Human monocytotropic ehrlichiosis

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Human monocytic ehrlichiosis
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Ehrlichia chaffeensis
Specialty Infectious disease   Blue pencil.svg

Human monocytotropic ehrlichiosis [1] (HME) is a form of ehrlichiosis associated with Ehrlichia chaffeensis . [2] This bacterium is an obligate intracellular pathogen affecting monocytes and macrophages.

Ehrlichiosis is a tickborne bacterial infection, caused by bacteria of the family Anaplasmataceae, genera Ehrlichia and Anaplasma. These obligate intracellular bacteria infect and kill white blood cells.

Ehrlichia chaffeensis is an obligate intracellular gram-negative species of rickettsiales bacteria. It is a zoonotic pathogen transmitted to humans by the lone star tick. It is the causative agent of human monocytic ehrlichiosis.

Contents

Symptoms

The most common symptoms are fever, headache, malaise, and muscle aches (myalgia). Compared to human granulocytic ehrlichiosis, rash is more common. [3] Laboratory abnormalities include thrombocytopenia, leukopenia, and elevated liver tests.

Fever common medical sign characterized by elevated body temperature

Fever, also known as pyrexia and febrile response, is defined as having a temperature above the normal range due to an increase in the body's temperature set point. There is not a single agreed-upon upper limit for normal temperature with sources using values between 37.5 and 38.3 °C. The increase in set point triggers increased muscle contractions and causes a feeling of cold. This results in greater heat production and efforts to conserve heat. When the set point temperature returns to normal, a person feels hot, becomes flushed, and may begin to sweat. Rarely a fever may trigger a febrile seizure. This is more common in young children. Fevers do not typically go higher than 41 to 42 °C.

Headache pain in the head or neck

Headache is the symptom of pain anywhere in the region of the head or neck. It occurs in migraines, tension-type headaches, and cluster headaches. Frequent headaches can affect relationships and employment. There is also an increased risk of depression in those with severe headaches.

Myalgia, or muscle pain, is a symptom of many diseases and disorders. The most common causes are the overuse or over-stretching of a muscle or group of muscles. Myalgia without a traumatic history is often due to viral infections. Longer-term myalgias may be indicative of a metabolic myopathy, some nutritional deficiencies or chronic fatigue syndrome.

The severity of the illness can range from minor or asymptomatic to life-threatening. CNS involvement may occur. A serious septic or toxic shock-like picture can also develop, especially in patients with impaired immunity. [4]

Cause

This disease is known to be caused by tick bites.

Diagnosis

Tick exposure is often overlooked. For patients living in high-prevalence areas who spend time outdoors, a high degree of clinical suspicion should be employed.

Ehrlichia serologies can be negative in the acute period. PCR is therefore the laboratory diagnostic tool of choice. [5]

Treatment

If ehrlichiosis is suspected, treatment should not be delayed while waiting for a definitive laboratory confirmation, as prompt doxycycline therapy has been associated with improved outcomes. [6] Doxycycline is the treatment of choice.

Doxycycline chemical compound

Doxycycline is an antibiotic that is used in the treatment of infections caused by bacteria and certain other parasites. It is used to treat bacterial pneumonia, acne, chlamydia infections, early Lyme disease, cholera, and syphilis. It is also used to prevent malaria and in combination with quinine, to treat malaria. Doxycycline can be used either by mouth or by injection into a vein.

Presentation during early pregnancy can complicate treatment. [7] Rifampin has been used in pregnancy and in patients allergic to doxycycline. [8]

Epidemiology

In the USA, HME occurs across the south-central, southeastern, and mid-Atlantic states, regions where both the white-tailed deer (Odocoileus virginianus) and lone star ticks (Amblyomma americanum) thrive.

HME occurs in California in Ixodes pacificus ticks and in Dermacentor variabilis ticks. [9] Nearly 600 cases were reported to the CDC in 2006. In 2001–2002, the incidence was highest in Missouri, Tennessee, and Oklahoma, as well as in people older than 60. [10]

See also

Related Research Articles

Ehrlichiosis (; also known as canine rickettsiosis, canine hemorrhagic fever, canine typhus, tracker dog disease, and tropical canine pancytopenia is a tick-borne disease of dogs usually caused by the organism Ehrlichia canis. Ehrlichia canis is the pathogen of animals. Humans can become infected by E. canis and other species after tick exposure. German Shepherd Dogs are thought to be susceptible to a particularly severe form of the disease, other breeds generally have milder clinical signs. Cats can also be infected.

