Vector-borne disease vs chemicals in bug spray: Weighing the risks

By Michelle M. Forman, senior media specialist, APHL

Vector-borne disease vs chemicals in bug spray: Weighing the risks | www.aphl.orgWith hot and humid weather comes news of diseases spread by mosquitos and ticks, while we also hear of concerns around the bug sprays we’re supposed to use to protect ourselves. What exactly are people supposed to do? Which pieces of information should you believe? How are you to decide the best way to protect yourself and your family from bites, disease AND harmful chemicals all at the same time? At this point, locking yourself inside until winter might seem like the only option.

Not to worry. The important thing is to consider whether the risks associated with each vector-borne disease are more or less worrisome than the risks associated with the chemicals found in bug sprays. Here is our breakdown of those risks.

While vector-borne diseases refer to illnesses transmitted by many tours of insects, we’re going to focus on mosquitoes and ticks here.

Note the severity of each vector-borne disease and impacts of applications described below may differ based on individual conditions such as age, predetermined health status, access to healthcare, etc. If you have any questions or concerns, please speak with your physician.

Mosquito-Borne Diseases

West Nile virus (WNV)WNV is found in all 48 contiguous states. The number of cases annually varies. 2012 was the deadliest year with 286 deaths.

  • The bad news: Those who show symptoms will typically have headache, body aches, joint pain, vomiting, diarrhea and/or rash within about a week of the infectious bite. In some cases, fatigue and weakness can last for months. In more severe cases, people can even develop neurologic conditions like encephalitis or meningitis. About 10% of those people will die. There are no medications or treatments for WNV aside from pain medication to reduce fever or relieve some of the symptoms. Those experiencing the most severe symptoms may be hospitalized.
  • The good news: Not every person bitten by an infected mosquito will show symptoms.

Eastern equine encephalitis virus (EEEV) – In the United States, an average of six human cases of EEE are reported annually. Cases mostly occur in the Atlantic and Gulf Coast states, although there have been some cases in the Great Lakes region as well.

  • The bad news:  EEE can be very serious. Severe cases will experience headache, high fever, chills and vomiting which could progress into disorientation, seizures, encephalitis and coma. Approximately one-third of patients who develop EEE die, and many of those who survive have mild to severe brain damage. Some of the long-term effects can cause death years later. There is no specific antiviral treatment for EEE; people showing symptoms should see their healthcare provider who can determine if supportive treatment is necessary and available.
  • The good news: Most cases will not show any symptoms, and only about 4-5% of EEEV cases become EEE.

Chikungunya – While there have only been four reported cases of locally acquired chikungunya in the US, experts are concerned because the disease spreads so rapidly. Chikungunya first reached the Caribbean in December 2013 and by March 2014 there were 15,000 reported cases.Chikungunya has now been identified in nearly 40 countries in Asia, Africa, Europe and, most recently, the Americas.

  • The bad news:  Nearly everyone who is bitten by an infected mosquito will develop fever and joint pain; other symptoms may also include headache, muscle pain, joint swelling or rash. The joint pain is often very debilitating, but usually lasts for a few days or possibly weeks. In some cases joint pain may continue for months or years. There have been some reports of lasting gastrointestinal, eye, neurological and heart complications. There is no treatment for chikungunya aside from over the counter pain medication to reduce discomfort.
  • The good news: Most people fully recover.

Dengue virus – According to CDC, there are over 100 million cases of dengue worldwide each year. It is a leading cause of death in many tropical areas of the world. While it is not typically found in the continental US, dengue is endemic in Puerto Rico and many parts of Latin America, Southeast Asia and the Pacific Islands where Americans vacation.

  • The bad news: Typical symptoms include high fever, severe headache, severe pain behind the eyes, joint pain, muscle and bone pain, rash, and mild bleeding (e.g., nose or gums bleed, easy bruising). Dengue hemorrhagic fever, a more severe form of dengue virus, is characterized by a fever that lasts from 2 to 7 days. It can be fatal if unrecognized and not properly treated in a timely manner.
  • The good news: Early detection and treatment will lower the rate of fatality to below 1%.

