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E.P. Cunningham

The emergency created by the unprecedented discovery of the New World screwworm (NWS) in the Libyan Arab Jamahiriya in 1988 was responded to by the collective efforts of Libya and the other North African countries at risk, as well as by a consortium of 14 donor countries and six international agencies, with FAO in a coordinating role. The campaign mounted by FAO to eradicate the infestation mobilized the latest technology and expertise. By the end of June 1991 more than 600 million NWS sterile flies, produced by the Mexico-United States Commission for the Eradication of the Screwworms, had been dispersed over 40000 km² of northern Libya. Subsequent releases extended into areas of Tunisia. Confirmed cases of NWS myiasis in Libya have steadily declined, and it is forecast that the eradication programme could be completed well before originally envisaged. However, caution is still necessary. Releases of sterile flies will continue until there is certainty of no survival of the wild population, after which surveillance and quarantine activities will continue for a further season.

Dr Cunningham is Director of the Screwworm Emergency Centre for North Africa (SECNA) and of the Animal Production and Health Division, FAO.

The discovery of the New World screwworm (NWS) in the Libyan Arab Jamahiriya in 1988 created a clear-cut emergency situation. If allowed to become established, it would present an incalculable threat to livestock, wildlife and humans, initially in North Africa, but also throughout Africa and southern Europe. The response to the emergency has been a fine example of what can be done by collective effort. Libya responded vigorously to the immediate threat. Acting on behalf of the countries at risk and a consortium of 14 donor countries and six international agencies, FAO mounted a concerted campaign to eradicate the infestation. That campaign drew on the resources of many nations and many skills and has been conducted in partnership with the Libyan Veterinary Service. It mobilized the latest technology and expertise, and it has created a bond of effective technical collaboration spanning three continents, a wide range of technologies and a very large network of individuals and agencies.

At this stage, it appears that the campaign has achieved more rapid success than had been predicted.

By the end of June 1991, more than 600 million sterile insects had been transported to Libya from Mexico, where they are produced exclusively by the Mexico-United States Commission for the Eradication of the Screwworms. Up to 40 million of these sterile insects have been dispersed every week over 40000 km² of the northern Libyan territory. Since May 1991, the dispersal area has been extended into the neighbouring areas of Tunisia. This added another 2500 km² to the total zone of dispersal, with distribution densities ranging from 500 to 1200 sterile flies per square kilometre.

The incidence of confirmed NWS myiasis cases has declined steadily since the beginning of 1991 (see Figure 1). A similar trend is found in the cases of confirmed fertile flies captured in traps. At the time of writing, the most recent myiasis case had been detected in April 1991, and the most recent fertile fly capture also took place in that month.

NWS cases in Libya, July 1989 to May 1991 - Cas de lucilie bouchère en Libye de juillet 1989 à mai 1991 - Casos de presencia del gusano barrenador del ganado en Libia, de julio de 1989 a mayo de 1991

Surveillance of livestock in Libya continues. Approximately 444000 animals are still being inspected each week. At strategically placed quarantine posts approximately 12000 animals are inspected weekly.

Eradication plans should have no barriers, and in the countries neighbouring Libya that are most immediately at risk, training, technical preparedness and communication aspects of the programme have also been carried out and are kept under review.

Another role in eradication in Libya has been a highly developed information and communication programme. It was essential that the population, and particularly livestock owners, be well informed on the presence and danger of NWS. Information was aimed at the public through television spots, discussions and programmes. The NWS was featured in newspaper articles, and a documentary film was produced for television in collaboration with the Ministry of Agriculture. Wide distribution was given to four booklets in Arabic on animal quarantine and SIT, precautionary measures to be taken, treatment of wounds and protection for human beings.

Research to support the programme in North Africa has been another indispensable component. It is still being carried out at four locations: in Austria at the FAD/IAEA Agricultural Laboratory, in the United Kingdom at the National History Museum and Tsetse Laboratory, in the United States at the USDA Biosciences Research Laboratory in North Dakota and in Australia at the CSIRO Long Pocket Laboratories in Queensland.

The Natural History Museum in London was also designated by FAO as the Reference Laboratory for Screwworm and Animal Myiasis. The Laboratory has been exchanging information on screwworm and myiasis with more than 20 countries in Africa, countries that hitherto have had little data on wound myiasis. Prevention being better than cure, surveillance in Africa has been both intensive and extensive, well beyond the borders of Libya. Countries under surveillance have been divided into two categories: six high risk (front line) countries and 11 second line countries (see Figure 2). Surveillance activities have included the establishment of check points, livestock movement control, animal inspection, sample collections, prophylactic spraying and public information. By mid-1991 no NWS has been detected in these areas.

Areas for screwworm surveillance - Zones de surveillance de la lucilie bouchère - Zonas de vigilancia del gusano barrenador

The SECNA operation naturally is a costly one. The projected costs for transatlantic transportation of the sterile flies (now by charter direct from Mexico to Libya), strict storage requirements, massive surveillance activities, laboratory diagnostic services, flight dispersal operations, trained personnel, the services of the world's top NWS experts, training courses and administration add up to an estimated US$120 million for the period from August 1990 to December 1992. With the present rapid progress, it is reasonably likely that the campaign will be completed for less than half this amount.

If the present success rate continues, it is likely that the eradication programme can be completed in one year instead of the two originally envisaged. However, caution is advised. Sterile fly releases must continue well into the autumn of 1991, to the point of certainty that none of the wild population has survived. Even then, the programme of animal surveillance and quarantine must be maintained for another season at least. The price of success will be high, but will certainly be a small fraction of the cost of failure.

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