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Within the past few decades, improvement in sanitation and economic growth has driven a changing epidemiology of hepatitis A in the Western Pacific Region (WPR) of the World Health Organization (WHO). In this review, we gathered available published information on hepatitis A epidemiology of the countries in the WPR and reviewed the trends reported in the literature from the years 2000 to 2021. Many countries have shifted from high endemicity to low endemicity. Moreover, the administration of the hepatitis A vaccine among children in recent years has shifted disease susceptibility to the older population. Seroprevalence among children has decreased in most countries, while nearly 100% seropositivity is seen in mid adulthood. This is contrary to the epidemiology seen in previous decades when most children achieved immunity by age ten. This also presents a paradox in that better living conditions have caused more vulnerability to the older age groups who are at higher risk for severe disease. Given these trends, we recommend vaccination of vulnerable populations such as the older age groups and inclusion of the hepatitis A vaccine in government immunization programs.
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Leptospira enters humans and animals through injured skin or mucous membranes by direct or indirect contact with urine excreted from infected reservoirs. Individuals with cut or scratched skin are at high risk of infection and are recommended to be protected from contact with Leptospira, but the risk of infection via skin without apparent wounds is unknown. We hypothesized that the stratum corneum of the epidermis might prevent percutaneous invasion of leptospires. We established a stratum corneum deficient model of hamsters using the tape stripping method. The mortality rate of hamsters lacking stratum corneum that were exposed to Leptospira was higher than that of controls with shaved skin, and was not significantly different from an epidermal wound group. These results indicated that the stratum corneum plays a critical role in protecting the host against leptospiral entry. We also examined the migration of leptospires through the monolayer of HaCaT cells (human keratinocyte cell line) using Transwell. The number of pathogenic leptospires penetrating the HaCaT cell monolayers was higher than that of non-pathogenic leptospires. Furthermore, scanning and transmission electron microscopic observations revealed that the bacteria penetrated the cell monolayers through both intracellular and intercellular routes. This suggested that pathogenic Leptospira can migrate easily through keratinocyte layers and is associated with virulence. Our study further highlights the importance of the stratum corneum as a critical barrier against the invasion of Leptospira found in contaminated soil and water. Hence, preventative measures against contact infection should be taken, even without visible skin wounds.
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Leptospira interrogans , Leptospira , Leptospirosis , Cricetinae , Animales , Humanos , Leptospirosis/microbiología , Epidermis/patología , Piel/patologíaRESUMEN
Leptospirosis is a zoonotic disease caused by infection with pathogenic leptospires. Consistent with recent studies by other groups, leptospires were isolated from 89 out of 110 (80.9%) soil or water samples from varied locations in the Philippines in our surveillance study, indicating that leptospires might have a life cycle that does not involve animal hosts. However, despite previous work, it has not been confirmed whether leptospires multiply in the soil environment under various experimental conditions. Given the fact that the case number of leptospirosis is increased after flood, we hypothesized that waterlogged soil, which mimics the postflooding environment, could be a suitable condition for growing leptospires. To verify this hypothesis, pathogenic and saprophytic leptospires were seeded in the bottles containing 2.5 times as much water as soil, and bacterial counts in the bottles were measured over time. Pathogenic and saprophytic leptospires were found to increase their number in waterlogged soil but not in water or soil alone. In addition, leptospires were reisolated from soil in closed tubes for as long as 379 days. These results indicate that leptospires are in a resting state in the soil and are able to proliferate with increased water content in the environment. This notion is strongly supported by observations that the case number of leptospirosis is significantly higher in rainy seasons and increased after flood. Therefore, we reached the following conclusion: environmental soil is a potential reservoir of leptospires. IMPORTANCE Since research on Leptospira has focused on pathogenic leptospires, which are supposed to multiply only in animal hosts, the life cycle of saprophytic leptospires has long been a mystery. This study demonstrates that both pathogenic and saprophytic leptospires multiply in the waterlogged soil, which mimics the postflooding environment. The present results potentially explain why leptospirosis frequently occurs after floods. Therefore, environmental soil is a potential reservoir of leptospires and leptospirosis is considered an environment-borne as well as a zoonotic disease. This is a significant report to reveal that leptospires multiply under environmental conditions, and this finding leads us to reconsider the ecology of leptospires.
