Ehrlichia ruminantium in Amblyomma variegatum and domestic ruminants in the Caribbean.

The highly sensitive nested pCS20 polymerase chain reaction assay for Ehrlichia ruminantium was negative on 506 Amblyomma variegatum from Caribbean islands where clinical heartwater has not been reported, mainly the United States Virgin Islands (18), Dominica (170), Montserrat (5), Nevis (34), St. Kitts (262), and St. Lucia (17). Positive results were obtained with positive controls (Crystal Springs strain) and A. variegatum from countries in Africa where infections are endemic, mainly Tanzania (1/37) and Burkino Faso (2/29). Positive major antigenic protein-1 enzyme-linked immunosorbent assays for E. ruminantium were obtained on convenience samples of sera from apparently healthy cattle, sheep, and goats on Dominica (0/95, 0%; 3/135, 2%; 2/57, 4%), Grenada (0/4, 0%; 1/98, 1%; 1/86, 1%), Montserrat (0/12, 0%; 0/28, 2%; 5/139, 4%), Nevis (0/45, 0%; 0/157, 0%; 0/90, 0%), Puerto Rico (0/422, 0%; 0, 0%), St. Kitts (3/86, 4%; 1/25, 0%; 0/26, 0%), and St. Lucia (0/184, 0%; 0/15, 0%; 0, 0%), respectively. The pCS20 polymerase chain reaction results indicate E. ruminantium is not present on islands where clinical heartwater does not occur. The occasional positive major antigenic protein-1B enzyme-linked immunosorbent assay results appear, then, to be false-positive reactions, and serology appears to be of limited use in testing for E. ruminantium in the Caribbean, as is the case in Africa.

Seroprevalence estimation and management factors associated with high herd seropositivity for Anaplasma marginale in commercial dairy farms of Puerto Rico.

A cross-sectional study was conducted to determine individual cow seroprevalence of Anaplasma marginale in adult lactating dairy cattle of Puerto Rico (PR) and to assess the associations of farm management factors on herd seroprevalence. Antibody activity against A. marginale was determined using the MSP-5 competitive enzyme-linked immunosorbent assay. Serum samples were obtained from 2,414 adult lactating dairy cattle from 76 randomly selected commercial dairy farms. Herd seroprevalence ranged from 3 to 100% with an overall individual cow seroprevalence for A. marginale of 27.4%. Factors associated with high herd seropositivity were pasture grazing as the main feed source (OR = 6.5, 95% CI = 1.2-34), observed monkeys on the premises (OR = 13, 95% CI = 1.2-138), use of 11% permethrin (OR = 17, 95% CI = 2.2-129), farmers who attended an acaricide certification program (OR = 0.18, 95% CI = 0.04-0.74), and lack of a fly control program (OR = 5.6, 95% CI = 1.3-24).

Seroprevalence estimation and management factors associated with high herd seropositivity for Babesia bovis in commercial dairy farms of Puerto Rico.

A cross-sectional study was conducted to determine individual cow seroprevalence of Babesia bovis in adult lactating dairy cattle of Puerto Rico (PR), to assess the associations of farm management factors on herd seroprevalence, and to document the species of ticks infesting cattle within these farms. Antibody activity against B. bovis was determined using an indirect fluorescent antibody test (IFAT). Serum samples were obtained from 2,414 adult lactating dairy cattle from 76 randomly selected commercial dairy farms. Herd seroprevalence ranged from 0 to 51% with an overall individual cow seroprevalence for B. bovis of 26%. Ticks were collected from animals on 7 (9%) of the 76 participating commercial dairy farms. All collected ticks (n = 87) were Rhipicephalus (Boophilus) microplus. Factors associated with high herd seropositivity were dairy farms with calf but not heifer raising facilities (OR = 16, 95% CI = 3.0-86), having more than 4 neighbors with cattle (OR = 17, 95% CI = 1.6-178), same producer owning more than one farm (OR = 7.2, 95% CI = 1.6-32), and use of government services to apply amitraz on cattle (OR = 5.5, 95% CI = 1.5-20).