Serogroup Australis Research Articles

Leptospirosis: An ignored cause of acute renal failure in Taiwan

Leptospirosis, caused by a spirochete, is the most common zoonosis in domestic or wild animals. Animals excrete infected urine in soil or water and may cause human infections through abrased wound, mucosa, conjunctiva, or by swallowing contaminated water. Clinical presentations of leptospirosis are mostly subclinical. Five to ten percent of leptospirosis are fatal, causing fever, hemorrhage, jaundice, and acute renal failure (Weil's syndrome). Leptospirosis has been ignored as a cause of acute renal failure in Taiwan. We report two patients with leptospirosis who presented with high fever, abdominal pain, jaundice, and acute renal failure. Patient 1 died on day 12 of admission of multiple organ failure associated with pancytopenia, hypogammaglobulinemia, and reactive hemophagocytosis. Leptospirosis was recognized after death. Patient 2 was admitted with similar presentations 2 weeks later. Penicillin and doxycycline were given early in the course, and azotemia, jaundice, respiratory failure, and aseptic meningitis gradually improved. Renal biopsy showed interstitial nephritis. Several tubular clearance tests showed proximal tubular defect with severe bicarbonate wasting (FeHCO 3 − 20.9%) and incomplete type II renal tubular acidosis without affecting the distal nephron. After 80 days of treatment, this patient was discharged with recovery of conscious level and renal function. This is the first leptospirosis patient who detailed tubular functional and morphological studies of the kidney. Diagnosis of leptospirosis was made by microscopic agglutination test (MAT) for antibody to leptospira and by polymerase chain reaction (PCR) for leptospira DNA in blood and urine ( interrogans serogroup australis in case 1 and Leptospira borgpetersenii serogroup ballum in case 2). Because active surveillance has resulted in 13 cases diagnosed as leptospirosis islandwide thereafter, underestimation and ignorance of leptospirosis as a cause of acute renal failure may occur in Taiwan. Therefore, an area with a low leptospirosis incidence may actually have a very high incidence. Leptospirosis should be suspected in febrile patients with jaundice and renal failure when pathogens cannot be identified by traditional culture for microorganisms.

Chronic hepatitis associated with Leptospiral infection in vaccinated beagles

Sixteen juvenile Beagle dogs originating from a single breeding colony and regularly vaccinated against Leptospira interrogans (serogroups Canicola and Icterohaemorrhagiae) developed a clinical syndrome characterized by retarded growth, weight loss and often ascites. Over a 10-month period, post-mortem examinations were performed on all affected dogs. Gross lesions were confined to the liver which was often firm, tan-coloured and mottled. Microscopically, hepatic lesions ranged from those of severe chronic hepatitis to mild diffuse hepatocellular vacuolation, with bile stasis, occasional scattered lymphocytic aggregates and haemosiderin granulomas. Special stains and electron microscopy revealed spirochaetes within bile canaliculi. The genus Leptospira was recognized by immunohistochemical methods in nine dogs. Leptospires were isolated from six dogs, but serological tests failed to detect significant titres of antibody to L. interrogans in these animals. A serological survey of 37 kennelmates demonstrated that 20 dogs had high titres of serogroup Australis leptospiral antibody, which could not have resulted from vaccination. These findings strongly suggest a connection between the presence of leptospires and the hepatic lesions.

Seroepidemiology of canine leptospirosis on the island of Barbados

Previous surveillance in Barbados documented the absence of infection with Leptospira serogroup Canicola in dogs. The aim of this study was to survey the current state of canine leptospirosis in Barbados, 10 years after the last survey. Sera from 78 unwanted dogs scheduled for euthanasia and 61 dogs suspected of having acute leptospirosis were tested by microscopic agglutination (MAT) and by an ELISA method adapted for canine IgM and IgG antibodies. The seroprevalence in unwanted dogs was 62% ( 48 78 ), at an MAT titre of ≥ 100. The majority of animals had low titres, suggestive of previous infection. Serogroup Autumnalis was the most common reactor (45%), followed by serogroups Icterohaemorrhagiae and Australis (each 16%) and Pomona (13%). Serogroup Ballum was uncommon in this group. The seroprevalence determined by MAT in acutely-ill dogs was 75% ( 46 61 ). The most common predominant serogroup was Icterohaemorrhagiae (36%) followed by serogroup Australis (13%), while serogroups Autumnalis and Ballum were also of little significance. Paired specimens were available from eight acutely-ill dogs. One animal was seronegative while five dogs showed evidence of seroconversion. An IgM-ELISA titre of ≥ 320 was used to confirm current infection in eight of these nine animals. Previous studies in Barbados showed a higher prevalence of serogroup Icterohaemorrhagiae than of Autumnalis, but the relative frequency of these two serogroups may be changing. The high seroprevalence in dogs is of public health concern because the close contact between dogs and man may provide the link between a reservoir in the environment and susceptible humans.

