Occurrence of Orientia tsutsugamushi in small mammals from Thailand

Extensive sampling of small mammals was conducted in eight provinces of Thailand between September 9, 1992 and April 29, 2001. A total of 3,498 specimens representing 22 species were collected. Eighty-eight percent (3,089 of 3,498) of the animals were collected from a region in Chiangrai Province, which is commonly recognized as endemic for human scrub typhus. Blood and tissue samples from each animal were tested for the presence of Orientia tsutsugamushi, the etiologic agent of scrub typhus. The predominant species collected were Rattus rattus (53%, n = 1,863), R. losea (18%, n = 638), Bandicota indica (16%, n = 564), and R. exulans (4%, n = 146). Orientia tsutsugamushi was detected in 10 of the 22 species of mammals that included R. bukit (25% infected, 1 of 4), R. rattus (23%, 419 of 1,855), R. argentiventer (22%, 5 of 23), R. berdmorei (22%, 2 of 9), R. losea (13%, 82 of 638), B. indica (9%, 52 of 564), R. koratensis (8%, 1 of 12), B. savilei (3%, 1 of 30), R. exulans (1%, 2 of 146), and Tupaia glis (2%, 1 of 49). Infected animals were found in Chiangrai (18% infected, 563 of 3,084), Bangkok (11%, 1 of 9), Sukothai (3%, 1 of 30), and Nonthaburi (1%, 1 of 69) Provinces. The implications towards scrub typhus maintenance and transmission are discussed.     

A serological investigation of leptospirosis in sows from central Thailand

Leptospirosis is a major pig-associated zoonosis worldwide. There are also human occupational disease exposure risks. For better public health and sanitation, the prevalence of this disease was investigated. Four hundred sera were obtained from sows in central Thailand during August 2004 to January 2005 and examined with 20 reference leptospira serovars by a microscopic agglutination test (MAT). The results showed that 10% of samples gave a positive reaction. The most prevalent serovar was grippotyphosa which accounted for 55% of all positive cases. Other minor serovars were canicola and a non-pathogenic strain (patoc). It follows that, the sow may be one of the disease transmitting sources for humans in this area. The disease correlation between pigs, humans and the environments should be evaluated.     

Risk factors associated with leptospirosis in northeastern Thailand, 1998

Leptospirosis is a zoonotic disease of worldwide distribution caused by spirochetes of the genus Leptospira. Humans are infected through direct contact with infected animals or through exposure to fresh water or soil contaminated by infected animal urine. Leptospirosis is characterized by acute fever that can be followed by a more severe, sometimes fatal illness that may include jaundice and renal failure (Weil's disease), meningitis, myocarditis, hemorrhagic pneumonitis, or hemodynamic collapse. To identify potential risk factors for leptospirosis in Thailand, we conducted a matched case-control study in Nakornratchasrima Province of the northeastern region. Fifty-nine cases and 118 controls were included in the study. Four activities in the two weeks prior to illness were independently associated with leptospirosis infection: walking through water (odds ratio [OR] = 4.9, 95% confidence interval [CI] = 1.7-14.1), applying fertilizer in wet fields for more than 6 hr a day (OR = 3.4, 95% CI = 1.5-7.8), plowing in wet fields for more than 6 hr a day (OR = 3.5, 95% CI = 1.1-11.6), and pulling out rice plant sprouts in wet fields for more than 6 hr a day (OR = 3.1, 95% CI = 1.02-9.3). Identification of these risk factors on admission might prove useful for early diagnosis and treatment of leptospirosis in Thailand.     

