Yellow Fever Strikes Angola

The World Health Organization (WHO) has reported that 16 of the 18 provinces in Angola have reported Yellow Fever infection. As of late March, there have been a total of 1,132 suspected and confirmed yellow fever cases in the country, with 168 deaths, the majority of which have been reported in Luanda.

Since early February, Angola’s Ministry of Health and WHO have been collaborating in an effort to control the number of infections by implementing an emergency vaccine campaign in Luanda. Travel to Angola is also being regulated: anyone older than 9 months of age is required to have the proper paperwork to prove they have received a yellow fever vaccination prior to arrival in Angola, regardless of their country of origin.

About the Yellow Fever Vaccine

Most individuals only need one dose of the yellow fever vaccine, but some individuals can develop a fatal allergic reaction, thus the Centers for Disease Control and Prevention (CDC) has advised that individuals should be tested prior to vaccine administration. Vaccines are not recommended for those receiving immunosuppressive and immunomodulatory therapies or transplants. Furthermore, those with primary immunodeficiencies, or malignant neoplasms, are advised not to receive vaccine. If an individual is pregnant or breastfeeding, she should contact her healthcare provider before receiving any vaccines.

How is Yellow Fever Transmitted?

Yellow fever is a flavivirus and can be found in the tropical and subtropical regions of South America and Africa. The virus can be transmitted through the bite of an Aedes or Haemagogus mosquito which was infected by either a human or non-human carrier of the disease. There are three transmission cycles of yellow fever:

• The Jungle, or Sylvatic cycle: in which the virus is transferred between infected creatures (whether from human to human, animal to animal, human to animal, or animal to human) by a mosquito species found in the forest canopy. Humans who live or work in a jungle are at risk of contracting yellow fever through this transmission cycle.
• The Savannah cycle: in which the virus is transmitted between two humans or an animal and a human, through the bite of an infected mosquito. This transmission cycle is specific to African jungle areas.
• The Urban cycle: in which the virus is transmitted between humans by urban Aedes aegypti mosquitos. Since the yellow fever virus originates in tropic or subtropical regions, the urban cycle involves the transmission of the virus from individual who originally acquired infection in a jungle or savannah, to an urban mosquito.

What are the Symptoms of Yellow Fever?

Although the majority of individuals who contract yellow fever do not show symptoms, some develop:

• Fever
• Chills
• Severe headache
• Back pain
• General body aches
• Nausea and vomiting
• Fatigue
• Weakness

Around 15% of infected individuals develop severe forms of the disease, in which they exhibit high fever, jaundice, bleeding, shock, or multiple organ failure. Those who develop these symptoms should be put under close observation, preferably in a hospital setting. Twenty to 50% of patients with severe yellow fever die; however, those who survive yellow fever develop an immunity to it.

There is currently no treatment specific to yellow fever, and so infected individuals are advised to rest, drink lots of fluids, and use pain relievers to alleviate mild symptoms; however, certain anti-inflammatory medications should be avoided, such as aspirin, ibuprofen or naproxen.

Recommendations on Travel to Angola

The CDC recommends that individuals traveling to Angola receive the vaccination at least 10 days prior to travel and obtain a signed and stamped International Certificate of Vaccination or Prophylaxis (ICVP), or yellow card, which needs to be presented at an Angolan airport upon arrival. Those individuals over 60 years of age, as well as those with immunodeficiencies, are at high risk of developing adverse effects to the yellow fever vaccine and should contact their primary healthcare providers prior to receiving the vaccination.

As with most vector-borne diseases, individuals traveling to infected regions are advised to take the necessary steps to prevent infection. The CDC recommends that individuals refrain from wearing exposing clothing to avoid mosquito bites, as well as use EPA-registered insect repellents.

WHO Response to Yellow Fever in Angola

The yellow fever outbreak was declared a “grade 2 emergency” by WHO in February 2016, in accordance with the Emergency Response Framework (ERF). Of the 12 targeted municipalities, individuals in 6 municipalities have thus far received vaccinations. Three of the 6 municipalities which received vaccinations have reported approximately 90% vaccination rates in the population.

WHO reports that yellow fever transmission is still active among the unvaccinated population in Luanda and other regions of Angola. In addition, there have been documented reports of the spread of yellow fever in travelers from Angola to China (8 cases), Kenya (2 cases), and the Democratic Republic of Congo, however, these imported cases do not constitute an outbreak in the respective countries.