Molecular epidemiology of leptospirosis in northern Iran by nested polymerase chain reaction/restriction fragment length polymorphism and sequencing methods

Epidemiological Features of Leptospirosis and Identification of Leptospira wolffii as a Persistently Prevailing Species in North-Central Bangladesh

Leptospirosis is considered to be the most widespread, yet neglected, re-emerging zoonotic disease caused by infection with a pathogenic species of the genus Leptospira. Although this disease is prevalent in Bangladesh, the recent epidemiological status has not yet been well documented. In this study, we aimed to determine the prevalence of leptospirosis among febrile patients using different diagnostic methods and to characterize the epidemiological features and species of Leptospira in Mymensingh, north-central Bangladesh. Among the blood samples of 186 patients with suspected leptospirosis who met the inclusion criteria, including having a fever for more than 5 days (November 2021-June 2022), 88 samples (47%) were Leptospira-positive according to IgM LAT, IgM ELISA, or nested PCR (positivity rates: 38%, 37%, and 42%, respectively). Nested PCR showed a significantly higher positivity rate (54%) in patients with a short fever (5-10 day) than the other methods did, with lower rates among those with a longer fever. Leptospirosis cases were more common in males (68%), those 16-45 years of age (70%), residents of rural areas (81%), and farmers (41%). In addition to a fever, myalgia and jaundice were found in more than 70% of the patients, while variable symptoms were observed. The 16S rRNA sequencing analysis revealed that the Leptospira species in all the 22 samples tested were L. wolffii, belonging to the pathogenic subclade P2. This study showed the recent epidemiological features of leptospirosis in Bangladesh, indicating the presumptive predominance of L. wolffii since 2019.

Epidemiology of Leptospirosis: The First Literature Review of the Neglected Disease in the Middle East

Leptospirosis is a major zoonotic disease that has emerged worldwide, and numerous studies performed in affected countries have provided epidemiological knowledge of the disease. However, currently, there is inadequate knowledge of leptospirosis in the Middle East. Therefore, we grouped publications from various Middle Eastern countries to acquire a general knowledge of the epidemiological situation of leptospirosis and provide an initial description of the leptospiral relative risk and circulating serogroups. We conducted a detailed literature search of existing studies describing Leptospira prevalence and seroprevalence in Middle Eastern countries. The search was performed using online PubMed and ScienceDirect databases. One hundred and one articles were included in this review. Some countries, including Iran, Turkey, and Egypt, reported more publications compared to others, such as Lebanon, Kuwait, and Saudi Arabia. Frequently, the seroprevalence of leptospirosis varied considerably between and within countries. The prevalence of leptospirosis was comparable in most Middle Eastern countries; however, it varied between some countries. The methods of detection also varied among studies, with the microscopic agglutination test used most commonly. Some hosts were more recurrent compared with others. This review summarizes the epidemiological situation of Leptospira infection in the Middle East, reporting predominant serogroups-Sejroe, Grippotyphosa, Icterohaemorrhagiae, Autumnalis, and Pomona-that were identified in the most commonly tested hosts. Our findings emphasize the need to develop a deeper understanding of the epidemiology of Leptospira spp. and prioritize the disease as a public health problem in this region. To achieve this goal, increased awareness is critical, and more publications related to the topic and following a standardized approach are needed.

Regional Prevalence of Intermediate Leptospira spp. in Humans: A Meta-Analysis

Leptospirosis is one of the most widespread bacterial diseases caused by pathogenic Leptospira. There are broad clinical manifestations due to varied pathogenicity of Leptospira spp., which can be classified into three clusters such as pathogenic, intermediate, and saprophytic. Intermediate Leptospira spp. can either be pathogenic or non-pathogenic and they have been reported to cause mild to severe forms of leptospirosis in several studies, contributing to the disease burden. Hence, this study aimed to estimate the global prevalence of intermediate Leptospira spp. in humans using meta-analysis with region-wise stratification. The articles were searched from three databases which include PubMed, Scopus, and ScienceDirect. Seven studies were included consisting of two regions based on United Nations geo-scheme regions, among 469 records identified. Statistical analysis was performed using RevMan software. The overall prevalence estimate of intermediate Leptospira spp. in humans was 86% and the pooled prevalences were 96% and 17% for the American and Asia regions, respectively. The data also revealed that Leptospira wolffii was the most predominantly found compared to the other intermediate species identified from the included studies, which were Leptospira inadai and Leptospira broomii. The estimated prevalence data from this study could be used to develop better control and intervention strategies in combating human leptospirosis.

