Case-case analyses of cryptosporidiosis and giardiasis using routine national surveillance data in the United States - 2005-2015

Understanding endemic infectious disease risk factors through traditional epidemiological tools is challenging. Population-based case-control studies are costly and time-consuming. A case-case analyses using surveillance data addresses these limitations by using resources more efficiently. We conducted a case-case analyses using routine surveillance data reported by 16 U.S. states (2005-2015), wherein reported cases of salmonellosis were used as a comparison group to identify exposure associations with reported cases of cryptosporidiosis and giardiasis. Odds ratios adjusted for age and reporting state (aOR) and 95% confidence intervals (95% CI) were calculated. A total of 10 704 cryptosporidiosis cases, 17 544 giardiasis cases, and 106 351 salmonellosis cases were included in this analyses. When compared with cases of salmonellosis, exposure to treated recreational water (aOR 4.7, 95% CI 4.3-5.0) and livestock (aOR: 3.2; 95% CI: 2.9-3.5) were significantly associated with cryptosporidiosis and exposure to untreated drinking (aOR 4.1, 95% CI 3.6-4.7) and recreational water (aOR 4.1, 95% CI 3.7-4.5) were associated with giardiasis. Our analyses shows that routine surveillance data with standardised exposure information can be used to identify associations of interest for cryptosporidiosis and giardiasis.

Risk factors for sporadic Giardia infection in the USA: a case-control study in Colorado and Minnesota

Giardia duodenalis is the most common intestinal parasite of humans in the USA, but the risk factors for sporadic (non-outbreak) giardiasis are not well described. The Centers for Disease Control and Prevention and the Colorado and Minnesota public health departments conducted a case-control study to assess risk factors for sporadic giardiasis in the USA. Cases (N = 199) were patients with non-outbreak-associated laboratory-confirmed Giardia infection in Colorado and Minnesota, and controls (N = 381) were matched by age and site. Identified risk factors included international travel (aOR = 13.9; 95% CI 4.9-39.8), drinking water from a river, lake, stream, or spring (aOR = 6.5; 95% CI 2.0-20.6), swimming in a natural body of water (aOR = 3.3; 95% CI 1.5-7.0), male-male sexual behaviour (aOR = 45.7; 95% CI 5.8-362.0), having contact with children in diapers (aOR = 1.6; 95% CI 1.01-2.6), taking antibiotics (aOR = 2.5; 95% CI 1.2-5.0) and having a chronic gastrointestinal condition (aOR = 1.8; 95% CI 1.1-3.0). Eating raw produce was inversely associated with infection (aOR = 0.2; 95% CI 0.1-0.7). Our results highlight the diversity of risk factors for sporadic giardiasis and the importance of non-international-travel-associated risk factors, particularly those involving person-to-person transmission. Prevention measures should focus on reducing risks associated with diaper handling, sexual contact, swimming in untreated water, and drinking untreated water.

Prevalence and direct costs of emergency department visits and hospitalizations for selected diseases that can be transmitted by water, United States

National emergency department (ED) visit prevalence and costs for selected diseases that can be transmitted by water were estimated using large healthcare databases (acute otitis externa, campylobacteriosis, cryptosporidiosis, Escherichia coli infection, free-living ameba infection, giardiasis, hepatitis A virus (HAV) infection, Legionnaires' disease, nontuberculous mycobacterial (NTM) infection, Pseudomonas-related pneumonia or septicemia, salmonellosis, shigellosis, and vibriosis or cholera). An estimated 477,000 annual ED visits (95% CI: 459,000-494,000) were documented, with 21% (n = 101,000, 95% CI: 97,000-105,000) resulting in immediate hospital admission. The remaining 376,000 annual treat-and-release ED visits (95% CI: 361,000-390,000) resulted in $194 million in annual direct costs. Most treat-and-release ED visits (97%) and costs ($178 million/year) were associated with acute otitis externa. HAV ($5.5 million), NTM ($2.3 million), and salmonellosis ($2.2 million) were associated with next highest total costs. Cryptosporidiosis ($2,035), campylobacteriosis ($1,783), and NTM ($1,709) had the highest mean costs per treat-and-release ED visit. Overall, the annual hospitalization and treat-and-release ED visit costs associated with the selected diseases totaled $3.8 billion. As most of these diseases are not solely transmitted by water, an attribution process is needed as a next step to determine the proportion of these visits and costs attributable to waterborne transmission.

