Mycoplasma mycoides is a prokaryotic organism recognized primarily as the causative agent of Contagious Bovine Pleuropneumonia (CBPP). CBPP is a highly contagious respiratory illness that affects cattle and water buffalo globally. It is considered one of the most economically devastating livestock diseases, especially in regions where cattle play a significant role in agricultural economies. The organism and the disease it causes remain a major focus for veterinary science and international animal health organizations.
Biological Profile and Unique Features
Mycoplasma mycoides belongs to the class Mollicutes, distinguished from typical bacteria by their simple structure and the complete absence of a rigid cell wall. This structural lack makes the cells pleomorphic, meaning they can change shape easily. It also makes the organism naturally resistant to many common antibiotics, such as penicillin and other beta-lactams, which target cell wall synthesis.
These organisms are among the smallest known self-replicating cells, possessing a minimal genome that reflects a lifestyle heavily reliant on nutrients from its host. The genome contains approximately 985 protein-encoding genes, a very low number for a free-living prokaryote. This genetic reduction means the mycoplasma must scavenge necessary biomolecules, such as amino acids and nucleic acid precursors, directly from its host environment. Pathogenicity is aided by the production of a carbohydrate capsule called galactan and the release of toxic metabolic byproducts like hydrogen peroxide, which damage host cells.
Contagious Bovine Pleuropneumonia (CBPP)
CBPP is a severe disease that targets the lungs and the pleura, the membrane lining the chest cavity, in bovine species. The infection begins in the respiratory tract, leading to a characteristic unilateral fibrinous pleuropneumonia. In the acute form, affected animals display a high fever, lethargy, anorexia, and a persistent, painful cough.
As the disease progresses, severe respiratory distress occurs, characterized by rapid, shallow breathing and often a distinct expiratory grunt. Affected cattle frequently stand with their heads extended, backs arched, and elbows turned outward, a posture adopted to ease the pain of breathing. Inside the chest, the lung tissue becomes consolidated and appears “marbled” due to the accumulation of fluid and fibrin in the interlobular septa, which is a hallmark lesion of CBPP.
Animals that survive the acute phase may develop a chronic form of the disease, characterized by encapsulated necrotic areas in the lungs called sequestra. These lesions can contain live Mycoplasma mycoides for several months, and the bacteria can be released if the sequestrum ruptures. Such chronic carriers may appear healthy, yet they serve as a hidden reservoir, capable of shedding the organism and reintroducing the infection into a herd. The mortality rate in untreated herds can be as high as 50%.
Transmission and Global Distribution
The primary mode of transmission for Mycoplasma mycoides is through direct contact between susceptible and infected animals. The organism spreads via aerosol droplets expelled when an infected animal coughs. This close-range spread means that the movement of infected cattle is the most important factor driving epidemics and the geographical spread of CBPP.
Chronic carrier animals pose a significant challenge to disease control, as they can spread the infection without showing obvious clinical signs. The highly variable incubation period, ranging from three weeks to six months, further complicates efforts to identify and isolate infected stock. While CBPP was successfully eradicated from North America, Australia, and most of Europe, it remains a major veterinary concern. The disease is currently endemic across more than 20 countries in sub-Saharan Africa and is present in some parts of Asia.
Control and Eradication Strategies
Effective management of CBPP relies on rigorous surveillance and swift intervention strategies. The most decisive eradication method, historically successful in developed nations, is the “stamping out” policy, which involves the rapid slaughter of all clinically affected animals and their contacts. This approach is often unfeasible in developing countries due to economic and social constraints related to pastoral economies.
In endemic areas, control efforts are based on extensive vaccination campaigns using live attenuated strains, such as the T1/44 or T1sR vaccines. These vaccines reduce the severity of the disease and limit its spread, but they do not always prevent infection or the development of the carrier state. Strict control of cattle movement and the implementation of quarantine measures are also utilized to limit the introduction of the pathogen into disease-free zones.
Diagnosis is confirmed using serological tests, like the competitive ELISA, to detect antibodies, or by molecular methods, such as Polymerase Chain Reaction (PCR), to identify the organism’s DNA. The use of antibiotics to treat clinically sick animals is generally discouraged by international health organizations. While certain antibiotics can alleviate symptoms, they do not clear the infection and can increase the number of asymptomatic carrier animals, silently perpetuating the disease.