Clinical picture by periods
The course of leptospirosis is divided into the initial period and the period of peak manifestations. The disease always starts acutely and is accompanied by a pronounced general infection syndrome.
Initial period:
- Intoxication and appearance: high fever, hyperemia and puffiness of the face, injection of scleral and conjunctival vessels, frequent appearance of herpes.
- Organs and systems: hepatosplenomegaly (primarily due to the liver). Sharp tenderness in the calf muscles.
- Hemorrhagic syndrome: petechiae, hemorrhages in the sclera, epistaxis, hematuria.
- Additionally: polymorphic exanthema on days 3–6, signs of meningism, sometimes the appearance of initial jaundice.
Period of peak manifestations:
- Increase in intoxication: insomnia, agitation, tachycardia with decreased blood pressure, dryness of mucous membranes.
- Kidney damage: positive costovertebral angle tenderness sign, oliguria (up to anuria), dark urine.
- Icteric form: increase in icterus of the skin and sclera, hepatomegaly, stool acholia.
- Complications: serous (or purulent) meningitis, intensification of hemorrhagic manifestations (DIC syndrome).
Laboratory diagnostics
Baseline blood tests reflect a pronounced inflammatory process and renal parenchyma damage.
- Complete blood count: leukocytosis, neutrophilia with a left shift of the formula, significant increase in ESR.
- Urinalysis: proteinuria, leukocyturia, cylindruria, and microhematuria.
Specific diagnostics:
- Microscopy: detection of motile leptospires in a crushed drop of blood (in the first days), urine, or CSF using dark-field microscopy.
- Serology: indirect hemagglutination assay (IHA), microscopic agglutination test (MAT), agglutination lysis reaction (ALR), complement fixation test (CFT), detection of IgM class antibodies by ELISA.
- Molecular genetic method: PCR of blood, urine, or CSF to detect pathogen DNA.
- Bacteriological method: culture of blood, CSF, and urine (a lengthy process).
- Biological assay: infection of guinea pigs.
Diagnosis formulation and management tactics
Differential diagnosis is primarily performed with HFRS (hemorrhagic fever with renal syndrome), viral hepatitis, typhoid fever, and meningitis of other etiologies.
The detailed clinical diagnosis must indicate the form (icteric/anicteric), severity (mild, moderate, severe), and leading syndromes (hepatorenal, hemorrhagic, renal, meningeal). Complications (AKI, infectious-toxic shock) must be indicated.
The treatment plan includes:
- Etiotropic therapy: antibiotics (drug of choice — benzylpenicillin intramuscularly in a daily dose of up to 24 million IU) and administration of heterologous antileptospirovic immunoglobulin.
- Pathogenetic therapy: intravenous infusion of colloidal and crystalloid solutions for detoxification and correction of water-electrolyte balance.
- Symptomatic treatment: analgesics, vitamins, sedatives.
Discharge of patients (convalescents) is carried out only after complete clinical recovery followed by follow-up observation (dispensary monitoring).
Briefly: answers to topical questions
What are the main routes of transmission and mechanisms of infection in leptospirosis?
Infection with leptospirosis occurs predominantly via the fecal-oral transmission mechanism. The main routes of human infection include:
- Waterborne — is the main route of pathogen transmission.
- Foodborne (or alimentary) — occurs when consuming contaminated food.
- Contact — infection occurs through microlesions of the skin and intact mucous membranes.
On what day of the disease is the microscopic agglutination test (MAT) performed to confirm leptospirosis?
The microscopic agglutination test (MAT) with leptospires to confirm the diagnosis is performed starting from the 6th–12th day from the onset of the disease. This method aims to determine specific antibodies against the pathogenic agent Leptospira interrogans. The minimum diagnostic titer is considered to be 1:100, provided that an increase in the antibody titer is observed dynamically.
What changes in the biochemical blood test are characteristic of leptospirosis?
Changes in the biochemical blood test depend on the clinical form of the disease and the development of complications:
- In the icteric form — there is a decrease in total protein and albumin levels, hyperbilirubinemia (primarily due to conjugated bilirubin), an increase in ALT, AST, alkaline phosphatase, and amylase.
- With the development of AKI — an increase in urea and creatinine levels and hyperkalemia are characteristic.
- With pancreatitis — an elevated amylase level is detected.
To remember the main manifestations of severe leptospirosis, use the "Four P's" rule: Kidneys (oliguria, blood in the urine), Liver (jaundice, hepatomegaly), Integument (hemorrhages, facial hyperemia, rash), and Pain (severe muscle pain, especially in the calves).
Class and exam questions
What is the difference between the icteric and anicteric forms of leptospirosis?
The icteric form is accompanied by pronounced icterus of the skin and sclera, hyperbilirubinemia (due to the direct fraction), stool acholia, and usually has a more severe course. In the anicteric form, renal and hemorrhagic syndromes may remain leading.
What diseases are included in the differential diagnosis?
The primary differential search is conducted with hemorrhagic fever with renal syndrome (HFRS), viral hepatitis, typhoid fever, and meningitis of other etiologies.
Which antibiotic is the drug of choice for leptospirosis?
According to the protocol, the drug of choice is benzylpenicillin, which is prescribed intramuscularly in high dosages (up to 24 million IU per day).
What epidemiological history data point to leptospirosis?
Indications of contact with fresh or stagnant water (swimming, fishing, washing hands in a pit), working with pigs, rodent bites (rats), or contact with their secretions.
What else to study on this topic
- Severity criteria and algorithm for managing acute kidney injury (AKI).
- Differential diagnosis of leptospirosis and HFRS based on clinical and laboratory markers.
- Course features and CSF findings in leptospiral meningitis.
- Interpretation of MAT results and serial serological studies.
- Specifics of taking an epidemiological history in endemic regions.
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