ABSTRACT
This study tested the impact of moxidectin at peripartum on nematode fecal egg count (FEC) and clinical parameters on ewes in the high altitude tropical Andes of Colombia. FEC and clinical evaluations were performed on 9 occasions in 43 naturally infected ewes before and during gestation and after lambing. Moxidectin (Mox, 200 µg kg(-1)) was applied at late pregnancy (T 1, n = 15) or 48 hours after parturition (T 2, n = 14). 14 untreated ewes served as controls (C). Suckling lambs (n = 58) remained untreated and underwent four clinical and parasitological evaluations until 8 weeks after birth. Mox efficacy equaled 99.3% (T 1) and 96.9% (T 2). Highest mean FEC value reflecting periparturient nematode egg rise (PPER) was recorded in C ewes at 4-6 weeks after lambing. Significant FEC reductions were found in T 1 (94.8%) and T 2 (96.7%) ewes (p < 0.05). All lambs showed a significant and ewes-group independent increase in FEC before weaning (p < 0.05). Clinical parameters (anemia and diarrhea) showed time- and treatment-related differences (p < 0.05). Monitoring of FEC and clinical parameters linked to gastrointestinal parasite infections allowed demonstrating that postpartum or preweaning are two critical periods to nematode infection for sheep raised under tropical Andes high altitude conditions. Use of Mox as anthelmintic treatment prevented PPER.
ABSTRACT
The prevalence of Toxoplasma gondii in 309 unwanted dogs from Bogotá, Colombia, South America was determined. Antibodies to T. gondii were assayed by the modified agglutination test (MAT) and found in 52 (16.8%) of 309 dogs with titers of 1:20 in 20, 1:40 in six, 1:80 in 17, 1:160 in three, 1:320 in three, 1:1280 or higher in three. Some organs obtained after necropsy of dogs (hearts, tongues and brains, either separately or pooled) were used in bioassays carried out in mice (37 samples, of which 20 were assayed with separate organs and 17 were assayed with pooled organs), cats (pooled organs from six) and pooled organs of two dogs both in mice and cat. Mice receiving dog tissues were examined for T. gondii infection. Feces of cats that received dog tissues were examined for oocyst shedding. In total, T. gondii was isolated from tissues of 20 dogs (16 by bioassays in mice, 3 by bioassay in cats and 1 by bioassay in mice and cat). All infected mice from 7 of 17 isolates bioassayed in this host died of toxoplasmosis during primary infection. Only 10 of the 20 dogs whose tissues were bioassayed separately induced infections in mice. Interestingly, dog organs varied in their capacity to induce T. gondii infection in mice, hearts and tongues producing more positive results than the brain. The 20 T. gondii isolates obtained from seropositive dogs were PCR-RFLP genotyped using polymorphisms at 10 nuclear markers including SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, a new SAG2 and an apicoplast marker Apico. Ten genotypes were revealed. These genotypes are different from the three predominant Types I, II and III lineages that are widely spread in North America and Europe. A new allele denoted u-3 at PK1 locus was identified in three isolates. This result supports previous findings that T. gondii population is highly diverse in Colombia.
