The theme of the lesson: LEPTOSPIROSIS

The causative agents: about 200 pathogenic and about 60 saprophitic serotypes of Leptospira are known. Leptospira of 13 serogroups, 27 serotypes are distinguished in Russia. The most common serogroups are: Pomona, Hebdo-matis, Grippotyphosa, Canicola, Tarassovi.

The source of the infection: wild and domestic animals – mice and rats, dogs, pigs, cattle and others. Transmission of the infection among animals hap-pens through water and fodder. The infection is zoonotic. A man becomes in-fected during a contact of skin and mucous membranes with water, contami-nated with excrements of animals, as well as through foodstuffs, cutting meat.

Pathogenesis: Leptospira propagate during the incubation period in liver, lymph nodes and other organs, then they penetrate into blood – leptospiremia develops. Toxins of Leptospira affect walls of blood vessels and coagulatory blood system. Leptospira are hepatotropic, they fix in liver. С blood flow Lep-tospira are also spread in other internal organs – skeletal muscles, kidneys, my-ocardium, quite often – in cerebrospinal fluid. Toxico- infectious changes hap-pen in kidneys, in severe cases – they are evident, with derangement of nitrogen metabolism. Epithelium of renal tubules, cortex and subcortex of kidneys are damaged. Leptospira remain in kidneys for a long time – up to 40 days. Mes-enchymal hepatitis progresses in liver – destructive and necrotic changes in parenchyma without evident damage of hepatocytes.

Clinical presentation The incubation period – is from 4 to 14 days. The onset is acute, severe chill appears, temperature rises to 39-40оС,

headache intensifies. Typical signs are muscle pains, especially – in gastrocne-mius muscles. A lot of patients have low back pains. Fever remains during 5-9 days (sometimes – up to 11 days), it has a remittent or permanent character, quite often it is dual-frequency. Against a background of the fever muscle pains increase, hyperesthesia is possible. Face is puffy. Skin of face and neck is hyper-emic, sclerae are injected, in a number of cases exanthema is detected – morbil-liform, scarlet-fever-like or urticarial. Conjunctivitis is possible.

Most of the patients have signs of renal affection – up to acute renal fail-ure (ARF). Palpation of lumbar region can be painful (both because of muscle pains and as a result of lesions of kidneys) or painless. In urine there are signs of toxico-infectious damage of kidneys, in severe cases uremia develops and intox-ication augments against a background of ARF.

Hepatomegaly is registered. In case of a severe clinical course of lep-tospirosis hepatic function is impaired; icterus can appear (an icteric form is dis-tinguished). Thrombohemorrhagic syndrome is possible; appearance of erosions, hemorrhages in stomach and bowels is typical, in severe cases sometimes

hemoptysis, uterine bleedings appear. Severity and outcome of the disease are determined by presence of ARF and hepatorenal syndrome.

Complications: acute renal failure, serous meningitis (in 10-35% of the patients), encephalitis, myocarditis, ocular lesions – especially of iris. During an early recovery a recurrence of the disease is possible – after 5-10 days of apyrexia.

Laboratory examinations: In common blood analysis the following devi-ations are detected: anemia, moderate leukocytosis with neutrophilic left shift, a sharp increase of ESR – up to 50-60 mm/h. These derangements are caused by a toxic effect of Leptospira on bone marrow and destruction of erythrocytes. Quantity of thrombocytes and blood coagulability also decrease.

In common urine analysis in case of mild leptospirosis moderate protein-uria is detected – up to 1 g/l, in urinary sediment – there are hyaline and granular cylinders, single erythrocytes. In case of a severe clinical course of the disease these deviations are more significant: microhematuria is observed, bile pigments are detected owing to compromised liver function; diuresis is reduced.

In case of mild and especially – severe course of leptospirosis biochemical analyses are necessary:

In case of liver injury (with icteric syndrome or without it) there is an in-crease of bilirubin level, to a lesser extent – of other rates,

In case of a significant renal affection and development of ARF – there is an increase in levels of creatinine and rest nitrogen.

Laboratory diagnostics

A direct microscopy of Leptospira in a dark field is possible (method of “a crushed drop”; blood, urine are analyzed), inoculation of blood, urine and liquor (the growth is slow). More often serum diagnostics is used: reaction of aggluti-nation-lysis, microagglutination (diagnostic titer – is 1:100), CFT. Antibodies remain in blood during many years.

Treatment Antibiotic therapy is necessary in early periods. An agent of choice is

penicillin, its daily dose is 6-12 million Units, in severe cases – up to 20 million Units per day. Use of tetracyclines is possible (doxycycline by 0.1 g 2 times a day, the course – is 7 days). Preparations of reserve – are amoxiclav, ampicillin. Antibiotic therapy is carried out during 7-10 days or till the 6-8 th day of normal temperature because there is a probability of relapse (a new “wave”) of lep-tospirosis.