Predominance of Leptospira wolffii in north-central Bangladesh, 2019

Leptospira was detected in 48.9% of blood samples from 182 febrile patients in north-central Bangladesh in 2019. Most Leptospira were classified as L. wolffii (93%) on the basis of phylogenetic analysis of 16S ribosomal RNA genes, while others were assigned to L. borgpetersenii and L. meyeri.

Low Prevalence of Leptospira Carriage in Rodents in Leptospirosis-Endemic Northeastern Thailand

Leptospirosis is a neglected zoonotic disease affecting mostly the world's tropical regions. The rural people of northeastern Thailand suffer from a large number of leptospirosis infections, and their abundant rice fields are optimal rodent habitats. To evaluate the contribution of diversity and carriage rate of pathogenic Leptospira in rodent reservoirs to leptospirosis incidence, we surveyed rodents, between 2011 and 2012, in four provinces in northeastern Thailand with the highest incidence rates of human leptospirosis cases. We used lipL32 real-time PCR to detect pathogenic Leptospira in rodent kidneys, partial 16S rRNA gene sequencing to classify the infecting Leptospira species, and whole 16S rDNA sequencing to classify species of isolated Leptospira. Overall prevalence of Leptospira infection was 3.6% (18/495). Among infected rodents, Bandicotaindica (14.3%), Rattusexulans (3.6%), and R. rattus (3.2%) had renal carriage. We identified two pathogenic Leptospira species: L. interrogans (n = 15) and L. borgpetersenii (n = 3). In addition, an L. wolffii (LS0914U) isolate was recovered from the urine of B. indica. Leptospira infection was more prevalent in low density rodent populations, such as B. indica. In contrast, there was a lower prevalence of Leptospira infection in high density rodent populations of R. exulans and R. rattus.

Infection of hard ticks in the Caspian Sea littoral of Iran with Lyme borreliosis and relapsing fever borreliae

The Caspian Sea littoral of Iran is home to various hard tick species, including Ixodes ricinus, the notorious vector of Lyme borreliosis (LB) in Eurasia. Here, in this area, we examined I. ricinus and other hard ticks, along with common rodents and small mammals for LB and relapsing fever (RF) borreliae infection. Ticks were collected from various mammalian hosts, including sheep, goats, cattle, camels, horses, dogs, donkeys, rodents, and hedgehogs. Rodents and small mammals were live-captured from different habitats. A real-time PCR for 16S rRNA sequence revealed borrelial DNA in 71 out of 501 (≈14 %) specimens belonging to I. ricinus and Rhipicephalus ticks. None of the rodents and small mammals showed borrelial infection in the viscera. PCR amplification and sequencing of a 600-bp sequence of the flaB identified Borrelia bavariensis, Borrelia garinii, Borrelia afzelii, and Borrelia valaisiana, and the RF Borrelia, B. miyamotoi in I. ricinus ticks. The RF-like Borrelia in Rhipicephalus ticks shared the highest identity (98.97 %) with an isolate infecting Haemaphysalis megaspinosa ticks in Japan. Our phylogeny and BLAST analysis suggest the range extension of the European I. ricinus-associated borreliae into the north of Iran.

Impacts of flood on health of Iranian population: Infectious diseases with an emphasis on parasitic infections

Background

Outbreaks of infectious diseases are the major concern after flooding. Flood makes people displacement which would be more complicated with inadequate sanitation. Settling in crowded shelters in absence of clean water and inaccessibility to health care services makes people more vulnerable to get infection. This review aimed to discuss about potential undesirable outcomes of flooding occurred in 2019 in Iran.

