The animals you own are one of my favorite species to work with. One of the saddest things I see is deaths related to preventable diseases; therefore I wanted to share with you my experience with Eastern Equine Encephalitis (EEE) in alpacas.

EEE is a virus transmitted by mosquito bites. It is maintained in the environment between birds and mosquitoes, but it can effect often with deadly consequences- humans, alpacas, horses and other species. It was not recognized in the alpaca until recently. The disease causes swelling of the brain leading to neurological symptoms including mental dullness, stargazing (head and neck bent backward and looking upward), seizures, and high death rate. This disease can only be spread from mosquito bites; alpacas CANNOT spread it amongst themselves or to humans. It is a sporadic disease that may affect only a few animals in a given area a year, but when it strikes it has deadly consequences. In New England the highest risk time for contracting EEE are the months of August, September, and early October until a killing frost.

In September of 2005 the practice I worked at diagnosed EEE post mortally in 3 alpacas and EEE was strongly suspected in a fourth case. That year there were also reported EEE alpaca deaths in ME, MA, and NY. Despite efforts to try to get the word out that alpacas are susceptible to EEE, I have been disappointed by further EEE alpaca deaths in the communities around were I practice and have received reports of other mortalities along the East Coast.

After the deaths in 2005, NEAOBA members got together to fund a study to see if vaccination with an equine EEE vaccine (Encevac EEE (and WEE), by Intervet) would produce an antibody titer. This study was successful in showing that the equine vaccine did not appear to be detrimental to any of the study alpacas but did produce EEE antibodies. Although it was not possible to take the second step; in which the vaccinated animals would be exposed to EEE to prove that the antibody titers were enough to prevent them from becoming sick (or dying) from EEE, I have developed a vaccine protocol based on our study’s findings and am proud to say that so far I have not lost another alpaca to EEE in my vaccinated herds.

Although one of the alpacas lost in 2005 was a yearling, most of the affected animals were less than one month old. Therefore we are relying on vaccinated mothers to pass along immunity in the colostrum. Crias born just before or during the high risk months (i.e. July September) will not have enough time to develop their own immunity after vaccination.

Although I cannot legally advise any farms without examining the alpacas in person, I have included the vaccine protocol that I use on the farms I visit. If you wish to adopt something similar on your own farm this is not without risk (as you see below it includes vaccinating pregnant animals). You should discuss vaccination with your veterinarian. I will accept no liability for those who do not consult their own veterinary professional.

My vaccine protocol is as follows: EEE tends to peak in late August and September so I try to time my injections to have immunity boostered prior to the season. Peak protection will not be reached until 2-3 weeks after the 3rd vaccination.

In a naive herd (Year One): Start in March with EEE vaccination monthly for 3 months including pregnant mothers (yes, this has some risks associated with it and should be discussed with your veterinarian prior to starting the program). I gave the vaccinations mid-pregnancy, and fortunately have not seen any abortions or cria malformations related to vaccination.

Crias born to vaccinated mothers will be protected by maternal antibodies for about 3 months after birth. After that they need to be given their own 3-vaccine series. Crias born in late September or after will not have time to complete the series before frost when the risk is over for animals in New Hampshire so we wait till the following spring to give them their 3-vaccine series.

After the first year of the 3 vaccine series, a single annual booster vaccine is given in May or June, trying to avoid the last month of gestation for pregnant animals.

The vaccine I currently use is Encevac-T (Intervet EEE, WEE, T or EWT). This is the same brand that was used in our vaccination study, but with tetanus (the product is no longer made without tetanus). This is the same T as in CDT. I still recommend protecting against Clostridium C&D, and occasionally I can find this product without tetanus, but if not I simply avoid giving CDT in the same month as EWT and have had no problems with reactions to date.

In general, you can vaccinate a small herd (even year one) for less than the price of a single cria. That, combined with the low risk of side effects, and the potential costs if you do have a sick cria, means that it makes economical sense to protect your herd.

Sincerely, Amy Bright, DVM Andes Veterinary Service Inc. Candia, NH

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