Dreamcatcher Alpacas
Alpaca health · Infectious diseases

West Nile Virus in Alpacas

Updated 2026-10-02By the Dreamcatcher Alpacas editorial team6 peer-reviewed references
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Urgent — contact your vet today

Early treatment makes a big difference. Don't wait more than a day.

A mosquito-borne virus that occasionally causes neurological disease in camelids.

Category
Infectious diseases
Urgency
Urgent

Signs & symptoms

  • Weakness, incoordination
  • Muscle tremors
  • Head tilt
  • Recumbency

Related symptom guides: Hind Leg Weakness & Wobbly Walk.

What causes it?

West Nile virus, transmitted from birds by mosquitoes.

Risk factors

  • Summer and early autumn
  • Areas with WNV activity in birds or horses

How vets diagnose it

Blood antibody testing and ruling out other neurological diseases.

Treatment

Supportive vet care; many cases recover.

Do not wait to see if it improves. Camelids hide illness, and by the time signs are obvious the problem is often advanced. Call your veterinarian.

Prevention

  • Mosquito control
  • Discuss vaccination with your vet

Background

West Nile virus (WNV) is a single-stranded RNA virus that causes West Nile fever. It is a member of the family Flaviviridae, from the genus Orthoflavivirus, which also contains the Zika virus, dengue virus, and yellow fever virus. The virus is primarily transmitted by mosquitoes, mostly species of Culex. The primary hosts of WNV are birds, so that the virus remains within a "bird–mosquito–bird" transmission cycle. The virus is genetically related to the Japanese encephalitis family of viruses. Humans and horses both exhibit disease symptoms from the virus, and symptoms rarely occur in other animals.From Wikipedia — “West Nile virus”, licensed under CC BY-SA 4.0.

Research & references

PubMed lists 3,541 peer-reviewed papers on this topic in camelids. The most relevant include:

  1. Camelid cardiology. Margiocco ML, Scansen BA, Bonagura JD The Veterinary clinics of North America. Food animal practice, 2009. PubMed 19460649 · DOI · cited 20×
  2. Camelid wellness. Bennett MM, Richards NL The veterinary clinics of North America. Exotic animal practice, 2015. PubMed 25902272 · DOI · cited 3×
  3. Update. Llama nutrition. Johnson LW The Veterinary clinics of North America. Food animal practice, 1994. PubMed 7953953 · DOI · cited 13×
  4. Middle East respiratory syndrome coronavirus infection in camelids. Te N, Ciurkiewicz M, van den Brand JMA et al. Veterinary pathology, 2022. PubMed 35001773 · DOI · cited 9×
  5. Encephalomyocarditis virus infection in alpacas. O'Connor TW, Finlaison DS, Manning LK et al. Australian veterinary journal, 2020. PubMed 32794196 · DOI · cited 2×
  6. Cladophialophora encephalitis in an alpaca. Balducci JJ, Barber RM, McHale BJ et al. The Canadian veterinary journal = La revue veterinaire canadienne, 2020. PubMed 32020931 · cited 1×

Frequently asked questions

What is west Nile Virus in alpacas?
A mosquito-borne virus that occasionally causes neurological disease in camelids.
What are the signs of west Nile Virus?
Weakness, incoordination, muscle tremors, head tilt and recumbency.
How do you prevent west Nile Virus?
Mosquito control. Discuss vaccination with your vet.
Is west Nile Virus an emergency?
Urgent — contact your vet today. Early treatment makes a big difference. Don't wait more than a day.

This page is educational and does not replace advice from a veterinarian who has examined your animals. Camelid medicine uses many drugs “extra-label”, so dosing must come from your vet. In an emergency, call your vet first. Read our disclaimer · How we write and review content.