Larry K. Pickering

Practice Guidelines for the Management of Infectious Diarrhea

The widening array of recognized enteric pathogens and the increasing demand for cost-containment sharpen the need for careful clinical and public health guidelines based on the best evidence currently available. Adequate fluid and electrolyte replacement and maintenance are key to managing diarrheal illnesses. Thorough clinical and epidemiological evaluation must define the severity and type of illness (e.g., febrile, hemorrhagic, nosocomial, persistent, or inflammatory), exposures (e.g., travel, ingestion of raw or undercooked meat, seafood, or milk products, contacts who are ill, day care or institutional exposure, recent antibiotic use), and whether the patient is immunocompromised, in order to direct the performance of selective diagnostic cultures, toxin testing, parasite studies, and the administration of antimicrobial therapy (the latter as for travelers diarrhea, shigellosis, and possibly Campylobacter jejuni enteritis). Increasing numbers of isolates resistant to antimicrobial agents and the risk of worsened illness (such as hemolytic uremic syndrome with Shiga toxin-producing Escherichia coli O157:H7) further complicate antimicrobial and antimotility drug use. Thus, prevention by avoidance of undercooked meat or seafood, avoidance of unpasteurized milk or soft cheese, and selected use of available typhoid vaccines for travelers to areas where typhoid is endemic are key to the control of infectious diarrhea.

Noroviruses bind to human ABO, Lewis, and secretor histo-blood group antigens: Identification of 4 distinct strain-specific patterns

We characterized the binding of 8 Noroviruses (NORs) to histo-blood group antigens (HBGAs) in human saliva using recombinant NOR (rNOR) capsid proteins. Among the 8 rNORs tested, 6 formed viruslike particles (VLPs) when the capsid proteins were expressed in insect cells, all of which revealed variable binding activities with saliva; the remaining 2 rNORs did not form VLPs, and the proteins did not bind, or bound weakly, to saliva. Four distinct binding patterns were associated with different histo-blood types, defined by Lewis, secretor, and ABO types. Three patterns (VA387, NV, and MOH) recognized secretors, and 1 pattern (VA207) recognized Lewis-positive nonsecretors. The 3 secretor-recognizing patterns were defined as A/B (MOH), A/O (NV), and A/B/O (VA387) binders. Oligosaccharides containing the Lewis and ABH antigenic epitopes were involved in binding. Our findings suggest that different strains of NORs may recognize different human HBGAs on intestinal epithelial cells as receptors for infection.

Genetic diversity among sapoviruses

Summary.Norovirus and Sapovirus are two genera of the family Caliciviridae that contain viruses that can cause acute gastroenteritis in humans. Noroviruses (NOR) are genetically highly diverse but limited studies of the genetic diversity of sapoviruses (SAP) have been reported. In this study we characterized twenty-five SAP detected in our laboratory from outbreaks or sporadic cases of acute gastroenteritis in children from different geographical locations and in adults involved in a cruise ship outbreak investigation and a nursing home outbreak. Based on significant differences of partial RNA polymerase sequences (278–286 nt), the 25 strains were grouped into 12 genetic clusters, including 9 potential new clusters. Extended sequence analysis of the capsid gene of selected strains representing five potential new clusters supported this grouping. Four strains (Hou7-1181/90, Mex340/90, Cruise ship/00 and Argentina39) had <84% amino acid (aa) identity to each other and to the published sequences in the GenBank. Mex14917/00 was almost identical to Stockholm/97/SE whose RNA polymerase sequence was unknown. Phylogenetic and distance analyses of the capsid region of the four new strains showed that Hou7-1181/90 and Argentina39 represent two new genogroups and Mex340/90 and Cruise ship/00 belong to two new clusters within the London/92 genogroup. Thus, based on the capsid sequences we propose to classify the currently known SAP into nine genetic clusters within five genogroups, including one genogroup that is represented by an animal calicivirus, the porcine enteric calicivirus (PEC).

Immunization Programs for Infants, Children, Adolescents, and Adults: Clinical Practice Guidelines by the Infectious Diseases Society of America

Evidence-based guidelines for immunization of infants, children, adolescents, and adults have been prepared by an Expert Panel of the Infectious Diseases Society of America (IDSA). These updated guidelines replace the previous immunization guidelines published in 2002. These guidelines are prepared for health care professionals who care for either immunocompetent or immunocompromised people of all ages. Since 2002, the capacity to prevent more infectious diseases has increased markedly for several reasons: new vaccines have been licensed (human papillomavirus vaccine; live, attenuated influenza vaccine; meningococcal conjugate vaccine; rotavirus vaccine; tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis [Tdap] vaccine; and zoster vaccine), new combination vaccines have become available (measles, mumps, rubella and varicella vaccine; tetanus, diphtheria, and pertussis and inactivated polio vaccine; and tetanus, diphtheria, and pertussis and inactivated polio/Haemophilus influenzae type b vaccine), hepatitis A vaccines are now recommended universally for young children, influenza vaccines are recommended annually for all children aged 6 months through 18 years and for adults aged > or = 50 years, and a second dose of varicella vaccine has been added to the routine childhood and adolescent immunization schedule. Many of these changes have resulted in expansion of the adolescent and adult immunization schedules. In addition, increased emphasis has been placed on removing barriers to immunization, eliminating racial/ethnic disparities, addressing vaccine safety issues, financing recommended vaccines, and immunizing specific groups, including health care providers, immunocompromised people, pregnant women, international travelers, and internationally adopted children. This document includes 46 standards that, if followed, should lead to optimal disease prevention through vaccination in multiple population groups while maintaining high levels of safety.

