Currently, there is a particularly worrisome yellow fever outbreak in Angola due to the increasing number of cases, a vaccine shortage, and another simultaneous mosquito-disease epidemic. Angola is experiencing its worst yellow fever outbreak in the last 30 years (1). So far, the yellow fever death toll in Angola has reached 250, with the number of reported cases has reached 1,908 as of April 20th (6, 7). The virus has hit 16 of the 18 provinces in Angola and is continuing to spread to other provinces and countries (1). Imported cases of the virus from Angola have been reported in China, the Democratic Republic of Congo, and Kenya (2).
What is Yellow Fever?
Yellow Fever is mosquito-borne virus that is endemic in tropical areas of Latin America and Africa (5). The virus is transmitted by two types of mosquitoes, the Aedes aegypti and Haemagogus mosquitoes (5). The Aedes aegypti is the same mosquito that transmits Zika virus and dengue fever (2). The mosquitoes contract the virus primarily from monkeys and then are able to transmit the virus to humans (5). “Yellow” in ‘Yellow Fever’ refers to the jaundice that occurs in some patients as a result of the virus (5).
Upon initial infection, the virus incubates in the body for 3-6 days. The virus occurs in two phases -- the first phase is the “acute” phase and causes symptoms of fever, muscle pain, back pain, headache, shivers, lack of appetite, and nausea or vomiting (5). The majority of people affected by the acute phase improve and recover after 3-4 days from the onset of symptoms (5).
However, 15% of infected patients do not improve from the acute phase and enter into the second and more dangerous phase of the virus -- the toxic phase (5). This phase occurs within 24 hours of the initial remission of the virus (5). Common symptoms of the toxic phase include high fever, jaundice, abdominal pain and vomiting, kidney function deterioration, and bleeding from the mouth, nose, eyes, or stomach (5). When this bleeding happens, bloody vomit and feces can also occur (5). Only 50% of patients who reach the toxic phase of the virus survive and those who do not survive, die within 10-14 days (5). Those who are lucky enough to survive can recover without severe organ damage (5).
There is no specialized treatment for Yellow Fever (5). A patient can receive supportive care that treats dehydration, respiratory failure, and fever but this is often not readily available in poorer areas (5). The most important measure to prevent the outbreak of this virus is vaccination (5). The Yellow Fever vaccine has found to be 90% effective in people within 10 days of receiving the vaccination and 99% effective in people within 30 days of receiving the vaccination (5). Mosquito control and epidemic preparedness and response are also necessary methods of control and prevention. However, lack of effective mosquito control and appropriate epidemic preparedness and response have been major contributing factors to the alarming outbreak in Angola.
The Vaccine Shortage
The current outbreak began in the province of Luanda, the capital of Angola and the majority of the cases are still being reported within that area (2). To control this epidemic, Angola’s Ministry of Health and the World Health Organization launched an emergency vaccination campaign in Luanda province in February with plans to vaccinate 6.5 million people (3,4). Vaccination is the best known method of prevention of Yellow Fever and is necessary to stop this continuous outbreak.
However, an extreme shortage of the vaccine has been a major concern for this epidemic. The World Health Organization exhausted its emergency stockpile of the Yellow Fever vaccine and still needed to vaccinate 1.5 million people in Luanda alone (2). Additionally, there are only four facilities globally that produce the yellow fever vaccine (4). These four facilities will be challenged to effectively meet the continuing supply and demand of the vaccines needed to address this outbreak. With the emergency stockpile completely empty, more emphasis on producing the yellow fever vaccine has been prioritized (4). Some studies have shown that using one-fifth or one-tenth of the current vaccination dose may protect people against the disease, which could provide an alternative solution to the vaccine shortage issue (4). The effectiveness of that possible solution remains to be determined, but may be a better alternative for prevention and protection.
Given the recent vaccination shortage and the continuous spread of the virus to other countries, many health experts fear this outbreak will become uncontrollable (4). The virus’ spread to Asia is the most alarming concern because there may not be enough vaccines to treat Angola’s population and other possible outbreaks in Africa and Asia. Vaccine manufacturers are attempting to increase productivity in the making of the vaccine and will continue to ship vaccines where they are needed (2). Additionally, Angola has put a ban on visitors aged 9 months and older allowed into the country without proper vaccination (3). People who wish to travel to Angola during this time must show proof of proper vaccination.
Replenishment of the Emergency Supply
Thankfully, at the end of March 2016, the emergency vaccine supply was replenished to include 10 million vaccines available to prevent yellow fever (6). This new supply will greatly contribute to effectively controlling the further spread of yellow fever in Angola. However, there is still a concern with regards to potential spread in other parts of Africa and Asia and whether further vaccination production, in addition to the replenished supply, should be prioritized.
- Gaffey, C. (2016, April 16). Angola: Yellow Fever Death Toll Rise to 225 Amid Vaccine Shortage. Newsweek. Retrieved April 25, 2016, from http://www.newsweek.com/angola-yellow-fever-death-toll-rise-225-amid-vac...
- Goldschmidt, D. (2016, March 25). Yellow fever vaccine shortage as outbreak in Angola spreads. CNN. Retrieved April 25, 2016, from http://www.cnn.com/2016/03/25/health/yellow-fever-vaccine-shortage-angola/
- Yellow Fever in Angola. (n.d.). Retrieved April 25, 2016, from http://wwwnc.cdc.gov/travel/notices/alert/yellow-fever-angola
- Kupferschmidt, K. (2016). Angolan yellow fever outbreak highlights dangerous vaccine shortage. Science. doi:10.1126/science.aaf4082
- Yellow fever. (n.d.). Retrieved April 25, 2016, from http://www.who.int/mediacentre/factsheets/fs100/en/
- Angola' health officials extend vaccination campaign for yellow fever to Huambo and Benguela provinces. (2016, April 21). News Medical. Retrieved April 25, 2016, from http://www.news-medical.net/news/20160421/Angola-health-officials-extend-vaccination-campaign-for-yellow-fever-to-Huambo-and-Benguela-provinces.aspx
- Yellow fever outbreak in Angola: Vaccination campaigns to extend to Huambo and Benguela provinces. (2016, April 20). Outbreak News Today. Retrieved April 25, 2016, from http://outbreaknewstoday.com/yellow-fever-outbreak-in-angola-vaccination...