What Is Black Fever?

Black fever, also known as visceral leishmaniasis, is a chronic endemic infectious disease caused by Leishmania donovani (black fever protozoa). It used to be popular in areas north of the Yangtze River. Sources of infection are patients and sick dogs (), which are transmitted through white pheasants. From May to August every year is the active season of Amaranth. When Amaranth sucks the patient's blood, the protozoan enters the Amaranth and develops into a flagellum. After 7 days, the Amaranth again injects the flagellum, which can cause infection. Protozoa are mainly parasitic in patients' blood, liver, spleen, bone marrow, and lymph nodes.

Basic Information

nickname: Visceral Leishmaniasis
English name: kala-azar
Visiting department: Infectious Diseases

Common symptoms: Irregular fever, weight loss, enlarged liver and spleen,
Contagious: Have
way for spreading: White pheasant spread

Causes of black fever

When the infected white sturgeon bites a person, the preflagellate is injected into the subcutaneous tissue, and a small part of it is damaged by the neutrophil slope, and most of it is engulfed by macrophages of the reticuloendothelial system and reproduces and proliferates in it. Throughout the body, the macrophages are destroyed and swallowed by other monocytes-macrophages. Repeatedly, the body's mononuclear-macrophages proliferate in large numbers, mainly by damage to the liver, spleen, bone marrow, and lymph nodes. Cell proliferation and secondary obstructive congestion are the basic causes of hepatosplenomegaly and lymphadenopathy. Due to the decrease of granulocytes and immune-active cells, the body's immune function is low, and it is easy to cause secondary infection. Due to the continuous proliferation of the reticuloendothelial system and the large increase in plasma cells, the increase in plasma globulin, coupled with the decrease in the synthesis of albumin in the liver, caused the plasma albumin ratio to be inverted.

Clinical manifestations of black fever

Incubation period-generally 3 to 6 months, the shortest is only about 10 days, and the longest is 9 years.

Typical clinical manifestations

(1) The onset is usually slow, irregular fever, bimodal fever, mild symptoms of poisoning, gastrointestinal symptoms such as loss of appetite, abdominal pain and diarrhea from the beginning. May have similar cold-like symptoms. The course of the disease is long and can reach several months. The symptoms of systemic poisoning are not obvious. Some patients can still work after having fever for several months.

(2) Splenomegaly, liver, and lymph nodes are enlarged. The spleen is swollen obviously. It can be touched and soft for half a month after the onset, and then gradually increase. After half a year, it can reach the umbilicus and even the pelvic cavity. The texture is hard. The liver was mild to moderately swollen, with a soft texture; occasionally jaundice and ascites. Lymph nodes are mild to moderately enlarged.

(3) Anemia and malnutrition can occur in the later stages of the disease, including atrophy, thinning hair, palpitations, shortness of breath, pale complexion, edema, and rough skin. The skin color can be deepened, so it is called black fever (kala-azar means Hindi fever, Dark skin). There may be nosebleeds, gum bleeding and skin bleeding points due to thrombocytopenia.
Symptom relief and exacerbation can occur alternately during the course of the disease. Generally, one month after the illness enters the remission phase, the temperature drops, the symptoms ease, and the spleen shrinks for several weeks. It can recur later, and the course of the disease can be delayed for several months.

2. Special clinical types

(1) Most patients with cutaneous black fever have a history of black fever, which can occur during the course of black fever, and a few are primary patients without a history of black fever. The skin lesions are mainly nodules, pimples, and erythema, with occasional discolored spots, smooth surfaces, and rarely self-healing without ulceration. Nodules can be connected to form a tumor-like leprosy. Occurs on any part of the body, but is more common on the cheeks. Patients are generally in good condition, most of them can work and work as usual, and the course of disease can be as long as 10 years.