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Leptospira , Leptospirosis , Animales , Leptospirosis/epidemiología , Leptospirosis/veterinaria , Suelo , Agua , Zoonosis/epidemiología , Zoonosis/microbiologíaRESUMEN
Emergence of drug resistance demands new therapeutic strategies against the human immunodeficiency virus (HIV). Currently, there is an increasing research focus on targeting gene expression-the crucial step wherein new viruses and new viral strains are amplified. Moreover, natural products are also being considered as potential candidates for new antivirals. We screened the extract obtained from a Philippine medicinal plant, Mentha cordifolia (Mc). In this study, we demonstrated that Mc ammonium sulfate extract has antiretroviral activity against HIV. HIV-1 latently infected cells (OM10.1) were pretreated with Mc extract and activated with TNFα. In treated cells, viral replication was inhibited in both cell culture supernatant and whole cell lysates. The level of viral production, as measured by the viral p24 protein concentration, was very much inhibited under noncytotoxic concentrations to the similar level without addition of TNFα. Luciferase assays, however, showed that Mc does not inhibit the HIV-1 long terminal repeat-driven gene expression. IκBα degradation and p65 nuclear translocation was also not affected as visualized through Western blot and immunofluorescence. These observations demonstrated that Mc possessed an antiviral component against HIV-1 and warrant further work to explore its target of action at a later step of gene expression. Our study introduces a potential source of a lead compound that targets steps in the HIV life cycle.
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Infecciones por VIH , VIH-1 , Mentha , Antivirales/farmacología , Línea Celular , Humanos , Extractos Vegetales/farmacología , Replicación ViralRESUMEN
Water buffalo is an indispensable livestock in the Philippines. Leptospirosis is a serious zoonosis that can be fatal to humans and cause reproductive problems in livestock. Leptospirosis has been reported in some countries where water buffaloes are commercially raised, highlighting the Leptospira prevalence in this farming system, but information on leptospirosis in water buffalo farms in the Philippines is limited. In this study, we collected blood samples from rats (n = 21), and water buffaloes (n = 170) from different groups and locations in one intensive-type buffalo farm in the Philippines. Serum was analyzed by microscopic agglutination test (MAT). Anti-Leptospira antibodies reacting with serogroups Canicola, Icterohaemorrhagiae and Pomona were found in sera of 30% tested rats, and 48% of water buffalo sera tested positive for at least one Leptospira strain, in which serogroups Mini, Hebdomadis, Tarassovi and Pyrogenes were predominantly agglutinated. The number of seropositive young water buffaloes (< 1 year-old) was lower than that of older seropositive ones. Furthermore, sera from younger water buffaloes were reactive with single serotypes with low MAT titers, but older animals were reactive with multiple Leptospira strains with variable MAT titers. In addition, antibodies against serogroups Icterohaemorrhagiae and Pomona were detected in both animals. Finally, Leptospira infection was found associated with age and animal grouping, highlighting the impact of management in the persistence of leptospirosis at intensive-type buffalo farm settings in the Philippines. Further investigation and appropriate control strategies are required to prevent leptospirosis from causing risks to public health and economic losses to the water buffalo farming industry.
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Crianza de Animales Domésticos , Búfalos , Leptospira/clasificación , Leptospirosis/veterinaria , Animales , Femenino , Leptospirosis/epidemiología , Leptospirosis/microbiología , Masculino , Filipinas/epidemiología , Prevalencia , Ratas , Estudios SeroepidemiológicosRESUMEN
Early diagnosis based on laboratory confirmation is essential for managing leptospirosis. This study investigated the effectiveness of a novel method of detecting leptospirosis that combines measurement of anti-Leptospira antibodies by the microscopic agglutination test (MAT), enzyme-linked immunosorbent assay (ELISA), and immunochromatographic test (ICT) and leptospiral DNA by loop-mediated isothermal amplification (LAMP) and real-time PCR in plasma and 2 types of urine pellets. Of 113 suspected cases, 68.1%, 76.1%, and 60.2% were positive by MAT, ELISA, and ICT, respectively. Real-time PCR using DNA purified from urine pellets collected by low-speed centrifugation yielded positive signals for patients in late acute as well as early phase who were positive by LAMP using plasma DNA or urine pellets. Among antibody-negative patients, 9.5% were positive by DNA detection. These findings indicate that the leptospirosis detection rate is increased by combining antibody and DNA detection, providing a new tool for timely diagnosis of infection.
