The decision by the government of Uganda to introduce a fee for voluntary tests for Covid-19 threatens to disrupt travel and the resumption of tourism, as well as trade.
It will even affect the return of Ugandan citizens from abroad.
On Sunday evening, the government issued a directive requiring agencies to charge $65 (£50) per test.
It affects cross-border truck drivers, visitors to the country and Ugandans who go home.
Organisations that plan to test their staff and individuals, who want to know if they have contracted the virus, will also have to pay.
The government in Kampala says the fee will contribute to the cost of managing the pandemic. So far, 350,000 people have been tested, revealing about 2,900 positive cases and at least 30 deaths.
People who have developed symptoms, or have been in contact with someone who has contracted Covid-19, will not have to pay.
It is feared the charge may undermine efforts to contain the virus, by discouraging people from getting tested.
It could also increase the cost of imported goods as truck drivers have to pay, as do any potential tourists.