Human monocytic ehrlichiosis is a rare infectious disease caused by bacteria of the Ehrlichia family. Pathology can be manifested by a sharp increase in body temperature, headache, muscle pain (myalgia), chills, unexplained fatigue, weakness. Symptoms are observed several weeks after the initial infection. In addition, in many cases, laboratory tests reveal a decrease in the number of platelets in the circulating blood (thrombocytopenia) along with a decrease in the number of white blood cells (leukopenia) and an abnormal increase in certain liver enzymes (hepatic transaminases). In some cases, the symptoms progress and are expressed in nausea, vomiting, diarrhea, weight loss, loss of orientation in space. If a patient is diagnosed with human monocytic ehrlichiosis, treatment should immediately follow the diagnosis, since in the absence of adequate therapy, the disease leads to such dangerous complications as renal or respiratory failure. Ticks are carriers of the infection.
Signs and symptoms
Human monocytic ehrlichiosis, whose symptoms are easily confused with signs of other infectious diseases, was discovered and investigated relatively recently. As a rule, the pathology manifests itself approximately three weeks after the bite of a tick - a carrier of bacteria of the Ehrlichi family. Initially, patients suffer from typical signs of infection, including a sudden increase in body temperature and general weakness. In some cases, a skin rash is added to such symptoms. With a severe infection, the patient loses appetite, quickly loses weight and is at risk of anorexia. Occasionally, rarer signs of ehrlichiosis, such as cough, diarrhea, sore throat (pharyngitis), and abdominal pain, are also noted.
In most cases where human monocytic ehrlichiosis is suspected, diagnosis involves blood tests. The results of these examinations (a combination of leukocytopenia and thrombocytopenia along with an abnormal increase in the level of liver enzymes) allow the patient to make a correct diagnosis. In some cases, the patient also suffers from inflammation of the liver (hepatitis).
In the absence of adequate treatment, severe monocytic human ehrlichiosis develops. The symptoms of the disease at this stage differ from the standard manifestations of the infection and can be expressed in the following phenomena and conditions:
- difficulty breathing (shortness of breath, dyspnea);
- a bleeding disorder (coagulopathy) that can lead to bleeding in the gastrointestinal tract;
- neurologicaldisorders due to infection of the brain and spinal cord (central nervous system).
If the infection has spread to the central nervous system, a patient diagnosed with human monocytic ehrlichiosis has pathological tissue changes (tumors) in the brain. In addition, in some cases, meningitis develops - inflammation of the protective membrane membranes of the brain and spinal cord. The cerebrospinal fluid can also be affected by infection.
Neurological manifestations
Neurological symptoms of the disease include:
- loss of orientation in space;
- pathological sensitivity to light (photophobia);
- neck stiffness;
- episodes of uncontrolled electrical activity in the brain (seizures);
- coma.
- In rare cases observed:
- excessively intense reflex reactions (hyperreflexia);
- impaired coordination of voluntary movements (ataxia);
- partial loss of motor ability of facial muscles due to damage to one (or more) of the twelve pairs of nerves associated with the brain (cranial nerve palsy).
Monocytic ehrlichiosis and human granulocytic anaplasmosis, if left untreated, become life-threatening diseases.
Reasons
All types of analyzed pathology are caused by bacteria belonging to the Erlichia family. The causative agent of human monocytic ehrlichiosis is considered to be gram-negative.
It is believed that the main cause of infection is a tick bite. Some of these insects are carriers of pathogenic microbes.
Getting into the human body through the blood, Ehrlichi spread through the blood and lymphatic vessels. Lymph is a bodily fluid that carries cells designed to fight infectious diseases. Bacteria settle in certain cells (monocytes and macrophages) that play an invaluable role in maintaining the stable functioning of the immune system. These cells engulf and process microorganisms (a process called phagocytosis), including bacteria and other foreign elements. However, erlichia penetrate deep into the natural defenders of immunity and begin to grow in vacuoles - cavities surrounded by a membrane. The disease affects not only monocytes and macrophages in the blood, but also certain types of bodily tissues (including bone marrow, lymph nodes, liver, spleen, kidneys, lungs, and cerebrospinal fluid).
