A review of emerging health threats from zoonotic New World mammarenaviruses

Despite repeated spillover transmission and their potential to cause significant morbidity and mortality in human hosts, the New World mammarenaviruses remain largely understudied. These viruses are endemic to South America, with animal reservoir hosts covering large geographic areas and whose transmission ecology and spillover potential are driven in part by land use change and agriculture that put humans in regular contact with zoonotic hosts.We compiled published studies about Guanarito virus, Junin virus, Machupo virus, Chapare virus, Sabia virus, and Lymphocytic Choriomeningitis virus to review the state of knowledge about the viral hemorrhagic fevers caused by New World mammarenaviruses. We summarize what is known about rodent reservoirs, the conditions of spillover transmission for each of these pathogens, and the characteristics of human populations at greatest risk for hemorrhagic fever diseases. We also review the implications of repeated outbreaks and biosecurity concerns where these diseases are endemic, and steps that countries can take to strengthen surveillance and increase capacity of local healthcare systems. While there are unique risks posed by each of these six viruses, their ecological and epidemiological similarities suggest common steps to mitigate spillover transmission and better contain future outbreaks.

Building parameters linked with indoor transmission of SARS-CoV-2

The rapid spread of Coronavirus Disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has emphasized the importance of understanding and adapting to the indoor remediation of transmissible diseases to decrease the risk for future pandemic threats. While there were many precautions in place to hinder the spread of COVID-19, there has also been a substantial increase of new research on SARS-CoV-2 that can be utilized to further mitigate the transmission risk of this novel virus. This review paper aims to identify the building parameters of indoor spaces that could have considerable influence on the transmission of SARS-CoV-2. The following building parameters have been identified and analyzed, emphasizing their link with the indoor transmission of SARS-CoV-2: temperature and relative humidity, temperature differences between rooms, ventilation rate and access to natural ventilation, occupant density, surface type and finish, airflow direction and speed, air stability, indoor air pollution, central air conditioning systems, capacity of air handling system and HVAC filter efficiency, edge sealing of air filters, room layout and interior design, and compartmentalization of interior space. This paper also explains the interactions of SARS-CoV-2 with indoor environments and its persistence. Furthermore, the modifications of the key building parameters have been discussed for controlling the transmission of SARS-CoV-2 in indoor spaces. Understanding the information provided in this paper is crucial to develop effective health and safety measures that will aid in infection prevention.

Epidemiology and transmission of hepatitis A in Shaanxi (western China) after more than ten years of universal vaccination

Background

Hepatitis A (HepA) vaccination and economic factors can change the epidemiology of HepA. In China, the implementation of free vaccination for children under 1.5 years of age in 2008 has resulted in a decline in the overall incidence of HepA. Nevertheless, further investigation is required to comprehensively understand the epidemiological patterns of HepA in economically disadvantaged regions of China.

Method

In this study, we evaluated the incidence, seroprevalence, and transmission characteristics of HepA in Shaanxi with less economically developed. We obtained data on reported cases of HepA from 2005 to 2020. Blood samples from 1,559 individuals aged 0 to 60 years were tested for anti-hepatitis A (HAV) antibodies. A questionnaire survey and blood sample collection were conducted in two sentinel sites from 2019 to 2021.

Result

Between 2008 to 2020, the number of reported cases of HepA decreased from 3.44/100,000 person-years to 0.65/100,000 person-years, indicating an 81.1% decrease, which was particularly pronounced among younger age groups (0-19 years). From 2015-2020, infections were more likely to occur in people in their 40s and those over the age of 60. Farmers were still the most common occupation of HepA in the last decade. The results of the serological investigation showed the highest anti-HAV seroprevalence was observed in adults aged 39-60 years (94.6%) and those aged 28-38 years (87.8%). The 10-15 years group had the lowest seroprevalence at 49.3%. During the study period, a total of 22 cases were reported by sentinel sites, but the common risk factors (like raw food exposure, travel history, and closed contact with patients) were not identified.

Conclusion

Given the greater severity of illness in the adult population and the ambiguous transmission routine, enhanced surveillance for HepA and evaluations that identify feasible approaches to mitigate the risk of HAV transmission are urgent priorities.

Transmission risk assessment of HIV/AIDS epidemic resulting from sexual transmission in China, 2013-2017

To estimate the risk of human immunodeficiency virus (HIV) infection through sexual transmission in China from 2013 to 2017 accurately, we divide the total population into three groups, namely, men who have sex with men (MSM) group; non-marital and commercial sex group: female sex workers (FSW) and their clients (FSWC); non-marital and non-commercial sex group: general women (GW) and general men (GM). First, the risks of HIV infection among men who have contacts with infected men or infected women decrease annually. Second, the number of contacts between susceptible FSWC and infected FSW per unit time is greater than that between susceptible MSM and infected MSM, and also greater than that between susceptible FSW and infected FSWC, which suggests that the intervention for commercial sex of heterosexual men should be strengthened. Third, the effective reproduction numbers of the MSM group and non-commercial sex group decrease annually, while the effective reproduction number of the commercial sex group decreases first, then increases, because the risk of women being infected by men decreases first, then increases. Additionally, the effective reproduction number of the commercial sex group exceeds that of the MSM group after 2015, which indicates that commercial sex contributes more and more to the HIV/AIDS epidemic.

Monitoring the dynamics of consumption of ungulate game by-products in vulture feeding stations in Iberian Mediterranean ecosystems

Vulture feeding stations (VFS) are strategic sites for the management of ungulate game by-products, with major implications for the conservation of obligate avian scavengers. These feeding points are designed to prevent access by facultative mammalian scavengers and to reduce the risk of trophically transmitted pathogen infection through scavenging behaviour. The aim of this study, using camera trap video recordings, was to evaluate the feeding dynamics around 32 lots of ungulate game by-products deposited in VFS in southern Spain. During the study period (2017-2022), 11 different avian and mammal scavenger species was detected. Also, many feeding events involving all scavenger species (51.1%; 362/709) and mammal scavenger species (23.4%; 166/709) was recorded. A significantly earlier presence of major obligate scavengers (Gyps fulvus and Aegypius monachus) (P = 0.023) and a lower persistence of by-products deposited (P < 0.001) were detected during October-December compared to January-March. Our results confirm that VFS play an important role in vulture conservation in Iberian Mediterranean ecosystems. However, we also point out the potential risk of VFS as hotspots of foodborne pathogens for mammal scavengers, particularly when the hunting offal persists longer. Consequently, we urge the competent authorities to update the regulations affecting VFS management, and hunting estate managers to make every effort to correctly apply those preventing scavenging mammals from gaining access to VFS. Further studies tackling access of non-target species to VFS are also warranted to properly assess the sanitary implications and geographical extent of these problems for mammal species inhabiting areas where VFS are installed.

Molecular Identification and Genetic Characterization of Public Health Threatening Ticks - Chongming Island, China, 2021-2022

What is already known about this topic?

Although ticks and tick-borne diseases are prevalent throughout China, there remains a knowledge gap regarding their biology and potential risk of distribution to human and animal populations on Chongming Island. The island, being China's third largest and a crucial component in the ecological preservation of the Yangtze Delta region, has yet to be comprehensively studied in this context.

What is added by this report?

In this study, employing molecular methodologies, a significant prevalence of Haemaphysalis (H.) longicornis and H. flava ticks - widely recognized for their high pathogenicity - is reported from Chongming Island. Additionally, the identification of two previously unreported species on the island, namely, H. doenitzi and H. japonica, expands our understanding of both the range and evolution of tick species.

What are the implications for public health practice?

The populations of humans and animals in nearly all 18 towns on Chongming Island are potentially at risk for transmission of tick-borne infectious agents. As a result, there is a pressing necessity for public health alerts, proactive tick surveillance, and effective screening of suspected clinical cases of tick-borne diseases within the Chongming population.

Mapping global zoonotic niche and interregional transmission risk of monkeypox: a retrospective observational study

BACKGROUND

Outbreaks of monkeypox have been ongoing in non-endemic countries since May 2022. A thorough assessment of its global zoonotic niche and potential transmission risk is lacking.

METHODS

We established an integrated database on global monkeypox virus (MPXV) occurrence during 1958 - 2022. Phylogenetic analysis was performed to examine the evolution of MPXV and effective reproductive number (Rt) was estimated over time to examine the dynamic of MPXV transmissibility. The potential ecological drivers of zoonotic transmission and inter-regional transmission risks of MPXV were examined.

