The aim of this study was to identify for the first time single nucleotide polymorphisms (SNPs) associated with Haemonchus contortus resistance in Florida Native sheep, using a targeted sequencing approach. One hundred and fifty-three lambs were evaluated in this study. At the start of the trial, phenotypic records for fecal egg count (FEC), FAMACHA score, body condition score (BCS), and weight were recorded and deworming of sheep with levamisole (18 mg/kg of body weight) was performed. Ten days post-deworming (baseline) and 28 d post-baseline, a full hematogram of each sheep was obtained and FEC, FAMACHA score, BCS, and weight were assessed. Average daily gain was calculated at the end of the trial. Out of 153 animals, 100 sheep were selected for genotyping using a targeted sequencing approach. Targeted sequencing panel included 100 candidate genes for immune response against H. contortus. SNPs were discarded if call rate <95% and minor allele frequency ≤0.05. A mixed model was used to analyze the response variables and included the identity by state matrix to control for population structure. A contemporary group (age, group, and sex) was included as fixed effect. Bonferroni correction was used to control for multiple testing. Eighteen SNPs on chromosomes 1, 2, 3, 4, 6, 7, 11, 15, 18, 20, 24, and 26 were significant for different traits. Our results suggest that loci related to Th17, Treg, and Th2 responses play an important role in the expression of resistant phenotypes. Several genes including ITGA4, MUC15, TLR3, PCDH7, CFI, CXCL10, TNF, CCL26, STAT3, GPX2, IL2RB, and STAT6 were identified as potential markers for resistance to natural H. contortus exposure. This is the first study that evaluates potential genetic markers for H. contortus resistance in Florida Native sheep.

Abstract. 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 receiveroperating 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.

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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).

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