Infectious Diseases Conference

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Infectious Diseases Conference

• April 12th 2004
• Charles de Comarmond MD

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Present Medical History

• 40 yr old white male with 3 wk history of fever,
  chills and malaise.
• Symptoms started after repairing a well pump.
  Reported fevers of 104.8 F.
• C/o headaches, worsening in the supine position,
  associated with nausea.
• Reports onset of arthralgias w/o swelling or
  redness of joints one week PTA.

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Present Medical History

• Denied any cough, abdominal pain, diarrhea, or
  urinary symptoms
• Reported onset of sore throat 4 days PTA
• Reports contact with domestic cats, dogs, rats
  and parrots. Denied any animal or insect bite.
• Denied any travel outside of West Texas.
• Denied any rash, oral sores, neck stiffness,
  jaundice or lymphadenopathy,

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Past Medical History

• Borderline HTN
• Hx of basal cell carcinoma
• Employed as service manager for phone company
• No Hx of recreational drug use
• ROS unremarkable

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Vitals
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Physical exam

• SKIN No rash, healed wound RT index finger
• HEENT Suboccipital lymphadenopathy
• CHEST Clear
• HEART S1S2, no murmur

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Physical exam

• ABD Hepatomegaly, non tender, smooth surface,
  approx. span 18 cm, tip of spleen palpable
• GEN. single descended testes
• EXT. Normal
• NEURO AAOx3

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Labs
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dif
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Differential diagnosis

• Infectious mononucleosis syndrome
• Epstein-Barr virus
• Cytomegalovirus
• Toxoplasma gondii
• Primary HIV syndrome

Dif.Dx
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Differential diagnosis

• Leptospirosis (Leptospira sp.)
• Tularemia (Francisella tularensis)
• Bartonellosis (Bartonella Hensleii)
• Q fever (Coxiella burnetii)
• Psitacosis (Chlamydia psitacosis)
• Pasteurella multocida
• Ehrlichiosis (Ehrlichia chafeensis/equi)
• Viral hepatitis (Hep. A, B, C)

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DECISION MAKING

• LABS
• Epstein Barr VCA IgG 12560
• Epstein Barr VCA IgM lt110
• CMV IgG gt1.99
• Toxoplasma Gondii IgM lt0.8
• HIV Ab. None detected
• Francisella tularensis IgG lt0.2
• Francisella tularensis IgM lt0.2
• Francisella tularensis IgA lt0.2
• B. Hensleii IgG, IgM none detected
• C. burnetti IgG, IgM none detected

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DECISION MAKING

• LABS cont.
• P. multocida IgG, IgM none detected
• Leptospira IgG, IgM none detected
• Hepatitis A, B, C abs. None detected
• C. psitacosis IgM lt110
• E. equi IgG lt180
• E. equi IgM lt180
• E. chafeensis IgG lt140
• E. chafeensis IgM 1640

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EHRLICHIOSIS
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Objectives

• Epidemiology
• Pathogenesis
• Clinical manifestation
• Clinical manifestation in HIV patients
• Diagnosis
• Microscopic diagnosis
• Serologic diagnosis
• Treatment

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EHRLICHIOSIS

• History
• Until 1987, infections by members of the genus
  Ehrlichia were known mainly as veterinary
  diseases, recognized as causing human illness
  only in Asia
• The first diagnosed case of human ehrlichiosis in
  the US occurred in a 51-year-old man who became
  ill in April 1986 in rural Arkansas.
• The patient's serum contained antibodies reactive
  at a high titer with Ehrlichia canis, which is
  genetically and antigenically closely related to
  the subsequently identified Ehrlichia
  chaffeensis, the etiologic agent of human
  monocytotropic ehrlichiosis (HME)
• In 1994, an Ehrlichia (anaplasma)
  phagocytophila-like organism was reported as the
  causative agent of a distinctly different
  infection, human granulocytotropic ehrlichiosis
  (HGE)
• In 1999 Ehrlichia ewingii was shown to cause
  human illness

