Use of doxycycline for leptospirosis after high-risk exposure in São Paulo, Brazil

Current treatment options for leptospirosis: a mini-review

Leptospirosis, one of the most common global zoonotic infections, significantly impacts global human health, infecting more than a million people and causing approximately 60,000 deaths annually. This mini-review explores effective treatment strategies for leptospirosis, considering its epidemiology, clinical manifestations, and current therapeutic approaches. Emphasis is placed on antibiotic therapy, including recommendations for mild and severe cases, as well as the role of probiotics in modulating the gut microbiota. Furthermore, novel treatment options, such as bacteriophages and newly synthesized/natural compounds, are discussed, and the findings are expected to provide insights into promising approaches for combating leptospirosis.

Antibiotic prophylaxis for leptospirosis

BACKGROUND

Leptospirosis is a global zoonotic and waterborne disease caused by pathogenic Leptospira species. Antibiotics are used as a strategy for prevention of leptospirosis, in particular in travellers and high-risk groups. However, the clinical benefits are unknown, especially when considering possible treatment-associated adverse effects. This review assesses the use of antibiotic prophylaxis in leptospirosis and is an update of a previously published review in the Cochrane Library (2009, Issue 3).

OBJECTIVES

To evaluate the benefits and harms of antibiotic prophylaxis for human leptospirosis.

SEARCH METHODS

We identified randomised clinical trials through electronic searches of the Cochrane Hepato-Biliary Group Controlled Trials Register, CENTRAL, MEDLINE, Embase, LILACS, Science Citation Index Expanded, and other resources. We searched online clinical trial registries to identify unpublished or ongoing trials. We checked reference lists of the retrieved studies for further trials. The last date of search was 17 April 2023.

SELECTION CRITERIA

We included ⁠⁠randomised clinical trials of any trial design, assessing antibiotics for prevention of leptospirosis, and with no restrictions on age, sex, occupation, or comorbidity of trial participants. We looked for trials assessing antibiotics irrespective of route of administration, dosage, and schedule versus placebo or no intervention. We also included trials assessing antibiotics versus other antibiotics using these criteria, or the same antibiotic but with another dose or schedule.

DATA COLLECTION AND ANALYSIS

We followed Cochrane methodology. The primary outcomes were all-cause mortality, laboratory-confirmed leptospirosis regardless of the presence of an identified clinical syndrome (inclusive of asymptomatic cases), clinical diagnosis of leptospirosis regardless of the presence of laboratory confirmation, clinical diagnosis of leptospirosis confirmed by laboratory diagnosis (exclusive of asymptomatic cases), and serious adverse events. The secondary outcomes were quality of life and the proportion of people with non-serious adverse events. We assessed the risk of bias of the included trials using the RoB 2 tool and the certainty of evidence using GRADE. We presented dichotomous outcomes as risk ratios (RR) and continuous outcomes as mean difference (MD), with their 95% confidence intervals (CI). We used a random-effects model for our main analyses and the fixed-effect model for sensitivity analyses. Our primary outcome analyses included trial data at the longest follow-up.

MAIN RESULTS

We identified five randomised clinical trials comprising 2593 participants that compared antibiotics (doxycycline, azithromycin, or penicillin) with placebo, or one antibiotic compared with another. Four trials assessed doxycycline with different durations, one trial assessed azithromycin, and one trial assessed penicillin. One trial had three intervention groups: doxycycline, azithromycin, and placebo. Three trials assessed pre-exposure prophylaxis, one trial assessed postexposure prophylaxis, and one did not report this clearly. Four trials recruited residents in endemic areas, and one trial recruited soldiers who experienced limited time exposure. The participants' ages in the included trials were 10 to 80 years. Follow-up ranged from one to three months. Antibiotics versus placebo Doxycycline compared with placebo may result in little to no difference in all-cause mortality (RR 0.15, 95% CI 0.01 to 2.83; 1 trial, 782 participants; low-certainty evidence). Prophylactic antibiotics may have little to no effect on laboratory-confirmed leptospirosis, but the evidence is very uncertain (RR 0.56, 95% CI 0.25 to 1.26; 5 trials, 2593 participants; very low-certainty evidence). Antibiotics may result in little to no difference in the clinical diagnosis of leptospirosis regardless of laboratory confirmation (RR 0.76, 95% CI 0.53 to 1.08; 4 trials, 1653 participants; low-certainty evidence) and the clinical diagnosis of leptospirosis with laboratory confirmation (RR 0.57, 95% CI 0.26 to 1.26; 4 trials, 1653 participants; low-certainty evidence). Antibiotics compared with placebo may increase non-serious adverse events, but the evidence is very uncertain (RR 10.13, 95% CI 2.40 to 42.71; 3 trials, 1909 participants; very low-certainty evidence). One antibiotic versus another antibiotic One trial assessed doxycycline versus azithromycin but did not report mortality. Compared to azithromycin, doxycycline may have little to no effect on laboratory-confirmed leptospirosis regardless of the presence of an identified clinical syndrome (RR 1.49, 95% CI 0.51 to 4.32; 1 trial, 137 participants), on the clinical diagnosis of leptospirosis regardless of the presence of laboratory confirmation (RR 4.18, 95% CI 0.94 to 18.66; 1 trial, 137 participants), on the clinical diagnosis of leptospirosis confirmed by laboratory diagnosis (RR 4.18, 95% CI 0.94 to 18.66; 1 trial, 137 participants), and on non-serious adverse events (RR 1.12, 95% CI 0.36 to 3.48; 1 trial, 137 participants), but the evidence is very uncertain. The certainty of evidence for all the outcomes was very low. None of the five included trials reported serious adverse events or assessed quality of life. One study is awaiting classification. Funding Four of the five trials included statements disclosing their funding/supporting sources, and the remaining trial did not include this. Three of the four trials that disclosed their supporting sources received the supply of trial drugs directly from the same pharmaceutical company, and the remaining trial received financial support from a governmental source.

