What does it take to test an Ebola case?

When someone is suspected to have Ebola, they are first isolated based on their symptoms, and a blood sample is drawn from them for testing.

This should be done within a short time to avoid any further local transmission. Their sample does not go to just any laboratory, but specific labs designed for such tests.

We speak to Dr Ahmed Kalebi, a consultant pathologist who explains how an Ebola test is done. 

What happens during an Ebola sample collection?

It is collected by a specialist donned in a full hazmat’s and with full biosafety level 3 to 4 protection. A biosafety level 3 or 4 protection will ensure that any sample that they handle must never get into the environment. When they come to collect the sample, they collect it and immediately put it into a sealed container that is tamper-proof. This container must not break or spill.

Once it gets into the lab, it's only opened inside a facility with what we call negative pressure. Such labs use negative pressure to ensure that no air will go out, should there be an accident and the sample spills. The people who handle samples like that, once they are done with everything, they destroy everything used through incineration.

How is the actual testing done?

Once the sample is collected. The sample is preferably handled inside a Biosafety level 4 laboratory. The most important test for Ebola is called the reverse transcription polymerase chain reaction (RT-PCR).

How does this work?

We have two types of viruses, the deoxyribonucleic acid (DNA) and the ribonucleic acid (RNA) type. Ebola, like the HIV, is an RNA virus. In order to test an RNA virus like Ebola, it has to be converted to DNA. This conversion is called the reverse transcription polymerase chain reaction. It is converted because measuring an RNA virus is difficult, it is easier to measure a DNA virus and quantify it.

Once the test is done, it confirms the genetic material of Ebola as well as the exact species. We have three types so far; the Zaire Ebola virus, Bundibugyo Ebola virus and the Sudan Ebola virus.

Is that the only test?

We have another test called the Rapid Antigen Test, which is mostly used for screening. It is not very accurate but it has been used in some countries that had Ebola outbreaks in West Africa. We don’t have a Rapid Antigen Test for Bundibugyo so far. The other test is called the enzyme linked immunosorbent assay (ELISA) test, which looks for the antibody.

This means that if anyone has ever been infected, an ELISA test can fish that out. The problem with that is that it does not say whether the person is actively infected or not. WHO says that diagnosis must be made using the RT-PCR. These tests are done with dedicated personnel and equipment.

What is the turnaround time for the Ebola Test? 

It should take about 6 hours. After the testing has been done, the sample is stored but everything else is destroyed. 

Why are biosafety level 4 labs fully secured?

It is because nothing has to come out of the biosafety laboratory. It is manned by security personnel 24/7. One of the conditions for having such a laboratory is that it has to be fully contained and secure. It has access control because of risks of people using it as a biological weapon. 

Should we have a surge in local transmissions, can our existing laboratories handle?

We won't manage. We don’t have capacity to handle a surge in this country. When we start having local transmissions, then we may have a problem.

We have capacity to run about 1000 tests, based on the kits that are openly available. 1000 is nothing in the case of Ebola should we have a community surge. The government will have to procure more kits.

How can we transform our laboratories to strengthen preparedness?

We need to increase our biosafety level 4 labs and make sure that they are strategically located. You want to minimize movement of this dangerous sample. If someone has a sample from Wajir, it shouldn't come all the way to Nairobi. That delays diagnosis.

Remember, any delay in diagnosis means you may not efficiently be able to do contact tracing of the infected people. In such circumstances, speed is of the essence

In Kenya’s scenario, how is an Ebola sample transported?

There are specialised units that transports an Ebola sample. It is usually in a container that has about triple layers, that are shock proof and tamper proof. If that vehicle had an accident, there will be no leakage. 

What's the sample like?

It is a blood sample. Ebola is a virus that infects immune cells. They are found in the blood and the tissues. These cells are found all over the body and can infect the blood vessels.

The symptoms usually come because of what Ebola infects. For dead bodies, they can take a swab from the mouth, or sometimes, blood. 

What opportunities do we have in terms of automation and using AI for testing?

It's already there. The machines that we use for Ebola testing have options for automation. Once you get the results, you can use AI for interpretation of genetic sequencing. You can use testing data to make certain decisions based on the spread of the diseases' patterns.

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