Retrospective Screening of Cattle Serum for Leptospirosis in the Morobe Province of Papua New Guinea

Abstract

Leptospirosis is a significant bacterial zoonosis affecting both animals and humans across tropical regions, including Papua New Guinea (PNG). In cattle, this disease can cause abortion, decreased milk production, high fever, jaundice, and reddish-brown urine discoloration, resulting in substantial economic losses for livestock producers. This study, part of an ongoing PhD research investigating leptospirosis epidemiology in PNG livestock, retrospectively analyzed 902 cattle serum samples from 19 farms in the Morobe Province using real-time PCR (qPCR). These samples, originally collected in 2017 through a collaborative NAQIA project and stored at -80°C at PNGIMR, were accessed in 2022 for qPCR. Despite previous documentation of Leptospira interorgans serovars Hardjo and Tarassovi in PNG cattle, all samples tested negative for Leptospira spp. This unexpected outcome may potentially reflect prior vaccination practices in the sampled herds, though vaccination records were unavailable. This finding has prompted further investigation of presumed non-vaccinated cattle farms in subsequent chapters of the PhD project to better determine the true prevalence of leptospirosis in PNG. Nevertheless, this investigation provides valuable baseline data on cattle distribution, breed characteristics, and farm management practices in the Morobe Province that will inform the broader PhD research framework on leptospirosis epidemiology in PNG, contributing to improved animal health surveillance strategies and zoonotic disease control measures.