AUTHORS' CONCLUSIONS

We do not know if antibiotics versus placebo or another antibiotic has little or have no effect on all-cause mortality or leptospirosis infection because the certainty of evidence is low or very low. We do not know if antibiotics versus placebo may increase the overall risk of non-serious adverse events because of very low-certainty evidence. We lack definitive rigorous data from randomised trials to support the use of antibiotics for the prophylaxis of leptospirosis infection. We lack trials reporting data on clinically relevant outcomes.

Current Evidence on the Antimicrobial Treatment and Chemoprophylaxis of Human Leptospirosis: A Meta-Analysis

BACKGROUND

Leptospirosis is a worldwide zoonotic infection, and its management needs to be refined. This study aims to discern which antibiotic would be the best option to treat leptospirosis disease and analyze the efficacy of chemoprophylaxis regimens to prevent this illness.

METHODS

systematic review and meta-analysis on the efficacy of antibiotic treatment and chemoprophylaxis of leptospirosis in humans.

RESULTS

Ten clinical trials compared an antibiotic treatment with placebo or other antibiotic treatments in leptospirosis (the most recent one was published in 2007). The meta-analysis shows no effect of penicillin treatment on mortality compared to placebo (OR 1.65; 95% CI 0.76-3.57; p = 0.21). There are no differences between penicillin and cephalosporins or doxycycline. Penicillin does not reduce the time of defervescence (MD-0.16; 95% CI (-1.4) -1.08; p = 0.80) nor hospital stay (MD 0.15; 95% CI (-0.75)-1.06; p = 0.74). Besides, the data did not demonstrate any effectiveness of the use of penicillin in terms of the incidence of oliguria/anuria, the need for dialysis treatment, time to creatinine normalization, incidence of jaundice, or the liver function normalization time. Eight trials have assessed prophylactic treatment against leptospirosis with different strategies. A weekly dose of 200 mg of doxycycline does not show benefit versus placebo regarding the number of new cases of symptomatic leptospirosis (OR 0.20; 95% CI 0.02-1.87; p = 0.16). A single dose of doxycycline at exposure to flood water could have a beneficial effect (OR 0.23; 95% CI 0.07-0.77; p = 0.02). None of the other chemoprophylaxis regimens tested have shown a statistically significant effect on the number of new symptomatic cases.

CONCLUSION

There is no evidence that antibiotics are a better treatment than placebo regarding mortality, shortening of fever, liver and kidney function, or reduction in the hospital stay. On the other hand, neither doxycycline nor penicillin, nor azithromycin have shown statistically significant differences in preventing symptomatic infection. Well-designed clinical trials, including other antibiotics such as quinolones or aminoglycosides, are urgently needed to improve our understanding of the treatment for this infection, which continues to be a neglected disease.

Household rat infestation in urban slum populations: Development and validation of a predictive score for leptospirosis

Domestic rats are the principal reservoir for urban leptospirosis. However, few studies have identified infestation markers in slums and evaluated their predictivity for leptospirosis risk. We compared households with leptospirosis cases in Salvador, Brazil between 2007 and 2009 and their neighbors using a case control design, surveying for rodent infestation signs and environmental characteristics. With the 2007-2008 data, a conditional logistic regression modeling identified the peridomiciliar presence of rodent burrows (OR, 3.30; 95% CI, 1.50-7.26), rat feces (2.86; 1.24-6.59), runs (2.57; 1.06-6.22), households bordering abandoned houses (2.48; 1.04-6.02), and unplastered walls (2.22; 1.02-6.02) as risk factors and developed a predictive score for leptospirosis. With an independent data set from 2009, a receiver operating characteristic (ROC) curve analysis evaluated the prediction score performance, with the area under the curve being 0.70 (95% CI, 0.64-0.76) for score development and 0.71 (0.65-0.79) for validation. Results indicate that high proportions of urban slum households are infested with R. norvegicus. The score performed well when identifying high-risk households within slums. These findings need confirmation in other urban centers, but suggest that community-based screening for rodent infestation can allow to target rodent and environmental control measures in populations at highest risk for leptospirosis.

The Use of Chemoprophylaxis after Floods to Reduce the Occurrence and Impact of Leptospirosis Outbreaks

Record-breaking and devastating rainfall events have occurred in the past decade. Rain and floods are considered the main risk factors for leptospirosis and several outbreaks have been reported following extreme weather events. In such situations, one possible intervention to prevent leptospirosis cases in high-risk groups is the use of chemoprophylaxis. However, not enough evidence of its effect is available. The objectives of this study were to review the literature on the current practices of chemoprophylaxis for leptospirosis and to explore, using a mathematical model, how various chemoprophylaxis scenarios may affect the progression of a leptospirosis outbreak. Twenty-six peer-reviewed publications were selected (10 quantitative studies, two systematic reviews and 14 articles of other types). Oral doxycycline was the most used antibiotic for chemoprophylaxis of leptospirosis. Post-exposure prophylaxis was assessed in four studies following a natural disaster. Although evidence of the effectiveness of post-exposure prophylaxis is inconsistent, the direction of association supported a protective effect for morbidity and mortality. The theoretical model showed how the assumed benefit of chemoprophylaxis was influenced by the time and rate of administration. Future models should consider the heterogeneity of affected communities, improved estimates of the effect of chemoprophylaxis on leptospirosis infection and disease, as well as potential detrimental impacts. Additional research is critical to provide clear evidence-based recommendations for leptospirosis control during an outbreak. The results of this study suggest that chemoprophylaxis may provide some protection in reducing the number of leptospirosis cases after a high-risk exposure; however, the effective benefit may depend on a variety of factors such as the timing and coverage of prophylaxis. The information summarized can be used to support decision-making during a high-risk event.

