Control Interventions for New, Rare and Neglected Infectious Diseases

Monday, June 14 at 5:45pm (PDT)
Tuesday, June 15 at 01:45am (BST)
Tuesday, June 15 09:45am (KST)

SMB2021 SMB2021 Follow Monday (Tuesday) during the "MS03" time block.
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Stacey Smith? (The University of Ottawa, Canada) & Aurelio A. de los Reyes V (University of the Philippines Diliman)


The spread of diseases is dependent on several aspects, including the infectious source or agent, susceptible reservoirs and modes of transmission. These factors influence model development describing the disease dynamics. Thus, suitable models should be built, calibrated and adapted to a specific infectious diseases. Correspondingly, appropriate interventions should be identified to curb the spread of the disease. This symposium presents infectious disease models for new (COVID-19), rare (ebola) and neglected tropical diseases (rabies and schistosomiasis) and suggests policies to control the disease.

Hyojung Lee

(National Institute of Mathematical Sciences,, South Korea)
" Effects of social distancing on transmission dynamics of COVID19 in Republic of Korea"
The novel coronavirus outbreak has rapidly spread out from Wuhan, Hubei Province, China to other countries since December, 2019. The World Health Organization (WHO) declared the COVID-19 outbreak a global pandemic on March 11, 2020. The Korean government implemented the combined interventions including social distancing, and work-at-home policies. In this research, first, the epidemiological characteristics were analyzed in seven geographical areas in Korea. Second, we constructed a mathematical model to assess the control interventions including the social distancing. Third, the effective reproduction numbers by geographical area were estimated. Finally, we assessed the effect of the control strategies as time-dependent interventions using mathematical model approach on the COVID-19 spread to suggest the most effective intervention.

Stacey Smith?

(The University of Ottawa, Canada)
"Modelling the daily risk of Ebola in the presence and absence of a potential vaccine"
Ebola virus --- one of the deadliest viral diseases, with a mortality rate around 90% --- damages the immune system and organs, with symptoms including episodic fever, chills, malaise and myalgia. The Recombinant Vesicular Stomatitis Virus-based candidate vaccine (rVSV-ZEBOV) has demonstrated clinical efficacy against Ebola in ring-vaccination clinical trials. In order to evaluate the potential effect of this candidate vaccine, we developed risk equations for the daily risk of Ebola infection both currently and after vaccination. The risk equations account for the basic transmission probability of Ebola and the lowered risk due to various protection protocols: vaccination, hazmat suits, reduced contact with the infected living and dead bodies. Parameter space was sampled using Latin Hypercube Sampling, a statistical method for generating a near-random sample of parameter values. We found that at a high transmission rate of Ebola (i.e., if the transmission rate is greater than 90%), a large fraction of the population must be vaccinated ($>$80%) to achieve a 50% decrease in the daily risk of infection. If a vaccine is introduced, it must have at least 50% efficacy, and almost everyone in the affected areas must receive it to effectively control outbreaks of Ebola. These results indicate that a low-efficacy Ebola vaccine runs the risk of having vaccinated people be overconfident in a weak vaccine and hence the possibility that the vaccine could make the situation worse, unless the population can be sufficiently educated about the necessity for high vaccine uptake.

May Anne Mata

(University of the Philippines Mindanao, Philippines)
"Models of rabies incidence in Davao City, Philippines and their implications for policy makers"
Rabies is a fatal zoonotic disease and remains to be a priority health concern in the Philippines. The call to eradicate rabies in the Philippines by 2023 led Davao City public health officials to intensify the rabies control interventions. Despite the efforts done to mitigate the disease, rabies cases in dogs remain endemic. In this talk, I will present the status of canine rabies in Davao City as well as the modelling approaches we used to determine the associated factors affecting rabies incidence, explain the mechanisms behind the trend in monthly reported rabies cases, and to evaluate the impact of government-initiated interventions, climate variables, and dog information, which are known as potential disease drivers. Our results revealed that from model estimates, rabies in the city is not epidemic and in order to control the disease, the target vaccination coverage must be consistently met, and that dog population must be regulated. We recommend that the local government unit should consider our findings when conducting strategic planning sessions for achieving a rabies-free Davao City.

Victoria May Mendoza

(University of the Philippines Diliman, Philippines)
"A mathematical model and optimal control of Schistosomiasis in Agusan del Sur, Philippines"
Schistosomiasis is a neglected tropical disease and remains endemic in the Philippines, covering 28 provinces in 12 regions. Schistosomiasis in the Philippines is caused by textit{Schistosoma japonicum}, a zoonotic parasite which infects other mammalian hosts aside from humans. In this work, we develop a mathematical model to study the transmission dynamics of schistosomiasis in Agusan del Sur, Philippines and investigate strategies to control and possibly eliminate the disease. We consider humans and carabaos as definitive hosts, and snails as intermediate hosts. Using the available schistosomiasis data from the Philippine Department of Health, we estimate the transmission probability and contact rate between snails and humans, and infectivities from humans and carabaos to snails. Implementation of multiple control strategies highlight the significance of an integrated approach in mitigating the disease. Improved surveillance and monitoring of cases, and the importance of accurate and updated data are strongly emphasized.

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