased significantly. However, 3 months after injection, these improvements of both eyes were not maintained. Conclusion: This is the second case of RP with CRVO. Intravitreal injection of anti-VEGF medication for addressing CME secondary to RP with CRVO is an effective treatment, but it needs to be reinjected.

Measurement of the Lid Margin Thickness in Meibomian Gland Dysfunction with Vernier Micrometer.

INTRODUCTION: To investigate the lid margin thickness (LMT) from the posterior lash line to the mucocutaneous junction at the middle position in adults with and without meibomian gland dysfunction (MGD) by vernier micrometer (VM). METHODS: This is a cross-sectional, observational study. A hundred eyes from 100 volunteers aged 20 to 79, including 56 normal participants and 44 participants with MGD, were recruited. Measurements of the LMT by VM were performed by the same person. RESULTS: The mean age of 56 normal subjects (24 males and 32 females) and 44 MGD subjects (16 males and 28 females) was 40.0 ± 13.2 years and 42.7 ± 17.1 years, respectively. There was a significant difference in the upper LMT between normal and MGD subjects (1.36 ± 0.25 vs. 1.60 ± 0.27 mm, P < 0.001), but not in the lower LMT (1.0 ± 0.23 vs. 1.10 ± 0.28 mm, P = 0.07). In both normal and MGD subjects, the upper or lower LMT was significantly positively correlated with age (P < 0.05), and the upper LMT was greater than the lower LMT (P < 0.001). In addition, the lower LMT in MGD subjects was significantly positively correlated with meibum expressibility (rs = 0.35, P = 0.02). CONCLUSIONS: The LMT was closely related to age and could be an important indicator for detecting MGD. Furthermore, we found that the upper LMT was greater than the lower LMT, and the lower LMT in MGD subjects seemed to be related to meibum expressibility.

Abnormal Levels of Serum Ferroptosis-Related Biomarkers in Diabetic Retinopathy.

Purpose: This study aimed to measure the concentrations of ferroptosis-related biomarkers, namely, iron (Fe), lipid peroxide (LPO), reactive oxygen species (ROS), glutathione peroxidase-4 (GPX4), and glutathione (GSH) in DR in the attempt to evaluate the diagnostic performance of these biomarkers. Methods: This study included 30 NPDR patients, 30 PDR patients, and 30 healthy subjects matched in age and sex. The concentrations of Fe, LPO, ROS, GPX4, and GSH in serum of the subjects were measured. Results: Compared with the normal group, GPX4 and GSH concentrations were significantly lower, and LPO, Fe, and ROS concentrations were significantly higher in DR patients. Compared with the PDR group, the NPDR group had higher concentrations of LPO, Fe, and ROS and lower concentrations of GPX4 and GSH, but there was no statistical difference in Fe, GPX4, and GSH. ROC curve shows that ferroptosis-related biomarkers have accumulated accuracy in NPDR and PDR. Conclusion: This study shows that ferroptosis-related biomarkers may be involved in the pathological process of DR and can be used as one of the biomarkers of DR.

Blink-sensing glasses: A flexible iontronic sensing wearable for continuous blink monitoring.

Blink reflex has long been considered closely related to physiological states, from which abundant information on ocular health and activities can be revealed. In this study, a smart glasses wearable has been developed, incorporating a flexible and sensitive pressure sensor, to monitor blink patterns by continuously detecting ocular muscular movements, referred to as blink-sensing glasses. By applying the emerging flexible iontronic sensing (FITS) sensor with the sensitivity of 340 pF/mmHg, the skin pressure variations induced by movements of the orbicularis oculi muscles can be monitored in real time. The blink-sensing glasses can successfully capture blink patterns with a high accuracy of 96.3% and have been used to differentiate the blink features from both dry-eye subjects and healthy controls. This device can be potentially used as a new clinical and research monitoring tool for continuous eye blink analysis, while providing patients with high comfortableness in long-term ambulatory and home settings.

Measurement of the Lower Lid Margin Thickness by Oculus Keratograph.

OBJECTIVES: To investigate the lower lid margin thickness (LLMT) from the posterior lash line to the anterior edge of tear meniscus with Oculus Keratograph 4 (K4). METHODS: This was a prospective, single-center, observational study. A total of 90 volunteers aged 18 to 79 years with no ocular diseases were included in this study. The LLMT of 90 subjects was measured twice by the same person with K4. To determine the reliability of K4, measuring the LLMT of 30 normal subjects was separately performed by two operators. RESULTS: The LLMT measurements with K4 between two operators demonstrated a good reproducibility (0.94±0.18 vs. 0.96±0.16 mm; intraclass correlation coefficient=0.88; P=0.18). The mean age of 90 volunteers (42 men and 48 women) was 45.5±14.1 years. The LLMT was 0.95±0.17 mm, which was a significant positive correlation with age (rs=0.57; P<0.001). In addition, there was no significant difference in the LLMT between genders (0.97±0.16 vs. 0.93±0.18 mm; P=0.32). CONCLUSIONS: We found that K4 was a reliable tool in the LLMT measurements, and the LLMT seemed to be closely related to age but not to gender.