Mortality from selected diseases that can be transmitted by water - United States, 2003-2009

Diseases spread by water are caused by fecal-oral, contact, inhalation, or other routes, resulting in illnesses affecting multiple body systems. We selected 13 pathogens or syndromes implicated in waterborne disease outbreaks or other well-documented waterborne transmission (acute otitis externa, Campylobacter, Cryptosporidium, Escherichia coli (E. coli), free-living ameba, Giardia, Hepatitis A virus, Legionella (Legionnaires' disease), nontuberculous mycobacteria (NTM), Pseudomonas-related pneumonia or septicemia, Salmonella, Shigella, and Vibrio). We documented annual numbers of deaths in the United States associated with these infections using a combination of death certificate data, nationally representative hospital discharge data, and disease-specific surveillance systems (2003-2009). We documented 6,939 annual total deaths associated with the 13 infections; of these, 493 (7%) were caused by seven pathogens transmitted by the fecal-oral route. A total of 6,301 deaths (91%) were associated with infections from Pseudomonas, NTM, and Legionella, environmental pathogens that grow in water system biofilms. Biofilm-associated pathogens can cause illness following inhalation of aerosols or contact with contaminated water. These findings suggest that most mortality from these 13 selected infections in the United States does not result from classical fecal-oral transmission but rather from other transmission routes.

Is the corneal degradation in keratoconus caused by matrix-metalloproteinases?

The thinning of the cornea that occurs in keratoconus has been well described; however, the mechanism of tissue degradation remains unknown. Elevated proteinase activity is one possibility and approximately 20 publications over the last 20 years have addressed this hypothesis. Early studies reported increased collagenase and gelatinase activities in the medium of keratoconus corneal cultures. After the characterization of the matrix metalloproteinase (MMP) enzymes, studies focused on the expression of specific MMPs, in particular the gelatinases, MMP-2 and MMP-9. Matrix metalloproteinase-2 was found to be the major MMP of the cornea and was constitutively produced in normal tissue, whereas MMP-9 expression was induced by various stimuli, including phorbol esters and even tissue culturing. These studies suggested that there were no differences in the amounts or states of activation of MMP between normal and keratoconus corneas, although the amounts of some proteinase inhibitors, including tissue inhibitors of metalloproteinases, alpha-1-proteinase inhibitor and alpha-2-macroglobulin, were decreased in keratoconus. Most recently, the lysosomal proteinases, cathepsin B and cathepsin G were reported to be elevated in keratoconus corneas, and it is possible that it was cathepsin activity, not MMP activity, that was measured in some early studies. Nevertheless, there are now about 20 human MMPs identified and it is possible that some of these, other than the well known collagenase (MMP-1) and gelatinases (MMP-2 and MMP-9), could be implicated in the pathology of keratoconus. Studies have begun to address more recently described MMPs and it has been reported that the membrane-bound MT1-MMP (MMP-14), which activates latent MMP-2, was found to have increased expression in keratoconus corneas, whereas the stromelysins, MMP-3 and MMP-10, were not.

Expression of membrane-type 1 matrix metalloproteinase (MT1-MMP) and MMP-2 in normal and keratoconus corneas

PURPOSE

To determine whether MT1-MMP and MMP-2 are expressed in normal and keratoconic corneas, and to investigate the ability of MT1-MMP, expressed on cultured keratocytes after stimulation with concanavalin A, to activate pro-gelatinase A (pro-MMP 2).

