vector control
Dengue Explained in Five Minutes
Check out this video by Free Med Education to learn about dengue fever, its cause, and its symptoms.
The Rise of Dengue: A Global Perspective
Around the world, dengue is considered the most common viral disease transmitted by mosquitoes that affects people. According to the World Health Organization (WHO), the disease is now endemic in more than 100 countries. In the first three months of 2024, over five million dengue cases and over 2000 dengue-related deaths were reported globally. The figures so far project that 2024 could be even worse than 2023, with the regions most seriously affected being the Americas, South-East Asia, and Western Pacific.
In the Americas, there were 6,186,805 suspected cases of dengue reported in the first 15 weeks of 2024. To put this into perspective, according to the Pan American Health Organization (PAHO), this figure represents an increase of 254% compared to the same period in 2023. Of these cases 5,928 were confirmed and classified as severe dengue.
Peter DeChant: Vector Control Visionary
The story of Peter DeChant, a veteran in the mosquito and vector control profession whose journey spans over four decades, is one of dedication, innovation, and relentless commitment to combating mosquito-borne diseases.
Peter’s journey began in 1978 when he became a field technician with Multnomah County Vector Control in Portland, Oregon. Little did he know then that this would mark the start of a lifelong crusade against one of the deadliest creatures on the planet.
By 1983, Peter’s skills and passion for his work led him to the role of Chief Sanitarian, where he led the program for 14 years. It was during this time that he honed his expertise and laid the foundation for his future endeavors.
The Economics of Resistance
It would be extremely difficult to calculate, with any high degree of accuracy, the global economic impact of insecticide resistance. For starters, we must consider that insect management plays a pivotal role in a variety of sectors – agriculture, home and garden, forestry, structural applications, and vector control. Analysis of the totality of economic impacts arising from resistance in any one of these sectors quickly becomes a complicated interplay of variables that interact within that given system.
To account for the full economic impact, one must layer in the amount being spent on insect management and how much of that investment is lost to resistance, but also the economic impact of losses to the overarching objectives of a given program.
To calculate the impact, you must first calculate what is at risk.
Birds on the Brink
Hardly anyone visits the desolate outpost of Coldfoot, one of Alaska’s few communities outside the Arctic Circle accessible by road. Its 34 residents live in rustic accommodations along the Dalton Highway. The town’s highlights include an inn, a café, a gas station and a basic airport with a gravel landing strip. All day long, 18-wheeler fuel trucks thunder by on supply runs between Fairbanks and the oil fields of Prudhoe Bay further north. Some will stop to eat and tank up at Coldfoot because the next human habitation is 234 miles away, a town grimly named Deadhorse.
They say Coldfoot got its name from the days of the 1900 Gold Rush when miners would come as far as this remote settlement before getting “cold feet” and turning back. It’s still a lonely place, but one unexpected visitor showed up recently inside an infected Swainson’s thrush (Catharus ustulatus): the avian malaria parasite, Plasmodium circumflexum.
In 2011, scientists tested 676 birds representing 32 resident and migratory bird species captured from three northern locations in Alaska: Anchorage (61°N), Fairbanks (64°N) and Coldfoot (67°N). In Anchorage and Fairbanks, they found 49 birds infected by Plasmodium parasites. In Anchorage, even resident birds and hatchlings of species such as the boreal chickadee (Poecile hudsonicus), the varied thrush (Zoothera naevia) and the fox sparrow (Passerella iliaca) were found infected. The parasite was also detected in black-capped chickadees (Poecile atricapillus) and a myrtle warbler (Dendroica coronata coronata) in Fairbanks, indicating that transmission had occurred locally.
The Economics of Malaria
In the 2022 World Malaria Report, compiled by the World Health Organization (WHO), the total spend on funding the fight of malaria in 2021 was estimated at USD 3.5 billion. Over that year, the same report states that there were an estimated 247 million cases of malaria and 619,000 malaria deaths globally.
More recently, over the course of the 20th Century, malaria is believed to have claimed between 150–300 million lives. The disease is contracted predominantly in the tropical regions: sub-Saharan Africa, Asia and the Amazon basin. This is due to the prevalence of the Anopheles mosquito that transmits the disease. Poorer regions of Africa bear the vast majority of the burden. In 2021, around 95% of the diagnosed cases and deaths were on the African continent, 80% of which were children under the age of five. The disease is entirely preventable and curable with prompt diagnosis and effective methods of treatment which require sufficient investment and funding.
Mosquito-borne Diseases & the Environment
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.
Aedes aegypti: Beyond the Black and White
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.
Vector-borne Diseases & Climate Change
Climate change creates new risks, particularly in the United States, for human exposure to vector-borne diseases (VBDs) — diseases which are transmitted to humans through the bites of insects (referred to as vectors) that carry the disease-causing pathogens. Common vectors include mosquitoes, ticks, and flies.
Climate change creates new uncertainties about the spread of VBDs such as the Zika virus, dengue fever, malaria, and Lyme disease by altering conditions that affect the development and dynamics of the disease vectors and the pathogens they carry.