Transboundary pests and diseases are a permanent threat to crop and animal producers. They have major economic implications, both in terms of the private and public costs of an outbreak and in terms of the cost of measures taken at individual, collective and international levels to prevent or to counter infestations.
This review has discussed the economic rationale for public intervention, based on the "public good" nature of many control efforts. The need for public intervention frequently extends to the international level and calls for international and regional cooperation, without which many control efforts cannot be expected to be effective. However, in practice it can be more difficult to determine the appropriate level and type of control, or the proper mix of private and public and national and international action.
One problem is that the paucity of accurate data and information on the costs both of transboundary pest and disease effects and of control efforts makes it difficult to decide on the most cost-effective interventions. It can also be difficult to ensure the necessary collective action, particularly at the international level, as parties and countries involved may have quite different incentives for participating in control efforts. Closely related to this is the question of cost sharing in control action.
Recent years have seen both progress and retreat. The technical ability to control old problems has greatly advanced and improved information exchange has facilitated reaction to the emergence of transboundary pests and diseases. At the same time, however, increased movements of people and goods have facilitated the spread of many pests and diseases, while a number of new forms have appeared - the emergence and spread of BSE in Europe being one example.
These developments strengthen the case for collective action at the regional and international level. Following are some of the challenges faced in the area of transboundary pests and diseases today:
In short, the issue of transboundary plant pests and animal diseases is of growing economic and scientific complexity and consequently warrants priority attention.
1 Other relevant definitions of regulated pests and diseases are as follows: "[A quarantine pest is a] pest of potential economic importance to the area endangered thereby and not yet present there, or present but not widely distributed and being officially controlled" (IPPC. 1999. Glossary of phytosanitary terms. International Standards for Phytosanitary Measures Publication No. 5. Rome, FAO); and "... a disease listed by the Veterinary Administration, and that, as soon as detected or suspected, must be brought to the attention of the Veterinary Authority" (OIE. 1999. International Animal Health Code. Paris).
2 The term "pest" includes all organisms (insects, diseases, etc.) that reduce yield or satisfaction from crops and other plants. In the case of animals, specialists use the term "animal disease" to include parasites and other pests in addition to disease. For simplicity, the term "transboundary pests and diseases" is used in this review.
3 A distinction is made between migratory and quarantine pests. Migratory pests move from one place to another on their own accord, whereas quarantine pests generally require a human or other carrier to move from one place to another (the term "quarantine" derives from the 40 days of isolation imposed in previous ages on foreign sailors arriving in Venetian ports).
4 Dynamic factors affecting risk are discussed in the section, Factors determining the levels of control.
5 These data were compiled from official disease reports submitted to OIE. They may severely underrepresent the actual number of cases, particularly for diseases of non-commercial animals, such as peste des petits ruminants in small ruminants, African swine fever in village pigs and Newcastle disease in poultry in Africa and Asia.
6 D.T. Jamison, J. Frenk and F. Knual. 1998. International collective action on health: objectives, functions and rationale. Lancet, 351(9101): 514-517.
7 The "marginal cost" is the cost imposed by one additional increment of the control effort. The "marginal benefit" is the benefit obtained from an additional increment of control.
8 FAO. 1998. Economic and policy issues in desert locust management: a preliminary analysis. By S.R. Joffe. Technical Series - Desert Locust Field Research Stations No. 27. Rome.
9 FAO. 2000. Socio-economic impacts of freedom from livestock disease and export promotion in developing countries. By A. McLeod and J. Leslie. Livestock Policy Discussion Paper No. 1. Rome.
10 The tsetse fly demonstrates the latter situation in which only areas suitable to the insect hold the threat of sleeping sickness of animals.
11 B. Hardeweg. 2000. A guide to economic evaluation of desert locust management projects. University of Hannover (manuscript.)
12 IFPRI. 1999. Livestock to 2020: the next food revolution. IFPRI Discussion Paper No. 28. Washington, DC.
13 Op. cit., note 9.
14 IFPRI. 1998. Pest management and food production. IFPRI Discussion Paper No. 25. Washington, DC.
15 Op. cit., note 11.
16 Op. cit., note 8.
17 M. Belhaj. 2000. The environmental economics of desert locust: the cases of Morocco and Sudan (unpublished resumé). See www.handels.gu.sc/econ/EEU/rbelhaj.htm.
