Hello!
I would like to ask if there are any reliable data what is the best prophylactic method as it comes to Leptospira infection?
CDC recommends chemoprophylaxis with doxycycline (oral 200 mg weekly) as Dr Patel said. It has to begin 1–2 days before the period of possible exposure.
"Immunization by means of vaccines seems to provide a certain degree of protection. Vaccines are, in principle, suspensions of killed leptospires. Protection is largely serovar-specific. In areas where many serovars are causing leptospirosis, a vaccine must consist of different serovars matching those circulating locally. In some countries, where many serovars occur, vaccines consist of a mixture of a few of the most prevalent. Protective antibodies are produced only against the serovars present in the particular vaccine used.
Commercial human vaccines have been produced in France and Cuba. However, these vaccines do not induce long-term protection against infection and do not provide cross-protective immunity against heterogenous leptospiral serovars."
From WHO fact sheet
As per earlier discussion of Dr. Imran. Antileptospiral vaccines in humans: Italy, Russia and China- only to individuals employed in high risk job. Current vaccines available contain inactivated leptospires or their outer membrane fractions.They do not produce T-cell dependant response so requires annual booster.
Important thing regarding prophylaxis is Where short term exposure 200mg Doxycycline orally once a week but duration of chemoprophylaxis should not exceed 6 week. To reduce morbidity and mortality plasma level 3 mg/L or higher for 2 hrs 1 mg/L for 12-16 hrs. In subsequent wk when oral dose 200mg repeated the sufficient plasma of drug is achieved to suppress leptospiral multiplication of blood stream. The incubation period of leptospires is inversely related to infectivity dose; heavier the infecting dose, the shorter the incubation period...........
Hope so this will be useful.....
I agree with Dr.Patel that weekly Doxycycline in high risk groups as chemoprophylaxis . Leptospirosis occurs in developing tropical countries in both urban & rural areas . In urban areas , it is due to rapid urbanization & rainfall with flooding & affects lower socio-economic groups living in slums . In rural areas , it is an occupational disease , affecting those involved in agriculture . In addition , leptospirosis is grossly under diagnosed & therefore under estimated to adopt a policy of chemoprophylaaxis to vulnerable groups. It also needs a huge investment to adopt such a policy . Till then , it is better to treat undiagnosed acute febrile illness during rainfall as leptospirosis with doxycyclne ( empiric treatment of acute febrile illness vs chemoprophylaxis of asymptomatic subjects ) . This is also because the available diagnostic tests become positive after 5 days only .
Many of the policy prescriptions are still continuing as grey areas with out much scientifically documented evidence. For example blanket therapy after floods is similar one where benefit of doubt is trapped.How long the duration should be continued is another similar question.
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