Serologic evidence for an epizootic dengue virus infecting toque macaques (Macaca sinica) at Polonnaruwa, Sri Lanka.
(17/11802)
Dengue is one of the most rapidly emerging diseases in the tropics. Humans are the principal reservoir of dengue viruses. It is unclear if nonhuman primates also serve as a reservoir of human dengue viruses under certain conditions. In this study, a cross-sectional serologic survey was carried out to characterize the pattern of transmission of a recently identified dengue virus among toque macaques in Sri Lanka. The results indicated that an epizootic dengue virus was active among the macaques. A single epizootic had taken place between October 1986 and February 1987 during which 94% of the macaques within the 3 km2 study site were exposed to the virus. The epizootic was highly focal in nature because macaques living 5 km from the study population were not exposed to the virus. The transmission of dengue viruses among macaques in the wild may have important public health implications. (+info)
Natural mass infection by heterophyid metacercariae in aquacultured Japanese eel in Taiwan.
(18/11802)
A natural mass infection of heterophyid metacercariae in aquacultured Japanese eel Anguilla japonica in Taiwan was observed. Of the 28,000 adult eels in 2 ponds, about 25,000 (90%) showed swollen, cloudy and white eyes. Although morbidity was about 90%, there was no mortality among the affected eels. Histopathological sections showed edema and hemorrhage of the eye. Numerous metacercariae were observed in the muscle tissues around the eyeball, the subcutaneous tissue and even in the cartilage. Of the 6 eels digested with artificial gastric juice, all were found to contain metacercariae in their muscle tissues. The average number of metacercariae recovered from the 6 eels was 1219, with a range of 50 to 3762. These metacercariae, when fed orally to immunodeficient (scid) mice, developed into adult worms which were identified as Procerovum cheni Hsu 1950. The naturally infected eels were transferred to a new pond without snails and their eye lesions were not apparent anymore after 2 wk. In a follow-up investigation, 19 of 20 apparently healthy eels in a nearby aquaculture farm were found to harbour metacercariae in their muscles. However, the number of the metacercariae ranged from 1 to 14, with an average of 4.21. This is the first report of heterophyid metacercariae causing mass morbidity in aquacultured eels. (+info)
Molecular markers demonstrate that the first described multidrug-resistant Mycobacterium bovis outbreak was due to Mycobacterium tuberculosis.
(19/11802)
We genetically characterized multidrug-resistant Mycobacterium tuberculosis complex strains which caused a nosocomial outbreak of tuberculosis affecting six human immunodeficiency virus (HIV)-positive patients and one HIV-negative staff member (E. Bouvet, E. Casalino, G. Mendoza-Sassi, S. Lariven, E. Vallee, M. Pernet, S. Gottot, and F. Vachon, AIDS 7:1453-1460, 1993). The strains showed all the phenotypic characteristics of Mycobacterium bovis. They presented a high copy number of IS6110, the spacers 40 to 43 in the direct repeat locus, and the mtp40 fragment. They lacked the G-A mutation at position 285 in the oxyR gene and the C-G mutation at position 169 in the pncA gene. These genetic characteristics revealed that these were dysgonic, slow-growing M. tuberculosis strains mimicking the M. bovis phenotype, probably as a consequence of cellular alterations associated with the multidrug resistance. Spoligotyping and IS6110 restriction fragment length polymorphism (RFLP) analysis confirmed that the outbreak was due to a single strain. However, the IS6110 RFLP pattern of the strain isolated from the last patient, diagnosed three years after the index case, differed slightly from the patterns of the other six strains. A model of a possible genetic event is presented to explain this divergence. This study stresses the value of using several independent molecular markers to identify multidrug-resistant tubercle bacilli. (+info)
Analysis with a combination of macrorestriction endonucleases reveals a high degree of polymorphism among Bordetella pertussis isolates in eastern France.
(20/11802)
From 1990 to 1996, routine screening for whooping cough identified 399 patients with a calmodulin-dependent adenylate cyclase-positive test result and yielded 69 Bordetella pertussis isolates. None of the patients were fully vaccinated, and most were less than 6 months old. Analysis of total DNA by pulsed-field gel electrophoresis (PFGE) after XbaI, SpeI, or DraI macrorestriction yielded 19, 15, and 5 different patterns, respectively, whereas ribotyping failed to demonstrate any strain polymorphism. Discrimination among the isolates was improved by combining the PFGE profiles. Some patterns were more frequent, but the corresponding patients were not clearly epidemiologically related. The patterns for two strains obtained during a 3-month period from patients who were neighbors differed by the length of a single DNA fragment. These data strongly suggest that one type of isolate is widely spread throughout the world and is carried by individuals other than patients who develop a true illness. (+info)
Strain variation in adenovirus serotypes 4 and 7a causing acute respiratory disease.
