Seroprevalence for Rift Valley Fever Virus and Associated Risk Factors in Cattle Slaughtered in Major Abattoirs of Federal Capital Territory, Abuja, Nigeria

Rift Valley Fever is a virus that moves between animals and people, carried primarily by mosquitoes. It belongs to a group of diseases known as zoonoses, which jump from the animal kingdom into human populations. While the virus can cause severe illness and death in livestock like cattle, sheep, and goats, it also poses a direct threat to humans who come into close contact with infected animals. The virus spreads most efficiently when mosquitoes bite an infected animal and then bite a person, but it can also transmit directly through the blood or tissues of a sick animal. This dual pathway makes places where animals are processed for food, such as slaughterhouses, critical zones for monitoring. If the virus circulates quietly among herds without being noticed, it can suddenly surge into a larger outbreak, especially when weather conditions favor the mosquitoes that carry it. Understanding where the virus is hiding and how people interact with it is essential for stopping the next wave of infection before it starts.

In the Federal Capital Territory of Nigeria, researchers set out to map the presence of this virus in the cattle destined for local markets. They focused their investigation on three major slaughterhouses in Abuja, the nation's capital, where thousands of animals pass through each year. The team collected blood samples from 182 cattle that were at least six months old, testing each sample for signs that the animal's immune system had ever fought off the Rift Valley Fever virus. Alongside the biological testing, the researchers spoke with 144 people working in and around these facilities, including butchers, meat vendors, and animal health officials. They asked these workers about their daily habits, their knowledge of the disease, and their exposure to mosquitoes and animal blood. The goal was to see not only if the virus was present in the cattle but also to understand the human behaviors that might allow it to spread from animals to people.

The biological tests revealed that the virus is indeed circulating in the area, though at a low level. Out of the 182 cattle tested, only two were found to have antibodies against the virus, representing a seroprevalence of just 1.1 percent. These two positive cases were located in two different slaughterhouses, the Dei-Dei and Karu abattoirs, while the third facility, Gwagwalada, showed no signs of infection in the animals sampled. The researchers found no significant difference in infection rates between male and female cattle, nor did they find a higher rate in younger animals compared to older ones. The two positive animals were both adults, suggesting that the virus may have been present in the herd for some time, allowing the animals to develop immunity. This low but detectable rate confirms that the virus is not a distant threat but a persistent presence in the local livestock population.

While the virus was found in only a few animals, the human side of the study painted a more concerning picture regarding safety and awareness. When the researchers asked the workers if they knew about Rift Valley Fever, fewer than one-third said they had heard of it. Even fewer understood that the disease could jump from animals to humans. This lack of knowledge was paired with risky behaviors that could easily facilitate transmission. More than half of the workers admitted to eating inside the slaughterhouses while they worked, and a significant portion consumed raw meat or unpasteurized milk. Perhaps most critically, the vast majority of workers reported having frequent contact with the blood of slaughtered animals, often without wearing gloves or other protective gear. Many of these workers also reported being bitten by mosquitoes multiple times a day, a common occurrence in the region that increases the risk of vector-borne transmission.

The study also looked at the environmental conditions that might drive the virus's spread. The researchers found strong statistical links between the risk of infection and specific weather patterns and farming methods. High humidity, heavy rainfall, and high temperatures were all associated with a greater likelihood of the virus being present. These conditions are known to create ideal breeding grounds for mosquitoes, which are the primary carriers of the virus. Additionally, the type of farming system played a role; cattle raised in extensive systems, where they roam over large areas to graze, faced a higher risk of exposure compared to those in more confined settings. This is because the roaming animals have more contact with the mosquitoes that thrive in these open, humid environments. The data suggests that the combination of wet weather, high mosquito numbers, and open grazing creates a perfect storm for the virus to move between animals and potentially into people.

The findings highlight a gap between the biological reality of the virus and the preparedness of the people working with it. The presence of the virus in just over one percent of the cattle is a warning sign that the disease is circulating silently. However, the low level of awareness among slaughterhouse workers and their tendency to engage in unsafe practices, such as eating in work areas or handling blood without protection, creates a dangerous environment for a potential outbreak. The researchers conclude that stopping the spread of Rift Valley Fever requires more than just watching the animals; it demands a change in how people work and think about the disease. Regular testing of livestock, better hygiene in slaughterhouses, and education for workers are necessary steps to protect public health. Without these measures, the quiet circulation of the virus could easily turn into a visible and dangerous epidemic.