Peter Rogers, 11 March 2025 Good morning all. I have a client who has about 14 giraffe on 300 ha. of land. They have lost 4 (mostly younger animals) of them over the last 6 months or so. I was able to do a PM on a very fresh one – this tested negative for Clostridia. They seemed to have a lot of the macroscopic/microscopic lesions one would see with heartwater in cattle. The immuno-histochemistry (IHC) stained tissue came back “very suspicious for heartwater”, as the test is not geared for working on giraffe brain material. Has anybody ever seen heartwater in giraffe please, or maybe any different ideas? Erik Verrynne, [11 Mar 2025 at 09:40:54]: Hi Pete. What are their tick burdens? Roy Bengis, [11 Mar 2025 at 09:47:03]: Hi Pete, giraffe are one of the preferred hosts for Amblyomma and are therefore usually exposed to heartwater at an early age, resulting in endemic stability. What was the body condition like? Tannin issues may be a factor if there is a high browsing pressure. Peter Rogers, [11 Mar 2025 at 09:47:49]: Hi Erik. There were lots of Amblyomma ticks. The body condition is good. Rick Last (pathologist) did not indicate that tannin was a possibility. The bush is very lush and plentiful at the moment. Erik Verrynne, [11 Mar 2025 at 09:51:17]: Thanks Pete. Roy has said what I was aiming at. They are not supposed to be susceptible, but under immune compromised conditions they can be. I am not sure about the habitat, but 14 animals on 300 ha may be a bit tight. Peter Rogers, 11 Mar 2025 Above are the histopathology and IHC results Erik Verrynne, [11 Mar 2025 at 10:04:24]: I was taught as a young vet to avoid any giraffe with excessive tick numbers because they will die on you. I suppose the new cocktails are safer and more forgiving for underlying compromises. I suppose the concept of excessive ticks on giraffe as an indicator for a compromised immune system however still applies. Gary Bauer, [11 Mar 2025 at 12:19:15]: I agree with Roy. Tannins, phenols and cresols increase under high grazing pressure. I had a client who lost 17/28 giraffe on 800ha to this problem. Ulf Tubessing, [11 Mar 2025 at 15:35:07]: I would also put overcrowding of giraffe high up on the list, especially if mostly young ones died. We see this especially where the palatable trees have been browsed heavily. Jacques ODell, 11 March 2025 Morning Pete. It would be very concerning if giraffe die from heartwater. They are likely to have some form of innate resistance (like many other African ungulates) and should ideally develop a good immune response following exposure to high tick burdens. Literature on the topic is scant. Peter Oberem’s paper from several decades ago states that giraffe are subclinically infected or refractory. More recent work show they can be experimentally infected, but this did not cause disease. I have a student doing a review of heartwater in wildlife. It would be great if you can get a fresh carcass to us, then we can do a PM and several brain smears from it. Colleagues, if anyone else has had confirmed cases of heartwater in African wildlife, please let me know via WhatsApp (0828332787) or email (Jacques.odell@up.ac