RESULTS

As of 24 July 2022, a total of 49 432 human patients with MPXV infections have been reported in 78 countries. Based on 525 whole genome sequences, two main clades of MPXV were formed, of which Congo Basin clade has a higher transmissibility than West African clade before the 2022-monkeypox, estimated by the overall Rt (0.81 vs. 0.56), and the latter significantly increased in the recent decade. Rt of 2022-monkeypox varied from 1.14 to 4.24 among the 15 continuously epidemic countries outside Africa, with the top three as Peru (4.24, 95% CI: 2.89-6.71), Brazil (3.45, 95% CI: 1.62-7.00) and the United States (2.44, 95% CI: 1.62-3.60). The zoonotic niche of MPXV was associated with the distributions of Graphiurus lorraineus and Graphiurus crassicaudatus, the richness of Rodentia, and four ecoclimatic indicators. Besides endemic areas in Africa, more areas of South America, the Caribbean States, and Southeast and South Asia are ecologically suitable for the occurrence of MPXV once the virus has invaded. Most of Western Europe has a high-imported risk of monkeypox from Western Africa, whereas France and the United Kingdom have a potential imported risk of Congo Basin clade MPXV from Central Africa. Eleven of the top 15 countries with a high risk of MPXV importation from the main countries of 2022-monkeypox outbreaks are located at Europe with the highest risk in Italy, Ireland and Poland.

CONCLUSIONS

The suitable ecological niche for MPXV is not limited to Africa, and the transmissibility of MPXV was significantly increased during the 2022-monkeypox outbreaks. The imported risk is higher in Europe, both from endemic areas and currently epidemic countries. Future surveillance and targeted intervention programs are needed in its high-risk areas informed by updated prediction.

DNA sequencing confirms meningeal worm (Parelaphostrongylus tenuis) and muscle worm (Parelaphostrongylus andersoni) in white-tailed deer (Odocoileus virginianus): Implications for moose (Alces alces) management

In North America, some moose populations are declining, and meningeal worm (Parelaphostrongylus tenuis) infections may be contributing. Moose are aberrant hosts for meningeal worm and develop severe pathology whereas white-tailed deer (WTD) are definitive hosts that experience minimal pathology and spread parasite larvae into the environment. Analyses of harvested WTD heads confirmed meningeal worm in Western Manitoba, Canada including in areas where moose have experienced population declines and are currently of management concern. The prevalence of larval meningeal worm from WTD feces in these areas are unknown, particularly because the dorsal-spined larvae (DSL) are morphologically indistinguishable from muscle worm (Parelaphostrongylus andersoni). To assess transmission risk of DSL, we investigated the spatial and temporal variation of prevalence in WTD feces from four areas (two with historical moose population declines and two without) sampled across two summers. We predicted higher prevalence of DSL in areas where moose are of management concern and surveys have shown higher meningeal worm prevalence in WTD heads. Further, we expected to only recover meningeal worm, as muscle worm has only been reported from caribou in more northern areas of Manitoba. We collected WTD feces by transect sampling, used the Baermann technique to obtain larvae, and sequenced partial cytochrome oxidase 1 and internal transcribed spacer 2 genes to confirm species identity. Zero-inflated models revealed that DSL prevalence did not differ temporally but was higher in areas where moose are of management concern. Genetic analyses revealed that meningeal worm and muscle worm were both present in Western Manitoba and co-occurred in three areas. Our results reveal novel insights into the geographic distribution of muscle worm and emphasize the importance of DNA sequencing for DSL identification. We suggest that concern for moose populations is warranted given the increased risk of parasite infection in some management areas.

Influence of setting-dependent contacts and protective behaviours on asymptomatic SARS-CoV-2 infection amongst members of a UK university

We survey 62 users of a university asymptomatic SARS-CoV-2 testing service on details of their activities, protective behaviours and contacts in the 7 days prior to receiving a positive or negative SARS-CoV-2 PCR test result in the period October 2020-March 2021. The resulting data set is novel in capturing very detailed social contact history linked to asymptomatic disease status during a period of significant restriction on social activities. We use this data to explore 3 questions: (i) Did participation in university activities enhance infection risk? (ii) How do contact definitions rank in their ability to explain test outcome during periods of social restrictions? (iii) Do patterns in the protective behaviours help explain discrepancies between the explanatory performance of different contact measures? We classify activities into settings and use Bayesian logistic regression to model test outcome, computing posterior model probabilities to compare the performance of models adopting different contact definitions. Associations between protective behaviours, participant characteristics and setting are explored at the level of individual activities using multiple correspondence analysis (MCA). We find that participation in air travel or non-university work activities was associated with a positive asymptomatic SARS-CoV-2 PCR test, in contrast to participation in research and teaching settings. Intriguingly, logistic regression models with binary measures of contact in a setting performed better than more traditional contact numbers or person contact hours (PCH). The MCA indicates that patterns of protective behaviours vary between setting, in a manner which may help explain the preference for any participation as a contact measure. We conclude that linked PCR testing and social contact data can in principle be used to test the utility of contact definitions, and the investigation of contact definitions in larger linked studies is warranted to ensure contact data can capture environmental and social factors influencing transmission risk.

Gastrointestinal Endoscopy in Patients with Coronavirus Disease 2019: Indications, Findings, and Safety

The coronavirus disease 2019 (COVID-19) pandemic has changed the practice of gastroenterology and how we perform endoscopy. As with any new or emerging pathogen, early in the pandemic, there was limited evidence and understanding of disease transmission, limited testing capability, and resource constraints, especially availability of personal protective equipment (PPE). As the COVID-19 pandemic progressed, enhanced protocols with particular emphasis on assessing the risk status of patients and proper use of PPE have been incorporated into routine patient care. The COVID-19 pandemic has taught us important lessons for the future of gastroenterology and endoscopy.

Person-time spent with HIV viral load above 1500 copies/mL among Miami-Dade County Ryan White Program clients, 2017-2019: a retrospective analysis

HIV transmission risk significantly increases at HIV viral load (VL) >1500 copies/mL. We sought to determine the percentage of person-time spent with VL >1500 copies/mL (pPT >1500) and the associations of demographic, clinical, and psychosocial factors and this outcome among persons with HIV receiving care. A retrospective analysis of data from clients enrolled in the Ryan White Program from 2017 to 2019 was performed. We assessed pPT >1500 in HIV care by utilizing consecutive VL pairs and calculating the length of time between each pair and the corresponding time spent for the observation period. The association between pPT >1500 and selected client characteristics were analyzed using a random-effects zero-inflated negative binomial model. Among the 6390 clients, 42% were aged 50 or older, 52% MSM, and 59% Hispanic. Overall, 7.5% of clients spent, on average, 27.4 days per year at substantial risk of transmitting HIV. Younger age, AIDS diagnosis, and reported drug use in the preceding 12 months were associated with higher pPT >1500. Tailored interventions should be implemented to meet the unique HIV needs of groups with consistent viremia to significantly minimize transmission risk.

Establishment of an indicator framework for the transmission risk of the mountain-type zoonotic visceral leishmaniasis based on the Delphi-entropy weight method

BACKGROUND

Visceral leishmaniasis (VL) is one of the most important neglected tropical diseases. Although VL was controlled in several regions of China during the last century, the mountain-type zoonotic visceral leishmaniasis (MT-ZVL) has reemerged in the hilly areas of China in recent decades. The purpose of this study was to construct an indicator framework for assessing the risk of the MT-ZVL in China, and to provide guidance for preventing disease.

METHODS

Based on a literature review and expert interview, a 3-level indicator framework was initially established in November 2021, and 28 experts were selected to perform two rounds of consultation using the Delphi method. The comprehensive weight of the tertiary indicators was determined by the Delphi and the entropy weight methods.

RESULTS

Two rounds of Delphi consultation were conducted. Four primary indicators, 11 secondary indicators, and 35 tertiary indicators were identified. The Delphi-entropy weight method was performed to calculate the comprehensive weight of the tertiary indicators. The normalized weights of the primary indicators were 0.268, 0.261, 0.242, and 0.229, respectively, for biological factors, interventions, environmental factors, and social factors. The normalized weights of the top four secondary indicators were 0.122, 0.120, 0.098, and 0.096, respectively, for climatic features, geographical features, sandflies, and dogs. Among the tertiary indicators, the top four normalized comprehensive weights were the population density of sandflies (0.076), topography (0.057), the population density of dogs, including tethering (0.056), and use of bed nets or other protective measures (0.056).

CONCLUSIONS

An indicator framework of transmission risk assessment for MT-ZVL was established using the Delphi-entropy weight method. The framework provides a practical tool to evaluate transmission risk in endemic areas.

Antibiotic resistance, virulence and genetic characteristics of Vibrio alginolyticus isolates from aquatic environment in costal mariculture areas in China

Vibrio alginolyticus has been the second most common Vibrio species in the world and mainly grows in the ocean or estuary environment, which can induce epidemics outbreaks under marine organisms, and causing serious economic losses in aquaculture industry. In this study, the genetic populations and evolutionary relationship analysis of V. alginolyticus isolated from different geographical locations in China with typical interannual differences were exhibited originally genetic diversity. Then the virulence genes prevalence, antibiotic resistance phenotype, and antimicrobial resistance genes risk diversity of V. alginolyticus were analyzed by phenotypic and molecular typing methods. And they were complex correlations among antibiotic phenotypes, resistance and virulence genes under different genotype of V. alginolyticus. The results provide a theoretical foundation for further understanding the genetic and metabolic diversity among V. alginolyticus in China, and lay a theoretical foundation for the transmission risk assessment and regional diagnosis of Vibrio in aquatic animals.