Leptospirosis in humans

Leptospirosis is a widespread and potentially fatal zoonosis that is endemic in many tropical regions and causes large epidemics after heavy rainfall and flooding. Infection results from direct or indirect exposure to infected reservoir host animals that carry the pathogen in their renal tubules and shed pathogenic leptospires in their urine. Although many wild and domestic animals can serve as reservoir hosts, the brown rat (Rattus norvegicus) is the most important source of human infections. Individuals living in urban slum environments characterized by inadequate sanitation and poor housing are at high risk of rat exposure and leptospirosis. The global burden of leptospirosis is expected to rise with demographic shifts that favor increases in the number of urban poor in tropical regions subject to worsening storms and urban flooding due to climate change. Data emerging from prospective surveillance studies suggest that most human leptospiral infections in endemic areas are mild or asymptomatic. Development of more severe outcomes likely depends on three factors: epidemiological conditions, host susceptibility, and pathogen virulence (Fig. 1). Mortality increases with age, particularly in patients older than 60 years of age. High levels of bacteremia are associated with poor clinical outcomes and, based on animal model and in vitro studies, are related in part to poor recognition of leptospiral LPS by human TLR4. Patients with severe leptospirosis experience a cytokine storm characterized by high levels of IL-6, TNF-alpha, and IL-10. Patients with the HLA DQ6 allele are at higher risk of disease, suggesting a role for lymphocyte stimulation by a leptospiral superantigen. Leptospirosis typically presents as a nonspecific, acute febrile illness characterized by fever, myalgia, and headache and may be confused with other entities such as influenza and dengue fever. Newer diagnostic methods facilitate early diagnosis and antibiotic treatment. Patients progressing to multisystem organ failure have widespread hematogenous dissemination of pathogens. Nonoliguric (high output) renal dysfunction should be supported with fluids and electrolytes. When oliguric renal failure occurs, prompt initiation of dialysis can be life saving. Elevated bilirubin levels are due to hepatocellular damage and disruption of intercellular junctions between hepatocytes, resulting in leaking of bilirubin out of bile caniliculi. Hemorrhagic complications are common and are associated with coagulation abnormalities. Severe pulmonary hemorrhage syndrome due to extensive alveolar hemorrhage has a fatality rate of >50 %. Readers are referred to earlier, excellent summaries related to this subject (Adler and de la Peña-Moctezuma 2010; Bharti et al. 2003; Hartskeerl et al. 2011; Ko et al. 2009; Levett 2001; McBride et al. 2005).

Single dosage of doxycycline for prophylaxis against leptospiral infection and leptospirosis during urban flooding in southern Thailand: a non-randomized controlled trial

This study was conducted to investigate the protective efficacy of a single dosage of 200 mg doxycycline against leptospiral infection and leptospirosis and associated risk factors among residents exposed to flooding in southern Thailand. Of 641 participants, 600 received doxycycline while 41 did not. Twenty two participants were infected with Leptospira and six developed leptospirosis. Having a laceration wound was significantly associated with leptospiral infection (odds ratio [OR] = 37.20; P < 0.001) and leptospirosis (OR = 18.24; P = 0.003) whereas exposure to flood more than 3 h per day was associated with only leptospiral infection (OR = 3.70; P = 0.038). Seventeen participants who received doxycycline and five who did not, were infected with Leptospira, resulting a protective efficacy of 76.8% (95% confidence interval [CI] = 34.3%-92.0%). Four who received doxycycline and two who did not, developed leptospirosis, resulting a protective efficacy of 86.3% (CI = -9.8%-98.2%). Among the participants with laceration wound, the protective efficacy for leptospiral infection was 92.0% (CI = 81.2%-96.6%) and for leptospirosis was 95.6% (CI = 78.2%-99.3%). Among the participants exposed to flood water less than or equal to 3 h per day, the protective efficacy for leptospiral infection was 89.2% (95% CI 63.6%-96.67%). A single dosage of 200 mg doxycycline for prophylaxis might be effective for preventing leptospirosis among flood victims with laceration wound after recent flood exposure.

Leptospirosis outbreak following severe flooding: a rapid assessment and mass prophylaxis campaign; Guyana, January-February 2005

BACKGROUND

Leptospirosis is a zoonosis usually transmitted through contact with water or soil contaminated with urine from infected animals. Severe flooding can put individuals at greater risk for contracting leptospirosis in endemic areas. Rapid testing for the disease and large-scale interventions are necessary to identify and control infection. We describe a leptospirosis outbreak following severe flooding and a mass chemoprophylaxis campaign in Guyana.

METHODOLOGY/PRINCIPAL FINDINGS

From January-March 2005, we collected data on suspected leptospirosis hospitalizations and deaths. Laboratory testing included anti-leptospiral dot enzyme immunoassay (DST), immunohistochemistry (IHC) staining, and microscopic agglutination testing (MAT). DST testing was conducted for 105 (44%) of 236 patients; 52 (50%) tested positive. Four (57%) paired serum samples tested by MAT were confirmed leptospirosis. Of 34 total deaths attributed to leptospirosis, postmortem samples from 10 (83%) of 12 patients were positive by IHC. Of 201 patients interviewed, 89% reported direct contact with flood waters. A 3-week doxycycline chemoprophylaxis campaign reached over 280,000 people.

CONCLUSIONS

A confirmed leptospirosis outbreak in Guyana occurred after severe flooding, resulting in a massive chemoprophylaxis campaign to try to limit morbidity and mortality.

Outbreak of leptospirosis after a race in the tropical forest of Martinique

Three athletes who participated in a race in the tropical forest of the Caribbean island of Martinique were subsequently diagnosed with leptospirosis using polymerase chain reaction (PCR). We investigated an outbreak to evaluate possible risk factors, and to determine the appropriate public health recommendations. Of 230 athletes, we contacted 148 (64%) and 20 (13.5%) met our case definition. Five were hospitalized and none were fatal. Ten (91%) of the 11 ill athletes who were tested were confirmed by PCR or serology. Serogroup Pyrogenes was commonly found. Cutaneous cuts, reported by 14 (73.7%), was the only potential risk factor using univariate analysis. Sporting event participants in tropical areas should be made aware of specific warnings and recommendations concerning the risk of leptospirosis, especially after periods of heavy rainfall or flooding. Rapid diagnostic assays such as PCR are particularly appropriate in this setting for early diagnosis and for formulating public health recommendations.

