Bamako, Mali

Expert opinion : Re-emergence of Contagious Bovine Pleuro-Pneumonia (CBPP) in West Africa

CBPP is an insidious lung disease of cattle caused by Mycoplasma mycoides subsp. mycoides biotype Small Colony (MmmSC). The upsurge in the incidence of CBPP in Africa is a finding of livestock farmers and especially veterinary services, but is unfortunately not properly documented.

Experience at field level shows us that in most of the countries of West Africa, the disease is endemic and has been for several decades. Indeed, the situation of outbreaks registered in the countries of the sub-region in recent years shows that with the exception of Guinea Bissau, Gambia and Senegal, CBPP disease remains endemic and sporadic in most of the countries. The recent evolution of the epidemiological situation is illustrated by the reappearance for the first time since 1971 and 1992 of the disease in the Gambia (September 2012) and Senegal (October 2012) respectively. These countries had stopped vaccination several years ago and Senegal was about to declare itself a provisionally CBPP-free country, in view of its eradication, according to the general principles developed by the OIE.

It must be recognized that Senegal as well as the Gambia, although these countries may not have suffered from CBPP for years, are located in the enzootic disease area. Indeed, all their neighbouring countries regularly report outbreaks to the OIE. In such an environment, it is not surprising that these 2 countries became reinfected because, for various reasons, there are many difficulties in maintaining surveillance at the borders, along with the appropriate quarantine measures. These difficulties include the extensive nature of farming systems in general, porous borders and the fact that the same ethnic populations may be living on both sides of the border(s). This proves beyond reasonable doubt that, in Africa, in its current state, control of TADs and particularly CBPP require the development of regional or sub-regional programmes, similar to the approach used against rinderpest through the Global rinderpest eradication programme. However, due to the global economic recession, it would appear that it is more and more difficult to fund such large scale campaigns as experienced during the massive rinderpest vaccination campaigns. Hence, at least national campaigns, jointly organised with neighbouring countries, should be strongly encouraged.

The risk that the disease may reappear in other African countries with CBPP-free status or that it may extend to new territories where the disease is unknown to date, is increasing. Farming-systems in many African countries and in particular in the West African sub-region are very similar and neighbouring countries often share the same cattle herds because terrestrial borders are quite porous and farmers move their cattle to better pastures, without necessarily knowing that they are crossing international boders.

This picture, associated with inadequacies in human resources (veterinarians and farmers), the likelihood of detection and reporting, deficiencies in vaccination programmes, often not benefiting from government support, as well as the shortcomings in CBPP-related data-collection, is indisputably contributing to the emergence or re-emergence of the disease in West African countries.

It is important to underline that in many parts of Africa, socio-cultural and economic realities do not allow for textbook application of sanitary measures (such as livestock movement restrictions, stamping out and consecutive compensation). Hence vaccination remains currently the only effective way to fight CBPP in most of Africa. However, CBPP vaccines currently used in Africa, are based on the attenuated strain T1, which has a moderate effectiveness. The development of a more effective vaccine for the control of the disease in Africa is therefore a genuine need. For this purpose, several initiatives are underway, including the development of adjuvans-based vaccines that have already been assessed by the African Union’s VACNADA project (vaccines for the control of neglected animal diseases in Africa) with promising results.

Despite all the obstacles mentioned above, there is room for optimism because of the fact that CBPP has been eradicated from Australia in the 1960s, from Tanzania during the colonial period and, more recently, from Botswana (1997). This is evidence that the disease can indeed be controlled and even eliminated in Africa. Moreover, in the recent past, many African countries (e.g. Côte d’Ivoire, Guinea, Senegal) managed to considerably reduce the prevalence of CBPP thanks to the use of the bivalent vaccine (rinderpest + CBPP) during the PARC era (Pan African Rinderpest Campaign). Even better, repeated vaccinations using T1/44 in Namibia has led to a significant reduction in the prevalence of the disease which has helped with the zoning of the country between the north (contaminated area) and south (free zone). Similar initiatives are underway in Mali and Niger as part of their five-year programme to fight against priority animal diseases, including CBPP. The objective is to provide their veterinary services with the necessary resources to vaccinate 80% of the cattle population on an annual basis so that these countries can look forward to a comprehensive control of the disease. However, it would be useful to organise these immunisation campaigns jointly with neighbouring countries. At sub-regional level, CBPP control is relatively high on the list of animal health priorities of the West African Economic and Monetary Union (WAEMU).

In the future, it will be necessary to collect evidence to inform policy makers and donors to support investments in the prevention and control of CBPP as a public good. To this end, it is important to improve the epidemiological knowledge of CBPP and its socio-economic impacts. Prevalence studies and epidemiological surveillance of the disease in the field should be undertaken in order to develop an effective regional or sub-regional animal health information, early warning and rapid response system for the disease. To achieve this, the implementation of active and efficient epidemiological surveillance networks, which should encourage farmers to report cases, along with pathological monitoring in slaughterhouses, is of paramount importance to help identify epizootic areas or areas of recurring outbreaks.
However, these activities can only lead to meaningful results if the capacity of veterinary laboratories in the diagnosis of CBPP is improved as well.

Research into better vaccines that can induce a long or permanent immune protection remains a priority and should therefore be pursued.
Also, it becomes increasingly important, in addition to conventional prevention and control methods, to re-think the way African livestock is managed. Concerted and joint efforts between farmers and veterinary authorities should allow for the emergence of new livestock management perspectives. Farming systems, based on sustainable development principles must prevail to tackle rampant demography, which significantly reduces pasture areas and favors the concentration of herds on scarce resources. These consultations should be held in each country, but also between farming stakeholders across West Africa.

Expert opinion

By Mamadou Niang

Dr Mamadou Niang is a veterinary microbiologist (PhD), specialized in the field of the Mycoplasmata. He has many years of experience in aspects of prevention and control strategies against infectious animal diseases in general and contagious bovine pleuropneumonia (CBPP) in particular, acquired through diagnosis, research and teaching activities. He is author of several papers on the pathology, immunology and epidemiology of animal diseases due to Mycoplasmata, amongst which CBPP. Dr. Niang conducted several of technical backstopping missions for international organisations (FAO, GALVmed…) related to the improvement of strategies to fight priority infectious animal diseases in Africa, i.e. through the strengthening of veterinary clinical and laboratory diagnosis capacity for animal diseases including CBPP. He also worked at AU-IBAR (Inter-african Bureau for Animal Resources of the African Union), Nairobi, Kenya as technical advisor to the VACNADA project. He is currently working at the Central Veterinary Laboratory in Bamako (Mali)
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