Molecular diagnosis of Sarcocystis aucheniae by semi-nested polymerase chain reaction in blood from alpacas (Vicugna pacos) in Peru

Abstract

Background: Sarcocystis aucheniae is the causative agent of sarcocystosis in South American camelids, such as alpacas. The disease is generally asymptomatic in its acute phase and is characterized by the presence of macroscopic cysts in skeletal muscles, which limits the commercialization of alpaca meat. Aim: This study aimed to establish the analytical sensitivity and specificity of the semi-nested polymerase chain reaction (PCR) molecular technique for the diagnosis of S. aucheniae in the blood of alpacas from the province of Huancavelica, Peru. Methods: The analytical sensitivity of semi-nested PCR was determined using very low concentrations of genomic DNA extracted from S. aucheniae macrocysts. The semi-nested PCR assay was compared with the results of the molecular test on blood and the necropsy method. For this purpose, genomic DNA was isolated from blood samples from Huancavelica (n = 8) and Cajamarca (n = 7) alpacas. Furthermore, a previous necropsy was conducted on the muscle tissue of these animals. Furthermore, 42 additional blood samples were collected from alpacas in Huancavelica to detect the 18S rRNA gene of S. aucheniae by semi-nested PCR. Macrocyst DNA was used as a positive control, whereas blood from a negative alpaca for the parasite was used as a negative control. Results: The analytical sensitivity of semi-nested PCR had a detection limit of one picogram of DNA, and the specificity of the technique was 80%. Thirty-two percent (n = 16) of Huancavelica alpacas tested positive for the parasite by semi-nested PCR. Conclusions: Semi-nested PCR had both a satisfactory detection limit and a high degree of specificity for the diagnosis of S. aucheniae in alpaca blood