Despite large-scale reductions in Chagas disease prevalence across Central and South America, Trypanosoma cruzi infection remains a considerable public health problem in the Gran Chaco region where vector-borne transmission persists. In these communities, peridomestic animals are major blood-meal sources for triatomines, and household presence of infected dogs increases T. cruzi transmission risk for humans. To address the pressing need for field-friendly, complementary methods to reduce triatomine infestation and interrupt T. cruzi transmission, this study evaluated the systemic activity of three commercial, oral, single dose insecticides Fluralaner (Bravecto®), Afoxolaner (NexGard®) and Spinosad (Comfortis®) in canine feed-through assays against Triatoma infestans, the principal domestic vector species in the Southern Cone of South America. Twelve healthy, outbred dogs were recruited from the Zoonosis Surveillance and Control Program in Santa Cruz, Bolivia, and randomized to three treatment groups, each containing one control and three treated dogs. Following oral drug administration, colony-reared second and third stage T. infestans instars were offered to feed on dogs for 30 min at 2, 7, 21, 34 and 51 days post-treatment. Eighty-five per cent (768/907) of T. infestans successfully blood-fed during bioassays, with significantly higher proportions of bugs becoming fully-engorged when exposed to Bravecto® treated dogs (P < 0.001) for reasons unknown. Exposure to Bravecto® or NexGard® induced 100% triatomine mortality in fully- or semi-engorged bugs within 5 days of feeding for the entire follow-up period. The lethality effect for Comfortis® was much lower (50–70%) and declined almost entirely after 51 days. Instead Comfortis® treatment resulted in substantial morbidity; of these, 30% fully recovered whereas 53% remained morbid after 120 h, the latter subsequently unable to feed 30 days later. A single oral dose of Fluralaner or Afoxolaner was safe and well tolerated, producing complete triatomine mortality on treated dogs over 7.3 weeks. While both drugs were highly efficacious, more bugs exposed to Fluralaner took complete blood-meals, and experienced rapid knock-down. Coupled with its longer residual activity, Fluralaner represents an ideal insecticide for development into a complementary, operationally-feasible, community-level method of reducing triatomine infestation and potentially controlling T. cruzi transmission, in the Gran Chaco region.

Latin American countries produce more than a quarter of the world’s beef and are a major global supplier of livestock protein. Tick-borne diseases (TBDs) are a major constraint to the livestock industry worldwide, including in Latin America. The aim of this study was to detect and characterise tick-borne pathogens in cattle from Santa Cruz, Bolivia, where no detailed epidemiological data are available. Blood samples were collected from 104 cattle. Apicomplexan parasites were detected by nested PCR amplification of the 18S ribosomal RNA gene (rDNA), and Anaplasmataceae was screened by the PCR amplification of 16S rDNA, followed by characterisation based on the heat shock protein and citrate synthase gene sequences. Babesia infection was observed in nine cattle (one Babesia bovis and eight Babesia bigemina), while Anaplasmataceae infection was detected in thirty-two cattle. A sequencing analysis confirmed the presence of Anaplasma marginale and Anaplasma platys-like. These results provide the first molecular evidence for the four above-mentioned tick-borne pathogens in cattle in Bolivia. This information improves our understanding of the epidemiology of TBDs and will help in formulating appropriate and improved pathogen control strategies.

In Bolivia, beef production is mainly based on two genotypes, Bos taurus (Creole cattle) and B. indicus (zebu), being weight gain the main selection criteria used by farmers. However, meat quality and especially tenderness must be incorporated in the selection process. Meat tenderness is partly determined by the calpain CAPN1)/ calpastatin (CAST) protein system. Thus, the objective of the present work was to determine and (compare the genetic variability of the CAPN1 gene in Creole (CreBo), Brahman (BraBo) and Nellore (NelBo) breeds in Bolivia. DNA was extracted from blood samples from 147 CreBo, 59 BraBo and 93 NelBo, and three polymorphisms were genotyped using ARMS­PCR (CAPN1­316 and CAPN1­4751) and PCR­RFLP (CAPN1­530). Furthermore, CAPN1­316 and CAPN1­4751 SNPs were analyzed with Axiom™ Bos 1 Genotyping Array r3 and the Axiom™ ArBos 1 Genotyping Array. Allele frequencies associated with higher tenderness in CreBo, BraBo and NelBo were 0.22, 0 and 0.09 (CAPN1­316 C; P < 0.001), 0.76, 0.16 and 0.08 (CAPN1­4751 C; P < 0.001), and 0.77, 0.92 and 0.94 (CAPN1­530 G; P < 0.001). Linkage disequilibrium (LD) analysis revealed the presence of two LD blocks. Our results evidence that CreBo has a higher frequency of alleles associated with higher meat tenderness than the cebuine breeds. These markers could be used in breeding programs to improve Bolivian cattle herd meat quality either by selection within Creole breeds or crosses with cebuine cattle

The major histocompatibility complex or MHC (called in the bovine species "bovine leukocyte antigen, BoLA") is composed of a large number of genes involved in the immune response within the same chromosomal region. Many of these genes have extraordinary levels of polymorphism. Furthermore, these loci have been associated with infectious and autoimmune diseases and with productive traits in different mammalian species. It is for this reason that the study of its structure, polymorphism and evolution has been of great interest to biologists, geneticists and veterinarians during the last decades. The objective of this review is to analyze the state of the art on the characterization of the genetic diversity of BoLA loci, with special emphasis on the BoLA-DRB3 gene in American Creole bovine breeds. In this sense, the methodologies used for the genotyping of this gene (serological and molecular) are detailed. In addition, the main results obtained from the study of the genetic diversity of the BoLA-DRB3 gene are described, as well as from the association studies of this locus with infectious diseases in American Creole cattle. Although much progress has been made in understanding the genetic diversity of the BoLA-DRB3 gene, there is still a long way to go.