Transmission and mortality risk assessment of severe fever with thrombocytopenia syndrome in China: results from 11-years' study

Background

The transmission and fatal risk of severe fever with thrombocytopenia syndrome (SFTS), an emerging infectious disease first discovered in China in 2009, still needed further quantification. This research aimed to analyze the SFTS clusters and assess the transmission and mortality risk for SFTS.

Methods

Both epidemiological investigation and case reports regarding SFTS clusters in China during 2011–2021 were obtained from the Public Health Emergency Information Management System of the Chinese Center for Disease Control and Prevention Information System. The transmission risk was evaluated by using the secondary attack rate (SAR) and relative risk (RR). Mortality risk factors were analyzed using a logistic regression model.

Results

There were 35 SFTS clusters during 2011–2021 involving 118 patients with a fatality rate of 22.0%. The number of clusters annually increased seasonally from April to September. The clusters mainly occurred in Anhui (16 clusters) and Shandong provinces (8 clusters). The SAR through contact with blood or bloody fluids was much higher than that through contact with non-bloody fluids (50.6% vs 3.0%; χ² = 210.97, P < 0.05), with an RR of 16.61 [95% confidence interval (CI): 10.23–26.97]. There was a statistically significant difference in the SAR between exposure to the blood of a deceased person during burial preparation and exposure to the living patients’ blood (66.7% vs 34.5%; χ² = 6.40, P < 0.05), with an RR of 1.93 (95% CI: 1.11–3.37). The mortality risk factors were a long interval from onset to diagnosis [odds ratio (OR) = 1.385), 95% CI: 1.083–1.772, P = 0.009) and advanced age (OR: 1.095, 95% CI: 1.031–1.163, P = 0.01).

Conclusions

The SFTS clusters showed a high mortality rate and resulted in a high SAR. Contact with a bleeding corpse was associated with a higher infection risk, compared with contacting the blood from living patients. It is important to promote early detection and appropriate case management of patients with SFTS, as well as improved handling of their corpses, to prevent further transmission and mortality.

Graphical abstract

Impact of the surrounding environment on antibiotic resistance genes carried by microplastics in mangroves

The pollution of antibiotic resistance genes (ARGs) carried by microplastics (MPs) is a growing concern. Mangroves are located at the intersection of land and sea and are seriously affected by MP pollution. However, few studies have systematic research evaluating the transmission risk of ARGs carried by MPs in mangroves. We conducted in situ experiments by burying five different MPs (polypropylene, high-density polyethylene, polystyrene, polyethylene glycol terephthalate, and polycaprolactone particles) in mangroves with different surrounding environments. A total of 10 genes in the MPs of mangroves were detected using quantitative real-time polymerase chain reactions, including eight ARGs and two mobile genetic elements (MGEs). The abundance of ARGs in Guanhai park mangroves in living areas (GH) was higher than that of Gaoqiao mangroves in protected areas (GQ) and Beiyue dike mangroves in aquaculture pond areas (BY). Pathogenic bacteria, such as Acinetobacter, Bacillus, and Vibrio were found on the MP surfaces of the mangroves. The number of ARGs carried by multiple drug-resistant bacteria in the GH mangroves was greater than that in the GQ and BY mangroves. Moreover, the ARGs carried by MPs in GH mangroves had the highest potential transmission risk by horizontal gene transfer. Sociometric and environmental factors were the main drivers shaping the distribution characteristics of ARGs and MGEs. Polypropylene and high-density polyethylene particles are preferred substrates for obtaining diffuse ARGs. This study investigated the drivers of ARGs in the MPs of mangroves and provided essential guidance on the use and handling of plastics.

Transmission of SARS-CoV-2 on Cold-Chain Food: Precautions Can Effectively Reduce the Risk

The COVID-19 pandemic has generated a new era in the world, also in the food safety. Up to now, there is no evidence to suggest that people can infect COVID-19 via food contaminated by SARS-CoV-2. Here, we analyzed the results of regular SARS-CoV-2 nucleic acid testing of considerable cold-chain food practitioners, cold-chain food surfaces, and their internal or external packaging as well as their associated environments, aiming to explore the risk of cold-chain food being contaminated by SARS-CoV-2 and the probability of people infecting COVID-19 through contaminated cold-chain food in the context of COVID-19 epidemic. This study found that only two batches of cold-chain food were contaminated by SARS-CoV-2, none of the cold-chain food handler were infected due to effective regulatory measures for cold-chain food. Therefore, effective supervision and preventive methods could effectively reduce the transmission risk of SARS-CoV-2 on cold-chain food.

A population framework for predicting the proportion of people infected by the far-field airborne transmission of SARS-CoV-2 indoors

The number of occupants in a space influences the risk of far-field airborne transmission of SARS-CoV-2 because the likelihood of having infectious and susceptible people both correlate with the number of occupants. This paper explores the relationship between occupancy and the probability of infection, and how this affects an individual person and a population of people. Mass-balance and dose-response models determine far-field transmission risks for an individual person and a population of people after sub-dividing a large reference space into 10 identical comparator spaces. For a single infected person, the dose received by an individual person in the comparator space is 10 times higher because the equivalent ventilation rate per infected person is lower when the per capita ventilation rate is preserved. However, accounting for population dispersion, such as the community prevalence of the virus, the probability of an infected person being present and uncertainty in their viral load, shows the transmission probability increases with occupancy and the reference space has a higher transmission risk. Also, far-field transmission is likely to be a rare event that requires a high emission rate, and there are a set of Goldilocks conditions that are just right when equivalent ventilation is effective at mitigating against transmission. These conditions depend on the viral load, because when they are very high or low, equivalent ventilation has little effect on transmission risk. Nevertheless, resilient buildings should deliver the equivalent ventilation rate required by standards as minimum.

Molecular evidence on the presence of Schistosoma japonicum infection in snails along the Yangtze River, 2015-2019

Background

Due to sustained control activities, the prevalence of Schistosoma japonicum infection in humans, livestock and snails has decreased significantly in P. R. China, and the target has shifted from control to elimination according to the Outline of Healthy China 2030 Plan. Applying highly sensitive methods to explore the presence of S. japonicum infection in its intermediate host will benefit to assess the endemicity or verify the transmission interruption of schistosomiasis accurately. The aim of this study was to access the presence of S. japonicum infection by a loop-mediated isothermal amplification (LAMP) method through a 5-year longitudinal study in five lake provinces along the Yangtze River.

Methods

Based on previous epidemiological data, about 260 villages with potential transmission risk of schistosomiasis were selected from endemic counties in five lake provinces along the Yangtze River annually from 2015 to 2019. Snail surveys were conducted in selected villages by systematic sampling method and/or environmental sampling method each year. All live snails collected from field were detected by microscopic dissection method, and then about one third of them were detected by LAMP method to assess the presence of S. japonicum infection with a single blind manner. The infection rate and nucleic acid positive rate of schistosomes in snails, as well as the indicators reflecting the snails’ distribution were calculated and analyzed. Fisher's exact test was used to examine any change of positive rate of schistosomes in snails over time.

Results

The 5-year survey covered 94,241 ha of environment with 33,897 ha of snail habitats detected accumulatively. Totally 145.3 ha new snail habitats and 524.4 ha re-emergent snail habitats were found during 2015–2019. The percentage of frames with snails decreased from 5.93% [45,152/761,492, 95% confidence intervals (CI): 5.88–5.98%] in 2015 to 5.25% (30,947/589,583, 95% CI: 5.19–5.31%) in 2019, while the mean density of living snails fluctuated but presented a downward trend generally from 0.20 snails/frame (155,622/761,492, 95% CI: 0.17–0.37) in 2015 to 0.13 snails/frame (76,144/589,583, 95% CI: 0.11–0.39) in 2019. A total of 555,393 live snails were collected, none of them was positive by dissection method. Totally 17 pooling snail samples were determined as positives by LAMP method among 8716 pooling samples with 174,822 of living snails, distributed in 12 villages of Hubei, Hunan, Jiangxi and Anhui provinces. The annual average positive rate was 0.41% (95% CI: 0.13–0.69%) in 2015, 0% in 2016, 0.36% (95% CI: 0.09–0.63%) in 2017, 0.05% (95% CI: 0–0.16%) in 2018, 0.05% (95% CI: 0–0.15%) in 2019, respectively, presenting a downward trend from 2015 to 2019 with statistical significance (χ² = 11.64, P < 0.05).

Conclusions

The results suggest that S. japonicum infection still persisted in nature along the Yangtze River and traditional techniques might underestimate the prevalence of schistosomiasis in its intermediate hosts. Exploring and integrating molecular techniques into national surveillance programme could improve the sensitivity of surveillance system and provide guidance on taking actions against schistosomiasis.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s40249-022-00995-9.

