An observational study to detect leptospirosis in Mumbai, India, 2000

Laboratory diagnosis and epidemiological features of leptospirosis cases in a tribal region of Western Maharashtra, India: A retrospective study

PURPOSE

Palghar district, located in the coastal region of the Konkan division of Maharashtra, has a predominantly tribal population. Leptospirosis is a major neglected public health problem and is highly underreported in Palghar district. The study aimed to evaluate the seropositivity of Leptospira infection and its associated epidemiological factors in tribal areas of the Palghar district of Maharashtra.

METHODS

The present retrospective study included 94 samples of patients clinically suspected of leptospirosis during a period of one year (2021-2022) tested at Model Rural Health Research Unit (MRHRU) Dahanu. The serum sample testing was done for the presence of specific Leptospira IgM antibodies using the Panbio™ Leptospira IgM ELISA kit. Leptospirosis seropositivity was correlated with various epidemiological risk factors.

RESULTS

A total of 12 samples of patients tested positive for specific IgM antibodies by ELISA method, indicating an overall positivity of 12.8%. Among those who tested positive, fever (83.3%), headache (58.3%), myalgia (50%), redness of the eyes (50%), and calf tenderness (16.7%) were the common symptoms observed. Subjects with redness of the eyes were significantly associated with leptospirosis (p = 0.018). The highest positivity (50%) was reported from the Ganjad area of Dahanu taluka. Farmers and animal handlers were most affected by leptospirosis.

CONCLUSION

The high proportion of Leptospirosis cases reflects the endemic nature of the disease in the Palghar district. This study shows seasonal trends in leptospirosis incidence over the year. The clinical presentation of leptospirosis may vary from sub-clinical to mild illness to severe and potentially fatal. The findings of this study will be important for achieving the overarching goal of One Health.

Leptospirosis in India: a systematic review and meta-analysis of clinical profile, treatment and outcomes

Introduction

Leptospirosis is a zoonotic bacterial infection with significant mortality and morbidity, especially in resource-limited settings. This systematic review aimed to study the clinical profile and outcome of patients with leptospirosis in India.

Methodology

All articles up to 02.08.2022 were searched using the two databases, PubMed and Scopus. A total of 542 articles were found using the search terms related to 'leptospirosis' and 'India'. After two rounds of screening, 55 articles were included. The data were collected on epidemiology, clinical features, laboratory features and treatment of patients with leptospirosis.

Results

Most cases of leptospirosis were reported from the coastal belt. A large percentage of patients were identified as farmers, and exposure to rainfall was identified as an important risk factor. Fever was present in 97%, and conjunctival suffusion was present in 35% of cases. Haemoptysis, gastrointestinal bleeding, and haematuria were present in 5%, 5% and 12% of patients, respectively. Liver and kidney were involved in 34% and 35% of the patients, respectively. The average haemoglobin, leucocyte count and platelet count across various studies ranged from 9.6-12.5 grams/dl, 8.8-11.3 thousand/μl and 20-130 thousand/μl, respectively. Treatment details were sparsely available in some studies, with penicillin, ceftriaxone, and doxycycline used commonly. The pooled mortality across various studies was calculated as 11% [95% CI-8-15%, I2=93%, P<0.001].

Conclusions

Leptospirosis is associated with significant mortality in Indian settings. There is a need for studies focussing on treatment modalities.

Impact of wars and natural disasters on emerging and re-emerging infectious diseases

Emerging Infectious Diseases (EIDs) and Re-Emerging Infectious Diseases (REIDs) constitute significant health problems and are becoming of major importance. Up to 75% of EIDs and REIDs have zoonotic origin. Several factors such as the destruction of natural habitats leading humans and animals to live in close proximity, ecological changes due to natural disasters, population migration resulting from war or conflict, interruption or decrease in disease prevention programs, and insufficient vector control applications and sanitation are involved in disease emergence and distribution. War and natural disasters have a great impact on the emergence/re-emergence of diseases in the population. According to a World Bank estimation, two billion people are living in poverty and fragility situations. Wars destroy health systems and infrastructure, curtail existing disease control programs, and cause population movement leading to an increase in exposure to health risks and favor the emergence of infectious diseases. A total of 432 catastrophic cases associated with natural disasters were recorded globally in 2021. Natural disasters increase the risk of EID and REID outbreaks by damaging infrastructure and leading to displacement of populations. A Generic National Action Plan covering risk assessment, mechanism for action, determination of roles and responsibilities of each sector, the establishment of a coordination mechanism, etc. should be developed.

Demographic and clinical risk factors associated with severity of lab-confirmed human leptospirosis in Colombia, 2015-2020

BACKGROUND

Leptospirosis is a common zoonoses and is a major global public health threat. Most cases are mild, typically presenting as a non-specific acute febrile illness. However, leptospirosis can have life-threatening manifestations, including pulmonary hemorrhage syndrome, and acute kidney injury. In Colombia, notification and lab-confirmation of suspected human cases are mandatory. However, little is known about the demographic and clinical factors associated with severe leptospirosis, which could help to reduce clinical complications and mortality. Our aim was to identify risk factors associated with severe leptospirosis, intensive care unit (ICU) admission, and mortality in lab-confirmed cases in Colombia, 2015-2020.

