Experimental Infection of North American Sheep with Ehrlichia ruminantium

• Published in: Pathogens (Basel) Vol. 10; no. 4; p. 451
• Main Authors: Nair, Arathy, Hove, Paidashe, Liu, Huitao, Wang, Ying, Cino-Ozuna, Ada G, Henningson, Jamie, Ganta, Charan K, Ganta, Roman R
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 09.04.2021; MDPI
• Subjects: Anaplasmataceae pathogens; Animals; Antibody response; Bacterial infections; Coronary artery disease; Cowdria ruminantium; Disease; Edema; Ehrlichia ruminantium; Experimental infection; Fever; Heart diseases; heartwater; Heartwater fever; Hemorrhage; IgG antibody; Immunoglobulin G; Importation; Infections; Larynx; Organs; Pathogenesis; Pathogens; rickettsials; Sheep; tick-borne diseases; Western Hemisphere; Nigeria; United States > US; North America; Africa; Anaplasmataceae pathogens; heartwater; tick-borne diseases; Cowdria ruminantium; rickettsials
• ISSN: 2076-0817; 2076-0817
• DOI: 10.3390/pathogens10040451

, a tick-borne rickettsial, causes heartwater in ruminants resulting from vascular damage. Severity of heartwater varies greatly in ruminant species and breeds, age of animals and for diverse geographic . strains. and a tick vector, , originating from Africa, are well established in certain Caribbean islands two centuries ago. Besides the possibility of introduction of heartwater through African exotic animal importation, presence of the pathogen, and the tick vector in the Caribbean pose a high risk to ruminants in the USA and other western hemisphere countries. Scientific evidence supporting the heartwater threat to nonendemic regions, however, is lacking. We describe the first infection study in sheep reared in the USA with seven strains. All infected sheep exhibited clinical signs characteristic of subacute to subclinical disease, which included labored breathing, depression, coughing, and nasal discharges. Gross and microscopic lesions consistent with heartwater disease including edema and hemorrhage were observed in several organs. Pathogen-specific IgG antibody response was detected in animals infected with all seven strains, while molecular analysis confirmed the pathogen presence only when infected with in vitro cultures. This is the first infection study demonstrating severe heartwater in sheep reared in North America.