Variability in transmission risk of SARS-CoV-2 in close contact settings: A contact tracing study in Shandong Province, China

BACKGROUND

Understanding the relative transmissibility of SARS-CoV-2 virus across different contact settings and the possibility of superspreading events is important for prioritizing disease control. Such assessment requires proper consideration of individual level exposure history, which is made possible by contact tracing.

METHODS

The case-ascertained study in Shandong, China including 97 laboratory-confirmed index cases and 3158 close contacts. All close contacts were quarantined after their last exposure of index cases. Contacts were tested for COVID-19 regularly by PCR to identify both symptomatic and asymptomatic infections. We developed a Bayesian transmission model to the contact tracing data to account for different duration of exposure among individuals to transmission risk in different settings, and the heterogeneity of infectivity of cases.

RESULTS

We estimate secondary attack rates (SAR) to be 39% (95% credible interval (CrI): 20-64%) in households, 30% (95% CrI: 11-67%) in healthcare facilities, 23% (95% CrI: 7-51%) at workplaces, and 4% (95% CrI: 1-17%) during air travel. Models allowing heterogeneity of infectivity of cases provided a better goodness-of-fit. We estimated that 64% (95% CrI: 55-72%) of cases did not generate secondary transmissions, and 20% (95% CrI: 15-26%) cases explained 80% of secondary transmissions.

CONCLUSIONS

Household, healthcare facilities and workplaces are efficient setting for transmission. Timely identification of potential superspreaders in most transmissible settings remains crucial for containing the pandemic.

Occurrence and decay of SARS-CoV-2 in community sewage drainage systems

The rapid spread of the coronavirus disease (COVID-19) pandemic in over 200 countries poses a substantial threat to human health. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes COVID-19, can be discharged with feces into the drainage system. However, a comprehensive understanding of the occurrence, presence, and potential transmission of SARS-CoV-2 in sewers, especially in community sewers, is still lacking. This study investigated the virus occurrence by viral nucleic acid testing in vent stacks, septic tanks, and the main sewer outlets of community where confirmed patients had lived during the outbreak of the epidemic in Wuhan, China. The results indicated that the risk of long-term emission of SARS-CoV-2 to the environment via vent stacks of buildings was low after confirmed patients were hospitalized. SARS-CoV-2 were mainly detected in the liquid phase, as opposed to being detected in aerosols, and its RNA in the sewage of septic tanks could be detected for only four days after confirmed patients were hospitalized. The surveillance of SARS-CoV-2 in sewage could be a sensitive indicator for the possible presence of asymptomatic patients in the community, though the viral concentration could be diluted more than 10 times, depending on the sampling site, as indicated by the Escherichia coli (E. coli) test. The comprehensive investigation of the community sewage drainage system is helpful to understand the occurrence characteristics of SARS-CoV-2 in sewage after excretion with feces and the feasibility of sewage surveillance for COVID-19 pandemic monitoring.

[Potential transmission risk of key parasitic diseases and responses to the risk during the construction of an ecological city in Shanghai Municipality]

A blueprint on Shanghai's ecological space design between 2021 and 2035 was released in 2021, aiming to build an ecological city and improve the development of ecological civilization. The transmission of parasitic diseases is strongly associated with climate and ecological environments. Currently, the prevalence of parasitic diseases has been maintained at extremely low-transmission levels, and there are almost no local cases; however, the alteration of ecological environments may results in a potential transmission risk of parasitic diseases. Hereby, the current status of key parasitic diseases in Shanghai Municipality was described, and the potential transmission risk of parasitic diseases and responses to this risk were analyzed during the construction of an ecological city in Shanghai Municipality. In addition, the suggestions pertaining to surveillance and management of parasitic diseases were proposed during the mid- and long-term construction of an ecological city in Shanghai Municipality.

Aedes aegypti abundance, larval indices and risk for dengue virus transmission in Kinondoni district, Tanzania

BACKGROUND

Tanzania has experienced periodic dengue outbreaks with increased incidence since 2010. However, there is limited information on vector dynamics and transmission risk in most parts of the country. This study was conducted to determine Aedes mosquito abundance, larval indices and dengue virus infection rate as risk indicators for DENV transmission in Kinondoni district, Dar es Salaam, Tanzania.

METHODS

A cross-sectional study was conducted in three wards of Kinondoni district in Tanzania between December 2019 and January 2020. In each ward, three streets were randomly selected for adult and immature mosquito sampling. The adult mosquitoes were collected using Mosquito Magnet traps, while mosquito larvae and pupae were inspected in water-holding containers in the selected household compounds. The detection of dengue virus (DENV) in female Aedes mosquitoes was done using a one-step reverse transcription-polymerase chain reaction (RT-PCR) method.

RESULTS

Of the 1416 adult female mosquitoes collected, Ae. aegypti accounted for 16.8% (n = 238). A total of 333 water-holding containers were inspected and 201 (60.4%) had at least an Aedes larvae or pupae. Water-holding containers supporting the breeding of Aedes larvae and pupae included discarded car tires, flowerpots and small and large plastic containers. The overall House Index, Container Index and Breteau Index were 55.1%, 60.4% and 114.2, respectively. None of the 763 female Aedes mosquitoes tested by RT-PCR was found to be infected with DENV.

CONCLUSION

The presence and abundance Ae. aegypti mosquitoes and the large proportion of water-holding containers infested with the mosquito larvae and pupae put residents of Kinondoni district at high risk of DENV transmission. Our findings emphasize the need for continuous mosquito vector surveillance and control to prevent the possibility of future DENV outbreaks in Tanzania.

Discrimination of non-infectious SARS-CoV-2 particles from fomites by viability RT-qPCR

The ongoing coronavirus 2019 (COVID-19) pandemic constitutes a concerning global threat to public health and economy. In the midst of this pandemic scenario, the role of environment-to-human COVID-19 spread is still a matter of debate because mixed results have been reported concerning SARS-CoV-2 stability on high-touch surfaces in real-life scenarios. Up to now, no alternative and accessible procedures for cell culture have been applied to evaluate SARS-CoV-2 infectivity on fomites. Several strategies based on viral capsid integrity have latterly been developed using viability markers to selectively remove false-positive qPCR signals resulting from free nucleic acids and damaged viruses. These have finally allowed an estimation of viral infectivity. The present study aims to provide a rapid molecular-based protocol for detection and quantification of viable SARS-CoV-2 from fomites based on the discrimination of non-infectious SARS-CoV-2 particles by platinum chloride (IV) (PtCl₄) viability RT-qPCR. An initial assessment compared two different swabbing procedures to recover inactivated SARS-CoV-2 particles from fomites coupled with two RNA extraction methods. Procedures were validated with human (E229) and porcine (PEDV) coronavirus surrogates, and compared with inactivated SARS-CoV-2 suspensions on glass, steel and plastic surfaces. The viability RT-qPCR efficiently removed the PCR amplification signals from heat and gamma-irradiated inactivated SARS-CoV-2 suspensions that had been collected from specified surfaces. This study proposes a rapid viability RT-qPCR that discriminates non-infectious SARS-CoV-2 particles on surfaces thus helping researchers to better understand the risk of contracting COVID-19 through contact with fomites and to develop more efficient epidemiological measures.

Should bike-sharing continue operating during the COVID-19 pandemic? Empirical findings from Nanjing, China

INTRODUCTION

Coronavirus disease 2019 (COVID-19) has triggered a worldwide outbreak of pandemic, and transportation services have played a key role in coronavirus transmission. Although not crowded in a confined space like a bus or a metro car, bike-sharing users are exposed to the bike surface and take the transmission risk. During the COVID-19 pandemic, how to meet user demand and avoid virus spreading has become an important issue for bike-sharing.

METHODS

Based on the trip data of bike-sharing in Nanjing, China, this study analyzes the travel demand and operation management before and after the pandemic outbreak from the perspectives of stations, users, and bikes. Semi-logarithmic difference-in-differences model, visualization methods, and statistic indexes are applied to explore the transportation service and risk prevention of bike-sharing during the pandemic.

RESULTS

Pandemic control strategies sharply reduced user demand, and commuting trips decreased more significantly. Some stations around health and religious places become more important. Men and older adults may be more dependent on bike-sharing systems. The declined trips reduce user contacts and transmission risk. Central urban areas have more user close contacts and higher transmission risk than suburban areas. Besides, a new concept of user distancing is proposed to decrease transmission risk and the number of idle bikes.

CONCLUSIONS

This paper is the first research focusing on both user demand and transmission risk of bike-sharing during the COVID-19 pandemic. This study evaluates the mobility role of bike-sharing during the COVID-19 pandemic, and also provides insights into curbing the viral transmission within the city.

Transmission risks of respiratory infectious diseases in various confined spaces: A meta-analysis for future pandemics

BACKGROUND

If the different transmission risks of respiratory infectious diseases according to the type of confined space and associated factors could be discovered, this kind of information will be an important basis for devising future quarantine policies. However, no comprehensive systematic review or meta-analysis for this topic exists.

