Leptospirosis

Editor's Notes

• #3: Gram negative organism Leptospira interrogans main types affecting humans are L. Interrogans icterohaemorrhagie, Canicola, hardjo and pommona Need High index of clinical suspicion
• #6: The conditions that are favourable for maintenance and transmission of Leptospirosis are: a) Reservoir and carrier hosts Leptospirosis has a very wide range of natural rodent, and non-rodent reservoir hosts especially rats, cattle, dogs, foxes, rabbits, etc. The animals act as carriers of the leptospires and excrete large number of leptospires in their urine, thus responsible for the contamination of large and small water bodies as well as soil. b) Flooding, drainage congestion Flooding and drainage congestion may be risk factors for contamination of water bodies with infected animal urine. Water logged areas may force rodent population to abandon their burrows and contaminatethe stagnant water by their urine. c) Animal-Human Interface The potential for infection increases through exposure from occupational or recreational activities without proper protection. Poor cleanliness/sanitation in recreational areas may attract animal host such as rodent thus increases the risk of contamination. These may be due to poor maintenance of facilities, improper disposal of waste and public attitude/ apathy. d) Human host risk factors Several sections of the population are more susceptible to infection such as those not previously exposed to the bacteria in their environment (naïve immunities), and those with chronic disease and open skin wounds.
• #13: Notes on Laboratory Diagnosis • In cases which needed to be confirmed (hospitalized and suspected death cases), serum samples should be sent for confirmation by MAT. The MAT is considered the "gold standard" or cornerstone of serodiagnosis because of its unsurpassed diagnostic (serovar/serogroup) specificity in comparison with other currently available tests. Second serum samples must be taken to detect fourfold or greater rise in titre. • Simple serological screening method can be done using the rapid test kit for Leptospira. Reminder: any leptospirosis rapid test kit to be used must be validated/approved by IMR. • The ELISA/other rapid tests detect IgM antibodies. The presence of IgM antibodies may indicate current or recent leptospirosis. A patient’s serum may be positive 5 to 10 days after onset of symptoms but not usually before this. Reminder: IgM-class antibodies may remain detectable for several years. • If the initial sample was taken at an early stage in the infection, the ELISA test may be positive but MAT negative. Therefore a follow-up sample is required. Test may be negative if the serogroup of the infecting strain does not react with the Patoc 1 serovar strain used as the antigen. If antibiotics are given from the beginning of the illness, the immune and antibody response may be delayed. • The diagnosis is also confirmed by isolation of Leptospires from blood (first 7 days) or CSF (days 4-10) during the acute illness, from urine (days ≥7) and from tissue samples, by using special media. Inoculation of young guinea pigs, hamsters or gerbils can also be carried out for isolation of leptospires. Leptospires die quickly in urine. Clean urine sample should be inoculated into appropriate culture medium not more than 2 hours after voiding. Survival in acid urine may be increased by making it neutral. For postmortem diagnosis, in addition to serology and culture, leptospires can be demonstrated in tissues using PCR or immunohistochemical staining, notably by direct immunofluorescence.
• #14: Figure 1: Leptospiremic phases in conjunction with the laboratory methods of diagnosis (4). Note: Biphasic nature of leptospirosis and relevantinvestigations at different stages of disease. Specimens 1 and 2 for serology are acute-phase specimens, 3 is a convalescent-phase sample which may facilitate detection of a delayed immune response, and 4 and 5 are follow-up samples which can provide epidemiological information, such as the presumptive infecting serogroup (4).
• #15: Total WBC maybe normal or high as 50 000 per microliter Thrombocytopenia is common Urine may contain bile, protein, casts and red cells Elevated bilirubin and liver enzymes seen in 75 percent cases Elevated creatinine in 50% CSF may show polymorphonuclear of lymphocytic pleocytosis with minimal or moderately elevated protein concentrations and normal glucose CK elevated in 50% of cases
• #17: The Jarisch-Herxheimer reaction is a reaction to endotoxins released by the death of harmful organisms within the body Presentation It resembles bacterial sepsis and can occur after initiation of antibacterials, such as penicillin or tetracycline, for the treatment of louse-borne relapsing fever (80-90% of patients) and in tick-borne relapsing fever (30-40%). An association has been found between the release of heat-stable proteins from spirochetes and the reaction. Typically, the death of these bacteria and the associated release of endotoxins or lipoproteins occurs faster than the body can remove the substances. It usually manifests within a few hours of the first dose of antibiotic as fever, chills, rigor, hypotension, headache, tachycardia, hyperventilation, vasodilation with flushing, myalgia (muscle pain), exacerbation of skin lesions and anxiety. The intensity of the reaction indicates the severity of inflammation. Reaction commonly occurs within two hours of drug administration, but is usually self-limiting. Treatments Prophylaxis and treatment with an anti-inflammatory agent may stop progression of the reaction. Oral aspirin every four hours for 1–2 days, or 60 mg of prednisone orally or intravenously has been used as an adjunctive treatment[citation needed]. However, steroids are generally of no benefit. Patients must be closely monitored for the potential complications (collapse and shock) and may require i.v. fluids to maintain adequate blood pressure. If available, meptazinol, an opioid antagonist, should be administered to reduce the severity of the reaction. Anti TNF-a may also be effective.[citation needed]
• #19: The cost effectiveness and risk versus benefits of antibiotic prophylaxis for leptospirosis remains unclear. If prophylaxis is considered, the possible options include: Pre-exposure Prophylaxis • May be considered for people at high risk of exposure to potentially contaminated sources e.g. soldiers going into jungles, rescue team, persons involved in activities in possible high risk areas e.g. adventurous sports. • Dose: Doxycycline 200mg stat dose then weekly throughout the stay OR Azithromycin 500mg stat dose then weekly throughout the stay (For pregnant women and those who are allergic to Doxycycline) • However the benefit of pre-exposure prophylaxis remains controversial where possible benefits need to be balanced with potential side effects (e.g. doxycycline induced photosensitivity, nausea, etc.) Empirical treatment for Post-Exposure • In an outbreak, there may be a role for post exposure prophylaxis for those exposed to a common source as the index case. Dose: • Doxycycline 200mg stat dose then followed by 100mg BD for 5 – 7 days for those symptomatic with the first onset of fever. OR • Azithromycin 1gm on Day-1, followed by Azithromycin 500mg daily for 2 days (For pregnant women and those who are allergic to Doxycycline) Note: The role of prophylaxis in children has not been adequately studied