(2) Lymph node type black fever is rare, mainly in infants and young children. There is no history of black fever, which can occur simultaneously with black fever. Presented as superficial lymphadenopathy, especially in the groin area, the size of peanuts, can also be fused into a large block, shallow and mobile, no local swelling and pain. The general condition is good, and the liver and spleen are not enlarged or slightly enlarged.

Black fever check

Puncture check

(1) Smear method: Smear, stain and microscopic examination with bone marrow puncture. This method is the most commonly used, with a detection rate of 80% to 90%. Superficial and swollen lymph nodes should be selected, and the detection rate is 46% to 87%. Lymph node biopsy can also be done. The detection rate of splenic puncture is high, which can reach 90.6% -99.3%, but it is unsafe and less used.

(2) Cultivation method The above-mentioned puncture is inoculated into NNN medium, and placed in an incubator at 22-25 ° C. After one week, if the active preflagellate was found in the culture, it was judged as a positive result. Handling and culturing should be strictly aseptic.

(3) Animal inoculation method The puncture is inoculated to susceptible animals (such as hamsters, BALB / c mice, etc.), and liver and spleen are used as prints or smears after 1 to 2 months. Check.

2. Skin biopsy

Pierce the skin with a sterile needle at the skin nodule, take a little tissue fluid, or use a scalpel to randomly take a little tissue for smears, staining, and microscopy.

Black fever diagnosis

Immunodiagnosis

(1) Detection of serum antibodies such as enzyme-linked immunosorbent assay, indirect hemagglutination test, convection immunoelectrophoresis, indirect fluorescence test, direct agglutination test, etc., has a high positive rate and a high false positive rate. In recent years, pure antigens have been obtained by molecular biology methods, which has reduced the false positive rate.

(2) Serum circulating antigen monoclonal antibody antigen spot test is used to diagnose black fever, with a high positive rate, good sensitivity, specificity, and reproducibility. Only a small amount of serum is needed, and it can also be used for efficacy evaluation.

2. Molecular biology methods

In recent years, the use of polymerase chain reaction and DNA probe technology to detect black fever has achieved good results, with high sensitivity and specificity, but the operation is more complicated, and currently it has not been widely popularized.

Black fever treatment

General treatment

Patients should be given nutrient-rich foods, oral B vitamins and vitamin C. Take care to prevent secondary infections. For patients with severe anemia and granulocytopenia, a small amount of fresh blood will be given. If there is a bacterial infection, a corresponding antibacterial drug will be given.

2. Pathogen treatment

(1) Antimony agents are commonly used as a pentavalent antimony preparation, sodium antimonate gluconate, which has a strong insecticidal effect on Leishmania donovani, with a rapid and significant effect. If blood leukocytes, especially neutrophils, continue to decrease during treatment, the treatment is suspended. Patients with heart disease or liver disease should be used with caution. Expired drugs, especially those that have changed color, should not be used because they may become trivalent antimony to increase toxicity. If the antimony agent has not been cured for 3 courses, patients who are called "antimony agent" must be treated with non-antimony agent.

(2) Non-antimony agent This medicine has poor curative effect, long course of treatment, high recurrence rate, and large toxic and side effects. Therefore, it is only used for those who are allergic, ineffective or have granulocytosis.

3. Surgical treatment

Splenectomy is ineffective for multiple treatments, pathogens can still be found, and those with obvious splenomegaly and hypersplenism should be treated with splenectomy and treated with antimony after surgery for radical cure.

4. Complication treatment

Secondary infections should be treated with antibiotics in time. Patients with granulocytopenia are transfused with fresh blood, and leukocyte-raising drugs are appropriately applied.

Black fever prevention

1. Publicize black fever and prevention and control in endemic areas to improve residents' self-protection awareness and ability.

2. Dogs infected with Leishmania viscera by parasitology and serum immunology should be killed in time. Every May-September, the Amaranth is sprayed with organic phosphorus pesticides on houses and other places to kill Amaranth.

3. Protect susceptible people, strengthen anti-snoring measures, and avoid stings of white sturgeon.