Accelerating Progress Towards the 2030 Neglected Tropical Diseases Targets: How Can Quantitative Modeling Support Programmatic Decisions?

Over the past decade, considerable progress has been made in the control, elimination, and eradication of neglected tropical diseases (NTDs). Despite these advances, most NTD programs have recently experienced important setbacks; for example, NTD interventions were some of the most frequently and severely impacted by service disruptions due to the coronavirus disease 2019 (COVID-19) pandemic. Mathematical modeling can help inform selection of interventions to meet the targets set out in the NTD road map 2021-2030, and such studies should prioritize questions that are relevant for decision-makers, especially those designing, implementing, and evaluating national and subnational programs. In September 2022, the World Health Organization hosted a stakeholder meeting to identify such priority modeling questions across a range of NTDs and to consider how modeling could inform local decision making. Here, we summarize the outputs of the meeting, highlight common themes in the questions being asked, and discuss how quantitative modeling can support programmatic decisions that may accelerate progress towards the 2030 targets.

Defining vitamin D status using multi-metabolite mathematical modelling: A pregnancy perspective

Vitamin D deficiency is linked to adverse pregnancy outcomes such as pre-eclampsia (PET) but remains defined by serum measurement of 25-hydroxyvitamin D3 (25(OH)D3) alone. To identify broader changes in vitamin D metabolism during normal and PET pregnancies we developed a relatively simple but fully parametrised mathematical model of the vitamin D metabolic pathway. The data used for parametrisation were serum vitamin D metabolites analysed for a cross-sectional group of women (n = 88); including normal pregnant women at 1 st (NP1, n = 25) and 3rd trimester (NP3, n = 21) and pregnant women with PET (n = 22), as well as non-pregnant female controls (n = 20). To account for the effects various metabolites have upon each other, data were analysed using an ordinary differential equation model of the vitamin D reaction network. Information obtained from the model was then also applied to serum vitamin D metabolome data (n = 50) obtained from a 2nd trimester pregnancy cohort, of which 25 prospectively developed PET. Statistical analysis of the data alone showed no significant difference between NP3 and PET for serum 25(OH)D3 and 24,25(OH)₂D3 concentrations. Conversely, a statistical analysis informed by the reaction network model revealed that a better indicator of PET is the ratios of vitamin D metabolites in late pregnancy. Assessing the potential predicative value, no significant difference between NP3 and PET cases at 15 weeks gestation was found. Mathematical modelling offers a novel strategy for defining the impact of vitamin D metabolism on human health. This is particularly relevant within the context of pregnancy, where major changes in vitamin D metabolism occur across gestation, and dysregulated metabolism is evidenced in women with established PET.

Effect of trimethoprim/sulfamethoxazole on thyroid function in dogs with pyoderma

The effect of trimethoprim/sulfamethoxazole (T/SMX, 30 mg/kg, PO, q 12 h for 6 weeks) on thyroid function was evaluated in 21 dogs with pyoderma and normal baseline serum thyroxine concentrations. The population mean serum thyroxine concentration, but not the population mean serum triiodothyronine concentration, was significantly decreased at the end of treatment. After 6 weeks of treatment, the response in 3 dogs to thyrotropin administration was substantially reduced. Radionuclide thyroid imaging of 2 dogs after T/SMX treatment revealed higher-than-normal thyroid technetium 99m pertechnetate uptake, suggestive of an interference with iodide metabolism. Use of T/SMX may cause hypothyroidism, and inadequate thyroid function may be incorrectly diagnosed in dogs treated with this antimicrobial.

Comparative body compositions of the dog and goat

The weights of certain organs and tissues of dogs and goats were measured and expressed as percentages of the total body weights. Species differences were observed in the contribution of several organs to the body weight. In the goat, a large percentage of the body weight was due to gastrointestinal contents. When calculations were made with the gastrointestinal contents eliminated from the body weight, many of the originally observed differences disappeared. After exclusion of the weight of gastrointestinal contents, only the values for skin, large intestine, and kidneys were significantly different between species. The possible influence of body composition on drug dosage is discussed.