Mmm belongs to the mycoplasmas, a group of cell wall-less bacteria of the class "Mollicutes". It is part of the Mycoplasma mycoides cluster, which consists of five different mycoplasma strains that cause diseases in cattle and goats and which are closely related phenotypically and genotypically(Mycoplasma mycoides subsp. mycoides, Mycoplasma mycoides subsp. capri, Mycoplasma capricolum subsp. capricolum, Mycoplasma capricolum subsp. capripneumoniae, Mycoplasma leachii).
CBPP has been known since the 18th century and spread worldwide in the second half of the 19th century due to livestock trade. It was eradicated in many countries at the beginning of the 20th century through mercy strategies (UK, USA) or the combination of vaccination campaigns and mercy (Australia). Nowadays, the disease is endemic in sub-Saharan Africa, causing great economic damage. Little is known about the current situation in Asia. In Europe, the last case occurred in Portugal in 1999.
Bovine pneumonic disease can be acute, subacute or chronic.
The acute form is dominated by high fever (up to 42 °C) and pronounced respiratory symptoms (cough, chest pain, polypnoea, dyspnoea, nasal discharge). In endemic areas, subacute and chronic forms predominate. These animals show hardly any or unspecific symptoms such as coughing and progressive emaciation up to cachexia. In calves, CBPP is manifested more by arthritis (joint swelling) than by respiratory symptoms.
The clinical expression of the disease is strongly influenced by the virulence of the particular strain and the susceptibility of the host (breed, age, immune status). When a flock is newly infected, mortality can be very high (up to 90%), whereas in endemic areas it is low (<10%).
Pathological changes in the thoracic cavity are considered characteristic. CBPP is characterized by fibrinous bronchopneumonia and pleuritits. In the acute phase, pleural effusions of several liters may form, while in the chronic phase fibrotic adhesions form between the lungs and the chest wall. Changes in the lungs are usually unilateral, preferentially affecting the caudal lobe of the lung. In the early phase of the disease, a typically marbled lung surface is seen due to the encounter of healthy and diseased tissue, separated by thickened interlobular septa. Furthermore, encapsulated necrotic areas, so-called sequestra, are typical. In calves, mainly fibrinous polyarthritides are observed.
CBPP is a highly contagious infectious disease that can spread rapidly. It is mainly transmitted aerogenically. The pathogens have also been detected in saliva, urine, fetal membranes, uterine discharge, and semen. Transplacental transmission is possible. The main source of infection is silent carriers of chronic infection, although live pathogens can persist in encapsulated lung lesions (sequestra) for up to two years and can be reactivated by immunosuppression.
The spread of CBPP occurs mainly through livestock traffic. Countries where CBPP is present are therefore excluded from international livestock trade.