Ehrlichia and Anaplasma in Florida
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Permanent Link: http://ufdc.ufl.edu/IR00000849/00001
 Material Information
Title: Ehrlichia and Anaplasma in Florida
Physical Description: Fact Sheet
Creator: Lord, Cynthia C
Connelly, C. Roxanne Rutledge
Publisher: University of Florida Cooperative Extension Service, Institute of Food and Agriculture Sciences, EDIS
Place of Publication: Gainesville, Fla.
Publication Date: 2012
Abstract: Ehrlichia and Anaplasma are related bacterial genera containing species that can cause disease in both humans and domestic animals. The diseases are often referred to simply as ehrlichiosis or anaplasmosis, but there are multiple species of bacteria that can cause different disease symptoms and have different vectors.
Acquisition: Collected for University of Florida's Institutional Repository by the UFIR Self-Submittal tool. Submitted by Diana Hagan.
Publication Status: Published
General Note: "Publication #ENY-662"
General Note: " Original publication date August 2001. Revised March 2012."
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Source Institution: University of Florida Institutional Repository
Holding Location: University of Florida
Rights Management: All rights reserved by the submitter.
System ID: IR00000849:00001


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ENY-662 Ehrlichia and Anaplasma in Florida1Cynthia C. Lord and C. Roxanne Rutledge Connelly2 1. This document is ENY-662, one of a series of the Entomology and Nematology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date August 2001. Revised March 2012. Visit the EDIS website at http://edis.ifas.u. edu 2. Cynthia C. Lord and C. Roxanne Rutledge Connelly, associate professors, Florida Medical Entomology Laboratory, Vero Beach, FL; Entomology and Nematology Department, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611.The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or aliations. U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A&M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Millie Ferrer-Chancy, Interim DeanEhrlichia and Anaplasma are related bacterial genera containing species that can cause disease in both humans and domestic animals. e diseases are oen referred to simply as ehrlichiosis or anaplasmosis, but there are multiple species of bacteria that can cause dierent disease symptoms and have dierent vectors. e taxonomy (naming system and how they are related) was recently revised. is resulted in some species previously in Ehrlichia to now be in Anaplasma ; you will nd older literature using the old names. States vary in whether they require reporting of these diseases, and when reporting began. Travel complicates our understanding, as diagnosis may occur much later and in a dierent place than infection. erefore, we do not have a complete picture of the epidemiology of many of these bacteria. Currently, two species of Ehrlichia in the United States and one in Japan are known to cause disease in humans. Only one species of Anaplasma has been found in the US that causes disease in humans. However, others will likely be recognized in the future as methods of detection improve.Humansere is one species in each genera that is of most concern for human disease in the U.S. Human monocytic ehrlichiosis (HME) is caused by E. chaeensis and human granulocytic anaplasmosis (HGA) is caused by A. phagocytophilum Previously, A. phagocytophilum was known as E. phagocytophila, and the disease was called human granulocytic ehrlichiosis or HME. Clinically, they are dicult to dierentiate. Symptoms for both include fever, headache, malaise, and muscle aches. Rashes occur more frequently with HME than HGA. Treatment for both is with antibiotics in the tetracycline family, most commonly doxycycline. Fatalities are rare (2% of diagnosed cases), but can occur as the result of complications from infection. Complete diagnosis requires serological or molecular tests to dierentiate the bacterial species, but treatment should begin aer clinical diagnosis. Asymptomatic infections probably occur with all Ehrlichia and Anaplasma. Improved diagnostic tools and an increased awareness of ehrlichiosis and anaplasmosis are revealing that these infections are more common than previously suspected. e incidence rates across the country have been steadily increasing.Horses and DogsBoth horses and dogs are susceptible to Ehrlichia and Anaplasma, although the species involved vary (see below for details). In dogs, the clinical signs for dierent types of ehrlichiosis and anaplasmosis are similar and dicult to separate clinically. ese include fever, epilepsy, incoordina tion, lethargy, anemia, and bleeding episodes. Asymptomatic infections are probably common. e clinical signs in horses are more easily dierentiated. Signs of equine granulocytic anaplasmosis (EGA, A. phagocytophilum ) include fever, lethargy, anorexia, ataxia and limb edema. Potomac horse fever, Neorickettsia risticii (formerly equine monocytic ehrlichiosis) oen manifests as colitis (inammation of the colon), resulting in diarrhea, colic, loss of appetite, depression, and possibly laminitis.