Leptospirosis in Kolenchery, Kerala, India: epidemiology, prevalent local serogroups and serovars and a new serovar.

Leptospirosis is the most widespread zoonosis in the world. It is mostly an occupational disease especially in rural areas. Kolenchery is in the midlands of Kerala. The landscape consists of marshy land and dry land interspersed by rivulets and ponds. Irrigation of dry lands for cultivation during the summer months started in mid 1980s after the irrigation projects were commissioned. Cases of leptospirosis were rarely diagnosed in Kolenchery before 1987. Since then a yearly increase in incidence is observed. No major study on either epidemiology or clinical picture has been done on human leptospirosis in Kerala so far. The aim of this study was to define the major clinical presentations, epidemiology of the infection and demonstrate the predominant serogroups and serovars causing the illness in this limited geographical area. The study involves 976 cases of leptospirosis confirmed by culture and/or serological tests. Serogroups Autumnalis, Australis and Icterohaemorrhagiae were the commonest. Mortality rate was 5.32%. The increase in incidence is probably due to the geographical characteristics, continuous moisture of the soil due to irrigation in summer and year-round cultivation making food and cover available to host rodents. Close interaction of humans, animals, soil and water in this region make the spread of leptospirosis to humans easy. Confirmation of cases has been done by enzyme linked immunosorbent assay (ELISA) and/or microscopic agglutination test (MAT) and/or by culture. Serovar identification has been done in 21 cultures isolated from patients. One new serovar belonging to serogroup Australis has been identified from a patient and named serovar Australis bharathy.

Prospective serological study of leptospirosis in southern Spain.

This article reports data concerning a serosurvey carried out in Southern Spain to assess the current epidemiological status of a population exposed to risk of leptospirosis. Microagglutination and IgM-EIA tests were carried out on sera from a sample of workers in agriculture-related occupations, exposed to marsh waters. A cohort of 197 workers were followed for a year in an active surveillance program to evaluate seroconversion (laboratory confirmed leptospirosis). The results have shown for the cohort a density of incidence: 6.4 x 100 persons per year, and for the reference population an accumulated incidence of 41.25/100,000. Prevalence rates (P) were 21.3 x 100 and 144 x 10(5) for the cohort and population respectively. Rates were higher in cray-fishers (P: 62.7%), rice-workers, and butchers. This is the first report identifying cray-fishers as a high risk group for leptospirosis, and the reporting of human contamination by Australis serogroup in Spain.

Survey on the prevalence of leptospira infections in the Italian population.

This investigation is the first nationwide survey on the circulation of leptospira infections in human beings in Italy. In nine out of twenty Italian regions, representative samples of the population were investigated for the presence of leptospira infections. Unexpectedly, leptospira infections were found to be widespread, the number of cases being much higher than the diagnosed clinical cases. There were found to be high, medium, and low risk areas. On the whole, the risk for the rural population was no higher than the risk for urban dwellers; leisure activities, contact with animals and residence on the plain versus residence in the hills were important risk factors. There was an unidentified risk factor in urbanites which was absent in the rural population. A changing pattern in infecting serovars was observed, with infections from serogroups Sejroe, Javanica and Australis prevailing over infections from the Icterohaemorrhagiae and Bataviae serogroups, which were the main agents of human leptospirosis during the 1950s. The mechanisms of these changes, the need for epidemiological surveys and improved diagnostic methods of screening are discussed.

Evaluation of an immunoenzymatic test (ELISA) for the diagnosis of leptospirosis in Italy.

An enzyme-linked immunosorbent assay (ELISA) was assessed to detect in humans IgM and IgG against the main serogroups/serovars of Leptospira present in Italy. Sonicated antigens from strain Wijnberg, serogroups Icterohaemorrhagiae and Riccio 2, serogroup Australis, were used in ELISA and the results were compared to microagglutination test (MAT). IgM were confirmed to be the predominant class of antibodies; the total sensitivity obtained by Wijnberg/ELISA with the sera of patients infected by different serogroups was 81.5% in relation to MAT, better sensitivity was achieved by the use of Riccio 2/ELISA; no reaction occurred with the control sera. Cross-reactivity was noted with some sera of patients with Lyme disease (IgM) and with few sera of patients with autoimmune disease (IgM and IgG). To improve the sensitivity of the ELISA both antigens Wijnberg and Riccio 2 must be employed in the immunoenzymatic assay, since serogroup Australis must be considered as a new emerging serogroup causing human leptospirosis in our country.

