What is Babesiosis?
Babesiosis (piroplasmosis, babesiosis, babesiosis) is an acute infectious disease of humans and animals characterized by intoxication, fever, the development of anemia and severe progressive course. Babesiosis refers to transmissible parasitic zoonotic infections. The human disease was first diagnosed in Yugoslavia in 1957.
Diseases occur with manifestations of fever, anemia, jaundice, hemoglobinuria. Babesioses of small and cattle, as well as dogs, have the greatest veterinary importance. Possible human disease. Distributed on all continents except Antarctica, within the ranges of vectors – several species of pasture ticks. In Russia – mainly in the north-west and south of the European part and in the steppe regions of southern Siberia.
Due to insufficient knowledge and differences of opinion of researchers, babesiosis is often identified with piroplasmosis, which is not entirely correct due to differences in the etiology of the pathogens, as well as the clinical picture of diseases. According to the International Classification of Diseases ICD-10, human babesiosis is code B60.0.
Causes of Babesiosis
The causative agent of babesiosis is of the simplest type, the class of disputes, the Babesiidae family. Three types of babesia cause human disease: Babesia divergens, rodhaini in Europe and Babesia micron in America. Babesiosis of animals is also caused by B. bovis and B. bigemina. Babesia are located inside the affected red blood cells in the center or on the periphery of the cells. When coloring on Gram have an appearance of thin rings with a diameter of 2-3 microns or formations of a pear-shaped form with a diameter of 4-5 microns.
In the world literature, to date, only about 100 cases of babesiosis have been described, most of which ended in death. Manifest forms of the disease developed in individuals with severe disorders of the immune system, in particular after splenectomy. The manifestation of babesiosis in HIV-infected people is considered likely. In people with a well-functioning immune system, the disease is asymptomatic, despite the presence of parasitemia, reaching 1-2%.
The disease is found in Europe (Scandinavian countries, France, Germany, Yugoslavia, Poland) and in the United States (east coast). The host is vole mice and other rodents, dogs, cats and cattle. Babesiosis of animals opened in 1888 by V. Babesh. Every year, tens of thousands of domestic animal cases are reported in Europe alone. The transporter is a widespread pasture mite Ixodes ricinus and argas mites. The pathogen persists in the body of ticks for life and can be transmitted transovarially. Sick tourists, agricultural workers, herders during the period of activity of ticks (spring-summer and summer-autumn seasons). It is possible to transmit the infection by blood transfusion from infected individuals who have asymptomatic parasitemia.
Pathogenesis during babesiosis
The pathogenesis of babesiosis is not well understood.
Babesiosis is transmitted through tick bites of almost all genera of the family Ixodidae, best known as transmitters of the ticks of the genera Dermacentor, Rhipicephalus, Hyalomma. Transmission occurs through saliva during the feeding of the tick.
Natural reservoir of pathogens in nature are sick babesiosis animals. Intermediate tanks – small rodents.
Sick animals for 2–3 years are immune to repeated acute infection. In many endemic areas, most or all livestock are infected.
After a tick bite, the pathogen enters the blood capillaries and red blood cells. Reproduction of babesia occurs in erythrocytes, the lysis of which is caused not only by the effects of parasites, but also by the appearance of anti-erythrocyte antibodies. Clinical manifestations occur when the number of affected red blood cells reaches 3-5%. With the destruction of red blood cells in the blood enter the waste products of parasites and heterogeneous proteins, which causes a powerful pyrogenic reaction and other toxic manifestations. Increasing anemia is accompanied by severe tissue hypoxia and impaired microcirculation. In the renal capillaries, the cell walls (“shadows”) of erythrocytes and free hemoglobin settle, which leads to the development of hematuria and acute renal failure. With massive lysis of red blood cells, disorders of the pigment metabolism develop, with accumulation of predominantly indirect bilirubin in the blood.
Symptoms of Babesiosis
The incubation period for infection with Babesia divergens through ticks is 10–15 days, through the blood – 6–12 days, and when infected with Babesia ovis sheep, 8–12 and 5–7 days, respectively. In sick animals, the body temperature rises sharply (up to 40–41 ° C), the work of the heart is disturbed, breathing becomes faster. The general condition is depressed, constipation alternates with diarrhea. Animals lose weight quickly. Milk yield of cows is reduced by 4–5 times. Milk becomes yellow, sometimes reddish, bitter in taste. On the 2-3rd day of illness, bloody urine appears. Sheep often have an abortion. The duration of the acute period of the disease is 4–8 days.
Mortality in cattle 40% or more, in sheep and goats – up to 80% of the number of patients with the acute form.
Babesiosis in a person develops mainly against the background of a lowered immune status (elderly or undergoing severe operations with AIDS). Cases of the disease began to record only in the second half of the 20th century, described several dozen cases of the disease. There is a high probability of an insufficient level of diagnostics of this disease in humans; to increase it, considerable work is being done in many countries. A person with a normal immune system is asymptomatic, despite a high degree of parasitemia (1-2%).
Complications. Babesiosis is naturally complicated by acute renal failure, acute renal-hepatic and multiple organ failure. Joining non-specific pneumonia worsens the prognosis.
Diagnosis of Babesiosis
Clinical diagnosis is difficult. Prolonged fever in combination with anemia, hepatomegaly in the absence of the effect of treatment with the use of antibacterial agents is the basis for laboratory studies on ba-beioz. It is especially important to take into account epidemiological data (tick bites, stay in an endemic area) and to identify violations of the immune status of the patient. The diagnosis is confirmed by parasitological detection of the pathogen in a smear and a thick drop of blood, as well as in the reaction of indirect immunofluorescence. Diagnostic titer with a single examination of at least 1: 256. Complement fixation is also used.
With a low parasitemia, sometimes a biological method is used, in which the patient’s blood is injected with splenectomy golden hamsters. After 2-4 weeks, animals develop a disease and babesies are easily detected in a blood smear.
Differential diagnosis is carried out with tropical malaria, sepsis, blood diseases, HIV infection, HFRS.
Piroplasmil, berenil, hemosporidin, akaprin, ihtarkan, albargin, tiargen, naganin, and others give a good therapeutic effect. Sick animals are given complete rest (they cannot be overtaken), they are provided with green and juicy fodder.
For severe forms of babesiosis in humans, combinations of clindamycin and quinine or azithromycin and atovaquone are recommended. In severe cases, blood transfusion is necessary.
Forecast. Without etiotropic treatment, the disease is often (50-80% of cases) is fatal. With the timely start of antiparasitic therapy, the prognosis is favorable.
Specific prevention is not developed. Destruction of ticks and rodents on pastures, treatment of animals with acaricides. For humans – the use of anti-tick drugs.