2020年 · 第09卷第04期

Bacteria of the genusBrucellacause brucellosis, one of the world’s neglected zoonotic diseases. It is a disease of poverty; infections of livestock have a huge socioeconomic cost while human brucellosis starts as a debilitating acute infection that can be come chronic with many complications. The figure of 500 000 new human cases each year is regularly cited in reviews and research papers, however this is a vast under estimation; many of the most affected countries do not have the infrastructure for diagnosis and the broad spectrum of symptoms are shared with other febrile infections.

The outbreak of coronavirus disease 2019 (COVID-19) has caused a public catastrophe and global concern. The main symptoms of COVID-19 are fever, cough, myalgia, fatigue and lower respiratory tract infection signs. Almost all populations are susceptible to the virus, and the basic reproduction number (R₀) is 2.8-3.9. The fight against COVID-19 should have two aspects: one is the treatment of infected patients, and the other is the mobilization of the society to avoid the spread of the virus. The treatment of patients includes supportive treatment, antiviral treatment, and oxygen therapy. For patients with severe acute respiratory distress syndrome (ARDS), extracorporeal membrane oxygenation (ECMO) and circulatory support are recommended. Plasma therapy and traditional Chinese medicine have also achieved good outcomes. This review is intended to summarize the research on this new coronavirus, to analyze the similarities and differences between COVID-19 and previous outbreaks of severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS) and to provide guidance regarding new methods of prevention, diagnosis and clinical treatment based on autodock simulations.

This review compares the multifaceted characteristics of the three coronaviruses including COVID-19, SARS and MERS. Our researchers take the COVID-19, SARS, and MERS as key words and search literatures in the Pubmed database. We compare them horizontally and vertically which respectively means concluding the individual characteristics of each coronavirus and comparing the similarities and differences between the three coronaviruses.

We searched for studies on each outbreak and their solutions and found that the main biological differences among SARS-CoV-2, SARS-CoV and MERS-CoV are in ORF1a and the sequence of gene spike coding protein-S. We also found that the types and severity of clinical symptoms vary, which means that the diagnosis and nursing measures also require differentiation. In addition to the common route of transmission including airborne transmission, these three viruses have their own unique routes of transmission such as fecal-oral route of transmission COVID-19.

In evolutionary history, these three coronaviruses have some similar biological features as well as some different mutational characteristics. Their receptors and routes of transmission are not all the same, which makes them different in clinical features and treatments. We discovered through the autodock simulations that Met124 plays a key role in the efficiency of drugs targeting ACE2, such as remdesivir, chloroquine, ciclesonide and niclosamide, and may be a potential target in COVID-19.

From the begging months of 2020 a severe acute respiratory syndrome coronavirus (SARS-CoV-2, also called 2019-nCoV) caused a devastating global outbreak. At present, the diagnosis of coronavirus disease 2019 (COVID-19) is made through a nasopharyngeal swab based on reverse transcription polymerase chain reaction (RT-PCR) technique. However, some recent studies suggested the possible role of oral fluids and saliva in the detection of SARS-CoV-2. The purpose of this scoping review is evaluating the available evidence regarding the efficacy of saliva as a diagnostic specimen in COVID-19 patients.

A systematic literature review of six databases (PubMed, Scopus, The Cochrane Central Register of Controlled Trials [CENTRAL], Science Direct, Web of Science and Google scholar) was carried out without any restrictions on date of publication to identify the reliability of saliva as a diagnostic specimen for detection of SARS-CoV-2 in suspected patients.

Nine eligible articles were included in this review based on our described method. All the included studies are based on clinical surveys among patients with confirmed SARS-CoV-2 infection. Most of studies included in this review, reported that there is no statistically significant difference between nasopharyngeal or sputum specimens and saliva samples regarding viral load.

Despite limitations of this study, the findings of this review suggest that the use of self-collected saliva as a non-invasive specimen has proper accuracy and reliability regarding detection of SARS-CoV-2 based on RT-PCR technique.