OBJECTIVE

The objective of this study is to analyze different transmission risks of respiratory infectious diseases according to the type of confined space. This information will be an important basis for devising future quarantine policies.

METHODS

A medical librarian searched MEDLINE, EMBASE, and the Cochrane Library (until December 01, 2020).

RESULTS

A total of 147 articles were included. The risk of transmission in all types of confined spaces was approximately 3 times higher than in open space (combined RR, 2.95 (95% CI 2.62-3.33)). Among them, school or workplace showed the highest transmission risk (combined RR, 3.94 (95% CI 3.16-4.90)). Notably, in the sub-analysis for SARS-CoV-2, residential space and airplane were the riskiest space (combined RR, 8.30 (95% CI 3.30-20.90) and 7.30 (95% CI 1.15-46.20), respectively).

DISCUSSION

Based on the equation of the total number of contacts, the order of transmission according to the type of confined space was calculated. The calculated order was similar to the observed order in this study. The transmission risks in confined spaces can be lowered by reducing each component of the aforementioned equation. However, as seen in the data for SARS-CoV-2, the closure of one type of confined space could increase the population density in another confined space. The authority of infection control should consider this paradox. Appropriate quarantine measures targeted for specific types of confined spaces with a higher risk of transmission, school or workplace for general pathogens, and residential space/airplane for SARS-CoV-2 can reduce the transmission of respiratory infectious diseases.

[Progress of researches on the diagnostic techniques for schistosomiasis]

Schistosomiasis is an important zoonotic parasitic disease, and is categorized as a neglected tropical disease by the World Health Organization. Following the concerted efforts for more than 70 years, great achievements have been made in the national schistosomiasis control program in China, and the prevalence, disability and mortality due to schistosomiasis has remarkably dropped. Nevertheless, the frequent identification of imported schistosomiasis and the resulting potential transmission risk in mainland China have been recently paid much attention following the implementation of the "Belt and Road Initiative" and the China-Africa Cooperation Forum. This review describes the advances in the diagnostic tools for schistosomiasis, including pathogenic techniques, immunodiagnostic techniques and nucleic acid assays, in order to consolidate schistosomiasis control achievements and promote the capability for detection of external biological safety risks.

A Prospective Study of Depressive Symptoms, Condomless Sex, and HIV Viral Load in HIV-Positive Female Sex Workers in Kenya

The relationships between depressive symptoms, viral suppression, and condomless sex were examined in a prospective cohort study of 369 HIV-positive Kenyan female sex workers. Participants were screened for depressive symptoms at baseline and every six months until completion of the study (up to 66 months). HIV viral load (VL) was measured every six months and prostate specific antigen (PSA) testing in vaginal secretions was performed quarterly. Mild or greater depressive symptoms were found in 100 (27.1%) women and were associated with increased risk of detectable VL (aRR 1.41, 95%CI 0.97-2.07, p-value = 0.07), but were not associated with detectable PSA. The co-occurrence of PSA detection and detectable VL at the same visit suggests the potential for HIV transmission but was uncommon (2.4% of visits). The prevalence of depressive symptoms and the association with detectable VL suggests the need for screening and treatment of depression for comprehensive HIV care in this population.

[Progress of researches on the application of risk assessment models in assessment of the schistosomiasis transmission risk]

With the deepening of the schistosomiasis research, risk assessment models have been widely used in schistosomiasis research and control. This paper reviews the theoretical basis and applications of common schistosomiasis risk assessment models and the Bayesian model, so as to provide insights into national schistosomiasis elimination program in China.

Identifying the space-time patterns of COVID-19 risk and their associations with different built environment features in Hong Kong

Identifying the space-time patterns of areas with a higher risk of transmission and the associated built environment and demographic characteristics during the COVID-19 pandemic is critical for developing targeted intervention measures in response to the pandemic. This study aims to identify areas with a higher risk of COVID-19 transmission in different periods in Hong Kong and analyze the associated built environment and demographic factors using data of individual confirmed cases. We detect statistically significant space-time clusters of COVID-19 at the Large Street Block Group (LSBG) level in Hong Kong between January 23 and April 14, 2020. Two types of high-risk areas are identified (residences of and places visited by confirmed cases) and two types of cases (imported and local cases) are considered. The demographic and built environment features for the identified high-risk areas are further examined. The results indicate that high transport accessibility, dense and high-rise buildings, a higher density of commercial land and higher land-use mix are associated with a higher risk for places visited by confirmed cases. More green spaces, higher median household income, lower commercial land density are linked to a higher risk for the residences of confirmed cases. The results in this study not only can inform policymakers to improve resource allocation and intervention strategies but also can provide guidance to the public to avoid conducting high-risk activities and visiting high-risk places.

An assessment of outpatient clinic room ventilation systems and possible relationship to disease transmission

BACKGROUND

With healthcare shifting to the outpatient setting, this study examined whether outpatient clinics operating in business occupancy settings were conducting procedures in rooms with ventilation rates above, at, or below thresholds defined in the American National Standards Institute/American Society of Heating, Refrigerating and Air-Conditioning Engineers/American Society for Health Care Engineering Standard 170 for Ventilation in Health Care Facilities and whether lower ventilation rates and building characteristics increase the risk of disease transmission.

METHODS

Ventilation rates were measured in 105 outpatient clinic rooms categorized by services rendered. Building characteristics were evaluated as determinants of ventilation rates, and risk of disease transmission was estimated using the Gammaitoni-Nucci model.

RESULTS

When compared to Standard 170, 10% of clinic rooms assessed did not meet the minimum requirement for general exam rooms, 39% did not meet the requirement for treatment rooms, 83% did not meet the requirement for aerosol-generating procedures, and 88% did not meet the requirement for procedure rooms or minor surgical procedures.

CONCLUSIONS

Lower than standard air changes per hour were observed and could lead to an increased risk of spread of diseases when conducting advanced procedures and evaluating persons of interest for emerging infectious diseases. These findings are pertinent during the SARS-CoV-2 pandemic, as working guidelines are established for the healthcare community.

Study on the decay characteristics and transmission risk of respiratory viruses on the surface of objects

The complex and changeable environment is a brand-new living condition for the viruses and pathogens released by the infected people to the indoor air or deposited on the surface of objects, which is an important external condition affecting the decay and transmission risk of the viruses. Exposure to contaminated surfaces is one of the main routes of respiratory diseases transmission. Therefore, it is very important for epidemic prevention and control to study the law of virus decay and the environmental coupling effect on various surfaces. Based on the analysis of the influencing mechanism, a large amount of experimental evidence on the survival of viruses on the surface of objects were excavated in this paper, and the effects of various factors, such as surface peripheral temperature, relative humidity, virus-containing droplet volume, surface materials and virus types, on the decay rate constants of viruses were comprehensively analyzed. It was found that although the experimental methods, virus types and experimental conditions varied widely in different experiments, the virus concentrations on the surface of objects all followed the exponential decay law, and the coupling effect of various factors was reflected in the decay rate constant k. Under different experimental conditions, k values ranged from 0.001 to 100 h^-1, with a difference of 5 orders of magnitude, corresponding to the characteristic time t₉₉ between 500 and 0.1 h when the virus concentration decreased by 99%. This indicates a large variation in the risk of virus transmission in different scenarios. By revealing the common law and individuality of the virus decay on the surface of objects, the essential relationship between the experimental observation phenomenon and virus decay was analyzed. This paper points out the huge difference in virus transmission risk on the surface at different time nodes, and discusses the prevention and control strategies to grasp the main contradictions in the different situations.

Transmission risk of viruses in large mucosalivary droplets on the surface of objects: A time-based analysis

The novel human coronavirus SARS-CoV-2 has been responsible for a worldwide pandemic. Although media transmission through contaminated surfaces is one of the most recognized ways of transmission, the study on the number and viability of viruses surviving on a surface after leaving the host represents a “blind spot” in current research. In this paper we have reviewed studies on the physical process of droplet evaporation on media surfaces, and analyzed the recent literature related to experiments on the decay of the viral concentration and infectious activity of SARS-CoV-2 and other viruses on those surface and in the air. The huge differences in the risk of media transmission of large saliva and sputum droplets were analyzed in terms of time elapsed. Due to the rapid decrease of water content in the evaporated droplets and the increased concentration of each component, the living environment of the virus tended to deteriorate sharply, and virus concentration plummeted within a few minutes. Although a virus can be detected in a matter of hours, tens of hours, or days, the risk of transmission is negligible compared to when it first left the host. This study suggests that the key to prevention and control is to start from the source, the earlier the better. It is extremely important to develop good public health habits, wear masks, and wash hands frequently. That said, excessive disinfection and sterilization of surfaces during a later period may have adverse effects.

