In the last couple of decades, the lush rainforest around the remote village of Meliandou in the heart of Guinea has become patchier. Animals, like bats, saw their habitats dwindle and in a quest for survival, they sought refuge in closer proximity to human environments, making the boundaries between species thinner. A hollowed-out tree in the middle of the village became home to a colony of bats.
About 50 meters from the same tree, in the heart of Meliandou, a two-year-old boy named Emile lived with his family. In a matter of days, Emile fell ill with an unknown virus, developed a high fever, and died. Soon the same virus, that scientists now believe Emile got from the bats, took the lives of his sister, mother, and grandmother. The village, surrounded by a ring of forest, unexpectedly became the epicenter of a devastating outbreak that would leave an indelible mark.
Dr. Raman Velayudhan is a seasoned expert in the public health field and a relentless advocate for combating the global threat of mosquito-borne diseases.
Currently at the helm of the Veterinary Public Health, Vector Control, and Environment unit within the Department of Control of Neglected Tropical Diseases at the World Health Organization (WHO), Dr. Velayudhan’s impact is far-reaching.
Climate change and human activity are enabling the spread of mosquito-borne diseases, like dengue fever, to new places. Stanford infectious disease experts and disease ecologists discuss what we know and how communities can protect themselves from these changing disease threats.
One look at Aedes aegypti gives an immediate impression of its menacing nature. The telltale dark and white bands on the mosquito’s legs and other body parts bring a sense of foreboding and hardship. Sleek, silent, and stealthy, Ae. aegypti is the primary vector for several important, debilitating, and sometimes fatal human diseases including dengue, Zika virus, yellow fever, and chikungunya. The species is cause for mounting concern on many levels, as its biology, behavior, and ability to adapt have made Aedes aegypti one of the most pervasive and daunting public health challenges in the modern world.
The first mosquito ever associated with the spread of disease, Ae. aegypti is also the most studied of all mosquito species.1 From its humble beginnings in the African wild to a footprint that spans the globe, this durable and opportunistic insect has become a formidable opponent of vector control efforts worldwide.
Clean water is essential for all life on Earth to thrive. The water cycle is not contained within our countries’ borders or boundaries, which makes it a challenge to monitor, maintain and implement improvements and changes. Ownership of, and access to, this essential natural resource has been at the forefront of many disputes around the world, between neighboring countries and communities, and even countries on opposite sides of an ocean. Across the globe we are observing conflicts, wars and water refugees as people struggle for equal access to what has been widely termed as Blue Gold.
Economies on both a national and local level depend upon clean freshwater and saltwater regions. In theory, a thriving economy has the ability to fund infrastructure projects and provide basic needs for all of its citizens. However, even wealthy countries are struggling to provide sufficient standards of clean water, with each region negotiating its own bespoke complications.
The burden of vector-borne diseases (VBDs) is one of public health’s most pressing challenges. VBDs are caused by pathogens such as arboviruses (arthropod-borne virus), bacteria, and parasites that are transmitted to humans and animals through the bites of infected arthropods including mosquitoes, ticks, sandflies, and fleas, among others. According to the World Health Organization (WHO) , “vector-borne diseases account for more than 17% of all infectious diseases, causing more than 700,000 deaths annually worldwide”.
Beyond these broad statistics, attempts to quantify the global burden of VBDs is extremely challenging – for a number of reasons. At the highest level, even “burden” has an underlying complexity in public health terms: burden may refer to the number of cases of a given disease as well as the number of deaths.
Burden can also represent Disability-adjusted Life Years (DALYs), a measure that accounts for the long-term effects of disability among the afflicted, as well as the economic impact of disease from regions and countries all the way down to households and individuals. These economic impacts can be further scrutinized as reduced productivity among the populace, increased healthcare costs, and negative impacts on tourism; all of which can directly affect the GDP and economic growth of local and regional economies. And that’s just the beginning.
Each year on April 22nd, people and nations around the world celebrate Earth Day to raise awareness and promote action toward environmental protection and sustainability. Activities typically include community clean-ups and educational campaigns designed to promote sustainability in daily life.
The origins of Earth Day date back to the 1960s and a decade of growing enviro-consciousness brought about by the publication of Rachel Carson’s Silent Spring and a series of environmental disasters that climaxed with a devastating oil spill off the coast of California in 1969. Gaylord Nelson, a U.S. Senator from Wisconsin, organized the first Earth Day in 1970, when an estimated 20 million Americans took part in organized activities ranging from tree plantings to beach cleanups and teach-ins on college campuses.
Since those humble beginnings, Earth Day has become a global event – but amidst the tree plantings and landscape revitalization lies a subtle and yet direct connection between Earth Day and Public Health. Just as we depend on the natural environment for our survival, civilization creates and shapes a social and economic environment that greatly influences the health and well-being of our species.
The challenges faced by the global health and healthcare sector are set to continue in the future. The near-term issues include worsening mental health, healthcare workforce shortages, supply chain issues, climate change-related challenges and macroeconomic instability. The longer-term challenges include growing demand for services, an increasing funding gap, a lack of incentives for innovation, widening disparities in overall health and wellness, and variable access to advanced therapies.
As we approach World Health Day on 7 April, here are eight current global health and healthcare trends we need to contend with as we aim to transform systems to become more sustainable, resilient and equitable.
Doctor Shinji Kasai’s recent publication on the combined effects of three knockdown resistance (kdr) mutations in Aedes aegypti sparked media frenzy. He demonstrated the causal relationship between specific genes & pyrethroid sensitivity in mosquitoes.
The study improved understanding of insecticide resistance evolution & opened new strategies to control mosquito populations & reduce disease spread. Kasai’s latest paper on super-insecticide-resistant dengue mosquitoes caused a stir in the media, revealing high levels of pyrethroid resistance in field populations.