METHODS AND FINDINGS

We analyzed 201 lab-confirmed human leptospirosis cases by microagglutination test. We used a logistic regression to identify the demographic and clinical risk factors associated with severe leptospirosis, admission to ICU, and death. Most leptospirosis confirmed cases occurred in men (85.6%); the mean age was 36.7 years. We classified severe cases (43.3%) by clinical manifestations as renal (29.9%) and liver (27.4%) failure, multiple-organ failure (24.4%), septic shock (24.4%), Weil syndrome (18.4%), pulmonary hemorrhage (18.4%), and meningitis (2.5%), admitted to the ICU (30.3%), and fatal (8.5%). Clinical conditions associated with severe leptospirosis were dyspnea (OR: 5.54; 95% CI: 1.46 to 20.98), tachycardia (OR:9.69; 95% CI: 15.96 to 58.8), and rash (OR: 10.25; 95% CI: 25.01 to 42.08).

CONCLUSIONS

We identified demographic characteristics and clinical symptoms associated with severe leptospirosis in Colombia. We hope these results can support clinicians in providing timely treatment to leptospirosis patients to avoid preventable medical complications or deaths.

Monitoring of Leptospira species diversity in freshwater bathing area and in rats in Paris, France

Leptospirosis is a neglected zoonotic disease with a worldwide distribution caused by bacterial pathogenic Leptospira. Rodents are considered as the main reservoir of Leptospira and transmission usually occurs through exposure to urine-contaminated environment. However, interactions between environment, rodent reservoir and human leptospirosis remain poorly studied. Here, we evaluated the concentration of Leptospira in surface water and captured rats in the city of Paris (France) from 2018 to 2020 using an integrity qPCR (Quantitative Polymerase Chain Reaction). All environmental samples (n = 1031) were positive for saprophytic Leptospira but pathogenic Leptospira P1 group were only found in 40% (n = 363; 2018) to 0% (n = 264; 2020) of samples. In the same time, analysis of 200 brown rat corpses trapped in the city, showed about 15% of positivity for Leptospira but the different method used for rats conservation (based on presence or absence of conservative agent) showed important variations in the Leptospira prevalence. Metagenomic analysis, based on rrs gene sequencing, was also carried out to evaluate the distribution of Leptospira in samples. Results could indicate that some species of Leptospira are found in surface waters as well as rats, but further study is needed to accurately describe the nature of the link between these two reservoirs. Quantification of Leptospira and pathogenic species description circulating inside animal reservoir living in the vicinity of freshwater in urban areas, will be helpful to understand the eco-epidemiology of leptospirosis and to establish prevention and intervention strategies, especially in the context of organization of recreative activity events in these urban areas.

Clinical profile, management and outcome of patients with leptospirosis during the times of COVID-19 pandemic: A prospective study from a tertiary care centre in South India

Leptospirosis is a rodent-borne acute febrile illness, classically seen after heavy rainfall and floods. This study aimed to describe the clinical profile, management strategies and outcome of patients with leptospirosis amidst the Coronavirus disease-2019 outbreak. A prospective study of adult patients with undifferentiated fever (5-15 days) was conducted in South India between October 2020 and February 2021. The demographic, clinical details, laboratory details, treatment and outcome of leptospirosis positive (based on serology) and negative patients were compared. A chisquare test was used for qualitative variables, while an independent t-test or Mann Whitney U test was used for continuous variables. Of the 206 patients with suspected acute febrile illness, a total of 63 patients were diagnosed with leptospirosis based on serology results. The median sequential organ failure assessment score was higher in those with leptospirosis (p<0.001). Myalgia, abdominal pain, jaundice, decreased urine output, myocarditis, and dialysis requirement were more common in patients with leptospirosis. Leucocytosis and raised procalcitonin/C-reactive protein were more common in patients with leptospirosis. The duration of stay and antibiotic consumption was higher in patients with leptospirosis. Acute febrile illness such as leptospirosis should be suspected in tropical areas with significant risk factors. The presence of conjunctival suffusion, hepatic and renal dysfunction should warrant a serology test for leptospirosis.

Prevention, control and management of leptospirosis in India: an evidence gap map

Leptospirosis is an emerging public health problem in India. We developed an evidence gap map (EGM) on prevention, control and management of leptospirosis in India to inform research priorities. The EGM framework was developed in consultation with stakeholders and noted key parameters to influence state and national level research priorities. We searched six electronic databases and three relevant websites and included 27 studies (humans, 23; animals, 4; both, 0). Most studies (17/27 [63%]) were from three high-burden states. Controlled clinical trials (non-randomised, 6/27 [22%]; randomised, 2/27 [7%]) and pre-post studies (6/27 [22%]) suitable for evaluating interventions were sparse. Only 26% studies (6/23 human studies) included high-risk groups like animal caretakers, tribal people, relief/sanitation workers, pregnant women and people from slums. Nearly 56% of studies (15/27) evaluated pharmacological interventions at an individual level. Community-level interventions were limited (4/27 [15%]) with no studies on vaccination, personal protection, antibiotic policy or water, sanitation and hygiene interventions. Health systems and policy or multicomponent studies were rare (5/27 [19%]) with no reporting of key outcomes like healthcare coverage, quality of care and other relevant outcomes to evaluate interventions. There is a need for prioritising research to evaluate prevention and control interventions, including the One Health approach. Embedding national-level EGMs for research prioritisation exercises should be considered.