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Etiology

• Ehrlichiae are small (0.5 um) gram-negative
  bacteria.
• Their clustered inclusion-like appearance in the
  host cell vacuoles is called a morula, from the
  latin word for "mulberry"
• DNA comparisons indicate that Ehrlichia and
  Rickettsia both evolved from a common ancestor
• Coxiella and Chlamydia are phylogenetically
  unrelated to Ehrlichia

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Epidemiology

• Human ehrlichioses in the United States are
  tick-borne zoonoses
• The seasonality of HME, with a peak incidence in
  May through July, suggests a vector-transmitted
  infection.
• Higher incidence in men in rural and suburban
  areas and involve recreational, peridomestic,
  occupational, and military activities.

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Human monocytotrophic Ehrlichiosis

• Documented cases of HME range over 30 states,
  particularly in the south central and
  southeastern United States
• Regions conform to the distribution of the Lone
  Star tick, Amblyomma americanum, which along with
  white-tailed deer has been found infected in
  nature
• The incidence of HME is 2 to 5 cases per 100,000
  population (USA) from seroprevalence studies

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Human granulocytotrophic Ehrlichiosis

• HGE has a year-round seasonal occurrence, with a
  bimodal distribution peaking in July and again in
  November in accordance with the activity of
  nymphal and adult stages, respectively, of Ixodes
  scapularis ticks in the eastern United States.
• The incidence of HGE is not truly known
• 3 to 16 cases per 100,000 population (USA)
• 51 to 58 cases per 100,000 population
  (Connecticut, Wisconsin)

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Human granulocytotrophic Ehrlichiosis

• Between 6 and 21 of patients with HGE also have
  serologic evidence of Borrelia burgdorferi or
  Babesia microti infection, both agents also
  transmitted by Ixodes spp. tick bites.
• Ehrlichia (anaplasma) phagocytophila -group
  ehrlichiae are transmitted to humans by the bites
  of nymphal and adult Ixodes scapularis in the
  eastern United States, Ixodes pacificus in
  California, and presumably Ixodes ricinus ticks
  in Europe

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Human granulocytotrophic Ehrlichiosis

• The major proven reservoir host is the
  white-footed mouse, Peromyscus leucopus
• Other small mammals found naturally infected or
  have serologic evidence of infection include
• voles,
• woodrats,
• chipmunks and
• white-tailed deer (Odocoileus virginianus)

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Pathogenesis

• After entering the skin by tick bite inoculation
  and spread presumably via lymphatic and blood
  vessels, ehrlichiae invade their target cells of
  the hematopoietic and lymphoreticular systems
• Focal hepatocellular necrosis
• Hepatic granulomas including ring granulomas
• Cholestasis
• Splenic and lymph node necrosis
• Diffuse mononuclear phagocyte hyperplasia of the
  spleen, liver, lymph node, and bone marrow
• Perivascular lymphohistiocytic infiltrates of
  various organs including kidney, heart, liver,
  meninges, brain.
• Interstitial mononuclear cell pneumonitis have
  also been observed

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Pathogenesis

• E. chaffeensis has a direct cytopathic effect
  when grown in cell culture, it appears though
  that host responses might account for some of the
  clinical manifestations
• Ehrlichia chaffeensis circumvents the host
  defenses by inhibiting the fusion of phagosomes
  with lysosomes and inhibiting the
  signal-transduction pathway of interferon-gamma
  anti-ehrlichial activity
• It resides in endosomes that accumulate
  transferrin receptors, presumably a mechanism for
  ehrlichial acquisition of iron
• Ehrlichial growth is inhibited by a reduction of
  available iron via deferoxamine treatment,
  probably because iron is a cofactor in oxidative
  phosphorylation

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Clinical manifestations

• More than 1500 cases of HME have been diagnosed
• Clinical picture in immunocompetent patients is
  of a mild to severe multisystemic illness, with
  approximately 40 of patients requiring
  hospitalization
• In severely immunocompromised patients, E.
  chaffeensis acts as an opportunistic pathogen and
  can cause a fatal overwhelming infection.

