YSPH Research & Discoveries February 2025

Genome-wide association studies have been crucial for identifying genetic variants linked to diseases, yet current methods primarily focus on single nucleotide polymorphisms (SNPs) individually. This common practice is prone to errors, missing genetic variations that could contribute to disease (false negatives) on the one hand, and yielding others that cannot be repeated (likely false positives).

A new study reported by Dr. Heping Zhang, PhD, the Susan Dwight Bliss Professor of Biostatistics, and Dr. Yiran Jiang, PhD, a postdoctoral associate at Yale School of Public Health, introduces a more robust and accurate technique that synthesizes the information of SNPs in local regions and reduces both false positive and false negative errors.

The Regional Association Score (RAS) method proposed by Jiang and Zhang quantifies associations between SNPs and disease traits by converting regional SNP data into a time-series format. The RAS method applies a change point detection algorithm that Dr. Zhang originally developed for time series data monitoring of patients with HIV.

Specifically, their simulation studies show that while controlling the false discovery rate, RAS increases detection power by over 20% in complex genetic landscapes, particularly in cases where causal variants are sparse. Additionally, when applied to real genetic data from the Adolescent Brain Cognitive Development (ABCD) study, the method successfully identified regions associated with mental health traits, reinforcing its potential impact on disease research.

This study highlights an innovative step forward in genetic research as a result of the elegant use of statistical methods and theory, offering a more accurate and efficient approach for detecting disease-related genetic variants. The authors anticipate that RAS could significantly enhance genetic studies and precision medicine, paving the way for improved disease prediction and treatment strategies.

Empowering Genome-Wide Association Studies via a Visualizable Test Based on Regional Association Score (PNAS, published online February 25, 2025)

— Janice Hur

A new study from the Yale School of Public Health sheds light on the implications of racism-related stress on the health and well-being of Asian American sexual minority men.

The key findings reveal a noteworthy association between racism-related stress and increased substance use.

The study analyzed data from 62 Asian American sexual minority men, aged 18–34, who participated in the HIV Oral Self-Testing Infographic Experiment (HOTIE). Using the Asian American Racism-related Stress Inventory (AARRSI), researchers found that higher levels of racism-related stress were linked to greater use of cigarettes and e-cigarettes. While alcohol consumption did not show a direct correlation with racism-related stress, those who drank more than four days a week had higher stress scores than those who drank less frequently. The study reported no significant correlation between racism-related stress and general or oral health.

The study also explored attitudes toward pre-exposure prophylaxis (PrEP), an HIV prevention strategy. Although 75.8% of participants were familiar with PrEP and 90.3% approved of its use, only 6.5% were currently taking it. This gap suggests that stigma and other barriers may hinder PrEP uptake, even among those who are aware of its benefits.

The findings underscore the compounded stress faced by Asian sexual minority men, who navigate both racial and sexual minority identities. The researchers call for more comprehensive studies with larger, diverse samples to further explore these associations and inform targeted interventions. They also emphasize the need for policies that address discrimination and improve access to mental health and preventive care resources for this vulnerable population.

The study’s authors are Lauren L. Chin, Trace Kershaw, Raul U. Hernandez-Ramirez, and

S. Raquel Ramos.

Racism-related stress, health outcomes, substance use, and PrEP attitudes among Asian sexual minority men (Nature, Scientific Reports, published online on February 27, 2025)

Artificial intelligence software was used in the creation of this article.

White-tailed deer play a critical but often overlooked role in the transmission of several tick-borne and mosquito-borne diseases that affect humans, according to a comprehensive new study published in the journal Parasites & Vectors.

The research reveals that deer serve as important hosts for ticks and mosquitoes that spread the causative pathogens for Lyme disease, ehrlichiosis, Eastern equine encephalitis, and other diseases. As deer populations have expanded across the U.S. in recent decades, so too have the geographic ranges of the disease-carrying ticks and mosquitoes.

"White-tailed deer act as reproductive hosts, reservoir hosts, and dispersal agents for ticks and mosquitoes that transmit pathogens of human health concern," said senior author Dr. Goudarz Molaei, PhD, an associate professor adjunct at the Yale School of Public Health and director of the Connecticut Agricultural Experiment Station’s Tick and Tick-borne Pathogen Surveillance Program (also known as Tick Testing Laboratory). "Understanding these ecological relationships is crucial for predicting and preventing vector-borne disease outbreaks."

Key findings include:

• Deer are reproductive hosts for blacklegged ticks and lone star ticks, which spread Lyme disease and ehrlichiosis, respectively.

• Deer serve as reservoir hosts that amplify pathogens like Ehrlichia chaffeensis and Jamestown Canyon virus.

• By carrying ticks to new areas, deer help disperse emerging pathogens like Rickettsia parkeri.

• At least nine mosquito species that can transmit Eastern equine encephalitis preferentially feed on deer.

• Deer provide blood meals for mosquito vectors of West Nile virus and La Crosse encephalitis virus.

The researchers conclude that deer play a multifaceted role in pathogen emergence and spread. They recommend increased surveillance of deer populations as sentinels for monitoring vector-borne diseases. With deer-human interactions on the rise, understanding these dynamics is critical for public health preparedness.

Public health significance of the white-tailed deer (Odocoileus virginianus) and its role in the eco- epidemiology of tick-and mosquito-borne diseases in North America (Parasites & Vectors, published online Feb. 6, 2025)

Artificial intelligence software was used in the creation of this article.

Malaria remains a leading global health challenge, with efforts to control its spread often hindered by insecticide resistance and outdoor mosquito biting. A new study led by researchers at Yale School of Public Health, in collaboration with partners in Burkina Faso, West Africa, and Colorado State University, examined whether mass drug administration of ivermectin could reduce malaria transmission by killing mosquitoes that feed on treated individuals.

The study, conducted over two rainy seasons in Burkina Faso, found that repeated high dose ivermectin treatments were safe, but did not significantly lower malaria incidence in children. However, the intervention led to an improvement in hemoglobin levels among children, suggesting additional health benefits. Researchers also observed a temporary decline in mosquito survival rates in ivermectin-treated villages, though this effect diminished over time.

While ivermectin alone may not serve as a standalone malaria control solution, the study highlights the potential role of this approach in malaria endemic regions. Future research is needed to further explore such novel approaches alongside existing prevention methods.

Dr. Sunil Parikh, MD, MPH, is the study’s corresponding author.

Listen to Dr. Parikh discuss the ivermectin trial and its findings on the Infectious Diseases Today podcast Contagion.

Part I https://www.contagionlive.com/view/insights-from-phase-3-trial-in-burkina-faso-on-ivermectin-s-role-in-malaria-control

Part II https://www.contagionlive.com/view/ivermectin-does-not-reach-primary-endpoint-in-burkina-faso-malaria-trial

Safety and efficacy of repeat ivermectin mass drug administrations for malaria control (RIMDAMAL II): a phase 3, double-blind, placebo-controlled, cluster-randomised, parallel-group trial (The Lancet Infectious Diseases, published online Feb. 4, 2025)

— Janice Hur