Visceral leishmaniasis (VL) was one of the most important parasitic diseases in China, caused by Leishmania protozoans and transmitted by sand flies. Recently VL cases have reappeared in China, including the extension region of the Loess Plateau. The purpose of this study was to collect fundamental data on the host-vector VL system in the Loess Plateau to assist in the development of prevention and control measures.

Sand flies were collected by light traps from rural areas in Shanxian, Henan, China in 2015, as well as in Wuxiang and Yangquan, Shanxi, China in 2017. The blood sources of sand flies were analyzed by PCR detecting the host-specific mitochondrial cytochrome b (mtDNA cyt b) gene fragments. Leishmania infection in sand flies was detected by amplifying and sequencing ribosomal DNA internal transcribed spacer 1 (ITS1). The Leishmania specific antibodies in the sera of local dogs were detected by ELISA kit.

Blood sources showed diversity in the extension region of the Loess Plateau, including human, chicken, dog, cattle, pig and goat. Multiple blood sources within a sand fly were observed in samples from Yangquan (17/118, 14.4%) and Wuxiang (12/108, 11.1%). Leishmania DNA was detected in sand flies collected from Yangquan with minimum infection rate of 1.00%. The ITS1 sequences were conserved with the Leishmania donovani complex. The positive rate of Leishmania specific antibodies in dogs was 5.97%.

This study detected the blood sources and Leishmania parasites infection of sand flies by molecular methods in the extension region of Loess Plateau, China. A high epidemic risk of leishmaniasis is currently indicated by the results as the infection of Leishmania in sand flies, the extensive blood sources of sand flies including humans, and positive antibody of Leishmania in local dog sera. Given the recent increase of VL cases, asymptomatic patients, dogs and other potential infected animals should be screened and treated. Furthermore, the density of sand flies needs to be controlled and personal protection should be strengthened.

The coronavirus disease 2019 (COVID-19) outbreak has seriously endangered the health and lives of Chinese people. In this study, we predicted the COVID-19 epidemic trend and estimated the efficacy of several intervention strategies in the mainland of China.

According to the COVID-19 epidemic status, we constructed a compartmental model. Based on reported data from the National Health Commission of People’s Republic of China during January 10-February 17, 2020, we estimated the model parameters. We then predicted the epidemic trend and transmission risk of COVID-19. Using a sensitivity analysis method, we estimated the efficacy of several intervention strategies.

The cumulative number of confirmed cases in the mainland of China will be 86 763 (95% CI: 86 067-87 460) on May 2, 2020. Up until March 15, 2020, the case fatality rate increased to 6.42% (95% CI: 6.16-6.68%). On February 23, 2020, the existing confirmed cases reached its peak, with 60 890 cases (95% CI: 60 350-61 431). On January 23, 2020, the effective reproduction number was 2.620 (95% CI: 2.567-2.676) and had dropped below 1.0 since February 5, 2020. Due to governmental intervention, the total number of confirmed cases was reduced by 99.85% on May 2, 2020. Had the isolation been relaxed from February 24, 2020, there might have been a second peak of infection. However, relaxing the isolation after March 16, 2020 greatly reduced the number of existing confirmed cases and deaths. The total number of confirmed cases and deaths would increase by 8.72 and 9.44%, respectively, due to a 1-day delayed diagnosis in non-isolated infected patients. Moreover, if the coverage of close contact tracing was increased to 100%, the cumulative number of confirmed cases would be decreased by 88.26% on May 2, 2020.

The quarantine measures adopted by the Chinese government since January 23, 2020 were necessary and effective. Postponing the relaxation of isolation, early diagnosis, patient isolation, broad close-contact tracing, and strict monitoring of infected persons could effectively control the COVID-19 epidemic. April 1, 2020 would be a reasonable date to lift quarantine in Hubei and Wuhan.

The novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, also called 2019-nCoV) causes different morbidity risks to individuals in different age groups. This study attempts to quantify the age-specific transmissibility using a mathematical model.

