The term “African flu” is not a recognized medical or scientific designation for a specific human illness. It is likely a colloquialism or misnomer, potentially describing various diseases in Africa with flu-like symptoms. Understanding these illnesses requires distinguishing between those affecting animals, those affecting humans, and how they differ from common seasonal influenza.
Clarifying the Misnomer
The most probable origin of the term “African flu” stems from African Swine Fever (ASF). This highly contagious viral disease exclusively affects domestic and wild pigs, often leading to nearly 100% mortality in affected animals. It poses no direct public health risk to humans, as the virus cannot bind to or enter human cells, meaning people cannot contract ASF from infected pigs or pork products.
The virus is highly resilient in the environment, capable of surviving on clothing, vehicles, and in various pork products, which facilitates its spread among pig populations across borders. The phrase “African flu” might also be incorrectly applied to actual human illnesses in Africa that initially present with generalized flu-like symptoms, creating confusion about their true nature.
Zoonotic Viruses with Flu-Like Symptoms in Africa
Several zoonotic diseases, illnesses transmitted from animals to humans, occur in Africa and can cause initial symptoms that resemble influenza. Rift Valley Fever (RVF) is one such example, caused by a phlebovirus and primarily affecting livestock like cattle, sheep, and goats. Humans typically contract RVF through contact with infected animal blood or organs, inhaling aerosols during butchering, drinking unpasteurized milk from infected animals, or via mosquito bites. Outbreaks usually coincide with periods of heavy rainfall, which leads to increased mosquito populations.
Initial symptoms of RVF in humans, appearing 2 to 6 days after exposure, often include sudden onset of fever, headache, muscle pain, and joint pain. While most cases are mild and resolve within a week, a small percentage of individuals may develop more severe complications. These can include ocular disease leading to vision loss, meningoencephalitis (inflammation of the brain and its lining), or hemorrhagic fever, which can be fatal in up to 50% of those affected.
Lassa Fever is another example, an acute viral hemorrhagic illness endemic to West African countries such as Nigeria, Sierra Leone, and Liberia. This disease is caused by the Lassa virus, primarily spread to humans through contact with food or household items contaminated by the urine or feces of infected multimammate rats. Person-to-person transmission can occur through exposure to the bodily fluids of an infected individual, particularly in healthcare settings without adequate infection control.
Symptoms, typically manifesting 1 to 3 weeks after exposure, often begin gradually with fever, general weakness, and headache. About 80% of infections are mild or asymptomatic, but severe cases can progress to include sore throat, cough, chest pain, vomiting, and diarrhea. Serious complications in about 20% of patients may involve facial swelling, bleeding from various orifices, neurological issues like hearing loss (often permanent), and multi-organ failure.
Differentiating from Seasonal Influenza
Distinguishing these zoonotic diseases from common seasonal influenza involves examining their causative agents, primary modes of transmission, and typical symptom progression. Seasonal influenza in humans is caused by influenza A or B viruses, which are highly adapted to human hosts and spread through respiratory droplets from person to person. These viruses cause annual epidemics, particularly in temperate climates during late autumn or winter.
In contrast, diseases like Rift Valley Fever and Lassa Fever are caused by viruses from entirely different families (Phlebovirus from Bunyaviridae for RVF, and Lassa virus from Arenaviridae for Lassa Fever). Their transmission is primarily zoonotic, involving contact with infected animals, their products, or vectors like mosquitoes or rodents, rather than efficient person-to-person respiratory spread. While initial symptoms such as fever, headache, and muscle pain can be similar across these illnesses, their progression and potential complications differ significantly.
Seasonal influenza is primarily a respiratory illness, though it can lead to severe complications like pneumonia, especially in high-risk individuals. Diseases such as RVF and Lassa Fever, while starting with flu-like symptoms, can progress to more severe systemic conditions. These include hemorrhagic fever, liver problems, neurological damage, or permanent sensory deficits like hearing loss, which are not characteristic complications of seasonal influenza. The distinct transmission routes and potential for severe, non-respiratory complications help differentiate these African zoonotic diseases from typical human influenza.