Accuracy of loop-mediated isothermal amplification for diagnosis of human leptospirosis in Thailand

There is a lack of diagnostic tests for leptospirosis in technology-restricted settings. We developed loop-mediated isothermal amplification (LAMP) specific for the 16S ribosomal RNA gene (rrs) of pathogenic and intermediate group Leptospira species. The lower limit of detection was 10 genomic equivalents/reaction, and analytical specificity was high; we observed positive reactions for pathogenic/intermediate groups and negative reactions for non-pathogenic Leptospira species and other bacterial species. We evaluated this assay in Thailand by using a case-control study of 133 patients with laboratory-proven leptospirosis and 133 patients with other febrile illnesses. Using admission blood, we found that the rrs LAMP showed positive results in 58 of 133 cases (diagnostic sensitivity = 43.6, 95% confidence interval [CI] = 35.0-52.5) and in 22 of 133 controls (diagnostic specificity = 83.5, 95% CI = 76.0-89.3). Sensitivity was high for 39 patients who were culture positive for Leptospira spp. (84.6, 95% CI = 69.5-94.1). The rrs LAMP can provide an admission diagnosis in approximately half of patients with leptospirosis, but its clinical utility is reduced by a lower specificity.     

Survey of asthma control in Thailand

OBJECTIVE: The aim of the study was to determine whether asthma management in Thailand is succeeding in achieving the levels of control, specified in national and international asthma guidelines. METHODOLOGY: Adults with asthma in Bangkok, Chiang Mai, Songkhla, and Khon Kaen were interviewed, and we have reported on their asthma severity, morbidity, control, perception of asthma, and healthcare use. RESULTS: A total of 466 asthma sufferers were interviewed. The burden of asthma was high, with 14.8% of respondents being hospitalized for their asthma in the past year. One-quarter of those surveyed had lost workdays as a result of their asthma, and most patients felt that their lifestyle was limited. The majority of respondents had intermittent asthma (62.9%), 10.5% had mild persistent asthma, 17.6% had moderate persistent asthma, and 9.0% had severe persistent asthma; increasing severity was significantly associated with increased emergency healthcare use (P < 0.00001). Asthma sufferers greatly underestimated the severity of their condition. Only 36.0% used reliever medication, and use of inhaled corticosteroids was low at 6.7%. Understanding of the inflammatory basis of asthma was poor. Few patients underwent lung function tests or took peak flow meter readings. CONCLUSIONS: The burden of asthma is high in Thailand, and guidelines are not being followed. Encouraging greater use of inhaled corticosteroids will be an important step towards improving asthma control.     

Respiratory mechanics in small newborn mammals

The passive mechanical properties of the lung and respiratory system have been measured in newborn opossums, hamsters and mice, which, by ranging in size between 0.3 and 3 are among the smallest newborn mammals. Compared to newborns of larger species, resistances are not increased as much as compliances are decreased. This indicates that the geometry of the lung changes in the smallest species, and by protecting airway resistance limits the energetic losses determined by breathing at high frequencies. In the 0.3 g newborn opossum the lung is disproportionately large, possibly indicating the existence of a lower limit in lung size beyond which the design of the mammalian lung would not be functionally efficient. Finally, passive time constants were 40-60 msec (without the upper airway resistance). These values are shorter than in larger species, and several considerations indicate that they could be even shorter during spontaneous breathing. However, they are not compatible with the extremely brief inspiratory times and large tidal volumes which would have been required to sustain the high oxygen requirements expected for mammals of such a small size. This therefore supports the hypothesis that in these small animals the mechanical properties of the respiratory system can pose a constraint to the rate of resting ventilation and, possibly, to that of oxygen consumption.     

Epidemiology and characterization of leptospirosis at an urban and provincial site in Thailand

Patients with FUOs at the Children's Hospital in Bangkok and the Chao Phya Abhai Bhu Bejhr Hospital in Prachinburi were screened for leptospirosis by blood and urine culture in addition to microagglutination testing of their serum. Animal populations in urban and periurban areas of Bangkok were surveyed for evidence of leptospira infection. Three rural sites near the Prachinburi Provincial Hospital were also surveyed. The rodents' and domestic animals' blood, urine, and/or kidney cell samples were cultured for leptospira. Sera from these animals were also tested for leptospira antibody. The bataviae serovar was the most commonly detected leptospiral agent in both man and animals. Presenting symptoms varied with age with children showing primarily fever, vomiting, headache, abdominal and generalized muscle pain and diarrhea whereas adults had fever, headache, anorexia, muscle pain and constipation. Blood samples from patients suspected of having leptospirosis were tested for antibody by the MAT and cultured in EMJH media. The following serogroups were identified: bataviae, autumanalis, javanica, hebdomadis, and pyrogens. Leptospirosis incidence in humans was much higher in the rainy/flooding year of 1983 compared to the relatively dry year of 1984. Results of our animal surveillance studies indicate that in addition to rats, which have previously been mentioned, dogs, bandicoots, cattle and pigs could be the source of human leptospirosis infection in both urban and provincial locations in Thailand.     