Psychosocial Factors, Condomless Sex, and Detectable Viral Load in HIV-Positive Women in Serodiscordant Couples in Nairobi, Kenya

This prospective study of HIV-positive Kenyan women in serodiscordant couples examined relationships between psychosocial factors, viral suppression, and condomless sex. Participants were screened for alcohol use disorders and intimate partner violence (IPV) annually and depressive symptoms every 6 months. Prostate specific antigen (PSA) detection was used as a marker for condomless sex. A total of 151 participants contributed 349 person-years of follow-up. Hazardous/harmful alcohol use was associated with increased risk of detecting PSA in vaginal secretions (aRR 1.99, 95%CI 1.08-3.66, χ2 = 4.85 (1)), while IPV and depression were not. Events representing HIV transmission potential, where there was biological evidence of condomless sex at a visit with a detectable plasma viral load, were observed at 2% of visits. The high prevalence of IPV and association between alcohol use and sexual risk suggest the need for monitoring and support for these conditions as part of comprehensive HIV care for women.

Spatial risk assessment of an emerging pandemic under data scarcity: A case of COVID-19 in Eswatini

Coronavirus (COVID-19) has rapidly spread across many countries in pandemic proportions since the first case was reported in Hubei, China in December 2019. Understanding transmission, susceptibility and exposure risks is crucial for surveillance, control and response to the disease. Knowing the geographic distribution of health resource scarcity areas is necessary if a country is to adequately anticipate and prepare for the full impact of infections. We explored the potential to undertake a spatial risk assessment of an emerging pandemic under data scarcity in Eswatini. We used a set of socio-economic and demographic variables to identify epidemic risk prone areas in the country. Three risk zone levels for COVID-19 were identified in the country. The analysis showed that about 29% (320 818) of the population were located in the high risk zone and these were people who could potentially be infected with COVID-19 in the absence of mitigation measures. A majority of cases and deaths attributed to COVID-19 would likely remain unknown but our estimate could be used to gauge the full burden of the disease. Approximating and quantifying the number of people who may be potentially infected with COVID-19 remains impossible under data scarcity and limited healthcare capacity especially in sub-Saharan Africa. We provided an estimation method that could support the pandemic risk forecasting, preparedness and response measures in the midst of data scarcity. The resultant map products could be used to guide on-the-ground surveillance and response efforts.

Data driven estimation of novel COVID-19 transmission risks through hybrid soft-computing techniques

Coronavirus genomic infection-2019 (COVID-19) has been announced as a serious health emergency arising international awareness due to its spread to 201 countries at present. In the month of April of the year 2020, it has certainly taken the pandemic outbreak of approximately 11,16,643 infections confirmed leading to around 59,170 deaths have been recorded world-over. This article studies multiple countries-based pandemic spread for the development of the COVID-19 originated in the China. This paper focuses on forecasting via real-time responses data to inherit an idea about the increase and maximum number of virus-infected cases for the various regions. In addition, it will help to understand the panic that surrounds this nCoV-19 for some intensely affecting states possessing different important demographic characteristics that would be affecting the disease characteristics. This study aims at developing soft-computing hybrid models for calculating the transmissibility of this genome viral. The analysis aids the study of the outbreak of this virus towards the other parts of the continent and the world. A hybrid of wavelet decomposed data into approximations and details then trained & tested through neuronal-fuzzification approach. Wavelet-based forecasting model predicts for shorter time span such as five to ten days advanced number of confirmed, death and recovered cases of China, India and USA. While data-based prediction through interpolation applied through moving average predicts for longer time spans such as 50-60 days ahead with lesser accuracy as compared to that of wavelet-based hybrids. Based on the simulations, the significance level (alpha) ranges from 0.10 to 0.67, MASE varying from 0.06 to 5.76, sMAPE ranges from 0.15 to 1.97, MAE varies from 22.59 to 6024.76, RMSE shows a variation from 3.18 to 8360.29 & R² varying through 0.0018 to 0.7149. MASE and sMAPE are relatively lesser applied and novel measures that aimed to achieve increase in accuracy. They eliminated skewness and made the model outlier-free. Estimates of the awaited outburst for regions in this study are India, China and the USA that will help in the improvement of apportionment of healthcare facilities as it can act as an early-warning system for government policy-makers. Thus, data-driven analysis will provide deep insights into the study of transmission of this viral genome estimation towards immensely affected countries. Also, the study with the help of transmission concern aims to eradicate the panic and stigma that has spread like wildfire and has become a significant part of this pandemic in these times.

[Assessment of schistosomiasis transmission risk in Nanjian County of Yunnan Province in 2019]

OBJECTIVE

To assess the schistosomiasis transmission risk in Nanjing County, so as to provide the scientific evidence for the development of the schistosomiasis control strategy and consolidation of the control achievements.

METHODS

On May 2019, the Deqiu Village in Deqiu Town and Baiyun Village in Nanjing Town of Yunnan Province, where schistosomiasis were historically relatively highly endemic, were selected to assess the risk of transmission of schistosomiasis by means of a retrospective review of the data pertaining to the historical endemic situation and schistosomiasis control, combined with a cross-sectional survey of snail and wild feces distribution.

RESULTS

During the period between 2017 and 2018, the mean sero-prevalence rates of Schistosoma japonicum infections were 6.76% (202/2 990) and 2.86% (142/4 971) in humans and 0 (0/1 160) and 10.65% (31/291) in bovines in Deqiu and Baiyun villages of Nanjian County, respectively; however, no egg-positives were identified; in addition, there were 21.06 hm² snail habitats found, but no S. japonicum infections were detected in snails. In 2019, there was 6.17 hm² snail habitats detected, with 2.17% (245/11 298) occurrence of frames with snails and a 0.06 snails/0.1 m² density of living snails; however, no positives for nucleic acid detection were seen in snails; among the 136 wild fecal samples captures from 23 settings, no S. japonicum infections were identified.

CONCLUSIONS

The risk of schistosomiasis transmission remains at a low level in Nanjian County; however, the factors affecting the transmission of schistosomiasis have not been completed eliminated. The integrated schistosomiasis control strategy with an emphasis on the control of the source of S. japonicum infections requires to be reinforced to consolidate the control achievements.

[Flood disasters and schistosomiasis control]

Currently, the endemic situation of schistosomiasis has dropped to the lowest level in China; however, there are still factors affecting the transmission of schistosomiasis. Flood disasters may pose a great impact on the transmission of schistosomiasis and even affect the progress of schistosomiasis control and the consolidation of schistosomiasis control achievements. In 2020, major flood disasters occur across China. This paper analyzes the current status of schistosomiasis and the impact of flood disasters on the transmission of schistosomiasis in China, and systematically describes the assessment of and response to schistosomiasis transmission risk before flood disasters, the prevention of Schistosoma japonicum infections during flood disasters and the assessment of the endemic situation of schistosomiasis and surveillance of schistosomiasis after flood disasters. It is considered that schistosomiasis control is an important part of conventional schistosomiasis control activities and an important part of anti-flood and schistosomiasis-preventive activities in flood disaster-affected areas. It is recommended that emergence response interventions are implemented in a scientific and well-organized manner to avoid or reduce the risk of schistosomiasis transmission caused by flood disasters. In addition, the research on early surveillance and forecast approaches for schistosomiasis should be emphasized and reinforced to provide the scientific and precise tools for achieving the goal of the 13th Five-year Plan for Schistosomiasis Control and elimination of schistosomiasis in China.

Modelling the dynamics of exchanged novel coronavirus (2019-nCov) between regions in terms of time and space

To date, many models have been proposed which estimate the transmission risk of COVID-19 in terms of time; however, its dependency on space dimensions has been ignored. In this research, by multiplying risk parameters in certain regions and bridging, we obtain a stable action, which means that the transmission risk worldwide could shrink to a constant. Thus, by increasing the risk parameters in one region, the risk parameters in other regions decrease. Then, by adding space dimensions to the parameters in transmission risk models, and using the wave equations of manifolds for the regions, we obtain the dynamics of the exchanged novel coronavirus (2019-nCov) between countries. We calculate the risk factors of COVID19 for different regions in this model, and observe that they are in good agreement with experimental data.

Larval ecology and infestation indices of two major arbovirus vectors, Aedes aegypti and Aedes albopictus (Diptera: Culicidae), in Brazzaville, the capital city of the Republic of the Congo

BACKGROUND

Invasive mosquito species, such as Aedes albopictus in Congo can affect the distribution of native species, changing the vector composition and pattern of disease transmission. Here, we comparatively establish the geographical distribution and larval habitat preference of Ae. aegypti and Ae. albopictus and the risk of arbovirus disease outbreaks using Stegomyia indices in the city of Brazzaville, the capital of the Republic of the Congo.

METHODS

Human dwelling surveys of water-holding containers for immature stages of Aedes was carried out in December 2017 in Brazzaville through a random cluster sampling method. A total of 268 human dwellings distributed in 9 boroughs and 27 neighbourhoods were surveyed across the city.

