Evidence that Cryptosporidium parvum Populations Are Panmictic and Unstructured in the Upper Midwest of the United States

Cryptosporidium parvum is a zoonotic protozoan parasite that causes cryptosporidiosis, an infectious diarrheal disease primarily affecting humans and neonatal ruminants. Understanding the transmission dynamics of C. parvum, particularly the specific contributions of zoonotic and anthroponotic transmission, is critical to the control of this pathogen. This study used a population genetics approach to better understand the transmission of C. parvum in the Upper Midwest United States. A total of 254 C. parvum isolates from cases of human cryptosporidiosis in Minnesota and Wisconsin and diarrheic calves in Minnesota, Wisconsin, and North Dakota were genotyped at eight polymorphic loci. Isolates with a complete profile from all eight loci (n = 212) were used to derive a multilocus genotype (MLT), which was used in population genetic analyses. Among the 94 MLTs identified, 60 were represented by a single isolate. Approximately 20% of isolates belonged to MLT 2, a group that included both human and cattle isolates. Population analyses revealed a predominantly panmictic population with no apparent geographic or host substructuring.     

Vitamin D (25OHD) Serum Seasonality in the United States

Background

Vitamin D is an important micronutrient for health. Hypovitaminosis D is thought to play a role in the seasonality of a number of diseases and adverse health conditions. To refine hypotheses about the links between vitamin D and seasonal diseases, good estimates of the cyclicality of serum vitamin D are necessary.

Objectives

The objective of this study is to describe quantitatively the cyclicality of 25-hydroxyvitamin D (25OHD) in the United States. We provide a statistical analysis with weekly time resolution, in comparison to the quarterly (winter/spring/summer/fall) estimates already in the literature.

Methods

We analyzed time series data on 25OHD, spanning 287 consecutive weeks. The pooled data set comes from 3.44 million serum samples from the United States. We statistically analyzed the proportion of sera that were vitamin D sufficient, defined as 25OHD ng/mL, as a function of date.

Results

In the United States, serum 25OHD follows a lagged pattern relative to the astronomical seasons, peaking in late summer (August) and troughing in late winter (February). Airmass, which is a function of solar altitude, fits the 25OHD data very well when lagged by 8 weeks.

Conclusions

Serum vitamin D levels can be modeled as a function of date, working through a double-log transformation of minimal solar airmass (easily calculated from solar altitude, retrievable from an online solar altitude/azimuth table).     

Plants of the Northeastern United States that produce cyanogenic compounds

We have surveyed the distribution of plants in the northeastern United States that contain cyanogenic compounds. Approximately 200 species of plants from 45 families are known to contain compounds capable of liberating hydrogen cyanide upon hydrolysis. These are primarily found in the Gramineae, Ranunculaceae and the Rosaceae. The chemical structures compounds of the cyanogens have been studied in only a small number of the species included, and investigation of the biology and chemistry of these plants should prove especially profitable.     

Evidence of susceptibility to morbillivirus infection in cetaceans from the United States

Cetacean morbilliviruses (CeMV) are viruses that can cause mass mortalities among various odontocete species. In this study levels of “herd” immunity in cetaceans from the U.S. coast are described from the distribution and prevalence of antibodies against morbilliviruses. Neutralizing antibody titers against dolphin morbillivirus (DMV), porpoise morbillivirus (PMV), phocine distemper (PDV), and canine distemper viruses (CDV) were measured. Positive samples had higher titers against the CeMV than against the other morbilliviruses tested, indicating that although PDV or CDV can be used to investigate exposure their use may result in a higher false negative rate. The results suggest that morbillivirus did not persist in coastal populations of bottlenose dolphins (Tursiops truncatus) after the major outbreaks that occurred in the 1980s and 1990s. Bottlenose dolphins from Beaufort, North Carolina; St. Joseph Bay, Florida; and Cape May, New Jersey had anti‐DMV seroprevalences ranging from between 15% and 33% but those from Charleston, South Carolina and Sarasota Bay, Florida, sampled in recent years were largely negative. These latter groups are therefore now vulnerable to infection and could experience high mortality if exposed to CeMV. Sero‐surveys of this kind are therefore vital for assessing the risk of new and recurring viral outbreaks in coastal cetaceans.     