Crisis Management Art from the Risks to the Control: A Review of Methods and Directions

A crisis is an exceptional event that causes damage and negative impacts on organizations. For this reason, crisis management is considered as a significant action needed to follow crisis causes and consequences for preventing or avoiding these exceptional events from occurring again. Studies have devoted their efforts to proposing methods, techniques, and approaches in the crisis management direction. As a result, it is critical to provide a consolidated study that has an integrated view of proposed crisis management methods, crisis impacts, and effective response strategies. For this purpose, this paper first highlights the proposed techniques used in crisis management and presents the main objective behind each technique. Second, the risks and impacts resulting from a crisis are highlighted. Finally, crisis response strategies are discussed. The major contribution of this study is it can guide researchers to define research gaps or new directions in crisis management and choose the proper techniques that cope with their research problems or help them discover new research problems.

Public health care system's preparedness to combat epidemics after natural disasters

Disaster management is the execution of various resources and responsibilities that deal with all civilized aspects of tragedies in the consequences of natural or human hazards. There are multiple factors that lead to the outbreak of epidemics after natural disasters, but often the association between natural calamity and the outbreak of epidemics is misconstrued. The health care system of any country has an imperative role in combating the disaster-related epidemics. In developing countries like India, where resources are limited, the public healthcare system plays a vital role against battling epidemics after a natural disaster, hence, preparedness of public health care system to combat epidemics after natural disasters is considered as a narrative review.

Operation Navajeevan: A Public-Private Partnership Model for Disaster Relief in Kozhikode, India

INTRODUCTION

In August 2018, India's southern state of Kerala experienced its worst flooding in over a century. This report describes the relief efforts in Kozhikode, a coastal region of Kerala, where Operation Navajeevan was initiated.

SOURCES

Data were collected from a centralized database at the command center in the District Medical Office as well as first-hand accounts from providers who participated in the relief effort.

OBSERVATIONS

From August 15 through September 8, 2018, 36,846 flood victims were seen at 280 relief camps. The most common cause for presentation was exacerbation of an on-going chronic medical condition (18,490; 50.2%). Other common presentations included acute respiratory infection (7,451; 20.2%), traumatic injuries (3,736; 10.4%), and psychiatric illness (5,327; 14.5%).

ANALYSIS

The prevalence of chronic disease exacerbation as the primary presentation during Operation Navajeevan represents an epidemiologic shift in disaster relief in India. It is foreseeable that as access to health care improves in low- and middle-income countries (LMICs), and climate change increases the prevalence of extreme weather events around the world, that this trend will continue.

A time-trend ecological study for identifying flood-sensitive infectious diseases in Guangxi, China from 2005 to 2012

BACKGROUND

Flood-related damage can be very severe and include health effects. Among those health impacts, infectious diseases still represent a significant public health problem in China. However, there have been few studies on the identification of the spectrum of infectious diseases associated with floods in one area. This study aimed to quantitatively identify sensitive infectious diseases associated with floods in Guangxi, China.

METHODS

A time-trend ecological design was conducted. A descriptive analysis was first performed to exclude infectious diseases with low incidence from 2005 to 2012 in ten study sites of Guangxi. The Wilcoxon rank-sum test was applied to examine the difference in the ten-day attack rate of infectious diseases between the exposure and control periods with different lagged effects. Negative binomial, zero-inflated Poisson and zero-inflated negative binomial models were used to examine the relationship and odd ratios (ORs) of the risk of floods on infectious diseases of preliminary screening.

RESULTS

A total of 417,271 infectious diseases were notified. There were 11 infectious diseases associated with floods in the preliminary screening process for flood-sensitive infectious diseases. The strongest effect was shown with a 0-9 ten-day lag in different infectious diseases. Multivariate analysis showed that floods were significantly associated with an increased the risk of bacillary dysentery (odds ratio (OR) = 1.268, 95% confidence interval (CI): 1.072-1.500), acute haemorrhagic conjunctivitis (AHC, OR = 3.230, 95% CI: 1.976-5.280), influenza A (H₁N₁) (OR = 1.808, 95% CI: 1.721-1.901), tuberculosis (OR = 1.200, 95% CI: 1.036-1.391), influenza (OR = 2.614, 95% CI: 1.476-4.629), Japanese encephalitis (OR = 2.334, 95% CI: 1.119-4.865), and leptospirosis (OR = 1.138, 95% CI: 1.075-1.205), respectively.

CONCLUSION

The spectrum of infectious diseases which are associated with floods are bacillary dysentery, AHC, influenza A (H₁N₁), tuberculosis, influenza, Japanese encephalitis and leptospirosis in Guangxi. Floods can result in differently increased risk of these diseases, and public health action should be taken to control a potential risk of these diseases after floods.

