Vector-borne Diseases

Vector-borne diseases (VBD) are viruses and bacteria spread by vectors including mosquitoes, ticks and fleas, and they can cause a variety of illnesses in humans. ​​The vectors ingest the microorganisms from an infected host and transmit to a new host through a bite. Many public health laboratories test for VBDs that are endemic (see list below) as well as those emerging or re-emerging in the US.

APHL works with CDC and public health laboratories to promote best practices, develop guidance and hold important laboratory trainings related to the most commonly found vector-borne diseases in the country. Public health laboratories are integral to performing high quality testing to assess regional disease burden and inform the nation's response to vector-borne diseases.

Emerging Issues

Oropouche virus 

Oropouche virus (OROV) was initially identified over 70 years ago is considered endemic to the Amazon basin and certain Central and South American countries. Transmitted by biting midges which are small flies, often called "no-see-ums," the virus was identified as causing large outbreaks in 2023 and continued unprecedented levels of transmission across the Caribbean as well as South and Central America. Identification of possible cases of vertical transmission between mother and fetus are being investigated. 

Preliminary diagnosis is based on the patient's clinical symptoms, location where infection likely occurred and activities leading to risk of exposure. Clinical and surveillance testing is currently limited and should be coordinated through state and local public health laboratories/departments.  

For patients meeting the suspect case definition, CDC can perform CLIA-validated testing using RT-PCR to detect OROV RNA and/or PRNT to detect neutralizing OROV antibody on serum and/or CSF. Further information on CDC testing, reporting and management of cases can be found in the interim CDC documents below. 

Interim CDC Guidance Documents: 

• Interim Guidance for Health Departments on Testing and Reporting for OROV Disease (CDC) (Updated 9/10/24)
  

• Interim Guidance for Evaluation and Management of Infants Born to Pregnant People with Confirmed or Probable OROV Disease (CDC) 

• Interim Clinical Considerations for Pregnant People with Confirmed or Probable OROV (CDC)
  

Additional Information:

• About Oropouche (CDC)
  
• HAN: Increased Oropouche Virus Activity and Associated Risk to Travelers
  
• Oropouche virus disease among travelers — United States, 2024 (MMWR Publication) 
  
• Prevention (CDC) 
  
• Travel Notices: General, Cuba  (CDC)
  
• Epidemiological Alert (PAHO) 
  

Dengue virus 

APHL continues to monitor the unprecedented number of dengue cases in 2024 and is coordinating with federal partners and public health laboratories to ensure appropriate and sufficient laboratory testing to identify DENV. 

Learn more about the ongoing outbreak and find relevant resources. 

Endemic Vector-borne Di​seases

There are several endemic VBDs of public health concern within the US including those listed below. These VBDs are not equally distributed and therefore testing within a particular public health laboratory may only include some of the pathogens. 

• Borrelia burgdorferi (Lyme Disease)​
• Colorado Tick Fever Virus (CTFV)
• Eastern Equine Encephalitis Virus (EEEV)
• Jamestown Canyon Virus (JCV)
• LaCrosse Encephalitis Virus (LCV)
• Powassan Virus
• St. Louis Encephalitis Virus (SLEV)
• West Nile Virus (WNV)

APHL Resources

• Suggested Reporting Language for Lyme Disease Serologic Test results (2024) 
  

• Standard Two-Tiered Testing Algorithm (STTT): Algorithm and Reporting Language (For Best Resolution, Print 11x17)
  

• Modified Two-Tiered Testing Algorithm (MTTT): Algorithm and Reporting Language (For Best Resolution, Print 11x17)
  

• Arbovirus testing in Public Health Laboratories-2018 Survey Report (2021)
  

• Testing Methods for Eastern Equine Encephalitis (2022)
  

Invasive Vector-borne Dise​ases

Dengue virus, chikungunya virus and Zika vi​rus have become public health concerns in the US. Though these viruses are predominantly seen in travelers returning to the US, some local tra​nsmission of dengue​ and chikungunya has occurred in the US, and health authorities continue to monitor the status of the Zika virus closely. Many public health laboratories maintain capability to test​ for one or more of these and other invasive​ VBDs. 

• Dengue: State and local public health laboratories diagnose suspected dengue cases through virus isolation, serological tests or molecular methods.
  

• Zika: ​Following the Zika virus response, APHL published a book highlighting the experiences of public health laboratories keeping up with the Zika outbreak and the challenges they faced during the response. 

• Chikungunya: For chikungunya virus protocols visit APHL's Emerging Infectious Disease Protocols (member access only). ​​
  

Vector-borne Diseases Training and Educational Resources​