Chemoprophylaxis of Tropical Infectious Diseases

Travelers to tropical countries are at risk for a variety of infectious diseases. In some cases effective vaccinations are available, but for other infections chemoprophylaxis can be offered. Malaria prevention has become increasingly complex as Plasmodium species become resistant to available drugs. In certain high risk settings, antibiotics can be used to prevent leptospirosis, scrub typhus and other infections. Post-exposure prophylaxis is appropriate for selected virulent infections. In this article the evidence for chemoprophylaxis will be reviewed.

WITHDRAWN. Antibiotics for treating leptospirosis

BACKGROUND

Leptospirosis is a parasitic disease transmitted by animals. Severe leptospirosis may result in hospitalisation and about five per cent of the patients die. In clinical practice, penicillin is widely used for treating leptospirosis.

OBJECTIVES

To evaluate the effectiveness and safety of antibiotics versus placebo or other antibiotic regimens in treating leptospirosis. We addressed the following clinical questions: a) Are treatment regimens with antibiotics more efficient than placebo for leptospirosis? b) Are treatment regimens with antibiotics safe when compared to placebo for leptospirosis? c) Which antibiotic regimen is the most efficient and safest in treating leptospirosis?

SEARCH STRATEGY

Electronic searches and searches of the identified articles were combined.

SELECTION CRITERIA

STUDIES

Randomised clinical trials in which antibiotics were used as treatment for leptospirosis. Language, date, or other restrictions were not applied.

PARTICIPANTS

Patients with clinical manifestations of leptospirosis.

INTERVENTIONS

Any antibiotic regimen compared with a control group (placebo or another antibiotic regimen).

DATA COLLECTION AND ANALYSIS

Data and methodological quality of each trial were independently extracted and assessed by two reviewers. The random effects model was used irrespective of significant statistical heterogeneity.

MAIN RESULTS

Three trials met inclusion criteria. Allocation concealment and double blind methods were not clearly described in two. Of the patients enrolled, 75 were treated with placebo and 75 with antibiotics: 61 (81.3%) penicillin and 14 (18.6%) doxycycline. The patients assigned to antibiotics compared to placebo showed: a) Mortality: 1% (1/75) versus 4% (3/75); risk difference -2%, 95% confidence interval -8% to 4%. b) Duration of hospital stay (days): weighted mean difference 0.30, 95% confidence interval -1.26 to 1.86. c) Prolonged hospital stay (> seven days): 30% (7/23) versus 74% (14/19); risk difference -43%, 95% confidence interval -70% to -16%. Number needed-to-treat 3, 95% confidence interval 2 to 7. d) Period of disappearance of fever (days): weighted mean difference -4.04, 95% confidence interval -8.65 to 0.58. e) Leptospiruria: 5% (4/75) versus 40% (30/75); risk difference -46%, 95% confidence interval -88% to -3%. Number needed-to-treat 2, 95% confidence interval 1 to 33.

AUTHORS' CONCLUSIONS

Antibiotic regimens for treatment of leptospirosis is a form of care for which the evidence is insufficient to provide clear guidelines for practice. The randomised trials suggest that antibiotics could be a useful treatment for leptospirosis. Because of the questionable quality of two of the three trials, the indication for general use of antibiotics is uncertain. However, the evidence suggest that penicillin may cause more good than harm.

WITHDRAWN: Antibiotics for preventing leptospirosis

BACKGROUND

Leptospirosis is an infectious disease transmitted by animals. Death occurs in about five per cent of the patients. In clinical practice, doxycycline is widely used for prevention.

OBJECTIVES

To evaluate the effectiveness and safety of any antibiotic regimen versus placebo or other antibiotic regimens in the prophylaxis of leptospirosis.

SEARCH STRATEGY

The sources used were: EMBASE, LILACS, MEDLINE, SCISEARCH, The Cochrane Controlled Trials Register, The Cochrane Hepato-Biliary Group Controlled Trials Register, bibliographies of published papers, and personal communication with authors. There were no language or date restrictions in any of the searches.

SELECTION CRITERIA

STUDIES

All randomised clinical trials in which antibiotics were used as prophylactic regimen for leptospirosis.

PARTICIPANTS

People potentially exposed to leptospirosis, such as people in endemic areas during the rainy season, health professionals and other professionals with high risk of infection.

INTERVENTION

Any antibiotic regimen compared with a control group (placebo or another antibiotic regimen).

OUTCOMES

Infection (primary outcome) and adverse events (secondary outcome).

DATA COLLECTION AND ANALYSIS

Data were independently extracted and methodological quality of each trial was assessed by two reviewers as well as cross-checked. Details of the randomisation (generation and concealment), blinding, and the number of patients lost to follow-up were recorded. The results of each trial were summarised on an intention-to-treat basis in 2 x 2 tables for each outcome.

MAIN RESULTS

Two trials comparing doxycycline with placebo met the inclusion criteria. We did not find trials comparing doxycycline versus other antibiotics, or other antibiotics versus placebo. One of the trials had excellent methodological quality. In the other trial, the allocation concealment process, generation of allocation sequence, and blinding methods were not described.Of the 1022 participants enrolled, 509 were treated with doxycycline and 513 with placebo. Of these, 940 participants were soldiers included in one trial. The patients assigned to the antibiotics group compared with the ones assigned to the placebo group showed: Symptomatic, verified leptospirosis: 0.6% (3/509) versus 4.9% (25/ 513); risk difference (random effects model) -4.1%, 95% confidence interval -5.9% to -2.3%. Number needed-to-treat 24 (95% confidence interval 17 to 43). Adverse effects: 3% (13/469 participants) versus 0.2% (1/471 participants); random effects model 2.6%, 95% confidence interval 1.0% to 4.1%. Number needed-to-harm 39 (95% confidence interval 25 to 100).

AUTHORS' CONCLUSIONS

Prophylaxis of leptospirosis may be achieved by administration of doxycycline to soldiers training in endemic areas with a high risk of exposure to leptospirosis. Whether these findings apply to other scenarios or not remains to be proven.