Differential diagnosis: granulocytic anaplasmosis
The symptoms of this infectious disease can be easily confused with signs of other pathologies. The most common differential diagnoses are monocytic ehrlichiosis and human granulocytic anaplasmosis.
Unlike MEC, granulocytic anaplasmosis is caused by a bacterium, appropriately named anaplasma. The microorganism carried by ticks infects certain granular white blood cells - neutrophil granulocytes. Thesecells are involved in the process of phagocytosis and are usually responsible for the destruction of harmful microbes. When infected with anaplasma, typical symptoms usually appear a week after being bitten by a tick that carries the bacteria. Almost always, the patient suffers from fever, chills, muscle pain (myalgia), general weakness, fatigue, headache. Sometimes there is also coughing, vomiting and / or loss of orientation in space. In addition, granulocytic anaplasmosis is similar to an infection such as human monocytic ehrlichiosis, also in that the results of blood tests equally reveal an increase in certain liver enzymes (hepatic transaminase). Often, anemia is also diagnosed, caused by a pathological decrease in the level of red cells in the circulating blood. In the absence of proper treatment, there is a risk of developing renal failure. In the US, cases of human granulocytic anaplasmosis are most commonly reported in the northeastern and western states.
Sennetsu Fever
Human monocytic ehrlichiosis (HEM) must also be distinguished from sennetsu fever, an extremely poorly understood and very rare infectious disease belonging to the human ehrlichiosis subtype and caused by bacteria with the corresponding name - sennetsu erlichia. A few weeks after the initial infection, symptoms develop that are similar to the common signs of MEC: a sharp increase in body temperature, headache, muscle pain (myalgia). Some patients experiencenausea, vomiting or loss of appetite up to anorexia. In addition, the results of blood tests can indicate a decrease in the level of white blood cells (leukopenia) and an abnormal increase in liver enzymes. The carrier (or carrier) of sennetsu fever has not yet been definitely identified; some scientists suggest that it may be Ixodes ticks, while other researchers argue that this disease can be contracted after eating raw fish. So far, cases have only been reported in eastern Japan and Malaysia.
Lyme borreliosis
Lyme borreliosis is an infectious disease caused by spirochete bacteria from the Borrelia family. Carriers of harmful microbes are black-legged ticks. In most cases, this disease is primarily manifested by the appearance of a red tumor on the skin, which at first outwardly resembles a small raised round spot (papule). The papule begins to grow rapidly and eventually reaches at least five centimeters in diameter. After this, symptoms appear that also characterize human monocytic ehrlichiosis. The likelihood of contracting Lyme borreliosis is much lower than the risk of catching MEC, but differential diagnosis remains a necessary step in determining infection. Patients with Lyme borreliosis also often complain of fever (not as sharp and dangerous as with MEC), chills, muscle and headaches, weakness, fatigue, and pain or stiffness in large joints (infectious arthritis), most often in knees. Symptomsmay take the form of recurrent cycles. In severe cases, in the absence of timely treatment, neurological disorders and pathologies of the heart muscle are observed. According to statistics, most often Lyme borreliosis is found in the northeastern states of the United States. However, cases of infection are also known in other countries, including China, Japan, Australia and some European countries.
