Notice landed today that this book 'Dirty War: Rhodesia and Chemical Biological Warfare 1975-1980' is due out in April 2017, publihed by Helion Books (UK). From Amazon's summary:
At times in the conflict, the Rhodesians thought that their poisons effort would bring the decisive blow against the guerrillas. For months at a time, the Rhodesian use of CBW accounted for higher casualty rates than conventional weapons. In the end, however, neither CBW use nor conventional battlefield successes could turn the tide.
From the author's bio:
Dr. Glenn Cross currently works for the US Government on WMD issues. Since the early 1990s, he has worked on biological weapons (BW) issues for several U.S. intelligence agencies....He also was a post-doctoral fellow at Georgetown University where he conducted an exhaustive study of the Rhodesian CBW program as an example of a CBW program that had slipped under the radar of most other nations.

In the UK publication is November 2016:

When I was in Zimbabwe in 1985 there was very little known, rumours abounded and the guerillas had their own memories.