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Anticuerpos Antibacterianos/sangre , ADN Bacteriano/sangre , ADN Bacteriano/orina , Pruebas Diagnósticas de Rutina/métodos , Desastres , Leptospira/aislamiento & purificación , Leptospirosis/diagnóstico , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Diagnóstico Precoz , Femenino , Humanos , Inmunoensayo/métodos , Masculino , Persona de Mediana Edad , Técnicas de Amplificación de Ácido Nucleico/métodos , Sensibilidad y Especificidad , Adulto JovenRESUMEN
OBJECTIVE: This study assessed the knowledge, attitudes and practices of the community residents on the prevention and control of Leptospirosis in the National Capital Region, Philippines.METHODS: In this cross-sectional study, four-stage random cluster sampling proportional to size was used to select the 413 respondents from 30 villages in the National Capital Region. The mother or any responsible adult served as the respondent for the community survey which yielded data on the knowledge, attitudes, domestic practices, and sources of information for the prevention and control of Leptospirosis. Encoding was done using Epi Info Version 6. Descriptive statistics was generated through Microsoft Excel.RESULTS: Majority of the respondents were able to correctly identify that the causative agent of leptospirosis is bacteria (91%), that the disease is transmitted by the urine of infected of rats (89%) through skin abrasions (71%) and mucous membranes (57%). Most commonly identified signs and symptoms of the disease include acute febrile illness with myalgia (87%), difficulty of breathing and decreased urine output (72%). Majority identified the prevention and control measures correctly. Wearing of boots, maintaining a clean and orderly house and maintaining good sanitation were the top answers of the respondents. In terms of attitudes, respondents had positive attitudes towards the preventive practices of wearing boots or following health advisories of authorities (99%). Majority also believed that leptospirosis is curable if detected early (99%) and that it is a serious disease (98%). Similarly, more than 90% had positive attitude when it comes to health care. Wading in flood waters (93%), walking barefoot (85%) and conducting clearing activities after flood (63%) were the commonly believed forms of exposure to the disease. In terms of domestic practices, respondents usually clean their surroundings (40%), avoid wading in floodwaters (25%), wear boots (21%) to protect themselves from acquiring leptospirosis. Primary sources of information on leptospirosis were the mass media (46%), health workers (17%) and the health facilities (14%). The most common educational materials read by the respondents were flyers (9%), posters (8%), and leaflets (7%).CONCLUSION: In general, majority of the respondents were knowledgeable on the causes, signs and symptoms, and modes of transmission of leptospirosis, and had favorable attitudes towards the prevention and control measures against leptospirosis. However, when it comes to domestic practices, less than 40% actually implement measures for the prevention and control of leptospirosis. Respondents' main source of information was the mass media and very few have read educational materials containing information about the prevention and control of leptospirosis.
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Humanos , Masculino , Femenino , Ratas , Animales , Bacterias , Roedores , Ictericia , Leptospirosis , Anomalías Múltiples , Estudios Transversales , Inundaciones , Instituciones de Salud , Personal de Salud , Deformidades Congénitas de las Extremidades , Membrana Mucosa , Mialgia , Filipinas , Saneamiento , Encuestas y Cuestionarios , Actitud , OrinaRESUMEN
Leptospirosis is a worldwide zoonosis. The importance of urban leptospirosis is recognized in Japan: urban rats carry pathogenic leptospires and people acquire these pathogens through contact with surface water or soil contaminated by the urine of the infected animals. To determine the current Leptospira carriage rate in urban rats, 29 wild rats were trapped in the central area of Fukuoka and strains isolated from their kidneys and urine analyzed. When semi-solid Korthof's medium containing 0.1% agar was used for isolation, 72.2% and 30.8% of the kidney and urine cultures, respectively, were found to be Leptospira-positive. The isolates belonged to Leptospira interrogans, and were classified into two groups (serogroups Pomona and Icterohaemorrhagiae) based on the results of gyrB sequence analysis and microscopic agglutination testing (MAT). Strains belonging to serogroup Icterohemorrhagiae grew well in liquid medium. On the other hand, serogroup Pomona isolates multiplied very little in liquid medium, but did grow in a semi-solid medium. Although strains belonging to serogroup Pomona have not been recognized as native to Japan, this strain may be widely distributed in urban rats. Representative strains from each group were found to be highly pathogenic to hamsters. Our findings should serve as a warning that it is still possible to become infected with leptospires from wild rats living in inner cities of Japan. Furthermore, the use of semi-solid medium for culture will improve the isolation rate of leptospires from the kidneys of wild rats.