Risk factors for human leptospirosis following flooding: A meta-analysis of observational studies

Leptospirosis is probably the most widespread zoonotic disease in the world especially in tropical countries. There has been an increase in individual studies, which assessed the frequency of leptospirosis in flood conditions. Some studies showed contact with floods was significantly associated with the occurrence of leptospirosis while other studies reported differently. The objective of this meta-analysis was to synthesize the evidence on the risk factors which are associated with human leptospirosis following flooding. We set up the inclusion criteria and searched for the original studies, addressing leptospirosis in human with related to flood in health-related electronic databases including PubMed, Embase, Ovid Medline, google scholar and Scopus sources. We used the terms ‘leptospirosis’, ‘flood’, ‘risk factor’ and terms from the categories were connected with “OR” within each category and by “AND” between categories. The initial search yielded 557 citations. After the title and abstract screening, 49 full-text papers were reviewed and a final of 18 observational studies met the pre-specified inclusion criteria. Overall, the pooled estimates of 14 studies showed that the contact with flooding was a significant factor for the occurrence of leptospirosis (pooled OR: 2.19, 95%CI: 1.48–3.24, I²:86%). On stratification, the strength of association was greater in the case-control studies (pooled OR: 4.01, 95%CI: 1.26–12.72, I²:82%) than other designs (pooled OR:1.77,95%CI:1.18–2.65, I²:87%). Three factors such as ‘being male’(pooled OR:2.06, 95%CI:1.29–2.83), the exposure to livestock animals (pooled OR: 1.95, 95%CI:1.26–2.64), the lacerated wound (pooled OR:4.35, 95%CI:3.07–5.64) were the risk factors significantly associated with the incidence of leptospirosis following flooding in the absence of within-study heterogeneity (I²: 0%). We acknowledge study limitations such as publication bias and type 2 statistical errors. We recommended flood control and other environmental modifications that are expected to reduce the risk of leptospiral infection, and a multi-sectoral effort to this aspect would have long-term benefits.

Environmental and Behavioral Risk Factors for Severe Leptospirosis in Thailand

A nationwide prevention and control campaign for leptospirosis in Thailand has led to a decreased incidence rate, but the mortality and case fatality rates have remained stable. Regarding the limited knowledge of risk factors, a case-control study of the association between environmental and behavioral exposure with severe leptospirosis was implemented to identify the risk factors among adults in Thailand. The study was conducted in 12 hospital-based sites. Hospitalized patients with suspected clinical symptoms of leptospirosis were tested for leptospirosis by culture, loop mediated isothermal amplification (LAMP), real-time PCR, and the microscopic agglutination test (MAT). All participants answered a standardized questionnaire about potential risk factors. Risk factors were identified by univariable and multivariable logistic regression. Of the 44 confirmed cases, 33 (75.0%) presented with severe illness, as determined by clinical criteria, and were categorized as severe cases. Non-severe cases were defined as patients with non-severe symptoms of leptospirosis. Living nearby a rubber tree plantation (adjusted OR 11.65, 95% CI 1.08–125.53) and bathing in natural bodies of water (adjusted OR 10.45, 95% CI 1.17–93.35) were both significantly associated with an increased risk of severe leptospirosis. We recommend designating rubber plantations in Thailand as high-risk zones and closely monitoring hospitalized patients in those areas.

Seroprevalence of leptospiral antibodies among market workers and food handlers in the central state of Malaysia

OBJECTIVE

The high prevalence of leptospirosis in humans is of great public health concern, particularly in tropical and subtropical regions. This study aimed to determine the seroprevalence of leptospiral antibodies and distribution of serovars, and to assess the usefulness of enzyme-linked immunosorbent assay (ELISA) as a screening method for leptospiral antibodies in a high-risk healthy community.

METHODS

Cross-sectional study of 231 market workers and food handlers in wet markets and food premises from two localities in central Malaysia. Respondents' background information was obtained using a questionnaire. Serum samples were tested for leptospiral antibodies using ELISA and microscopic agglutination test (MAT).

RESULTS

Seroprevalence of leptospirosis among healthy workers was 46.3%. Detection of seropositivity was higher by MAT (46%) than ELISA (15%). We observed high seropositivity among local workers (49%), food handlers (49.5%), females (60.8%) and those aged 34 years and older (46.3%). Local strain LEP175 was the predominant serovar, followed by WHO strain Patoc.

CONCLUSION

Overall seroprevalence among healthy food handlers and market workers was high in this study. The workplace places susceptible individuals at risk of leptospirosis.

Leptospirosis in Coastal South India: A Facility Based Study

BACKGROUND

Leptospirosis is a major neglected public health problem and is highly underreported in India. The spectrum of clinical features ranges from subclinical infection to multiorgan failure. The burden of leptospirosis is more in developing countries.

OBJECTIVE

The present study was designed to assess the sociodemographic characteristics, clinical feature, and outcome of leptospirosis patients.

METHODS

This record based retrospective study was conducted in hospitals affiliated to Kasturba Medical College, Mangalore. The registries of the leptospirosis patients during the period of four years between January 2011 and December 2014 were reviewed and the information on demographic and clinical profile of the leptospirosis patients was recorded in the data capture sheet. The information obtained was analyzed using SPSS version 11.5.

