A domestic resurgence of U.S. malaria cases for the first time in 20 years has raised concerns about mosquito-borne diseases and how to prevent them. The Centers for Disease Control and Prevention (CDC) issued a health advisory on June 27 after five malaria cases were confirmed in Florida and Texas. This number has continued to rise, with Florida reporting two additional cases, bringing the total in the U.S. to seven so far. While globally, malaria poses a larger threat, affecting nearly half of the world’s population, the recent local cases emphasize the need for effective prevention methods.
Mosquitoes are known to transmit various diseases to humans, including West Nile virus, malaria, yellow fever, Zika virus, dengue, and chikungunya virus. However, it is important to note that getting sick from a mosquito bite is relatively uncommon. The most common mosquito-borne disease in the United States is West Nile virus, with 17 cases reported by the CDC as of June 27. However, eight out of 10 people infected with West Nile do not develop symptoms. Those who do may experience fever, headache, disorientation, and other neurological symptoms.
Malaria, on the other hand, is a serious and sometimes fatal disease that spreads to humans through the bite of an infective Anopheles female mosquito. Symptoms typically appear within seven to 30 days but can take up to a year to develop. While malaria is easily treatable, it can cause high fevers, shaking, chills, and flu-like symptoms. In rare cases, failure to treat the condition promptly can lead to chronic infection with relapsing episodes. Malaria is generally rare in the United States, with only around 2,000 cases reported annually. Most cases are acquired through travel, and there have only been 150 cases of locally acquired malaria in the past 50 years. However, the disease remains a significant problem in sub-Saharan Africa, particularly among children.
Zika, a mosquito-borne disease transmitted by the Aedes species of mosquito, was a concern in the United States in 2016 and 2017, with multiple cases reported. However, there have been no locally acquired Zika cases reported since then. Yellow fever, another mosquito-borne disease, is also rare in the United States, and there is no medical treatment for it. Most people fully recover from yellow fever within a few days. Dengue, which is spread by the Aedes species of mosquito, saw 1,188 cases confirmed in the United States last year, but only a quarter of those infected experience symptoms, and most recover within a week. The first controversial vaccine for dengue was approved by the Food and Drug Administration (FDA) in 2019 for children ages 9 to 16 who have laboratory-confirmed previous dengue infection and live in endemic areas. However, there is no medical treatment available for the disease. Chikungunya virus, another mosquito-borne illness, is rare in the United States, with most cases acquired during travel. There is no medication to treat or prevent the disease.
Preventing mosquito-borne diseases primarily involves preventing mosquito bites. While chemical repellents like DEET and permethrin are commonly recommended by regulatory agencies, these synthetic products can have detrimental effects on both humans and the environment. DEET, in particular, has a long history of recommendations despite evidence of harm. It can cause neurological symptoms, adverse reactions, and even neuropathological lesions in the brain at high doses. Permethrin, another commonly used pesticide, is highly toxic to beneficial insects and has negative effects on the human nervous system. Simultaneous exposure to multiple chemicals, including DEET and permethrin, may lead to symptoms associated with Gulf War syndrome.
In addition to these chemical repellents, the CDC also recommends picaridin, IR3535 oil, and lemon eucalyptus oil as alternatives. However, the agency does not recommend using essential oils. Furthermore, there are natural and nontoxic ways to prevent mosquito bites that have been found to be equally effective. Plant-based repellents containing bioactive phytochemicals have shown promise in various studies as safe alternatives. Some examples include Ligusticum sinense extract, Citrosa plants, and essential oils from eucalyptus and lemon. These natural alternatives are biodegradable and pose fewer risks to human health and the environment.
Apart from preventing mosquito bites, creating an environment that is unfavorable to mosquitoes can also help reduce the risk of mosquito-borne diseases. This involves removing standing water around homes, repairing damaged screens on windows and doors, using UV light traps to catch mosquitoes, reducing warm temperatures and humidity with air conditioners, dehumidifiers, and fans, timing outdoor activities to avoid peak mosquito hours, wearing protective clothing, washing off sweat promptly, using smoke from an outdoor firepit, and using citronella candles.
While the recent resurgence of malaria cases in the United States is concerning, it is important to approach prevention methods with a comprehensive and balanced approach that takes into account both human health and environmental impact. By exploring natural alternatives and implementing practices that create an unfavorable environment for mosquitoes, we can work towards reducing the transmission of mosquito-borne diseases and safeguarding public health.
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