Human piroplasmosis
Human monocytic ehrlichiosis, which is relatively more likely to be infected than other bacteria, is not the only potentially dangerous infectious disease carried by ticks. Human piroplasmosis (in other terminology - babesiosis) is an infection caused by unicellular microorganisms from the Babesia family. Most often, this disease affects animals, but from time to time there are cases of human infection with it. In particular, it is believed that ixodid ticks are carriers of babesia that can parasitize on the human body. Piroplasmosis is similar to human monocytic ehrlichiosis primarily in terms of symptoms: patients complain of fever, chills, headaches and muscle pain, nausea, and vomiting. In addition, pathological phenomena such as premature destruction of red cells in the circulating blood (hemolytic anemia), an abnormal decrease in their number (thrombocytopenia), a decrease in the total volume of white blood cells (leukopenia) and an enlargement of the spleen (splenomegaly) are observed. In people in generally good he alth, symptomsdiseases may be mild or absent altogether. Severe cases of human piroplasmosis are seen in patients who have previously had surgery to remove the spleen (splenectomy) or who have a weak immune system. Most often, human babesiosis is diagnosed in the northern United States, but cases of its detection in European countries are also known.
American tick-borne rickettsiosis
Human monocytic ehrlichiosis must be distinguished from American tick-borne rickettsiosis, a rare infectious disease caused by bacteria from the Rickettsia family. The carriers of the infection are the same insects that can infect humans with monocytic ehrlichiosis. With rickettsiosis, severe headaches and muscle pains, fever, chills, loss of orientation in space are observed. In most cases, two to six days after a tick bite, a skin rash appears, primarily affecting the palms, wrists, soles of the feet, ankles, and forearms. Later, the rash spreads to the face, trunk and legs. Nausea, vomiting and abdominal pain are sometimes observed. In some cases, when the disease is not diagnosed on time or in the absence of adequate treatment, the symptoms of American tick-borne rickettsiosis can be life-threatening. Epidemic outbreaks of this disease are recorded in various regions of the United States.
Diagnosis
Human monocytic ehrlichiosis, which can cause potentially dangerous symptoms, should be diagnosed with a thorough medicalexamination, analysis of signs of the disease and specialized laboratory tests. Blood tests often indicate typical manifestations of human monocytic ehrlichiosis: a decrease in the volume of red blood cells (thrombocytopenia), a decrease in the number of certain white cells (leukopenia), and a simultaneous increase in the level of certain liver enzymes (for example, serum aspartate aminotransferase and alanine aminotransferase). In some cases, as a result of laboratory examinations, pathologies of the cerebrospinal fluid are detected. In addition, a chest x-ray may reveal abnormal changes in the lungs (such as pulmonary infiltrates or fluid accumulations).
Examination of a blood smear under an electron beam microscope can detect accumulations of bacteria in the vacuoles of some cells (in particular, monocytes), but such accumulations are not always visible at an early stage of an infectious disease. In some cases, additional specialized laboratory tests are required to determine the specific type of infection or confirm the diagnosis.
Such specialized tests include, for example, an indirect immunofluorescent method for detecting pathologies, which consists in the study of serum produced on the basis of the patient's blood. Antibodies - proteins produced by certain white blood cells - help the body fight off toxins and harmful microorganisms. When using the indirect immunofluorescence method, human antibodies are labeled with special fluorescentdyes, put the serum under ultraviolet light and examine it under a microscope to detect antibody responses to specific microorganisms.
Treatment
If the diagnosis of human monocytic ehrlichiosis is confirmed, how to treat this disease? Most often, doctors prescribe a standard dosage of tetracycline antibiotics. Alternatively, doxycycline-based therapy is sometimes used. In severe cases, the patient may need professional supervision in a hospital setting. In addition to antibiotics, you can take any medicine approved by your doctor to relieve typical symptoms of the infection.
Prevention
If you live in a geographic area where ticks of potentially dangerous species, including the Ehrlichia family of bacteria, are present, it is advisable to take appropriate precautions. If you go out into nature, remember that you thereby increase the risk of contracting such a serious disease as human monocytic ehrlichiosis. A photo of ticks, which are confirmed carriers of bacteria, will help you stay vigilant, but knowing a potential enemy in person is not enough. Wear long pants, shirts and long-sleeved T-shirts. It is important to wear hats, wide-brimmed hats are best, as many mites live in trees. Choose light-colored clothing, as it is easiest to see the insect on it. Use special repellents and always as often as possibleinspect skin and clothing. Most tick bites occur on the scalp and neck.
