republic of sierra leone

The Zika virus has gone from an obscure disease to an international public health emergency.

Researchers have been able to trace the gradual spread of Zika — slowly for decades and then, in the words of World Health Organization head Dr. Margaret Chan, “explosively” since 2015, when it was first detected in Brazil. Now the virus has reached more than 20 countries and territories in the Americas.


The virus was first identified in a rhesus monkey in the tropical Zika Forest in Uganda. The monkey was part of a study to identify viruses carried by mosquitoes. Researchers found that the monkey contracted a “hitherto unrecorded virus.”

1951 - 1981: AFRICA

Evidence of human infection was found in a number of countries in Africa, including Central African Republic, Egypt, Gabon, Nigeria, Sierra Leone, Tanzania and Uganda. As a rule, the number of cases over the decades was relatively small, but that could reflect the fact that symptoms are mild, nonexistent or mistaken for those of other viruses. 

1951 - 1981: ASIA

Evidence of human infection was found in some Asian countries, including India, Indonesia, Malaysia, the Philippines, Thailand and Vietnam.


In April 2007, an outbreak began in Yap Island in the Pacific Ocean — the first detection of the virus outside the African and Asian continents and the first evidence that Zika could spread rapidly through a population.


An outbreak occurred in the islands of French Polynesia, with an estimated 20,000 possible cases, and spread to other Pacific Islands: Cook Islands, Easter Island, New Caledonia, Solomon Islands and Vanuatu.

2015-2016: THE AMERICAS

The rough estimate of current cases in Brazil is 500,000 to 1.5 million, although it could be higher because many people who are infected show no symptoms.

Read the full story here.

These maps reflect data available from the CDC as of February 5. Due to space constraints, not all countries are labeled.

Source: Centers for Disease Control and Prevention, Pan American Health Organization

Credit: Alyson Hurt/NPR

“Peace Corps is an organization for which I have a strong personal affinity. The dedication and professionalism of Peace Corps Volunteers in our education system made a great impact on me during my formative years. Since 1962, Peace Corps Volunteers have been great ambassadors to my country and I know they will continue to play a critical role as we write the next chapter in the history of my country.” 

During his visit to Peace Corps Headquarters today, President Ernest Bai Koroma of the Republic of Sierra Leone was reunited with Returned Peace Corps Volunteer Sharon Kasper Alvarado. Alvarado served in Sierra Leone from 1964 to 1966 as an education Volunteer and got to know President Koroma’s family and schoolmates. The two had not seen each other for nearly 50 years.