<p>R script for animal study analysis.</p>

Background
India faces the highest burden of human and bovine tuberculosis (TB) globally. Despite this, the association between human TB and livestock exposure remains poorly understood. This exploratory study aimed to evaluate the association between human TB and livestock contact in Wardha district, Maharashtra, India.
Methods
A case-control study was conducted from 01/03/2021 to 31/03/2022. Cases were microbiologically confirmed TB patients in HDSS villages, while controls were asymptomatic individuals from the same villages without TB history. Livestock in these households (HHs) were screened for TB using Interferon-Gamma-Release-Assay (IGRA), Single Cervical-Test (SCT), and Comparative-Cervical-test (CCT). Additionally, community-pooled milk samples were cultured for Mycobacterium tuberculosis complex. Fisher’s exact test was used to calculate crude odds ratios and logistic regression for adjusted odds ratios (AOR) with 95% confidence intervals (CI). A post hoc exploratory analysis to understand the relationship between effect size and sample size requirements was done.
Results
The study included 52 cases and 205 controls, with a median age of 36.5 years (56% men) and 38.5 years (74% men), respectively. Analysis revealed that ownership of livestock and direct contact with cattle did not significantly alter TB risk in humans. Contact with goats showed a marginal association with human TB (AOR: 3.0; 95% CI: 1.0–9.2; p = 0.05). Of 290 livestock screened for TB, none tested positive by confirmatory tests (CCT/IGRA). While 10.2% of cattle showed reactivity to the SIT, this likely represents cross-reactivity with environmental mycobacteria. All bulk milk samples (n = 201) tested negative for MTBC. Post-hoc power analysis revealed that the study had limited statistical power (41%) to detect the observed association with goat contact.
Conclusion
This study found no evidence of bovine TB in livestock or milk samples. While contact with goats showed a marginal association requiring further investigation, livestock ownership and raw milk consumption did not show strong associations with human TB. The absence of confirmed TB in animals suggests zoonotic transmission is not a significant contributor to human TB in this setting. The results highlight the need for larger, regionally diverse studies to better understand livestock-associated TB risk factors in India.

背景
印度是全球人类与牛结核病（Tuberculosis, TB）负担最重的国家。尽管如此，人类结核病与家畜暴露之间的关联仍未得到充分阐明。本探索性研究旨在评估印度马哈拉施特拉邦沃德哈地区人类结核病与家畜接触的关联。
方法
本研究为病例对照研究，实施周期为2021年3月1日至2022年3月31日。病例为HDSS村庄内经微生物学确认的结核病患者；对照则为来自同一村庄、无结核病病史的无症状个体。采用干扰素γ释放试验（Interferon-Gamma-Release-Assay, IGRA）、单颈试验（Single Cervical-Test, SCT）及比较颈试验（Comparative-Cervical-test, CCT）对各家庭户（HHs）中的家畜开展结核病筛查。此外，对社区混合牛奶样本进行结核分枝杆菌复合群（Mycobacterium tuberculosis complex, MTBC）培养检测。采用费希尔精确检验计算粗优势比，采用logistic回归计算校正后优势比（adjusted odds ratios, AOR）及95%置信区间（confidence intervals, CI）。同时开展事后探索性分析，以明确效应量与样本量需求之间的关联。
结果
本研究共纳入52例病例与205例对照，病例组与对照组的中位年龄分别为36.5岁（男性占比56%）与38.5岁（男性占比74%）。分析结果显示，家畜饲养及与牛直接接触并未显著改变人类结核病的发病风险。与山羊的接触与人类结核病存在边际关联（校正后优势比：3.0；95%置信区间：1.0~9.2；p=0.05）。在290头接受结核病筛查的家畜中，经确认试验（CCT/IGRA）检测未发现阳性样本。尽管10.2%的牛对SCT检测呈反应性，但该结果大概率为与环境分枝杆菌的交叉反应所致。所有201份批量牛奶样本的MTBC检测结果均为阴性。事后统计效力分析显示，本研究的统计效力有限（41%），难以有效检测到与山羊接触相关的观测关联。
结论
本研究未在家畜或牛奶样本中检出牛结核病的相关证据。尽管与山羊的接触存在边际关联，需进一步开展研究验证，但家畜饲养及生乳消费与人类结核病并未呈现显著关联。未在动物体内检出确诊结核病的结果提示，在本研究场景中，人畜共患传播并非人类结核病的重要传播来源。本研究结果凸显了开展更大规模、区域多样化研究的必要性，以更好地明确印度地区与家畜相关的结核病危险因素。