Antibiotic prophylaxis for leptospirosis

BACKGROUND

Leptospira infection is a global zoonosis with significant health impact for agricultural workers and those persons whose work or recreation takes them into endemic areas.

OBJECTIVES

This systematic review assessed the current literature for evidence for or against use of antibiotic prophylaxis against Leptospira infection (leptospirosis).

SEARCH STRATEGY

The authors searched The Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, MEDLINE, EMBASE, and SCI-Expanded as well as relevant professional society meeting abstracts until January 2009.

SELECTION CRITERIA

Prospective, randomised clinical trials studying antibiotic prophylaxis against leptospirosis were selected.

DATA COLLECTION AND ANALYSIS

Data collection abstracted participant demographics and outcomes as well as features of trial design and quality. Trial results were analysed to independently determine outcomes, while multiple trial data was pooled when relevant.

MAIN RESULTS

Three trials were included, all of which evaluated doxycyline use. Trial quality suffered from a lack of intention-to-treat analysis and variability across trials in methodology and targeted outcomes. One trial assessed post-exposure prophylaxis in an indigenous population after a flood without apparent efficacy in reduction of clinical or laboratory identified Leptospira infection. Two trials assessed pre-exposure prophylaxis, one among deployed soldiers and another in an indigenous population. Despite an odds ratio of 0.05 (95% CI 0.01 to 0.36) for laboratory-identified infection among deployed soldiers on doxycyline in one of these two trials, pooled data showed no statistically significant reduction in Leptospira infection among participants (Odds ratio 0.28 (95% CI 0.01 to 7.48). Minor adverse events (predominantly nausea and vomiting) were more common among those on doxycycline with an odds ratio of 11 (95% CI 2.1 to 60).

AUTHORS' CONCLUSIONS

Regular use of weekly oral doxycycline 200 mg increases the odds for nausea and vomiting with unclear benefit in reducing Leptospira seroconversion or clinical consequences of infection.

Assessing cost effectiveness of empirical and prophylactic therapy for managing leptospirosis outbreaks

This study evaluates the utility and cost effectiveness of empirical and prophylactic antibiotic treatment of leptospirosis compared with conventional management. We developed decision trees comparing empirical antibiotic treatment (within 4-7 days of symptom onset) or prophylaxis to conventional antibiotic treatment (initiated 7 days post-onset). Costs were calculated using both US and Barbados pricing. Empirical treatment provided slightly lower probability of survival, while prophylactic treatment resulted in slightly higher survival rates. Antibiotic treatment initiated after 4-7 symptomatic days was ineffective in preventing serious health outcomes, but cost less with the exception of azithromycin (US pricing). Empirical treatment in Barbados cost less than conventional treatment. Prophylaxis reduced rare serious health outcomes and resulted in significant cost savings for the United States and Barbados. Prophylactic therapy for high-risk individuals or prompt diagnosis and early treatment (before 4 days of symptoms) appear to be cost-effective approaches to prevent severe complications of leptospirosis.

[Severe febrile illness with renal impairment after travel to Southeast Asia]

HISTORY

A 40-year-old teacher fell ill one week after returning from a two weeks back-packing trip to Thailand and Laos. He developed high fever, severe headache, myalgias and a conjunctivitis.

INVESTIGATIONS

CRP and liver enzymes were elevated. The patient developed acute renal failure. Total leucocyte count was normal but the differential count showed an extreme left shift. Imaging procedures revealed hepato-splenomegaly and enlarged kidneys. TREATMENT, COURSE AND DIAGNOSIS: The patient was treated with moxifloxacin and ceftriaxon based on the initial suspicion of a severe infection potentially due to leptospirosis. This treatment led to a rapid improvement of the patient's condition and also of the laboratory findings. Leptospirosis could be confirmed by the seroconversion of specific antibodies to L. grippotyphosa 2 1/2 weeks after onset of complaints (initial serology negative).

CONCLUSIONS

In febrile travelers returning from Southeast Asia, leptospirosis has to be considered especially in case of severe headache, myalgias, elevated liver enzymes and renal failure and a history of close contact to potentially contaminated water (rivers, lakes). Diagnosis is confirmed by the detection of specific antibodies.

Leptospirosis: case reports of an outbreak in Guyana

Although leptospirosis is a globally important zoonotic disease that affects humans on all continents, in both urban and rural areas, it often goes undiagnosed because its clinical manifestations are frequently non-specific. Even when leptospirosis is suspected, confirmation is made difficult by problems in isolating the causative organism in culture and by the low sensitivity of the available serological tests. Following torrential rains and flooding in January-February 2005, an outbreak of leptospirosis was suspected in Guyana, South America. Overall, 108 suspected cases presented at a medical post in the East Coast area of Guyana, and some of these cases are described in detail here. A better understanding of the clinical and paraclinical characteristics of leptospirosis should improve the recognition and appropriate treatment of the disease. Health education could reduce exposure, and physicians and primary healthcare workers could be made more aware of the signs and symptoms of leptospirosis.

Optimal treatment of leptospirosis: queries and projections

Although the global burden of leptospirosis remains enormous and new aspects of the disease are constantly recognised, little progress has been achieved in the field of leptospirosis therapeutics and queries regarding the utility of antibiotics in the late severe form of the disease remain. From the currently existing data, conclusions on the efficacy of antibiotic administration in severe or late disease cannot easily be drawn, since clinical trials have different selection criteria and may focus on Leptospira serovars with different virulence. However, as a rule the benefit of the doubt should apply. Moreover, new options, such as ceftriaxone, have a superior safety profile to penicillin. In vitro studies have outlined potential antimicrobial candidates such as macrolides and ketolides. Development of a globally accepted subunit vaccine for humans is warranted but is not expected in the near future.

