Martin J. O'Malley Anthony G. Brown Governor Lt. Governor A Publication of the Maryland Department of Health and Mental Hygiene Joshua M. Sharfstein, M.D. Secretary The Laboratories Administration—Maryland’s State Public Health Laboratory also been reported Laboratory in 2010.1 Other less common tick-borne Diagnosis of diseases in the United States Tick-borne include tick-borne relapsing fever (TBRF) and Diseases Rickettsia phillipi, proposed. Health care providers Ticks can harbor should consider and test for these more than one infections in patients with disease-causing compatible syndromes. A history Figure 1: Vectors for Lyme disease; the blacklegged tick, Ixodes agent and diagnosis scapularis. From left, an adult female, an adult male, a nymph, of a tick bite is not and a larva. Photo credit: CDC PHIL can be difficult necessarily a prerequisite for the inclusion of these part of the human body. In most cases, diseases in the differential diagnosis Tick-borne illnesses are caused by a the tick must be attached for 36-48 hours for patients with compatible illness. variety of pathogens, including rickettsia or more before the Lyme disease bacteria, viruses, and protozoa. Since bacterium can be transmitted. ticks can harbor more than one disease- Lyme Disease Characteristic of early localized disease causing agent, patients can be infected is the presence of a skin rash (Figure 2.) with more than one pathogen at the same Lyme disease is caused by a spirochete Erythema migrans (EM) is a skin lesion time, compounding the difficulty in Borrelia burgdorferi. The vector that (Continued on page 2) diagnosis and treatment. The incidence carries B. burgdorferi in the U.S. Mid- varies by geographic location and atlantic, Northeast, and North Central causative agent. The most common tick- states is the blacklegged tick (also known borne disease in Maryland and also in as the deer tick) Ixodes scapularis USA is Lyme disease (LD), but cases of (Figure 1.) Rocky Mountain spotted fever (RMSF), October 2011 Babesiosis, Anaplasmosis (human The tick goes through three life stages. granulocytic anaplasmosis HGA or The larva hatch from eggs and molt into HGE), and Ehrlichiosis (human the nymph stage, which develops into Volume 15, Number 10 monocytic ehrlichiosis or HME) have the adult stage. Ticks can attach to any Critical Link • www.dhmh.state.md.us/labs/html/critical-link.html • October 2011 • Vol. 15, No. 10 Page 1 PRODUCTION MANAGER Georgia Corso EDITORIAL BOARD Figure 2: Lyme Disease Erythema Migran (EM) Photo credit: CDC PHIL Prince Kassim, Ph.D. Fizza Majid, Ph.D. (Continued from page 1) Robert Myers, Ph.D. Laboratory Diagnosis of Diagnosis of early-stage localized Lyme Maria Paz Carlos, DVM, Ph.D. Tick Borne Diseases disease can be made on the basis of EM alone without any additional laboratory Jafar Razeq, Ph.D. with a bull’s-eye pattern that develops at confirmatory testing.2 Early/late stage Jim Svrjcek, B.A. the site of the tick bite; it is usually disseminated disease requires laboratory present 7 to14 days after the tick bite confirmation. Laboratory confirmation Chengru Zhu, Ph.D. and should be around 5 cm diameter for requires demonstration of antibodies to a firm Lyme disease diagnosis.2 B. burgdorferi in serum or CSF. A two- test approach using a sensitive enzyme LABORATORIES ADMINISTRATION Disseminated disease that may affect the immunoassay (EIA) or immunofluores- musculoskeletal, cardiac, or nervous cence antibody test followed by Western system can follow EM within days or Blot (WB) is highly recommended. Director weeks, and is considered early-stage Follow-up testing of a positive or disseminated disease. Lyme carditis may equivocal EIA with a WB test is Robert Myers, Ph.D. overlap temporally with neurologic recommended by the Centers for Lyme disease (late-stage disseminated Disease Control and Prevention and the disease.) (Continued on page 3) TECHNICAL QUESTIONS Figure 3: Two-tiered serology testing for Lyme disease as recommended by the CDC. 4 National Center for Emerging and Zoonotic Infectious Diseases, Division of Vector Borne Diseases, Bacterial Diseases Branch. Questions concerning technical content of this newsletter Second Test may be referred to First Test Second Test Dr. Robert Myers at 410-767-6100 Enzyme Positive or Signs or IgM and IgG Immunoassay (EIA) Equivocal Result symptoms ≤ Western Blot 30 days The Critical Link is published monthly OR Immunofluores- by the staff of the Negative Result cence Assay (IFA) Laboratories Administration Signs or IgG Western Blot ONLY Department of Health & Mental Hygiene symptoms > 30 days 201 W. Preston Street Consider alternative diagnosis Baltimore, Maryland 21201 OR (Phone 410-767-6909) If patient has signs/symptoms consistent with Lyme disease for ≤ 30 days, consider obtaining a convalescent serum Page 2 Critical Link • www.dhmh.state.md.us/labs/html/critical-link.html • October 2011 • Vol. 15, No. 10 Figures 5 and 6: Dermacentor andersoni, or wood tick, above and Der- macentor variabilis, or dog tick, below. The RMSF distribution in the U.S. by