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Técnicas Bacteriológicas/métodos , Medios de Cultivo/química , Leptospira interrogans/aislamiento & purificación , Leptospirosis/veterinaria , Enfermedades de los Roedores/diagnóstico , Enfermedades de los Roedores/microbiología , Pruebas de Aglutinación , Animales , Ciudades , Girasa de ADN/genética , Modelos Animales de Enfermedad , Japón , Riñón/microbiología , Leptospira interrogans/patogenicidad , Leptospirosis/diagnóstico , Leptospirosis/microbiología , Mesocricetus , Ratas , Orina , VirulenciaRESUMEN
Leptospirosis is highly endemic in the Philippines and a serious concern to public health. Local research on candidate vaccine is moving through the development pipeline. The availability of vaccines alone does not guarantee acceptance because individuals' vaccination choice decision is influenced by several factors. This study assessed how vaccine attributes and socio-demographic factors affect the acceptability of leptospirosis vaccine; and estimated individuals' willingness to pay for leptospirosis vaccine. A discrete choice experiment was conducted among leptospirosis and non-leptospirosis case respondents (n = 342) living in Metro Manila. Random Parameters Logit model was used to estimate the relative importance of vaccine attributes and socio-demographic variables on respondents' leptospirosis vaccination choice decision. The estimated model coefficients were used to derive implicit prices and willingness to pay for leptospirosis vaccine. Both case respondents preferred leptospirosis vaccine with 70-100% efficacy, mild to moderate risk of side-effects, given in a single shot, and at a lower price. Non-leptospirosis case respondents preferred a vaccine with 7 to 10 y of protection, while leptospirosis case respondents preferred a vaccine with 10 y protection. The probability of leptospirosis vaccination acceptance was affected by respondents' age, education, family size and income, proximity of home to rivers and sewers, and leptospirosis awareness level. Respondents' willingness to pay for leptospirosis vaccine (US$ 31.14-US$ 65.89) was higher than the Japanese retail price (US$ 21.60-US$ 24.00). Our findings indicated significant potential for introducing leptospirosis vaccine in the Philippine vaccine market. Delivery strategies to ensure equitable access to future leptospirosis vaccine are recommended.
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Leptospirosis/prevención & control , Vacunación/psicología , Adulto , Femenino , Humanos , Leptospirosis/inmunología , Persona de Mediana Edad , Modelos Teóricos , Adulto JovenRESUMEN
OBJECTIVES: To determine the occurrence and antimicrobial resistance of pathogenic vibrios from green mussel, Perna viridis in bacoor bay cavite. METHODS: Vibrios were isolated using TCBS agar and confirmed using API Identification kit. The relationship between the density of vibrios and environment parameters such as months, harvest sites and other physico-chemical parameters of water was determined. The isolated vibrios were subjected to antibiotic resistance testing to determine the resistance patterns.RESULTS: Pathogenic vibrios were isolated in all of the 90 mussel samples. Of the 183 vibrio isolates, 75 strains were V. alginolyticus and 53 strains belonged to V. cholerae wherein 18 (34%) of these were V. cholerae serotype O1. Forty nine (49) strains belonged to V. parahaemolyticus and six were V. vulnificus. Using the regression analysis, salinity, water temperature and ph have significant correlation on the density of vibrios (p=0.0309), with regression model, total vibrios = -16990763 + 145858 Salinity + 186808 Temperature + 1037886 pH. In the antimicrobial resistance assay,ampicillin had the highest drug resistance (37.8%) followed by nalidixic acid (10.4%), tetracycline (10.4%) and co-trimoxazole (9.3%).CONCLUSION: Pathogenic vibrios were isolated in mussel of Bacoor, Cavite and can be predicted using salinity, temperature and pH of the water. Thirty six percent (36%) of Vibrio isolates were resistance to ampicillin.