Efficacy of macrolides and telithromycin against leptospirosis in a hamster model

Human studies support the use of beta-lactams and tetracyclines in the treatment of leptospirosis. Additional agents from these and other classes of antimicrobials also have in vitro activity against Leptospira species, though corroborating in vivo data are limited or lacking. We evaluated the therapeutic efficacy of azithromycin, clarithromycin, and telithromycin in a lethal hamster model of leptospirosis using Leptospira interrogans serogroup Canicola serovar Portlandvere. A range of dosages for each antimicrobial was given to the infected animals on days 2 through 7 (5 days) of the 21-day survival model. All untreated control animals survived less than 10 days from infection. Ninety to 100% of doxycycline controls, treated for 5 days with 5 mg/kg of body weight of drug, survived to 21 days. Treatment with azithromycin (daily dose: 6.25, 12.5, 25, 50, 100, or 200 mg/kg) resulted in 100% survival at all evaluated doses. Animals receiving 20 mg/kg or more of clarithromycin (daily dose: 1, 5, 10, 15, 20, 40, 60, or 100 mg/kg) had improved survival. Ninety-eight percent of animals treated with telithromycin (daily dose: 1, 5, 10, 15, 20, or 40 mg/kg) survived. We conclude that all agents tested have demonstrated in vivo efficacy in treating acute leptospirosis. These results provide support for further evaluation of macrolide and ketolide antimicrobial agents in human trials.

Prevention and treatment of leptospirosis

Leptospirosis is a common zoonosis acquired by exposure to body fluids, to tissues of infected animals, or to contaminated soil or fresh water. Large outbreaks of leptospirosis have occurred following excess rainfall or in tourists following exposure to fresh water during adventure activities. Prevention may be achieved through the use of protective clothing or by changes in animal husbandry. Immunization is not widely used in human populations but has a role in agriculture. Oral administration of doxycycline (Periostat , CollaGenex) once-weekly can give short-term protection in high-risk environments. The disease in humans has a broad range of symptoms. Treatment may be symptomatic or may require administration of antibiotics, such as doxycycline or penicillin.

The management of leptospirosis

How to quickly identify patients who should be treated for leptospirosis is a challenge. The interest of polymerase chain reaction (PCR) assays is currently being evaluated and rapid tests which can be used outside of the specialised laboratory, have recently been developed. Leptospires are sensitive to many antibiotics and few clinical studies have been made to compare different treatment options. Doxycycline is standard therapy in early leptospirosis treatment and chemoprophylaxis. Intravenous penicillin has been considered the drug of choice in late and severe disease, although it is now challenged by ceftriaxone, which use is easier. Ciprofloxacin may be combined with standard therapy in uveitis. Adjunctive therapies proposed in the management of severe forms of leptospirosis and Jarisch-Herxheimer reactions, are reviewed.

Comparative study of the in-hospital case-fatality rate of leptospirosis between pediatric and adult patients of different age groups

The main objective was to compare the in-hospital case-fatality rate of leptospirosis between pediatric (< 19 years) and adult (>19 years) patients, taking into account gender, renal function, duration of symptoms and jaundice. Medical records of 1016 patients were reviewed. Comparative analysis was restricted to 840 patients (100 pediatric, 740 adults) with recorded information on the variables included in the analysis. Among these patients 81.7% were male and 91.5% were icteric. The case-fatality rate of leptospirosis was 14.4%. The odds of death adjusted for gender, jaundice, duration of symptoms, serum urea and serum creatinine were almost four times higher for the adult than for the pediatric group (odds ratio (OR) = 3.94; 95% confidence interval = 1.19-13.03, p = 0.029). Among adults, increased age was also significantly and independently associated with increased risk of death (p < 0.01). Older patients were also more often treated by dialysis. In conclusion, the data suggest that the in-hospital case fatality rate of leptospirosis is higher for adults than for children and adolescents, even after taking into account the effects of several potential risk factors of death. Among adults, older age was also strongly and independently associated with higher risk of death.

Antibiotics for Travelers: What's Good and What's Not

International travel to exotic destinations continues to increase, as does the risk for illness during travel. Health problems during travel are common. Although many medical problems that travelers incur are noninfectious in origin (eg, injuries, environment-associated illness), travelers often are at risk for acquiring a variety of infections. Many travel-related infections also occur commonly in the developed world, whereas other infections of travelers may be geographically restricted to specific world regions and/or are infrequently encountered in developed nations. Antibiotics play an important role in the treatment and prevention of a variety of bacterial and parasitic infections in travelers. This article reviews antibiotics of particularly high utility to travelers, with emphasis on selected agents that, with appropriate advice from a travel medicine specialist, can be used safely for prophylaxis and self-treatment during travel. The role of antibiotics in selected high-risk travelers also is discussed.

Leptospirosis in "Eco-Challenge" athletes, Malaysian Borneo, 2000

Adventure travel is becoming more popular, increasing the likelihood of contact with unusual pathogens. We investigated an outbreak of leptospirosis in "Eco-Challenge" multisport race athletes to determine illness etiology and implement public health measures. Of 304 athletes, we contacted 189 (62%) from the United States and 26 other countries. Eighty (42%) athletes met our case definition. Twenty-nine (36%) case-patients were hospitalized; none died. Logistic regression showed swimming in the Segama River (relative risk [RR]=2.0; 95% confidence interval [CI]=1.3 to 3.1) to be an independent risk factor. Twenty-six (68%) of 38 case-patients tested positive for leptospiral antibodies. Taking doxycycline before or during the race was protective (RR=0.4, 95% CI=0.2 to 1.2) for the 20 athletes who reported using it. Increased adventure travel may lead to more frequent exposure to leptospires, and preexposure chemoprophylaxis for leptospirosis (200 mg oral doxycycline/week) may decrease illness risk. Efforts are needed to inform adventure travel participants of unique infections such as leptospirosis.

