Hogan, a former head of PR for drugs giant Pfizer in South Africa, said she had left 'by mutual agreement'.
She told PRWeek she was now freelancing for the World Health Organisation's working party on Parkinson's disease.
Hogan is specifically working to raise awareness of Parkinson's in South Africa. She conceded this was a 'challenge' in a country where Aids most captured media attention.
Hogan joined Jango last autumn, having freelanced for Sante Communications (PRWeek, 10 September 2004). She said she was also thinking about freelance work for Johannesburg-based agency Meropa Communications.
Jango is planning to replace Hogan.