Lack of Association between Measles Virus Vaccine and Autism with Enteropathy: A Case-Control Study

BACKGROUND The presence of measles virus (MV) RNA in bowel tissue from children with autism spectrum disorders (ASD) and gastrointestinal (GI) disturbances was reported in 1998. Subsequent investigations found no associations between MV exposure and ASD but did not test for the presence of MV RNA in bowel or focus on children with ASD and GI disturbances. Failure to replicate the original study design may contribute to continued public concern with respect to the safety of the measles, mumps, and rubella (MMR) vaccine. METHODOLOGY/PRINCIPAL FINDINGS The objective of this case-control study was to determine whether children with GI disturbances and autism are more likely than children with GI disturbances alone to have MV RNA and/or inflammation in bowel tissues and if autism and/or GI episode onset relate temporally to receipt of MMR. The sample was an age-matched group of US children undergoing clinically-indicated ileocolonoscopy. Ileal and cecal tissues from 25 children with autism and GI disturbances and 13 children with GI disturbances alone (controls) were evaluated by real-time reverse transcription (RT)-PCR for presence of MV RNA in three laboratories blinded to diagnosis, including one wherein the original findings suggesting a link between MV and ASD were reported. The temporal order of onset of GI episodes and autism relative to timing of MMR administration was examined. We found no differences between case and control groups in the presence of MV RNA in ileum and cecum. Results were consistent across the three laboratory sites. GI symptom and autism onset were unrelated to MMR timing. Eighty-eight percent of ASD cases had behavioral regression. CONCLUSIONS/SIGNIFICANCE This study provides strong evidence against association of autism with persistent MV RNA in the GI tract or MMR exposure. Autism with GI disturbances is associated with elevated rates of regression in language or other skills and may represent an endophenotype distinct from other ASD.

Longitudinal study of occurrence of diarrheal disease in day care centers.

Sixty day care centers (DCC) randomly selected from 736 licensed child care facilities in Harris County (Houston), Texas were surveyed for the incidence of diarrhea by periodic visits and weekly telephone calls over two years. A total of 2,708 episodes of diarrhea were reported in 3,800 children under 6 years of age, and 84 cases occurred in center staff. Overall incidence was 0.44 episodes/person/year among children and 0.14 among staff. Attack rates among the 60 DCC ranged from none to 3.64 cases/year in each child. The incidence for children under 36 months of age was 17 times higher than for the older group. Characteristics of DCC associated with higher rates of disease among children were the presence of young, non-bowel trained children, staff who both diapered infants and prepared food on a regular basis, DCC for profit management, and DCC whose only guidelines were provided by the State. The socioeconomic burden associated with DCC disease, its transmission, and control is considerable and needs to be further addressed.

A prospective study of astrovirus diarrhea of infancy in Mexico City

AIM To describe the epidemiologic and clinical characteristics of astrovirus-associated diarrhea in a cohort of young children from a periurban community in Mexico City. METHODS From November, 1988, through December, 1991, a total of 214 children were enrolled in a longitudinal study of diarrhea and monitored from birth to 18 months of age. A stool specimen was collected during each episode of diarrhea. Specimens from a total of 510 diarrhea episodes were tested for astrovirus by enzyme immunoassay and examined for other enteric pathogens. The antigenic types of astrovirus were determined by a typing enzyme immunoassay. RESULTS Astrovirus was detected in 26 (5%) of 510 diarrhea episodes, with an incidence rate of 0.1 episode/child year; the highest rate was in children 13 to 18 months of age. Astrovirus-associated diarrhea was characterized by a median of 4 stools (range, 2 to 10) during the first 24 h, a median duration of 3 days (range, 1 to 21), vomiting (20%), and fever (7%). No cases of dehydration or repeat symptomatic infections were observed. Coinfection with another pathogen was detected in 11 of the 26 episodes (42%). Serotype 2 (35%) was most common, followed by serotypes 4 (15%), 3 (11%), and 1 and 5 (4% each); 31% were nontypable. Astrovirus-associated diarrhea was less severe, as measured by the number of stools (4.3 +/- 1.9), than diarrhea caused by rotavirus (7.1 +/- 2.8) or when coinfections occurred (5.5 +/- 1.6; P = 0.008). CONCLUSIONS Astrovirus was associated with 5% of the episodes of diarrhea in this cohort of young Mexican children and presented as a mild secretory diarrhea. Five predominant antigenic types were detected with type 2 being the most common.

