The Caribbean animal health network: new tools for harmonization and reinforcement of animal disease surveillance.

The Caribbean Animal Health Network (CaribVET) is a collaboration of veterinary services, diagnostic laboratories, research institutes, universities, and regional/international organizations to improve animal health in the Caribbean. New tools were used by the network to develop regional animal health activities: (1) A steering committee, a coordination unit, and working groups on specific diseases or activities were established. The working group on avian influenza used a collaborative Web site to develop a regionally harmonized avian influenza surveillance protocol and performance indicators. (2) A specific network was implemented on West Nile virus (WNV) to describe the WNV status of the Caribbean countries, to perform a technology transfer of WNV diagnostics, and to establish a surveillance system. (3) The CaribVET Web site (http://www.caribvet.net) encompasses information on surveillance systems, diagnostic laboratories, conferences, bibliography, and diseases of major concern in the region. It is a participatory Web site allowing registered users to add or edit information, pages, or data. An online notification system of sanitary information was set up for Guadeloupe to improve knowledge on animal diseases and facilitate early alert.

Amblyomma variegatum ticks and heartwater on three Caribbean Islands.

Amblyomma variegatum tick infestation, tick infection by Ehrlichia ruminantium (ER), and ER genetic diversity were studied in the Caribbean Islands of Guadeloupe, Marie-Galante, and Antigua between 2003 and 2005. Nested PCR for pCS20 was used to detect ER, while ER strains were characterized by sequencing or by restriction fragment length polymorphism (RFLP) profiles of map-1 PCR products. In 2003 in Guadeloupe, the prevalence of tick-infested herds was 35.6%. In Marie-Galante 79.1% of herds in 2003 and 73.8% in 2005 were infested, while only an average of 2.2% of the herds were infected in Antigua between this same period. In Marie-Galante, 19.1% of ticks were ER positive, and ER-infected ticks were found in 33.3% of the herds. In Antigua only 5.8% of the ticks were ER positive. High ER tick infection rate combined with a very high level of tick infestation highlight the risk of heartwater in Marie-Galante and Guadeloupe more than in Antigua. The three islands still represent a reservoir for tick and heartwater in the Caribbean. Nine different African and Caribbean map-1 ER genotypes were identified. This diversity was observed even in restricted areas, and identical map-1 genotypes were observed on all three islands. This high genetic diversity of ER strains suggests that there was a simultaneous introduction of several strains from African countries into the Caribbean region.

Comparison of water, oils and emulsifiable adjuvant oils as formulating agents for Metarhizium anisopliae for use in control of Boophilus microplus.

Studies were conducted to identify oil-based formulating agents (paraffinic oil, palm oil and emulsifiable adjuvant oils (EAOs)) for Metarhizium anisopliae that were superior to water with simple surfactants using a germination test and a bioassay against Boophilus microplus. Germination of conidia in all formulations, except 10% coconut EAO, produced more than 68% germination at 24 h and nearly 100% at 48 h. Coconut oil (average survival time (AST) = 4.6 +/- 0.28 days) and 10% liquid paraffin EAO (AST = 4.4 +/- 0.15 days) enhanced the pathogenicity of M. anisopliae to B. microplus relative to water (AST = 8.4 +/- 0.42 days). M. anisopliae in 10% liquid paraffin EAO was the most effective formulation having a moderately high germination after 24 h and a low AST as well as a high AST in the control. In the second experiment, germination of conidia in 2% liquid paraffin EAO and 2% Cropspray was higher than in 2% Codacide oil at 24 h, however, all treatments reached 100% germination after 48 h. The ASTs of the EAO based M. anisopliae formulations (Average AST = 6.4 +/- 0.54 days) were similar but lower that the ASTs of the controls (Average AST = 9.6 +/- 0.28 days).

Assessment of fungal isolates for development of a myco-acaricide for cattle tick control.

