Related Rule
Practice Relating to Rule 73. Biological Weapons
Cameroon’s Instructor’s Manual (1992) states, on the issue of biological and bacteriological weapons: “The restrictions here are clear. It is prohibited to use such weapons against enemy combatants as well as against civilian populations.” It also calls for the “total destruction of the existing stockpile”. 
Cameroon, Droit international humanitaire et droit de la guerre, Manuel de l’instructeur en vigueur dans les Forces Armées, Présidence de la République, Ministère de la Défense, Etat-major des Armées, Troisième Division, Edition 1992, p. 124, § 441.
Cameroon’s Instructor’s Manual (2006) states:
Biological weapons
The World Health Organization defines biological agents as “those which achieve their effects through their capacity to multiply in the attacked organism, designed to be used in case of war to cause the death or illness of human beings, animals or plants.”
The oldest text here is the Geneva Protocol of 17 June 1925 which prohibits the use in war of asphyxiating, poisonous and other gases and of bacteriological methods [1925 Geneva Gas Protocol]. It was complemented by the London Convention of 10 April 1972 on the prohibition of the development, production and stockpiling of bacteriological (biological) weapons or toxin weapons and on their destruction [1972 Biological Weapons Convention].
This convention stipulates general restrictions related to the prohibition of the use of such weapons against enemy combatants and civilian populations. States must destroy or divert to peaceful purposes their existing stockpiles. 
Cameroon, Droit des conflits armés et droit international humanitaire, Manuel de l’instructeur en vigueur dans les forces de défense, Ministère de la Défense, Présidence de la République, Etat-major des Armées, 2006, p. 272, § 631.