18 Ibid.
19 Op. cit., note 11.
20 D.E. Wright. 1986. Economic assessment of actual and potential damage to crops caused by the 1984 locust plague in southeastern Australia. Journal of Environmental Management, 23: 293-308.
21 D. Rose, C. Dewhurst and W. Page. 1997. The African armyworm handbook. Nairobi, Desert Locust Control Organization.
22 Op. cit., note 8.
23 C.E. Miller, L. Chang, V. Beal, R. McDowell, K. Ortman and T. LaCovey. 1992. Risk assessment: Mediterranean fruit fly. Washington, DC, APHIS, USDA; A. Joomaye, J. Knight and W. Routhier. 1999. Evaluation of the peach fruit fly problem in Egypt, with recommendations for its control and eradication, including a limited cost-benefit analysis. Report on a mission to Egypt, 11-24 June 1999. Project code: C3-INT/0/069 13 01. Vienna, IAEA; and J.M. Stonehouse, J.D. Mumford and G. Mustafa. 1998. Economic loss to tephritid flies (Diptera: Tephritidae) in Pakistan. Crop Protection, 17(2): 159-164.
24 Joomaye, Knight and Routhier, ibid.
25 Stonehouse, Mumford and Mustafa, op. cit., note 23.
26 USDA. 1995. Economic feasibility of eradicating the carambola fruit fly from South America. Washington, DC.
27 Op. cit., note 14.
28 The Economist. 2000 (23 December).
29 D. Pimentel, L. Lach, and R. Zúñiga and D. Morrison. 1999. Environmental and economic costs associated with non-indigenous species in the United States. Ithaca, New York, USA, Cornell University.
30 Op. cit., note 28.
31 Op. cit. (p.11), note 9.
32 E.N. Tambi, O.W. Maina, A.W. Mukhebi and T.F. Randolph. 1999. Economic impact assessment of rinderpest control in Africa. Revue scientifique et technique Off. int. épiz., 18(2): 458-477.
33 If, for example, a pig population remains stable at an annual offtake rate of 50 percent, over a two-year period a population of 100 pigs will produce 100 pigs for consumption. If 50 pigs die from classical swine fever, in order to re-establish the original population size of 100 pigs, only 12.5 pigs can be slaughtered for consumption at the end of two years, which results in a net difference in production of 87.5 pigs.
34 FAO. 1997. Consultancy report on cost-benefit of different vaccination strategies for the control of classical swine fever. By M.J. Otte. Rome.
35 P.R. Ellis and S.N. Putt. 1981. The epidemiological and economic implications of foot-and-mouth disease vaccination programme in Kenya. Consultancy Report to the Government of Kenya.
36 J. Leslie, J. Barozzi and M.J. Otte. 1977. The economic implications of a change in FMD policy: a case study in Uruguay. In Proceedings of the 8th International Symposium on Epidemiology and Economics, Paris, 8-11 July 1997. Published as a special issue of Épidémiologie et santé animale, 31-32.
37 Op. cit., note 9.
38 Ibid.
39 R.F. Townsend and H.K. Sigwele. 1998. Socio-economic cost-benefit analysis of action and alternatives for the control of contagious bovine pleuropneumonia in Ngamiland, Botswana. Final Report. London, DFID.
40 Op. cit., note 9.
41 Ibid.
42 R. Repetto and S.S. Baliga. 1996. Pesticides and the immune system: the public health risk. Washington, DC, WRI.
43 Op. cit., note 17.
44 M. Fafchamps. 1999. Rural poverty, risk, and development.Centre for the Study of African Economies, Oxford University. Report submitted to FAO.
45 T. Reardon in FAO. 1998. The State of Food and Agriculture 1998, Part 3. Rural non-farm income in developing countries. Rome.
46 WTO. 1998. Annual report, Chapter four, Globalization and Trade. Geneva.
47 L. Glowka and C. de Klemm. 1999. International instruments, processes, organisations and non-indigenous species introductions: Is a protocol to the Convention on Biological Diversity necessary? In O.T. Sandlund, P.J. Schei and Å. Viken, eds. Invasive species and biodiversity management. London, Kluwer Academic.
48 For example, J.D. Mumford, M. Temple, M.M. Quinlan, P. Gladders, J. Blood-Smyth, S. Mourato, Z. Makuch and J. Crabb. 2000. Economic evaluation of MAFF's Plant Health Programme (2 vols). London, Report to the Ministry of Agriculture, Fisheries and Food.