An epidemiological model with five compartments (susceptible-exposed-symptomatic-asymptomatic-recovered/removed [SEIAR]) was developed based on observed transmission features. Coronavirus disease 2019 (COVID-19) cases were divided into four age groups: group 1, those ≤ 14 years old; group 2, those 15 to 44 years old; group 3, those 45 to 64 years old; and group 4, those ≥ 65 years old. The model was initially based on cases (including imported cases and secondary cases) collected in Hunan Province from January 5 to February 19, 2020. Another dataset, from Jilin Province, was used to test the model.

The age-specific SEIAR model fitted the data well in each age group (P < 0.001). In Hunan Province, the highest transmissibility was from age group 4 to 3 (median: β₄₃ = 7.71 × 10^-9; SAR₄₃ = 3.86 × 10^-8), followed by group 3 to 4 (median: β₃₄ = 3.07 × 10^-9; SAR₃₄ = 1.53 × 10^-8), group 2 to 2 (median: β₂₂ = 1.24 × 10^-9; SAR₂₂ = 6.21 × 10^-9), and group 3 to 1 (median: β₃₁ = 4.10 × 10^-10; SAR₃₁ = 2.08 × 10^-9). The lowest transmissibility was from age group 3 to 3 (median: β₃₃ = 1.64 × 10^-19; SAR₃₃ = 8.19 × 10^-19), followed by group 4 to 4 (median: β₄₄ = 3.66 × 10^-17; SAR₄₄= 1.83 × 10^-16), group 3 to 2 (median: β₃₂ = 1.21 × 10^-16; SAR₃₂ = 6.06 × 10^-16), and group 1 to 4 (median: β₁₄ = 7.20 × 10^-14; SAR₁₄ = 3.60 × 10^-13). In Jilin Province, the highest transmissibility occurred from age group 4 to 4 (median: β₄₃ = 4.27 × 10^-8; SAR₄₃ = 2.13 × 10^-7), followed by group 3 to 4 (median: β₃₄= 1.81 × 10^-8; SAR₃₄ = 9.03 × 10^-8).

SARS-CoV-2 exhibits high transmissibility between middle-aged (45 to 64 years old) and elderly (≥ 65 years old) people. Children (≤ 14 years old) have very low susceptibility to COVID-19. This study will improve our understanding of the transmission feature of SARS-CoV-2 in different age groups and suggest the most prevention measures should be applied to middle-aged and elderly people.

Coronavirus disease 2019 (COVID-19) was confirmed in Brazil in February 2020. Since then, the disease has spread throughout the country, reaching the poorest areas. This study analyzes the relationship between COVID-19 and the population’s living conditions. We aimed to identify social determinants related to the incidence, mortality, and case fatality rate of COVID-19 in Brazil, in 2020.

This is an ecological study evaluating the relationship between COVID-19 incidence, mortality, and case fatality rates and 49 social indicators of human development and social vulnerability. For the analysis, bivariate spatial correlation and multivariate and spatial regression models (spatial lag model and spatial error models) were used, considering a 95% confidence interval and a significance level of 5%.

A total of 44.8% of municipalities registered confirmed cases of COVID-19 and 14.7% had deaths. We observed that 56.2% of municipalities with confirmed cases had very low human development (COVID-19 incidence rate: 59.00/100 000; mortality rate: 36.75/1 000 000), and 52.8% had very high vulnerability (COVID-19 incidence rate: 41.68/100 000; mortality rate: 27.46/1 000 000). The regression model showed 17 indicators associated with transmission of COVID-19 in Brazil.

Although COVID-19 first arrived in the most developed and least vulnerable municipalities in Brazil, it has already reached locations that are farther from large urban centers, whose populations are exposed to a context of intense social vulnerability. Based on these findings, it is necessary to adopt measures that take local social aspects into account in order to contain the pandemic.

