Evaluation of molecular and serological assays for improved detection of orthobunyavirus infections in humans and animals in South Africa

Abstract

Over the last few decades, there has been a surge in occurrences of emerging and re-emerging infectious diseases, particularly those caused by viruses. To effectively anticipate and respond to future epidemics, rigorous study and attentive surveillance using numerous indicators are required. The vast majority of new human diseases originated in animals with direct zoonotic or vector-borne transmissions. Arthropod-borne viruses are a significant concern due to increased human-animal interactions, new habitats for vectors, and the expansion of geographic ranges through climate change. The recent development of new orthobunyaviruses underscores this issue, with species nearly doubling from 49 in 2011 to 87 in 2019. Orthobunyaviruses, widespread globally, cause mild to severe infections in humans and animals, raising concerns about public health, zoonotic transmissions, and food security. The goal of this study was to evaluate molecular and serological assays for enhanced orthobunyavirus detection in humans, horses, and other animals presenting with febrile and neurological disease symptoms in South Africa (SA).

In Chapter 2, an assay for detecting Bunyamwera serogroup viruses was developed and optimised, screening human cases of febrile and neurological disease in Gauteng and Mpumalanga. No positive specimens were detected, emphasising the need for further validation and serosurveys to assess exposure in SA. Chapter 3 describes surveillance of orthobunyaviruses in animals, identifying Shamonda virus (SHAV) in an aborted goat foetus, the first detection in SA. Continuous screening is essential to confirm circulation, assess zoonotic potential, and prevent outbreaks. Chapter 4 characterises the SHAV strain, highlighting challenges in obtaining the full genome sequence and emphasising the need for further research on genetic relationships and zoonotic potential. Chapter 5 investigates Shuni virus (SHUV) epidemiology in horses, revealing significant seroprevalence and emphasising the importance of including serological surveillance. The development and validation of a new SHUV IgG ELISA are discussed, highlighting challenges and the need for broader surveillance to identify potential reservoir hosts. This research underscores the importance of continuous and comprehensive surveillance to manage potential outbreaks and enhance public health responses. In conclusion, the findings of this study contribute significantly to understanding orthobunyavirus epidemiology in SA and highlight the need for ongoing surveillance and assay development.