Histopathological kidney alterations in rats naturally infected with Leptospira / Alteraciones histopatológicas en ratas naturalmente infectadas con Leptospira

Introduction: Histopathological changes by Leptospira in naturally infected rodent reservoirs have been poorly described. Objective: The aim of the current study is to describe renal histopathology associated with leptospirosis infection of naturally infected rodents captured in the urban area of the city of Medellin, Colombia. Materials and methods: We performed hematoxilin-eosin (H-E) on kidney samples collected from 254 captured rodents. The positive samples were processed by Warthin Starry (W-S) staining and PCR- LipL 32. Results: Fifty one rodent kidneys showed H-E histopathological changes that consisted of inflammatory infiltrate with lympho-plasmocitary cells and histiocytes. We performed W-S staining and PCR- LipL 32 to 67 kidney samples, including the 51 that had shown detectable changes by H-E and 16 (8%) of 203 rodents with negative results. Eight of the samples that tested positive for H-E (15.7%) were also positive for W-S staining. All negative for H-E were also negative for W-S staining. Of the W-S positive samples also tested for culture only three tested positive for both. Additionally, 47 (92.1%) samples positive for H-E were positive for PCR; while eleven of the 16 (68.8%) negative for H-E were positive for PCR. The samples positive for PCR were subsequently tested for culture and 11 (23.4%) were positive. Seven samples were positive for PCR and W-S and three were positive for PCR, W-S and culture. All of the PCR- LipL 32 fragments were sequenced and showed specific amplicons for L. interrogans . Conclusions: The Leptospira infection was confirmed in all of the animals tested. The only histological kidney lesion attributable to leptospiral infection in the reservoir was interstitial nephritis.

Introducción. Los hallazgos histopatológicos ocasionados por Leptospira spp. han sido poco estudiados en poblaciones de roedores naturalmente infectados. Objetivo. Describir la histopatología renal asociada con las infecciones naturalmente adquiridas en un grupo de roedores capturados en el área urbana de Medellín, Colombia. Materiales y métodos. Se llevaron a cabo coloraciones de hematoxilina y eosina de los riñones de 254 roedores recolectados en el área de estudio. Las muestras positivas se procesaron con la coloración de Warthin-Starry y mediante reacción en cadena de la polimerasa (PCR)-LipL32. Results. Se observaron cambios histopatológicos con hematoxilina y eosina en 51 riñones de roedores, que consistieron en infiltrado inflamatorio con linfoplasmocitos e histiocitos. Se utilizó coloración de Warthin-Starry y PCR-LipL32 en 67 muestras de riñón que incluyeron las 51 muestras que tuvieron cambios detectables por hematoxilina y eosina y 16 de 203 (8 %) muestras con resultados negativos. Ocho de las muestras positivas por hematoxilina y eosina (15,7 %) también fueron positivas por la coloración de Warthin-Starry. Las muestras negativas por hematoxilina y eosina (8 %) también fueron negativas con la coloración de Warthin-Starry. Tres de las ocho muestras positivas por esta última, también lo fueron por cultivo. Además, 47 (92,1 %) muestras positivas por hematoxilina y eosina fueron positivas por PCR. Del grupo de 16 negativos por hematoxilina y eosina, 11 (68,8 %) fueron positivos por PCR. De las muestras positivas por PCR, 11 también lo fueron por cultivo (23,4 %). Siete muestras fueron positivas por PCR y Warthin-Starry y tres lo fueron por PCR, Warthin-Starry y cultivo. Todos los fragmentos de la PCR-LipL32 fueron secuenciados y mostraron secuencias específicas de L. interrogans . Conclusiones. Se confirmó la infección por Leptospira y la única lesión presente en el reservorio atribuible fue la nefritis intersticial.

