Mpox Antibody Test Validated in Rwanda During Clade 1b Outbreak | Lancet Study

Rwanda has become the first setting to validate an antibody test for mpox, a significant step forward in understanding and managing the evolving outbreak of the infectious disease. The newly developed test, an IgG ELISA assay, offers a crucial tool for assessing past exposure to the virus and refining public health responses. This achievement comes amidst a modern clade 1b outbreak in Rwanda, highlighting the urgent need for accurate diagnostic tools.

Understanding the New Assay

The test, detailed in a recent publication in The Lancet Infectious Diseases, was developed through a collaborative effort between the University of Birmingham, the Rwanda Biomedical Centre (RBC) and the University of Rwanda. It’s designed to detect specific IgG antibodies – proteins produced by the immune system in response to an mpox infection. This ability to identify past exposure is distinct from tests that detect the virus itself, and provides a different, but equally important, layer of information for epidemiologists and clinicians.

The IgG ELISA assay was successfully trialed at the National Reference Laboratory in Kigali, Rwanda, demonstrating its high accuracy and reliability in a real-world setting. The validation process is particularly noteworthy because it occurred during an active outbreak of clade 1b, a variant of the mpox virus, allowing researchers to assess the test’s performance under pressure.

Mpox: A Shifting Landscape

Mpox, formerly known as monkeypox, gained global attention in 2022 with outbreaks reported in multiple countries. Even as initially concentrated among certain populations, the virus has demonstrated the capacity to spread more broadly. The Africa Centers for Disease Control and Prevention (Africa CDC) declared a public health emergency in August 2024, followed shortly by the World Health Organization (WHO), recognizing the escalating nature of the outbreak. The University of Birmingham deployed resources to Rwanda to support the scientific response.

The current outbreak in Rwanda involves clade 1b, a West African strain of the virus that is generally associated with lower mortality rates compared to the Congo Basin clade. However, even with lower mortality, mpox can cause significant morbidity, including painful skin lesions, fever, and swollen lymph nodes. The emergence of clade 1b in Rwanda underscores the importance of ongoing surveillance and the need for tailored diagnostic and control strategies.

What Does Antibody Detection Tell Us?

Detecting mpox antibodies doesn’t necessarily indicate current infection. Instead, it suggests a previous encounter with the virus, either through natural infection or vaccination. This information is valuable for several reasons. It can help estimate the extent of past exposure within a population, informing risk assessments and vaccination campaigns. It can also help differentiate between recent and past infections, aiding in the interpretation of clinical symptoms.

However, it’s important to note that antibody levels can wane over time, and the presence of antibodies doesn’t guarantee complete protection against future infection. The level of protection conferred by antibodies, and for how long, remains an area of ongoing research. The test’s sensitivity – its ability to correctly identify those with antibodies – and specificity – its ability to correctly identify those without – are crucial factors that must be continuously monitored.

The Role of ELISA Assays in Infectious Disease Diagnostics

ELISA, or enzyme-linked immunosorbent assay, is a widely used laboratory technique for detecting and quantifying antibodies, antigens, proteins, and hormones. In the context of mpox, the IgG ELISA assay specifically targets antibodies produced in response to the virus. The assay works by binding a sample to a surface, then using enzymes to detect the presence of the target antibody. ELISA assays are relatively inexpensive and can be performed on a large scale, making them suitable for population-level surveillance.

While ELISA assays are valuable tools, they are not without limitations. False positive results can occur due to cross-reactivity with other antibodies, and false negative results can occur if antibody levels are below the detection threshold. It’s essential to interpret ELISA results in conjunction with other clinical and epidemiological data.

Looking Ahead: Surveillance and Public Health Implications

The validation of this mpox antibody test in Rwanda represents a significant advancement in the global response to the outbreak. It provides a much-needed tool for understanding the extent of past exposure and informing future public health interventions. The test’s success during the Rwandan outbreak demonstrates its potential for use in other settings facing similar challenges.

Ongoing surveillance efforts will be crucial for monitoring the spread of mpox and identifying emerging variants. This includes continued testing for both the virus itself and antibodies, as well as genomic sequencing to track viral evolution. Public health authorities will need to regularly review and update guidance based on the latest scientific evidence. Further research is needed to better understand the long-term immunity conferred by antibodies and the effectiveness of different vaccination strategies. The collaborative spirit demonstrated by the University of Birmingham, the Rwanda Biomedical Centre, and the University of Rwanda will be essential for continued progress in the fight against mpox.