scholarly journals Zika Virus: Endemic Versus Epidemic Dynamics and Implications for Disease Spread in the Americas

2016 ◽  
Author(s):  
Sharon Bewick ◽  
William F. Fagan ◽  
Justin Calabrese ◽  
Folashade Agusto

AbstractSince being introduced into Brazil in 2014, Zika virus (ZIKV) has spread explosively across Central and South America. Although the symptoms of ZIKV are generally mild, recent evidence suggests a relationship between prenatal exposure to ZIKV and microcephaly. This has led to widespread panic, including travel alerts and warnings to avoid pregnancy. Because ZIKV is an emerging disease, response efforts are complicated by limited understanding of disease dynamics. To this end, we develop a novel state- and class-structured compartment model for ZIKV. Our model shows that the risk of prenatal ZIKV exposure should decrease dramatically following the initial wave of disease, reaching almost undetectable levels in endemic systems. Our model also suggests that, depending on ZIVK transmission levels in the Americas, efforts to reduce ZIKV prenatal exposures through mosquito management and avoidance may have minimal benefit, and may even result in increased risk of microcephaly in later years of an outbreak.

2020 ◽  
Author(s):  
Andrew Fang ◽  
Jonathan Kia-Sheng Phua ◽  
Terrence Chiew ◽  
Daniel De-Liang Loh ◽  
Lincoln Ming Han Liow ◽  
...  

BACKGROUND During the Coronavirus Disease 2019 (COVID-19) outbreak, community care facilities (CCF) were set up as temporary out-of-hospital isolation facilities to contain the surge of cases in Singapore. Confined living spaces within CCFs posed an increased risk of communicable disease spread among residents. OBJECTIVE This inspired our healthcare team managing a CCF operation to design a low-cost communicable disease outbreak surveillance system (CDOSS). METHODS Our CDOSS was designed with the following considerations: (1) comprehensiveness, (2) efficiency through passive reconnoitering from electronic medical record (EMR) data, (3) ability to provide spatiotemporal insights, (4) low-cost and (5) ease of use. We used Python to develop a lightweight application – Python-based Communicable Disease Outbreak Surveillance System (PyDOSS) – that was able perform syndromic surveillance and fever monitoring. With minimal user actions, its data pipeline would generate daily control charts and geospatial heat maps of cases from raw EMR data and logged vital signs. PyDOSS was successfully implemented as part of our CCF workflow. We also simulated a gastroenteritis (GE) outbreak to test the effectiveness of the system. RESULTS PyDOSS was used throughout the entire duration of operation; the output was reviewed daily by senior management. No disease outbreaks were identified during our medical operation. In the simulated GE outbreak, PyDOSS was able to effectively detect an outbreak within 24 hours and provided information about cluster progression which could aid in contact tracing. The code for a stock version of PyDOSS has been made publicly available. CONCLUSIONS PyDOSS is an effective surveillance system which was successfully implemented in a real-life medical operation. With the system developed using open-source technology and the code made freely available, it significantly reduces the cost of developing and operating CDOSS and may be useful for similar temporary medical operations, or in resource-limited settings.


2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Pooja Sengupta ◽  
Bhaswati Ganguli ◽  
Sugata SenRoy ◽  
Aditya Chatterjee

Abstract Background In this study we cluster the districts of India in terms of the spread of COVID-19 and related variables such as population density and the number of specialty hospitals. Simulation using a compartment model is used to provide insight into differences in response to public health interventions. Two case studies of interest from Nizamuddin and Dharavi provide contrasting pictures of the success in curbing spread. Methods A cluster analysis of the worst affected districts in India provides insight about the similarities between them. The effects of public health interventions in flattening the curve in their respective states is studied using the individual contact SEIQHRF model, a stochastic individual compartment model which simulates disease prevalence in the susceptible, infected, recovered and fatal compartments. Results The clustering of hotspot districts provide homogeneous groups that can be discriminated in terms of number of cases and related covariates. The cluster analysis reveal that the distribution of number of COVID-19 hospitals in the districts does not correlate with the distribution of confirmed COVID-19 cases. From the SEIQHRF model for Nizamuddin we observe in the second phase the number of infected individuals had seen a multitudinous increase in the states where Nizamuddin attendees returned, increasing the risk of the disease spread. However, the simulations reveal that implementing administrative interventions, flatten the curve. In Dharavi, through tracing, tracking, testing and treating, massive breakout of COVID-19 was brought under control. Conclusions The cluster analysis performed on the districts reveal homogeneous groups of districts that can be ranked based on the burden placed on the healthcare system in terms of number of confirmed cases, population density and number of hospitals dedicated to COVID-19 treatment. The study rounds up with two important case studies on Nizamuddin basti and Dharavi to illustrate the growth curve of COVID-19 in two very densely populated regions in India. In the case of Nizamuddin, the study showed that there was a manifold increase in the risk of infection. In contrast it is seen that there was a rapid decline in the number of cases in Dharavi within a span of about one month.


