Brucellosis is a neglected zoonotic disease that affects thousands of people across sub-Saharan Africa each year, yet it remains difficult to diagnose accurately in many health centres. The symptoms—fever, fatigue, joint pain, and headaches—are non-specific and overlap with more familiar illnesses such as malaria, typhoid and many others. As a result, patients are often misdiagnosed and treated for the wrong condition, sometimes repeatedly, before brucellosis is even considered. Limited awareness among healthcare workers further complicates diagnosis. Febrile patients may be treated presumptively for malaria without testing, for example, which can lead to patients with brucellosis not being cured resulting in chronic infections which cause a long-term burden.
At peripheral health centres, diagnosis usually relies on simple serological tests that rely on aggulination. They detect antibodies to the Brucella bacteria in the patient’s blood. More accurate tests—such as ELISA, bacterial culture and potentially PCR—are usually only available in referral laboratories. Culture requires biosafety facilities and trained staff, while PCR needs specialised equipment and reliable electricity, both of which are often lacking in rural settings.
In Kenya, the commonly available agglutination assay is the FBAT – the Febrile Brucella Agglutination Test. This test is very cheap, but is notoriously unreliable, often testing positive when patients are in fact not positive. Such a positive test usually leads to un-necessary treatment. The Rose Bengal test (RBT) is another agglutination assay, which, while not perfect, performs much better than the FBAT. It is marginally more expensive.
Our wider team has already worked closely with the Government of Kenya to change the recommended diagnostic test in public sector hospitals from FBAT to the RBT (see https://www.ilri.org/knowledge/stories/brucellosis-misdiagnosis-costing-kenya-new-policy-aims-change). The national policy change process is ongoing.
An enduring challenge is that many – or indeed most – of the diagnostic tests currently used to detect human brucellosis were originally developed as screening tests for use in livestock. Brucellosis in humans represents a spillover from animals (including cattle, sheep, goats, pigs and in some regions dogs), and early control efforts focused on protecting agricultural productivity and trade by testing animals, with tests designed and validated for veterinary surveillance.
Many peripheral health facilities in low-resource settings rely on assays that borrow from developments in veterinary medicine. For a cross-species disease this can be appropriate, and speaks to the One Health approach, but it does raise some concerns relating to test performance. Yet, in the absence of cheap and easily accessible tests designed specifically for humans, continuing to borrow from veterinary medicine for human diagnosis is a pragmatic, cost-effective and appropriate.
The ZAFI project will be collecting samples from febrile patients in peripheral health units in three countries (Kenya, Ethiopia, Uganda). These will be tested with agglutination tests including the RBT and Standard Agglutination Test (SAT) as well as PCR, providing accurate diagnosis for the patients (leading to improved care) but also providing the project and research community with highly valuable comparative data so we can advise on future diagnostic policy.
