# Seroprevalence and risk factors of small ruminant brucellosis in Jabodetabek, Indonesia

## TL;DR

This study finds a high rate of brucellosis in goats and sheep in Indonesia's Jabodetabek region, with mixed-species farming as a key risk factor.

## Contribution

The study provides the first detailed seroprevalence data on brucellosis in small ruminants in the Jabodetabek region of Indonesia.

## Key findings

- Herd-level seroprevalence of brucellosis was 66.67% in the studied region.
- Mixed-species farms had a significantly higher risk of infection compared to single-species farms.
- Bogor City had the highest animal-level seroprevalence at 11.89%.

## Abstract

Brucellosis, caused by Brucella spp., is a zoonotic disease of major public health and economic significance. In Indonesia, surveillance efforts have predominantly focused on bovine brucellosis, leaving limited data on small ruminants despite their critical role as disease reservoirs. This study aims to estimate the seroprevalence of brucellosis in goats and sheep and to identify potential risk factors associated with its transmission in the Jabodetabek region, Indonesia.

A cross-sectional study was conducted from May 2023 to November 2023, involving 18 herds of goats and sheep across Jakarta, Bogor, Depok, Tangerang, and Bekasi. A total of 665 blood samples (355 from goats and 310 from sheep) and 112 milk samples were collected. The samples were analyzed using the Rose Bengal Test, complement fixation test, and enzyme-linked immunosorbent assay. Descriptive statistics were used to estimate seroprevalence, and a Chi-square test was employed to evaluate risk factors. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to assess associations between risk factors and seropositivity.

The herd-level seroprevalence was 66.67% (12/18), with a mean within-herd seroprevalence of 10.39% (95% CI: 7.21–13.57). The animal-level seroprevalence was 6.17% (41/665), with the highest rates observed in Bogor City (11.89%), followed by Bekasi (8.91%), East Jakarta (8.00%), and Tangerang (4.58%). Depok City had no positive cases in serum tests, though two cases were detected through milk ELISA. Mixed-species farms exhibited a significantly higher risk of infection than single-species farms (OR: 0.30, 95% CI: 0.14–0.66, p < 0.05). No significant difference was observed between goats and sheep (p > 0.05), nor between males and females (p = 0.84).

This study highlights a high seroprevalence of brucellosis in small ruminants within Jabodetabek, with mixed-species farming identified as a major risk factor. The findings underscore the need for enhanced surveillance, control measures, and public health interventions to mitigate disease transmission.