Understanding the incidence and timing of rabies cases in domestic animals and wildlife in south-east Tanzania in the presence of widespread domestic dog vaccination campaigns

The “Zero by 30” strategic plan aims to eliminate human deaths from dog-mediated rabies by 2030, and domestic dog vaccination is a vital component of this strategic plan. In areas where domestic dog vaccination has been implemented, it is important to assess the impact of this intervention. Additionally, understanding temporal and seasonal trends in the incidence of animal rabies cases may assist in optimizing such interventions. Data on the incidence of probable rabies cases in domestic and wild animals were collected between January 2011 and December 2018 in thirteen districts of south-east Tanzania where jackals comprise over 40% of reported rabies cases. Vaccination coverage was estimated over this period, as five domestic dog vaccination campaigns took place in all thirteen districts between 2011 and 2016. Negative binomial generalized linear models were used to explore the impact of domestic dog vaccination on the annual incidence of animal rabies cases, whilst generalized additive models were used to investigate the presence of temporal and/or seasonal trends. Increases in domestic dog vaccination coverage were significantly associated with a decreased incidence of rabies cases in both domestic dogs and jackals. A 35% increase in vaccination coverage was associated with a reduction in the incidence of probable dog rabies cases of between 78.0 and 85.5% (95% confidence intervals ranged from 61.2 to 92.2%) and a reduction in the incidence of probable jackal rabies cases of between 75.3 and 91.2% (95% confidence intervals ranged from 53.0 to 96.1%). A statistically significant common seasonality was identified in the monthly incidence of probable rabies cases in both domestic dogs and jackals with the highest incidence from February to August and lowest incidence from September to January. These results align with evidence supporting the use of domestic dog vaccination as part of control strategies aimed at reducing animal rabies cases in both domestic dogs and jackals in this region. The presence of a common seasonal trend requires further investigation but may have implications for the timing of future vaccination campaigns.

“2030年清零”战略规划（Zero by 30）旨在到2030年消除犬源性狂犬病导致的人类死亡，家犬疫苗接种是该战略规划的核心组成部分。在已实施家犬疫苗接种的地区，评估该干预措施的效果至关重要。此外，掌握家养与野生动物狂犬病病例的时间与季节流行趋势，有助于优化此类干预手段。

本数据集收集了2011年1月至2018年12月期间，坦桑尼亚东南部13个行政区的家养与野生动物疑似狂犬病病例发病数据，该区域胡狼占报告狂犬病病例的40%以上。在此研究周期内，对疫苗接种覆盖率进行了估算：2011年至2016年间，上述13个行政区共开展了五次家犬疫苗接种行动。

研究采用负二项广义线性模型（Negative binomial generalized linear models）探究家犬疫苗接种对动物狂犬病年度发病率的影响，并采用广义加性模型（generalized additive models）分析时间与/或季节流行趋势的存在性。结果显示，家犬疫苗接种覆盖率的提升与家犬和胡狼的狂犬病发病率下降显著相关：接种覆盖率每提升35%，家犬疑似狂犬病病例的发病率将下降78.0%~85.5%（95%置信区间为61.2%~92.2%），胡狼疑似狂犬病病例的发病率将下降75.3%~91.2%（95%置信区间为53.0%~96.1%）。

研究还发现，家犬与胡狼的疑似狂犬病月度发病率存在具有统计学显著性的共同季节流行特征：高发期为2月至8月，低发期为9月至次年1月。本研究结果佐证了将家犬疫苗接种作为防控策略的一部分，可有效降低该区域家犬与胡狼的狂犬病病例数量。尽管共同季节流行特征的成因有待进一步探究，但该特征可为未来疫苗接种行动的时间安排提供参考依据。