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Animales , Salinidad , Temperatura , Ampicilina , Resistencia a Medicamentos , Ácido Nalidíxico , Tetraciclina , Combinación Trimetoprim y SulfametoxazolRESUMEN
OBJECTIVES: Rats have been identified as primary sources of leptospires in the environment. This study aimed to characterize Leptospira species circulating among rats found in public markets in Iloilo City, Philippines. METHODS: Dark-field microscopy was used to determine leptospire presence in tissue cultures. Isolates from the cultures were characterized via serotyping with monoclonal and polyclonal antibodies. To characterize the antibodies present in rat sera, the microscopic agglutination test (MAT) was used. RESULTS: In this study, 19 rats were obtained from 7 markets in Iloilo City. Three(3) rats (15%.8) were found to harbor leptospires in the urinary bladder (2) and kidney (1). Serotyping of the isolates showed that they did not belong to previously reported common serovars in the Philippines such as Manilae, Losbanos, Javanica or Grippotyphosa. Using another panel of polyclonal antibodies, it was shown that the isolates belonged to serovar lcterohaemorrhagiae. The MAT results showed that 16 (84.2%) serum samples were positive for anti-Leptospira antibodies. The most common infecting serovars were Autumnails (47.4%), Pomona (42.1%) Copenhageni (36.8%), and Hebdomadis (31.6%) other infecting serovars identified were lcterohaemorrhagiae, Poi, Grippotyphosa, Patoc, and Pyrogenes. CONCLUSION: The results of the present study provide baseline data on the circulating leptospiral serovars in iloilo City. Results suggest the possible role of rats in disease transmission in the study areas.
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Ratas , Animales , Leptospirosis , Anticuerpos Monoclonales , Serotipificación , Cultura , AglutinaciónRESUMEN
Leptospirosis is a zoonosis caused by pathogenic Leptospira spp. Most of the outbreaks of leptospirosis occur after floods caused by heavy rain in countries where Leptospira spp. are endemic. It has been believed that the overflow of seawater rarely causes outbreaks of leptospirosis because the leptospires are killed by salt water. On 8 November 2013, a storm surge caused by Super Typhoon Haiyan (Yolanda) inundated the entire coastal areas of Tacloban and Palo in Leyte, Philippines. The present study was carried out in order to determine whether the environmental leptospires in soil were able to survive after the storm surge in the affected areas. We collected 23 wet soil samples along the coastal areas of Tacloban and Palo 2 months after the storm surge. The samples were suspended in HEPES buffer, and the supernatants were cultured in liquid or semisolid Korthof's medium supplemented with five antimicrobial agents to inhibit the growth of contaminants. Leptospires were isolated from primary cultures of 22 out of 23 samples. The DNA of pathogenic Leptospira species was detected in 11 samples (47.8%) by analysis of flaB by nested PCR. Eventually, two pathogenic Leptospira strains were isolated and showed the highest 16S rRNA gene sequence similarity to Leptospira kmetyi. When these isolates were experimentally mixed with soil, they were found to survive in seawater for 4 days. These results show the possibility that leptospires living in soil survived after the storm surge. Our findings may serve as a warning that when seawater inundates the land during a storm surge or a tsunami, an outbreak of leptospirosis could occur in the disaster-stricken area.
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Leptospira/aislamiento & purificación , Microbiología del Suelo , Tormentas Ciclónicas , Desastres , Humanos , Leptospira/clasificación , Leptospira/genética , Leptospirosis/microbiología , Filipinas , Reacción en Cadena de la PolimerasaRESUMEN
Leptospirosis is a zoonotic infection that is caused by the pathogenic species of Leptospira. Rats are the most important reservoirs of these organisms. Our study aimed to characterize Leptospira isolates from humans and rats and elucidate the Leptospira-rat-human relationship in Luzon, Philippines. Forty strains were isolated from humans and rats. The isolates were confirmed to be Leptospira and pathogenic through rrl- and flaB-PCR, respectively. Around 73% of the isolates were found to be lethal to hamsters. Serotyping showed that there were mainly three predominant leptospiral serogroups in the study areas namely Pyrogenes, Bataviae, and Grippotyphosa. Gyrase B gene sequence analysis showed that all the isolates belonged to Leptospira interrogans. Most had 100% similarity with serovar Manilae (15/40), serovar Losbanos (8/40), and serogroup Grippotyphosa (8/40). Strains from each group had highly identical pulsed-field gel electrophoresis patterns and were further grouped as A (Pyrogenes, 14), B (Bataviae, 8), and C (Grippotyphosa, 10). Results further revealed that similar serotypes were isolated from both humans and rats in the same areas. It is suggested that these three predominant groups with highly similar intra-group PFGE patterns may have been primarily transmitted by rats and persistently caused leptospirosis in humans particularly in the Luzon islands.