Since the first case of coronavirus disease 2019 (COVID-19) in Africa was detected on February 14, 2020, the cumulative confirmations reached 15 207 including 831 deaths by April 13, 2020. Africa has been described as one of the most vulnerable region with the COVID-19 infection during the initial phase of the outbreak, due to the fact that Africa is a great commercial partner of China and some other EU and American countries. Which result in large volume of travels by traders to the region more frequently and causing African countries face even bigger health threat during the COVID-19 pandemic. Furthermore, the fact that the control and management of COVID-19 pandemic rely heavily on a country’s health care system, and on average Africa has poor health care system which make it more vulnerable indicating a need for timely intervention to curtail the spread. In this paper, we estimate the exponential growth rate and basic reproduction number (R₀) of COVID-19 in Africa to show the potential of the virus to spread, and reveal the importance of sustaining stringent health measures to control the disease in Africa.

We analyzed the initial phase of the epidemic of COVID-19 in Africa between 1 March and 13 April 2020, by using the simple exponential growth model. We examined the publicly available materials published by the WHO situation report to show the potential of COVID-19 to spread without sustaining strict health measures. The Poisson likelihood framework is adopted for data fitting and parameter estimation. We modelled the distribution of COVID-19 generation interval (GI) as Gamma distributions with a mean of 4.7 days and standard deviation of 2.9 days estimated from previous work, and compute the basic reproduction number.

We estimated the exponential growth rate as 0.22 per day (95% CI: 0.20-0.24), and the basic reproduction number, R₀, as 2.37 (95% CI: 2.22-2.51) based on the assumption that the exponential growth starting from 1 March 2020. With an R₀ at 2.37, we quantified the instantaneous transmissibility of the outbreak by the time-varying effective reproductive number to show the potential of COVID-19 to spread across African region.

The initial growth of COVID-19 cases in Africa was rapid and showed large variations across countries. Our estimates should be useful in preparedness planning against further spread of the COVID-19 epidemic in Africa.

The point-of-care circulating cathodic antigen (POC-CCA) test is increasingly used as a rapid diagnostic method for Schistosoma mansoni infection. The test has good sensitivity, although false positive results have been reported among pregnant women and patients with urine infections and hematuria. We validated the POC-CCA test’s ability to diagnose Schistosoma mekongi infection in Lao People’s Democratic Republic (Lao PDR), where S. mekongi is endemic. Of particular interest was the test’s specificity and possible cross-reactivity with other helminth infections.

We conducted a cross-sectional study of children and adults in the provinces of Champasack (Schistosoma mekongi and Opisthorchis viverrini endemic), Savannakhet (O. viverrini endemic) and Luang Prabang (soil-transmitted helminths endemic) between October 2018 and April 2019. POC-CCA and urine dipstick tests were administered to all study participants, while an additional pregnancy test was offered to women. Two stool samples were collected from participants and examined with a Kato-Katz test (two smears per stool). Logistic regression was used to associate potential confounding factors (predictors) with POC-CCA test results (outcome).

In S. mekongi-endemic Champasack, 11.5% (n = 366) and 0.5% (n = 2) of study participants had positive POC-CCA and Kato-Katz test results, respectively. Only one of the two Kato-Katz positive patients was also POC-CCA positive. In Champasack and Luang Prabang, where S. mekongi is not endemic, the POC-CCA test yielded (presumably) false positive results for 6.0% (n = 22) and 2.5% (n = 9) of study participants, respectively, while all of the Kato-Katz tests were negative. POC-CCA positive test results were significantly associated with O. viverrini infection (1.69, 95% confidence interval (CI): 1.02-2.77, P = 0.042), increased leukocytes (adjusted Odds Ratio (aOR)= 1.58, 95% CI: 1.15-2.17, P= 0.005) and hematuria (aOR = 1.50, 95% CI: 1.07-2.10, P= 0.019) if the observed trace was counted as a positive test result. Two pregnant women from Champasack province had POC-CCA positive tests.

We observed a cross-reaction between the POC-CCA test and O. viverrini infection. To some extent, we can confirm previous observations asserting that POC-CCA provides false positive results among patients with urinary tract infections and hematuria. In S. mekongi-endemic areas, POC-CCA can be applied cautiously for surveillance purposes, keeping in mind the considerable risk of false positive results and its unknown sensitivity.

China incurs an extremely low treatment coverage of multidrug-resistant tuberculosis (MDR-TB). This study aimed to understand the experience of MDR-TB patients on quality of health care, and the clinical impact through an up to six-year follow-up.

