Modelling the effects of contaminated environments in mainland China on seasonal HFMD infections and the potential benefit of a pulse vaccination strategy

Substantial and increasing outbreaks of EV71-related hand, foot and mouth disease (HFMD) have occurred recently in mainland China with serious consequences for child health. The HFMD pathogens can survive for long periods outside the host in suitable conditions, and hence indirect transmission via free-living pathogens in the environment cannot be ignored. We propose a novel mathematical model of both periodic direct transmission and indirect transmission followed by incorporation of an impulsive vaccination strategy. By applying Floquet theory and the comparison theorem of impulsive differential equations, we obtained a threshold parameter which governs the extinction or the uniform persistence of the disease. The rate, frequency and timing of pulse vaccination were found to affect the basic reproduction number and the number of infected individuals significantly. In particular, frequent vaccination with a high coverage rate leads to declines in the basic reproduction number. Moreover, for a given rate of vaccination or frequency, numerical studies suggested that there was an optimal time (September, just before the start of new school terms) when the basic reproduction number and hence new HFMD infections could be minimised. Frequent high intensity vaccinations at a suitable time (e.g. September) and regular cleaning of the environment are effective measures for controlling HFMD infections

Modelling the effects of contaminated environments on HFMD infections in mainland China

Hand-foot-mouth disease (HFMD) has spread widely in mainland China increasing in prevalence in most years with serious consequences for child health. The HFMD virus can survive for a long period outside the host in suitable conditions, and hence contaminated environments may play important roles in HFMD infection. A new mathematical model was proposed and used to investigate the roles that asymptomatic individuals and contaminated environments played in HFMD dynamics. The model includes both direct transmission between susceptible and infected individuals and indirect transmission via free-living infectious unites in the environment. Theoretical analysis shows that the disease goes to extinction if the basic reproduction number is less than unity, whilst otherwise the disease persists. By fitting the proposed model to surveillance data we estimated the basic reproduction number as 1.509. Numerical simulations show that increasing the rate of virus clearance and decreasing transmission rates can delay epidemic outbreaks and weaken the severity of HFMD. Sensitivity analysis indicated that the basic reproduction number is sensitive to the transmission rate induced by asymptomatic infectious individuals and parameters associated with contaminated environments such as the indirect transmission rate, the rate of clearance and the virus shedding rates. This implies that asymptomatic infectious individuals and contaminated environments contribute substantially to new HFMD infections, and so would be targets for effective control measures

A Hand-Foot-and-Mouth Disease Model with Periodic Transmission Rate in Wenzhou, China

We establish an SEIQRS epidemic model with periodic transmission rate to investigate the spread of seasonal HFMD in Wenzhou. The value of this study lies in two aspects. Mathematically, we show that the global dynamics of the HFMD model can be governed by its reproduction number R0; if R01, the model has at least one positive periodic solution and is uniformly persistent, which indicates that HFMD becomes an endemic disease. Epidemiologically, based on the statistical data of HFMD in Wenzhou, we find that the HFMD becomes an endemic disease and will break out in Wenzhou. One of the most interesting findings is that, for controlling the HFMD spread, we must increase the quarantined rate or decrease the treatment cycle

Modelling and controlling infectious diseases

The financial support by IDRC has made it much easier to put together network activities involving scientists in both countries, a special example is the large presence of the Chinese students in the 2012 Summer School on Mathematics for Public Health the Canadian group organized in Edmonton in May of 2012.Infectious disease control is a major challenge in China due to China’s fast growing economy, changing social networks and evolving health service infrastructures. The success of disease control in China has a profound impact beyond its borders. In support of better disease control, this five year research program was designed to enhance China’s national capacity for analyzing, modeling and predicting transmission dynamics of infectious diseases through joint research, training young scientists, and building collaborative relationships. This successful program was led by the National Center for AIDS/STD Control and Prevention (Chinese Centre for Disease Control and Prevention, China) and the Centre for Disease Modeling (York University, Canada), and involved a number of Canadian and Chinese universities in various areas of infectious disease modelling and control. The bilateral collaboration also trained numerous highly qualified personnel and built a network for sustaining collaboration. This capacity building was facilitated by joint projects and bilateral annual meetings in major cities in China and Canada. The research activities on modeling major public health threats of infectious diseases focused on major diseases in China and/or issues of global public health concern including HIV transmission and prevention among high risk population, HIV treatment and drug resistance, influenza, schistosomiasis, mutation and stemma of SIV and HIV, latent and active tuberculosis infection, HBV control and vaccination. The outputs of the project were reported through peer-reviewed publications and modelling– based and science-informed public policy recommendations

