Search

This study aimed to investigate the serological characteristics of Ebola virus (EBOV) infection during the late phase of the Ebola outbreak in Sierra Leone. In total, 877 blood samples from 694 suspected Ebola virus disease (EVD) cases assessed from March to December 2015, were analyzed via real-time reverse transcription polymerase chain reaction (RT-PCR) for viral RNA and enzyme-linked immunosorbent assay (ELISA) and Luminex to detect antibodies against EBOV. Viral load and EBOV-specific IgM/IgG titers displayed a declining trend during March to December 2015. Viral RNA load decreased rapidly at earlier stages after disease onset, while EBOV-specific IgM and IgG still persisted in 58.1% (18/31) and 93.5% (29/31) of the confirmed EVD patients and in 3.8% (25/663) and 17.8% (118/663) of the RNA-negative suspected patients in the later phase, respectively. Dynamic analysis of longitudinally collected samples from eight EVD patients revealed typically reversed trends of declining viral load and increasing IgM and/or IgG titers in response to the EBOV infection. The present results indicate that certain populations of Sierra Leone developed immunity to an EBOV infection in the late phase of the outbreak, providing novel insights into the risk assessment of EBOV infections among human populations.

During the 2014 Ebola virus disease (EVD) outbreak, a real-time quantitative polymerase chain reaction was established to detect and identify the Zaire Ebola virus. We describe the use of this assay to screen 315 clinical samples from EVD suspected person in Sierra Leone. The detection rate in blood samples was 77.81% (207/266), and there were relatively higher detection rate (79.32% and 81.42%, respectively) during the first two weeks after onset of symptoms. In the two weeks that followed, the detection rate declined to 66.67% and 25.00%, respectively. There was the highest virus load at the first week and then decreased. The detection rate in swab samples was 89.79% (44/49). This may be benefit from the included patients. 46 of 49 swab samples were collected from died patients. Taken together, the results presented here indicate that the assay specifically and sensitively detects Zaire Ebola virus.