Overview
Babesiosis is a zoonotic parasitic disease caused by the parasitic blood protozoa of the genus Babesia, which is infected by tick vectors. The acute onset of human babesiosis is similar to malaria and is characterized by intermittent fever, splenomegaly, jaundice and hemolysis.
Causes
Babesia protozoa are tick-borne protozoa that parasitize the erythrocytes of vertebrates such as mammals and birds. The most common pathogen of babesiosis is the vole babesia, which is the main natural host for the parasite. Deer ticks in the hard tick family are common vectors, and young ticks infected while sucking the blood of infected deer can transmit Babesia to humans. Adult ticks can also sometimes transmit Babesia to humans. Babesia enters red blood cells, matures, and then reproduces asexually by budding. The infected erythrocyte ruptures, releasing the protozoa, which can then enter other erythrocytes. Babesiosis can also be transmitted by blood transfusion.
Symptoms
The incubation period is 1 to 9 weeks. Clinical typeThe symptoms at the beginning of the disease vary in severity. Depending on the severity of the disease, there are light, medium, and heavy forms. In chronic cases, protozoaemia may last for months or even years.
1. Mild
There may only be low or normal body temperature, slight fatigue and malaise, mild headache, weakness and loss of appetite.
2. Medium
The onset of the disease is rapid, with a high fever of 39°C to 40°C, chills and trembling, and profuse sweating. Severe headache, myalgia, and even pain in the joints of the body. Sometimes photophobia, depression or agitation, trance. Nausea and vomiting may occur, but there is no meningeal irritation. There is mild to moderate enlargement of the spleen and no abnormalities in the lymph nodes. There is no rash.
3. Severe disease
Clinical manifestations at onset are the same as in the medium-sized form. In critically ill patients, hemolytic anemia develops rapidly, accompanied by jaundice, proteinuria, hematuria and renal dysfunction. Patients with a history of splenectomy often have more severe clinical manifestations. The severe type mostly dies within 5 to 8 days after the onset of the disease.
Examination
1. Laboratory examination
High reticulocyte count, low white blood cell count with left shift of nucleus, thrombocytopenia, abnormal liver function test, rapid sedimentation, positive proteinuria and hematuria.
2. Microscopic examination of blood smear
Multiple cyclic bodies are found in red blood cells without pigment granules. In the terminal blood smear of patients with hemolytic anemia, a very small number of red blood cells may contain protozoa.
3. Inoculation test
Inoculate 1.0ml of patient’s blood into the abdominal cavity of golden gopher, it can produce protozoa parasitemia in 12-14 days, and the pathogenic worms can be seen in the tail blood collected after 1 month.
4.Serologic diagnosis
Indirect fluorescent antibody test, indirect hemagglutination, capillary agglutination test or enzyme-linked immunosorbent assay (ELISA) can be used, and polymerase chain reaction (PCR) can be used to rapidly determine deoxyribonucleic acid (DNA) within a few hours.
Diagnosis
1. There may be a history of tick bite; many patients cannot recall a history of tick bite.
2. There may be typical clinical signs: chills, fever, sweating, headache, muscle and joint pain, anemia, and splenomegaly.
3. The diagnosis is confirmed by the presence of Babesia in the blood smear. The finding of 4-part or basket-like worms or a large number of extra-erythrocytic protozoa is a valuable diagnostic clue. Serologic tests or detection of Babesia DNA in the blood by PCR are also useful. Inoculation of the patient’s blood into hamsters or gerbils, followed by observation of protozoaemia in the inoculated rats can also be used as a diagnostic tool.
Treatment
1. Symptomatic therapy
Those with high fever and severe pain should be treated with antipyretic and analgesic treatment. If there is obvious hemolysis, blood transfusion can be given. Pay attention to rest and diet.
2.Drug treatment
Clindamycin is the first choice of drug, intramuscular injection. For preterm infants infected with Babesia microti by blood transfusion, quinine can be added and taken orally. For adult patients who have had their spleens removed, clindamycin can be used and injected intramuscularly. Also administer quinine orally.
Clindamycin alone, intramuscular injection or with quinine oral use, can rapidly reduce fever, but also reduce the protozoaemia, which is used in recent years for the treatment of Babesia microti caused by human babesiosis of safe and effective drugs. Quinine sulfate and chloroquine are also effective.