Emerging zoonoses affect livestock and humans, which calls for closer cooperation between animal and public health. Conceptually ideal, such cooperation is difficult to achieve and causing agents of outbreaks are often confounded. Lacking awareness may be very likely due lacking capacity and limited resources for diagnosis and surveillance of zoonoses, but also owing to the clinical perspective that focuses on the patients and much less on their surroundings. Consequently governments often neglect zoonotic diseases, reflecting separated sectors of both medicines. The present paper explores the underlying concepts of closer cooperation initially coined as “one medicine” and presents examples of its application and future potential emphasising the African context. Zoonoses are certainly the most prominent example of compulsory interaction between human and animal health. The interaction of humans and animals in Africa is inextricably linked and hence needs a thorough rethinking of institutions, legislations, communication and funding of both sectors.

There is a large untapped potential of new institutional and operational models for providing health services jointly to remote populations which is particularly relevant with regard to ongoing health sector reforms and the human resource crisis. Further, there is a potential for innovative, cost-effective approaches to zoonoses control, for which Pan-African networks would be the best justification for setting up a global fund for zoonoses, similar to and/or linked to the Global Fund to fight HIV/AIDS, Tuberculosis and Malaria.

Introduction
Human and veterinary medicine still appear as well separated sectors and entities in most countries. Evidently veterinarians are not allowed by law to treat humans and physicians only rarely treat animals. However, there are many overlapping issues, mostly in the realms of public health and in the control of diseases transmissible between animals and humans (zoonoses). In such cases cooperation between both sectors becomes crucial, e.g. starting from informing each other on the emergence of new diseases and ending in the long term perspectives of integrated control.

The cooperation between two well structured entitites is not very easily achieved as for example revealed in Rift Valley fever outbreaks in humans in Mauritania that where mistakenly identified as Yellow fever. The correct diagnosis only occurred after contacts with the livestock services who observed abortions in livestock due to Rift Valley fever (1). In sub-Saharan Africa, clinicians relate fever mostly to malaria even though an estimated 50-80% of fevers result from other causes (2). In a case study on fever related diseases in Mali, physicians paid attention to potential zoonotic diseases only after veterinarians identified risk factors for the transmission of zoonoses (3). Lacking awareness may be very likely due lacking capacity and limited resources for diagnosis and surveillance of zoonoses. and  -  equally important - also owing to the clinical perspective that focuses on patients and less on their surroundings. Consequently, governments often neglect zoonotic diseases. The aim of the present paper is to explore the underlying concepts of closer cooperation between human and animal health initially coined as “one medicine”  - and to presents examples of its application and future potential emphasising the African context.

From “one medicine” to “one health” a brief historical background
Ancient healers were priests and cared for both humans and animals (4). They gained anatomical and pathological skills from slaughtering sacrificial animals and deciding on their purity for sacrifice (Leviticus 1,3). Human medicine integrated the medieval universities, whereas veterinary medicine remained largely in the hands of equerries until the 18th century  (5). Claude Bourgelat, the founder of the first veterinary school in Lyon (1762) was heavily criticised when he recommended human clinical training for the veterinary curriculum (6). However, in the 19th century, the pioneers of the microbiological revolution and the advent of cellular pathology (e.g. Rudolf Virchow cited in (7)) manifested a strong interest of interlinking human and veterinary medicine as form of comparative medicine based on discovering similar disease causing agents and pathologic patterns in humans and animals. In the 20th century, both sciences specialised to an extent that their association was hardly visible and less often practiced. It was  Calvin Schwabes’ thorough rethinking of the concept of “one medicine” in 1976, that fully recognized the close systemic interaction of humans and animals for nutrition, livelihood and health (4). Today, the earliest forms of healing of humans and animals are still widely practised in traditional pastoral societies. It is thus not surprising that the “one medicine” is actually of African origin. It was  conceived and conceptually consolidated during Calvin Schwabe’s work with Dinka Pastoralists(8) . It basically means that there is no difference of paradigm between human and veterinary medicine. Both sciences share a common body of knowledge in anatomy, physiology, pathology, on the origins of diseases in all species (4). Later, international organizations such as the WHO and the Food and Agriculture Organization (FAO) institutionalized it partly as Veterinary Public Health (VPH). More recently “ecosystem health” has emerged, seeing sustainable development expressed as the mutualism of the health of humans, animals and the ecosystems in which they co-exist (9) and extending the concept of “one health” to that of the whole ecosystem including wildlife (10-12). Conservationists have recognized, what is known as the “Manhatten principles”(13), that the health and sustainable maintenance of wildlife in natural reserves is mutually interdependent with the health of communities and their livestock surrounding them (14). Finally, many of the causing agents with bioterrorist potential are zoonoses and hence require mutual animal and public health vigilance for rapid detection (15). The “one medicine” hence evolves towards a “one health” concept which reflects the contemporary thinking on health and ecosystems and their relevance for global health development (16).

What does “one health” really mean.
While it is accepted that human and animal health should be much more closely interlinked, the operational strategies still require a substantial re-thinking. To fully exploit synergistic benefits between human and animal health, closer cooperation is required at all levels ranging from international organizations, governments, research and technology, health systems and education.