Viruses ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1427
Author(s):  
Paula Sobral da Silva ◽  
Sophie Eickmann ◽  
Ricardo Ximenes ◽  
Celina Martelli ◽  
Elizabeth Brickley ◽  
...  

The relation of Zika virus (ZIKV) with microcephaly is well established. However, knowledge is lacking on later developmental outcomes in children with evidence of maternal ZIKV infection during pregnancy born without microcephaly. The objective of this analysis is to investigate the impact of prenatal exposure to ZIKV on neuropsychomotor development in children without microcephaly. We evaluated 274 children including 235 ZIKV exposed and 39 controls using the Bayley-III Scales of Infant and Toddler Development (BSIDIII) and neurological examination. We observed a difference in cognition with a borderline p-value (p = 0.052): 9.4% of exposed children and none of the unexposed control group had mild to moderate delays. The prevalence of delays in the language and motor domains did not differ significantly between ZIKV-exposed and unexposed children (language: 12.3% versus 12.8%; motor: 4.7% versus 2.6%). Notably, neurological examination results were predictive of neurodevelopmental delays in the BSIDIII assessments for exposed children: 46.7% of children with abnormalities on clinical neurological examination presented with delay in contrast to 17.8% among exposed children without apparent neurological abnormalities (p = 0.001). Overall, our findings suggest that relative to their unexposed peers, ZIKV-exposed children without microcephaly are not at considerably increased risk of neurodevelopmental impairment in the first 42 months of life, although a small group of children demonstrated higher frequencies of cognitive delay. It is important to highlight that in the group of exposed children, an abnormal neuroclinical examination may be a predictor of developmental delay. The article contributes to practical guidance and advances our knowledge about congenital Zika.


Author(s):  
Juan P Aguilar Ticona ◽  
Huma Baig ◽  
Nivison Nery Jr. ◽  
Simon Doss-Gollin ◽  
Gielson A Sacramento ◽  
...  

Abstract In order to understand the disease burden of sexually transmitted Zika virus (ZIKV), we prospectively followed a cohort of 359 adult and adolescent residents of an urban community in Salvador, Brazil through the 2015 ZIKV epidemic. Later, in 2017, we used a retrospective survey to associate sexual behavior during the epidemic with ZIKV infection as defined by IgG3-NS1 ELISA. We found that males who engaged in casual sexual encounters during the epidemic were more likely (ORa=6.2; 95%CI 1.2–64.1) to be ZIKV positive, suggesting that specific groups may be at increased risk of sexually transmitted infections.


2014 ◽  
Vol 24 (1) ◽  
pp. 48-53 ◽  
Author(s):  
Alejandra Martínez ◽  
Cristophe Pomel ◽  
Thomas Filleron ◽  
Marjolein De Cuypere ◽  
Eliane Mery ◽  
...  

ObjectiveThe aim of the study was to report on the oncologic outcome of the disease spread to celiac lymph nodes (CLNs) in advanced-stage ovarian cancer patients.MethodsAll patients who had CLN resection as part of their cytoreductive surgery for epithelial ovarian, fallopian, or primary peritoneal cancer were identified. Patient demographic data with particular emphasis on operative records to detail the extent and distribution of the disease spread, lymphadenectomy procedures, pathologic data, and follow-up data were included.ResultsThe median follow-up was 26.3 months. The median overall survival values in the group with positive CLNs and in the group with negative CLNs were 26.9 months and 40.04 months, respectively. The median progression-free survival values in the group with metastatic CLNs and in the group with negative CLNs were 8.8 months and 20.24 months, respectively (P = 0.053). Positive CLNs were associated with progression during or within 6 months after the completion of chemotherapy (P = 0.0044). Tumor burden and extensive disease distribution were significantly associated with poor progression-free survival, short-term progression, and overall survival. In multivariate analysis, only the CLN status was independently associated with short-term progression.ConclusionsDisease in the CLN is a marker of disease severity, which is associated to a high-risk group of patients with presumed adverse tumor biology, increased risk of lymph node progression, and worst oncologic outcome.


2018 ◽  
Vol 38 (11) ◽  
pp. 2023-2028
Author(s):  
Rísia L. Negreiros ◽  
José H.H. Grisi-Filho ◽  
Ricardo A. Dias ◽  
Fernando Ferreira ◽  
Valéria S.F. Homem ◽  
...  