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Clinical manifestations

• The median incubation period is 7 days. Symptoms
  at the onset of illness include fever, chills,
  headache, myalgia, and malaise.
• Later in the course, patients often develop
  nausea, anorexia, and weight loss.
• Physical signs are not striking. Less than half
  of patients have a rash, which is maculopapular
  and may be petechial.

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Clinical manifestations

• Adult patients with severe illness are more
  likely to have cough, diarrhea, and
  lymphadenopathy,
• Pediatric patients may develop edema of the hands
  or feet.
• Severe complications include respiratory
  insufficiency (18 require mechanical
  ventilation), renal insufficiency, central
  nervous system abnormalities, gastrointestinal
  hemorrhage, and even death.
• Cerebrospinal fluid pleocytosis usually contains
  a predominance of lymphocytes and increased
  protein concentration.
• Nearly half of the patients with chest imaging
  studies evaluation have infiltrates.

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Clinical Course

• The clinical course of illness ranges from
  asymptomatic seroconversion to a fatal outcome
• In HIV infected individuals, a virulent form of
  HME occurs that is often associated with
  overwhelming infection, a toxic shock- or
  sepsis-like syndrome, and death
• Immune compromise due to corticosteroid therapy
  or immunosuppression with organ transplantation
  is also associated with increased severity

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Clinical Course

• The median duration of hospitalization is about 1
  week
• Fatalities have occurred in approximately 3 of
  patients
• Patients treated with doxycycline or tetracycline
  recover rapidly

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Clinical Infectious Diseases    2001331586-1594
Infections with Ehrlichia chaffeensis and
Ehrlichia ewingii in Persons Coinfected with
Human Immunodeficiency Virus

• The clinical course and laboratory evaluation of
  21 patients coinfected with human
  immunodeficiency virus (HIV) and Ehrlichia
  chaffeensis or Ehrlichia ewingii were reviewed,
  including 13 cases of ehrlichiosis caused by E.
  chaffeensis, 4 caused by E. ewingii, and 4 caused
  by either E. chaffeensis or E. ewingii

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Clinical Infectious Diseases    2001331586-1594
Infections with Ehrlichia chaffeensis and
Ehrlichia ewingii in Persons Coinfected with
Human Immunodeficiency Virus

• Twenty patients were male, and the median CD4 T
  lymphocyte count was 137 cells/ L.
• Exposures to infecting ticks were linked to
  recreational pursuits, occupations, and
  peridomestic activities

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Clinical Infectious Diseases    2001331586-1594
Infections with Ehrlichia chaffeensis and
Ehrlichia ewingii in Persons Coinfected with
Human Immunodeficiency Virus

• Severe manifestations occurred more frequently
  among patients infected with E. chaffeensis than
  they did among patients infected with E. ewingii,
  and all 6 deaths were caused by E. chaffeensis

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Clinical Infectious Diseases    2001331586-1594
Infections with Ehrlichia chaffeensis and
Ehrlichia ewingii in Persons Coinfected with
Human Immunodeficiency Virus

• Infections with E. ewingii were identified
  inpatients from
• central and southern Oklahoma
• southern Missouri
• central Tennessee.

• Infected with E. chaffeensis were identified in
  patients from
• northern Arkansas
• southern Illinois
• central Georgia
• northern Florida
• central and southern Missouri
• central Tennessee

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Clinical Infectious Diseases    2001331586-1594
Infections with Ehrlichia chaffeensis and
Ehrlichia ewingii in Persons Coinfected with
Human Immunodeficiency Virus

• Morulae were visualized in peripheral blood or
  bone marrow leukocytes of 60 of patients in
  this series for whom whole blood, buffy coat, or
  bone marrow aspirate smears were evaluated.
• When quantified, morulae of E. chaffeensis were
  identified in 1 25 of leukocytes,
  predominantly monocytes, and occasionally in
  metamyelocytes and band neutrophils.
• Morulae of E. ewingii were seen in 5 of mature
  and immature neutrophils and in rare eosinophils
  of 1 patient