RESULTS

The study included 202 leptospirosis victims. The mean age of the study population was 40.48 (±14.8) years. Majority of the patients presented with fever (92.1%) at the time of admission. Acute renal failure was found to be the most common complication (79.2%). Case fatality rate was found to be 3.5%.

CONCLUSION

High proportion of cases indirectly reflects the endemic nature of the disease in the study setting. The clinical presentation of the leptospirosis is highly protean and may vary from a mild illness to life-threatening complications as evident from the current study.

Critical Knowledge Gaps in Our Understanding of Environmental Cycling and Transmission of Leptospira spp

Exposure to soil or water contaminated with the urine of Leptospira-infected animals is the most common way in which humans contract leptospirosis. Entire populations can be at high risk of leptospirosis while working in inundated fields, when engaging in aquatic sports, or after periods of heavy rainfall. The risk of infection after contact with these environmental sources depends on the ability of Leptospira bacteria to survive, persist, and infect new hosts. Multiple variables such as soil and water pH, temperature, and even environmental microbial communities are likely to shape the environmental conditions needed by the pathogen to persist. Here we review what is known about the environmental phase of the infectious Leptospira transmission cycle and identify knowledge gaps that will serve as a guide for future research.

Assessing the performance of remotely-sensed flooding indicators and their potential contribution to early warning for leptospirosis in Cambodia

Remote sensing can contribute to early warning for diseases with environmental drivers, such as flooding for leptospirosis. In this study we assessed whether and which remotely-sensed flooding indicator could be used in Cambodia to study any disease for which flooding has already been identified as an important driver, using leptospirosis as a case study. The performance of six potential flooding indicators was assessed by ground truthing. The Modified Normalized Difference Water Index (MNDWI) was used to estimate the Risk Ratio (RR) of being infected by leptospirosis when exposed to floods it detected, in particular during the rainy season. Chi-square tests were also calculated. Another variable—the time elapsed since the first flooding of the year—was created using MNDWI values and was also included as explanatory variable in a generalized linear model (GLM) and in a boosted regression tree model (BRT) of leptospirosis infections, along with other explanatory variables. Interestingly, MNDWI thresholds for both detecting water and predicting the risk of leptospirosis seroconversion were independently evaluated at -0.3. Value of MNDWI greater than -0.3 was significantly related to leptospirosis infection (RR = 1.61 [1.10–1.52]; χ2 = 5.64, p-value = 0.02, especially during the rainy season (RR = 2.03 [1.25–3.28]; χ2 = 8.15, p-value = 0.004). Time since the first flooding of the year was a significant risk factor in our GLM model (p-value = 0.042). These results suggest that MNDWI may be useful as a risk indicator in an early warning remote sensing tool for flood-driven diseases like leptospirosis in South East Asia.

A Case of Pulmonary Haemorrhage and Acute Kidney Injury 2C01

Leptospirosis is a zoonotic bacterial infection with a reservoir in rodents and farm animals. It is a common disease in tropical countries but rare in the UK. The severe form (Weil's disease) caused by Leptospira is potentially fatal and includes liver failure, renal failure and haemorrhagic pneumonitis. Typical early symptoms of leptospirosis such as myalgia, headache, conjunctivitis and fever may be absent. Careful history-taking for contact with rodents or their excrement and/or farm animals should be performed to identify patients at risk for leptospirosis. Patients with pulmonary haemorrhage and kidney failure should be screened for leptospirosis. Liver failure may be attenuated or delayed by weeks. We describe a case which proved difficult to diagnose.

Climate change & infectious diseases in India: implications for health care providers

Climate change has the potential to influence the earth's biological systems, however, its effects on human health are not well defined. Developing nations with limited resources are expected to face a host of health effects due to climate change, including vector-borne and water-borne diseases such as malaria, cholera, and dengue. This article reviews common and prevalent infectious diseases in India, their links to climate change, and how health care providers might discuss preventive health care strategies with their patients.

The short-term association of temperature and rainfall with mortality in Vadu Health and Demographic Surveillance System: a population level time series analysis

Background

Research in mainly developed countries has shown that some changes in weather are associated with increased mortality. However, due to the lack of accessible data, few studies have examined such effects of weather on mortality, particularly in rural regions in developing countries.

Objective

In this study, we aimed to investigate the relationship between temperature and rainfall with daily mortality in rural India.

Design

Daily mortality data were obtained from the Health and Demographic Surveillance System (HDSS) in Vadu, India. Daily mean temperature and rainfall data were obtained from a regional meteorological center, India Meteorological Department (IMD), Pune. A Poisson regression model was established over the study period (January 2003–May 2010) to assess the short-term relationship between weather variables and total mortality, adjusting for time trends and stratifying by both age and sex.

Result

Mortality was found to be significantly associated with daily ambient temperatures and rainfall, after controlling for seasonality and long-term time trends. Children aged 5 years or below appear particularly susceptible to the effects of warm and cold temperatures and heavy rainfall. The population aged 20–59 years appeared to face increased mortality on hot days. Most age groups were found to have increased mortality rates 7–13 days after rainfall events. This association was particularly evident in women.