2 Biology of Ehrlichia and AnaplasmaEhrlichia and Anaplasma are bacteria, related to Rickettsia and are obligate intracellular parasites, meaning they cannot survive outside of a cell. ese bacteria have only recently begun to receive much research attention, and there are still many questions about their transmission cycles and reservoir hosts. ere are likely to be continued taxonomic revisions of Ehrlichia and Anaplasma as further research occurs. Many Ehrlichia and Anaplasma are tick-borne, although there are some species that use other invertebrates as intermediate hosts, such as snails and helminths. e transmission cycles for some species have not yet been determined. ese bacteria are oen dierentiated based on the mammalian cell type they infect. Monocytes, granulocytes, and neutrophils are most frequently involved, and the common name of the resulting disease reects the cell type (e.g., monocytic or granulocytic).Species of Ehrlichia and Anaplasma in the U.S.Ehrlichia chaeensis Disease: humans (HME), rarely monocytic erhlichiosis in dogs. Vectors: Amblyomma americanum (lone star tick); possibly Dermacentor variabilis (American dog tick). Distribution: HME has been diagnosed from most states in the U.S. It is more common in the southeastern U.S., largely congruent with the distribution of A. americanum. Reservoir hosts: probably white-tailed deer, rodents and/or dogs. Anaplasma phagocytophilum (formerly Ehrlichia phagocytophila ) Disease: granulocytic anaplasmosis in humans (HGA), horses (EGA), dogs, cattle. Vector: In the eastern U.S., Ixodes scapularis (black-legged tick or deer tick). Elsewhere, other members of the I. ricinus group ( I. ricinus, I. pacicus, I. persulcatus). Distribution: U.S., Europe, Asia. In the U.S., it has been reported from areas where I. scapularis and I. pacicus are present, predominately in the Northeast, Midwest and California. Cases have been identied in Florida, but the level of transmission is unclear. Reservoir hosts: rodents, possibly deer. A note on species nomenclature: Initially, the agent of HGE was identied as an Ehrlichia but not named. Later, it was determined that the agent of HGE, E. equi (cause of equine granulocytic ehrlichiosis), and E. phagocytophila (cause of ehrlichiosis in cattle and deer in Europe), were genetically almost identical and should be in the genus Anaplasma e name E. phagocytophila had priority and therefore all three agents are now considered A. phagocytophilum. (Latin names have gender, and the genus and species must agree, so the specic name changed slightly to agree with the genus). Older literature may dierentiate between the three originally described agents, or use the older names. Ehrlichia canis Disease: primarily dogs (canine monocytic ehrlichiosis). is species has been linked to disease in humans, but is rare and poorly understood in humans. Vectors: Rhipicephalus sanguineus (brown dog tick), possibly A. americanum. Distribution: worldwide. Ehrlichia ewingii Disease: primarily dogs (canine granulocytic ehrlichiosis). Human disease is known but relatively rare. However, clinical signs for E. ewingii and E. chaeensis infections are indistinguishable and serologic tests cannot dierentiate the two. As testing and reporting improve, our understanding of the distribution and importance of these two species is likely to change. Vectors: A. americanum; involvement of other tick species unclear at this time. Distribution: primarily the south-central states in the United States. Ehrlichia murislike (EML) is organism was recently recognized as a cause of human disease. To date, only 4 cases have been identied (none in Florida). is organism has not been fully characterized, and its role in ehrlichiosis epidemiology is unclear. It is thought to be tick-borne, and deer or dogs may serve as reservoir species.


3 Neorickettsia risticii Disease: Horses (Potomac horse fever or equine monocytic ehrlichiosis); has also been isolated from dogs. An equine vaccine is available, but protection is of short duration, and booster inoculations are required. Formerly in Ehrlichia. Vector: Not tick-borne. Horses are primarily infected by ingesting intermediate hosts containing the bacteria. Aquatic insects, snails, and helminths are likely to be involved in the transmission cycle. Distribution: much of North America, particularly the east coast; Europe. More common along major waterways and in summer. Other Ehrlichia, Anaplasma and related species. Ehrlichia and Anaplasma are closely related to the genus Rickettisa. is genus includes the agent of Rocky mountain spotted fever, R. rickettsia, and other disease-causing agents. Other species in Ehrlichia and Anaplasma are known veterinary pathogens, and we may nd that there is involvement in human disease as we study these bacteria further. While many of these bacteria are tick-borne, some have other arthropod vectors or the transmission cycle is unknown. Further research is needed to understand this complex group of bacteria.Florida SituationTypically, there are 1 reported cases of HGA and 5 cases of HME in Florida each year. More cases probably occur, but are not severe enough to cause people to seek medical attention or are not conrmed by laboratory tests. Veterinary cases are not always reported, but both canine and equine anaplasmosis/ehrlichiosis occur in Florida. Several species of ticks which transmit Ehrlichia spp. or Anaplasma phagocytophilum are present in Florida. ese include I. scapularis, A. americanum, and D. variablis (Fig. 1).Prevention and ManagementAs with any vector-borne pathogen, the primary disease preventative measure is to minimize contact with the vectors. For humans, protective clothing, such as long pants and socks tucked into pants will reduce tick contact; repellents containing DEET are eective against most ticks. Permethrin-based repellents can be sprayed on boots and clothing. For dogs, there are various treatments in sprays, spot-ons and collars (active ingredients include permethrin, pronil, amitraz). Permethrin and pyrethroid-based sprays and spot-ons for horses will reduce tick bites. Use all pesticides in accordance with label directions. For all host species, thorough tick checks and grooming to remove attached ticks will reduce transmission of tickborne pathogens. Use ne-tipped forceps to remove ticks; grasp the tick near the skin and pull straight back. Do not squeeze the abdomen or apply heat or petroleum products; this may cause the tick to regurgitate into the host! Tick population reduction is dicult and it is unclear how eective it will be in reducing infection rates. Various methods have been tested, including vegetation management, acaracide treatment, host exclusion, and host treatment. Treatment of deer, via treated feed or feeding stations that apply acaricide to hosts, are promising methods for population reduction of ticks that feed on deer.Further Informationhttp://www.cdc.gov/ehrlichiosis/ http://www.cdc.gov/anaplasmosis/ Dahlgren, FS, Mandel, EJ, Krebs, JW, Massung, RF and McQuiston, JH. 2011. Increasing incidence of Ehrlichia chaeensis and Anaplasma phagocytophilum in the United States, 2000. Am. J. Trop. Med. Hyg. 85: 124. Ticks: http://edis.ifas.u.edu/IG088 Figure 1. Ehrlichia vectors in Florida Credits: James Newman