Leptospiral immunoglobulin (after a preliminary desensitization) is pre-scribed if the clinical course is severe: during the 1st day 10.0 ml, during the 2-3d

days of the treatment – by 5.0 ml intramuscularly.

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Pathogenetic therapy is emphasized in case of a severe clinical course of leptospirosis, especially – if there is acute renal failure and DIC-syndrome. Par-enteral introduction of isotonic solutions of glucose (5% solution – 500.0 ml) and sodium chloride (0.9% solution – 500.0 ml) with ascorbic acid, calcium preparations, aminocapronic acid is used; in case of intense muscle pains – anal-gesics. Treatment of ARF is expounded in section “HFRS”.

Hospitalization is necessary by clinical indications. Isolation of contact people is not carried out. Discharge – is performed after clinical recovery. After the discharge the

recovered people are subject to regular medical check-up during 6 months: de-pending on a lesion of a system during an acute period later on supervision of nephrologist, neurologist, ophthalmologist is required.

CONDUCTION OF THE LESSON

The aim is – to learn how to diagnose leptospirosis according to clinical data, epidemiological anamnesis, laboratory examination, as well as to plan the treatment.

Control questions at the beginning of the lesson:1. Where the disease is common?2. Name the source of the infection in case of leptospirosis3. Is a man a source of the infection in case of leptospirosis?4. Channels of leptospirosis5. What happens in kidneys, liver and vessels in case of leptospirosis?6. Name clinical signs, which are typical of leptospirosis7. Which symptoms indicate a severe clinical course of leptospirosis?8. Name complications of leptospirosis9. Name laboratory methods of confirmation of the diagnosis 10. Name groups of preparations for treatment of leptospirosis

To discuss the theme of the lesson a student manages a patient, makes a brief report about the patient’s history (in the absence of the patient with lep-tospirosis in the department). It is necessary to find out the following data about the patient:

Surname, name, patronymic name; age, place of work and residence (city, village), date of the falling ill;

Complaints at the present time.The first symptoms of the disease: temperature rise (to which level, for

how many days), intoxication, appearance of pains in muscles, in the low back

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(when, symmetrically). It is necessary to pay attention to change in color of skin, appearance of eruption.

Which derangements of health troubled the patient? Did the patient notice a decrease in urinary output?

When and how (presumably) did the infection of the patient happen? It is necessary to find out epidemiological anamnesis: sanitary living and feeding conditions, presence of rodents at home, trips to the countryside. What is the du-ration of the incubation period?

Objective data of the patient’s examination: condition, color of skin, pres-ence of dryness or edema of skin and mucous membranes, appearance of skin rash. Condition of the cardiovascular (tachycardia, arrhythmia; pulse rate, level of arterial pressure when it was measured by a doctor last time) and respiratory system, gastrointestinal tract (presence of erosions, hemorrhages, enteroparesis – during examination, palpation and according to indirect signs). A special atten-tion should be paid to condition of urinary system: diuresis, color of urine, ten-derness during palpation of the lumbar region – test of this symptom must be carried out very carefully!

Case history of the patient with leptospirosis is discussed in the group. The students together plan the examination of the patients. The teacher intro-duces the students to the results of the laboratory examinations. On the basis of all available data the students make out a diagnosis indicating severity of the disease. The treatment is discussed. The students together plan the treatment of the patient, discus it with the teacher. Making out this plan it is necessary to take into consideration severity of the disease, condition of renal and hepatic func-tions, urinary output during a day – depending on it, to determine the volume of the introduced fluid.

At the end of the lesson the students do a clinical task and answer the questions to it. Accomplishing the task the students write in their copy-books:

clinical diagnosis (taking into consideration the form and severity of the disease);

plan of the patient’s examination;they write out in Latin preparations having antibacterial and pathogenetic

actions.

Task №1 A wood-cutter had a chill suddenly, body temperature rose to 390С, there

was dizziness, intense headache, muscle pains, especially – in the lumbar region. He took aspirin, but the temperature didn’t fall. The next day the temperature was 400С, headache and myalgias intensified, vomiting and sharp weakness ap-peared, the patient consulted a doctor. Examination data: puffy and hyperemic face and neck, a full-blown injection of vessels of sclerae and conjunctiva, hem-

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orrhagic enanthema on the tunica mucosa of the mouth, isolated petechial hem-orrhages in the axillary region. The pulse is 72 beats/min. ABP – is 110/60 mm of mercury column. The edge of the liver is palpated. There is a palpatory ten-derness in the lumbar region.

Presumptive diagnosis. Plan of the examination and treatment.

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