Cohorts of MDR-TB patients were built in TB/MDR-TB designated hospitals in four regions of China from 2014 to 2015. Patients were followed up during treatment course, and yearly confirmation afterward until 2019. Delay in MDR-TB diagnosis and treatment was calculated upon bacteriological confirmation and treatment initiation. Risk factors for unfavourable outcomes were identified by multivariate logistic regression.

Among 1168 bacteriological-positive TB patients identified from a 12-million population, 58 (5.0%) MDR-TB cases were detected. The median delay for MDR-TB diagnosis was 90.0 days, with 13.8% having a delay above 180.0 days. MDR-TB treatment was only recommended to 19 (32.8%) participants, while the rest continued with regimen for drug-susceptible TB. In MDR-TB treatment group, 36.8% achieved treatment success, while the others had incomplete treatment (21.1%), loss to follow-up (36.8%) and TB relapse (5.3%). For non-MDR-TB treatment group, 33.3% succeeded, 25.6% relapsed, 2.6% failed, 23.1% died, and 15.4% were lost to follow-up. Overall, only 35.7% (20/56) of detected MDR-TB patients had favourable outcomes and higher education level was positively associated with it (adjusted odds ratio [aOR]: 3.60, 95% confidence interval [CI]: 1.04-12.5).

A large proportion of patients did not receive MDR-TB treatment and had unfavourable outcomes. Delayed MDR-TB diagnosis resulted in poor quality of MDR-TB care. Rapid diagnosis, regulated patient management and high-quality MDR-TB treatment should be enhanced in China.

Disease surveillance systems are essential for effective disease intervention and control by monitoring disease prevalence as time series. To evaluate the severity of an epidemic, statistical methods are widely used to forecast the trend, seasonality, and the possible number of infections of a disease. However, most statistical methods are limited in revealing the underlying dynamics of disease transmission, which may be affected by various impact factors, such as environmental, meteorological, and physiological factors. In this study, we focus on investigating malaria transmission dynamics based on time series data.

A data-driven nonlinear stochastic model is proposed to infer and predict the dynamics of malaria transmission based on the time series of prevalence data. Specifically, the dynamics of malaria transmission is modeled based on the notion of vectorial capacity (VCAP) and entomological inoculation rate (EIR). A particle Markov chain Monte Carlo (PMCMC) method is employed to estimate the model parameters. Accordingly, a one-step-ahead prediction method is proposed to project the number of future malaria infections. Finally, two case studies are carried out on the inference and prediction of Plasmodium vivax transmission in Tengchong and Longling, Yunnan province, China.

The results show that the trained data-driven stochastic model can well fit the historical time series of P. vivax prevalence data in both counties from 2007 to 2010. Moreover, with well-trained model parameters, the proposed one-step-ahead prediction method can achieve better performances than that of the seasonal autoregressive integrated moving average model with respect to predicting the number of future malaria infections.

By involving dynamically changing impact factors, the proposed data-driven model together with the PMCMC method can successfully (i) depict the dynamics of malaria transmission, and (ii) achieve accurate one-step-ahead prediction about malaria infections. Such a data-driven method has the potential to investigate malaria transmission dynamics in other malaria-endemic countries/regions.

As no globally accepted dengue vaccines or specific antiviral therapies are currently available, controlling breeding sites of Aedes aegypti is a target to prevent dengue outbreaks. The present study aimed to characterize outdoor artificial breeding sites in urban households using an exhaustive classification system.

A cross-sectional entomological survey was carried out in Colón city, Entre Ríos, Argentina, using a two-stage stratified sampling design during March and April 2014. The city was stratified given the degree of urbanization of each block, and blocks and households were randomly selected. All outdoor containers with water were inspected, and the presence of immature mosquitoes was recorded. Containers were classified according to physical, functional, and location attributes. Generalized linear mixed models were applied to take into account the aggregated nature of the data (containers in houses and houses in blocks).

