Diagnostics

ON INFECTION, the microorganism can be found in blood for the first 7 to 10 days (invoking serologically identifiable reactions) and then moving to the kidneys. After 7 to 10 days, the microorganism can be found in fresh urine. Hence, early diagnostic efforts include testing a serum or blood sample serologically with a panel of different strains. It is also possible to culture the microorganism from blood, serum, fresh urine and possibly fresh kidney biopsy.

Kidney function tests (Blood Urea Nitrogen and creatinine) as well as blood tests for liver functions are performed. The latter reveal a moderate elevation of transaminases. Brief elevations of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and gamma-glutamyltransferase (GGT) levels are relatively mild.

These levels may be normal, even in children with jaundice. Diagnosis of leptospirosis is confirmed with tests such as Enzyme-Linked Immunosorbent Assay (ELISA) and PCR. Serological testing, the MAT (microscopic agglutination test), is considered the gold standard in diagnosing leptospirosis. As a large panel of different leptospira need to be subcultured frequently, which is both laborious and expensive, it is underused, mainly in developing countries.

Differential diagnosis list for leptospirosis is very large due to diverse symptomatics. For forms with middle to high severity, the list includes dengue fever and other hemorrhagic fevers, hepatitis of various etiologies, viral meningitis, malaria and typhoid fever. Light forms should be distinguished from influenza and other related viral diseases. Specific tests are a must for proper diagnosis of leptospirosis.

Under circumstances of limited access (eg, developing countries) to specific diagnostic means, close attention must be paid to anamnesis of the patient. Factors like certain dwelling areas, seasonality, contact with stagnant contaminated water (Bathing swimming, working on flooded meadows, etc) and/or rodents in the medical history support the leptospirosis hypothesis and serve as indications for specific tests. 

Leptospira can be cultured in Ellinghausen-McCullough-Johnson-Harris medium, which is incubated at 28 to 30°C. The median time to positivity is three weeks with a maximum of 3 months. This makes culture techniques useless for diagnostic purposes but is commonly used in research.

Treatment

Leptospirosis treatment is a relatively complicated process comprising two main components: suppressing the causative agent and fighting possible complications. Aetiotropic drugs are antibiotics, such as cefotaxime, doxycycline, penicillin, ampicillin, and amoxicillin (doxycycline can also be used as a prophylaxis).

There are no human vaccines; animal vaccines are only for a few strains and are only effective for a few months. Human therapeutic dosage of drugs is as follows: doxycycline 100mg orally every 12 hours for 1 week or penicillin 1–1.5 MU every 4 hours for 1 week. Doxycycline 200–250mg once a week is administered as a prophylaxis. In dogs, penicillin is most commonly used to end the leptospiremic phase (infection of the blood), and doxycycline is used to eliminate the carrier state. Supportive therapy measures (esp in severe cases) include detoxication and normalisation of the hydro-electrolytic balance.

Glucose and salt solution infusions may be administered; dialysis is used in serious cases. Elevations of serum potassium are common and if the potassium level gets too high special measures must be taken. Serum phosphorus levels may likewise increase to unacceptable levels due to renal failure. Treatment for hyperphosphatemia consists of treating the underlying disease, dialysis where appropriate or oral administration of calcium carbonate, but not without first checking the serum calcium levels (these two levels are related).

Corticosteroids administration in gradually reduced doses (eg, prednisolone starting from 30–60 mg) during 7–10 days is recommended by some specialists in cases of severe haemorrhagic effects. Organ specific care and treatment are essential in cases of renal, liver or heart involvement.