Governments and international organizations
WHO, FAO and OIE (World Organization for Animal Health) are at the focus of discussion. While they cooperate on zoonotic diseases with transboundary importance such as Avian Influenza (AI), their respective roles and responsibilities are still not fully clarified based on pragmatic considerations of most effective approaches of surveillance and control. Achieving this closer cooperation would provide a strong signal to national governments and all institutions concerned. For example, following the recent outbreaks of AI and RVF in East Africa, many governments have created ad hoc task forces between the concerned ministries of agriculture, livestock production and health, also in Ethiopia. Such cooperation between sectors should be formalized and its mode of operation and responsibilities clarified to make it effective not only in response to crises but even much more as tool for risk analysis, prevention and coordinated, integrated control (16). Many other zoonoses like Q-fever(17), Anthrax and rabies (18) are at stake and would rapidly gain the attention required by such cooperations and interlinkages, which should finally  also strengthen links within and between African countries (19).

Research, technology and health systems
In many countries zoonotic diseases are not considered as important simply because the diagnostic capacity to detect them is hardly existent.  For example, bovine tuberculosis in Chad was not considered important until the first tuberculosis laboratory in the country was able to demonstrate it (20). Joint human and animal surveillance and research on zoonoses accelerates time to detection and the identification of reservoirs (15). Under resource constraints diagnostic facilities could easily be shared (21). Governments often consider the control of zoonoses as too expensive, however, combined societal economic assessments show that their control may actually be highly cost-effective if intervention costs are shared between sectors (22;23). Observations of higher vaccination coverage in cattle than in children in nomadic pastoralists in Chad have led to joint livestock and human vaccination campaigns by inter-sectoral cooperation between the expanded programme of immunisation (EPI) and the veterinary services in Chad (24).  Veterinarians are often the only health person in the remote rural areas and would be competent – after some training training -  to sell also a limited set of essential human drugs under conditions when pharmacists and pharmacies are lacking (25). Such cross-sector arrangements are certainly more effective and also more ethical than leaving the rural population at the mercy of illegal drug sellers and drug peddlers. Moreover, novel models of integrated social services exploiting linkages of education-public health-animal health-environment (26) could make private veterinary services profitable where they can hardly make a living in a privatised scheme  today and would therefore significantly contribute to improved rural health service coverage. Veterinarians would also be instrumental in organizing joint animal human vaccination services (25). Accepting these approaches implies rethinking of new institutional and operational models of joint health services provision which is of particular relevance in view of the current human resource crisis in the health sector (27). Community based surveillance of animal diseases as proposed by OIE at the N’Djamena conference in February 2006 (28) could be extended to public health to accelerate detection of new outbreaks. Current academic and technical curricula should be revised to provide medical doctors with more knowledge of ecological relationships of zoonoses and veterinarians with better knowledge on public health and health systems. Concluding, the major challenge in achieving these inter-linkages lies in effectively combining the public health, animal health and ecosystem health approaches under a common umbrella for comprehensive public health action.

Vision for the future
Zoonoses and their control are certainly the most prominent example of the need to combine human and animal health.  The interaction of humans and animals in Africa is much closer and directly visible e.g. by the breakdown of livestock production due to the HIV epidemic (29) or the livelihood consequences of animals diseases (30). Moreover, we should not forget the past disaster of Rinderpest imported to Ethiopia during colonial rule (4). These inextricable linkages show the need for a thorough rethinking of institutions, legislations, communication and funding of both sectors. There is a large untapped potential of new institutional and operational models for providing health services jointly to remote and/or neglected populations which is of highest relevance within the context of ongoing health sector reform programs and the human resource crisis. Limited laboratory capacity and infrastructure can easily be shared between sectors, and needs no further justification as the pathogens dealt with are the same for humans and animals. The populations concerned in rural and urban areas have specific knowledge about diseases in their surrounding which can be better used for community based surveillance, but also to define priorities for action and the translation of evidence into policy,  comparable to the East African REACH consortium with their activities to link research outcomes with political and strategic and decision makers (31). These examples certainly enhance the urgently needed improved communication between sectors and also allow making much better use of  non-Western knowledge of  “integrated” pastoral societies with their own pragmatic solutions for problem-solving  (4).
Concluding, there is a potential for innovative, cost-effective approaches to zoonoses control (23), for which cooperation between the human and animal health sectors should be extended internationally analogous to the concerted approach of rabies control in South America (19). Pan-African networks for zoonoses control would be the best justification for a global fund for zoonoses  similar to and/or linked to the Global Fund to fight HIV/AIDS, Tuberculosis and Malaria.

Acknowledgement
Wellcome Trust and National Centres for Competence in Research North-South (NCCR North-South – mitigating syndromes of global change, Integrated Project 4/Work package 3 “health & wellbeing”) are acknowledged for funding.

Jakob Zinsstag DVM PhD
Prof. Dr. Marcel Tanner

Swiss Tropical Institute, PO Box, 4002 Basel, Switzerland,
Tel. +41 61 284 81 39, Fax: +41 61 284 81 05

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Pictures (click to enlarge)

Left picture: participatory planning in nomadic communities in Chad with Prof. Marcel Tanner and Cheik Kagame.

Right picture: meeting with the nomadic population discussing human and animal health.