Methods

A comprehensive search was carried out in databases including PubMed, Google scholar, Scopus, Science Direct, Iran medex, Magiran and SID (Scientific information database) from 2000 to 2019. All original descriptive articles on flood were concerned. Related articles on flood disturbance were considered. Also, publication of red cross society was considered as only reliable reference in evaluation of consequences of flood occurred in 2019 in Iran.

Results

Flooding in Iran, was started in March 2019 and lasted to April 2019. Flood affected 31 provinces and 140 rivers burst their banks, and southwestern Iran being hit most severely. According the reports of international federation of red cross society, 3800 cities and villages were affected by the floods with 65,000 destroyed houses and 114,000 houses partially damaged. Also 70 hospitals or health care centers with 1200 schools were damaged along with many infrastructures including 159 main roads and 700 bridges.

Conclusions

Considering 365,000 displaced persons and estimation of mentioned damages, it was one of the greatest natural disaster during the last 20 years. Various risk factors in favor of infectious diseases such as overcrowding, disruption of sewage disposal, poor standards of hygiene, poor nutrition, negligible sanitation and human contact among refugees provide suitable conditions for increased incidence of infectious diseases after flooding and also cause epidemics.More attention is needed to provide hygienic situation for people after natural disasters including flood.

Prediction mapping of human leptospirosis using ANN, GWR, SVM and GLM approaches

Background

Recent reports of the National Ministry of Health and Treatment of Iran (NMHT) show that Gilan has a higher annual incidence rate of leptospirosis than other provinces across the country. Despite several efforts of the government and NMHT to eradicate leptospirosis, it remains a public health problem in this province. Modelling and Prediction of this disease may play an important role in reduction of the prevalence.

Methods

This study aims to model and predict the spatial distribution of leptospirosis utilizing Geographically Weighted Regression (GWR), Generalized Linear Model (GLM), Support Vector Machine (SVM) and Artificial Neural Network (ANN) as capable approaches. Five environmental parameters of precipitation, temperature, humidity, elevation and vegetation are used for modelling and predicting of the disease. Data of 2009 and 2010 are used for training, and 2011 for testing and evaluating the models.

Results

Results indicate that utilized approaches in this study can model and predict leptospirosis with high significance level. To evaluate the efficiency of the approaches, MSE (GWR = 0.050, SVM = 0.137, GLM = 0.118 and ANN = 0.137), MAE (0.012, 0.063, 0.052 and 0.063), MRE (0.011, 0.018, 0.017 and 0.018) and R² (0.85, 0.80, 0.78 and 0.75) are used.

Conclusion

Results indicate the practical usefulness of approaches for spatial modelling and predicting leptospirosis. The efficiency of models is as follow: GWR > SVM > GLM > ANN. In addition, temperature and humidity are investigated as the most influential parameters. Moreover, the suitable habitat of leptospirosis is mostly within the central rural districts of the province.

First molecular identification of two Leptospira species (Leptospira interrogans and Leptospira wolffii) in Bangladesh

Leptospiral 16S rRNA genes were detected in 13 blood samples from 74 febrile patients in north-central Bangladesh, and their sequences phylogenetically clustered with those of Leptospira interrogans or Leptospira wolffii. Genetic diversity in O-antigen polymerase (wzy) was found in an L. interrogans sample.

Leptospirosis: a diagnostic conundrum

Leptospirosis is a serious public health concern worldwide. It is highly endemic in the Andaman Islands and its prevalence is increasing in other Indian states. Clinical features are non-specific and diagnosis relies on laboratory confirmation. The gold standard is microscopic agglutination testing, but this is not widely available. Real-time polymerase chain reaction testing of LipL32 antigen provides the earliest detection of pathogenic Leptospira in the body. We found it to be 100% specific, but it should be used in the first 10 days of illness for reliable results.