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Clinical Infectious Diseases    2001331586-1594
Infections with Ehrlichia chaffeensis and
Ehrlichia ewingii in Persons Coinfected with
Human Immunodeficiency Virus

• Initial specimens (n 4) obtained from patients
  with fatal disease were collected a median of 5
  days after onset (range, 4 -15 days), and none
  had diagnostic IgG titers
• Twelve (86) of 14 patients from whom paired
  serum samples were obtained demonstrated a
  4-fold change in titer
• Both patients with fatal disease for whom a
  second serum sample was available (obtained 8
  days and 16 days after onset of illness) failed
  to develop anti E. chaffeensis antibody titers of
  64 before their deaths.

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Diagnosis

• A diagnosis based on epidemiologic and clinical
  factors offers the opportunity to administer
  empirical anti-ehrlichial treatment.
• Physician's index of suspicion must be high, or
  an early diagnosis will not be made.

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Diagnosis

• Patients presenting with the signs and symptoms
  below with history of a recent tick bite in
  endemic regions from May through July should be
  considered as possibly having HME
• Fever
• Leukopenia
• Thrombocytopenia
• Elevated serum transaminase levels

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Diagnosis

• Mild to moderate leukopenia (neutropenia or
  lymphopenia, or both combined, account for the
  leukopenia)
• Thrombocytopenia (platelet count usually between
  50,000 and 140,000/mul, although occasionally
  severe (lt20,000 platelets/mul)
• Elevations of serum hepatic transminase levels

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Diagnosis

• Microscopy
• Immunohistologic demonstration of ehrlichial
  morulae provides a timely, specific diagnosis,
  visualization of ehrlichial morulae in
  circulating leukocytes have been observed in only
  7 of patients with HME.
• Culture
• The "gold standard" for etiologic diagnosis is
  cultivation of the agent
• Immunofluorescence assays
• Peak geometric mean titer of 1280 at 6 weeks
  after onset of symptoms
• Only 22 of the sera tested in the 1st week have
  a titer of 80 or greater
• Genetic testing
• A PCR method employing E. chaffeensis-specific
  primers for amplification and detection of
  ehrlichial DNA from peripheral blood appears to
  be the most sensitive technique for a timely
  laboratory diagnosis

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Serology

• HME IFA
• Cut off 164 IgG/IgM
• IFA high titer sensitivity 95
• X4 IFA titer change sensitivity 82
• False positives
• RMSF, Q fever, EBV, Lyme disease

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Serology

• HGE IFA
• Cut off gt180 IgG/IgM
• IFA high titer sensitivity 78
• X4 IFA titer change sensitivity 63
• False positives
• Q fever, EBV, Lyme disease

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Serology

• WESTERN BLOT
• Recombinant specific antigens
• Sensitivity 68
• Specificity 98

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Modern Pathology 02/20/2004 doi10.1038/modpathol
.3800075 Characteristic peripheral blood findings
in human ehrlichiosis

• A total of 23 patients with clinical and
  laboratory findings suggesting a rickettsial
  infection were tested for Ehrlichia using
  polymerase chain reaction and culture.
• 16 cases contained Ehrlichia DNA by polymerase
  chain reaction (15 E. chaffeensis, one E.
  ewingii), including 14 cases in which the blood
  culture grew Ehrlichia.

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Modern Pathology 02/20/2004 doi10.1038/modpathol
.3800075 Characteristic peripheral blood findings
in human ehrlichiosis

• Cytoplasmic morulae were identified on peripheral
  blood smears in six (five E. chaffeensis, one E.
  ewingii) of 16 (38) of the cases that contained
  Ehrlichia DNA
• 4/4 (100) immunocompromised and 2/12 (17)
  immunocompetent patients

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Modern Pathology 02/20/2004 doi10.1038/modpathol
.3800075 Characteristic peripheral blood findings
in human ehrlichiosis

• Morulae were present in monocytes in E.
  chaffeensis-infected cases and granulocytes in
  the E. ewingii-infected case.
• The number of infected white blood cells were
  sometimes less than 0.2, requiring examination
  of more than 500 white blood cells.