RESULTS

Overall, 455 potential larval habitats were surveyed. Both Ae. aegypti and Ae. albopictus were collected across the city with an overall high prevalence of Ae. aegypti (53.1%) compared to Ae. albopictus (46.9%). Geographical distribution analysis showed that Ae. aegypti was more abundant (mean = 6.6 ± 1.4) in neighbourhoods located in downtown, while the abundance of Ae. albopictus was low (mean = 3.5 ± 0.6) in suburbs. Peridomestic containers, especially discarded tanks, were the most strongly colonized productive larval habitat for both mosquito species with the prevalence of 56.4% and 53.1% for Ae. aegypti and Ae. albopictus, respectively. Globally, the house index (HI), Breteau index (BI) and container index (CI) were high for Ae. aegypti (26.6%, 38.4% and 22.6%) and Ae. albopictus (33.3%, 49.6% and 26.6%) compared to the transmission risk threshold (5%, 5% and 20%) established by the WHO/PAHO. Overall, pupae-based indices (the pupae index and the pupae per person index) were not significantly different between Ae. aegypti (273.4% and 23.2%) and Ae. albopictus (228.8% and 19.5%).

CONCLUSIONS

The findings of this study suggest a high risk for transmission of arbovirus diseases in Brazzaville and call for an urgent need to implement vector control strategies against these vectors in the Republic of the Congo.

Unique challenges in pediatric anesthesia created by COVID-19

Coronavirus disease 2019 (COVID-19) has affected anesthetic care worldwide, including the provision of anesthesia for pediatric patients. Hospitals have balanced the risks associated with the potential surges of resource-intensive COVID-19 patients against the probable morbidity of delaying elective surgical procedures. These decisions are complicated by the unclear influence that COVID-19 has on the perioperative risk for disease-positive pediatric patients. We conducted a comprehensive literature search on MEDLINE for publications involving pediatric patients with COVID-19 who underwent general anesthesia. A total of eight publications met inclusion criteria, and together described 20 patients. Nine patients had documented preoperative COVID-19 symptoms and one perioperative death was reported. Overall, further studies are needed to increase patient numbers and properly assess the perioperative risk. As we continue to provide care without clear guiding data, we present a discussion of modified anesthetic techniques for pediatric patients with suspected or confirmed COVID-19.

Entomological assessment of the risk of dengue outbreak in Abomey-Calavi Commune, Benin

Background

In May 2019, a confirmed dengue fever case was detected at the local hospital of Abomey-Calavi Commune in southern Benin. In Benin, there remains a dearth of literature concerning the distribution and biology of Aedes aegypti, the principal vector of dengue fever. This study was initiated by the Ministry of Health to partially fill this gap. The findings allowed us to assess the arboviral transmission risk incurred by the population of Abomey-Calavi to support programmatic decision-making.

Methods

Entomological assessments were conducted in 5% of the houses, meaning 314 houses selected from 11 boroughs in Abomey-Calavi Centre district and 9 villages in Hêvié district. The surveyed breeding sites were water containers located in (domestic) and around (peri-domestic) the dwellings. When a container was positive (housing larvae), a portion of the immature population was sampled with a larval dipper and poured into labeled jars. Immatures were then reared to adulthood at the Centre de Recheche Entomologique de Cotonou (CREC) insectary. Adult mosquitoes were morphologically identified to species level by site and, a subsample of the collected Ae. aegypti mosquitoes were used for WHO susceptibility tube tests.

Results

Of the 1372 adult Aedes specimens which emerged from the collected larvae and pupae, 1356 Ae. aegypti (98.83%), 10 Ae. luteocephalus, and 4 Ae. vittatus were identified. The Breteau indices were 160.2 in Abomey-Calavi Centre and 150 in Hêvié, whereas the House indices were 58.5% and 61.6% in the respective districts. WHO insecticide susceptibility tube tests showed that the mortality rates were 38.71% in Abomey-Calavi Centre and 85.71% in Hêvié for permethrin, and 72.22% in Abomey-Calavi Centre and 100% in Hêvié for deltamethrin.

Conclusion

The two districts were highly infested by Ae. aegypti whose breeding sites were mostly man-made. Considering this, human behavioral change to substantially reduce the number of larval habitats is necessary to control the vector populations. As Aedes mosquitoes are day biters, the use of repellents such as ointments and smoke coils can also be useful.

[Surveillance and control strategy of imported schistosomiasis mansoni: an expert consensus]

In 1980s, Biomphalaria straminea, an intermediate host of Schistosoma mansoni, was found in Shenzhen City, Guangdong Province, China, and currently, this snail has colonized in Shenzhen City and spread to peripheral cities involving of Dongguan and Huizhou. Since imported cases infected with S. mamoni have been reported from time to time in China, Mainland China is facing the potential risk of transmission of schistosomiasis mansoni. With the deepening of the opening-up policy, notably the implementation of the Belt and Road Initiative, there is an increase in the risk of transmission of schistosomiasis mansoni in Mainland China. Increasing the understanding on schistosomiasis mansoni, improving the awareness toward schistosomiasis mansoni prevention and control, and identifying, reporting and managing imported cases with S. mansoni infection or pathogen carriers, are of particular importance to prevent the development of entire life cycle of S. mansoni and the resultant schistosomiasis mansoni transmission in China. To protect public health, a consensus has been reached pertaining to the surveillance and control strategy of imported schistosomiasis mansoni by Chinese infectious disease experts and parasitologists, with aims to improve the awareness and capability for the diagnosis, treatment and control of imported schistosomiasis mansoni among Chinese disease control and prevention institutions and medical institutions, and decrease and even eliminate the risk of schistosomiasis mansoni transmission in China.

[Endemic situation of schistosomiasis in People's Republic of China from 2010 to 2017]

OBJECTIVE

To understand the epidemic trend of schistosomiasis in China from 2010 to 2017 so as to provide the scientific evidence for schistosomiasis elimination.

METHODS

The information of schistosomiasis control nationwide from 2010 to 2017 was collected, including the endemic of population, status of livestock control, and Oncomelania hupensis snail control. Microsoft Excel was applied for datum management and analysis.

RESULTS

From 2010 to 2017, the epidemic of schistosomiasis in China dropped significantly. The decreasing amplitude of estimated number of patients nationwide was 88.46%. Seventy-one acute schistosomiasis patients were reported and 12.68% (9/71) of them were imported. The decreasing rate of cultivated cattle was 50.09%, and the accumulative number of schistosome-infected cattle was 17 239, and the average positive rate of stool examinations decreased from 1.04% to 0.000 22%. The area with snails nationwide was 373 596.18 to 363 068.95 hm², and the new detected area with snails was 46.71 to 1 346.73 hm². The area with schistosome-infected snails was 171.68 hm² in 2012 and it was 9.25 hm² in 2013. In 72 key monitoring points of 7 endemic provinces, there were 17 schistosome positive points of water body in 2010 and 6 points in 2016. There were some high risk-factors related to schistosomiasis transmission including schisto-some-infected cattle, dogs, and field rats, and the field stools, and the pasture in the area with snails in schistosomiasis monitoring points.

CONCLUSIONS

The endemic status of schistosomiasis in China has dropped significantly, and the transmission level is very low. However, the infectious source and risk factors in the endemic environments have not be eliminated. Therefore, the infectious source control, health education, snail control, and transmission monitoring should be strengthened, so as to promote the progress of schistosomiasis elimination.

First report on the transmission of Zika virus by Aedes (Stegomyia) aegypti (L.) (Diptera: Culicidae) during the 2018 Zika outbreak in India

In a recent outbreak of Zika virus (ZIKV) infection in Jaipur city (Rajasthan, India), a total of 159 cases were reported in September 2018. In order to identify vector responsible for Zika transmission, mosquitoes were collected from houses with reported Zika cases and nearby houses. A total of 108 pools containing 522 mosquitoes were tested for presence of ZIKV using RT-PCR and Real Time RT-PCR. We detected presence of ZIKV in three pools of Aedes (Stegomyia) aegypti (L.), out of a total of 79 pools with 383 Ae. aegypti through RT-PCR as well as real-time RT-PCR. The presence of ZIKV in Ae. aegypti was further confirmed by DNA sequencing of the partial envelope region of ZIKV. Homology search of DNA sequence revealed highest identity (100%) with a ZIKV isolate from human from the study area which support the role of Ae. aegypti acting as a ZIKV vector. All other mosquitoes (Aedes vittatus and Culex quinquefasciatus) were negative for ZIKV. None of the F1 generation mosquito pools (276 mosquitoes in 43 pools) were found positive. This is the first report of presence of ZIKV in Ae. aegypti from the Indian subcontinent.

