Improved serodiagnosis of Trypanosoma vivax infections in cattle reveals high infection rates in the livestock regions of Argentina

TL;DR

A new, more accurate test for detecting T. vivax in cattle was developed, revealing high infection rates in Argentina and highlighting the need for better disease surveillance.

Contribution

The development of a novel TvISG-based ELISA with improved sensitivity and specificity for T. vivax detection in cattle.

Findings

The TvISG-based ELISA achieved 89.6% sensitivity and 93.8% specificity in detecting T. vivax antibodies.

Seroprevalence in Argentina's cattle was 53%, with regional variation from 21% to 69%.

This study reports the first seroprevalence data for T. vivax in Argentina, indicating widespread endemicity.

Abstract

Bovine trypanosomosis, caused by Trypanosoma vivax, currently affects cattle and has a significant economic impact in sub-Saharan Africa and South America. The development of new diagnostic antigens is essential to improve and refine existing methods. Our study evaluated the efficacy of two recombinant antigens in detecting specific antibodies in cattle. These antigens are derivatives of an invariant surface glycoprotein (ISG) from T. vivax. A fraction of a previously described antigen (TvY486_0045500), designated TvISGAf, from an African strain was evaluated, and a new ISG antigen from an American isolate, TvISGAm, was identified. The two antigens were expressed as fusion proteins in Escherichia coli: TvISGAf was fused to the MBP-His-tag, and TvISGAm was obtained as a His-tag fused protein. An ELISA evaluation was conducted using these antigens on 149 positive and 63 negative bovine samples. The diagnostic performance was enhanced by the use of a combination of both antigens (referred to as TvISG-based ELISA), achieving a sensitivity of 89.6% and specificity of 93.8%. Following the validation of the TvISG-based ELISA, the seroprevalence of T. vivax infection in 892 field samples from cattle in the central region of Argentina was determined. The mean seroprevalence of T. vivax was 53%, with variation ranging from 21% to 69% among the six departments studied. These results support the use of the TvISG ELISA as a valuable serological tool for the detection and monitoring of T. vivax infection in cattle. Furthermore, we report for the first time the seroprevalence of T. vivax in Argentina, which highlights the widespread endemic nature of the disease in the region. In order to effectively manage the increasing spread of T. vivax in the vast livestock production areas of South America, it is essential to implement consistent surveillance programs and to adopt preventive strategies.

Bovine trypanosomosis is a disease that threatens cattle health and agriculture in South America and Africa. It is mainly caused by the parasite Trypanosoma vivax. Diagnosis of this infection has been challenging, hampering efforts to monitor and control outbreaks. In this study, we developed a more accurate and sensitive test for detecting T. vivax in cattle. Using recombinant proteins tailored to parasite strains in the Americas, this new test can identify infection rates and patterns within cattle herds and regions. By analyzing over 800 cattle blood samples from Argentina ranchlands, we discovered over 50% seropositivity, indicating a far higher prevalence than previously recognized. These results highlight the urgent need for surveillance and preventive strategies, although diagnostic tools provide a means for tracking regional spread. By enhancing the diagnosis of this livestock disease, this study lays the foundation for protecting cattle health and associated livelihoods across at-risk communities in the developing world. This study exemplifies how molecular innovations can address veterinary challenges and promote food security within resource-constrained farming systems.

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