Since early 2014, Ebola has infected about 27,600 people and caused more than 11,200 deaths. And this outbreak is not over. To put this in perspective, the largest outbreak ever recorded previously was 425 cases in Uganda.

Gabrielle Fitzgerald, director of The Paul G. Allen Ebola Program, talking with staff at the national 115 Call Center in Conakry, Guinea.

Last month, I visited Sierra Leone and Guinea, and continue to be impressed at how hard people are working to try to bring the outbreak under control. Six realities stand out that remind me how far we’ve come and how far we still have to go to reach zero Ebola cases.

There is still an Ebola epidemic in West Africa — Just because the number of new Ebola cases each month is dramatically lower than at the height of the epidemic last year doesn’t mean the outbreak is over. Last week, there were 30 new cases, which is the highest we’ve seen in two months. In any other circumstance, 30 new Ebola cases would be a cause for significant alarm. Additionally, many of these cases came through unknown human contact, so we still do not have a grip on how and where the virus is moving.

It’s the time of year when Ebola cases might spike — With the onset of the rainy season this month, Sierra Leone and Guinea will receive up to 55 inches of rain on average per month, through November. This annual deluge washes out roads and diminishes sanitary conditions, making it difficult for people possibly infected with Ebola to travel to health facilities, and for response teams to reach the remote villages where Ebola may arise.