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Reservorios de Enfermedades , Leptospira interrogans/clasificación , Leptospira interrogans/aislamiento & purificación , Leptospirosis/epidemiología , Leptospirosis/veterinaria , Enfermedades de los Roedores/epidemiología , Enfermedades de los Roedores/transmisión , Animales , ADN Bacteriano/química , ADN Bacteriano/genética , Modelos Animales de Enfermedad , Transmisión de Enfermedad Infecciosa , Electroforesis en Gel de Campo Pulsado , Genotipo , Humanos , Leptospira interrogans/genética , Leptospira interrogans/inmunología , Leptospirosis/microbiología , Leptospirosis/transmisión , Masculino , Mesocricetus , Epidemiología Molecular , Datos de Secuencia Molecular , Tipificación Molecular , Filipinas/epidemiología , Reacción en Cadena de la Polimerasa , Ratas , Enfermedades de los Roedores/microbiología , Análisis de Secuencia de ADN , Serogrupo , Análisis de Supervivencia , Zoonosis/microbiología , Zoonosis/transmisiónRESUMEN
BACKGROUND: Leptospirosis is a global zoonosis caused by pathogenic Leptospira. The non-specific clinical signs and symptoms of leptospirosis lead to its misdiagnosis. To date, there is still no reliable rapid test kit that can accurately diagnose leptospirosis at bedside or in field. In this research, with the ultimate goal of formulating a rapid and accurate diagnostic tool for leptospirosis, we aimed to identify leptospiral proteins excreted in urine of infected hamsters, which are thought to mimic Weil's disease. RESULTS: Hamsters were subcutaneously infected with leptospires, and the general attributes of urine as well as the proteins excreted in it were examined. Some leptospiral proteins were found to be excreted in the urine from the early phase of infection. The most important finding of this study was the detection of the lipid-metabolizing enzyme, 3-hydroxyacyl-CoA dehydrogenase (HADH), before the onset of illness, when leptospires were not yet detected in the urine of infected hamsters. CONCLUSIONS: This is the first report on the detection of leptospiral HADH in the host urine, which may be a possible candidate leptospiral antigen that can be used in the early diagnosis of human and animal leptospirosis.
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3-Hidroxiacil-CoA Deshidrogenasa/orina , Leptospira/enzimología , Leptospirosis/patología , Orina/química , Animales , Cricetinae , Modelos Animales de Enfermedad , Femenino , Masculino , MesocricetusRESUMEN
Weil's disease, the most severe form of leptospirosis, is characterized by jaundice, haemorrhage and renal failure. The mechanisms of jaundice caused by pathogenic Leptospira remain unclear. We therefore aimed to elucidate the mechanisms by integrating histopathological changes with serum biochemical abnormalities during the development of jaundice in a hamster model of Weil's disease. In this work, we obtained three-dimensional images of infected hamster livers using scanning electron microscope together with freeze-cracking and cross-cutting methods for sample preparation. The images displayed the corkscrew-shaped bacteria, which infiltrated the Disse's space, migrated between hepatocytes, detached the intercellular junctions and disrupted the bile canaliculi. Destruction of bile canaliculi coincided with the elevation of conjugated bilirubin, aspartate transaminase and alkaline phosphatase levels in serum, whereas serum alanine transaminase and γ-glutamyl transpeptidase levels increased slightly, but not significantly. We also found in ex vivo experiments that pathogenic, but not non-pathogenic leptospires, tend to adhere to the perijunctional region of hepatocyte couplets isolated from hamsters and initiate invasion of the intercellular junction within 1 h after co-incubation. Our results suggest that pathogenic leptospires invade the intercellular junctions of host hepatocytes, and this invasion contributes in the disruption of the junction. Subsequently, bile leaks from bile canaliculi and jaundice occurs immediately. Our findings revealed not only a novel pathogenicity of leptospires, but also a novel mechanism of jaundice induced by bacterial infection.