Conclusion

We found the level of mortality in Vadu HDSS in rural India to be highly affected by both high and low temperatures and rainfall events, with time lags of up to 2 weeks. These results suggest that weather-related mortality may be a public health problem in rural India today. Furthermore, as changes in local climate occur, adaptation measures should be considered to mitigate the potentially negative impacts on public health in these rural communities.

Infectious diseases following natural disasters: prevention and control measures

Natural disasters may lead to infectious disease outbreaks when they result in substantial population displacement and exacerbate synergic risk factors (change in the environment, in human conditions and in the vulnerability to existing pathogens) for disease transmission. We reviewed risk factors and potential infectious diseases resulting from prolonged secondary effects of major natural disasters that occurred from 2000 to 2011. Natural disasters including floods, tsunamis, earthquakes, tropical cyclones (e.g., hurricanes and typhoons) and tornadoes have been secondarily described with the following infectious diseases including diarrheal diseases, acute respiratory infections, malaria, leptospirosis, measles, dengue fever, viral hepatitis, typhoid fever, meningitis, as well as tetanus and cutaneous mucormycosis. Risk assessment is essential in post-disaster situations and the rapid implementation of control measures through re-establishment and improvement of primary healthcare delivery should be given high priority, especially in the absence of pre-disaster surveillance data.

Associação de variáveis ambientais à ocorrência de leptospirose canina e humana na cidade de São Paulo

Foi realizada uma análise espacial da ocorrência de leptospirose humana e canina na Supervisão de Vigilância em Saúde do Butantã, situada no município de São Paulo, no ano de 2007, associada a variáveis ambientais de risco, tais como: focos de enchente e áreas de desratização. Foram encontrados aglomerados espaciais de pontos de alagamentos em 12 setores censitários e de casos de leptospirose humana em quatro setores censitários, sem correlação entre ambos. Não foram encontrados agrupamentos de casos em cães, possivelmente devido à subnotificação. As proporções casos humanos de leptospirose : população humana dentro e fora da área de desratização foram 7:199.600 e 9:257.980, respectivamente. Conclui-se que medidas de controle de roedores como a desratização foram responsáveis pela minimização dos efeitos dos fatores de risco para a transmissão de leptospirose para humanos.

Prolonged leptospira urinary shedding in a 10-year-old girl

We present a case of leptospirosis in a previously healthy girl following a trip to Costa Rica. While she was clinically asymptomatic, she had spirochetes cultured from her urine six weeks following her trip. Prolonged urinary shedding following infection with Leptospira is possible in humans and often has subtle manifestations in children.

Leptospire genomic diversity revealed by microarray-based comparative genomic hybridization

Comparative genomic hybridization was used to compare genetic diversity of five strains of Leptospira (Leptospira interrogans serovars Bratislava, Canicola, and Hebdomadis and Leptospira kirschneri serovars Cynopteri and Grippotyphosa). The array was designed based on two available sequenced Leptospira reference genomes, those of L. interrogans serovar Copenhageni and L. interrogans serovar Lai. A comparison of genetic contents showed that L. interrogans serovar Bratislava was closest to the reference genomes while L. kirschneri serovar Grippotyphosa had the least similarity to the reference genomes. Cluster analysis indicated that L. interrogans serovars Bratislava and Hebdomadis clustered together first, followed by L. interrogans serovar Canicola, before the two L. kirschneri strains. Confirmed/potential virulence factors identified in previous research were also detected in the tested strains.

Mucocutaneous manifestations of Dengue fever

Dengue viral infection is a cause of considerable morbidity and mortality and may be associated with a variety of mucocutaneous manifestations that may provide important early clues to the diagnosis of this condition. Cutaneous and mucosal findings like confluent erythema, morbilliform eruptions, and hemorrhagic lesions may figure prominently in the clinical features of dengue. The differential diagnoses include a large number of bacterial and viral exanthems as well as drug rash.

Leptospirosis: an emerging disease in travellers

A recent upsurge in leptospirosis in travellers has prompted the following review of the epidemiology of this infection in humans. The available data from the published literature as well as laboratory surveillance were examined to determine the possible causes of the apparent change in epidemiology.

Incidence of leptospirosis in Mazandaran Province, north of Iran: a one year survey

The aim of this study was to provide the first report of incidence of leptospirosis and to determine the epidemiology of this zoonotic disease in Mazandaran Province, North of Iran. In the period of one year, from April 2007 to April 2008, forty seven confirmed reports of human cases of leptospirosis was received by Mazandaran Health Centre from local hospitals and leptospirosis laboratory. The annual incidence rate for the total population was 1.6 per 100,000 person-year. The majority of cases were males (84.1%). The maximum number of cases was seen to occur between 40 and 59 years of age. Seasonal outbreak of leptospirosis was seen in summer (70.3%). Farmers (57.4%) more frequently affected by disease than other occupations. In conclusion, it is necessary for medical practitioner to pay attention to leptospirosis in farmers during summer season.

