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Introduction: Yellow fever is caused by an RNA flavivirus. Immunisation in conjunction with vector control is at the forefront of yellow fever control and elimination. Objective: This narrative review describes the impact and importance of yellow fever vaccinations for northern Australian health practitioners. Design: Selected key policies, studies and medical guidelines are reviewed and presented. Finding: Large yellow fever outbreaks, associated with vector spread, have occurred in the last decade in Africa and South America, increasing the risk of international spread of the virus. Mobile populations, like travellers or migrant workers, continue to be at risk of yellow fever. Quality assurance, including yellow fever centre accreditation and initiatives to decrease fraudulent yellow fever vaccination documentation, has evolved in the past few years. Fractional dosing of yellow fever vaccines has been shown to provide protection for 1 year in outbreak scenarios, but further studies are needed. Discussion: Although Australia is yellow fever‐free, the disease could be introduced by viraemic persons as a competent Aedes mosquito vector is present in northern Australia. In addition to surveillance and vector control, health education and yellow fever vaccination remain the best lines of defence. In the event of an outbreak, a response via fractional dosing could prove to be effective in controlling the virus. Conclusion: Health care providers in northern Australia should be aware of the risks of yellow fever and its introduction to northern Australia and be able to discuss vaccination status with their clients when needed. [ABSTRACT FROM AUTHOR]

An editorial is presented on the treatment and control of yellow fever in Brazil. Topics mentioned include the effort of the government of Brazil to manage the yellow fever outbreak in the country, the monitoring of epizootics in the country to detect the circulation of the virus, and the relation of yellow fever to changes in social structure and climate change.

In common with Zika, Chikungunya and Dengue, Yellow Fever (YF) is an arthropod-borne flavivirus. It is transmitted between humans and from monkeys by mosquitoes of the Aedes aegypti (its principal vector), haemogogus and albopictus varieties. Three cycles of transmission may occur: urban; sylvatic; and intermediate. Recently, sub-Saharan Africa has seen the resurgence of this neglected disease. The current YF outbreak in Angola began in December 2015 in the capital Luanda and by October 2016 there had been > 4300 suspected cases, with 376 deaths (case fatality rate = 8.8%). A total of 884 were laboratory confirmed but it is likely that case numbers may be seriously underestimated. YF has subsequently quickly spread to neighbouring Congo and further afield to Kenya and also China, this being of grave concern as this was a first introduction of YF to Asia. YF has recently hit Brazil, with 555 suspected cases and 107 deaths reported by the end of January 2017. Extremely rapid unplanned urban migration in Africa by non-immune rural populations to already densely populated cities, where high densities of mosquitoes co-exist with city dwellers in makeshift flimsy accommodation, poses a ready recipe for an epidemic of massive proportion. In such conditions, with enormously strained public services existing among the most needy and vulnerable populations, mosquito control programmes are nearly impossible. YF in Congo is a tempest barely restrained. However, it is one that can be controlled by focused and committed international collaboration, by intense and united political will and by the marriage of old and trusted techniques: a vaccine almost a century old and some of the most modern technologies available to man. [ABSTRACT FROM AUTHOR]

Background: The ongoing yellow fever epidemic in Angola strains the global vaccine supply, prompting WHO to adopt dose sparing for its vaccination campaign in Kinshasa, Democratic Republic of the Congo, in July-August, 2016. Although a 5-fold fractional-dose vaccine is similar to standard-dose vaccine in safety and immunogenicity, efficacy is untested. There is an urgent need to ensure the robustness of fractional-dose vaccination by elucidation of the conditions under which dose fractionation would reduce transmission.Methods: We estimate the effective reproductive number for yellow fever in Angola using disease natural history and case report data. With simple mathematical models of yellow fever transmission, we calculate the infection attack rate (the proportion of population infected over the course of an epidemic) with various levels of transmissibility and 5-fold fractional-dose vaccine efficacy for two vaccination scenarios, ie, random vaccination in a hypothetical population that is completely susceptible, and the Kinshasa vaccination campaign in July-August, 2016, with different age cutoff for fractional-dose vaccines.Findings: We estimate the effective reproductive number early in the Angola outbreak was between 5·2 and 7·1. If vaccine action is all-or-nothing (ie, a proportion of vaccine recipients receive complete protection [VE] and the remainder receive no protection), n-fold fractionation can greatly reduce infection attack rate as long as VE exceeds 1/n. This benefit threshold becomes more stringent if vaccine action is leaky (ie, the susceptibility of each vaccine recipient is reduced by a factor that is equal to the vaccine efficacy). The age cutoff for fractional-dose vaccines chosen by WHO for the Kinshasa vaccination campaign (2 years) provides the largest reduction in infection attack rate if the efficacy of 5-fold fractional-dose vaccines exceeds 20%.Interpretation: Dose fractionation is an effective strategy for reduction of the infection attack rate that would be robust with a large margin for error in case fractional-dose VE is lower than expected.Funding: NIH-MIDAS, HMRF-Hong Kong. [ABSTRACT FROM AUTHOR]

Yellow fever virus (YFV) is the prototypical hemorrhagic fever virus, yet our understanding of its phenotypic diversity and any molecular basis for observed differences in disease severity and epidemiology is lacking, when compared to other arthropod-borne and haemorrhagic fever viruses. This is, in part, due to the availability of safe and effective vaccines resulting in basic YFV research taking a back seat to those viruses for which no effective vaccine occurs. However, regular outbreaks occur in endemic areas, and the spread of the virus to new, previously unaffected, areas is possible. Analysis of isolates from endemic areas reveals a strong geographic association for major genotypes, and recent epidemics have demonstrated the emergence of novel sequence variants. This review aims to outline the current understanding of YFV genetic and phenotypic diversity and its sources, as well as the available animal models for characterizing these differences in vivo . The consequences of genetic diversity for detection and diagnosis of yellow fever and development of new vaccines and therapeutics are discussed. [ABSTRACT FROM AUTHOR]

Highlights: [•] Humanized MAb is effective for yellow fever (YF) immunotherapy in a hamster model. [•] Treatment with 380 or 38μg MAb 24h prior to YFV challenge improves survival. [•] MAb given up to 3days post-challenge results in significant survival rates. [•] MAb therapeutic efficacy is improved in an immunocompetent animal model. [ABSTRACT FROM AUTHOR]

In April 2016, a yellow fever outbreak was detected in Uganda. Removal of contaminating ribosomal RNA in a clinical sample improved the sensitivity of next-generation sequencing. Molecular analyses determined the Uganda yellow fever outbreak was distinct from the concurrent yellow fever outbreak in Angola, improving our understanding of yellow fever epidemiology. [ABSTRACT FROM AUTHOR]

The article offers information on yellow fever, which refers to a hemorrhagic and lethal RNA virus that caused an outbreak in Angola, Democratic Republic of Congo and Uganda. Topics covered include the transmission and infection of yellow fever, the clinical manifestations of the disease and the care for patients with yellow fever. Also mentioned are the tools used for diagnosis such as serology and immunocytochemistry.