AUTHOR=La Thi Hai Au , McMillan Ian A. , Dahal Prashant , Burger Andrew H. , Belcaid Mahdi , Phelps Darrin M. , Goldstein Samuel M. , Brown Vienna R. , Norris Michael H. 

TITLE=Tracking sero-molecular trends of swine brucellosis in Hawai‘i and the central Pacific

JOURNAL=Frontiers in Public Health

VOLUME=Volume 12 - 2024

YEAR=2024

URL=https://www.frontiersin.org/journals/public-health/articles/10.3389/fpubh.2024.1440933

DOI=10.3389/fpubh.2024.1440933

ISSN=2296-2565

ABSTRACT=Brucellosis is a zoonotic disease of mammals caused by bacterial species of the Brucella genus. The reservoir for disease is typically mammals, with species of Brucella found infecting amphibians, bats, and marine mammals. Brucella spp. can pass directly to humans through contact with infected animals or their products. Brucella spp. can cause chronic debilitating infections in mammals, including humans, and is associated with spontaneous abortions in infected animals, causing reduced fecundity. In Hawaiʻi, terrestrial species that could harbor Brucella spp. include swine, cattle, horses, and axis deer among others. The numerous feral swine in Hawaiʻi are known to carry Brucella suis, with evidence supporting infections in cattle. Brucella suis also poses infection risk to humans, dogs, and potentially horses across the state. In this study, 3274 feral swine serum samples collected from 5 of the 8 main islands over a 15-year span were analyzed for exposure to B. suis, revealing statewide seropositivity rates triple that of feral swine found in the conterminous United States. Smoothed positivity rates were highest on Maui, followed by Oʻahu, and the island of Hawaiʻi. Of the 558 watersheds in the state, 77 were sampled as part of this effort. Island-by-island analysis found high brucellosis positivity levels associated with specific watersheds and agricultural areas. Local spatial autocorrelation identified hot spots on Oʻahu and Hawaiʻi. MLVA analysis of available B. suis from Hawaiʻi found molecular epidemiological connections with B. suis found in French Polynesia and the mainland US while differing from those in Tonga, Western Polynesia. Whole genome SNP analysis confirmed that strains from Hawaiʻi are phylogenetically closest to strains from the United States. MLVA and SNP analysis found B. suis strains from Hawaiʻi fell into the genetic group that contains biovar 1 B. suis. This work identified islands and watersheds of high brucellosis seropositivity in feral swine of Hawaiʻi, highlighting the magnitude of the zoonotic risk. Introduction of strains in recent history is unlikely due to modern animal trade and disease control practices. Genomic analysis of strains in Hawaiʻi and the Pacific area can provide hidden historical and local clues to brucellosis epidemiology in the state.