A model for malaria treatment evaluation in the presence of multiple species

IF 3 3区 医学 Q2 INFECTIOUS DISEASES Epidemics Pub Date : 2023-09-01 DOI:10.1016/j.epidem.2023.100687
C.R. Walker , R.I. Hickson , E. Chang , P. Ngor , S. Sovannaroth , J.A. Simpson , D.J. Price , J.M. McCaw , R.N. Price , J.A. Flegg , A. Devine
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引用次数: 1

Abstract

Plasmodium falciparum and P. vivax are the two most common causes of malaria. While the majority of deaths and severe morbidity are due to P. falciparum, P. vivax poses a greater challenge to eliminating malaria outside of Africa due to its ability to form latent liver stage parasites (hypnozoites), which can cause relapsing episodes within an individual patient. In areas where P. falciparum and P. vivax are co-endemic, individuals can carry parasites of both species simultaneously. These mixed infections complicate dynamics in several ways: treatment of mixed infections will simultaneously affect both species, P. falciparum can mask the detection of P. vivax, and it has been hypothesised that clearing P. falciparum may trigger a relapse of dormant P. vivax. When mixed infections are treated for only blood-stage parasites, patients are at risk of relapse infections due to P. vivax hypnozoites.

We present a stochastic mathematical model that captures interactions between P. falciparum and P. vivax, and incorporates both standard schizonticidal treatment (which targets blood-stage parasites) and radical cure treatment (which additionally targets liver-stage parasites). We apply this model via a hypothetical simulation study to assess the implications of different treatment coverages of radical cure for mixed and P. vivax infections and a “unified radical cure” treatment strategy where P. falciparum, P. vivax, and mixed infections all receive radical cure after screening glucose-6-phosphate dehydrogenase (G6PD) normal. In addition, we investigated the impact of mass drug administration (MDA) of blood-stage treatment. We find that a unified radical cure strategy leads to a substantially lower incidence of malaria cases and deaths overall. MDA with schizonticidal treatment was found to decrease P. falciparum with little effect on P. vivax. We perform a univariate sensitivity analysis to highlight important model parameters.

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在多种物种存在的情况下评估疟疾治疗的模型。
恶性疟原虫和间日疟原虫是疟疾最常见的两种病因。虽然大多数死亡和严重发病率是由恶性疟原虫引起的,但间日疟原虫在非洲以外的地区消灭疟疾面临更大的挑战,因为它能够形成潜伏的肝期寄生虫(hypnozoites),这可能会导致单个患者的复发。在恶性疟原虫和间日疟原虫共同流行的地区,个体可以同时携带这两种寄生虫。这些混合感染在几个方面使动态复杂化:混合感染的治疗将同时影响两个物种,恶性疟原虫可以掩盖间日疟原虫的检测,并且有人假设清除恶性疟原虫可能会引发休眠的间日疟原虫复发。当混合感染仅针对血液期寄生虫进行治疗时,患者有因间日疟原虫而复发感染的风险。我们提出了一个随机数学模型,该模型捕捉了恶性疟原虫和间日疟原虫之间的相互作用,并结合了标准的杀分裂剂治疗(针对血液期寄生虫)和根治性治疗(额外针对肝脏期寄生虫)。我们通过一项假设的模拟研究应用该模型,以评估混合型和间日疟原虫感染的不同根治治疗覆盖范围的影响,以及“统一根治”治疗策略,其中恶性疟原虫、间日疟原虫和混合型感染在筛查葡萄糖-6-磷酸脱氢酶(G6PD)正常后均接受根治。此外,我们还研究了血期治疗中大规模给药(MDA)的影响。我们发现,统一的根治策略可以大大降低疟疾病例的发病率和总的死亡人数。MDA与精神分裂药治疗可降低恶性疟原虫,但对间日疟原虫影响不大。我们进行了单变量敏感性分析,以突出重要的模型参数。
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来源期刊
Epidemics
Epidemics INFECTIOUS DISEASES-
CiteScore
6.00
自引率
7.90%
发文量
92
审稿时长
140 days
期刊介绍: Epidemics publishes papers on infectious disease dynamics in the broadest sense. Its scope covers both within-host dynamics of infectious agents and dynamics at the population level, particularly the interaction between the two. Areas of emphasis include: spread, transmission, persistence, implications and population dynamics of infectious diseases; population and public health as well as policy aspects of control and prevention; dynamics at the individual level; interaction with the environment, ecology and evolution of infectious diseases, as well as population genetics of infectious agents.
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