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Hepatocitos/microbiología , Uniones Intercelulares/microbiología , Ictericia/etiología , Leptospira interrogans/fisiología , Leptospirosis/complicaciones , Enfermedad de Weil/complicaciones , Alanina Transaminasa/metabolismo , Fosfatasa Alcalina/metabolismo , Animales , Aspartato Aminotransferasas/metabolismo , Traslocación Bacteriana/fisiología , Bilirrubina/metabolismo , Cricetinae , Modelos Animales de Enfermedad , Hepatocitos/patología , Hepatocitos/ultraestructura , Uniones Intercelulares/patología , Uniones Intercelulares/ultraestructura , Ictericia/metabolismo , Leptospirosis/metabolismo , Masculino , Mesocricetus , Enfermedad de Weil/metabolismoRESUMEN
Leptospirosis caused by drinking water has not been as frequently reported as percutaneous infection. Resistance to oral infection by pathogenic Leptospira was examined in an experimental hamster infection model. The results suggested some natural defenses against oral infection by Leptospira. First, we found that characteristic linear agglutination of Leptospira rapidly occurs when mixed with human saliva. That human saliva attenuated the infectivity of the treated leptospires by its agglutination activity suggested saliva to be the first line of defense against oral infection by leptospires. Second, only 10(1) Leptospira organisms caused death after submucosal injection into oral mucosa in hamsters, but oral infection with drinking water containing 10(5) organisms/mL did not cause death. This result showed that the mucosa plays the role of a physical barrier. Third, hamsters intragastrically infected by leptospires, with doses lethal to hamsters in oral infection, showed no signs of illness, which suggested that gastric acid plays an important role in preventing oral infection. Based on these results, saliva, mucosa, and gastric acid make up a natural defense, which confers high resistance to hosts against oral infection by leptospires.
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Leptospira interrogans/inmunología , Leptospirosis/inmunología , Mucosa Bucal/inmunología , Saliva/inmunología , Aglutinación/efectos de los fármacos , Aglutinación/inmunología , Animales , Cricetinae , Ácido Gástrico/fisiología , Glicósido Hidrolasas/metabolismo , Calor , Humanos , Concentración de Iones de Hidrógeno , Masculino , Mesocricetus , Mitógenos/farmacología , Ácido Peryódico/farmacologíaRESUMEN
Leptospirosis is caused by pathogenic species of Leptospira. The aim of this study was to determine and characterize the pathogenicity of four dominant Leptospira isolates prevailing among rats in the Philippines. The isolates were Leptospira interrogans serovar Manilae strain K64, L. interrogans serovar Losbanos strain K37, L. interrogans serovar Ratnapura strain K5 and Leptospira borgpetersenii serovar Javanica strain K6. Pathogenicities were studied using hamsters, which reproduce severe human leptospirosis. The minimum lethal doses were 10(0) (â=â1) leptospires for K64, K37 and K5, and 10(1) leptospires for K6. Weight loss amongst the Leptospira-infected hamsters was observed from 1 day before death (K64-, K37- and K5-infected hamsters) to as much as 1 week before death for K6-infected hamsters. Similar and varied gross and microscopic lesions were observed amongst infected hamsters, even for strains belonging to the same species (i.e. L. interrogans). The most significant and common histopathological findings were congestion of the glomerulus, disarrangement of hepatic cords and erythrophagocytosis. Other findings were foamy splenic macrophages for K6, severe petechial pulmonary haemorrhage for K64, and hematuria and severe pulmonary congestion for K37. Immunostaining and culture revealed the presence of leptospires in different organs of the infected hamsters. Based on these results, Leptospira isolates from rats in the Philippines were shown to be highly virulent, causing pulmonary haemorrhage, severe hepato-renal damage and death in hamsters even at lower doses. The present findings on experimental leptospirosis support clinical data showing that patients with severe manifestations of leptospirosis, such as pulmonary haemorrhage, are increasing in the Philippines. These findings may serve as a basis to strengthen the early diagnosis and treatment of human leptospirosis.
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Leptospira/aislamiento & purificación , Leptospira/patogenicidad , Leptospirosis/microbiología , Leptospirosis/patología , Estructuras Animales/microbiología , Estructuras Animales/patología , Animales , Peso Corporal , Cricetinae , Modelos Animales de Enfermedad , Leptospira/clasificación , Filipinas , Ratas , Serotipificación , Análisis de Supervivencia , VirulenciaRESUMEN
Leptospirosis is a serious public health concern in the Philippines, not only because of its increasing incidence rate, but also because of its significant health and economic impacts. Despite its relatively high seroprevalence, knowledge on the economic burden of disease, particularly on the value that the society places on disease prevention remains limited. Obtaining such information is important within the context of public health policy. This study was conducted in Metro Manila to determine the economic burden of leptospirosis, by asking respondents about their willingness to contribute to labor (WTCL) for the prevention of leptospirosis. The respondents pledged an average labor contribution of 10.66 h/month. The average WTCL corresponded to a monetary value of US$4.01 per month when valued using the opportunity cost of labor (leisure rate of time). From the monetized labor contribution, the total economic value of preventing leptospirosis was estimated at US$124.97 million per annum, which represents 1.13% of Metro Manila's gross domestic product (GDP). Estimates from a Tobit regression model identified the respondents' knowledge regarding leptospirosis, the susceptibility of their homes to flooding, and the proximity of their homes to sewers as significant factors to consider when developing resource contribution programs for leptospirosis prevention. More efforts need to be made in developing community level preventive programs, and in improving public's knowledge and awareness about leptospirosis.