The kidney in leptospirosis

Leptospirosis is a worldwide zoonosis. Typically, patients are young men, although children can be affected. In children, this disease causes mainly alterations of sensorium. Acute renal failure and jaundice (Weil's syndrome) are less common in children than in adults. The main renal histological findings are acute interstitial nephritis and acute tubular necrosis. Acute renal failure is characterized by hypokalemia and nonoliguria. Many factors are involved in its physiopathology: hypotension, hypovolemia, rhabdomyolysis, hyperbilirubinemia, and, primarily, the direct action of leptospiral proteins. Antibiotic administration (especially early administration) reduces length of hospitalization and leptospiruria. For children, even late antibiotic treatment has been shown to reduce the extent of acute renal failure and thrombocytopenia. Although the best method of dialysis is not yet established, early and intensive dialysis can decrease mortality. Mortality in patients with acute renal failure is approximately 15-20% in association with the presence of oliguria, higher levels of creatinine, and older age. Functional recovery is fast and complete; however, abnormal urinary concentration can persist.

Genetic diversity of the Leptospiral immunoglobulin-like (Lig) genes in pathogenic Leptospira spp

Recent serologic, immunoprotection, and pathogenesis studies identified the Lig proteins as key virulence determinants in interactions of leptospiral pathogens with the mammalian host. We examined the sequence variation and recombination patterns of ligA, ligB, and ligC among 10 pathogenic strains from five Leptospira species. All strains were found to have intact ligB genes and genetic drift accounting for most of the ligB genetic diversity observed. The ligA gene was found exclusively in L. interrogans and L. kirschneri strains, and was created from ligB by a two-step partial gene duplication process. The aminoterminal domain of LigB and the LigA paralog were essentially identical (98.5+/-0.8% mean identity) in strains with both genes. Like ligB, ligC gene variation also followed phylogenetic patterns, suggesting an early gene duplication event. However, ligC is a pseudogene in several strains, suggesting that LigC is not essential for virulence. Two ligB genes and one ligC gene had mosaic compositions and evidence for recombination events between related Leptospira species was also found for some ligA genes. In conclusion, the results presented here indicate that Lig diversity has important ramifications for the selection of Lig polypeptides for use in diagnosis and as vaccine candidates. This sequence information will aid the identification of highly conserved regions within the Lig proteins and improve upon the performance characteristics of the Lig proteins in diagnostic assays and in subunit vaccine formulations with the potential to confer heterologous protection.

A stochastic model for ecological systems with strong nonlinear response to environmental drivers: application to two water-borne diseases

Ecological systems with threshold behaviour show drastic shifts in population abundance or species diversity in response to small variation in critical parameters. Examples of threshold behaviour arise in resource competition theory, epidemiological theory and environmentally driven population dynamics, to name a few. Although expected from theory, thresholds may be difficult to detect in real datasets due to stochasticity, finite population size and confounding effects that soften the observed shifts and introduce variability in the data. Here, we propose a modelling framework for threshold responses to environmental drivers that allows for a flexible treatment of the transition between regimes, including variation in the sharpness of the transition and the variance of the response. The model assumes two underlying stochastic processes whose mixture determines the system's response. For environmentally driven systems, the mixture is a function of an environmental covariate and the response may exhibit strong nonlinearity. When applied to two datasets for water-borne diseases, the model was able to capture the effect of rainfall on the mean number of cases as well as the variance. A quantitative description of this kind of threshold behaviour is of more general application to predict the response of ecosystems and human health to climate change.

The exanthem of dengue fever: Clinical features of two US tourists traveling abroad

BACKGROUND

Dengue fever is the most common identifiable cause of acute febrile illness among travelers returning from South America, South Central Asia, Southeast Asia, and the Caribbean. Although the characteristic exanthem of dengue fever occurs in up to 50% of patients, few descriptions of it are found in the dermatology literature, and discussions of how to distinguish the dengue exanthem from other infectious disease entities are rare. Chikungunya fever is an emerging infectious disease now seen in returning US tourists and should be considered in the differential diagnosis of dengue fever in the appropriate patient.

OBJECTIVE

The purpose of our study was to report two cases of dengue fever among returning US tourists, provide a review of dengue fever, offer an extensive differential diagnosis of dengue fever, and raise awareness among dermatologists of chikungunya fever.

METHODS

This study includes clinical findings of two returning travelers, one who traveled to Mexico and the other to Thailand, complemented by a discussion of both dengue fever and its differential diagnosis.

LIMITATIONS

Limited to 2 case reports.

CONCLUSION

Dengue fever should be considered in the differential diagnosis of fever and rash in the returning traveler. Dermatologists should be aware of the distinctive exanthem of dengue fever. Recognition of the dengue fever rash permits a rapid and early diagnosis, which is critical, as dengue fever can progress to life-threatening dengue hemorrhagic fever or dengue shock syndrome.

The globalization of leptospirosis: worldwide incidence trends

OBJECTIVES

Leptospirosis continues to be a significant zoonosis of the developing world. Globalization, in the context of international travel, particularly for recreational activities and military expeditions, has led to increased exposure of individuals from the developed world to the disease, as recent outbreaks show.

METHODS

We evaluated the trends in annual leptospirosis incidence for individual countries worldwide through reports from national and international organizations, the published medical literature on the subject, and web searches with the terms 'leptospirosis' and the individual country names. Inter-country variations in leptospirosis incidence, when relevant official data were available, were also analyzed.