ABSTRACT: The analysis of animal movement patterns may help identify farm premises with a potentially high risk of infectious disease introduction. Farm herd sizes and bovine movement data from 2007 in the state of Mato Grosso, Brazil, were analyzed. There are three different biomes in Mato Grosso: the Amazon, Cerrado, and Pantanal. The analysis of the animal trade between and within biomes would enable characterization of the connections between the biomes and the intensity of the internal trade within each biome. We conducted the following analyses: 1) the concentration of cattle on farm premises in the state and in each biome, 2) the number and relative frequency of cattle moved between biomes, and 3) the most frequent purposes for cattle movements. Twenty percent (20%) of the farm premises had 81.15% of the herd population. Those premises may be important not only for the spread of infectious diseases, but also for the implementation of surveillance and control strategies. Most of the cattle movement was intrastate (97.1%), and internal movements within each biome were predominant (88.6%). A high percentage of movement from the Pantanal was to the Cerrado (48.6%), the biome that received the most cattle for slaughter, fattening and reproduction (62.4%, 56.8%, and 49.1% of all movements for slaughter, fattening, and reproduction, respectively). The primary purposes for cattle trade were fattening (43.5%), slaughter (31.5%), and reproduction (22.7%). Presumably, movements for slaughter has a low risk of disease spread. In contrast, movements for fattening and reproduction purposes (66.2% of all movements) may contribute to an increased risk of the spread of infectious diseases.


2021 ◽  
Author(s):  
Satarupa Bhattacharjee ◽  
Shuting Liao ◽  
Debashis Paul ◽  
Sanjay Chaudhuri

AbstractWe describe a time dependent stochastic dynamic model in discrete time for the evolution of the COVID-19 pandemic in various states of USA. The proposed multi-compartment model is expressed through a system of difference equations that describe their temporal dynamics. Various compartments in our model is connected to the social distancing measures and diagnostic testing rates. A nonparametric estimation strategy is employed for obtaining estimates of interpretable temporally static and dynamic epidemiological rate parameters. The confidence bands of the parameters are obtained using a residual bootstrap procedure. A key feature of the methodology is its ability to estimate latent compartments such as the trajectory of the number of asymptomatic but infected individuals which are the key vectors of COVID-19 spread. The nature of the disease dynamics is further quantified by the proposed epidemiological markers, which use estimates of such key latent compartments.


2021 ◽  
Author(s):  
Wei Luo ◽  
Zhaoyin Liu ◽  
Yuxuan Zhou ◽  
Yumin Zhao ◽  
Yunyue Elita Li ◽  
...  

The global pandemic of COVID-19 presented an unprecedented challenge to all countries in the world, among which Southeast Asia (SEA) countries managed to maintain and mitigate the first wave of COVID-19 in 2020. However, these countries were caught in the crisis after the Delta variant was introduced to SEA, though many countries had immediately implemented non-pharmaceutical intervention (NPI) measures along with vaccination in order to contain the disease spread. To investigate the potential linkages between epidemic dynamics and public health interventions, we adopted a prospective space-time scan method to conduct spatiotemporal analysis at the district level in the seven selected countries in SEA from June 2021 to October 2021. Results reveal the spatial and temporal propagation and progression of COVID-19 risks relative to public health measures implemented by different countries. Our research benefits continuous improvements of public health strategies in preventing and containing this pandemic.


1992 ◽  
Vol 3 (2) ◽  
pp. 117-122 ◽  
Author(s):  
Kristina Ramstedt ◽  
Lars Forssman ◽  
Johan Giesecke ◽  
Fredrik Granath

Screening programmes are important for the control of Chlamydia trachomatis (Ct) infection, a disease spread mainly by asymptomatic carriers. Risk factors for Ct infection were assessed in 6810 consecutive asymptomatic young women seeking contraceptive advice. All women filled in a questionnaire and were offered Ct testing. Of the 5785 who consented to testing, 425 (7.3%) were Ct culture positive. Four variables were significantly related to increased risk of being infected: age 18–23 years, duration of present relationship < 1 year, non-use of condoms, and a history of not having had a previous genital infection. It is not possible to devise screening criteria that would effectively identify women at high risk. Therefore a screening programme should be targeted at all sexually active young people. However, if after some years the programme succeeds in lowering general Ct prevalence, these factors may be important when selecting patients for Ct testing.


2016 ◽  
Vol 11 (2) ◽  
pp. 163-167 ◽  
Author(s):  
Kelly G. Vest

AbstractZika virus has captivated the world with its quick spread throughout the Western Hemisphere. Increased emphasis has been placed on the infection of pregnant women and subsequent adverse and severe effects in the developing fetus and newborn. This article supplements a previous article and provides updated information on new and evolving evidence that strengthens the association between Zika virus and unique congenital and neurologic diseases, updates what is known about the epidemiology of the disease, and provides new and updated material for primary care providers as they counsel patients who may be exposed or infected. With the extent of disease spread, it is expected that Zika virus will become endemic to the Western Hemisphere and will change the public health parameters and approach in this area of the world. (Disaster Med Public Health Preparedness. 2017;11:163–167)


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