The biggest challenge in controlling any epidemic is separating those infected from those that are not. This breaks the cycle of transmission.
In the case of Ebola, this is especially difficult. First, the symptoms of Ebola are not specific. Fever, weakness, and headaches could be anything from the flu to malaria. But once a person has symptoms, they are infectious to others. So putting a malaria patient next to an Ebola patient while waiting for a diagnosis is a bad idea and can accelerate transmission.
The second challenge is that blood samples are generally required to make the diagnosis. Blood is highly infectious, and drawing blood samples can put health workers in danger. Careless infections and deaths among the short supply of health workers has been happening far too often.
Finally, there is no easy way to make a laboratory diagnosis of Ebola. The ‘gold-standard’ is something called polymerase chain reaction (PCR) – which is a technique to detect small amounts of viral particles. It requires large expensive machines, clean water and electricity, special ventilation and infection prevention equipment. Also, it is slow. A single test can take several hours to process. PCR is currently used in all Ebola affected countries.
There are currently four laboratories in Sierra Leone with the ability to conduct PCR testing. All are supported by partner governments – including a ‘mobile laboratory’ from the Chinese government.
Despite these efforts, the country is only able to perform 150 tests per day in total – just a fraction of what is needed. The transport of specimens to these labs, and the reporting of results also takes time. In the best of cases, several days are needed between being tested and receiving a result. These days are an eternity for an Ebola patient. While efforts are underway to expand this capacity, it could be too little too late.
However, there is some hope. A range of new ‘rapid tests’ are currently under development – where a blood sample from a finger poke could provide a diagnosis in minutes. These look like pregnancy tests and have been used successfully to diagnose HIV.
Several promising tests are in development. Success in these efforts could be a game changer. It would be possible to conduct testing at the household level, and allow us to separate patients with malaria and other causes of fever from Ebola at the earliest stage.
As a global community, it is critical that we bring our full scientific and financial resources to bear to push this process forward.
Paul Pronyk is an infectious disease and public health physician. He has been living and working in sub-Saharan Africa for 15 years – focusing on issues of HIV/AIDS, tuberculosis, maternal-child health, and health systems development. He is currently a Senior Health Specialist with UNICEF headquarters, and has been seconded to Sierra Leone to assist with the Ebola response.