Oral vaccination reduces the incidence of tuberculosis in free-living brushtail possums

Abstract

Bovine tuberculosis (Tb) caused by Mycobacterium bovis has proved refractory to eradication from domestic livestock in countries with wildlife disease reservoirs. Vaccination of wild hosts offers a way of controlling Tb in livestock without wildlife culling. This study was conducted in a Tb-endemic region of New Zealand, where the introduced Australian brushtail possum (Trichosurus vulpecula) is the main wildlife reservoir of Tb. Possums were trapped and vaccinated using a prototype oraldelivery system to deliver the Tb vaccine bacille Calmette -Guerin. Vaccinated and control possums were matched according to age, sex and location, re-trapped bimonthly and assessed for Tb status by palpation and lesion aspiration; the site was depopulated after 2 years and post-mortem examinations were conducted to further identify clinical Tb cases and subclinical infection. Significantly fewer culture-confirmed Tb cases were recorded in vaccinated possums (1/51) compared with control animals (12/71); the transition probability from susceptible to infected was significantly reduced in both males and females by vaccination. Vaccine efficacy was estimated at 95 per cent (87-100%) for females and 96 per cent (82-99%) for males. Hence, this trial demonstrates that orally delivered live bacterial vaccines can significantly protect wildlife against natural disease exposure, indicating that wildlife vaccination, along with existing control methods, could be used to eradicate Tb from domestic animals.

Host density thresholds and disease control for fisheries and aquaculture

“…Vaccination can also be effective in controlling density-independent transmission by reducing the proportion of infectious contacts with susceptible hosts. These considerations underlie the design and motivation for vaccination strategies for many diseases such as rabies in African domestic dogs (Hampson et al 2009), the endangered Ethiopian wolf (Haydon et al 2006), or the red fox in Europe (Suppo et al 2000), or bovine tuberculosis from possum populations in New Zealand (Tompkins et al 2009). …”

Evaluating seasonal bait delivery to badgers using rhodamine B

“…The deployment of baits containing vaccine has been the principal method for the successful management of rabies in foxes throughout much of Western and Central Europe (Flamand et al 1992;Stöhr and Meslin 1996;Cliquet and Aubert 2004). More recently, oral vaccination has been employed in field studies of the management of bTB in brushtail possums (Trichosurus vulpecula) (Tompkins et al 2009). In the UK and Ireland, much current research effort has been focused on the development of a palatable bait for the delivery of live BCG (Bacille Calmette Guerin) to badgers and a means of deploying it to a high (but as yet undefined) proportion of the badger population.…”

Postexposure Subunit Vaccination against Chronic Enteric Mycobacterial Infection in a Natural Host

“…Similarities between bovine and human mycobacterial infections relate to infectious dose, pathology, prolonged latency periods, clinical wasting disease, and immune responses (13)(14)(15). Preexposure vaccines have been evaluated in cattle with experimental tuberculosis infection (16)(17)(18). But for evaluation of postexposure vaccines, no experimental model is available, and the use of naturally infected cattle is limited because the time of exposure cannot reliably be assessed.…”