Pulsed-field gel electrophoresis of NotI digests of leptospiral DNA: a new rapid method of serovar identification.

Fingerprints for 72 reference serovar strains of pathogenic Leptospira spp. were obtained by pulsed-field gel electrophoresis (PFGE) following NotI restriction digests of the chromosome. These strains included the serovar reference strains of serogroups Australis, Ballum, Bataviae, Grippotyphosa, Panama, Pomona, and Pyrogenes. Sixty-four serovars could be identified by a unique NotI restriction profile. The remaining serovars were differentiated by chromosomal digestion with SgrAI. These included four serovars from serogroup Australis, two serovars from serogroup Ballum, and two serovars from serogroup Bataviae. Thirteen of 18 recent clinical isolates identified by microagglutination test and cross-adsorption procedure were correctly typed by PFGE. The results indicate that PFGE, which is considerably more rapid than serology, should be useful for identification and epidemiological studies.

Immunodominant antigens recognized by the human immune response to infection by organisms of the species Leptospira interrogans serogroup Australis.

Serum samples from patients infected by organisms of Leptospira interrogans serogroup Australis were tested by Western blot to determine the nature of major antigens that are involved in the immune response. Although there was some patient-to-patient variability, immunodominant genus-specific antigens were found to be proteins of apparent molecular ratio 68, 46 and 35-kDa, and lipopolysaccharide (LPS) sub-units in the 35-14-kDa region. Serogroup epitopes specific for Australis were exclusively saccharides of about 32 and 24 kDa: a serovar-specific antigen for serovar lora was of 38-40 kDa and behaved like a protein. Antibodies to the LPS serogroup-specific antigens and to the 38-40 kDa protein were long-lasting and consequently suggest that these immunodominant epitopes are important in resistance to re-infection.

Immunodominant antigens recognized by the human immune response to infection by organisms of the species Leptospira interrogans serogroup Australis

Immunodominant antigens recognized by the human immune response to infection by organisms of the species Leptospira interrogans serogroup Australis

Muskrats as carriers of pathogenic leptospires in The Netherlands.

Leptospires were isolated from 24 of 327 (7%) muskrats (Ondatra zibethicus) caught in The Netherlands. All isolates were identified as Leptospira interrogans. One isolate was typed as serovar copenhageni in the Icterohaemorrhagiae serogroup, one as serovar lora in the Australis serogroup. Twenty-one isolates showed a close relationship with serovars grippotyphosa, valbuzzi, muelleri and ratnapura from the Grippotyphosa serogroup. One isolate was lost. Sera from 196 muskrats were examined by the microscopic agglutination test. Forty-five (23%) sera reacted positively (titers greater than or equal to 1:160), 42 (21%) of these 45 sera to Grippotyphosa and 3 (2%) to Sejroe serogroup antigens. This is the first report of serological and cultural evidence of leptospira infection in muskrats in The Netherlands.

Leptospires Isolated from Toads and Frogs on the Island of Barbados

Four pathogenic strains of leptospires were isolated from the kidneys of toads (Bufo marinus) and seven from frogs (Eleutherodactylus johnstonei). Isolates from two toads and one frog belonged to serovar bim, the causative agent of most cases of severe leptospirosis on Barbados. The other eight strains belonged to a new serovar within the Australis serogroup. The name bajan is proposed for this new serovar of Leptospira interrogans.

Restriction endonuclease analysis as a taxonomic tool in the study of pig isolates belonging to the Australis serogroup of Leptospira interrogans.

Restriction endonuclease analysis was performed on DNAs from the type strains of the Australis serogroup of Leptospira interrogans by using 20 restriction enzymes, and the electrophoretic patterns obtained were compared with patterns obtained from 162 Australis serogroup isolates from pigs. It proved to be a quick and reliable method for typing such strains. All of the pig isolates were identified as either serovar bratislava or muenchen. It also showed differences at the subserovar level which may be important in (i) understanding the epidemiology of the Australis serogroup, (ii) the development of suitable vaccines, and (iii) pathogenesis and pathogenicity studies. Two genotypes (B2b and M2) accounted for 92% of isolates from aborted or stillborn piglets, while a third genotype (B2a) was the only one recovered from the brains of piglets with meningitis.

First human isolate of Leptospira interrogans as serovar bratislava in Italy.

