West Nile Virus

Due to the growing number of patients with Lyme and other tick borne diseases testing positive for West Nile Virus (WNV), and the discovery of WNV in ticks, it is now listed here as a possible tick borne disease and something to be considered.


Fever, headache, body aches, joint pains, vomiting, diarrhea, or rash. Fatigue and weakness can last for weeks or months.

Some develop a more severe illness that can affect the central nervous system- such as encephalitis (inflammation of the brain) or meningitis (inflammation of the membranes that surround the brain and spinal cord). This can be accompanied by high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis.

Recovery from severe illness might take several weeks or months. Some effects to the central nervous system might be permanent. About 1 out of 10 people who develop severe illness affecting the central nervous system die. Source- CDC


As with Lyme and other tick borne disease tests, the tests for WNV can be negative even if infected.

According to the CDC, if serum is collected within 8 days of illness onset, the absence of detectable virus-specific IgM does not rule out the diagnosis of WNV infection, and the test may need to be repeated on a later sample.

Viral cultures and tests to detect viral RNA (e.g., reverse transcriptase-polymerase chain reaction [RT-PCR]) can be performed on serum, CSF, and tissue specimens that are collected early in the course of illness and, if results are positive, can confirm an infection. Immunohistochemistry (IHC) can detect WNV antigen in formalin-fixed tissue.

Negative results do not rule out WNV infection.


There is no specific treatment for WNV disease; clinical management is supportive.

Patients with severe meningeal symptoms often require pain control for headaches and antiemetic therapy and rehydration for associated nausea and vomiting.

Patients with encephalitis require close monitoring for the development of elevated intracranial pressure and seizures.

Patients with encephalitis or poliomyelitis should be monitored for inability to protect their airway. Acute neuromuscular respiratory failure may develop rapidly and prolonged ventilatory support may be required.

Source- CDC

West Nile Virus In Ticks

"WNV infection was detected in mosquitoes (Culex, and Aedes) and ticks (Argas reflexus hermanni)."

Link- https://www.ncbi.nlm.nih.gov/pubmed/30695031

"Interestingly, WNV infection was observed in ticks Argas reflexus hermannii. Previous studies from other regions of WHO also detected WNV RNA in ticks R. turanicus and mites D. gallinae and O. sylvarum."

Link- https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0007081

"Infected O. moubata ticks transmitted the virus to rodent hosts, albeit at a low level. Moreover, the virus was nonsystemically transmitted between infected and uninfected O. moubata ticks co-fed upon uninfected hosts. Although ticks are unlikely to play a major role in WNV transmission, our findings suggest that some species have the potential to act as reservoirs for the virus."

Link- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3323096/

Mumcuoglu KY, Banet-Noach C, Malkinson M, Shalom U, Galun R. Argasid ticks as possible vectors of West Nile virus in Israel. Vector-Borne Zoonotic Dis (Larchmont, NY). 2005;5(1):65–71. Epub 2005/04/09. pmid:15815151.

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CDC & IDSA Do Not List West Nile Virus

As Possibly Being Transmitted By Ticks,

Nor Are They Studying It.

It appears, like with other tick borne diseases,

It isn't even on their radar.


Transmission Cycle

West Nile Virus Transmission Cycle Cdc-pdf[PDF – 1 page]

West Nile virus is most commonly spread to people by the bite of an infected mosquito.

Mosquitoes become infected when they feed on infected birds. Infected mosquitoes then spread West Nile virus to people and other animals by biting them.

In a very small number of cases, West Nile virus has been spread through:

Exposure in a laboratory setting

Blood transfusion and organ donation

Mother to baby, during pregnancy, delivery, or breast feeding

West Nile virus is not spread:

Through coughing, sneezing, or touching

By touching live animals

From handling live or dead infected birds. Avoid bare-handed contact when handling any dead animal. If you are disposing of a dead bird, use gloves or double plastic bags to place the carcass in a garbage can.

Through eating infected birds or animals. Always follow instructions for fully cooking meat from either birds or mammals.

Link- https://www.cdc.gov/westnile/transmission/index.html

Last Update- February 2019

Lucy Barnes