PEDIATRICS Vol. 106 No. 3 September 2000, pp. 602-604

EXPERIENCE AND REASON:
Human Granulocytic Ehrlichiosis Presenting as Abdominal Pain

	ABSTRACT

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Human granulocytic ehrlichiosis (HGE) is an emerging infectious disease that primarily affects adults. Typical clinical features include fever, headache, and myalgias. This case represents the youngest reported patient with HGE. Her clinical presentation was unusual in that she presented with severe abdominal pain. In addition, she did not develop the typical spectrum of laboratory abnormalities that has been reported in adults. This patient's course suggests that the presentation of HGE may be more varied than previously reported.

Human granulocytic ehrlichiosis (HGE) is an emerging infectious disease caused by an organism closely related or identical to Ehrlichia equi and E phagocytophilia.^1,2 In the northeastern United States the organism is transmitted by the deer tick, Ixodes scapularis, which is the same vector that transmits the cause of Lyme disease, Borrelia burgdorferi. In contrast to Lyme disease, however, HGE is rare in patients <20 years old and most cases occur in males.³ Clinical features of the illness include fever, headache, and myalgias, although there are no consistent physical findings.^4-6 Laboratory hallmarks are neutropenia, thrombocytopenia, and mildly elevated liver transaminases.

The diagnosis of HGE can be confirmed by finding cytoplasmic inclusion bodies (morulae) in granulocytes on a Wright-stained blood smear. Typically, morulae are found in 1% to 6% of granulocytes,¹ although a sensitivity as high as 80% has been reported.⁶ Polymerase chain reaction (PCR) to the 16S rDNA sequence has been shown to be rapid, sensitive (86%), and specific (100%).⁷ However, PCR testing is not widely available. At the present time, the diagnosis of HGE is most often confirmed by either a fourfold rise between acute and convalescent sera in the indirect fluorescent antibody (IFA) titer to E equi or a single titer 1:80.⁸

The following case is a very young patient with HGE who had an unusual presentation with acute abdominal pain.

	CASE REPORT

A 5-year-old girl presented to the emergency department with a 2-week history of fever and a 2-day history of abdominal pain. There was no vomiting or diarrhea. Another physician had begun treating her with amoxicillin 1 week before for presumptive Lyme disease. There was no history of a tick bite or erythema migrans and her Lyme antibody titers obtained at that time were subsequently reported to be negative. In the emergency department her physical examination was notable for a temperature of 103°F and right lower quadrant tenderness on deep abdominal palpation. Laboratory results included a normal urinalysis, a hemoglobin of 11.2 g/dL, a hematocrit of 32%, a white blood count of 13 400/mm³ (59% neutrophils, 7% bands, 26% lymphocytes with rare atypical forms, 7% monocytes, and 1% eosinophils), and a platelet count of 287 000/mm³. A blood culture was obtained. The pain resolved without treatment and she was discharged.

She returned to the emergency department about 12 hours later with a temperature of 103.6°F, pallor, abdominal distension, and diffuse abdominal tenderness. A repeat complete blood count was significant for a hemoglobin of 9.1 g/dL, a hematocrit of 27%, a white blood cell count of 8000/mm³ (59% neutrophils, 5% bands, 26% lymphocytes, and 10% monocytes), and a platelet count of 278 000/mm³. The serum electrolytes, prothrombin time, partial thromboplastin time, and a urinalysis were all normal. The aspartate aminotransferase (AST) was minimally elevated (42 U/L), but the alanine aminotransferase (ALT) was normal (36 U/L). Abdominal radiographs and a computed tomography (CT) scan of the abdomen with intravenous contrast were significant for mild hepatosplenomegaly. In view of the persistent high fever, specimens were obtained for serum antibodies to B burgdorferi, E chaffeensis, and the HGE agent, as well as for PCR testing for the 2 causative agents of human ehrlichiosis. The patient was admitted to the hospital.

