Molecular and serological diagnosis of the circulating Trypanosoma evansi in Egyptian livestock with risk factors assessment.

Molecular and serological methods were used to detect Trypanosoma evansi infection in various livestock species across multiple Egyptian governorates, with an analysis of associated risk factors and serum biochemical changes.

Study Overview

• Objective: To determine the prevalence of Trypanosoma evansi infection and assess risk factors in Egyptian livestock using both molecular and serological tests.
• Scope: Sampling was done across nine Egyptian governorates, involving cattle, buffaloes, sheep, goats, donkeys, and horses.
• Additional Focus: Assessment of biochemical changes in serum samples from infected animals.

Sample Collection and Methodology

• A total of 1019 blood samples were collected from January 2020 to September 2021.
• Animal species sampled included:
  • Cattle (n=752)
  • Buffaloes (n=42)
  • Sheep (n=65)
  • Goats (n=60)
  • Donkeys (n=54)
  • Horses (n=46)
• Molecular diagnosis:
  • Polymerase Chain Reaction (PCR) was used to detect the parasite DNA.
  • Sequencing confirmed the infection was exclusively caused by Trypanosoma evansi.
  • The overall PCR prevalence was 3.73% (38/1019 samples positive).
• Serological diagnosis:
  • Indirect ELISA test was applied targeting antibodies against T. evansi.
  • Detected 11 seropositive cases among 519 PCR-negative samples.
  • Overall seroprevalence was calculated as 2.1%.

Risk Factor Analysis

• Geographical Variation:
  • Significant differences in prevalence rates were noted between different governorates.
• Seasonal Variation:
  • T. evansi infection risk was significantly higher in winter (9.83%) than in autumn (1.4%).
  • No infections were recorded in spring or summer, suggesting seasonal influence on transmission.
• Host Factors:
  • No significant differences in infection rates were observed based on animal species, age, or sex.
  • This indicates that environmental or ecological factors may play a larger role than host susceptibility.

Biochemical Serum Analysis

• Parameters assessed included total proteins, albumin, A/G ratio (albumin/globulin), HDL-cholesterol, and globulin levels.
• Results varied by species:
  • Cattle, equines, and goats showed:
    • Non-significant decreases in total proteins, albumin, A/G ratio, and HDL-cholesterol.
    • Non-significant increases in total globulin levels.
  • Sheep showed a different pattern:
    • Significant increases in most tested parameters.
    • Significant decreases only in albumin and A/G ratio.
• These changes indicate possible alterations in immune response and protein metabolism related to infection.

Significance and Recommendations

• This study is the first large-scale epidemiological investigation in Egypt focusing on T. evansi across multiple livestock species and regions.
• It highlights the endemic presence and risk variation with seasons and locations, helping to improve understanding of transmission dynamics.
• The combination of molecular and serological testing enhances diagnostic accuracy since some infected animals were detected only by serology.
• Recommendations:
  • Employ both PCR and ELISA techniques in diagnostic protocols for comprehensive identification of infected animals.
  • Seasonal monitoring and targeted intervention during winter months when infection risk is highest.
  • Further studies on environmental and vector control to mitigate infection spread.