Rifampicin pharmaceutical drug

Rifampicin, also known as rifampin, is an antibiotic used to treat several types of bacterial infections, including tuberculosis, Mycobacterium avium complex, leprosy, and Legionnaires’ disease. It is almost always used together with other antibiotics, except when given to prevent Haemophilus influenzae type b and meningococcal disease in people who have been exposed to those bacteria. Before treating a person for a long period of time, measurements of liver enzymes and blood counts are recommended. Rifampicin may be given either by mouth or intravenously.

Tick-borne diseases, which afflict humans and other animals, are caused by infectious agents transmitted by tick bites. Tick-borne illnesses are caused by infection with a variety of pathogens, including rickettsia and other types of bacteria, viruses, and protozoa. Because individual ticks can harbor more than one disease-causing agent, patients can be infected with more than one pathogen at the same time, compounding the difficulty in diagnosis and treatment. As of 2016, 16 tick-borne diseases of humans are known.

Erythema migrans

Erythema migrans refers to a rash often seen in the early stage of Lyme disease, and can also be caused by southern tick-associated rash illness (STARI). It can appear anywhere from one day to one month after a tick bite. This rash does not represent an allergic reaction to the bite, but rather an actual skin infection of one of the Lyme bacteria species from the genus Borrelia.

<i>Dermacentor variabilis</i> species of arachnid

Dermacentor variabilis, also known as the American dog tick or wood tick, is a species of tick that is known to carry bacteria responsible for several diseases in humans, including Rocky Mountain spotted fever and tularemia. It is one of the most well-known hard ticks. Diseases are spread when it sucks blood from the host, which could take several days for the host to experience some symptoms.

A canine vector-borne disease (CVBD) is one of "a group of globally distributed and rapidly spreading illnesses that are caused by a range of pathogens transmitted by arthropods including ticks, fleas, mosquitoes and phlebotomine sandflies." CVBDs are important in the fields of veterinary medicine, animal welfare, and public health. Some CVBDs are of zoonotic concern.

<i>Anaplasma phagocytophilum</i> species of bacterium

Anaplasma phagocytophilum is a Gram-negative bacterium that is unusual in its tropism to neutrophils. It causes anaplasmosis in sheep and cattle, also known as tick-borne fever and pasture fever, and also causes the zoonotic disease human granulocytic anaplasmosis.

Anaplasmosis disease, mostly animal, caused by bacteria of the genus Anaplasma

Anaplasmosis is a disease caused by a rickettsial parasite of ruminants, Anaplasma spp and is therefore related to rickettsial disease. The microorganisms are Gram-negative, and infect red blood cells. They are transmitted by natural means through a number of haematophagous species of ticks. The Ixodes tick that commonly transmits Lyme disease also spreads anaplasmosis.

Anaplasma is a genus of bacteria of the alphaproteobacterial Order Rickettsiales, Family Anaplasmataceae.

<i>Ixodes scapularis</i> parasit ixodes scapularis

Ixodes scapularis is commonly known as the deer tick or black-legged tick, and in some parts of the US as the bear tick. It is a hard-bodied tick of the eastern and northern Midwestern United States and southeastern Canada. It is a vector for several diseases of animals, including humans and is known as the deer tick owing to its habit of parasitizing the white-tailed deer. It is also known to parasitize mice, lizards, migratory birds, etc. especially while the tick is in the larval or nymphal stage.

<i>Amblyomma americanum</i> species of arachnid

Amblyomma americanum, also known as the lone star tick, the northeastern water tick, or the turkey tick, is a type of tick indigenous to much of the eastern United States and Mexico, that bites painlessly and commonly goes unnoticed, remaining attached to its host for as long as seven days until it is fully engorged with blood. It is a member of the phylum Arthropoda, class Arachnida. The adult lone star tick is sexually dimorphic, named for a silvery-white, star-shaped spot or "lone star" present near the center of the posterior portion of the adult female shield (scutum); adult males conversely have varied white streaks or spots around the margins of their shields.

Ehrlichia ewingii is a species of rickettsiales bacteria. It has recently been associated with human infection, and can be detected via PCR serological testing. The name Ehrlichia ewingii was proposed in 1992.