Leptospirosis in Caspian Sea littoral, Gilan Province, Iran

In Iran, leptospirosis is endemic to Caspian Sea littoral. The disease appears as a seasonal infection mostly affecting people in rural areas involved in farming. We investigated the prevalence of this infection among suspected patients in Gilan Province by an indirect immunofluorescent assay (IFA), and two PCR protocols, a nested-PCR and a real-time PCR (qPCR), targeting rrs and lipL32 genes, respectively. We also identified the common Leptospira species by sequencing a partial sequence of rrs gene. Out of the 128 sera examined by IFA, 25.78% were positive with the antibody titers ≥1/80. The antibody titer in 39.06% of sera ranged from 1/10 to 1/140, and 35. 16% showed no antibodies, all considered negative. Nested PCR and qPCR detected Leptospira DNA in 20.31% and 18.75% of the sera, respectively. The two PCR assays had 98.43% agreement (K = 0.93) and showed an inverse correlation with the IFA titers. Also, three pathogenic Leptospira species, L. kirschneri (n = 10), L. introgans (n = 8), and L. borgpetersenii (n = 2) were identified from the clinical specimens in the study area. In our hands both PCR assays proved very efficient for early diagnosis of illness and could be used in combination with IFA for both diagnosis and epidemiological studies, but nested PCR was cheaper and appeared more appropriate for our laboratories in rural settings.

Emerging and re-emerging infectious diseases in Iran

Despite development of preventive and controlling strategies regarding infectious diseases, they are still considered as one of the most significant leading causes of morbidity and mortality, worldwide. Changes in humans' demographics and behaviors, microbial and ecological alterations, agricultural development, international travels and susceptibility to infectious diseases have resulted in increased reports of emerging infectious diseases (EIDs) and reemerging infectious diseases (RIDs) in various geographical areas. Because of the various types of geographic properties in Iran, substantial climatic variability, as well as unstable political situations and poor public health conditions in some of neighboring countries, EIDs and RIDs are serious public health problems; among them, zoonotic and drug resistant diseases are the most significant. Hence, this review provides an overview of the significant bacterial, viral and fungal EIDs and RIDs in Iran regarding their epidemiological aspects.

Serological survey of leptospirosis among different groups in western Iran

Leptospirosis is a zoonosis and a major public health problem. Blood sampling was done in the province of Kurdistan from 250 members of different groups, including hunters and their families, butchers and slaughterhouse workers, healthcare workers (HCWs) and those referred to medical diagnostic laboratories for routine testing. Sera were tested using an ELISA method to detect specific Leptsopira IgG antibodies. We found 20.80% (95% confidence interval, 16.23-26.25%) to be positive. The highest and lowest seroprevalence were in hunters (26%) and HCWs (18%). There was significant positive correlation between age and seropositivity ( P = 0.01). Hunting and eating the meat of the hare and exposure to dead or dying wild animals were found to be the main risk factors ( P < 0.05).

Human leptospirosis in Tanzania: sequencing and phylogenetic analysis confirm that pathogenic Leptospira species circulate among agro-pastoralists living in Katavi-Rukwa ecosystem

BACKGROUND

Leptospirosis is a neglected zoonotic disease of worldwide public health importance. The disease affects humans, domestic animals and wildlife. However, leptospirosis is challenging in its diagnosis in humans. Culture technique, which is time consuming, is not recommended for clinical diagnosis. For these reasons, serological and molecular techniques remain the test of choice. The major objective of this study was to explore the genetic characteristic of Leptospira species which are prevalent among agro-pastoralists living in Katavi-Rukwa Ecosystem, Tanzania.

METHODS

A cross-sectional epidemiological study was carried out in the Katavi-Region South-west, Tanzania between August, 2013 and November, 2014. A total of 267 participants were randomly recruited for the study. Microscopic agglutination test (MAT) was used to detect antibody against six Leptospira antigens including local serogroups Icterohaemorrhagiae, Ballum, Grippotyphosa, Sejroe and reference serogroups Hebdomadis, and Australis. Samples with MAT titers ≥ 1:160 were scored as positive, samples with MAT titers ranging from 1:20 to 1:80 were scored as exposed to Leptospira, and absence of agglutination titers was scored as negative. All MAT positive samples, including the low titre samples were subjected to PCR using the respective 16S rRNA primers for the pathogenic and non-pathogenic species.