Entomopathogenic fungal isolates of Arachnid origin were assessed for their ability to produce mortality and inhibit egg hatching in Boophilus microplus with the aim of selecting an isolate for development into a myco-acaricide for control of cattle ticks. The ability of the most promising isolate to target developmental stages of more than one tick species and the optimum concentration of fungal inoculum to be used for future studies were determined. Metarhizium anisopliae was the most pathogenic of the three fungal species tested on B. microplus, producing shorter average survival times (ASTs) for engorged adults (AST = 5.2 +/- 0.1 days) and larvae (AST = 9.3 +/- 0.4 days), and a longer average hatching times (AHT; AHT = 19.8 +/- 0.5 days) in comparison to Simplicillium lamellicola and Paecilomyces farinosus. In comparative studies on two tick species with similar life cycles, M. anisopliae produced a shorter AST in engorged adult B. microplus (AST = 8.8 +/- 0.3 days) than Rhipicephalus sanguineus (AST = 10.3 +/- 0.3 days). M. anisopliae was pathogenic to larvae of B. microplus (AST = 7.7 +/- 0.4 days), however, had no effect on larvae of R. sanguineus (AST = 14.6 +/- 0.3 days) as the AST of this treatment was similar to its untreated control (AST = 14.1 +/- 0.4 days). M. anisopliae lengthened the AHTs in both B. microplus (AHT = 16.4 +/- 0.3 days) and R. sanguineus (AHT = 16.7 +/- 0.3 days) in comparison to the controls. The ASTs of engorged adult B. microplus treated with M. anisopliae shortened as the concentration was increased from 1 x 10(7) to 5 x 10(8) conidia/ mL. A further increase in concentration, 1 x 10(9) conidia/mL (AST = 10.2 +/- 0.4 days) did not shorten or lengthen the AST in comparison to 5 x 10(8) conidia/mL (AST = 9.4 +/- 0.3 days).

Thermal characteristics of Metarhizium anisopliae isolates important for the development of biological pesticides for the control of cattle ticks.

Experiments were conducted to determine if Metarhizium anisopliae isolates which are capable of growth at cattle surface temperatures could produce pathogenicity to Boophilus microplus in laboratory and field studies. The diurnal temperature fluctuation on the surface of cattle was monitored. The temperature tolerance of M. anisopliae isolates (ARSEF3297 and IMI386697) was determined and their pathogenicity to B. microplus compared at a standard bioassay temperature (28 degrees C) and at a temperature similar to the cattle surface (31-35 degrees C). The effect of the two isolates on the B. microplus population on cattle under field conditions was determined. The temperature of the fore udder, rear udder, ribs and neck regions of the mixed Holstein cattle fluctuated between 30 and 35 degrees C, in a similar pattern to the prevailing environmental temperature. However, wider fluctuations were obtained on the ears (28-35 degrees C) and spine (30-41 degrees C). The colony radius of both isolates declined as temperature increased, however, the growth of IMI386697 was five times greater than ARSEF3297 at 34 degrees C. At 28 degrees C, the pathogenicity of both isolates to B. microplus was similar, however, at 31-35 degrees C, IMI386697 was more pathogenic than ARSEF3297. Both isolates reduced the B. microplus population on cattle in comparison to the control formulation. However, IMI386697 (8.5+/-0.64 ticks/animal) produced a greater reduction in tick numbers than ARSEF3297 (19.1+/-0.64 ticks/animal). M. anisopliae was re-isolated from 8.9% of the ticks collected from IMI386697 treated cattle as compared to 2.8% of ticks from ARSEF3297 treated cattle.

The Caribbean Amblyomma Program: some ecologic factors affecting its success.