Asunto(s)
Política de Salud/economía , Leptospirosis/economía , Leptospirosis/prevención & control , Salud Urbana/economía , Adolescente , Adulto , Femenino , Humanos , Masculino , Persona de Mediana Edad , Modelos Econométricos , Filipinas , Adulto JovenRESUMEN
Leptospirosis is an infectious disease caused by the spirochete bacteria Leptospira spp. and is commonly found throughout the world. Diagnosis of leptospirosis performed by culture and microscopic agglutination tests is laborious and time-consuming. Therefore, we aimed to develop a novel immunochromatography (ICG)-based method for detecting Leptospira antigen in the urine of patients and animals. We used the 1H6 monoclonal antibody (MAb), which is specific to the lipopolysaccharide (LPS) that is common among Leptospira spp. The MAb was coupled to 40-nm-diameter colloidal gold, and the amounts of labeled antibody and immobilized antibody were 23 µg and 2 µg per test, respectively. Several strains of Leptospira and other bacterial species were used to evaluate the sensitivities and specificities of the assays we developed. The detection limit of the assays was 10(6) cells/ml when disrupted whole bacterial cells were used. The assays were Leptospira specific since they did not cross-react with non-Leptospira bacteria used in the study. Application of diagnostic assays was done on the urine samples of 46 Leptospira-infected hamsters, 44 patients with suspected leptospirosis, and 14 healthy individuals. Pretreatment of the urine samples by boiling and centrifugation (for ultrafiltration and concentration) eliminated nonspecific reactions that occurred in the assay. The sensitivity and specificity of the ICG-based lateral flow assay (LFA) were 89% and 87%, respectively, which were higher than those of the dipstick assay, which were 80% and 74%, respectively. In summary, this ICG-based LFA can be used as an alternative diagnostic assay for leptospirosis. Further development is still necessary to improve the assay.
Asunto(s)
Anticuerpos Monoclonales/inmunología , Cromatografía de Afinidad/métodos , Leptospira/inmunología , Leptospira/aislamiento & purificación , Leptospirosis/diagnóstico , Lipopolisacáridos/orina , Animales , Anticuerpos Antibacterianos/inmunología , Antígenos Bacterianos/inmunología , Cricetinae , Oro Coloide , Humanos , Leptospirosis/inmunología , Lipopolisacáridos/inmunología , Sensibilidad y EspecificidadRESUMEN
Strain Eri-1(T) was isolated from a water sample on the campus of Kyushu University, Fukuoka, Japan. The motility and morphology of the isolate were similar to those of members of the genus Leptospira, but the spiral structure of the isolate was sharper under dark-field microscopy. Cells were 10.6 ± 1.3 µm long and 0.2 µm in diameter, with a wavelength of 0.9 µm and an amplitude of 0.4 µm. Strain Eri-1(T) grew in Korthof's medium at both 13 and 30 °C, and also in the presence of 8-azaguanine. 16S rRNA gene-based phylogenetic analysis placed strain Eri-1(T) within the radiation of the genus Leptospira where it formed a unique lineage within the clade of the known saprophytic species of the genus Leptospira. The strain was not pathogenic to hamsters. Strain Eri-1(T) exhibited low levels (11.2-12.6 %) of similarity by DNA-DNA hybridization to the three most closely related species of the genus Leptospira. The DNA G+C content of the genome of strain Eri-1(T) was 42.5 ± 0.1 mol%. These results suggest that strain Eri-1(T) represents a novel species of the genus Leptospira, for which the name Leptospira idonii sp. nov. is proposed. The type strain is Eri-1(T) ( = DSM 26084(T) = JCM 18486(T)).