How does a disease outbreak start? It’s a simple question that doesn’t have a simple answer. Pathogens that cause infectious diseases can remain inactive, safely cocooned in an animal or environmental reservoir, until the conditions are ideal for emergence and rapid spread. Ongoing research in the Allen School illustrates our efforts to find answers to this critical question. The plague is one of the oldest recorded epidemic diseases and was responsible for the Black Death, which reduced Europe’s population by half in the mid-1300s. Today the plague still remains a serious public health threat in endemic regions–those where the disease occurs with some regularity– globally and here in the United States. From April to August 2015, six U.S. states, predominately in the southwest, reported cases of the human plague. Where the responsible pathogen, Yersinia pestis, “hides” between outbreaks is unknown. Recent research by Allen School professor Dr. Viveka Vadyvaloo showed that pestis can infect amoeba, which are single-cell organisms that can live in the soil. Her findings are critical because plague foci are associated with specific soil types. In this scenario, the plague bacterium remains silently inside the amoeba in rodent burrows and then emerges to infect resident rodents and then humans. Understanding what factors trigger emergence can allow targeted surveillance for future outbreaks before they happen. Targeted surveillance is already being used successfully for Rift Valley fever, a highly fatal viral disease of humans and livestock. Similar to the plague, Rift occurs episodically and is linked to climatic changes that favor its mosquito-borne transmission. Professors Kariuki Njenga and Terry McElwain are lead investigators on a new CDC supported effort to increase surveillance in at-risk areas in Kenya—a country previously hard hit by Rift. Given the increased risk in an El Niño year, surveillance, diagnosis, and reporting efforts are currently being ramped up. These approaches allow limited resources to be strategically employed where they will be most effective, supporting our mission to improve public health and human opportunity everywhere.

Guy Palmer
Creighton Endowed Chair and
WSU Senior Director of Global Health