Evidencia serológica de circulación de Leptospira spp en Rattus norvegicus naturalmente expuestos en una zona urbana colombiana / Serological evidence of Leptospira spp circulation in naturally-exposed rats (Rattusnorvegicus) in a Colombian urban area

Objetivo Determinar la frecuencia de anticuerpos dirigidos contra especies de Leptospira patógenas en reservorios naturales, con el propósito de establecer evidencia de su papel potencial en la dispersión ambiental de Leptospira y por consiguiente su actuación como agente diseminador de la infección tanto al humano como a otras especies susceptibles. Materiales y métodos El muestreo se llevó a cabo en la Plaza Minorista durante el periodo comprendido entre agosto de 2006 y abril de 2007, en el cual se capturaron 254 roedores Rattus norvegicus. Se obtuvo sangre de estos por punción cardiaca y el suero resultante se procesó con la prueba de Microaglutinación. Resultados El análisis serológico para verificar las serovariedades circulantes de Leptospira spp, dio como resultado que 64 roedores (25,2 por ciento, 95 por ciento CI=19,5-30,1) tuvieron títulos positivos para al menos una de las 11 serovariedades probadas. Conclusiones Los datos muestran que no solo la serovariedad Icterohaemorrhagiae está asociada con esta especie reservoria; también lo están otras serovariedades como Grippothyphosa y Canícola. El estudio permitió determinar la frecuencia de anticuerpos contra especies patógenas de Leptospira para reservorios procedentes de una zona urbana colombiana. Estos datos son relevantes para las entidades de salud pública por constituir la base para la implementación de campañas de control adecuadas para esta zona del país y como modelo de otros estudios similares en otras ciudades colombianas.

Objective Assessing the frequency of antibodies directed against pathogenic Leptospira species found in natural reservoirs for establishing evidence of their potential role in the environmental dispersion of Leptospira and consequent dissemination of the infection to humans as well as to other susceptible species. Material and methods A survey was carried out in the Plaza Minorista from August 2006 to April 2007 in which 254 rats (Rattusnorvegicus) were captured. Blood was obtained from these rodents by cardiac puncture and the resulting serum was used for microagglutination tests. Results Serological analysis for verifying Leptospira spp circulating serovars resulted in 64 rodents (25.2 percent;19.5-30.1 95 percentCI) having positive antibody titres for at least 11 of the serovars tested. Conclusions Frequency data regarding the antibodies so detected showed that the Icterohaemorrhagiae serovar was not the only one possibly associated with this reservoir species, but also with others such as the Grippothyphosa and Canícolaserovars. The study determined the frequency of antibodies against pathogenic Leptospira species for reservoirs from an urban area in Colombia. This data is relevant for public health authorities and might constitute the basis for implementing appropriate control campaigns for this area of the country and, likewise, this work could serve as a model for similar studies in other Colombian cities.

Seroprevalence of Leptospira in Rattus Norvegicus in Grenada, West Indies

OBJETIVE: To determine the seroprevalence of Leptospira and the serovars responsible for Leptospira exposure in rats in Grenada in order to assess rats as a reservoir host for human infection. DESIGN AND METHODS: Rattus norvegicus rodents were collected representing each of the six parishes on the island of Grenada. Serum from 237 rats was tested by the microscopic agglutination test (MAT) and an Immunoglobulin G (IgG) Enzyme-Linked Immunosorbent Assay (ELISA). Seroprevalence rates among parishes were compared using a chi-squared test of homogeneity. RESULTS: Of the 237 serum samples tested, 64 were positive by either MAT or ELISA for an overall seroprevalence of 27%. The ELISA identified 24.5 % (57/233) of the rats positive at a titer of > 1:160. The MAT identified 7.1% (13/183) of the rats positive at a titer of > 1:100. Six of the 13 MAT positive samples had antibodies to multiple serovars. The serovars identified by the MAT with the greatest frequency were from the Icterohaemorrhagiae serogroup. Two rats had antibodies for serogroup Cynopteri, the first time this serogroup has been identified on Grenada. CONCLUSIONS: Our results for Leptospira exposure in rats in Grenada support R. norvegicus as an important reservoir host for Leptospira, particularly those from the Icterohaemorrhagiae serogroup. Because this serogroup is the primary serogroup responsible for documented human exposure in Grenada, exposed rats represent a public health threat.