Overall, 207 houses were inspected. Out of 522 containers with water, 25% had immatures of Ae. aegypti (7336). In adjusted models, the abundance of immatures was higher in containers with increasing opening surface and volume, without roof cover, exposed to shadow, out of use or with functions related to gardening activities, household chores, water storage, or construction. At block level, immatures abundance was positively associated with the degree of urbanization.

We detected high immatures abundance in containers associated with water utilization. This suggests that containers involved in these activities, whether directly (e.g., water storage) or indirectly (e.g., incomplete water drainage in the last use), are susceptible to present a high immature abundance. Although our results indicate the importance of the type of use over the type of container, we encourage the use of both classification criteria for artificial breeding sites of mosquitoes, mainly because these are complementary. Additionally, generalized linear mixed models allowed us to analyse predictor variables at different scales (container/house/block) and consider the lack of independence between observations. An exhaustive analysis of artificial breeding sites that use this analytical methodology can lead to new information that could help designing more appropriate tools for dengue surveillance and control.

Lassa fever is a zoonotic viral infection endemic to the West Africa countries. It is highly fatal during pregnancy and as such reports of neonatal onset Lassa fever infections are rare in scientific literature. We report a fatal case of Lassa fever in a 26-day-old neonate mimicking the diagnosis of late-onset neonatal sepsis.

The patient is a 26-day-old neonate who was admitted with a day history of fever, poor feeding, pre-auricular lymphadenopathy and sudden parental death. He was initially evaluated for late onset neonatal sepsis. He later developed abnormal bleeding and multiple convulsions while on admission, prompting the need to evaluate for Lassa fever using reverse transcription polymerase chain reaction (RT-PCR). He died 31 h into admission and RT-PCR result was positive for Lassa fever.

Neonatal Lassa fever infection is highly fatal and can mimic neonatal sepsis. High index of suspicion is needed particularly for atypical presentations of neonatal sepsis in Lassa fever endemic areas.

The emerging infectious disease, coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), poses a serious threat in China and worldwide. Challenged by this serious situation, China has taken many measures to contain its transmission. This study aims to systematically review and record these special and effective practices, in hope of benefiting for fighting against the ongoing worldwide pandemic.

The measures taken by the governments was tracked and sorted on a daily basis from the websites of governmental authorities (e.g. National Health Commission of the People’s Republic of China). And the measures were reviewed and summarized by categorizations, figures and tables, showing an ever-changing process of combating with an emerging infectious disease. The population shift levels, daily local new diagnosed cases, daily mortality and daily local new cured cases were used for measuring the effect of the measures.

The practices could be categorized into active case surveillance, rapid case diagnosis and management, strict follow-up and quarantine of persons with close contacts, and issuance of guidance to help the public understand and adhere to control measures, plus prompt and effective high-level policy decision, complete activation of the public health system, and full involvement of the society. Along with the measures, the population shift levels, daily local new diagnosed cases, and mortality were decreased, and the daily local new cured cases were increased in China.

China’s practices are effective in controlling transmission of SARS-CoV-2. Considering newly occurred situations (e.g. imported cases, work resumption), the control measures may be adjusted.

There is currently considerable international debate around school closures/openings and the role of children in the transmission of coronavirus disease 2019 (COVID-19). Whilst evidence suggests that children are not impacted by COVID-19 as severely as adults, little is still known about their transmission potential, and with a lot of asymptomatic cases they may be silent transmitters (i.e. infectious without showing clinical signs of disease), albeit at a lower level than adults. In relation to this, it is somewhat concerning that in many countries children are cared for, or are often in close contact with, older individuals such as grandparents - the age group most at risk of acquiring serious respiratory complications resulting in death.

We emphasise that in the absence of a vaccine or an effective therapeutic drug, preventive measures such as good hygiene practices - hand washing, cough etiquette, disinfection of surfaces and social distancing represent the major (in fact only) weapons that we have against COVID-19. Accordingly, we stress that there is a pressing need to develop specific COVID-19 prevention messages for schoolchildren.

An entertainment education intervention for schoolchildren systematically implemented in schools would be highly effective and fill this need. With such measures in place there would be greater confidence around the opening of schools.