Case Study by Joshua Hagood , BS ; Rashmi Verma , MD , FACP
Human Monocytotropic Ehrlichiosis in Immunocompromised Patient
Introduction Human monocytic ehrlichiosis ( HME ) is a potentially life-threatening tick-borne rickettsial disease ( TBRD ) caused by the obligate intracellular gram-negative bacteria , Ehrlichia chaffeenis . Fatal HME presents with acute ailments of sepsis and toxic shock-like symptoms that can evolve to multi-organ failure and death . The most common clinical symptoms are fever , headache , myalgias , and arthralgias . Rash can also be seen more commonly in pediatric cases . Although most known HME cases are not fatal , approximately 3 – 5 % of all Ehrlichia infections in the U . S . result in death despite patients receiving appropriate care . 5 The characteristic lab findings include significantly lowered total white blood cells , neutrophils , and platelets along with mildly elevated transaminases . 1 The first-line treatment for HME are tetracyclines and their derivatives , particularly doxycycline . Typically , patients treated with doxycycline are afebrile within one to three days after initiation . 2 Alternatively , rifampin has been shown to have rapid bactericidal effects in vitro and several reports have shown successful treatment with chloramphenicol . 2
Case Report Our patient is a 50-year-old female undergoing chemotherapy treatment consisting of fluorouracil ( 5-FU ) and mitomycin for squamous cell carcinoma of the anal canal . She presented to the emergency department after experiencing two weeks of fatigue , shortness of breath , and cough , which was initially dry and subsequently became productive . The patient also reported diffuse body aches and reported a temperature of 39.4 ° C . The patient was also an active smoker , with an average of one pack per day for 30 years .
On arrival to the ED , physical exam was significant for tachycardia and crackles in the lower lobe of the left lung . She had a temperature of 37.3 C , heart rate of over 100 beats per minute , blood pressure of 130 / 90mmHg , and oxygen saturation of 97.5 %. Lab values showed white cell count of 5.6K / ul with 76.5 % neutrophils , ANC of 4.29K / ul , hemoglobin of 12g / dl , platelet count of 179K /µ l , sodium of 131mmol / L , and potassium of 4.1mmol / L . Chest x-ray revealed left basilar atelectasis , and CT revealed interstitial pulmonary edema . The patient was given vancomycin and cefepime and admitted for treatment of presumed pneumonia . Upon admission , the patient was started on ceftriaxone and azithromycin .
Twenty-four hours after admission , the patient ’ s shortness of breath persisted and she began spiking temperatures as high as 39.2 C . Blood pressure dropped to 103 / 42mmHg and heart rate was measured at 110 beats per minute . Repeat laboratory values showed that her potassium had dropped to 2.6mmol / L and her calcium had dropped to 6.1mg / dl . Liver function tests showed elevated alkaline phosphatase of 108 IU / L and aspartate aminotransferase of 51 IU / L along with lower albumin of 2.2g / dl . Blood labs with manual differential showed total white cell count of 2.73 k / ul with absolute neutrophil count of 0.9 k / ul . Blood cultures reported no growth at 24 hours . A more detailed history elicited that she had discovered a tick on her waistline while showering the week before . The patient was then switched to a regiment of vancomycin , cefepime , and doxycycline while awaiting the results of a tick panel that included PCR detection tests for Anaplasma and multiple Ehrlichia species .
Within 24 hours of starting the doxycycline , the patient ’ s fever , cough , and shortness of breath had subsided , and lungs were clear to auscultation on exam . PCR tests returned positive for Ehrlichia chaffeensis . The patient ’ s WBCs and platelets continued to drop . Forty-eight hours after initiation of doxycycline , her WBC was measured at 2.31K / ul and platelets were measured at 52K / ul . Due to the drastic clinical improvement , the patient was discharged four days after admission with instructions to continue doxycycline P . O . for a total 10-day course .
Discussion Pathogenic rickettsiae and ehrlichiae are likely emerging diseases that cause under-recognized presentations , so clinicians must be aware of this disease in order to make a timely and appropriate diagnosis . The number of cases of Ehrlichia chaffeensis infections reported to the CDC has been on the rise . Between the years 2000 and 2017 , the number of reported cases has increased eight-fold from 200 cases in 2000 to 1642 cases in 2017.3 Knowledge of the presentation and treatment of HME is especially useful for physicians practicing in Arkansas , as the disease is most commonly seen in the southern central states . Over 50 % of reported cases come from only four states ( Arkansas , Missouri , Virginia , and New York ). 3 HME could be related to individuals engaging in outdoor occupations and / or living in close proximity to areas that favor tick habitats . It is very likely that endemic regions in the U . S . are affected by a combination of factors including climate , land use , and socio-economic conditions . Given the prevalence of Ehrlichiosis in Arkansas , physicians can mitigate risk of contraction by counseling their patients on preventative measures against tick
94 • The Journal of the Arkansas Medical Society www . ArkMed . org