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The disease

Contagious bovine pleuropneumonia (CBPP) is an infectious and highly contagious disease of cattle and water buffaloes, and considered to be amongst the most important infectious diseases. Affected animals have difficulty in breathing due to damage to the lungs, lose condition and a proportion die. All ages of cattle are susceptible, but young cattle develop joint swellings rather than lung infections. Many cattle show no disease signs, despite being infected. Others recover quickly after a transient mild disease, yet they can carry the infection for as long as two years, and may be responsible at a later stage for passing on infection to susceptible cattle.

The cause

The disease is caused by a bacterium called Mycoplasma mycoides subsp. mycoides Small Colony variant (MmmSC), which is difficult to see even with a light microscope. However, growth of the organism can be seen when infectious material is cultured on suitable media in the laboratory.

Animals affected

Cattle of all types (both Bos taurus and Bos indicus) are susceptible; domestic buffaloes are generally more resistant. CBPP has been reported in Asian yaks and in American bison, but never in African buffaloes (Syncerus caffer). Sheep and goats are resistant to the disease.

Geographical distribution

CBPP is widespread in Africa and is recognized to be present in some countries of Asia and Europe.

In Africa, it is found in an area south of the Sahara, from the Tropic of Cancer to the Tropic of Capricorn and from the Atlantic to the Indian Ocean. Endemic infection extends throughout the pastoral herds of much of western, central and eastern Africa, with Angola and northern Namibia in southern Africa. Newly infected areas in the 1990s include much of Uganda, parts of Kenya, the Ituri Region of the Democratic Republic of the Congo, and most of the United Republic of Tanzania, where recently the disease has spread alarmingly. Rwanda (1994), Botswana (1995, now free), Burundi (1997) and Zambia (1997) were recently re-invaded, but Lesotho, Malawi, Mozambique, South Africa, Swaziland and Zimbabwe are currently (2002) free.

In Asia, CBPP has been reported in recent times from Assam in India, Bangladesh and Myanmar. Sporadic outbreaks have been recognized in the Middle East, probably derived from importation of cattle from Africa.

CBPP was eradicated from the United States of America in 1892, Zimbabwe in 1904, South Africa in 1924, Australia in 1972 and China in the 1980s.

After virtual elimination from Europe in the nineteenth century, the disease reappeared in Portugal and Spain in 1951 and 1957, respectively. Outbreaks have been reported in southern France on a few occasions, the latest being in 1984. In Italy, the disease reappeared in 1990 but was eliminated by 1993.

Transmission and spread

CBPP is invariably introduced into a herd by contact with an infected animal; transmission occurs from direct, close, repeated contacts between diseased and healthy animals in shared night accommodation or at water holes, dip tanks, markets, common grazing or gathering places. Indirect transmission from pastures and water or by carriage, for example, on people and feed sacks, is thought not to be important in the transmission of the disease.

The causative agent is present in liquid droplets in breath and urine. Although the CBPP organisms are killed rapidly in hot dry environments, airborne transmission appears possible over distances of up to 200 metres.

Transmission is favoured by close crowding of cattle, and outbreaks are more common and extensive when cattle are housed or have been transported by train or truck or trekked on foot in groups.

Chronically infected and symptomless animals play an important role in the persistence and spread of the disease. In this context, pastoral herds are especially significant since they may contain many chronically infected animals. Fleeing with apparently healthy animals away from a focus of active disease has been known to spread the disease widely.

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