Microbial pathogens in ticks, rodents and a shrew in northern Gyeonggi-do near the DMZ, Korea

A total of 1,618 ticks [420 individual (adults) and pooled (larvae and nymphs) samples], 369 rodents (Apodemus arius, Rattus norvegicus, Tscherskia triton, Mus musculus, and Myodes regulus), and 34 shrews (Crocidura lasiura) that were collected in northern Gyeonggi-do near the Demilitarized Zone (DMZ) of Korea during 2004-2005, were assayed by PCR for selected zoonotic pathogens. From a total of 420 individual and pooled tick DNA samples, Anaplasma (A.) phagocytophilum (16), A. platys (16), Ehrlichia (E.) chaffeensis (63), Borrelia burgdorferi (16), and Rickettsia spp. (198) were detected using species-specific PCR assays. Out of 403 spleens from rodents and shrews, A. phagocytophilum (20), A. platys (34), E. chaffeensis (127), and Bartonella spp. (24) were detected with species-specific PCR assays. These results suggest that fevers of unknown causes in humans and animals in Korea should be evaluated for infections by these vector-borne microbial pathogens.

Field rats form a major infection source of leptospirosis in and around Madurai, India.

AIMS: To determine the seroprevalence of leptospires and to isolate Leptospira spp. from field rats and bandicoots in and around Madurai. MATERIALS AND METHODS: Thirteen rats and five bandicoots were trapped alive from fields in and around Madurai. Blood samples were tested for anti-leptospiral antibodies by microscopic agglutination test while the urine and kidney samples were used for isolation of leptospires. The isolated leptospires were tested for pathogenic status (13 degrees C test and PCR) followed by serological and genetic characterization. RESULTS: Serology revealed the presence of anti-leptospiral antibodies in 58% (7/12) of field rats and leptospires were isolated from two urine and six kidney samples. The bandicoots were negative in both serology and culture. Analysis of the isolates from field rats revealed that all the isolates were pathogenic except for one, which was further confirmed by serological and genetic characterization. Six of the seven pathogenic isolates were identified as L. interrogans serogroup Autumnalis serovar Akiyami A and one as L. borgpetersenii serogroup Javanica serovar Veldrat Batavia 46. CONCLUSIONS: Serology and isolation reveals that field rats are major natural carriers and shedders of leptospires in and around Madurai.

Quick control of bubonic plague outbreak in Uttar Kashi, India.

A localized outbreak of bubonic plague occurred in village Dangud (population 332), district Uttar Kashi, Uttaranchal, India in the second week of October 2004. 8 cases were considered outbreak associated based on their clinical and epidemiological characteristics; 3 (27.3%) of them died within 48 hours of developing illness. All the 3 fatal cases and five surviving cases had enlargement of inguinal lymph nodes. None of them had pneumonia. The age of the cases ranged from 23-70 years and both sexes were affected. No such illness was reported from adjoining villages. The outbreak was fully contained within two weeks of its onset by supervised comprehensive chemoprophylaxis using tetracycline. A total of approximately 1250 persons were given chemoprophylaxis in three villages. There was no clear history of rat fall in the village. No flea was found on rodents or animals. 16 animal serum samples were found to be negative for antibodies against F-1 antigen of Y. pestis. However, Y. pestis was isolated from two rodents (Rattus rattus and Mus musculus) trapped in the village. One case and three animal sera showed borderline sero-positivity against rickettsial infection. The diagnosis of plague was confirmed by detection of four fold rise of antibody titre against F-1 antigen of Yersinia pestis in paired sera of three cases (one of the WHO approved criteria of diagnosis of confirmed plague). This outbreak and the occurrence of earlier outbreaks of plague in Surat (Gujarat) and Beed (Maharashtra) in 1994 and in district Shimla (Himachal Pradesh) in 2002 confirm that plague infection continue to exist in sylvatic foci in many parts of India which is transmitted to humans occasionally. Thus, there is a strong need for the States to monitor the plague activity in known sylvatic foci regularly and have a system of surveillance to facilitate prompt diagnosis and treatment of cases to control the disease. This investigation highlights that with high index of suspicion the disease can be diagnosed early and mounting of supervised comprehensive response can prevent the disease to proceed to pneumonic stage where man to man transmission gets established and outbreak assumes larger dimensions.

