Now a rhino TB threat
SOUTH Africa’s poaching-beleaguered rhino population could be facing a new hidden risk – tuberculosis.
Animal disease experts at the Medical Research Council and Stellenbosch University say that while there is no “immediate risk” to rhinos from TB, the disease could become a cause for concern if new veterinary restrictions were placed on moving disease-infected rhinos to more secure locations because of poaching.
Writing in a recent academic journal, Professor Michelle Muller, of Stellenbosch University, and fellow researchers said rhinos were already under pressure from horn poaching and habitat loss.
“With a decreasing number of animals, any additional losses, even due to sporadic disease, is a concern for the survival of the species. Many of the remaining wild rhinos live in areas that have endemic bovine TB, as well as being in countries with a high human TB burden.”
Muller said two of the largest rhino reserves, Kruger National Park and Hluhluwe-Imfolozi Park, were also home to TB-carrying buffalo.
“As documented in other wildlife species, TB could establish itself in a rhinoceros population but remain unrecognised for decades, with detrimental implications for wildlife conservation at large, should such animals be moved to uninfected areas or facilities.”
Miller has previously warned that TB develops over a period of months to years and can lead to lower milk production in mothers, a decrease in fertility, loss of body condition, coughing and possibly death.
While there were still large knowledge gaps, it appeared that the disease was exacerbated during drought.
There was also evidence from Hluhluwe-Imfolozi that buffalo infected with bovine TB had a lower population growth rate than normal.
Animal health experts who modelled the possible effects of bovine TB in the lion population in Kruger National Park had predicted a population decline of between 35% and 75% over 50 years.
Regarding TB in rhinos, Muller and her colleagues said very little was known so far about the impact and therefore urged a greater research focus.
“Since TB is a controlled disease, regulatory agencies can impose movement restrictions which would affect potential reintroduction and programmes designed to move rhinos to more secure locations and to maintain genetic diversity.”
There was still a shortage of tools to diagnose TB infections accurately in wild animals.
However, the Animal TB Research Group at Stellenbosch was investigating new bloodbased tests.
“Recently, our group published a novel test for TB in buffaloes. Since little is known about how the rhino immune system responds to disease, our group is planning a study to characterise these responses and develop tools that can be used to determine the risks of infection in these species.”