Yellow fever is an infectious disease transmitted by the bite of infected Aedes aegypti, as well as other types of Aedes and Haemagogus mosquitoes. These mostly bite during the day and breed in both urban and rural areas.
Yellow fever is a vaccine-preventable disease, and a single dose provides life-long protection. The World Health Organization considers yellow fever a global health security threat due to its history of international spread.
The disease is endemic in 34 countries in Africa and 13 countries in Central and South America and is responsible for between 29,000 to 60,000 deaths a year.
Yellow fever symptoms usually appear three to six days after someone is bitten by an infected mosquito, but sometimes take longer to appear. Many people do not experience any symptoms. Initial symptoms may be similar to the flu and can include:
These symptoms often last for three or four days. The disease can be hard to diagnose, particularly in the early stages.
A small percentage of people experience a second phase within 24 hours of recovering from the initial symptoms. High fever returns, and several body systems are affected, particularly the liver and kidneys.
The more serious symptoms of yellow fever can be fatal. Up to half of those who enter the toxic phase die within seven to 10 days. Liver or kidney damage can also occur.
Yellow fever is transmitted to humans primarily through the bite of infected mosquitoes. In forested areas, yellow fever virus primarily circulates between mosquitoes and animals, such as monkeys. People can become infected when visiting or working in forested areas where the virus is circulating. In the urban environment, the virus primarily circulates between mosquitoes and people. It does not spread directly between humans – that is through contact – but humans can transmit the virus to mosquitoes.
The virus can spread rapidly in urban areas with a high density of mosquitoes and a lack of immunity in the population.
There is no specific antiviral drug for yellow fever. Treatment focuses on relieving symptoms, including resting, staying hydrated, and seeking medical advice. Painkillers such as paracetamol or ibuprofen can help to lower temperature and relieve muscle pain. Treatment for dehydration, liver and kidney failure, and fever improves outcomes. People with serious symptoms need to be treated in hospital immediately.
Yellow fever can be easily prevented by vaccination and a single dose provides life-long protection. It is recommended for people travelling to areas where yellow fever is found. Other preventive measures include avoiding mosquito bites by wearing long-sleeved clothing and trousers, using insect repellent, closing windows and doors, and sleeping under insecticide-treated mosquito nets. Ensuring mosquitoes cannot breed in standing water is also important.
Scientists have also reported success with introducing a bacteria called Wolbachia into Aedes mosquitoes – this was first developed to block the mosquito’s ability to transmit dengue, but works for other diseases including yellow fever.
There have been outbreaks of yellow fever throughout history – it temporarily halted the construction of the Panama canal and in 1878 an outbreak in the Mississippi valley killed around 20,000 people.
In 1927 British bacteriologist Adrian Stokes discovered the yellow fever virus then Max Theiler of the Rockefeller Foundation developed a live form of the virus which was used as a vaccine. A form of this vaccine is still used today – one dose confers lifelong immunity, making it one of the most effective vaccines.
In 2015 and 2016 there was an outbreak of the disease in Angola, which spread to the Democratic Republic of Congo and other countries in Africa. A traveller imported the disease to China – the first ever case of the disease here. This outbreak prompted the World Health Organization to step up efforts to eliminate the disease.
who.int/fact-sheets/yellow-fever
gavi.org/vaccine-profile/yellow-fever
Protect yourself and your family by learning more about Global Health Security
此内容由惯性聚合(RSS阅读器)自动聚合整理，仅供阅读参考。 原文来自 — 版权归原作者所有。