RESULTS

The Caribbean and Latin America, the Indian subcontinent, Southeast Asia, Oceania, and to a lesser extent Eastern Europe, are the most significant foci of the disease, including areas that are popular travel destinations.

CONCLUSIONS

Leptospirosis is a re-emerging zoonosis of global importance and unique environmental and social correlations. Attempts at global co-ordination and recognition of the true burden of an infectious disease with significant mortality should be encouraged.

Epidemics after natural disasters

The relationship between natural disasters and communicable diseases is frequently misconstrued. The risk for outbreaks is often presumed to be very high in the chaos that follows natural disasters, a fear likely derived from a perceived association between dead bodies and epidemics. However, the risk factors for outbreaks after disasters are associated primarily with population displacement. The availability of safe water and sanitation facilities, the degree of crowding, the underlying health status of the population, and the availability of healthcare services all interact within the context of the local disease ecology to influence the risk for communicable diseases and death in the affected population. We outline the risk factors for outbreaks after a disaster, review the communicable diseases likely to be important, and establish priorities to address communicable diseases in disaster settings.

High serum nitric oxide levels in patients with severe leptospirosis

Leptospirosis is a globally distributed zoonosis of major public health importance and is associated with severe disease manifestations such as acute renal failure and pulmonary haemorrhage syndrome. However, the extent to which the pathogenesis of leptospirosis mimics sepsis caused by Gram-negative bacteria remains unknown. The aim of this study was to evaluate serum levels of nitric oxide (NO) in patients diagnosed with severe leptospirosis. Sera from 35 confirmed cases of severe leptospirosis and 13 healthy subjects were analysed. Patients with severe leptospirosis had significantly higher NO levels compared to healthy individuals (30.82+/-10.90 microM versus 3.86+/-1.34 microM, P < 0.001), indicating that this immune mediator plays a role in the underlying systemic inflammatory response.

Leptospirosis in Istanbul, Turkey: a wide spectrum in clinical course and complications

Patients with high fever and multiorgan involvement were investigated for the determination of frequency, clinical course and complications of leptospirosis in Istanbul. Leptospirosis was determined in 22 cases among the 35 hospitalized patients that were pre-diagnosed as leptospirosis according to 'Probable Leptospirosis Diagnosis and Follow-up' form. Among the leptospirosis cases 19 were male and 16 were military staff. Mean age was 35.6 y. Dark field examination (DFE), latex agglutination test (LAG), ELISA IgM, leptospirosis culture (LC) and microscopic agglutination test (MAT) were performed to confirm the diagnoses. The most frequent initial symptoms and findings were fever, fatigue, headache, nausea-vomiting and increased muscle sensitivity. Jaundice was noted only in 2 cases. A 74-y-old female patient died after the recurrence of the disease with severe rhabdomyolysis and pulmonary failure. Sagittal sinus thrombosis, perimyocarditis and chronic renal failure were major complications in another 3 patients. ELISA IgM, LC, DFE, LAG and MAT tests were positive in 68, 72, 82, 100 and 100% of the patients, respectively. As a conclusion, diagnosis of leptospirosis is usually overlooked. Clinical awareness, use of probable leptospirosis diagnosis forms and the application of different laboratory methods in the diagnosis of suspected cases may offer the chance to diagnose the leptospirosis accurately.

Leptospirosis

PURPOSE OF REVIEW

Leptospirosis, a spirochaetal zoonotic disease, has been recognized as an important emerging infectious disease in the last 10 years. This review addresses the issues in the epidemiology, diagnosis and clinical management which confront public health responses, and highlights the progress made towards understanding the Leptospira genome, biology and pathogenesis.

RECENT FINDINGS

Leptospirosis has spread from its traditional rural base to become the cause of epidemics in poor urban slum communities in developing countries. Mortality from severe disease forms, Weil's disease and severe pulmonary haemorrhage syndrome, is high (>10% and >50%, respectively) even when optimal treatment is provided. Moreover, the overall disease burden is underestimated, since leptospirosis is a significant cause of undifferentiated fever and frequently not recognized. Barriers to addressing this problem have been the lack of an adequate diagnostic test and effective control measures. China and Brazil, countries in which leptospirosis is a major health problem, have completed the sequence of the Leptospira interrogans genome. Together with new genetic tools and proteomics, new insights have been made into the biology of Leptospira and the mechanisms used to adapt to host and external environments. Surface-exposed proteins and putative virulence determinants have been identified which may serve as sub-unit vaccine candidates.

SUMMARY

Major progress has been made in the basic research of leptospirosis. Future challenges will be to translate these advances into public health measures for developing countries. Yet the most effective responses may be interventions that directly address the determinants of poverty, such as poor sanitation, which are often responsible for transmission.

Leptospirosis during dengue outbreak, Bangladesh

We collected acute-phase serum samples from febrile patients at 2 major hospitals in Dhaka, Bangladesh, during an outbreak of dengue fever in 2001. A total of 18% of dengue-negative patients tested positive for leptospirosis. The case-fatality rate among leptospirosis patients (5%) was higher than among dengue fever patients (1.2%).