Mosquito-borne diseases, such as West Nile virus and Zika virus, are illnesses passed from mosquitoes to humans and animals.

Mosquitoes are small, fly-like, and feed on the blood of people and animals. Female mosquitoes bite people and animals, feeding on their blood. Male mosquitoes do not bite people and instead eat plant nectar. Female mosquitoes need these blood-meals to lay eggs. During these feedings, they can transmit disease-causing viruses or parasites.

The following mosquitoes are found in the DC-area: common house mosquito (Culex pipiens), Asian tiger mosquito (Aedes albopictus), and yellow fever mosquito (Aedes aegypti).

Diseases that these mosquito species can carry and transmit include:

• Cache Valley virus 
• Chikungunya virus 
• Dengue virus 
• Eastern equine encephalitis 
• Heartworm disease (in people and dogs) 
• Jamestown Canyon virus
• Japanese encephalitis 
• LaCrosse virus 
• Saint Louis Encephalitis
• Venezuelan equine encephalitis 
• West Nile virus 
• Western equine encephalitis
• Yellow fever 
• Zika virus

Not all mosquitoes carry the same diseases. Different species transmit different diseases. The species of a mosquito can be identified by its coloring and patterns. Refer to the following link for a guide on different mosquito species and what diseases they can carry: Mosquitoes: What to Know?

 

Mosquito Bite Prevention

Regardless of the species of mosquito, preventing mosquito bites and exposures is the same.

►The best way to prevent mosquito-borne diseases is to avoid mosquito bites by repelling mosquitoes, covering exposed skin, keeping mosquitoes outside, eliminating standing water, controlling mosquitoes, and being aware of mosquito-borne diseases common in different parts of the world before you travel outside the U.S.

 

• Repel: Use Environmental Protection Agency (EPA)-registered insect repellents with one of the following active ingredients: DEET, Picaridin, IR3535, Oil of lemon eucalyptus (OLE), Para-menthane-diol (PMD), or 2-undecanone.
  • To protect pet dogs and cats keep them on monthly heartworm prevention and test regularly for heartworms (typically once per year).

• Cover: Wear long-sleeved shirts and long pants

• Keep mosquitoes outside: Use air conditioning or window and door screens. If you are not able to protect yourself from mosquitoes inside your home or hotel, sleep under a mosquito bed net.

• Eliminate standing water: Mosquitoes lay their eggs in stagnant, still water. Eliminate mosquitoes from doing this by turning over, covering, or throwing out things that can hold water such as:
  • vases
  • pet water bowls
  • flowerpot saucers
  • used tires
  • buckets
  • pool covers
  • birdbaths
  • trash cans
  • rain barrels

You can also empty and scrub these items once a week to stop mosquitoes from using them.

• Control mosquitoes: Eliminating standing water reduces the need to control larval and adult mosquitoes. If standing water cannot be eliminated, mosquitoes can be controlled using EPA approved larvicides or adulticides. DC Health actively larvicides sources of standing water that cannot be eliminated but does not adulticide. Private residents are allowed to hire pest controls companies to apply adulticides on their property if they wish.

• Know before traveling: While mosquitoes in DC can carry West Nile virus, there are diseases they have never been found to carry such as Dengue fever, Chikungunya virus, and Zika virus. You are much more likely to get these diseases from mosquitoes in other regions of the world, especially tropical regions. To check if a certain mosquito-borne disease is common in a country where you are planning to travel go to the CDC Travel Health Notices webpage and enter the country name in the search box. The World Health Association (WHO) also has a webpage related to mosquito-borne diseases found throughout the world but not commonly found in the U.S. Regardless of what mosquito-borne diseases may be found where you travel, you can still protect yourself by following the steps highlighted earlier. For additional health information on traveling internationally visit the DC Health Traveler Health Information webpage.

DC Health Mosquito Surveillance Results

Since the year 2000, DC Health has conducted comprehensive surveillance of the types of mosquitoes found in the District of Columbia. This includes testing captured mosquitoes for West Nile virus. Below are weekly reports and summaries of the most recent surveillance year:

2021
2018

Information for Human Healthcare Providers

Reporting mosquito-borne diseases in people

All cases of mosquito-borne diseases in a person should be reported using DC Reporting and Surveillance Center (DCRC), our online reporting system.

• Submit a Notifiable Disease and Condition Case Report Form using DCRC

Diagnosis and Treatment

When treating patients for mosquito-borne diseases, keep in mind that most diseases present the same clinically, can only be differentiated with diagnostic testing and treated symptomatically. The following guide lists common clinical features of some mosquito-borne diseases: Mosquito-Borne Disease Clinical Comparisons

Mosquito-borne Disease Resources for Human Healthcare Providers

• Arboviral Disease Surveillance Report 2019 – 2022  
• Webinar about reporting VBDs to DC Health
• CDC Health Information for International Travel (the Yellow Book) 
• CDC Traveler’s Health
• Visit DC Health’s West Nile virus or Zika virus webpages for information specific to those diseases

Information for Animal Healthcare Providers

Mosquito-borne Disease Resources for Animal Healthcare Providers

• Mosquito control measures in animal shelter settings 
• Mosquitoes (Merck Veterinary Manual)

DC Health Contact Information

For more information on mosquito-borne diseases call (202) 442-9143 or email [email protected].