Hidden epidemics in Africa and power of serosurveillance

Serosurveys have improved our understanding of infectious diseases in Africa. They reveal the true burden of pathogens beyond reported outbreaks.

These studies uncover silent epidemics and provide insights into known pathogens. For example, they show widespread dengue exposure among children and unexpected Marburg virus seroprevalence.

Dr. Anthony Afum-Adjei Awuah leads these efforts. He uses seroprevalence studies to enhance pandemic preparedness.

In early 2021, a research team in Ghana began a public health study. Their goal was to collect blood samples from healthy individuals across the country. They aimed to test for COVID-19 antibodies.

The results were significant. In Tamale, 84.7% had been exposed to SARS-CoV-2. In Kumasi, it was 43.9%, and in Accra, 53.3%. These findings contradicted global assumptions about COVID-19 transmission in Africa and influenced Ghana’s national policy.

Dr. Awuah emphasizes the importance of seroprevalence surveys for pandemic preparedness. “They provide insight into past exposures,” he says, “and support traditional surveillance systems.”

Seroprevalence studies began in the early 20th century with antibody screening from blood samples. These antibodies indicate prior infections, even if undiagnosed.

During World War II, scientists tracked diseases like typhus and malaria using these methods. In the 1980s, they helped understand HIV spread globally.

Today, seroprevalence studies map disease exposures and monitor vaccine coverage. They aim to identify hidden outbreaks and prevent future pandemics.

The work in Ghana was just the start for researchers. They realized that serosurveys could reveal exposures beyond COVID-19.

Under the SERODEN study, blood samples from Ghana showed widespread dengue exposure among children. In Tamale, 36% of children had been exposed by age nine compared to lower rates in Kumasi (5%) and Accra (18%).

“This indicates an increased risk of dengue infection among children,” Dr. Awuah notes. “This knowledge helps us plan public health interventions.”

The SeroMARV study focused on tracking exposure to the Marburg virus, which causes severe hemorrhagic fever.

In July 2022, Ghana faced its first Marburg outbreak with three confirmed cases—two fatal—highlighting the need for proactive surveillance.

Dr. John Amuasi led this effort alongside the Ghana Health Service during the outbreak response. He noted that their inquiries suggested a larger issue than initially thought.

“By deploying well-designed serosurveys,” he explains, “we can better understand what happened.” This knowledge will help prepare Ghana for future outbreaks.

Initial findings indicated some individuals had been exposed to Marburg without showing symptoms typical of the disease.

“Serological assays are not perfect,” Dr. Awuah states, emphasizing the need for better diagnostic tools for these surveys.

Researchers estimated Marburg virus seroprevalence at around 0.6% in Ghana but found cross-reactivity could distort results as well.

“This suggests broader Marburg exposure than we think,” Dr. Awuah says, stressing that improved diagnostics are essential.

Seroprevalence studies can identify hidden threats before outbreaks occur by detecting antibodies against various pathogens based on immunology principles.

“Our work aims to identify transmission hotspots that conventional systems may miss,” Dr.Afum-Adjei Awuah explains further.

Researchers plan to expand activities through the SeroMarv Africa Plus Study across other African countries soon.

This study will assess past pathogen exposures and examine genetic susceptibility roles as well.

Dr.Afum-Adjei Awuah believes Africa must lead its disease surveillance efforts: "To prevent future pandemics," he asserts," we need proactive strategies." Seroprevalence studies offer this opportunity.