METHODS

Specimens of keratoconus corneas (n = 20), removed at corneal transplantation, were obtained from pathology archives, sections were cut, and were stained with an antibody to MT1-MMP, using peroxidase immunohistochemistry. Eye banked corneas served as controls (n = 14). Normal human keratocyte cultures were initiated from eye bank corneas, and after stimulation with con A, MMPs in the media were examined using gelatin zymography and immunoblotting, and MT1-MMP expression was analysed by flow cytometry and immunoblotting.

RESULTS

All corneas showed some expression of MT1-MMP and MMP-2, although the degree of staining varied greatly. The MMPs were present in the epithelium, endothelium and stroma. Expression of MT1-MMP, but not MMP-2, in the epithelium and stroma, was significantly elevated in keratoconus, compared to normal corneas. In vitro, keratocytes stimulated with con A expressed MT1-MMP and produced active MMP-2, detected by zymography. These responses to con A were concentration-dependent and MT1-MMP expression and MMP-2 activation correlated significantly (p = 0.0003) In addition, MMP inhibitors abolished MMP-2 activation, providing further evidence that MT1-MMP activated MMP-2.

CONCLUSION

The observation that MT1-MMP expression may be up-regulated in keratoconus corneas, taken together with the demonstration that human corneal cells can express this enzyme, which in turn can activate latent MMP-2, provide evidence for a possible role for MT1-MMP in the pathogenesis of keratoconus.

Reduction of the immunogenicity of fetal mouse pancreas allografts by organ culture in 90 percent oxygen

BALB/c female streptozotocin-diabetic mice were transplanted under the left kidney capsule with syngeneic or allogeneic CBA 17-day fetal pancreases that had been organ-cultured for 23 days. Two isografted groups received a single graft per recipient, cultured normally (90% air, 10% CO2), or in an oxygen-rich atmosphere (90% O2, 10% CO2): 13/14 and 12/13 respectively became normoglycemic. The 3rd and 4th groups were transplanted each with 1 and 3 allogeneic fetal pancreases per recipient, which had been cultured in 90% O2: 5/12 and 2/13 mice respectively had surviving allografts after 104 days, and 2/5 of the former and both of the latter had become normoglycemic. Five out of the seven surviving allografts contained foci of infiltrating lymphocytes. After removal of the kidneys containing the grafts, surviving mice were retransplanted under the right kidney capsule, each with 2 CBA fetal pancreases which had been cultured for only 4 days under normal conditions--hence they were fully immunogenic. Rejection of the secondary allografts was delayed in the long-term, primary allograft acceptors, suggesting that a degree of tolerance had developed. This study demonstrates that it is possible for a single, cultured fetal pancreas to survive indefinitely and reverse diabetes after transplantation to a fully allogeneic, nonimmunosuppressed recipient.

Detrimental effect of high medium glucose concentration on subsequent endocrine function of transplanted organ-cultured foetal mouse pancreas

Single 17-day foetal mouse pancreases, cultured for 15 days in RPMI 1640 or DME containing either 1 or 4 g/l glucose, were grafted under the kidney capsule of syngeneic mice made diabetic with Streptozotocin. Islets cultured in media containing 1 g/l glucose secreted less insulin in vitro than those grown in media containing 4 g/l glucose. After transplantation, the blood glucose levels of diabetic mice grafted with islets grown in media containing 1 g/l glucose decreased to normal limits, whereas mice grafted with islets grown in media with 4 g/l glucose never became normoglycaemic. Histologically, grafts of tissue from high glucose cultures were smaller and had less well organized islet tissue than grafts from tissue maintained in physiological glucose concentrations. Islets cultured in DME secreted more insulin in vitro than those cultured in RPMI 1640, but the type of culture medium had no significant effect on subsequent graft function. These data support the concept that chronic exposure of foetal islets to high glucose concentration may be deleterious to their subsequent function as grafts despite the fact that they secrete more insulin in vitro.