RESULTS

Out of 267 samples tested, 80 (29.9 %) were positive with MAT. The major circulating leptospiral serogroups were Sejroe (15.7 %,), Icterohaemorrhagiae (8.9 %), Grippotyphosa (4.8 %), Hebdomadis (3.37 %), Australis (1.49 %) and Ballum (1.19 %). By using PCR, 33 (15.7 %) out of 210 samples were pathogenic Leptospira while no saprophytic Leptospira spp. was detected. Partial 16S rRNA gene sequences of Leptospira species which were obtained from this study were submitted to GenBank and acquired accession numbers KP313246 and KP313247. Phylogenetic analysis of the nucleotide sequences revealed that species obtained from Katavi-Rukwa ecosystem clustered in the same group with several published pathogenic Leptospira specifically Leptospira interrogans and Leptospira kirschneri. To the best of the authors' knowledge(,) this is the first study from Tanzania to confirm pathogenic Leptospira in human subjects using genomic typing technique.

CONCLUSION

These findings provide ultimate evidence of pathogenic Leptospira species circulating among agro-pastoralists living in Katavi-Rukwa Ecosystem suggesting that active disease surveillance should be undertaken in order to achieve greater protection of the agro-pastoral communities in Tanzania.

Seroprevalence of Brucellosis, Leptospirosis, and Q Fever among Butchers and Slaughterhouse Workers in South-Eastern Iran

Zoonotic diseases can be occupational hazards to people who work in close contact with animals or their carcasses. In this cross-sectional study, 190 sera were collected from butchers and slaughterhouse workers in different regions of the Sistan va Baluchestan province, in Iran in 2011. A questionnaire was filled for each participant to document personal and behavioural information. The sera were tested for detection of specific IgG antibodies against brucellosis, leptospirosis, and Q fever (phase I and II) using commercial enzyme-linked immunosorbent assays (ELISA). The seroprevalence of brucellosis was 7.9%, leptospirosis 23.4%, and phase I and II of Q fever were 18.1% and 14.4%, respectively. The seroprevalence of Q fever and leptospirosis, but not brucellosis, varied among regions within the province (p = 0.01). Additionally, a significant relationship was found between seropositivity of Q fever and camel slaughtering (p = 0.04). Reduced seropositivity rate of brucellosis was associated with use of personal protective equipment (PPE) (p = 0.004). This study shows that brucellosis, leptospirosis and Q fever occur among butchers and slaughterhouse workers in this area.

Genetic variation of Leptospira isolated from rats catched in Yogyakarta Indonesia

OBJECTIVE

To detect genetic variations among pathogenic Leptospira isolated from rats using 16S rRNA gen as chronometer.

METHODS

This is an observational study with cross sectional design. Rats samples were taken in Yogyakarta Special Region of Indonesia. Leptospira in the rats was detected by two methods i.e. real time PCR (qPCR) by using primers correspond to16S rRNA gene of Leptospira, and standard PCR by using different set of primer correspond to the 16S rRNA gene of Leptospira. The standard PCR amplicon then subjected for DNA sequencing. Analysis genetic variation was performed using MEGA 6.2. Software.

RESULTS

There were 99 DNA samples from rats included in this study. Detection of Leptospira by using qPCR revealed 25 samples positive for pathogenic Leptospira, while only 6 samples were able to be detected using standard PCR. The new primer set correspond to 16S rRNA gene was able to detect specifically pathogenic Leptospira in the rats. Sequencing analysis of 6 PCR amplicons showed that the Leptospira which infect the rats catched in Yogyakarta genetically close related with pathogenic Leptospira which were isolated from human, animal, rodents, and environment.