An outbreak of rotavirus-related acute gastroenteritis of childcare center in Guangzhou, southern China.

Rotavirus is the most common cause of severe diarrhea in children under 5 y old in the world. The study aims to explore the relationship between rotavirus vaccination and infection in the outbreak of rotavirus gastroenteritis in a childcare center. Earlier immunization and high vaccination rate should be encouraged.

Measurement of the Lower Lid Margin Thickness by Anterior Segment Optical Coherence Tomography.

PURPOSE: To verify the feasibility of using anterior segment optical coherence tomography (AS-OCT) to measure the lower lid margin thickness (LLMT) from posterior lash line to the mucocutaneous junction. METHODS: This was a prospective, single-center, observational study. Fifty-six volunteers between 20 and 79 years old with normal healthy eyes were included in this study. Using AS-OCT to measure the LLMT at the middle position was separately performed by two operators under the same conditions. RESULTS: The mean age of 56 subjects (24 males and 32 females) was 45.4 ± 15.7 years. The LLMT measured by AS-OCT between two operators was 0.86 ± 0.23 mm and 0.85 ± 0.22 mm, respectively. The reliability and repeatability between two operators were evaluated by intraclass correlation coefficient (ICC = 0.97). Based on one operator's measurements, the LLMT was 0.70 ± 0.10 mm at ages 20-29, 0.68 ± 0.09 mm at ages 30-39, 0.94 ± 0.12 mm at ages 40-49, 0.93 ± 0.20 mm at ages 50-59, 1.03 ± 0.15 mm at ages 60-69, and 1.24 ± 0.19 mm at ages 70-79, which indicated a significant positive correlation with age (rs = 0.74, p < 0.001). In addition, there was a significant difference in the LLMT between genders (0.94 ± 0.26 vs. 0.80 ± 0.19 mm, p = 0.03). CONCLUSIONS: A good agreement between two operators indicated that it seemed to be feasible to use AS-OCT to measure the LLMT. Additionally, we found that the LLMT appeared to be closely related to age and gender.

The Rise in Norovirus-Related Acute Gastroenteritis During the Fight Against the COVID-19 Pandemic in Southern China.

Background: There has been a significant decline in the morbidity of almost all infectious diseases during the COVID-19 pandemic. However, while the incidence of norovirus-related acute gastroenteritis declined in Guangzhou, China during the initial period of the pandemic, incidence increased significantly once the new school year began in September 2020. Methods: Norovirus-related acute gastroenteritis clusters and outbreaks were assessed in Guangzhou from 2015 to 2020. Medians and interquartile ranges were compared between groups using the Mann-Whitney U-test, and attack rates were calculated. Results: While 78,579 cases of infectious diarrhea were reported from 2015 to 2019, with an average of 15,716 cases per year, only 12,065 cases of infectious diarrhea were reported in 2020. The numbers of sporadic cases and outbreaks reported from January to August 2020 were lower than the average numbers reported during the same time period each year from 2015 to 2019 but began to increase in September 2020. The number of cases in each reported cluster ranged from 10 to 70 in 2020, with a total of 1,280 cases and an average attack rate of 5.85%. The median number of reported cases, the cumulative number of cases, and the attack rate were higher than the average number reported each year from 2015 to 2019. The intervention time in 2020 was also higher than the average intervention time reported during 2015-2019. The main norovirus genotypes circulating in Guangzhou during 2015-2020 included genogroup 2 type 2 (GII.2) (n = 79, 26.69%), GII.17 (n = 36, 12.16%), GII.3 (n = 27, 9.12%), GII.6 (n = 8, 2.7%), GII.4 Sydney_2012 (n = 7, 2.36%), and GII.4 (n = 6, 2.03%). Conclusions: Our findings illustrate the importance of maintaining epidemiological surveillance for viral gastroenteritis during the COVID-19 pandemic. Local disease prevention and control institutions need to devote sufficient human resources to control norovirus clusters.

Retrospective study identifies infection related risk factors in close contacts during COVID-19 epidemic.

OBJECTIVES: This study aimed to compare the risk of infection of children with that of adults and to explore risk factors of infection with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) by following up close contacts of COVID-19 patients. METHOD: The retrospective cohort study was performed among close contacts of index cases diagnosed with COVID-19 in Guangzhou, China. Demographic characteristics, clinical symptoms and exposure information were extracted. Logistic regression analysis was employed to explore the risk factors. The restricted cubic spline was conducted to examine to the dose-response relationship between age and SARS-CoV-2 infection. RESULTS: The secondary attack rate (SAR) was 4.4% in 1,344 close contacts. The group of household contacts (17.2%) had the highest SAR. The rare-frequency contact (p < 0.001) and moderate-frequency contact (p < 0.001) were associated with lower risk of infection. Exposure to index cases with dry cough symptoms was associated with infection in close contacts (p = 0.004). Compared with children, adults had a significantly increased risk of infection (p = 0.014). There is a linear positive correlation between age and infection (p = 0.001). CONCLUSIONS: Children are probably less susceptible to COVID-19. Close contacts with frequent contact with patients and those exposed to patients with cough symptoms are associated with an increased risk of infection.

