West Africa is currently experiencing the largest outbreak of Ebola virus disease (EVD) in history, with over 1,000 deaths and the declaration of an international public health emergency from the World Health Organization. This week, scientists believe they may have identified Patient Zero: a two-year-old from Guinea. The case was described in the April issue of The New England Journal of Medicine.
Early in December 2013, the child fell ill in the town Guéckédou, which is along Guinea’s border with Sierra Leone and Liberia. Symptoms included vomiting, fever, and had black stool (which can indicate bleeding somewhere in the GI tract) for four days, before succumbing to the illness on December 6.
The Ebola virus can spread through contact of bodily fluids, like vomit, urine, and diarrhea. The child’s family were likely doing everything they could to provide care, which would have left them completely exposed. That seems to be the case, as EVD then claimed the lives of the family members, starting with the mother on December 13, the 3-year-old sister on December 29, and the grandmother on January 1. All of them had the same symptoms.
It was at the grandmother’s funeral that the illness really began to spread. It is believed that two mourners who had come into contact with the grandmother’s bodily fluids brought the virus back to their respective villages, as the virus can still be transmitted after death. The Guinean Ministry of Health was not informed of the situation until early March 2014. Two days later, blood tests from 20 different patients from Guéckédou and two nearby cities had been collected. Laboratory testing would reveal that the illness was indeed caused by Ebola.
By the time it had been declared an epidemic in March, 59 people in Guinea had already died because of the disease. It was confirmed later that month in Liberia, and Sierra Leone experienced its first fatality of the outbreak in May.
What has not been made entirely clear is how the child picked up the virus in the first place. The virus has a natural reservoir in fruit bats, and some strains can live inside other animals like monkeys, chimps, porcupines, and forest antelope. Many in West Africa eat this wild bushmeat which has previously been shown to spread the virus and cause human illness. The toddler’s hometown of Guéckédou is known for its large market, where bushmeat and other animal products are offered.
However, the strain causing the current outbreak is not one that is endemic to the region, which has been somewhat troubling. The strain is known as Ebola Zaire, which comes from the Democratic Republic of Congo (formerly Zaire), which is about 3500 km (2100 mi) away. Officials do not believe the virus was intentionally brought to Guinea. Is it possible that an Ebola-harboring bat flew all that way? While there are some fruit bats that can make impressive migrations, the chances are rather slim.