Emerg Infect Dis

PMC4550154611

Emerging infectious diseases

Emerging Infectious Diseases is providing access to these abstracts on behalf of the ICEID 2012 program committee (www.iceid.org), which performed peer review. Emerging Infectious Diseases has not edited or proofread these materials and is not responsible for inaccuracies or omissions. All information is subject to change. Comments and corrections should be brought to the attention of the authors.Influenza preparedness: lessons learned -- Policy implications and infectious diseases -- Improving preparedness for infectious diseases -- New or rapid diagnostics -- Foodborne and waterborne infections -- Effective and sustainable surveillance platforms -- Healthcare-associated infections -- Molecular epidemiology -- Antimicrobial resistance -- Tropical infections and parasitic diseases -- H1N1 influenza -- Risk Assessment -- Laboratory Support -- Zoonotic and Animal Diseases -- Viral Hepatitis -- E1. Zoonotic and animal diseases -- E2. Vaccine issues -- E3. H1N1 influenza -- E4. Novel surveillance systems -- E5. Antimicrobial resistance -- E6. Late-breakers I -- Antimicrobial resistance -- Influenza preparedness: lessons learned -- Zoonotic and animal diseases -- Improving preparedness for infectious diseases -- Laboratory support -- Early warning systems -- H1N1 influenza -- Policy implications and infectious diseases -- Modeling -- Molecular epidemiology -- Novel surveillance systems -- Tropical infections and parasitic diseases -- Strengthening public health systems -- Immigrant and refugee health -- Foodborne and waterborne infections -- Healthcare-associated infections -- Foodborne and waterborne infections -- New or rapid diagnostics -- Improving global health equity for infectious diseases -- Vulnerable populations -- Novel agents of public health importance -- Influenza preparedness: lessons learned -- Molecular epidemiology -- Zoonotic and animal diseases -- Vaccine-preventable diseases -- Outbreak investigation: lab and epi response -- H1N1 influenza -- laboratory support -- effective and sustainable surveillance platforms -- new vaccines -- vector-borne diseases and climate change -- travelers' health -- J1. Vectorborne diseases and climate change -- J2. Policy implications and infectious diseases -- J3. Influenza preparedness: lessons learned -- J4. Effective and sustainable surveillance platforms -- J5. Outbreak investigation: lab and epi response I -- J6. Late-breakers II -- Strengthening public health systems -- Bacterial/viral coinfections -- H1N1 influenza -- Novel agents of public health importance -- Foodborne and waterborne infections -- New challenges for old vaccines -- Vectorborne diseases and climate change -- Novel surveillance systems -- Geographic information systems (GIS) -- Improving global health equity for infectious diseases -- Vaccine preventable diseases -- Vulnerable populations -- Laboratory support -- Prevention challenges for respiratory diseases -- Zoonotic and animal diseases -- Outbreak investigation: lab and epi response -- Vectorborne diseases and climate change -- Outbreak investigation: lab and epi response -- Laboratory proficiency testing/quality assurance -- Effective and sustainable surveillance platforms -- Sexually transmitted diseases -- H1N1 influenza -- Surveillance of vaccine-preventable diseases -- Foodborne and waterborne infections -- Role of health communication -- Emerging opportunistic infections -- Host and microbial genetics -- Respiratory infections in special populations -- Zoonotic and animal diseases -- Laboratory support -- Antimicrobial resistance -- Vulnerable populations -- Global vaccine initiatives -- Tuberculosis -- Prevention challenges for respiratory diseases -- Infectious causes of chronic diseases -- O1. Outbreak investigation: lab and epi response II -- O2. Prevention challenges for respiratory diseases -- O3. Populations at high risk for infectious diseases -- O4. Foodborne and waterborne infections -- O5. Laboratory support: surveillance and monitoring infections -- O6. Late-breakers IIIAbstracts published in advance of the conference

A three-pronged approach to virus discovery

Rodents and bats are two key groups of host species for viral diversity and zoonotic transmission to humans. Whilst the use of NGS and PCR based virus discovery is improving our collective knowledge of the virome, very little is known about the virome overall, and even less is known about the specific virome of these mammalian hosts. Similarly, information is lacking regarding the prevalence of viruses within UK rodents. As climate change progresses and rodents are driven into closer proximity to humans and livestock, the risk of rodent zoonotic transmission is increasing, increasing the risk of transmission of viruses with pandemic potential. Evolutionary information about key viruses may help to improve pandemic preparedness, but the field of historic virology is still relatively underdeveloped, particularly regarding historic RNA virus investigations. Therefore, this project was designed to take a three-pronged approach to investigating virus diversity within UK rodents via degenerate PCR and NGS screening, and to advance the field of historic RNA virus discovery. 140 modern rodents from 5 species were screened by degenerate PCR for the presence of adenoviruses, hantaviruses, coronaviruses, Rotaviruses and Rubiviruses. 2 adenoviruses and 1 hantavirus were identified, and all other viruses were not found in. This screening was complemented by unbiased NGS sequencing of these rodents and analysis of the NGS data. The metagenomics screening yielded a total of 216 viral hits across 19 viral genera, including potentially important viruses such as Cardioviruses, Hepaciviruses and hantaviruses, amongst others. These viruses were PCR confirmed, and expanded the known viral diversity of bank voles, field voles, wood mice and yellow-necked mice to include Picobirnaviruses, Kunsaigiviruses, Rosaviruse, Pegiviruses, Bocaparvoviruses and polyomaviruses. Hepacivirus F, Rosaviruses and Orbiviruses were also found in the UK for the first time, and accurate abundance estimates for 19 viral genera were quantified, ranging from 0.7%-67.1%. Collectively, this drastically improves our collective knowledge of the UK virome. This project also advanced the techniques used for historic RNA virus discovery and manipulation. A protocol for historic RNA extraction from preserved animals ranging from at least 35-156 years old was developed with over 90% extraction success. NGS library preparation processes were improved to yielded functional NGS libraries, albeit with substantial adaptor dimer contamination. qPCR screening methods for historic coronaviruses were also developed, and historic coronaviruses were found in 3 samples. Collectively, this advances the methodology and techniques of historic RNA virus discovery, and shows as a proof of concept that conventional screening methods can be used for the discovery of historic viruses in well preserved samples