Endocrine function in naturally long-living small mammals

The complex, highly integrative endocrine system regulates all aspects of somatic maintenance and reproduction and has been widely implicated as an important determinant of longevity in short-lived traditional model organisms of aging research. Genetic or experimental manipulation of hormone profiles in mice has been proven to definitively alter longevity. These hormonally induced lifespan extension mechanisms may not necessarily be relevant to humans and other long-lived organisms that naturally show successful slow aging. Long-lived species may have evolved novel anti-aging defenses germane to naturally retarding the aging process. Here, we examine the available endocrine data associated with the vitamin D, insulin, glucocorticoid and thyroid endocrine systems of naturally long-living small mammals. Generally, long-living rodents and bats maintain tightly regulated lower basal levels of these key pleiotropic hormones than shorter lived rodents. Similarities with genetically manipulated long-lived rodent models of aging suggest that evolutionary well-conserved hormonal mechanisms are integrally involved in lifespan determination.     

Accuracy of a commercial IgM ELISA for the diagnosis of human leptospirosis in Thailand

The Leptospira immunoglobulin M enzyme-linked immunosorbent assay (IgM ELISA) has been recommended for the rapid diagnosis of leptospirosis in endemic areas. We conducted a retrospective case-control study of 218 patients (109 leptospirosis cases confirmed by Leptospira culture and/or microscopic agglutination test and 109 control patients with acute febrile illness) to evaluate the diagnostic accuracy of a commercial IgM ELISA (Panbio) in northeast Thailand. Paired serum samples taken on admission and at least 10 days after the onset of symptoms were tested. Using the cutoff value recommended by the manufacturer (11 Panbio units), sensitivity and specificity of IgM ELISA on paired sera were 90.8% and 55.1%. A receiver operating characteristic curve was used to determine the optimal cutoff value. This was 20 Panbio units, which gave a sensitivity and specificity of 76.1% and 82.6%, respectively, on paired sera. We conclude that using either cutoff value, the accuracy of IgM ELISA is limited in our setting.     

Surveillance of leptospirosis after flooding at Loei Province, Thailand by year 2002

In this surveillance, suspected leptospirosis patients in Loei Hospital, Loei Province were studied by conventional methods of cultivation and microscopic agglutination test (MAT) during July-October, 2002. It was found that 63% of 64 admitted patients and 35% of 34 outpatients were found positive by leptospire cultivation. Antibodies determined by MAT were positive in 78% of 63 admitted patients. Particularly, the five most common agglutinating antibodies were reactive with serovars bratislava (57%), autumnalis (48%), new (38%), australis (37%) and bangkok (29%). The MAT results of 15 OPD patients were 67% positive with the following five serovars, including bratislava (47%), new (20%), bangkok (7%), ranarum (7%) and australis (7%). Accordingly, preventive strategies against leptospirosis outbreaks after flooding in Thailand should be undertaken, including the prompt treatment of the disease in this endemic area.     

北京市小型兽类鼠疫监测结果

目的了解北京市自然环境中小型兽类种群组成和种群密度,并检测是否存在鼠疫耶尔森氏菌感染。方法根据动植物历史分布资料在门头沟区、延庆县、怀柔区、密云县设立监测点,在2009、2010年用夹夜法捕捉小型兽类并鉴定物种、计算密度。笼捕法捕捉活鼠,心脏取血后进行鼠疫F1抗体检测。结果北京市2009、2010年小型兽类(主要为啮齿类)密度分别为7.01只/100夹次和3.27只/100夹次。捕获小型兽类10种,其中啮齿类动物8种,食虫目1种,食肉目1种。社鼠、大林姬鼠和黑线姬鼠种群密度和构成最高,2009、2010年3种鼠合计占夹夜法全部捕鼠量的93.81%和85.33%。鼠疫血清学检测标本624件,鼠疫耶尔森氏菌F1抗体均为阴性。结论北京市存在已确定的鼠疫可染疫动物社鼠、大林姬鼠和黑线姬鼠,且为优势种群,目前血清学监测结果暂未发现鼠疫菌感染。     