Penicillin at the late stage of leptospirosis: a randomized controlled trial

There is evidence that an early start of penicillin reduces the case-fatality rate of leptospirosis and that chemoprophylaxis is efficacious in persons exposed to the sources of leptospira. The existent data, however, are inconsistent regarding the benefit of introducing penicillin at a late stage of leptospirosis. The present study was developed to assess whether the introduction of penicillin after more than four days of symptoms reduces the in-hospital case-fatality rate of leptospirosis. A total of 253 patients aged 15 to 76 years with advanced leptospirosis, i.e., more than four days of symptoms, admitted to an infectious disease hospital located in Salvador, Brazil, were selected for the study. The patients were randomized to one of two treatment groups: with intravenous penicillin, 6 million units day (one million unit every four hours) for seven days (n = 125) and without (n = 128) penicillin. The main outcome was death during hospitalization. The case-fatality rate was approximately twice as high in the group treated with penicillin (12%; 15/125) than in the comparison group (6.3%; 8/128). This difference pointed in the opposite direction of the study hypothesis, but was not statistically significant (p = 0.112). Length of hospital stay was similar between the treatment groups. According to the results of the present randomized clinical trial initiation of penicillin in patients with severe forms of leptospirosis after at least four days of symptomatic leptospirosis is not beneficial. Therefore, more attention should be directed to prevention and earlier initiation of the treatment of leptospirosis.

Leptospirosis: skin wounds and control strategies, Thailand, 1999

After an outbreak of leptospirosis in workers who participated in cleaning a pond during September 1999 in Thailand, a serologic survey was conducted. Among a cohort of 104 persons from one village who participated in pond cleaning activity, 43 (41.3%) were seropositive for immunoglobulin M antibodies against Leptospira, indicating recent infection. Only 17 (39.5%) of 43 seropositive persons reported a recent febrile illness; the remaining seropositive persons were considered asymptomatic, suggesting that asymptomatic leptospirosis infection may be common where leptospirosis is endemic. Multivariable logistic regression indicated that wearing long pants or skirts was independently protective against leptospirosis infection (OR(adjusted) = 0.217), while the presence of more than two wounds on the body was independently associated with infection (OR(adjusted) = 3.97). Educational efforts should be enhanced in areas where leptospirosis is endemic to encourage the use of protective clothing. In addition, wound management and avoidance of potentially contaminated water when skin wounds are present should be included in health education programs.

Outbreak of leptospirosis among triathlon participants and community residents in Springfield, Illinois, 1998

We investigated an outbreak of leptospirosis among athletes and community residents after a triathlon was held in Springfield, Illinois. A telephone survey was conducted to collect clinical information and data on possible risk factors, community surveillance was established, and animal specimens and lake water samples were collected to determine the source of the leptospiral contamination. A total of 834 of 876 triathletes were contacted; 98 (12%) reported being ill. Serum samples obtained from 474 athletes were tested; 52 of these samples (11%) tested positive for leptospirosis. Fourteen (6%) of 248 symptomatic community residents tested positive for leptospirosis. Heavy rains that preceded the triathlon are likely to have increased leptospiral contamination of Lake Springfield. Among athletes, ingestion of 1 or more swallows of lake water was a predominant risk factor for illness. This is the largest outbreak of leptospirosis that has been reported in the United States. Health care providers and occupational and recreational users of bodies of freshwater in the United States should be aware of the risk of contracting leptospirosis, particularly after heavy rains.

Leptospirosis, water sports, and chemoprophylaxis

Recreational activities, such as water sports and adventure travel, are emerging as an important risk factor for leptospirosis, a potentially fatal zoonosis. We report the clinical course of 2 patients who acquired leptospirosis through participation in water sports. Physicians caring for patients who participate in adventure travel involving water sports should be familiar with the risk factors for and diagnosis, prevention, and treatment of leptospirosis.

Leptospirosis

Leptospirosis is a globally important zoonotic disease that affects humans on all continents, in both urban and rural contexts, and in temperate and tropical climes. Leptospirosis is a disease of the environment; transmission depends on interactions between humans and mammalian reservoir hosts. A variety of infectious diseases that present as undifferentiated febrile syndromes, such as malaria, dengue and influenza, as well as viral hemorrhagic fevers can mimic leptospirosis. The importance of pulmonary hemorrhage as a lethal complication of leptospirosis has become more widely recognized. In contrast to textbook dogma, population-based studies indicate that there is a poor correlation between infecting leptospiral strain and clinical expression of disease. Genetic transformation of a Leptospira sp. has now been reported, which should allow for detailed analysis of a variety of leptospiral genes. Publication of the whole Leptospira genome is eagerly awaited. Following recent reports of a new, highly effective conjugate typhoid vaccine, new efforts to find leptospirosis vaccines should include the manufacture and testing of conjugate leptospiral lipopolysaccharide vaccines. Recent advances, particularly in epidemiology, molecular genetics and pathogenesis, are placing leptospirosis at the cutting edge of biomedical science.

Leptospirosis

Leptospirosis is a worldwide zoonotic infection with a much greater incidence in tropical regions and has now been identified as one of the emerging infectious diseases. The epidemiology of leptospirosis has been modified by changes in animal husbandry, climate, and human behavior. Resurgent interest in leptospirosis has resulted from large outbreaks that have received significant publicity. The development of simpler, rapid assays for diagnosis has been based largely on the recognition that early initiation of antibiotic therapy is important in acute disease but also on the need for assays which can be used more widely. In this review, the complex taxonomy of leptospires, previously based on serology and recently modified by a genotypic classification, is discussed, and the clinical and epidemiological value of molecular diagnosis and typing is also evaluated.

Overview of the epidemiology, microbiology, and pathogenesis of Leptospira spp. in humans

Leptospirosis is probably the world's most widespread zoonosis. It remains underdiagnosed largely due to the broad spectrum of signs and symptoms attributable to this spirochetal pathogen. Leptospira spp. cause a diversity of diseases from flu-like illness to Weil's syndrome with multi-organ failure. Recent epidemics may herald a change in virulence or an alteration in the balance between humans and their interactions with other host species and the environment.

