G. ornativa is confined to the western drier areas of the country, while G. burkei is to be found around the Gauteng area and G. aspera is seen chiefly in the eastern Highveld of S.A.
• Much-branched woody shrublets 10-20 cm high.
• The leaves are usually narrow, ribbon-like with a rough texture.
• The yellow flowers are grouped in compact heads in the leaf-axils or at the ends of the branches.
The active principles from these plants are all sesquiterpene lactones (C15-compounds) and a series of these have been isolated, the most important being geigerin, geigerinin and vermeerin.
• Striated muscle degeneration and necrosis take place and it affects especially skeletal and oesophageal musculature.
• There is a lack of tonus or peristaltic activity of the oesophagus and stasis of the rumen.
• Consequently eructation and regurgitation may be influenced, resulting in mechanical interference with these functions which is then interpreted as vomition.
• Merino and Karakul sheep are more susceptible than Dorper sheep which in turn are more susceptible than Persian and Baster sheep.
• Four forms are seen: stiff, paralytic, bloat and vomiting forms (vermeersiekte), as well as combinations of these.
• In general it takes three weeks for this condition to develop in Geigeria ornativa infested veld.
• Weakness and anorexia are seen first and animals tire easily when they are herded with the rest of the flock (lag behind).
• Stiffness occurs and the animals walk with difficulty which is followed by paralysis.
• “Vomition” characterized by the regurgitation of ingesta through the mouth and nose,may be seen at any stage or may not be present at all.
• This varies from light contamination of the nose and mouth to an outspoken condition.
Cattle and goats: The stiff and paralytic forms are seen.
Springbok: Occasionally affected.
Any combination of the above symptoms is possible.
Consequences of regurgitation:
1. Foreign body pneumonia is the usual cause of death
2. Mortality due to choking and asphyxiation.
• Usually rather negative.
• Only signs of foreign body pneumonia, especially in the apical and cardiac lobes of the lungs, may be seen.In pronounced cases necrosis of the oesophagus may result in connective tissue deposition and severe dilation which may be so severe that one encounters the so-called mega-oesophagus.
• Oesophageal and skeletal musculature show vacuolisation and hyalinization due to degeneration of the myofibrills.
• Foci of myocardial degeneration and necrosis, particularly in the inner third of the left ventricular wall and throughout the interventricular septum
• Non-specific lesions in the CNS may be present.