The next day, the white blood cell count was 8900/mm³ (68% neutrophils, 26% lymphocytes, and 6% monocytes), the platelet count was 298 000/mm³, and an abdominal ultrasound revealed fluid-filled loops of bowel in the right lower quadrant without any free fluid. Intravenous ceftriaxone therapy was initiated. On the third hospital, day the fever, abdominal pain, and distension persisted, and guarding and rebound were noted on abdominal palpation. A repeat abdominal CT scan with oral contrast showed distended loops of small and large bowel without any masses or free fluid. In view of a concern about a possible perforated appendix, an exploratory laparotomy was performed. At surgery, mild nonspecific serositis of the vermiform appendix was found along with a 7-mm lymph node, which subsequently was reported to show nonspecific reactive changes. Postoperatively, her electrolytes and liver function tests were normal (AST: 38 U/L; ALT: 31 U/L), but the white blood cell count had decreased to 3600/mm³ (69% neutrophils, 29% lymphocytes, and 2% monocytes) and the platelet count was 195 000/mm³. The following day (hospital day 4), the New York State Department of Health laboratory reported that the PCR was positive for the presence of HGE agent 16s rDNA and negative for E chaffeensis. Treatment with doxycycline was started and the patient was afebrile the next day.

Subsequently, the acute polyclonal IFA for E equi was reported as nonspecific, but a convalescent specimen obtained 23 days later was positive, with a titer of 320. Four months after the hospitalization the patient was well. At that time her IFA for E equi immunoglobulin G (IgG) was positive (1:512), but the immunoglobulin M (IgM) was negative (<1:20). Both IgG and IgM IFA titers for E chaffeensis were negative.

	DISCUSSION

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This case has several unusual features. First, to our knowledge, this the youngest patient reported with documented HGE.^4,5 The diagnosis was confirmed by the elevated IFA to E equi, the positive PCR for the HGE agent, and the increase in IFA E equi IgG titer between the acute and convalescent specimens. The vast majority of cases of HGE have been reported in adults, with very few diagnosed during the first 2 decades of life. This is in sharp contrast to Lyme disease, in which the incidence is much higher in children than adults. There is no clear explanation for this age discrepancy, despite the fact that the same vector spreads the agents that cause both HGE and Lyme disease.

Second, although many of the patient's symptoms were typical for HGE, there have been no previous reports of HGE mimicking acute abdominal pain in any age patient. In fact abdominal symptoms are unusual, although Wallace et al⁵ did report 3 patients with gastrointestinal hemorrhages.

Finally, our patient did not manifest the spectrum of laboratory abnormalities typically seen in adults with HGE.⁶ She did have leukopenia, but her platelet count remained normal and she had only a minimal, transient increase in her AST. Once other young patients with HGE are reported, it will be interesting to see whether the clinical presentations are different in children and whether they develop the characteristic laboratory abnormalities noted in older patients. If HGE is suspected, prompt treatment with doxycycline is indicated, pending laboratory confirmation.^9,10

Jeffrey C. Gershel, MD
Department of Pediatrics
Jacobi Medical Center
Albert Einstein College of Medicine
Bronx, NY 10461

	FOOTNOTES

Received for publication Oct 4, 1999; accepted Jan 27, 2000.

Address correspondence to Jeffrey C. Gershel, MD, Department of Pediatrics, Jacobi Medical Center, Room 817, 1400 Pelham Pkwy S, Bronx, NY 10461. E-mail: zinc4{at}aol.com

	ABBREVIATIONS

HGE, human granulocytic ehrlichiosis; PCR, polymerase chain reaction; IFA, indirect fluorescent antibody; AST, aspartate aminotransferase; ALT, alanine aminotransferase; CT, computed tomography (scan); IgG, immunoglobulin G; IgM, immunoglobulin M.

	REFERENCES

Top Abstract Introduction Discussion References

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