Yellow fever in China is still an imported disease

Chen, Jun; Lu, Hongzhou

doi:10.5582/bst.2016.01051

Cited by 17 publications

(10 citation statements)

References 21 publications

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“… 7 The present ease and frequency of international travel, compounded by poor enforcement of travel vaccination requirements, low levels of vaccination coverage in many at-risk regions, 16 and existing vaccine shortages, raise serious concerns of introduction of yellow fever virus into naive human populations, particularly in southern Asia. 8 …”

Section: Discussionmentioning

confidence: 99%

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Existing and potential infection risk zones of yellow fever worldwide: a modelling analysis

Shearer

Longbottom

Browne

et al. 2018

The Lancet Global Health

113

121

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SummaryBackgroundYellow fever cases are under-reported and the exact distribution of the disease is unknown. An effective vaccine is available but more information is needed about which populations within risk zones should be targeted to implement interventions. Substantial outbreaks of yellow fever in Angola, Democratic Republic of the Congo, and Brazil, coupled with the global expansion of the range of its main urban vector, Aedes aegypti, suggest that yellow fever has the propensity to spread further internationally. The aim of this study was to estimate the disease's contemporary distribution and potential for spread into new areas to help inform optimal control and prevention strategies.MethodsWe assembled 1155 geographical records of yellow fever virus infection in people from 1970 to 2016. We used a Poisson point process boosted regression tree model that explicitly incorporated environmental and biological explanatory covariates, vaccination coverage, and spatial variability in disease reporting rates to predict the relative risk of apparent yellow fever virus infection at a 5 × 5 km resolution across all risk zones (47 countries across the Americas and Africa). We also used the fitted model to predict the receptivity of areas outside at-risk zones to the introduction or reintroduction of yellow fever transmission. By use of previously published estimates of annual national case numbers, we used the model to map subnational variation in incidence of yellow fever across at-risk countries and to estimate the number of cases averted by vaccination worldwide.FindingsSubstantial international and subnational spatial variation exists in relative risk and incidence of yellow fever as well as varied success of vaccination in reducing incidence in several high-risk regions, including Brazil, Cameroon, and Togo. Areas with the highest predicted average annual case numbers include large parts of Nigeria, the Democratic Republic of the Congo, and South Sudan, where vaccination coverage in 2016 was estimated to be substantially less than the recommended threshold to prevent outbreaks. Overall, we estimated that vaccination coverage levels achieved by 2016 avert between 94 336 and 118 500 cases of yellow fever annually within risk zones, on the basis of conservative and optimistic vaccination scenarios. The areas outside at-risk regions with predicted high receptivity to yellow fever transmission (eg, parts of Malaysia, Indonesia, and Thailand) were less extensive than the distribution of the main urban vector, A aegypti, with low receptivity to yellow fever transmission in southern China, where A aegypti is known to occur.InterpretationOur results provide the evidence base for targeting vaccination campaigns within risk zones, as well as emphasising their high effectiveness. Our study highlights areas where public health authorities should be most vigilant for potential spread or importation events.FundingBill & Melinda Gates Foundation.

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Section: Discussionmentioning

confidence: 99%

“… 7 Fortunately, these importation events occurred in Beijing, Shanghai, and Fujian, where A aegypti is not established, and no secondary cases resulting from local transmission were detected. 8 …”

Section: Introductionmentioning

confidence: 99%

Existing and potential infection risk zones of yellow fever worldwide: a modelling analysis

Shearer

Longbottom

Browne

et al. 2018

The Lancet Global Health

113

121

View full text Add to dashboard Cite

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“…In the sylvatic “jungle cycle”, monkeys act as the host and Aedes africanus and other Aedes spp. are the vectors (Chen and Lu 2016 ).…”

Section: Mosquito-borne Viruses Pathogenic To Humans or Animalsmentioning

confidence: 99%

“…All the patients had traveled back to China from Angola. Although no local case of yellow fever has been reported, with the growing migration in southern China, where the Aedes aegypti density is relatively high, there is an increased risk of autochthonous transmission in this region (Chen and Lu 2016 ). The main strategies for control of yellow fever transmission in China entail continuous screening, control of vectors, vaccination of travelers that are going to yellow fever endemic regions, and strengthening of public education.…”

Section: Mosquito-borne Viruses Pathogenic To Humans or Animalsmentioning

confidence: 99%

Mosquito-Associated Viruses in China

et al. 2018

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Mosquitoes are classified into approximately 3500 species and further grouped into 41 genera. Epidemiologically, they are considered to be among the most important disease vectors in the world and they can harbor a wide variety of viruses. Several mosquito viruses are considered to be of significant medical importance and can cause serious public health issues throughout the world. Such viruses are Japanese encephalitis virus (JEV), dengue virus (DENV), chikungunya virus (CHIKV), and Zika virus (ZIKV). Others are the newly recognized mosquito viruses such as Banna virus (BAV) and Yunnan orbivirus (YNOV) with unclear medical significance. The remaining mosquito viruses are those that naturally infect mosquitoes but do not appear to infect humans or other vertebrates. With the continuous development and improvement of mosquito and mosquito-associated virus surveillance systems in China, many novel mosquito-associated viruses have been discovered in recent years. This review aims to systematically outline the history, characteristics, distribution, and/or current epidemic status of mosquito-associated viruses in China.

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“…Despite the Angola not having a locally acquired case in over a decade, the outbreak in 2015 spread to neighbouring countries, as well as China. (Chen & Lu, 2016;WHO, 2016). Brazil also suffered a prolonged outbreak from 2016 to 2018 that killed 700 people even though yellow fever had not been registered for decades, and cases have continued to be reported in Brazil, Bolivia and Peru (UNICEF, 2019).…”

Section: Results: Vaccination Borders and Reaching International Agrmentioning

confidence: 99%

Travel restrictions as a disease control measure: Lessons from yellow fever

Vanderslott

Marks

2020

Global Public Health

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Travel restrictions have become a common disease control measure during the 2019 Coronavirus disease pandemic (COVID-19). Measures have ranged from quarantines when entering a country to outright travel bans. Yet more widespread travel restrictions in the form of country vaccine entry requirements have been in place for a long time for another diseaseyellow fever. We track the historical underpinnings and policy developments that have led to stringent vaccine entry requirements today. We also discuss the political issues raised by health measures imposed on borders and discuss the reasons behind some clear regional differences. Almost no European countries currently have vaccine entry requirements, while at the other end of the spectrum, the majority of countries in the African region do, making vaccine entry requirements a global south phenomenon. We argue that vaccine entry requirements should be reassessed in the future as an underused public health tool, likely to become increasingly common. Vaccine entry requirements have proved effective in controlling the international spread of yellow fever but more can be done to ensure better use of this measure. Caution is needed due to the close links between public health and politics, evident since the first travel restriction in quarantines.

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Yellow fever in China is still an imported disease

Cited by 17 publications

References 21 publications

Existing and potential infection risk zones of yellow fever worldwide: a modelling analysis

Existing and potential infection risk zones of yellow fever worldwide: a modelling analysis

Mosquito-Associated Viruses in China

Travel restrictions as a disease control measure: Lessons from yellow fever

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