WHO | Yellow Fever – Uganda

From November 4 to February 14, 2020, eight laboratory confirmed cases of yellow fever in Buliisa (3), Maracha (1) and Moyo (4); including four deaths (CFR 50%) were detected through the national surveillance system.

On December 10, 2019, the Ministry of Health (MoH) notified the Uganda Virus Regional Reference Laboratory (UVRI) of the yellow fever case, confirmed by polymerase reverse transcriptase (RT-PCR) chain reaction. The case was a 37-year-old man with suspected viral haemorrhagic fever (VHF). His occupation was cattle breeding with a history of traveling the dairy trade between the Kizikya cell, Uganda’s Buliisa district and the Democratic Republic of the Congo (DRC). On October 30, 2019, he presented at a hospital with symptoms of fever and headache for five days. His symptoms were exacerbated by vomiting, abdominal pain and epistaxis, and he died on November 4, 2019. During an in-depth investigation in December, eight samples were collected from close contacts, including family members and neighbors and tested for yellow fever. On January 22, 2020, UVRI notified the MoH of a second yellow fever case, confirmed by serological testing (IgM and PRNT) in Buliisi, in connection with an index case and a similar occupation. Other samples collected during the test had a negative effect on yellow fever.

Two confirmed cases of yellow fever have been identified in Moyo district in the West Nile region, which shares the border with South Sudan. The cases are 18 and 21 years old, they trade timber between Uganda and South Sudan and spend time in both countries. The illness in both cases was January 3, 2020, and they were admitted to Moyo County Health Center. They were later referred to General Hospital with symptoms of fever, vomiting, diarrhea, fatigue, headache, abdominal and joint pain, confusion and unexplained bleeding. The cases worsened and died at the hospital on January 5-6, 2020. UVRI results were confirmed by RT-PCR infection with yellow fever performed at UVRI.

Subsequently, Moyo County reported a second set of suspected and confirmed yellow fever infections in another village. The confirmed case in the suspected group was a 59-year-old patient who presented with symptoms including unexplained bleeding and fever on January 22, and died January 23, 2020. Blood sample positive for yellow fever by RT-PCR at UVRI. He was preceded in death by two members of his family in early January with similar symptoms.

The Uganda Government Minister of Health declared the yellow fever epidemic on January 23, 2020.

After the outbreak was declared, three additional cases were confirmed in Buliisa (1), Moyo (1) and Maracha (1). A detailed investigation of these cases is ongoing.

Public health response

National Rapid Response Teams have been deployed in Moyo and Buliisa counties to conduct further investigations and launch responses to the epidemic. Other response activities include: enhanced surveillance and active case finding in all districts of the northwest region, and entomological testing in the affected districts of Buliisa and Moyo. Cross-border notification with South Sudan regarding cases in Moyo district has been made. Investigations are ongoing in DRC and South Sudan and WHO AFRO supports coordination.

The Ministry of Health is planning a reactive campaign approved by the International Coordinating Group on the provision of vaccines to control yellow fever. This reactive campaign will target an estimated 1.7 million people to stop transmission and prevent the immediate risk of outbreaks in the northwestern part of the country, especially in Buliisa, Koboko, Maracha, Moyo and Yumbe counties. In order to achieve lasting protection across the country, the Ministry of Health is preparing to apply for the introduction of yellow fever vaccination into a routine immunization program in 2021 and to carry out preventive mass vaccination campaigns nationally.

WHO risk assessment

Yellow fever is an acute viral hemorrhagic disease transmitted by infected mosquitoes and can spread rapidly and cause serious public health impact. Uganda is classified as a high-risk country in the Eliminate Yellow Fever Outbreaks (EYE) initiative, with a history of recent epidemics in 2019, 2018, 2016 and 2011. The epidemic spread of yellow fever is a risk in Uganda as estimated overall. population immunity is low (4.2%), which can be attributed to past reactive vaccination activities in focal districts not affected by the current epidemic.

Due to the negligible immunity of the population in the affected neighborhoods, detection of yellow fever cases is a concern. The affected districts share international borders with the DRC and South Sudan; and are characterized by frequent population movements and great interconnectedness. Population immunity for yellow fever in cross-border areas is also low and the forest biome between countries is continuous, indicating that there is a risk of international spread. Close monitoring of the situation with active cross-border coordination and exchange of information is needed as the possibility of cases in neighboring countries and the risk of spread to the DRC and South Sudan cannot be completely ruled out.

Tip of WHO

Vaccination is an essential means of preventing and controlling yellow fever and provides immunity for life. In urban centers, targeted vector control measures are also helpful in interrupting transmission. The country plans to introduce yellow fever vaccination into a routine immunization program and complete preventative mass vaccinations to quickly increase population immunity. Accelerated planning and implementation of these population protection activities will help prevent future epidemics.

WHO recommends vaccination against yellow fever for all international travelers aged 9 months and older going to Uganda as there is evidence of persistent or periodic transmission of yellow fever virus. Yellow fever vaccination is safe, highly effective and provides lifelong protection. However, vaccination with yellow fever is not recommended for infants between the ages of 6 and 8 months, except during epidemics where the risk of transmitting the yellow fever virus can be very high. The risks and benefits of vaccination in this age group should be carefully considered before vaccination. The vaccine should be used with caution during pregnancy or breast-feeding. However, pregnant or lactating women may be vaccinated during epidemics or if a trip to a country or area at risk of transmission is inevitable. Uganda also requires a valid yellow fever vaccination certificate for travelers aged 1 and over as a condition of entry.

In accordance with International Health Regulations (2005) Third Edition, the international certificate of vaccination against yellow fever is valid for 10 days after vaccination and during the life of the vaccinated person. One dose of WHO-approved yellow fever vaccine is sufficient to provide sustained immunity and lifelong protection against yellow fever disease. No increased vaccine dose is required and international travelers are not required as a condition of entry.

The WHO encourages its Member States to take all necessary steps to ensure that passengers are well informed about the risks and preventative measures, including vaccination. As a general precaution, the WHO also recommends avoiding mosquito bites. The highest risk for yellow fever virus transmission is during the day and in the early evening. Travelers should be aware of the signs and symptoms of yellow fever and instruct them to seek medical attention quickly if signs and symptoms of yellow fever infection occur. Travelers with viraemes may be at risk for establishing local yellow fever transmission cycles in areas where a competent vector is present.

WHO does not recommend any restrictions on travel and trade in Uganda based on information available on this epidemic.

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