[Impact of earthquake disaster on schistosomiasis transmission and emergency prevention and control in Sichuan Province]

Earthquake is a serious natural disaster. The earthquake that occurs in schistosomiasis-endemic areas not only causes direct human and economic losses, but also induces secondary disasters that greatly threaten public health safety in affected areas. This paper analyzed the impact of the 2008 Wenchuan Earthquake and 2013 Lushan Earthquake on schistosomiasis transmission in Sichuan Province, and proposed emergency measures and assessment activitiesresponding to schistosomiasis following earthquake disasters. The experiences from schistosomiasis control after two earthquake disasters in Sichuan Province may provide insights into the emergency control in other regions or after other natural disasters.

[Construction and application of the surveillance system for schistosomiasis transmission risk in Sichuan Province]

OBJECTIVE

To build a schistosomiasis transmission risk surveillance system in Sichuan Province, so as to provide technical support for facilitating the progress towards schistosomiasis elimination in the province.

METHODS

The surveillance sites for schistosomiasis transmission risk were assigned in 63 endemic counties (districts) of 11 cities (prefectures) in Sichuan Province. During the period from 2015 through 2018, wild feces contamination, the sources of Schistosoma japonicum infections (fever patients, livestock and wild animals), water infectivity in key settings, snail distribution in key settings, and snail breeding risk (snail importation and spread, floating debris carrying snails and snail breeding in ecological wetlands) were monitored in the surveillance sites.

RESULTS

From 2015 to 2018, a total of 1 636 wild faces were detected in Sichuan Province, and 3 faces were positive for S. japonicum, with a 0.18% positive rate; among 3 995 livestock and 59 wild mice monitored, no S. japonicum infection was detected. A total of 49 414 fever patients were monitored in 2018, and 493 were seropositive for S. japonicum infection; then, 445 seropositives were subjected to stool examinations, and no egg-positives were found. From 2010 to 2018, a total of 93 sentinel sites were assigned, and 3 994 sentinel mice were placed for monitoring the water infectivity, with one S. japonicum-infected mouse detected. Between 2015 and 2018, a total of 4 156 key settings were investigated covering an area of 1 998.46 hm², and 668 settings were detected with snails (16.07%), covering an area of 193.26 hm²; 497 suspected settings with a likelihood of snail importation with plant introduction were monitored from 2017 to 2018, and 65 settings with snails were found with 2 673 snails captured; 593 sites were assigned to collect the floating debris from 2017 to 2018, and 9 191.39 kg floating debris were collected with 186 snails captured; 4 wetlands were monitored for the risk of schistosomiasis transmission from 2013 to 2015, and snail breeding was found in 2 wetlands. No S. japonicum infection was identified in snails captured from all surveillance sites.

CONCLUSIONS

A sensitive and effective schistosomiasis transmission risk surveillance system has been successfully established in Sichuan Province. There is still a risk of schistosomiasis transmission risk in local areas of Sichuan Province. Therefore, the integrated schistosomiasis control measures with emphasis on the control of the source of S. japonicum infections should be further intensified, and snail monitoring and control and monitoring and control of schistosomiasis in wetlands should be also intensified.

[Spatial - temporal clustering analysis of schistosomiasis transmission risk in Yunnan Province from 2004 to 2015]

OBJECTIVE

To explore the spatial-temporal clustering distribution of schistosomiasis transmission risk in Yunnan Province from 2004 to 2015, so as to provide scientific evidence for the future schistosomiasis control and consolidation of the control achievements.

METHODS

All data pertaining to endemic situation of human and bovine schistosomiasis and snail survey at a township level in Yunnan Province from 2004 to 2015 were collected. A descriptive epidemiological method and Joinpoint model were used to describe the changing trends of Schistosoma japonicum infections in humans, bovine and snails, and the hotspots and clusters of schistosomiasis transmission risk were identified using spatial autocorrelation analysis, hotspots analysis and retrospective space-time scan statistic in Yunnan Province from 2004 to 2015.

RESULTS

The prevalence of S. japonicum infections appeared a continuous decline in humans, bovine and snails in Yunnan Province from 2004 to 2015, and the estimated number of schistosomiasis cases reduced from 43 056 in 2004 to 756 in 2015, with a decline rate of 98.24%. There were no acute cases since 2008 and no infected snails since 2014 in Yunnan Province. There were significant differences in the changing trends of human and bovine S. japonicum infections in Yunnan Province between 2012 and 2015 and between 2013 and 2015, respectively using the Joinpoint model (P < 0.05). In addition, there was a spatial autocorrelation in human S. japonicum infections in Yunnan Province from 2004 to 2013 (P < 0.01), and the hotspots areas for human S. japonicum infections were mainly distributed in some townships from Dali City, Weishan County and Eryuan County. Retrospective spatial-temporal scanning revealed that S. japonicum human, bovine and snail infections were clustered in 23, 15, 4 townships from Dali City, Weishan County, Eryuan County, Nanjian County and Heqing County, respectively, with relative risks of 6.25 to 28.75 (P < 0.01), which was almost consistent with the cluster areas detected by hotspots analysis.

CONCLUSIONS

The endemic situation of schistosomiasis significantly reduced in Yunnan Province from 2004 to 2015; however, there is still a risk of schistosomiasis transmission. The monitoring and control of schistosomiasis should be intensified in the future in Yunnan Province.

The potential impact of initiating antiretroviral therapy with integrase inhibitors on HIV transmission risk in British Columbia, Canada

BACKGROUND

Available agents within the integrase strand-transfer inhibitor (INSTI) class have been shown to lead to a faster decay in viral load than other regimens. Therefore, we estimated the potential reduction in HIV transmission risk among antiretroviral-naïve individuals initiating on INSTI-based antiretroviral therapy (ART), focusing on the gay, bisexual and other men who have sex with men (gbMSM) population and various degrees of sexual activity.

METHODS

Using two mathematical models that estimate the HIV transmission risk corresponding to different viral loads, we estimated the average probability of HIV transmission per risky contact for gbMSM during the six months post-ART initiation, stratified by stage of HIV infection, viral load at ART initiation and type of first-line ART (i.e., INSTI or non-INSTI-based ART). This study focused individuals who initiated ART between 2011 and 2016 with at least one year of follow-up in British Columbia, Canada.

FINDINGS

Time to first virologic suppression for INSTI-based regimens was 21.4 days (95% credible interval (CI) 19.9-23.2), compared to 58.6 days (95% CI 54.1-62.2) for non-INSTI regimens. We showed that INSTI-based regimens could reduce the HIV transmission risk by at least 25% among those with viral load ≥ 5 log₁₀ copies/mL at ART initiation.

INTERPRETATION

Initiating ART on INSTI-based regimens has the potential to reduce HIV transmission risk among individuals with high baseline viral load levels, especially among those with high levels of sexual activity.

FUNDING

The British Columbia Ministry of Health, the Canadian Institutes of Health Research, and the Michael Smith Foundation for Health Research.

[Transmission risk matrix assessment of imported leishmaniasis in China]

OBJECTIVE

To assess the risk of imported leishmaniasis in China, offering scientific evidences for leishmaniasis prevention and control.

METHODS

The expert consultation method was used to establish a risk index system, and the risk matrix was used to evaluate the risk scales of leishmaniasis.

RESULTS

This risk assessment indicator system included 3 first-grade indexes and 13 second-grade indexes to the aspect of risk probability. Five indexes were also included on the aspect of the risk hazard severity in this system. The transmission risk matrix assessment showed that the risk of imported leishmaniasis transmission in China was in low risk level.

CONCLUSIONS

This risk matrix assessment is applied for the transmission of imported leishmaniasis in China in the first time, indicating the potential risk of imported leishmaniasis in China.

[Assessment of schistosomiasis transmission risk after flood damage in Wuhan City]

OBJECTIVE

To assess the schistosomiasis transmission risk after flood damage in Wuhan City.

METHODS

Schistosomiasis epidemic villages in Wuhan City were selected by using probability proportional to size sampling (PPS). The field investigations of Oncomelania hupensis snails, the activity of people and cattle on marshland, water infectivity of schistosome, reservoir host infection and wild feces contamination were conducted. I-III levels of risk environments were assessed and treated with appropriate measures.

RESULTS

A total of 90 schistosomiasis epidemic villages and 170 environments were monitored. Totally 9 811 snails were dissected but no Schistosoma japonicum infected snails were found. There were significant decreases in the density of snails and the survival rate of living snails after the flood (χ² = 102.517, t = 4.724, both P < 0.01). Totally 289 pieces of wild feces were captured, and no eggs of S. japonicum were detected. A total of 11 surveillance and forecast sites were detected on water systems, and 221 sentinel mice were placed. After breeding, 219 sentinel mice survived (99.10%), and no schistosome infection was detected. In addition, 1 720 mouse traps were placed in 3 survey sites, and 66 Apodemus agrarius were captured, and no schistosome-infected ones were found. All of the environments were assessed as Grade III. Meanwhile, 5 key schistosomiasis control areas were determined, and no emergency happened after the implementation of comprehensive control interventions.

CONCLUSIONS

The risk of schistosomiasis transmission remains low in Wuhan City after the flood, but the potential epidemic risk cannot be ignored.