Ken Opalo has an excellent article on drug trafficking in Africa:
The problem of drug trafficking in Africa is not merely a law enforcement concern. Firstly, it is a threat to the development and consolidation of important state institutions, especially the region’s judiciaries and security agencies. In many of the African states that have been cited as important transit destinations for drugs from Latin America and Asia, drug traffickers have managed to infiltrate vital state institutions. Important politicians, members of the judiciary, and key members of the security apparatus – both police and the military – have been their primary targets. As a result, the very institutions that have been charged with policing such illicit activities have been the ones that actively promoted and/or provided protection for drug traffickers. Ineluctably, the large amounts of drug money up for grabs have caused splits among ruling elites, sometimes resulting in bloody conflict, as has been the case in Guinea-Bissau since early 2009.
Apart from the political and security problems that come with drugs trafficking, another particularly worrying trend is the adoption and usage of cocaine and heroine by people in communities along the trafficking routes. From a UN report:
Drug use appears to be spilling over into countries lying on trafficking routes, such as in West and Central Africa, which is witnessing increasing numbers of cocaine users. The increasing use of heroin and drug injecting is also emerging as an alarming trend, particularly in Eastern Africa.