How is anthrax diagnosed?

Diagnosis of anthrax dermal form is based on the characteristic local changes: the presence of a black scab with a corolla of hyperemia ("black coal on a red background"), a gelatinous painless edema and regional lymphadenitis, the appearance of common symptoms after the formation of carbuncle. Of particular importance for diagnosis are epidemiological data (occupation, livestock care, slaughtering, cutting carcasses, working with skins, skins, etc., wearing leather and non-manufactured articles, eating meat that has not undergone veterinary and sanitary control, especially with forced slaughter of sick animals). With the generalized form of the disease, it is difficult to establish a diagnosis without epidemiological and laboratory data.

Etiological laboratory diagnosis of anthrax is:

• bacteriological studies, which take place in three stages: microscopy of smears from pathological material, isolation of pure culture of the pathogen on nutrient media and study of its properties, biological test on laboratory animals:
• detection of the genetic material of the pathogen by the PCR method;
• serological tests:
• immunohistochemical studies;
• skin and allergic test with anthraxin.

If suspected skin form of anthrax for bacteriological examination, take the contents of vesicles or carbuncles, separated ulcers, severed scab and blood.

If a generalized form is assumed, blood from the ulnar vein, urine, vomit, bowel movements, cerebrospinal fluid (in the presence of meningitis symptoms), sputum are taken for laboratory examination. In bacteriological studies, the pathogen is detected by bacterioscopy and fluorescence microscopy. In the material, the bacteria are arranged in pairs or in the form of chains surrounded by a common capsule. Spores, as a rule, are located in the center. These same substrates are used for sowing on nutrient media in order to isolate the pure culture of the pathogen, as well as for setting bioassays on laboratory animals.

Serological diagnosis of anthrax is based on the use of the fluorescent antibody method, RIGA (RPGA), ELISA.

If a skin anthrax is suspected, a puncture biopsy of the skin at the center of the primary affect can be performed, followed by immunohistochemical examination of the material obtained or by staining with silver. The test systems for the determination of the genetic material of an anthrax pathogen by the PCR method have been developed. Apply a skin-allergic test with anthraxin, which from the 3rd day of the disease becomes positive in 82% of cases. When investigating livestock raw materials (skins, wool), the Aspoli thermoprecipitation reaction and other methods are used.

In the generalized version, an X-ray examination of the lungs is necessary. If there is a suspicion of an intestinal variant, ultrasound of the abdominal cavity organs is indicated, with clinical signs of meningitis - LP. In the blood, moderately pronounced inflammatory changes, thrombocytopenia, in the study of urine - signs of toxic nephrosis.

[1], [2], [3],

Example of the formulation of the diagnosis

A22.0. Anthrax, skin form, severe course of the disease (from culture of B. Anthracis isolated from the carbuncle being separated).

Patients with an established diagnosis or suspected anthrax are subject to emergency hospitalization in compliance with all rules of transportation and sanitary-epidemiological regime and isolation in boxes or separate wards.

[4], [5], [6], [7], [8], [9], [10]

Differential diagnosis of anthrax

With cutaneous form, differential diagnosis of anthrax is carried out with a furuncle, carbuncle, phlegmon, erysipelas, an insect bite, sometimes with a cutaneous form of tularemia and plague. For furuncle and carbuncle is characterized by sharp soreness, the presence of pus under the crust, the absence of a common edema. At a mug, fever and intoxication precede local changes, characterized by severe erythema on the skin, moderate soreness, a clear boundary between the lesion site and healthy skin. With increased sensitivity to the poisons of some insects (wasp, hornet, bee, ant, etc.), there may appear at the site of a bite of hyperemia, a sharp dense edema with the presence of soreness and after a bite in the form of a point in the center. In this case, fever and intoxication are possible. All these symptoms develop within a few hours after a painful bite.

With dermal form of tularemia, the primary affect (sore) is not very painful. There is no infiltration and edema of soft tissues, they detect a regional bubo. When plague, skin lesions are sharply painful, there are hemorrhages on the skin, marked intoxication.

Differential diagnosis of anthrax of the generalized form is carried out with sepsis, meningococcus, pulmonary plague, croupous pneumonia, purulent meningitis, acute intestinal infections, peritonitis, intestinal obstruction. Without appropriate epidemiological and laboratory data, differential diagnosis presents great difficulties, often diagnosed after death.

[11], [12], [13], [14], [15], [16]