Tick-Borne Diseases

Lyme – According to CDC, Lyme disease is the most commonly reported vector-borne illness in the United States with over 20,000 cases annually. However it does not occur nationwide, but tends to be heavily concentrated in the northeast and upper Midwest.

  • The bad news: Bulls-eye rash occurs in 70-80% of infected people. Other symptoms include fatigue, chills, fever, headache, muscle and joint aches, and swollen lymph nodes. 10-20% of cases treated with antibiotics have muscle and joint pains, cognitive defects, sleep disturbance, or fatigue that lasts months or even years. In extremely rare cases (1% of cases), Lyme disease bacteria can enter the heart tissue causing Lyme carditis which can be fatal.
  • The good news: Patients can be treated with antibiotics and the prognosis is best when treatment begins early.

Rocky Mountain Spotted Fever – Spread through the bite of an infected tick, Rocky Mountain Spotted Fever occurs throughout the US.

  • The bad news: Symptoms typically begin with a sudden fever and headache, but many patients will eventually develop a rash, stomach pain, nausea, fatigue or muscle aches. (Not all cases develop every symptom.)  Severe cases can lead to life-long complications such as neurological problems and internal organ damage.  In extremely rare cases (less than 1% of cases), Rocky Mountain Spotted Fever can be fatal. Diagnosis can be difficult as the symptoms can resemble other conditions, and diagnostic tests looking for antibodies are often negative within the first 7-10 days. Treatment is most successful if started in the first five days.
  • The good news: While the number of cases has been higher than usual, the fatality rate is at an all-time low.

Bug Spray – These chemicals have been determined to be the most effective in preventing mosquito and tick bites:

DEET

  • The bad news: DEET has been linked to various health risks such as skin irritation, eye irritation and even neurological damage. But those cases are very rare, and many studies have found the connection between DEET and serious health risks to be inconclusive.
  • The good news: DEET is widely regarded as the most effective chemical in personal bug repellant. The stuff works! Better yet, using DEET with caution appears to significantly limit any serve risks; in fact, many now feel that DEET is safer than once believed. By using lower concentrations (10-30% for children), only using when it is necessary and following the instructions on the label the benefits of DEET far outweigh any risks.

Picaridin

  • The bad news: Picaridin has not been as effective for as long a period of time as DEET in some studies. It also does not protect against all species of mosquitoes. Picaridin is also a relative new kid on the block, so surveillance data is still lacking.
  • The good news: Picaridin is structurally made from the chemicals in pepper, so it is more natural than DEET. It is less likely to irritate skin, doesn’t have the same strong odor as DEET and seems to have a safer profile than DEET.

IR3535

  • The bad news: Concentrations of less than 10% were considered ineffective. IR3535 can be very irritating to the eyes, and has been shown to damage plastics.
  • The good news: IR3535 has been used in Europe for over 20 years. It has a safer profile than its competitors.

Oil of lemon eucalyptus and para-menthane-diol (PMD – synthetic concentration of lemon eucalyptus oil)

  • The bad news: Oil of lemon eucalyptus enhanced with PMD is not recommended for children under the age of 3. It can be irritating to the lungs and cause possible allergic reactions. Protection time seems to be less than DEET.
  • The good news: Higher concentrations seem to be as effective as 15-20% DEET. While lower concentrations will reduce the risk of allergic reaction and lung irritation, they are considerably less effective in repelling mosquitoes and ticks. For those insisting on a botanical bug spray, this is considered the best option.

So what’s the answer to our initial questions? Well, it isn’t really that easy. There is no one right answer for every person in every situation. Vector-borne diseases present a serious health risk that should be avoided. DEET is the most effective chemical for repelling insects available, and studies have shown that risk is low and effectiveness is still high when using concentrations under 30%. The other chemicals listed above may also be reasonable options for you and your family.

Our recommendation: The benefits associated with the chemicals far outweigh the risks. Wearing long pants and sleeves, wearing a hat and eliminating standing water will also help decrease the risk of mosquitoes and ticks. But the best way to avoid vector-borne diseases is to use bug spray when you are in an area with a high number of mosquitoes and ticks.