Health officials botched more than 20 Ebola blood tests in January and February which led to the release of at least four positive patients, two of whom later died, Guinea's anti-Ebola coordinator and other health officials told Reuters. 

Five health officials and experts familiar with the incidents said the mistakes occurred at two different treatment centers and resulted as many as 52 botched tests, exposing many others to the virus and revealing weaknesses in Guinea's response to the crisis.

Dr Sakoba Keita, Guinea's anti-Ebola coordinator, confirmed the mistake had occurred but gave lower figures. He said in an emailed response to questions that 23 patients were affected, of whom four tested positive when they were retested and two died.

"This error was detected and the order was immediately given to withdraw the tubes and to find the sick in order to test them again," Keita said.

Health officials, some of whom asked not to be named because they were worried about embarrassing the Guinean government, said the mistakes took place in Coyah, where Cuban medics are supporting a government-run center, and in Conakry, where medical charity Medicins Sans Frontieres runs another center at the Donka hospital complex, when staff placed blood samples in the wrong test tubes, damaging specimens.

Patients were discharged from the centers in western Guinea, one of the biggest remaining Ebola hotspots in the region, after the test results came back negative from the laboratory at Donka, the health officials said.

At least six patients were later found to be Ebola-positive when further tests were carried out, and two of them died, the officials said.

"There were deficiencies from the moment the samples were taken right through to the test results," said one health official in Guinea, who requested anonymity.

The incident involved many actors in the Ebola response in Guinea, where the current outbreak was first confirmed a year ago and officials are scrambling to meet a regional deadline to reduce the number of cases to zero within six weeks.

The worst Ebola outbreak on record has killed nearly 10,000 people across West Africa. Guinea has recorded 2,091 deaths - fewer than in Liberia and Sierra Leone, the other worst-hit nations - and cases have fallen sharply in the past month.

Several officials said the blood test incident pointed to gaps in the country's response.

"It's not that their staff didn't receive training. It's just a question of being rigid and organized and that seems to be hard for Guinea," said a Western health expert who spent months in the country.

TEST TUBE MIX-UP

MSF said it discovered on Feb. 6 that blood samples from 43 patients taken from its Donka center had been placed in tubes containing the blood-thinning drug heparin.

Heparin typically takes the form of an invisible coating inside a tube whereas Ebola tubes are either empty or contain a blood preservative called EDTA. It should have been easy to identify the correct tubes since the set containing heparin have green lids and the ones used for Ebola are red or purple.

"MSF took the incident very seriously and immediately replaced the tubes and opened an investigation," said Rosa Crestani, MSF's emergency program coordinator.

Three of those tested were later discovered to be Ebola positive and recovered, she said. No-one who came in contact with the trio who contracted the disease.

At the Coyah center, Guinea's busiest Ebola facility that is also supported by staff from the African Union, the samples of nine people were accidentally placed in tubes also containing heparin, said another health official.

The official said that after initially being found to be negative, three of the nine later tested positive, of whom two died. No further cases among contacts of the Ebola patients released from Coyah have been identified, he said.

President Alpha Conde hopes to get to zero cases by mid-April as he seeks to lure back mining investment ahead of a presidential vote due later this year.

But Guinea is still battling often violent resistance to its Ebola health campaign. One of the sources said that a similar mix-up had occurred in late 2014. The government did not respond to a question about whether it had happened before.

Guinea has received less financial aid than other Ebola countries, with $266 million in commitments - about half that for Sierra Leone and a third of Liberia's total, according to the U.N. financial tracking service.

France is providing technical support to its former colony but it has not launched a military operation like Britain did for Sierra Leone and the United States did in Liberia.

It was not clear why the mistake was not detected in the Donka laboratory, which tested both sets of samples. The laboratory is run by Guinea and supported by the Institut Pasteur de Dakar – a foundation created in 2009 by a statute signed between Senegal and France's Institut Pasteur.

Dr. Andre Spiegel, director of the Institut Pasteur de Dakar, declined to comment, saying the information was sensitive and confidential. Guinea's Keita said the World Health Organization (WHO) had sent a supervisor to assist the laboratory. The WHO did not respond to a request for comment.

Another Western official in Guinea said partners in a Guinea anti-Ebola drug test were now nervous about extending it to other centers in Guinea such as Coyah.

Dr. Dan Kelly, founder of the Wellbody Alliance providing healthcare in Sierra Leone, said it was not unusual for centers to run out of test tubes but procedures existed.

"Stock outs happen. What you are supposed to do is wait for the right colored tubes to arrive," he said.