Bovine Tuberculosis Outreach Day hosted by the Faculty of Veterinary Science, University of Pretoria

Bovine Tuberculosis Day highlights some alarming facts about the disease and the need for more research and adapted control strategies.

A collaborative team effort is needed to counter the increasing danger of bovine tuberculosis (BTB) in wildlife evident in the continuous spreading of the disease to wildlife on unrelated properties in different parts of South Africa. That was the core message at a Bovine Tuberculosis Outreach Day hosted by the Faculty on 2 March 2015, spearheaded by Prof Anita Michel of the Department of Veterinary Tropical Diseases of the Faculty of Veterinary Science.

According to Prof Michel the unique and well-attended day was organised to share the knowledge gained from research done on the disease in the past two years, and the evidence that TB is spreading in wildlife at an alarming and increasing rate. The day was also organised to convey the message that there is an existing formal Study Group on Tuberculosis in Wildlife that is doing research on the disease in South Africa and that they also want to collaborate more effectively with, among others, game farmers. Prof Michel emphasised that a team effort is needed between academia, Government, private game farmers, and other role players.

This was reiterated by Dr Lin-Mari de Klerk-Lorist of the Kruger National Park in her presentation at the event, which focused on the current status of BTB control in wildlife in South Africa. Dr de Klerk-Lorist’s presentation highlighted some alarming facts about the current lack of measures and strategies pertaining to wildlife for the control of BTB, one of which is the fact that currently there are only reasonably effective strategies, screening and diagnostic testing in place for buffaloes. This is despite the fact that research shows that many mammalian species are susceptible to the disease including meerkats and cheetahs.

Prof Michel says that, the current situation creates a whole new challenge and improved measures have to be implemented to identify which other species are also high-risk carriers of the disease and that validated diagnostics be developed for these species. Work done on buffaloes is certainly the beginning but definitely not the end, Prof Michel says. While this is a chronic, highly contagious disease, it can take years to find out that transmission between species has taken place and that new properties have been infected. Although the methods of transmission of BTB in livestock, specifically between cattle, is better known, a lot more information and research are needed to determine the nature of the interaction between livestock and wildlife as it affects the transmission of the disease between the various species.

Looking at all risk-factors, the lack of information and of funding, what is the extent of this problem then? Prof Nick Kriek, emeritus professor and former Dean of the Faculty who is still employed by the Section of Pathology in the Faculty and who was also one of the speakers at the outreach day, paints quite a gloomy picture.
According to Prof Kriek there is a lack of information about the extent to which cattle are infected with BTB in the country. From as far back as 2008 data to indicate the level of infection of herds or individual hosts are unobtainable from the Government’s veterinary services. The fragmentation of Veterinary Services on Provincial level has had a direct impact on the quality of the current information and quality of the control programmes.

Prof Kriek says that when there is a wildlife maintenance host for TB in a system, the experience is that it is impossible to eradicate TB in cattle. This phenomenon is encountered in countries such as Canada, the United Kingdom, New Zealand, Spain, and the USA. The extent to which infected wildlife act as sources of the infection for cattle in South Africa is unknown.  The situation here may be even more complex as the infection has now been detected in 21 local free-ranging wildlife species. Currently we do not fully understand how the disease is transmitted between infected wildlife at the interface between wildlife and livestock, nor between the various wildlife species. This contributes to the complexity of the issue in that infection in wildlife creates a reservoir(s) that makes the control of TB in cattle very difficult and eradication impossible.

“Until we know what the mechanism of transmission is between cattle and wildlife and vice versa, we cannot effectively control it”, Prof Kriek says. He points out that what we know is that BTB is a chronic and highly contagious disease, and, that in experimental terms, the easiest way to transmit it is by inhaling infected droplets arising from infected animals. Infection can be established by inhaling only one bacterium. The mycobacteria can stay alive for up to 12 hours and the droplets in which they occur, can be carried by the wind through, for example, fences. However, according to Prof Kriek the way in which the disease is transmitted is universally largely unknown even after extended ongoing research. The mechanism of transmission can also differ from one region to another. He also warns that although much emphasis is placed on buffalo-carriers in South Africa, it must be emphasised that any one of the 21 infected wildlife species, irrespective of whether they are maintenance hosts or not, can infect other susceptible animals.

To be more successful in identifying the spread and occurrence of the disease the current misconception that wild animals are not acting as reservoirs for TB in South Africa, should also be addressed and high-risk profile analyses would have to be done on a wide scale.  Regular testing and screening would have to be carried out on herds involving all affected species.

Both Prof Kriek and Prof Michel are of the opinion that in order to make any progress in addressing the complexity of the TB problem, increased and focused research is of crucial importance. Wider surveys, more and reliable data, and increased funding for BTB research are of the utmost importance. However, researchers mostly have to rely on outside funding because currently funding from government is limited or non-existent.
According to Prof Michel research should ideally be aligned with government’s mandate to control the disease. At the moment if an external funder donates money for research, the funder’s aims and goals are often not aligned with those of Government. There are also regulatory requirements when research is planned to which researchers must adhere to, i.e. obtaining permits to do the research, and other obligations. In this regard it can take up to 3 months to be issued a permit by Government.

Dr Lin-Mari de Klerk-Lorist pointed out that currently owners of disease-free (based on existing and historical test records) buffaloes have access to an exclusive and lucrative market. If, however, one buffalo in a herd tests positive for TB the value of the animals totalling millions of rand is reduced to a few thousand rand.
As Prof Michel has indicated it is thus important that regular diagnostic testing and screening of wildlife for the presence of BTB are of the utmost importance. In addition, when introducing new wildlife species onto a property, a risk assessment of the animals and property from where they originated must be done to limit the risk of introducing infected animals.

It is clear that developing new strategies, closer cooperation between the various parties, more research, and adequate research funding are necessary if any progress is to be made in understanding and fighting the disease.

Maybe it is time that the approach anew be aligned with the Animal Diseases Act No 35 of 1984, which, right at the beginning, states: “To provide for the control of animal diseases and parasites, for measures to promote animal health, and for matters connected therewith”.  And for the purpose of this Act, it furthermore states that “animal” means “any mammal, bird, fish, reptile or amphibian…”


** Other speakers at the event included Prof Dr Christian Gortazar-Schmidt, Head of the SaBio Research Group, National Wildlife Research Institute (IREC) in Spain, Dr Peter Buss,  Senior Manager: Veterinary Unit, KNP, Dr Donald Sibanda, State Veterinarian at the Mpumalanga Department of Agriculture, Rural Development, Land and Environmental Affairs, Prof Paul van Helden, Director: Centre for Tuberculosis Research at the University of Stellenbosch, Dr Alex Lewis, Wildlife Veterinarian and Dr Alicia Cloete, State Veterinarian.