Nairobi, Aug. 5 -- When Robert Okubo travelled to Washington, D.C., more than two decades ago, he had no intention of becoming a cleaning entrepreneur.

He was a travel agent then, determined to promote the Kenyan tourism industry after successfully organising domestic travel packages. His next ambition was to break into the international market.

But some global events changed his plans. While in the United States, Mr Okubo says East Africa was hit by a travel ban following an Al-Shabaab attack in Mombasa, leaving him stranded and needing an alternative source of income.

"I found myself stuck in the US and I needed to make some money. One of my Kenyan friends connected me to a company that does cleaning. I took it as a part-time job but...