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A degenerating monocyte in the peripheral blood
film contains an intracytoplasmic morula of E.
chaffeensis.
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E. ewingii morula, present in a granulocyte, is
morphologically indistinguishable from E.
chaffeensis
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Monocytes from immunocompromised hosts containing
multiple morulae
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This monocyte has an intracytoplasmic vacuole
containing hyperchromatic and shrunken morula of
E. chaffeensis after the patient had received two
doses of doxycycline
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Modern Pathology 02/20/2004 doi10.1038/modpathol
.3800075 Characteristic peripheral blood findings
in human ehrlichiosis

• A relevant findings in this study was the
  presence of marked toxic change and prominent
  large granular lymphocytes in cases of
  ehrlichiosis.

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Modern Pathology 02/20/2004 doi10.1038/modpathol
.3800075 Characteristic peripheral blood findings
in human ehrlichiosis

• In this study, 38 of peripheral films from 16
  PCR-confirmed cases of ehrlichiosis had morulae
  in white blood cells.
• In immunocompromised patients, the level of
  detection by peripheral blood film examination
  was 100, whereas in immunocompetent patients,
  the level of detection was only 17.

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Sequencing of the 16S rRNA Gene The following
primers are used ECA and HE3 for the broad-range
assay, HE1 and HE3 for the E. chaffeensis assay,
EHR 521 and EHR 747 for the assay for the agent
of human granulocytic ehrlichiosis, and EWI and
HE3 for the E. ewingii assay.
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Clinical Infectious Diseases    20023422-27
The Serological Response of Patients Infected
with the Agent of Human Granulocytic Ehrlichiosis

• To characterize the serological response in
  humans to human granulocytic ehrlichiosis (HGE),
  152 patients were prospectively observed for as
  long as 42 months
• HGE was confirmed by detection of morulae in
  blood smears, polymerase chain reaction, blood
  culture, or a combination of these tests for 94
  patients (62.3), and 92 (97.8) of the patients
  had specific serum antibodies thereafter.

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Clinical Infectious Diseases    20023422-27
The Serological Response of Patients Infected
with the Agent of Human Granulocytic Ehrlichiosis

• One hundred twenty-six (99.2) of 127 patients
  tested at 1 month were seropositive (89 of 127
  patients had seroconversion),
• 150 (98.7) of the 152 patients had become
  seropositive by 6 months.
• Eleven patients (7.3) remained seropositive at
  42 months

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Geometric mean titers (GMTs) of antibodies to the
agent of (HGE) in serial serum sample.? Patients
in the early (treatment initiation) group,
patients in the late (treatment initiation)
group ?patients in the nontreated group.
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Percentages of patients who maintained serum
titers of antibody to the agent of human
granulocytic ehrlichiosis (HGE) of 80 during a
42-month period after the onset of HGE. ?
Patients in the early (treatment initiation)
group, patients in the late (treatment
initiation) group ?patients in the nontreated
group.
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Clinical Infectious Diseases    20023422-27
The Serological Response of Patients Infected
with the Agent of Human Granulocytic Ehrlichiosis

• Neither antibiotic therapy initiated during the
  first week of illness nor preexisting
  immunosuppressive conditions abrogated a
  serological response
• Indirect fluorescent antibody testing of
  acute-phase and convalescent-phase serum samples
  is a sensitive tool for laboratory confirmation
  of HGE.

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Treatment

• Doxycycline, 100 mg twice daily
• Tetracycline, 25 mg/kg/day in four equally
  divided doses
• Susceptibility testing of E. chaffeensis and the
  HGE agent in cell culture systems confirms that
  doxycycline and the rifamycins are ehrlichiacidal
  and reveals that chloramphenicol is not effective
  
• Treatment is continued until patient remains
  afebrilegt3days.

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Prevention

• At present, prevention of human ehrlichiosis must
  rely on avoidance of exposure to ticks, regular
  careful search of the body for ticks when
  exposure occurs, and prompt removal of ticks from
  the body