Meat lovers in Thika, north east of Nairobi, are worried. In just one week, eight licensed people who load meat for sale into vans were hospitalised with symptoms similar to anthrax.
They were later discharged, but the story is a sobering reminder of what anthrax and other zoonotic diseases – those passed from animals to humans – can do.
Anthrax, caused by a bacterium called Bacillus anthracis, is primarily a disease of herbivores, and is most commonly transmitted to people through contact with infected materials or the consumption of infected meat.
The latest hospitalisations follow other instances of anthrax outbreaks in Kenya. In May 2016, 16 patients were hospitalised after eating meat from a cow that had died of anthrax.
In August 2015, about 300 buffaloes died of anthrax at the Nakuru National Park.
In another case in May 2014, several people died and some were hospitalised after reportedly eating meat from a hippopotamus infected with anthrax.
The concern of anthrax infection to humans in anthrax endemic countries is associated with handling and consumption of infected meat. However, its potential use as a bioterrorism weapon when anthrax spores are deliberately released to the public has earned it international repute.
So, how should Kenya deal with anthrax outbreaks?
Biologically, the anthrax bacterium’s survival strategy is to form highly resistant spores in unfavourable conditions for it to grow. This allows it to live in soils for long periods of time. Animals then get infected when they graze on soils contaminated with anthrax spores.
The spores germinate, multiply and eventually get into the animal’s blood stream, producing toxins that destroy the blood vessels, eventually killing the infected host.
There are three main forms of the disease in humans associated the route of anthrax infection;
- cutaneous form
It’s the most common form of disease associated with introduction of the bacteria when broken skin comes into contact with infected material.
- the gastrointestinal form
It is associated with the consumption of anthrax infected food and water. It’s common in anthrax endemic countries where public awareness about risk of anthrax is low.
- pulmonary form
This is caused by inhaling anthrax spores. It’s common in industries where workers inhale dust laden with anthrax spores. The deliberate release of high volumes of spores as a biological weapon, like the anthrax-laced letters in the US in 2001, make this form of the disease fearful.
The cutaneous and gastrointestinal types are easily preventable through wearing appropriate protective clothing and gloves, especially for persons at occupational risk of exposure, and public health education about risk associated with eating infected meat.
Persistence of anthrax transmission in animals is dependent on three main factors: the survival of spores, the presence of susceptible animals to the disease, and contact between the spores and these animals.
The way forward
Preventing anthrax demands that the cycle of transmission and infection be broken in the most logical, cost effective and practical approach.
Governments in anthrax endemic countries should build efficient surveillance systems that incorporate anthrax detection, confirmation of diagnosis, efficient reporting, data collation and feedback.
Using data on the occurrence of anthrax outbreaks, methods such as ecological niche modelling can be used to identify potential outbreak areas. This method has been used to identify suitable habitats and hot spots for Rift Valley fever disease in Kenya and in Tanzania.
The identification of anthrax hot spots allows for timely interventions such as vaccination of susceptible animals to be done. This leads to prudent use of limited resources available for disease control in anthrax endemic countries.
Public education focusing on proper disposal of anthrax carcasses, decontamination of infected sites to kill the bacteria, and avoidance of consumption of suspected infected meat, is paramount.
To prevent infection in humans, persons at high risk such as farmers, veterinarians, abattoir workers (like those involved in the recent outbreak in Kenya), or people who work in industries that process animal products – such as bones and hides – should wear appropriate protective clothing to minimise exposure.
The good news is that most anthrax strains can be treated by common and readily available antibiotics. Patients who receive treatment early recover, highlighting the need for effective surveillance systems to catch the disease early.
Like most other zoonotic diseases, stopping anthrax requires close collaboration between the human health, animal health and environmental health practitioners like the zoonotic disease unit in Kenya. This One-Health approach offers both an efficient and cost effective strategy to the success of prevention and control of zoonotic diseases.