different tick species. Yellow indicates the approximate distri- bution area. Photo credit: CDC PHIL Figure 4: Blacklegged ticks can feed from mammals, birds, rep- tiles, and amphibians. The ticks need to have a new host at each stage of their life, as shown above. Graphic credit: http://www.cdc.gov/ lyme/transmission/blacklegged.html (Continued from page 2) results, so physicians should be headache, abdominal pain, vomiting, Laboratory Diagnosis of informed of all patient medications prior and muscle pain. A rash may also Tick Borne Diseases to testing. The polymerase chain develop, but is often absent in the first reaction (PCR) test detects the DNA of few days. However in some patients, Association of State and Territorial the bacteria that causes Lyme disease. It may never develop. RMSF can be a Public Health Laboratory Directors.3 is sometimes used for patients who have severe or even fatal illness if not treated Lyme IgM Western blot should not be neurological symptoms or Lyme in the first few days of symptoms. The used to diagnose any condition less than arthritis. The PCR test is performed on initial diagnosis is made based on one month in duration due to the high spinal fluid collected from a lumbar clinical signs and symptoms, as well as rate of false positives. puncture (spinal tap) or synovial fluid and medical history, and can later be (collected from an affected joint.) For confirmed serologically with a four-fold The interpretation of WB antibody most patients, standard blood antibody rise in titer by immunofluorescent assays is based on the number of tests are preferred. antibody (IFA.) Antibody titers of 1:64 positive bands: two of three bands (23, are considered evidence of current or 39, 41kDa) for IgM indicate positivity past infections. A four-fold increase of and five out of ten bands (18, 23, 28, 30, Rocky Mountain Spotted titers at a three week interval 39, 41, 45, 58, 66, or 93 kDa) for IgG Fever (RMSF) demonstrates an active infection.4 No positivity. The WB is to be used only microbiological or immunological tests following initial EIA testing, and are sensitive enough to exclude the positive results confirm B. burgdorferi RMSF is a potentially fatal human diagnosis of RMSF within the time infection. Other spirochete diseases, illness caused by Rickettsia rickettsii. It frame of emergency evaluation and such as syphilis and leptospirosis, can is transmitted to humans by the bite of management. The decision to administer cause false positive results, as well as an infected dog tick, Demacentor antibiotics should be based on history, other disease conditions such as HIV variabilis, or wood tick, Dermacentor physical examination, and clinical infection, mononucleosis, and a variety andersoni (Figures 5 and 6) or a brown suspicion, not confirmatory tests. of other autoimmune diseases. dog tick, Rhipicephalus sanguineus. Typical symptoms include fever, Antibiotics can interfere with the test (Continued on page 4) Critical Link • www.dhmh.state.md.us/labs/html/critical-link.html • October 2011 • Vol. 15, No. 10 Page 3 In contrast, HME is caused by Ehrlichia chaffeensis (Figure 10) which infects monocytes. HME is transmitted to humans by the lone star tick, Figure 9: The lone star tick, Ambylomma americanum is found in south- Ambylomma eastern U.S. Photo credit: CDC PHIL americanum Photo Courtesy of CDC (Figure 9.) HGA and HME have the Figure 7: Human granulocytic ehrlichiosis same clinical manifestations. Therefore, A positive immunofluorescence assay (HGE.) Photo credit: CDC PHIL the term ehrlichiosis is used for both (titer great than or equal to 1:64) types of infections. The total duration of suggests current or previous infection. In illness for HME and HGA is unknown. general, the higher the titer, the more No chronic cases have been reported at likely the patient has an active infection. (Continued from page 3) this time. Four-fold rises in titer also indicate Laboratory Diagnosis of active infection. The diagnosis of HME Tick Borne Diseases Infectious forms are injected during tick or HGA rests on either a single elevated bites and the organism enters the immunoglobulin G (IgG) antibody (IFA) vascular system where it infects titer or the demonstration of a four-fold Ehrlichiosis monocytes. It is sequestered in host-cell or greater increase between acute and membrane-limited parasitophorous convalescent IFA titers.5 Serology may vacuoles known as morulae. These can not be helpful in the acute phase of Ehrlichiosis is an infection caused by be readily observed on Giemsa- or illness, and molecular methods, PCR, obligate intracellular, gram-negative Wright's-stained smears of peripheral are recommended in conjunction with rickettsia that infects leukocytes. Human blood from infected persons. IFA. PCR testing should be done on granulocytic anaplasmosis (HGA), whole blood drawn during the first week formerly known as human granulocytic Most cases of ehrlichiosis are probably of symptoms and prior to antibiotic ehrlichiosis (HGE) is caused by subclinical or mild, but the infection can treatment.