Vector-borne diseases in Arizona

April 11, 2023

Vector-borne diseases are human illnesses caused by different parasites like bacteria and viruses that are transmitted by vectors. Vectors are living organisms that transmit disease-causing parasites from animals to humans or between humans. For example, mosquitos are a vector for transmitting diseases like yellow fever. Some other vectors are ticks, lice, sandflies, fleas, etc. In the United States, the most common vector-borne diseases are transmitted by mosquitoes or ticks. These diseases include Zika, dengue, West Nile fever, Rocky Mountain spotted fever, and Lyme disease. The most common vector-borne diseases in the southwestern United States (including Arizona) are: West Nile, Rocky Mountain spotted fever, Hantavirus pulmonary syndrome, and plague. 

West Nile outbreaks are reported each summer in the United States, and the deadliest outbreak occurred in 2012. About 1 in 5 infected people develop symptoms like body aches, headache, pain in joints, rash, vomiting, or diarrhea. In case of severe illness, the symptoms may include high fever, stupor, neck stiffness, tremors, vision loss, coma, numbness, paralysis, etc. People over 60 years of age or people with medical conditions like cancer, diabetes, hypertension, and kidney disease, and those who have received organ transplants are at greater risk for severe illness. Last year Arizona recorded 1,693 human cases of West Nile virus with 121 fatalities.,last%20for%20weeks%20or%20months.

 Rocky Mountain Spotted Fever is a bacterial disease transmitted by brown dog ticks in Arizona. The number of cases is rising in Arizona, and the number of cases peaks in July through September. Most people with the infection get fever, headache and rash. It can be deadly if not treated early. 

Hantavirus Pulmonary Syndrome is a viral disease transmitted by rodents. The early symptoms include fever, dry cough, headache, body ache, dizziness, chills, vomiting/nausea, abdominal pain, and diarrhea. Symptoms like severe cough and shortness of breath develop if not treated on time and can lead to severe organ failure and death. 

Lyme disease is caused by a bacterium and transmitted by ticks. Early symptoms include malaise, fever, fatigue, stiff neck, headache, myalgias, migratory arthralgia, and lymphadenopathy. The most common symptom is a bull’s eye rash. Even though this disease is not present in Arizona, every year, Maricopa County has 1-10 confirmed cases due to travelers arriving in Arizona. 

Many vector-borne diseases are preventable through protective measures like alteration of a vector’s habitat and/or removal of the vector’s food source. In the state of Arizona, vectors like mosquitos are most prevalent between March and October. The best way to prevent mosquito-borne disease is to remove standing water sources to prevent mosquito breeding and to prevent mosquito bites. For details, please check the Arizona Department of Health Services at: