EHRLICHIOSIS / ANAPLASMOSIS

EHRLICHIOSIS / ANAPLASMOSIS

Wisconsin Division of Public Health Disease Surveillance Manual (EpiNet, December 2008)

EHRLICHIOSIS/ANAPLASMOSIS

I.          IDENTIFICATION

A.        CLINICAL DESCRIPTION: A tick-borne illness characterized by acute onset, headache, myalgia, rigors, and malaise. Nausea, vomiting, or rash may be present in some cases. Clinical laboratory findings may include thrombocytopenia, leukopenia, and elevated liver enzymes. Intracytoplasmic bacterial aggregates (morulae) may be visible in the leukocytes of some patients.
Four categories of ehrlichiosis/anaplasmosis should be reported for the purpose of surveillance:

1) Human granulocytic anaplasmosis (HGA) or most currently referred to as human anaplasmosis (HA) is caused by the bacteria Anaplasma phagocytophila. This is the only type known to occur in Wisconsin. (Note nomenclature change: HA was formerly called human granulocytic ehrlichiosis or HGE.)
2) Human monocytic ehrlichiosis (HME) caused by Ehrlichia chaffeensis
3) Human ehrlichiosis caused by Ehrlichia ewingii, and
4) Human ehrlichiosis/anaplasmosis- undetermined cases including a) case-patients with Ehrlichia chaffeensis results and no history of travel outside of Wisconsin but did not have HA testing, or b) results with cross-reactivity or possible dual infection with more than one agents (cases with test results less than four fold difference in titers between two different species that are unable to be resolved by further testing).

Note: Since human anaplasmosis is the only species known to occur in Wisconsin, it is important to ask about travel history outside of Wisconsin whenever any of the other species (Ehrlichia chaffeensis, Ehrlichia ewingii) are reported.

B.        REPORTING CRITERIA: Confirmatory or supportive laboratory findings in an individual with a clinically compatible illness.

C.        LABORATORY CRITERIA:

1) Laboratory confirmed:

Fourfold change in IgG antibody titer to antigen from an Ehrlichia/Anaplasma species by indirect immunofluorescence assay (IFA) between paired serum samples (one collected in the first week of illness and second collected 2-4 weeks later), OR

Detection of DNA from an Ehrlichia/Anaplasma species by polymerase chain reaction (PCR) assay, OR

Immunohistochemical detection of antigens from an Ehrlichia/Anaplasma species in a skin biopsy or autopsy sample, OR

Isolation of an Ehrlichia/Anaplasma species from a clinical specimen in cell culture.


2) Laboratory supportive:

Serological evidence of elevated IgG or IgM antibody titer to an Ehrlichia/Anaplasma species by IFA, enzyme-linked immunosorbent assay (ELISA), dot-ELISA, or other assays in other format, OR

Identification of morulae in the cytoplasm of monocytes or macrophages (for ehrlichiosis) or in neutrophils or eosinophils (for anaplasmosis) by microscopic examination.


NOTE: Clinical signs of disease caused by these agents are similar, therefore testing for one or more species may be necessary. Since serologic cross-reactions may occur among the different tests, all laboratory testing must be conducted using appropriate controls and reagents necessary for accurate etiologic diagnosis, and should be performed by experienced personnel with appropriate training.

D.        WISCONSIN CASE DEFINITION:

Clinical criteria for the purpose of surveillance:
Any reported fever and one or more of the following: headache, myalgia, anemia, leucopenia, thromobocytopenia, or any hepatic transaminase elevation.

1. Confirmed ehrlichiosis/anaplasmosis: A clinically compatible illness that is laboratory confirmed (see above).

2. Probable ehrlichiosis/anaplasmosis: A clinically compatible illness that has supportive laboratory results (see above) or any cases of human ehrlichiosis/anaplasmosis undetermined.

II.        ACTIONS REQUIRED / PREVENTION MEASURES

A.        WISCONSIN DISEASE SURVEILLANCE CATEGORY II: Report to the patient's local health officer on an Acute and Communicable Disease Case Report (DPH 4151) or other means within 72 hours of the identification of a case or suspected case.

B.        EPIDEMIOLOGY REPORTS REQUESTED:

Acute and Communicable Diseases Case Report (DPH 4151).

The Tick-borne Rickettsial Disease Case Report (CDC 55.1, Rev. 1/2008) is available on the CDC website: http://www.cdc.gov/ncidod/dvrd/ehrlichia/Index.htm

C.        PUBLIC HEALTH INTERVENTIONS:
Patient education as needed to minimize future risk of exposure to infected ticks.

III.       CONTACTS FOR CONSULTATION

A.        BCDP / COMMUNICABLE DISEASE EPIDEMIOLOGY SECTION: Vectorborne Coordinator at (608) 267-9000.

B.        REGIONAL STAFF: See Epinet Introduction: “REGIONAL OFFICE CONTACTS”.

C.        WSLH / EHRLICHIA SEROLOGY: (608) 262-0248.
            Testing will not be done at the WSLH but will be forwarded to CDC.

IV.       RELATED REFERENCES

“Ehrlichiosis” DPH Disease Fact Sheet Series, (Rev. 12/03)
http://dhfs.wisconsin.gov/communicable/communicable/factsheets/Ehrlichiosis.htm

Heymann DL, ed. EHRLICHIOSIS. In: Control of Communicable Diseases Manual. 18th ed. Washington, DC: American Public Health Association, 2004:187-190.

Pickering LK, ed. Ehrlichia Infections. In: Red Book: 2003 Report of the Committee on Infectious Diseases. 26th ed. Elk Grove Village, IL: American Academy of Pediatrics, 2003:266-269.