Zika: What Has Mosquito Control Taught Us?
One Big Question with Gordon Patterson
In nature’s great blood-and-sex drama, mosquitoes are indisputably the senior participants. Taxonomists place mosquitoes in the Diptera (flies) order of the Arthropod phylum, which emerged more than 200 million years ago. Entomologists have identified more than 3,500 species of mosquitoes belonging to the Culicidae family of the Diptera order. On average 18 new species are classified each year. Scientists estimate there are roughly 170 different species of mosquitoes in the United States, and more than 75 species in Florida. As in other fields of scientific endeavor, the privilege of naming newly discovered species goes to the discoverer. Names such as Haemagogus lucifer, Ochlerotatus tormentor and Psorophora horrida suggest something of the quality of the relationship between our species and the family of six-legged-bloodsucking pests.
The Zika virus (ZV) pandemic has again reminded us that no creature has posed a greater threat to human beings than this tiny insect. ZV was first identified in 1947 near Entebbe, Uganda. Five years later researchers confirmed the role of mosquitoes in the virus’ transmission. The first clinically documented human case of Zika came a year later in Nigeria. During the next 50 years, ZV was considered a mild disease producing flu-like symptoms in 1 in 5 individuals who contracted the virus. Between 1947 and 2007, the World Health Organization (WHO) reported there were only 14 documented cases ZV. In 2007, the first large ZV outbreak took place on Yap Island in the Federated States of Micronesia, where an estimated 73% of the population had been infected. During the next 8 years, ZV made its way to French Polynesia, Easter Island, reaching South America in 2015. In October 2016, the Pan American Health Organization (PAHO) confirmed ZV’s presence in 47 countries and territories in the Western Hemisphere. In Brazil alone, it is estimated there have been between 500,000 and 1 million ZV cases.
The discovery that ZV can cause serious birth defects, a spectrum of pregnancy problems as well a rare neurological disorder producing paralysis (Guillain-Barré syndrome) has sparked a worldwide campaign to find a cure for the disease.
What do we know and what can we do?
First, ZV is vectored by mosquitoes and can be transmitted through sexual contact. Second, at present there is no cure or vaccine for ZV. Third, mosquito control is the principal means of preventing the spread of ZV. There are practical steps that can be taken. The species of mosquitoes (Aedes aegypti and Aedes albopictus), which are the ZV’s primary vectors, are container breeders with a short flight range (100–200 yards). One hundred years ago medical entomologists, sanitarians, engineers and physicians waged successful campaigns against these disease-bearing insects through mosquito control.
Recently, the American Mosquito Control Association reminded citizens of some of the lessons that can be learned from the past:
The “3 Ds” of mosquito control:
1. Dump and Drain.
2. Dress appropriately.
3. Defend, use repellents.
These are practical steps that each of us can take to protect our families, neighbors and communities.
The development of mosquito control in the 21st century will in large measure be determined by the success of control efforts in facing the challenge posed by the resurgence of dengue fever, malaria and the appearance of Zika on the world stage. Mosquito control and, in the case of Zika, the practice of safe sex, remain the only means to break the transmission cycle of mosquito-borne pathogens.
If there is a lesson in the history of mosquito control, it is that there are no “magic bullets.” Protecting the public from pathogen bearing and nuisance mosquitoes depends on research to improve mosquito control and an abiding respect for the environment. When at its best, mosquito control is applied ecology. For now, each of us must do our part in “Fighting the Bite.”
Gordon Patterson, professor of history, came to Florida Tech in 1981. He is the author of “The Mosquito Wars” and “The Mosquito Crusades.” In 2010, he was awarded the Presidential Medal from the American Mosquito Control Association. In 2014, he was invited to lead the Bloomberg School of Public Health Department of Molecular Biology and Immunology Seminar at Johns Hopkins University.