Serological evidence of Thailand virus-related hantavirus infection among suspected leptospirosis patients in Kandy, Sri Lanka

A cross-sectional study was undertaken to determine the current prevalence of leptospirosis and hantaviral infections, and the socio-demographic characteristics and risk factors of infected patients, in Kandy, Sri Lanka. This report discusses the serological evidence of hantavirus infections among 105 suspected leptospirosis patients, 8 of whom had hantavirus antibodies. Serotyping ELISA showed that these 8 patients had high optical density values for Thailand virus. Most of the sera showed that the focus reduction neutralization test titer against Thailand virus was higher than that against Seoul virus, thereby suggesting that the hantaviral antibodies found in Sri Lanka are different from Seoul virus but closely related to Thailand virus. These findings imply that the hantaviral infection found in Kandy, Sri Lanka appears to be due to a virus similar to Thailand virus. Epidemiological analysis revealed that the association between hantavirus infection and socio-demographic characteristics was not statistically significant.     

Prognostic factors of death in leptospirosis: a prospective cohort study in Khon Kaen, Thailand.

OBJECTIVES: To determine the prognostic factors of death in leptospirosis. METHODS: A prospective cohort study was conducted. One hundred and twenty one patients with clinically compatible leptospirosis, serologically confirmed, were recruited in this study. Clinical presentations and biochemical parameters on admission were selected as input variables for survival analysis. Multivariable Cox regression model was used to identify the prognostic factors of death. RESULTS: Most patients were male (94.2%), with the mean +/-SD age of 38+/-13.4 years; 77.4% of them were farmers. Among the 121 patients, 1206 patient-days were observed. Seventeen patients died. Overall mortality rate was 1.4 per 100 patient-days (95% confidence interval [CI]: 0.9-2.3). The causes of death included: a) pulmonary hemorrhage in eight (47.1%) patients; b) complicated acute renal failure in three (17.6%) patients; c) multiple organ failure in three (17.6%) patients; d) acute respiratory distress syndrome in two (11.8%) patients, and e) irreversible shock in one (5.9%) patient. Four independent risk factors associated with the mortality were identified, including hypotension (relative risk [RR], 10.3; 95% CI, 1.3-83.2; P<0.05); oliguria (RR, 8.8; 95% CI, 2.4-31.8; P<0.01); hyperkalemia (RR, 5.9; 95% CI, 1.7-21; P<0.01), and presence of pulmonary rales (RR, 5.2; 95% CI, 1.4-19.9; P<0.05). CONCLUSION: The presence of oliguria, hyperkalemia, pulmonary rales, or hypotension on admission in patients with leptospirosis indicated high risk of death. Intensive care and early intervention should be provided for patients who present with these risk factors.     

Bartonella species in small mammals and their ectoparasites in Taiwan

Bartonella spp. prevalence in small mammals and their ectoparasites was investigated in Taiwan. Blood samples were obtained from 66 rats, 20 shrews, 276 mites (Laelaps spp.), 74 fleas (Xenopsylla cheopis), 81 lice (Polyplax spp.), and 47 ticks (41 Dermacentor spp. and 6 Ixodes spp.). Bartonellae were isolated or detected in 27 (31.4%) animals. Bartonella DNA was detected in 48 (64.9%) fleas and 11 (64.7%) pooled lice samples, but not in mite and tick samples. Bartonella phoceensis, B. queenslandensis, B. tribocorum, B. elizabethae, and B. rattimassiliensis were isolated or detected in bacteremic mammals. For the first time in Taiwan, B. tribocorum, B. elizabethae, B. queenslandensis, and a B. rochalimae-like strain were detected in fleas, and B. tribocorum, B. phoceensis, and B. rattimassiliensis were detected in lice obtained from small mammals. A broader range of Bartonella species was identified in the ectoparasites than in the small mammals.