Expert Review of the Evidence Base for Self-Therapy of Travelers' Diarrhea

The most frequent illness among people traveling from industrialized regions to developing countries is travelers’ diarrhea (TD). For all people entering areas known to pose a high risk for TD, medication should be included in the travel kit on trips, which can be taken for self‐therapy of resultant diarrheal illness. Drugs aimed at relief of symptoms, particularly loperamide, are the preferred standard treatment of TD by some professionals in Europe. Travel medicine experts in the United States and many in Europe feel that an antimicrobial agent that cures while shortening the duration of illness represents the mainstay of therapy. Loperamide combined with an appropriate antimicrobial agent will provide the most rapid relief of TD. In the following document, the authors used an evidence base when available to determine the strength and quality of evidence and when data were lacking, the panel of experts provided consensus opinion. Drugs used for symptomatic relief, including bismuth subsalicylate (BSS) and loperamide, decrease the number of unformed stools passed during a bout of TD but may not speed up illness recovery. The majority of authors of this document recommended that for all people traveling from low‐risk to high‐risk regions, one of the three antibacterial drugs should be transported with them for self‐treatment of diarrhea that occurs, given in respective order of development for TD therapy: a fluoroquinolone (ciprofloxacin or levofloxacin), rifaximin, or azithromycin. Azithromycin is preferred for treatment when diarrhea is complicated by dysentery (passage of grossly bloody stools) or by high fever and for use in children with TD. A number of experts would recommend additionally including loperamide in the travel kit for adults with TD as this may accelerate relief of the illness when used with an antimicrobial agent. An uncertain proportion of Europeans feel that it is sufficient to include loperamide alone …

Human Milk Contains Elements That Block Binding of Noroviruses to Human Histo—Blood Group Antigens in Saliva

Noroviruses (NVs) recognize human histo-blood group antigens (HBGAs) as receptors. We characterized the interaction of human milk samples with recombinant virus-like particles representing VA387, Norwalk, VA207, and MOH. Milk samples from 60 healthy women were tested for human HBGAs and for their ability to block the binding of NVs. Fifty-four women were secretors (Se+), and 6 were nonsecretors (Se-). No women had detectable A or B antigens in their milk samples. All 54 Se+ milk samples, but 0 of 6 Se- milk samples, blocked VA387 and Norwalk virus (Se+ binders) from binding to saliva samples. All 6 Lewis-positive Se- milk samples blocked binding to VA207, and variable blocking activities were exhibited by the Se+ milk samples. No milk samples blocked the binding of MOH to A and B antigens. Secretor and Lewis, but not A or B antigens, were present in human milk and were responsible for blocking NV binding to receptors and therefore are likely to be decoy receptors that protect breast-fed infants from NV infection.

Immune status of infants fed soy-based formulas with or without added nucleotides for 1 year: part 1: vaccine responses, and morbidity.

Background Immunologic development of soy-fed infants has not been extensively studied. Early studies of soy flour–based formulas showed decreased immunoglobulin production when soy protein intake was limited. However, there were no significant differences in rotavirus vaccine responses between breast-fed and soy protein isolate–based formula-fed infants. Nucleotides added to milk-based formula benefit infant immune status, but reports of the immunologic effects of adding nucleotides to soy-based formula are not available. This study evaluated immune status and morbidity of infants fed soy protein isolate formulas with and without added nucleotides for 1 year. Methods Newborn, term infants enrolled in a masked 12-month feeding trial were assigned randomly to groups fed soy formula with or without added nucleotides (n = 94, n = 92). A nonrandomized human milk/formula cohort (n = 81) was concurrently enrolled. Recommended immunizations were administered at 2, 4, and 6 months. Immune status was determined from antibody responses to Haemophilus influenzae type b, tetanus, diphtheria, and poliovirus vaccines at 6, 7, and 12 months. Parents and physicians reported morbidity data. Results All vaccine responses were within normal ranges. No response differences were observed between infants fed soy formula and those fed nucleotide-supplemented soy. However, antibody to H. influenzae type b at 7 and 12 months was higher in infants fed nucleotide-supplemented soy than in infants fed human milk/formula (P = 0.007, P = 0.008, respectively). Human milk/formula-fed infants had higher poliovirus neutralizing antibody at 12 months than did soy-fed infants (P = 0.016). Morbidity analyses showed that only physician-reported diarrhea was different among groups (groups fed human milk/formula had less diarrhea than did soy groups, P = 0.011). Conclusions Term infants fed soy protein isolate–based formulas have normal immune development as measured by antibody responses to childhood immunizations.