Randomized controlled trial of doxycycline prophylaxis against leptospirosis in an endemic area

Leptospirosis occurs as seasonal outbreaks, lasting for about 3 weeks during October-November in North Andaman. A randomized controlled trial was undertaken to assess the efficacy of doxycycline prophylaxis in the prevention of infection and clinical disease due to leptospires during the outbreak period. A sample population of 782 persons, randomized into two groups was given doxycycline 200 mg/week and a placebo. The microscopic agglutination test was done on blood samples collected on day zero, after 6 weeks and after 12 weeks. Infection rates and attack rates of clinical illness were calculated in the two groups based on the serological results. Statistically there was no difference in the infection rates among the two groups. However, a statistically significant difference was observed in the clinical disease attack rates (3.11 vs. 6.82%) between study group and control group. The results of the study indicate that doxycycline prophylaxis does not prevent leptospiral infection in an endemic area, but has a significant protective effect in reducing the morbidity and mortality during outbreaks.

Antibiotics for preventing leptospirosis

BACKGROUND

Leptospirosis is an infectious disease transmitted by animals. Death occurs in about five per cent of the patients. In clinical practice, doxycycline is widely used for prevention.

OBJECTIVES

To evaluate the effectiveness and safety of any antibiotic regimen versus placebo or other antibiotic regimens in the prophylaxis of leptospirosis.

SEARCH STRATEGY

The sources used were: EMBASE, LILACS, MEDLINE, SCISEARCH, The Cochrane Controlled Trials Register, The Cochrane Hepato-Biliary Group Controlled Trials Register, bibliographies of published papers, and personal communication with authors. There were no language or date restrictions in any of the searches.

STUDIES

All randomised clinical trials in which antibiotics were used as prophylactic regimen for leptospirosis.

PARTICIPANTS

People potentially exposed to leptospirosis, such as people in endemic areas during the rainy season, health professionals and other professionals with high risk of infection.

INTERVENTION

Any antibiotic regimen compared with a control group (placebo or another antibiotic regimen).

OUTCOMES

Infection (primary outcome) and adverse events (secondary outcome).

DATA COLLECTION AND ANALYSIS

Data were independently extracted and methodological quality of each trial was assessed by two reviewers as well as cross-checked. Details of the randomisation (generation and concealment), blinding, and the number of patients lost to follow-up were recorded. The results of each trial were summarised on an intention-to-treat basis in 2 x 2 tables for each outcome.

MAIN RESULTS

Two trials comparing doxycycline with placebo met the inclusion criteria. We did not find trials comparing doxycycline versus other antibiotics, or other antibiotics versus placebo. One of the trials had excellent methodological quality. In the other trial, the allocation concealment process, generation of allocation sequence, and blinding methods were not described. Of the 1022 participants enrolled, 509 were treated with doxycycline and 513 with placebo. Of these, 940 participants were soldiers included in one trial. The patients assigned to the antibiotics group compared with the ones assigned to the placebo group showed: Symptomatic, verified leptospirosis: 0.6% (3/509) versus 4.9% (25/ 513); risk difference (random effects model) -4.1%, 95% confidence interval -5.9% to -2.3%. Number needed-to-treat 24 (95% confidence interval 17 to 43). Adverse effects: 3% (13/469 participants) versus 0.2% (1/471 participants); random effects model 2.6%, 95% confidence interval 1.0% to 4.1%. Number needed-to-harm 39 (95% confidence interval 25 to 100).

REVIEWER'S CONCLUSIONS

Prophylaxis of leptospirosis may be achieved by administrating doxycycline to soldiers training in endemic areas with a high risk of exposure to leptospirosis. Whether these findings apply to other scenarios or not remains to be proven.

Antibiotics for treating leptospirosis

BACKGROUND

Leptospirosis is a parasitic disease transmitted by animals. Severe leptospirosis may result in hospitalisation and about five per cent of the patients die. In clinical practice, penicillin is widely used for treating leptospirosis.

OBJECTIVES

To evaluate the effectiveness and safety of antibiotics versus placebo or other antibiotic regimens in treating leptospirosis. We addressed the following clinical questions: a) Are treatment regimens with antibiotics more efficient than placebo for leptospirosis? b) Are treatment regimens with antibiotics safe when compared to placebo for leptospirosis? c) Which antibiotic regimen is the most efficient and safest in treating leptospirosis?

SEARCH STRATEGY

Electronic searches and searches of the identified articles were combined.

STUDIES

Randomised clinical trials in which antibiotics were used as treatment for leptospirosis. Language, date, or other restrictions were not applied.

PARTICIPANTS

Patients with clinical manifestations of leptospirosis.

INTERVENTIONS

Any antibiotic regimen compared with a control group (placebo or another antibiotic regimen).

DATA COLLECTION AND ANALYSIS

Data and methodological quality of each trial were independently extracted and assessed by two reviewers. The random effects model was used irrespective of significant statistical heterogeneity.

MAIN RESULTS

Three trials met inclusion criteria. Allocation concealment and double blind methods were not clearly described in two. Of the patients enrolled, 75 were treated with placebo and 75 with antibiotics: 61 (81.3%) penicillin and 14 (18.6%) doxycycline. The patients assigned to antibiotics compared to placebo showed: a) Mortality: 1% (1/75) versus 4% (3/75); risk difference -2%, 95% confidence interval -8% to 4%. b) Duration of hospital stay (days): weighted mean difference 0.30, 95% confidence interval -1.26 to 1.86. c) Prolonged hospital stay (> seven days): 30% (7/23) versus 74% (14/19); risk difference -43%, 95% confidence interval -70% to -16%. Number needed-to-treat 3, 95% confidence interval 2 to 7. d) Period of disappearance of fever (days): weighted mean difference -4.04, 95% confidence interval -8.65 to 0.58. e) Leptospiruria: 5% (4/75) versus 40% (30/75); risk difference -46%, 95% confidence interval -88% to -3%. Number needed-to-treat 2, 95% confidence interval 1 to 33.

REVIEWER'S CONCLUSIONS

Antibiotic regimens for treatment of leptospirosis is a form of care for which the evidence is insufficient to provide clear guidelines for practice. The randomised trials suggest that antibiotics could be a useful treatment for leptospirosis. Because of the questionable quality of two of the three trials, the indication for general use of antibiotics is uncertain. However, the evidence suggest that penicillin may cause more good than harm.