CONCLUSIONS

It can be considered that rats are the most important vector and reservoir of Leptospira.

Molecular characterisation and disease severity of leptospirosis in Sri Lanka

Leptospirosis is a re-emerging zoonotic disease all over the world, important in tropical and subtropical areas. A majority of leptospirosis infected patients present as subclinical or mild disease while 5-10% may develop severe infection requiring hospitalisation and critical care. It is possible that several factors, such as the infecting serovar, level of leptospiraemia, host genetic factors and host immune response, may be important in predisposition towards severe disease. Different Leptospira strains circulate in different geographical regions contributing to variable disease severity. Therefore, it is important to investigate the circulating strains at geographical locations during each outbreak for epidemiological studies and to support the clinical management of the patients. In this study immunochromatography, microscopic agglutination test and polymerase chain reaction were used to diagnose leptospirosis. Further restriction fragment length polymorphism and DNA sequencing methods were used to identify the circulating strains in two selected geographical regions of Sri Lanka. Leptospira interrogans, Leptospira borgpetersenii and Leptospira kirschneri strains were identified to be circulating in western and southern provinces. L. interrogans was the predominant species circulating in western and southern provinces in 2013 and its presence was mainly associated with renal failure.

An epidemiological comparative study on diagnosis of rodent leptospirosis in Mazandaran Province, northern Iran

OBJECTIVES:

Leptospirosis is a zoonosis caused by leptospires, in which transmission occurs through contact with contaminated biological fluids from infected animals. Rodents can act as a source of infection for humans and animals. The disease has a global distribution, mainly in humid, tropical and sub-tropical regions. The aim of this study was to compare culture assays, the microscopic agglutination test (MAT), polymerase chain reaction (PCR), and nested PCR (n-PCR), for the diagnosis of leptospirosis in rodents in Mazandaran Province, northern Iran.

METHODS:

One hundred fifty-one rodents were trapped alive at 10 locations, and their urine and kidney samples were collected and used for the isolation of live Leptospira. The infecting serovars were identified and the antibody titres were measured by MAT, using a panel of 20 strains of live Leptospira species as antigens. The presence of leptospiral DNA was evaluated in urine and kidney samples using PCR and n-PCR.

RESULTS:

No live leptospires were isolated from the kidney and urine samples of the rodents. Different detection rates of leptospirosis were observed with MAT (21.2%), PCR (11.3%), and n-PCR (3.3%). The dominant strain was Leptospira serjoehardjo (34.4%, p=0.28), although other serotypes were also found. The prevalence of positive leptospirosis tests in rodents was 15.9, 2.6, and 2.6% among Rattus norvegicus, R. rattus, and Apodemus sylvaticus, respectively.

CONCLUSIONS:

Leptospirosis was prevalent in rodents in Mazandaran Province, northern Iran. MAT was able to detect leptospires more frequently than culture or PCR. The kidney was a more suitable site for identifying leptospiral DNA by n-PCR than urine. Culture was not found to be an appropriate technique for clinical diagnosis.

Characterization of leptospira isolates from animals and humans: phylogenetic analysis identifies the prevalence of intermediate species in India

In this study, 191 culture isolates were recovered from suspected samples of animals and humans in Ellinghausen McCullough Johnson and Harris (EMJH) medium and assessed for its morphological features by dark field microscopy. Extracted DNA from individual culture was subjected to different PCR assays for identification and characterization of leptospira. Out of 99 positive leptospira cultures, 52 pathogenic leptospira isolates were characterized at species level by using partial RNA polymerase β-subunit (rpoB) gene sequences. Phylogenetic analysis of the nucleotide sequences revealed that 30, 8, and 14 isolates belong to L. borgpetersenii / L. interrogans, L. kirschneri, and Leptospira intermediate species, respectively. Based on analysis of 99 leptospira isolates, the prevalent Leptospira species were L. borgpetersenii or L. interrogans (30.30%), L. kirschneri (8%) and Leptospira intermediate species (14.14%) in animals and humans. To the best of authors knowledge, this is the first study to use rpoB gene nucleotide sequence based phylogenetic analysis to identify/detect Leptospira intermediate species (L. wolffii) in animals and humans in India. Hence, the prevalence of this species will surely emphasize the importance of consideration of Leptospira intermediate species and formulate a way for further studies especially in understanding the newly emerging Leptospira in animals and humans and to combat the problem associated with the disease conditions.

