Cracking the code of mosquito-borne disease outbreaks

Tereza Magalhaes, Ph.D., is living an old, oft-used adage: “Science saves lives, one discovery at a time.”

Magalhaes, a vector biologist in the Texas A&M College of Agriculture and Life Sciences Department of Entomology, grew up in Brazil in a family of scientists and academics, and she developed her natural interest in biology from an early age. Her aunt would tell Magalhaes she would be a detective one day.

Magalhaes lacked a solid idea of the research she would pursue, but she knew she wanted to be in a lab and that her work should improve people’s lives.

She eventually discovered her scientific passion – bridging entomology, epidemiology and public health – and has become a leading expert in the field.

Investigating outbreaks protects public health

In her role today, Magalhaes is as much detective as scientist. She investigates the complex relationship between insects and arboviruses, which are pathogens transmitted by arthropods, including mosquitoes and ticks. Magalhaes’ current research focuses on four mosquito-borne diseases – Zika virus, dengue fever, chikungunya and Madariaga virus.

Her goal is to better understand how those diseases spread, why their transmission varies in time and space, and to help develop tools and methods that mitigate outbreaks. Magalhaes’ lab and research helps public health officials tailor prevention and control measures at local and global levels.

“There has always been an emphasis within my family that science can impact people’s lives directly,” she said. “Some of these diseases have a greater impact on vulnerable populations in Brazil and other tropical regions, but overall vector-borne diseases are a growing global problem also affecting populations living in more temperate areas.

“We’re working now to be prepared for diseases that have not established in Texas and the U.S. before they create a public health crisis.”

Vector biologist finds strength, solutions in collaboration

Much of Magalhaes’ work revolves around discovering and deciphering the complex factors that contribute to outbreaks. Environmental factors like temperature and rainfall can set the stage for mosquito populations, but understanding disease transmission patterns takes a multifaceted, interdisciplinary approach.

Magalhaes collaborates with a wide range of experts at Texas A&M AgriLife as well as nationally and internationally. Scientific fields such as insect physiology, virology, genetics, epidemiology, ecology, and medical and veterinary entomology as well as disease modeling all contribute to solving the puzzle these diseases present. 

She believes identifying and understanding factors that fuel outbreaks can lead to tools public health officials can use to forecast potential problems and mobilize to mitigate transmission.

“Interdisciplinary collaboration is important for all research, but this type of work, especially, depends on access to others’ expertise,” she said. “Our skills are complementary and shape and strengthen the research, helping us answer key questions about these diseases.”

Arboviruses present global challenges

Magalhaes said Zika, dengue and chikungunya are a research priority because they present public health concerns in the U.S. and globally. The diseases impact humans in a variety of ways, from flu-like symptoms to the development of neurological conditions and prenatal issues. They can even cause death.

Modern travel gives vector-borne disease research global relevance. The confluence of factors that can fuel an epidemic in one country can produce or set the stage for subsequent outbreaks in other parts of the world.

The Zika virus is a good example. The disease presents mild symptoms like rash, fever and joint pain but also major public health concerns, including miscarriages, malformations and a range of brain abnormalities in babies.

Cases have been reported in Africa and Asia since the 1960s, but the virus gained more attention in the mid-2010s. In the Western Hemisphere, the first case of Zika was reported in Magalhaes’ home country, Brazil, in 2015. The disease rapidly spread through Latin America, and there were more than 60 Zika cases in the U.S. that year. The disease became endemic in parts of Latin America, but it has so far failed to establish in the U.S.

Public panic throughout the Americas during the 2015 outbreak spurred action by public health officials and scientists. Scientists, including Magalhaes, provided recommendations including mosquito abatement programs and educational material focused on transmission prevention. The outbreak waned.

“We’re still trying to understand why Zika was so explosive,” she said. “When Zika exploded in Brazil, scientists there started making the association between Zika virus infection and microcephaly in babies, and that was groundbreaking.”

Meeting new and emerging threats

While arboviruses such as Zika are a greater threat where they are endemic, Magalhaes said travel-related cases show that these viruses continue to be a threat domestically. Knowing the factors that contribute to their transmission is critical to control the disease and prevent establishment in the U.S.  

Magalhaes said an important discovery determined that Zika could be spread from person to person through sex. Many questions remain unanswered, but subsequent research by Magalhaes included data modeling showing sexual transmission could increase exposure and likely acted synergistically with mosquito transmission in Zika’s explosive spread between 2015 and 2017.

“The key point is that these diseases are no longer limited to ‘hotspots’ in endemic regions, and there are still surprises ahead, as in the case of Zika where other relevant modes of transmission beyond mosquito bites were discovered,” Magalhaes said.

Zoonotic arboviruses like Madariaga virus pose additional risks for establishment as the disease can be carried by wildlife and livestock.

Madariaga mostly impacts horses but can also cause severe disease and death in humans. There is evidence that risk to humans is increasing. It is related to the eastern equine encephalitis virus, which mainly affects children and older adults, and is primarily found in Central and South America.

“When I started studying Madariaga, I realized it is a widespread virus that has been causing encephalitis in horses for decades and is now being detected in humans every once in a while,” she said. “It represents a potential emerging pathogen that affects human and animal health, and we are conducting several studies on it so that we are well prepared should the need arise.”

Staying ahead of crisis

Magalhaes stressed the importance of research into monitoring and prevention in the fight against mosquito-borne diseases.

She is proud to be on the front line of that fight, and happy her chosen field allows her to shift with public health priorities.

For example, West Nile is an arbovirus endemic to the U.S. that she could easily apply her work to, and ticks are disease-carrying arthropods she may consider studying in the future.

“Public health and animal health priorities can be tricky when it comes to these diseases,” she said. “Priorities can be driven by crisis, but the goal is to stay ahead and help avoid a crisis. There are always new scientific discoveries to make in that fight, and that is what makes this field important.”