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Madariaga virus spreads to Haiti

Jan. 18, 2019: EPI members, including director Glenn Morris, identified Madariaga virus for the first time in Haitian children in 2015-2016. Prior to their work, this emerging infectious agent had been found mostly in animals of South and Central America, with the first human outbreak occurring in Panama in 2010.

Madariaga virus spreads to Haiti

Madariaga virus (MADV), or South American eastern equine encephalitis virus (EEEV), has--until now-- been found primarily in animals of South and Central America, with the first human outbreak occurring in Panama in 2010. Now, scientists writing in PLOS Neglected Tropical Diseases report the identification of MADV in eight children in Haiti in 2015 and 2016.

Madariaga is a mosquito-borne disease transmitted to humans from animals including horses, mice, rats and bats. Little is known about its epidemiology or life cycle. While MADV can cause serious encephalitis, surveys in Panama after the 2010 outbreak found that between 2 to 5 percent of the population in the areas affected by MADV had evidence of prior infection, suggesting that mild or asymptomatic infections are common.

Glenn Morris, director of the Emerging Pathogens Institute at the University of Florida and a professor in the college of medicine, leads a team that maintains a surveillance program at a school clinic in Haiti. Additional UF team members with EPI affiliations include: Valery Madsden Beau De Rochars, John Lednicky and Bernard Okech, professors of public health and health professions; and Marco Salemi, a pathology professor in the college of medicine.

Since 2014, Morris’s team has collected blood samples of children presenting to the clinic with acute febrile illness. In April 2015, one such sample--collected from an 8-year-old girl in the Gressier/Leogane region of Haiti--tested positive for MADV. The virus was then cultured from an additional seven patients from the same cohort throughout 2016.

Symptoms from the patients most closely resembled those seen in dengue fever infection, and no patients had encephalitis. All the strains isolated were very similar, and using available information on the genetic sequence of the MADV cultured from the patients, the team was able to hypothesize that the virus was introduced to Haiti from Panama sometime between October 2012 and January 2015.

"Our data indicate that this virus, which has the potential for causing serious illness, has recently been introduced into Haiti, and raises the possibility that it might move into other parts of the Caribbean or North America," the researchers say.

Creator credits

Originally written as a PLOS Neglected Tropical Diseases press release by Avren Keating (, and issued via EurekaAlert! on Jan. 10, 2019. Reposted on EPI’s website with light editing on Jan. 18, 2019.

Graphic courtesy of Morris et al, 2019: [A]. Mock-infected Vero E6 cells, 23 days post-seed. [B]. Vero E6 cells inoculated with plasma sample 1-1901. Infected cells develop dark, granulated cytoplasms with inclusion bodies, the cells enlarge, and dead cells detach from the growing surface.

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Open Access – full text journal article available here.

Glenn Morris’s EPI profile

Valery Madsen Beau De Rochars' profile

John Lednicky’s EPI profile

Bernard Okech’s EPI profile

Marco Salemi’s EPI profile