ABSTRACT
In order to characterize the association between county-level risk factors and the incidence of Cryptosporidium in the 2007 Iowa outbreak, we used generalized linear mixed models with the number of Cryptosporidium cases per county as the dependent variable. We employed a spatial power covariance structure, which assumed that the correlation between the numbers of cases in any two counties decreases as the distance between them increases. County population size was included in the model to adjust for population differences. Independent variables included the number of pools in specific pool categories (large, small, spa, wading, waterslide) and pool-owner classes (apartment, camp, country club or health club, hotel, municipal, school, other) as well as the proportion of residents aged <5 years. We found that increases in the number of bigger pools, pools with more heterogeneous mixing (municipal pools vs. country club or apartment pools), and pools catering to young children (wading pools) are associated with more cases at the county level.
Subject(s)
Cryptosporidiosis/epidemiology , Cryptosporidium/isolation & purification , Disease Outbreaks , Swimming Pools/standards , Water/parasitology , Adolescent , Adult , Aged , Aged, 80 and over , Child , Child, Preschool , Cryptosporidiosis/parasitology , Female , Humans , Infant , Iowa/epidemiology , Male , Middle Aged , Time Factors , Young AdultABSTRACT
To characterize the association between county-level risk factors and the incidence of mumps in the 2006 Iowa outbreak, we used generalized linear mixed models with the number of mumps cases per county as the dependent variable. To assess the impact of spring-break travel, we tested for differences in the proportions of mumps cases in three different age groups. In the final multivariable model, the proportion of Iowa's college students per county was positively associated (P<0.0001) with mumps cases, but the number of colleges was negatively associated with cases (P=0.0002). Thus, if the college students in a county were spread among more campuses, this was associated with fewer mumps cases. Finally, we found the proportion of mumps cases in both older and younger persons increased after 1 April (P=0.0029), suggesting that spring-break college travel was associated with the spread of mumps to other age groups.
Subject(s)
Mumps/epidemiology , Adolescent , Age Distribution , Disease Outbreaks , Humans , Iowa , Time Factors , Travel , Young AdultSubject(s)
Bacillus anthracis/metabolism , Chemistry Techniques, Analytical/methods , Chromatography, Gas/methods , Esters/chemistry , Fatty Acids/chemistry , Agar/chemistry , Calibration , Culture Media/pharmacology , Methylation , Models, Statistical , Quality Control , Glycine max/chemistry , Spores, Bacterial/metabolism , Time FactorsABSTRACT
Sexually transmitted diseases (STDs) are a major public health problem of the 1990s. In the pre-antibiotic era, these infections were often fatal. The 1960s saw an alteration in public attitudes toward sexual practices and a resultant increase in the incidence of STDs. Today, despite increased efforts in health education and the encouragement of "safe sex" practices, the incidence of STDs continues to rise. Infection control is complicated by the frequent lack of symptoms of many STDs. This article will discuss only the most common STDs in the United States. These include those caused by the organisms Neisseria gonorrhoeae, Herpes simplex virus, Chlamydia trachomatis, Treponema pallidum, Haemophilus ducreyi, and Hepatitis B virus.
Subject(s)
Cytodiagnosis/methods , Sexually Transmitted Diseases/epidemiology , Female , Humans , Infant, Newborn , Male , Pregnancy , Sexually Transmitted Diseases/diagnosisABSTRACT
Germination and outgrowth of spores of Streptomyces alboniger, Streptomyces scabies, and Streptomyces violaceus-ruber in the presence of intercalating dyes resulted in a high frequency (2 to 20%) of occurrence of aerial mycelium-negative (Amy-) isolates. Coincident with the appearance of the Amy- trait was the loss of several differentiated functions, including the characteristic pigments and earthy odor of the wild types. All S. alboniger, 27% of S. scabies, and 39% of the S. violaceus-ruber Amy- isolates were arginine auxotrophs. The missing enzyme step was identified as argininosuccinate synthetase by using a sensitive microassay for estimation of enzyme activity. The remainder of the S. scabies and S. violaceus-ruber isolates were prototrophs. In addition, S. alboniger Amy- isolates failed to produce or respond to the stimulator of aerial mycelium formation isolated from the wild type. The Amy- isolates did not revert to either Amy+ of Arg+. The lack of any detectable reversion, coupled with the high frequency of curing, supports the idea that a deletion of genetic material, possibly a plasmid, has occurred.
