Canine Distemper Virus on Welgevonden and the last Lioness

By Phillipa Myram (Assistant Research and Volunteer Coordinator), Greg Canning (Research and Volunteer Coordinator) and Sam Davidson-Phillips (Conservation Officer).

Lions (Panthera leo) are one of the many spectacles of Welgevonden Game Reserve. After their introduction into Welgevonden in early 1998 they became one of the primary reasons visitors flocked to the reserve for a unique bushveld experience throughout the year, where lion together with the abundance of other life that the reserve has to offer can be enjoyed. However, a dark time lay ahead for Welgevonden lions in the summer of 2015/2016.

On December 10 2015 the carcasses of 3 lions, a large male, adult female and a sub-adult male were observed just outside one of the lodges on the reserve. Despite the efforts of a post mortem done at the Onderstepoort Pathology Unit the cause of death was not identified and results of subsequent tests were inconclusive. During an afternoon game drive on December 18 2015, one of the western pride females was observed having a seizure and Canine-Distemper Virus (CDV) was suspected. Seizures are the primary physical neurological symptom of the virus but definitive evidence was required to confirm this. This event marked the beginning of a whirlwind disaster for the lions of Welgevonden.

CDV is a virus that forms part of the Paramyxoviruses family which includes viruses such as measles and mumps. The virus is highly contagious, is spread by close contact through the respiratory tract and causes severe neurological symptoms. In response to the suspicions the recombinant vaccine for CDV was sought by reserve management and their advisors, however it is only manufactured in the USA, there was none in stock in SA and it needed to be imported –  the wait commenced. The plan was to, at least, vaccinate all the surviving, and seemingly uninfected, members of the southern pride, totalling seven individuals. For the western pride it was too late as following the discovery of the 3 carcasses, the rest of the pride began showing symptoms and succumbed shortly thereafter. It was possible to confirm that the cause of death was due to CDV and the isolation of the specific strain of the virus could be initiated. During the entire process it became apparent that although there was a large amount of knowledge of CDV in domestic animals the scientific knowledge pertaining to wildlife, including lions, was limited. As a reserve Welgevonden held a mini workshop with all the local experts in the various related fields in an attempt to try and expand the knowledge and identify areas of concern and stimulate research into CDV in wildlife.

However, December 26 2015 brought about the next chapter of the nightmare: the first seizures observed in one of the southern pride’s lionesses. The reserves research team stayed with her throughout the ordeal: monitoring, videoing and keeping record of everything that happened to her. This form of data collection was indeed “a tough day in the office”, the team took comfort in the knowledge that this information is invaluable for research and veterinary science given the violent nature of CDV in Welgevonden lions. The post mortem and samples taken from this animal further contributed to the understanding of the disease in lions and the isolation of the strain of CDV responsible.

Sadly, December 28 2016 saw the death of the lioness in the southern pride, leaving behind her 4 cubs. Being too young to fend for themselves, and fearing they too had been exposed to the virus, they were all captured and moved to the predator boma. Blood samples collected during capture were being analysed to determine if the youngsters had the virus – but more bad news came as one of the cubs started showing symptoms and died and the remaining cubs tested positive for CDV and to prevent the anticipated suffering were euthanised.

One lioness remained on Welgevonden. Her condition was uncertain and it was not known if she had been exposed to and infected by the virus. After weeks of tracking her, and her continual evasion of capture, she was finally caught on February 8 2016 and placed in the predator boma for, testing, monitoring and vaccination.

 

The last lioness initially tested negative to CDV however her white blood cell activity gave evidence of exposure to the virus. Twenty-four hour monitoring ensued with management waiting for the neurological symptoms to show before any action was taken. It must be noted that visual symptoms can often go undetected before neurological symptoms present themselves which makes CDV difficult to diagnose without the correct clinical and histological examination. Therefore, in the following weeks, a rigorous screening regime commenced, including collection and testing of bladder tissue cells, saliva, blood and cerebrospinal fluid, all of which indicated she was virus free and was probably never exposed to the virus during the infectious phase despite being in contact with other lions! The lioness was subsequently vaccinated, a subject of further monitoring and after further testing she was declared CDV free and released from the boma in April 2016.

The introduction of new lions on Welgevonden has been highly anticipated event for WGR’s management, members and lodge staff. June 3 2016 finally saw the arrival of WGR’s two new lionesses; the two year old sisters of Kalahari origin, from Tswalu Game Reserve. The plan was that they would form the first new pride on WGR after bonding with a four year old male lion from Tembe Elephant Park, who arrived June 25 2016. Completely unexpectedly, the male escaped from the predator boma the following day! Upon following up on the escapee, he was eventually seen when he joined the lone female from the original Southern pride. All 4 lions currently on the reserve are doing well. The Kalahari females are still in the predator boma for the remainder of their quarantine period and the male has been allowed to roam the reserve a little earlier than expected, to minimise stress to the animal.

And the last lioness? She has been observed mating with the escapee artist early in July and the pair spent about a week together before parting ways. The male has been seen and heard on numerous occasions as he appears to be determining and establishing the boundaries of his territory. He is in for a small shock when the next male is introduced in the near future. A light at the end of the tunnel for Welgevonden and a happy ending to the lion saga…

Photos by Pip Myram & Sam Davidson-Phillips.