(21/11802)
In order to determine the suitability of vaccine strains established in the 1960s for a new vaccine, a comprehensive study of strain variation of adenovirus serotype 4 (AV 4) and AV 7 was undertaken. A 1,500-bp region of the hexon gene containing the AV neutralization epitopes from prototype, vaccine, and community-acquired strains and from wild-type strains from military personnel that cause acute respiratory disease (ARD) was sequenced and analyzed. The whole hexon gene from prototype strains, vaccine strains, and selected isolates was sequenced. AV 7 and AV 7a were found to have distinct genotypes, and all vaccine and wild-type strains recovered from 1963 to 1997 had the AV 7a genotype. There was no significant strain variation in the neutralization epitopes of the AV 7a genotype over a 42-year period. The evolution of AV 4 was more complex, with continuous genetic drift punctuated by replacement with a new strain. The current strain of AV 4, which has been in circulation since 1995, is significantly different from the AV 4 prototype and the vaccine strains. Genetic differences were confirmed to be antigenic differences by neutralization tests, which define the new strain as an AV 4 variant. A type-specific PCR for AV 4, AV 7/7a, and AV 21 was developed, and this PCR facilitated the rapid identification of isolates from outbreaks of ARD. (+info)
The natural course of hepatitis C virus infection 18 years after an epidemic outbreak of non-A, non-B hepatitis in a plasmapheresis centre.
(22/11802)
BACKGROUND: The natural history of hepatitis C virus (HCV) infection is variable and factors determining the course of the illness are unclear. AIMS: To determine the natural course of HCV infection in a well characterised group of patients 18 years after an epidemic outbreak of non-A, non-B hepatitis at a plasmapheresis centre. METHODS: Between 1994 and 1996, 20 of 30 affected individuals were studied. HCV infection was confirmed using second and third generation ELISA test kits. HCV RNA was detected by a polymerase chain reaction (PCR) method and HCV genotyping was performed by analysing amplicons from the conserved 5'-non-translated region generated by nested PCR. Thirty two liver biopsies were carried out in 14 patients. RESULTS: HCV antibodies were detected in all subjects. Eighteen patients had abnormal liver enzymes and 17 were HCV RNA positive, all of whom were infected with genotype 1a. Ninety per cent of this cohort showed evidence of chronic HCV infection with 50% having progressive liver disease and 20% cirrhosis 18 years after acute onset of non-A, non-B hepatitis. Considerable variation in disease outcome occurred between individuals and no correlation with clinical features of the acute illness was found. CONCLUSIONS: Variability in the consequences of HCV infection in cases infected with the same virus suggests that host factors are important in determining disease outcome. The factors which determine differences in the natural history of the disease still remain to be elucidated. (+info)
What's driving an epidemic? The spread of syphilis along an interstate highway in rural North Carolina.
(23/11802)
OBJECTIVES: The purpose of this study was to determine whether county syphilis rates were increased along Interstate Highway 95 (I-95) in North Carolina during a recent epidemic. METHODS: Ecological data on syphilis cases demographic data, highway data, and drug activity data were used to conduct a cross-sectional and longitudinal study of North Carolina countries from 1985 to 1994. Crude and adjusted incidence rate ratios (IRRs) were determined by means of standard and longitudinal Poisson regression models adjusted for sociodemographic factors and drug use. RESULTS: Ten-year syphilis rates in I-95 counties greatly exceeded rates in non-I-95 counties (38 vs 16 cases per 100,000 persons) and remained higher after adjustment for race, age, sex, poverty, large cities, and drug activity (adjusted IRR = 2.05, 95% confidence interval [CI] = 1.84, 2.28). Syphilis rates were stable until 1989, when rates increased sharply in I-95 counties but remained stable in non-I-95 counties. Increased drug activity in I-95 counties preceded the rise in syphilis cases. CONCLUSIONS: A better understanding of the relationship between high-ways and the spread of sexually transmitted diseases may guide future prevention interventions. (+info)
A deviation bar chart for detecting dengue outbreaks in Puerto Rico.
(24/11802)
OBJECTIVES: A Centers for Disease Control and Prevention deviation bar chart (Statistical Software for Public Health Surveillance) and laboratory-based surveillance data were evaluated for their utility in detecting dengue outbreaks in Puerto Rico. METHODS: A significant increase in dengue incidence was defined as an excess of suspected cases of more than 2 SDs beyond the mean for all 4-week periods from April through June (the period of lowest seasonal incidence), 1989 through 1993. An outbreak was defined as a cumulative annual rate of reported dengue greater than 3 per 1000 population. RESULTS: Retrospective application of the system to 1994 data showed agreement with previous analyses. In 1995 and 1996, 36.4% and 27.3%, respectively, of municipalities with a significant increase in reports for 2 or more consecutive weeks before the first week of September had an outbreak, compared with 9.0% (in 1995, P = .042) and 6.0% (in 1996, P = .054) of towns without a significant increase. The system showed sensitivity near 40%, specificity near 89%, and accuracy in classifying municipalities near 84%. CONCLUSIONS: This method provides a statistically based, visually striking, specific, and timely signal for dengue control efforts. (+info)