Leptospirosis diagnosis: competancy of various laboratory tests

Leptospira can be found in virtually all tropical and temperate areas of the world and is presumed to be the most wide spread zoonoses in the world.Humans contact leptospirosis through mucosal or percutaneous exposure to leptospires in environments contaminated by the urine of chronically infected animal sources. Despite being common, the diagnosis of leptospirosis is often not made unless a patient presents with textbook manifestations of the so called Weil's disease, such as fever plus jaundice, renal failure and pulmonary haemorrhage. Leptospiral infection often has minimal or no clinical manifestations; of the cases in which fever develops, as many as 90% are undifferentiated febrile illnesses. Because of the variety of clinical symptoms seen in the symptomatic cases, leptospirosis at its onset is often misdiagnosed as aseptic meningitis, influenza, hepatic disease or fever (pyrexia) of unknown origin. Moreover, clinicians may fail to recognize that transmission of leptospirosis can occur in the urban setting because it is incorrectly perceived to be a rural disease. Therefore, diagnosis is based on laboratory tests rather than on clinical symptoms alone. In developing countries, laboratory facilities may be inadequate for diagnosis despite a high prevalence of the disease. Of substantial clinical importance, the syndrome of leptospiral pulmonary haemorrhage has emerged in recent years, in diverse places around the world.

Detection and characterization of Leptospira spp. isolated from aborted bovine clinical samples

Leptospira is recognized as an important public health problem worldwide, especially in tropical countries, and is a common cause of abortion in dairy and beef herds. The aim of the present study was to detect and characterize Leptospira as the causative agent of abortion in cattle using a PCR-RFLP in Chaharmahal va Bakhtiari and Isfahan provinces, Iran. A total of 220 bovine aborted foetuses and 120 vaginal discharges from an aborted calf were collected from 64 commercial dairy herds. After isolation of 60 Leptospira spp. from samples, RFLP analysis was carried out with HindIII and HaeIII restriction enzymes in reference strains and isolated for characterization. In a total of 340 specimens, 46 (20.9%) and 14 (11.66%) were identified positive for Leptospira spp. from aborted bovine foetuses and vaginal discharges, respectively. The present results also suggest that L. interrogans serovar hardjo has the highest prevalence in the region under study and L. hardjo is a major pathogen causing bovine abortion in Chaharmahal va Bakhtiari and Isfahan provinces of Iran.

Application and validation of PFGE for serovar identification of Leptospira clinical isolates

Serovar identification of clinical isolates of Leptospira is generally not performed on a routine basis, yet the identity of an infecting serovar is valuable from both epidemiologic and public health standpoints. Only a small number of reference laboratories worldwide have the capability to perform the cross agglutinin absorption test (CAAT), the reference method for serovar identification. Pulsed-field gel electrophoresis (PFGE) is an alternative method to CAAT that facilitates rapid identification of leptospires to the serovar level. We employed PFGE to evaluate 175 isolates obtained from humans and animals submitted to the Centers for Disease Control and Prevention (CDC) between 1993 and 2007. PFGE patterns for each isolate were generated using the NotI restriction enzyme and compared to a reference database consisting of more than 200 reference strains. Of the 175 clinical isolates evaluated, 136 (78%) were identified to the serovar level by the database, and an additional 27 isolates (15%) have been identified as probable new serovars. The remaining isolates yet to be identified are either not represented in the database or require further study to determine whether or not they also represent new serovars. PFGE proved to be a useful tool for serovar identification of clinical isolates of known serovars from different geographic regions and a variety of different hosts and for recognizing potential new serovars.