A strain of Leptospira interrogans was isolated from a patient suffering from leptospirosis and was typed by the Cross Agglutination Absorption test using monoclonal antibodies prepared against different serovars of the Australis serogroup. This newly isolated strain belonged to serovar bratislava. It is the first reported isolation from man, in Italy, of Leptospira bratislava, thus supporting the emerging role of this serovar in human leptospirosis.

Clinical Leptospira interrogans serogroup Australis serovar lora infection in a stud farm in The Netherlands.

A Leptospira interrogans serogroup australis serovar lora infection in a stud farm is reported. During three successive years (1984-1986) clinical leptospirosis with a severe often rapid, fatal course was seen in 12 foals. Clinical examination revealed severe respiratory distress, depression and pyrexia. Other symptoms were diarrhea (2), jaundice (1), and an unsteady gait (1). Morphological characteristics of the disease were massive pulmonary haemorrhage and haemorrhagic-thrombotic or extracapillary glomerulonephritis with tubulonephrosis and interstitial oedema. In most foals high or increasing MAT titres to serovar bratislava were found; from one foal Leptospira interrogans serovar lora was isolated. Serological examination of all 56 mares at the farm (August 1986) revealed antibodies to serovar bratislava in 64 per cent of the animals. These findings support the idea that Leptospira interrogans serovar bratislava and closely related strains (in this study serovar lora) may be adapted to and maintained by the horse population.

Prevalence of leptospirosis in Belize

In a search for leptospirosis in Belize, at least one current case was diagnosed among 11 febrile hospital patients examined in a 2-week period in mid-1984. Sera from 440 survey subjects in 6 schools, 4 urban communities and 9 rural communities were examined for leptospiral antibodies by the microscopic agglutination test. 20 of 174 (11·5%) school pupils, 19 of 88 (22%) urban community subjects and 66 178 (37%) rural community subjects were positive at titres ⩾1:50, and 7·5%, 17% and 26%, respectively, were positive at ⩾1:100. Among all groups of survey subjects, serological reactions to antigens in the Australis serogroup predominated. Up to 81% of 155 sera from cattle in various areas of Belize were positive at titres ⩾1:100. Serological reactions to serogroup Sejroe predominated (43%), followed by Pyrogenes (16%) and Australis (15%). 20 of 71 (28%) pig sera were positive at ⩾1:100, predominantly to serovars in the Australis serogroup (51%). Of 162 sheep or goat sera examined, 65 (40%) were positive at ⩾1:100, mainly to serogroup Autumnalis (25%), followed by Australis (15%).

Leptospires in the marine toad (Bufo marinus) on Barbados.

Leptospires were isolated from the kidneys of four of 211 toads (Bufo marinus) caught on Barbados. Two of the isolates were identified as Leptospira interrogans serovar bim in the Autumnalis serogroup (the most common cause of leptospiral illness on Barbados), and two as possibly new serovars in the Australis serogroup. Sera from 198 of the toads were examined by the leptospire microscopic agglutination test. Forty-two (21%) were positive at titers of greater than or equal to 1:100, and 54 (27%) at greater than or equal to 1:50. The predominating serogroups were Australis (50%), Autumnalis (23%) and Panama (13%). The agglutination tests on the culture-positive toads showed that serologic studies alone may be of limited value in these animals. Bufo marinus can harbor pathogenic leptospires, and it may be a significant source of the Autumnalis serogroup infections in the Caribbean.

A waterborne outbreak of leptospirosis.

During the period from July 10-26, 1984, 33 cases of serologically confirmed leptospirosis occurred in a small town in central Italy. The fatality rate, including the deaths of two unconfirmed cases, was 8.6% (3 of 35). Based on serologic evidence, the infection was caused by leptospires of the serogroup Australis. Epidemiologic study showed that the patients contracted the infection by drinking water from a fountain. The source of leptospiral contamination was probably a hedgehog trapped in a reservoir of water not in use but still connected to the water system of the fountain.

Boars as carriers of leptospires of the Australis serogroup on farms with an abortion problem.

Boars as carriers of leptospires of the Australis serogroup on farms with an abortion problem.

Isolation of leptospires from the genital tract and kidneys of aborted sows.

Twenty sows were examined as part of an investigation into the relative importance of the genital and urinary tracts as sites of leptospiral persistence in pigs. The sows had previously either aborted leptospire-infected fetuses or aborted on farms where leptospire infection had been demonstrated in other litters. Leptospires belonging to the Australis serogroup were recovered from the upper genital tract of all the sows. In contrast, leptospires were only recovered from 75 per cent of their kidneys. Isolates from 10 of the sows were identified to serovar level: six were serovar muenchen and four were bratislava. Persistence was observed in renal and genital tissues for up to 147 days after abortion.