Academic journal article Bulletin of the World Health Organization

Human Health Benefits from Livestock Vaccination for Brucellosis: Case Study

Academic journal article Bulletin of the World Health Organization

Human Health Benefits from Livestock Vaccination for Brucellosis: Case Study

Article excerpt

Introduction

Brucellosis is one of the world's major zoonoses, alongside bovine tuberculosis and rabies (1). Brucella infection is endemic in humans and livestock in Mediterranean countries (2, 3). It is also present in Asia, sub-Saharan Africa, and Latin America (4-6). The importance of brucellosis is not known precisely, but it can have a considerable impact on human and animal health, as well as wide socioeconomic impacts, especially in countries in which rural income relies largely on livestock breeding and dairy products. Human brucellosis is caused by exposure to livestock and livestock products. The most important causative bacteria in decreasing order are: Brucella melitenis (small ruminants), B. abortus (cattle), B. suis (pigs), and B. canis (dogs). Infection can result from direct contact with infected animals and can be transmitted to consumers through raw milk and milk products. Human-to-human transmission of the infection does not occur (7).

In humans, the symptoms of disease are extreme weakness, joint and muscle pain, headache, undulant fever, hepatomegaly, splenomegaly, and night sweats (8). Mortality is reported to be negligible, but the illness can last for several years. In animals, brucellosis mainly affects reproduction and fertility, reduces survival of newborns, and reduces milk yield. Mortality of adult animals is insignificant (9).

Control strategies available to prevent human infection are pasteurization of milk, livestock vaccination, and elimination of infected animals. In Mongolia, livestock rearing and milk production are important branches of the economy, employing approximately 50% of the population. In the 1970s, mass vaccination of livestock successfully reduced the annual incidence in humans to less than one case per 10 000 (J Kolar, personal communication, 1999, J Kolar, personal communication, 2000). After democratic reform, and the shift away from dependence on the former Soviet Union in 1990, human brucellosis reemerged as a major, but preventable, source of illness. A large survey conducted during 1990-95 among herdsmen and other people who work with animals showed that 16% of the examined population were infected (10). Transmission mainly seems to be an occupational hazard. In contrast, in Saudi Arabia, where consumption of raw milk is important, 30% of the people reported as having brucellosis were aged < 15 years (8).

The Mongolian authorities suspect that the high incidence of brucellosis causes significant economic losses. On the basis of recommendations made to WHO (11), a whole-herd vaccination strategy covering 10 years was developed to start in 2000 (12). Very little is known about the economic implications of brucellosis and brucellosis control far human health in any country (13). The particular zoonotic nature of brucellosis needs a multisectoral assessment, including human health, the socioeconomic situation of the concerned population groups, and livestock production.

The main objective of this study was to estimate the cost-effectiveness to human health and the potential net economic benefits of a nationwide mass vaccination programme for livestock over a period of 10 years. In order to present cost-effectiveness and cost-benefit ratios from different perspectives (health sector, agricultural sector, households, and society), a tool was developed that attributed costs and benefits to these different perspectives.

Material and methods

Selection of alternatives

From 1990, Mongolia has practised low-level surveillance, with occasional testing of livestock herds, followed by voluntary slaughter of infected animals. No state compensation is given far slaughtered animals.

Our analysis of the potential benefit of livestock vaccination is based on the vaccination scheme proposed in the Mongolian budget in 2000 far whole-herd vaccination (Appendix A, web version only, available at: http://www. …

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