Human granulocytic anaplasmosis human disease

Human granulocytic anaplasmosis (HGA) is a tick-borne, infectious disease caused by Anaplasma phagocytophilum, an obligate intracellular bacterium that is typically transmitted to humans by ticks of the Ixodes ricinus species complex, including Ixodes scapularis and Ixodes pacificus in North America. These ticks also transmit Lyme disease and other tick-borne diseases.

Ehrlichiosis ewingii infection is an infectious disease caused by an intracellular bacteria, Ehrlichia ewingii. The infection is transmitted to humans by the tick, Amblyomma americanum. This tick can also transmit Ehrlichia chaffeensis, the bacteria that causes human monocytic ehrlichiosis (HME).

Ehrlichia canis is an obligate, intracellular bacterium that acts as the causative agent of Ehrlichiosis, a disease most commonly affecting canine species. This pathogen is present throughout the United States, South America, Asia, and Africa. First defined in 1935, E. canis emerged in the United States in 1963 and its presence has since been found in all 48 contiguous United States. Reported primarily in dogs, E. canis has also been documented in felines and humans where it is transferred most commonly via Rhipicephalus sanguineus, the brown dog tick.

Ehrlichia Wisconsin HM543746 is an unnamed tick bacterium that spread through Minnesota and Wisconsin in 2009 and is similar to Ehrlichia muris.

In USA, the National Notifiable Disease Surveillance System (NNDSS) is responsible for sharing information regarding notifiable diseases. As of 2017, the following are the notifiable diseases in United States of America as mandated by the Centers for Disease Control and Prevention :

References

  1. Rapini, Ronald P.; Bolognia, Jean L.; Jorizzo, Joseph L. (2007). Dermatology. Mosby. p. 1130. ISBN   978-1-4160-2999-1.
  2. Schutze GE, Buckingham SC, Marshall GS, et al. (June 2007). "Human monocytic ehrlichiosis in children". Pediatr. Infect. Dis. J. 26 (6): 475–9. doi:10.1097/INF.0b013e318042b66c. PMID   17529862.
  3. Dumler JS, Choi KS, Garcia-Garcia JC, et al. (December 2005). "Human granulocytic anaplasmosis and Anaplasma phagocytophilum". Emerging Infectious Diseases. 11 (12): 1828–34. doi:10.3201/eid1112.050898. PMC   3367650 . PMID   16485466.
  4. Paddock CD, Folk SM, Shore GM, et al. (November 2001). "Infections with Ehrlichia chaffeensis and Ehrlichia ewingii in persons coinfected with human immunodeficiency virus". Clinical Infectious Diseases. 33 (9): 1586–94. doi:10.1086/323981. PMID   11568857.
  5. Prince LK, Shah AA, Martinez LJ, Moran KA (August 2007). "Ehrlichiosis: making the diagnosis in the acute setting". Southern Medical Journal. 100 (8): 825–8. doi:10.1097/smj.0b013e31804aa1ad. PMID   17713310.
  6. Hamburg BJ, Storch GA, Micek ST, Kollef MH (March 2008). "The importance of early treatment with doxycycline in human ehrlichiosis". Medicine. 87 (2): 53–60. doi:10.1097/MD.0b013e318168da1d. PMID   18344803.
  7. Muffly T, McCormick TC, Cook C, Wall J (2008). "Human granulocytic ehrlichiosis complicating early pregnancy". Infect Dis Obstet Gynecol. 2008: 1–3. doi:10.1155/2008/359172. PMC   2396214 . PMID   18509484.
  8. Krause PJ, Corrow CL, Bakken JS (September 2003). "Successful treatment of human granulocytic ehrlichiosis in children using rifampin". Pediatrics. 112 (3 Pt 1): e252–3. doi:10.1542/peds.112.3.e252. PMID   12949322.
  9. Holden K, Boothby JT, Anand S, Massung RF (July 2003). "Detection of Borrelia burgdorferi, Ehrlichia chaffeensis, and Anaplasma phagocytophilum in ticks (Acari: Ixodidae) from a coastal region of California". J. Med. Entomol. 40 (4): 534–9. doi:10.1603/0022-2585-40.4.534. PMID   14680123.
  10. "Statistics and Epidemiology: Annual Cases of Ehrlichiosis in the United States". Ehrlichiosis. Division of Vector-Borne Diseases (DVBD), National Center for Emerging and Zoonotic Infectious Diseases (NCEZID), Centers for Disease Control and Prevention. 5 September 2013.
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