Surveillance of leptospiral carriage by feral rats in Barbados

Rodents, particularly rats, are widely held to be the source of most human cases of leptospirosis. Feral rats were trapped at sites throughout Barbados during two six month surveys: from October to March 1986/87 and from October to March 1994/95. During the first survey, 63 rats were trapped, of which 26 (41) were identified as Rattus rattus and 37 (59) as Rattus norvegicus. In the second study, 100 rats were trapped, of which R. rattus comprised 24(24) and R. norvegicus 76(76). Cultures of blood, urine and kidney were made in EMJH medium. Leptospires were isolated from 12/63 (19) and from 16/100 (16) of the rats during 1986/87 and 1994/95, respectively; 27/28 isolates were recovered from the kidneys or urine or both, while only one isolate was recovered from the blood. During the first study, isolates were identified as serovars copenhageni (11) and arborea (1), while in the second study, serovars copenhageni (9), arborea (5) and bim (1) were identified; one isolate was lost before it could be identified. In the first study, antibodies were detected by microscopic agglutination at a titre of > or = 100 in 26/62 (42) of rats tested, while in the second survey, 5/100 (5) of rats had similar titres. In two surveys, conducted eight years apart, we confirmed that rats in Barbados are commonly infected with leptospires, and that viable organisms are found in the kidneys and urine, evidence of chronic infection and thus excretion of leptospires in rodent urine. Moreover, the predominant serovar isolated was copenhageni, of which Rattus spp. are the worldwide reservoir. There was little evidence that rats act as a reservoir for the serovar bim, the most common cause of human leptospirosis in Barbados.

Leptospirosis in the Philippines.

Leptospirosis was first isolated in the Philippines from one of the human cases of Weil's Disease in 1932 and from then up to 1970 a total of 65 cases were studied sporadically. From 1971 up to 1973 a total of 390 cases were studied out of which 82 (21.02%) were found positive by isolation and serological examination. An outbreak of leptospirosis was followed up from 1976 to 1983 in a penal farm in Sablayan, Mindoro. At the time of the outbreak, 31% of the sera from patients and those with complaints reacted to one or more antigen pools with 40% of these reactors reacting to only one antigen pool. Only one percent of prisoners and residents without complaints reacted to one or more antigen pools, with 80% of these reactors reacting to pool 3 alone. Three and half years later, a first follow-up was done in which 9.07% reacted to one or more pools. Of these, 42% reacted to pool 2 and 82% to pool 3 alone or in combination with other pool. Ninety five percent of those reacting to Pool 2 reacted to L. pyrogenes and 88% of those that reacted to Pool 3 reacted to L. autumnalis. More than three years later after the first follow-up, a second follow up was done. This time 2.29% reacted to one or more pools. Most reacted specifically to L. autumnalis. The residents outside the penal farm were all non-reactive. Sampling from another penal colony and in four agricultural areas revealed no significant reactivity.(ABSTRACT TRUNCATED AT 250 WORDS)

Numbers of Leptotrombidium (Leptotrombidium) deliense (Acarina: trombiculidae) and prevalence of Rickettsia tsutsugamushi in adjacent habitats of peninsular Malaysia.

Numbers of L. (L.) deliense larvae were determined in adjacent habitats over a 16 month period. Both R. argentiventer and R. tiomanicus were highly efficient hosts for L. (L.) deliense. R. argentiventer was host to significantly greater numbers of chiggers per rat than was R. tiomanicus. The 2 habitats were similar in numbers of chiggers collected. No consistent correlation was apparent between numbers of chiggers and any single weather factor, but the chigger population seemed to be adversely affected by a 2 month period during which total evaporation greatly exceeded total rainfall. Direct fluorescent antibody examination of tissues from unfed L. (L.) deliense showed that 2 of 420 larvae (0.5%) contained organisms morphologically resembling R. tsutsugamushi. Considering the vector load and numbers of chiggers being returned to the ground by a given host, a rate of 0.5% appeared adequate to account for the prevalence rate of R. tsutsugamushi observed in the 2 host species.