RESUMO
A prevalence study was conducted to survey tick larvae populations in Puerto Rico (PR), compare the number of infested sites with Rhipicephalus (Boophilus) microplus larvae between the wet and dry season, and assess the associations of ecologic factors on the presence of R. microplus larvae. Ninety-six sites were selected using a GIS-based sampling method. Each site was sampled twice; the first sampling was performed during the dry season (March 4-18, 2007) and the second sampling during the wet season (August 13-26, 2007). Sites were sampled using a tick drag with a 1-m(2) white flannel cloth along a 50-m straight course. Only 2 tick species were identified. In the dry season, 15 sites (0.16, 95 % CI = 0.09-0.24) were identified with R. microplus larvae (n = 606) and 9 sites (0.09, 95 % CI = 0.04-0.17) with Dermacentor (Anocentor) nitens larvae (n = 779), whereas in the wet season 5 sites (0.05, 95 % CI = 0.02-0.12) were identified with R. microplus (n = 94), and 5 sites (0.05 %, 95 % CI = 0.02-0.12) with D. nitens (n = 275). Difference in the number of infested sites with R. microplus was significant (P = 0.031) between the 2 seasons. Factors associated with the presence of R. microplus larvae in PR were wind speed of >4.0 km/h (OR = 0.07, 95 % CI = 0.01-0.63), more than 25 % bushes and shrubs on the site (OR = 11, 95 % CI = 1.6-71), and presence of cattle on the site (OR = 26, 95 % CI = 3.4-188).
Assuntos
Meio Ambiente , Rhipicephalus , Animais , Bovinos , Geografia , Larva , Modelos Logísticos , Densidade Demográfica , Porto Rico , Estações do AnoRESUMO
Bovine anaplasmosis (BA) is a hemoparasitic disease of great importance in cattle within the tropical and subtropical regions of the world. Control programs for BA require accurate diagnostic assays but validation can be challenging because the true disease status of all animals is frequently not known with certainty. The objective of this study was to estimate the accuracy of assays for detection of Anaplasma marginale infection in lactating dairy cattle of Puerto Rico using Bayesian methods without a perfect reference test. There were 2,331 cattle with complete diagnostic results sampled from 79 herds, and the prevalence of BA was estimated as 22% (95% probability interval [PI]: 19-25%). The sensitivity (Se) and specificity (Sp) of a major surface protein 5 competitive enzyme-linked immunosorbent assay (MSP-5 cELISA) were estimated as 99% (95% PI: 96-100%) and 89% (95% PI: 87-92%), respectively. The Se and Sp of a quantitative polymerase chain reaction (qPCR) were 67% (95% PI: 60-74%) and 99% (95% PI: 99-100%). The Se and Sp of a card agglutination test were 34% (95% PI: 29-39%) and 99% (95% PI: 99-100%). Area under the receiver-operating characteristic curve for the MSP-5 cELISA was 0.748 (95% PI: 0.71-0.79). The MSP-5 cELISA appears to be the test of choice for screening cattle for subclinical BA based on the high estimated Se, rapidity of results, relative low cost, and ease of standardization.