Satur Dejell Anne M, Lachica Zython Paul T, Roxas Pamela Grace J, Diamante Eliezer O, Rosero El Veena Grace A, Macanan John Raven C, Lagare Arlene P, Eng Noreen J, Sepulveda Maria Corazon B, Oguis Giovanna Fae R, Mata May Anne E
Department of Mathematics, Physics, and Computer Science, University of the Philippines Mindanao, Davao City, Philippines.
Mindanao Center for Disease Watch and Analytics, University of the Philippines Mindanao, Davao City, Philippines.
Acta Med Philipp. 2025 Mar 31;59(4):90-102. doi: 10.47895/amp.v59i4.8875. eCollection 2025.
Rabies continues to be a challenge in Davao City despite the efforts of the city's local government to vaccinate primarily the non-stray dog population. Meanwhile, studies have shown that time-dependent vaccination strategy is considered a prime factor for a cost-effective rabies control strategy. Hence, this study aims to provide information that will determine the optimal vaccination strategy targeted to the stray dog population that minimizes the rabies-infected dog population and vaccination costs using optimal control theory (OCT).
OCT is used to identify the optimal level of key rabies control, i.e., vaccination. Here, OCT was applied to a modified Susceptible-Exposed-Infectious-Vaccinated (SEIV) compartmental model. The study's key parameters were derived from published articles on rabies in Davao City and similar regions, along with the city's rabies reports.
The findings revealed that while rabies remains endemic in the city, it is possible to reduce the number of cases through consistent implementation of vaccination programs to the exposed and susceptible dog populations. Nevertheless, the feasibility of these findings relies to the effective targeting of vaccine coverage for the dog population. From the simulations performed, the exposed dog population (i.e., pre-rabid dogs) was able to reach zero observation when the transmission rate (β) is 0.001 for all values of anti-rabies vaccine coverages for exposed (α) and susceptible () dog populations and β = 0.01 only when α = 0.7 and = 0.7, α = 0.7 and = 0.5, and α = 0.5 and = 0.7. Consequently, the number of infectious dogs will thereby decrease. Moreover, a nonlinear correspondence was also observed in all scenarios between the vaccination rate and the number of rabies-exposed dogs such that the reduction in the incidence of rabies cases becomes apparent only when the vaccination rate is at least 0.9995.
In high rabies transmissibility scenarios, a time-dependent vaccination strategy demonstrated a reduction in the number of rabies-infected dogs. However, this approach involves a trade-off, limiting the period during which monthly vaccinations can be relaxed. Consequently, a robust and timely vaccination program for dogs is crucial to manage high rabies transmission rates. Lastly, the model simulation underscores the importance of initiating monthly vaccinations.
尽管达沃市地方政府努力主要对非流浪狗群体进行疫苗接种，但狂犬病仍是该市面临的一项挑战。同时，研究表明，时间依赖性疫苗接种策略被认为是具有成本效益的狂犬病控制策略的一个主要因素。因此，本研究旨在提供信息，以确定针对流浪狗群体的最佳疫苗接种策略，该策略使用最优控制理论（OCT）将狂犬病感染狗的数量和疫苗接种成本降至最低。
使用最优控制理论来确定狂犬病控制的关键水平，即疫苗接种的最优水平。在此，将最优控制理论应用于一个改进的易感-暴露-感染-接种（SEIV） compartmental模型。该研究的关键参数来自关于达沃市及类似地区狂犬病的已发表文章以及该市的狂犬病报告。
研究结果显示，虽然狂犬病在该市仍然流行，但通过对暴露和易感狗群体持续实施疫苗接种计划，有可能减少病例数量。然而，这些结果的可行性取决于对狗群体疫苗接种覆盖率的有效靶向。从进行的模拟来看，当传播率（β）为0.001时，对于暴露（α）和易感（）狗群体的所有抗狂犬病疫苗覆盖率值，暴露狗群体（即狂犬病前期狗）能够达到零观察值；仅当α = 0.7且 = 0.7、α = 0.7且 = 0.5以及α = 0.5且 = 0.7时，β = 0.01。因此，感染狗的数量将随之减少。此外，在所有情况下还观察到疫苗接种率与狂犬病暴露狗数量之间存在非线性对应关系，即只有当疫苗接种率至少为0.9995时，狂犬病病例发病率的降低才会明显。
在高狂犬病传播率的情况下，时间依赖性疫苗接种策略显示狂犬病感染狗的数量有所减少。然而，这种方法涉及权衡，限制了每月可放宽疫苗接种的时间段。因此，针对狗的强有力且及时的疫苗接种计划对于控制高狂犬病传播率至关重要。最后，模型模拟强调了开始每月疫苗接种的重要性。