Coronavirus disease-2019 (COVID-19) infection in a 3-month-old infant: Clinical features, treatment and probable route of transmission.

This study aims to explore the clinical and epidemiological characteristics of infant patients with coronavirus disease-2019 (COVID-19) infection. Clinical and epidemiological data of a 3-month-old patient with COVID-19 were collected, including general status, clinical results, laboratory tests, imaging characteristics, and epidemiological reports. The infant had no fever but had mild respiratory symptoms. The major laboratory results included normal white blood cell counts and lymphocytopenia, notably with elevated interleukin (IL-)-17A, IL-17F, and tumor necrosis factor (TNF-)-α. The main manifestation of his chest computed tomography scan was pulmonary patchy shadows. All throat swabs and urine of the infant detected via Real-time Quantitative Polymerase Chain Reaction (RT-PCR) were negative, but his anal swab continued to test positive up to 40 days after onset of illness. Our study indicated that infants infected with COVID-19 may have relatively mild symptoms or clinical signs, IL-17A, IL-17 F, and TNF-α could be involved in the immune response of COVID-19. In addition, severe acute respiratory syndrome coronavirus 2(SARS-CoV-2) may shed through the gastrointestinal tract and convalescent carriers may exist among infant patients. We cannot rule out the possibility that infants may acquire infection from breastfeeding. Intensive care and nutrition support are recommended for infant patients with mild symptoms.

TEAD4 transcriptional regulates SERPINB3/4 and affect crosstalk between keratinocytes and T cells in psoriasis.

Psoriasis is a common chronic inflammatory disease with the prevalence rate of approximately 1-3 %. Currently, it is generally believed that the pathogenesis of psoriasis is a T-cell immune-mediated skin disease mediated by multiple genes and factors, and the interaction between keratinocytes and T cells. TEA domain family member 4 (TEAD4) is a transcription factor which regulates the expression of downstream genes in Hippo pathway and affects several biological processes, such as regulating cell differentiation and embryonic development. However, few studies have reported the role of TEAD4 in psoriasis and its possible regulatory mechanism. In this study, we found the expression level of TEAD4 in the skin of psoriasis was significantly higher than that of normal skin. In patients with the pathological keratinocytes, TEAD4 can transcriptionally regulate the expression of SERPINB3/4 and affect the secretion of chemokines, and the depletion of SERPINB3/4 inhibited the secretion of chemokines. In addition, the supernatant of keratinocytes of patients can significantly increase the migration ability of T cells, and the supernatant of T cells cultured by the supernatant of keratinocytes of patients can significantly enhance the proliferation ability of keratinocytes. Therefore, our results suggested that TEAD4 is a key regulatory factor in progression of psoriasis, and the crosstalk between keratinocytes and T cells mediated by TEAD4 plays a critical role in the psoriasis pathogenesis.

The evidence of indirect transmission of SARS-CoV-2 reported in Guangzhou, China.

BACKGROUND: More than 2 months have passed since the novel coronavirus disease 2019 (COVID-19) first emerged in Wuhan, China. With the migration of people, the epidemic has rapidly spread within China and throughout the world. Due to the severity of the epidemic, undiscovered transmission of COVID-19 deserves further investigation. The aim of our study hypothesized possible modes of SARS-CoV-2 transmission and how the virus may have spread between two family clusters within a residential building in Guangzhou, China. METHODS: In a cross-sectional study, we monitored and traced confirmed patients and their close contacts from January 11 to February 5, 2020 in Guangzhou, China, including 2 family cluster cases and 61 residents within one residential building. The environmental samples of the building and the throat swabs from the patients and from their related individuals were collected for SARS-CoV-2 and tested with real-time reverse transcriptase polymerase chain reaction (RT-PCR). The relevant information was collected and reported using big data tools. RESULTS: There were two notable family cluster cases in Guangzhou, which included 3 confirmed patients (family No.1: patient A, B, C) and 2 confirmed patients (family No.2: patient D, E), respectively. None of patients had contact with other confirmed patients before the onset of symptoms, and only patient A and patient B made a short stop in Wuhan by train. Home environment inspection results showed that the door handle of family No.1 was positive of SARS-CoV-2. The close contacts of the 5 patients all tested negative of SARS-CoV-2 and in good health, and therefore were released after the official medical observation period of 14-days. Finally, according to the traceability investigation through applying big data analysis, we found an epidemiological association between family No.1 and family No.2, in which patient D (family No.2) was infected through touching an elevator button contaminated by snot with virus from patient A (family No.1) on the same day. CONCLUSIONS: Contaminants with virus from confirmed patients can pollute the environment of public places, and the virus can survive on the surface of objects for a short period of time. Therefore, in addition to the conventional droplet transmission, there is also indirect contact transmission such as snot-oral transmission that plays a crucial role in community spread of the virus.