Evidence of arthropod-plant interactions in the Upper Triassic of the southwestern United States

Leaves from the Upper Triassic Chinle Formation in the southwestern United States show evi dence of having provided nourishment and shelter for several different types of arthropods. This evidence consists of three or four morphotypes of feeding traces and a well-defined type of gall. The feeding traces occur on the pinnules of the filicalean fern Cynepteris lasiophora (Daugherty) Ash and the pinnae of the bennettitalean leaf Zamites sp. and Marcouia neuropter-oides Ash, a gymnosperm leaf of uncertain relationships. Typically, the feeding traces are only a few mm in length and have smooth, continuous margins which are often bordered by a nar-row dark band that represents reaction tissue formed in response to feeding. Presence of this tissue indicates that the leaves continued to function after the damage occurred and while they were still attached to the parent plant. The relatively small size and shape of the feeding traces shows that they were most likely produced by grazing insects. Gall-like swellings are found on the leaves of Dechellyia gormanii Ash, another gymnosperm fossil of uncertain relationships. The swellings are well defined, round to deltoid in outline, and bulbous. Typically, only one such swelling occurs on a leaf. Leaves that have these swellings are often distorted or terminate abruptly at the disturbance, particularly if the structure extends over the edge of the leaf. The swellings resemble galls induced on leaves of certain modern plants by eriophyid mites and apparently are either prosoplasmatic histioid pit galls or pouch galls.     

Diverse Burkholderia Species Isolated from Soils in the Southern United States with No Evidence of B. pseudomallei

The global distribution of the soil-dwelling bacterium Burkholderia pseudomallei, causative agent of melioidosis, is poorly understood. We used established culturing methods developed for B. pseudomallei to isolate Burkholderia species from soil collected at 18 sampling sites in three states in the southern United States (Arizona (n = 4), Florida (n = 7), and Louisiana (n = 7)). Using multi-locus sequence typing (MLST) of seven genes, we identified 35 Burkholderia isolates from these soil samples. All species belonged to the B. cepacia complex (Bcc), including B. cenocepacia, B. cepacia, B. contaminans, B. diffusa, B. metallica, B. seminalis, B. vietnamiensis and two unnamed members of the Bcc. The MLST analysis provided a high level of resolution among and within these species. Despite previous clinical cases within the U.S. involving B. pseudomallei and its close phylogenetic relatives, we did not isolate any of these taxa. The Bcc contains a number of opportunistic pathogens that cause infections in cystic fibrosis patients. Interestingly, we found that B. vietnamiensis was present in soil from all three states, suggesting it may be a common component in southern U.S. soils. Most of the Burkholderia isolates collected in this study were from Florida (30/35; 86%), which may be due to the combination of relatively moist, sandy, and acidic soils found there compared to the other two states. We also investigated one MLST gene, recA, for its ability to identify species within Burkholderia. A 365bp fragment of recA recovered nearly the same species-level identification as MLST, thus demonstrating its cost effective utility when conducting environmental surveys for Burkholderia. Although we did not find B. pseudomallei, our findings document that other diverse Burkholderia species are present in soils in the southern United States.     

Environmental influences on the productivity of three desert succulents in the south-western United States

Abstract Net CO₂ uptake over 24 h periods for shoots of Agave deserti, Ferocactus acanthodes, and Opuntia ficus-indica was measured under the ranges of water status, air temperature, and photo-synthetically active radiation (PAR) that occur in the south-western U.S.A. An environmental productivity index (EPI) was constructed indicating the overall influence of these three factors on net CO₂ uptake. Using growth chambers whose conditions were changed monthly to simulate the environmental conditions at a field site, the observed shoot dry weight increases per unit surface area changed in concert with monthly changes in EPI. The observed dry weight gain of the shoot was 17–19% lower than the predicted shoot net CO₂ uptake, which could be accounted for by carbon diversion to the roots. Mean monthly EPI was also predicted for 21 sites in the south-western U.S.A. All three species had low EPIs in the Colorado River basin, which has low annual rainfall and high summer temperatures, and in the north-central part of the region, which has low temperatures and low PAR during winter when water is available. The two native species, A. deserti and F. acanthodes, had high EPIs beyond their range in coastal southern California, where competition by other vegetation for PAR may limit net CO₂ uptake. Such regions as well as south-central California and south-central Arizona had high EPIs for all three species, indicating that these areas would be appropriate for the cultivation of O. ficus-indica.     

