Evidence of Ehrlichia chaffeensis in Argentina through molecular detection in marsh deer (Blastocerus dichotomus).

Guillemi EC, et al. Int J Parasitol Parasites Wildl. 2019.


Vector-borne pathogens are responsible for serious emerging diseases and have been widely described in wildlife. Ehrlichia chaffeensis causes the zoonotic “monocytic ehrlichiosis” in humans, is transmitted by the tick Amblyomma americanum and its reservoir host is the white-tailed deer (Odocoileus virginianus) in North America. Little is known about the native reservoir and the tick vectors involved in the transmission cycle in South America. We report here the detection of E. chaffeensis in a study on marsh deer (Blastocerus dichotomus) mortality in Argentina, in different time periods between 2007 and 2016. Four deer, from two distinct populations, were positive for E. chaffeensis through molecular methods. Additionally, the variable-length PCR target (VLPT) region of positive samples was genotyped. Our results provide the first evidence of E. chaffeensis in autochthonous Cervidae from Argentina, contributing to uncover the distribution of this tick-borne infection in South America.

1-s2.0-s2213224418300889-gr3_lrgFig. 3. Dead marsh deer with high tick burden.


More on Ehrlichia:  The author brings up a valid point about the potential of there being undiagnosed Ehrlichia behind a ME/CFS diagnosis in a subset of patients since it infects white blood cells and the mitochondria.  The article also gives helpful percentages of symptoms and the following information:

  • Fever/chills and headache (majority of cases)

  • Fatigue/malaise (over two-thirds of cases)

  • Muscle/joint pain (25% – 50%)

  • Nausea, vomiting and/or diarrhea (25% – 50%)

  • Cough (25% – 50%)

  • Confusion or brain fog (50% of children, less common in adults)

  • Lymphadenopathy (47% – 56% of children, less common in adults)

  • Red eyes (occasionally)

  • Rash (approximately 60% of children and 30% of adults)


Ehrlichia chaffeensis has been shown to survive for over a week in refrigerated blood. Therefore these bacteria may present a risk for transmission through blood transfusion and organ donation. It has also been suggested that ehrlichiosis can be transmitted from mother to child, and through direct contact with slaughtered deer. (14, 15)