The Caribbean Amblyomma Program has been operational for 8 years. However, owing to funding availability, some islands did not commence eradication activities until late 1997. During the past 2 years, 6 of the 9 islands (St. Kitts, St. Lucia, Anguilla, Montserrat, Barbados, and Dominica) under the program have attained the status of provisional freedom from the tropical bont tick (TBT). There are several administrative and technical reasons why the attainment of the program goals took longer than originally anticipated. This paper examines some of the ecologic factors that necessitated the prolongation of the treatment period and the recrudescence of TBT infestation in some islands. The introduction and subsequent spread of the cattle egret, Bulbucus ibis, in the 1960s and 1970s was most likely closely associated with the dissemination of the TBT in the region. At the national or island level, variations in land use are believed to have had a major impact on the eradication efforts in the different islands. Two islands, Antigua and Nevis, both opted out of sugar production several decades ago for economic reasons. Unfortunately, however, land from former sugar estates was not developed for other agricultural purposes and it became "unimproved free-grazing" areas for livestock. Thus, in both Antigua and Nevis, large numbers of livestock tend to become feral or free-ranging, making compliance with the mandatory treatment schedules impossible. In contrast, St. Lucia has large tracts of land allocated to banana plantations and St. Kitts to sugar plantations. Thus, feral or free-ranging livestock were rarely a problem in these islands. These differences in land use management are compared and discussed in relation to their perceived profound impact on TBT eradication efforts in the region.

Eradication of the tropical bont tick in the Caribbean: is the Caribbean amblyomma program in a crisis?

The progress and problems in the Caribbean Amblyomma Program (CAP) are reviewed since its inception in 1995. During 1998, there were funding and administrative management problems. USDA resolved the acute funding crisis, and after three years of negotiation, the CAP has now secured an additional euro 1.5 million from the European Community. Changes in administration in 1998 included the withdrawal of IICA from the program, and the transition during the decentralization of administrative and financial management from FAO headquarters to the Regional Office for Latin America and the Caribbean, based in Chile. A general overview of technical progress and one case study, St. Kitts, is presented. One major concern that emerged during 2000 is that the elimination of the small remaining tropical bont tick (TBT) "hot spots" in both St. Kitts and St. Lucia remained elusive. Why is this so? Egrets? Alternative residual hosts? Or is it fatigue in both technical and administrative management functions? Of even greater concern is the finding of two, apparently new, foci in St. Croix (USVI) in the north and St. Vincent in the south. A critical overview of the program has identified one major remaining constraint-an appropriate management support function at both regional and, in some countries, at the national level. A proposal for a revised management strategy, coupled with the identification of a future strategy to succeed the CAP, namely a Caribbean Animal Resources Management (CARM) Program.

Progress towards the eradication of Amblyomma variegatum from the Caribbean.

Progress in the Caribbean Amblyomma Program (CAP) is reviewed since its inception in 1995 when regional eradication activities for Amblyomma variegatum ticks were initiated using Bayticol pour-on. Technical achievements in the various islands were slow initially, and showed a wide diversity in attaining eradication targets. St. Kitts, considered as a model program. eliminated the tropical Bont tick (TBT) from most of the island in less than 3 years. However, the elimination of very low numbers of residual adult TBT that persisted in three 'hot-spots' took another 3 years. A similar problem was faced in St. Lucia, although the approach there was to cull the wild cattle in the last remaining hot-spot. Both islands were certified as 'Provisionally free from TBT' in November 2001. In 2002, Anguilla and Montserrat attained the same status, and Barbados and Dominica also qualify for certification. Certification is based on strict, three-monthly, surveillance criteria: essentially, two successive TBT-free surveillance rounds on a statistically acceptable sample of the livestock population. Within the responsibility of the CAP, three islands remain TBT-infested, Antigua, Nevis, and St. Martin/St. Maarten. Nevis is of concern because it has been operational since late 1995, and appears unable to resolve the problem of treating stray small ruminants. Current funding should be adequate to complete eradication on Nevis and in St. Martin/St. Maarten. The major outstanding challenge is Antigua. In comparison to other islands they have the largest number of livestock, and have much larger populations than originally reported: sheep and goats are 4-5-fold higher, and cattle are 1.35-fold higher. The cost for Bayticol is, therefore, almost double and an additional US dollars 1.5 million is required for that commodity alone.