Phylogenetic affiliation of the bacteria that constitute phototrophic consortia

The phylogenetic affiliation of epibionts occurring in three morphologically distinct types of green-colored phototrophic consortia was investigated. Intact consortia of the types "Chlorochromatium aggregatum", "C. glebulum", and a third previously undescribed type, tentatively named "C. magnum" were mechanically separated from accompanying bacteria by either micromanipulation or by chemotactic accumulation in sulfide-containing capillaries. A 540-base-pair-long fragment of the 16S rRNA gene of the epibionts was amplified employing PCR primers specific for green sulfur bacteria. DNA fragments were separated by denaturing gradient gel electrophoresis and subsequently sequenced. The results of this phylogenetic analysis indicated that the symbiotic epibionts, together with only a few free-living strains, form a cluster within the green sulfur bacterial radiation which is only distantly related to the majority of known representatives of this phylum. Consortia with identical morphology but different origin exhibited significant differences in their partial 16S rRNA gene sequences, which could be confirmed by analysis of the 16S rRNA secondary structure. The phylogenetic affiliation of the chemotrophic central rod-shaped bacterium of "C. aggregatum" and "C. magnum" was analyzed by fluorescent in situ hybridization. According to our results and contrary to earlier assumptions, the central bacterium is a member of the beta-subgroup of the Proteobacteria.     

The racial disparity in breast cancer mortality in the 25 largest cities in the United States

Introduction: Although the racial disparity in breast cancer mortality is widely discussed there are no studies that analyze this phenomenon at the city level. Methods: We used national death files, abstracting those cases for which the cause was malignant neoplasm of the breast (ICD-10 = C50) for the numerators and American Community Survey data for the denominators. The 25 largest cities in the US were the units of analysis. Non-Hispanic Black:non-Hispanic White rate ratios (RRs) were calculated, along with their confidence intervals, as measures of the racial disparity. Seven ecological (city-level) variables were examined as possible correlates. Results: Almost all the NHB rates were greater than almost all the NHW rates. All but 3 of the RRs (range 0.78–2.09; median = 1.44) were >1, 13 of them significantly so. None of the RRs < 1 were significant. From among the 7 potential correlates, only median household income (r = ?0.43, p = 0.037) and a measure of segregation (r = 0.42, r = 0.039) were significantly related to the RR. Conclusion: This is the first study that we have been able to locate which examines city-level racial disparities in breast cancer mortality. The results are of concern for several cities and for the field in general. A strategy for reducing this disparity in Chicago is in place and may serve as a model for other cities wanting to initiate a similar process. Clearly it is time to take action.     

Breastfeeding in the United States

The breastfeeding of US infants born in 1974-76 is analyzed using data form the 1976 National Survey of Family Growth. Life table estimates of the proportion of children breastfed by duration since birth and mean breastfeeding durations are presented. The life tables reported are constructed by standard cohort table methods. To compare life tables for children of mothers in various attribute categories, generalised Wilcoxon tests are used, together with multiple classification analysis for continuation at select durations. Variables considered include mother's age at the birth, ethnicity, educational level, education by ethnicity, region of residence and the child's birth order. Findings are restricted to infants remaining with their mothers for at least 2 months following delivery and surviving as of the survey date in January-September 1976. It is found that the proportion of infants breastfed was increasing rapidly, with the highest rates found among white (39%), college-educated (56%), western (56%) mothers and lowest rates among black mothers (17%) mothers with less than a high school education (19%) and mothers living in the south (24%). By age, the highest proportions are mothers at ages 25-29 (44%), followed closely by the mothers under 25 (29%). The proportions breastfeeding were also found to be higher in urban than in rural areas (38% vs. 28%) and higher at parities 1-2 (29%). A multiple classification analysis of the factors most strongly influencing breastfeeding in 1975 shows educational level to be the strongest single predictor of breastfeeding, followed by western residence and white ethnicity. Age effects were found to correlate strongly with education. Reviewing 1971-1981 changes, the proportion of mothers with less than a college education who breastfed their children increased from 19% to 51% over the decade, while the proportion among college-educated mothers rose from 42% to 74%. For children who were breastfed, the median duration was about 4.5 months. The mean was 5.5 months, with a range from about 3.0 months among black mothers with less than a high school education, to 6.0 months among college-educated white women. The nationwide changes in breastfeeding patterns and duration may confer modest health benefits on current generations of youngsters, although not benefits that are easily measured, since human milk substitutes are routinely subjected to rigourous testing for nutritional adequacy.