Toxins and virulence factors of enterotoxigenic Escherichia coli associated with strains isolated from indigenous children and international visitors to a rural community in Guatemala.

Diarrhoea remains a common cause of illness in Guatemala, with children suffering most frequently from the disease. This study directly compared the frequency, enterotoxin, and colonization factor (CF) profiles of enterotoxigenic Escherichia coli (ETEC) strains isolated from children living in a rural community in Guatemala and from Western visitors to the same location during the same seasons, using similar detection methodologies. We found that ETEC accounted for 26% of severe cases of diarrhoea in children requiring hospitalization, 15% of diarrhoea in the community, and 29% of travellers' diarrhoea in visitors staying ⩾2 weeks. The toxin and CF patterns of the ETEC strains isolated from both groups differed significantly (P < 0·0005) as determined by χ 2 = 60·39 for CFs and χ 2 = 35 for toxins, while ETEC phenotypes found in Guatemalan children were comparable to those found in children from other areas of the world.

Oral delivery of Hyperimmune bovine serum antibodies against CS6-expressing enterotoxigenic Escherichia coli as a prophylactic against diarrhea.

BACKGROUND: . Oral administration of bovine antibodies active against enterotoxigenic Escherichia coli (ETEC) have demonstrated safety and efficacy against diarrhea in human challenge trials. The efficacy of bovine serum immunoglobulins (BSIgG) against recombinant colonization factor CS6 or whole cell ETEC strain B7A was assessed against challenge with the CS6-expressing B7A. METHODS: . This was a randomized, double-blind, placebo-controlled trial in which healthy adults received oral hyperimmune BSIgG anti-CS6, anti-B7A whole cell killed or non-hyperimmune BSIgG (placebo) in a 1:1:1 ratio then challenged with ETEC B7A. Two days pre-challenge, volunteers began a thrice daily, seven day course of immunoprophylaxis. On day 3, subjects received 1 × 1010 CFUs of B7A. Subjects were observed for safety and the primary endpoint of moderate-severe diarrhea (MSD). RESULTS: . A total of 59 volunteers received product and underwent ETEC challenge. The BSIgG products were well-tolerated across all subjects. Upon challenge, 14/20 (70%) placebo recipients developed MSD, compared to 12/19 (63%; p = .74) receiving anti-CS6 BSIgG and 7/20 (35%; p = .06) receiving anti-B7A BSIgG. Immune responses to the ETEC infection were modest across all groups. CONCLUSIONS: . Bovine-derived serum antibodies appear safe and well tolerated. Antibodies derived from cattle immunized with whole cell B7A provided 50% protection against MSD following B7A challenge; however, no protection was observed in subjects receiving serum antibodies targeting CS6. The lack of observed efficacy in this group may be due to low CS6 surface expression on B7A, the high dose challenge inoculum and/or the use of serum derived antibodies versus colostrum-derived antibodies.

Response of the somatotropic axis to alterations in feed intake of channel catfish (Ictaluruspunctatus).

To better understand the effects of reduced feeding frequency on the GH-IGF-I axis, channel catfish (Ictaluruspunctatus), were either fed (Fed control, commercial diet fed daily), fed every other day (FEOD, commercial diet fed every other day), or not fed (Unfed, no feed). Pituitary GH mRNA increased whereas hepatic growth hormone receptor (GHR), IGF-I mRNA, and plasma IGF-I decreased in the FEOD and Unfed fish (P<0.05). In another study, fish were either continually fed (Fed) or fasted and then re-fed (Restricted) to examine the physiological regulation of somatostatin-14 (SS-14) and SS-22 mRNA. Fasting increased (P<0.05) levels of SS-14 mRNA in the hypothalamus and pancreatic islets (Brockmann bodies) at d 30 while re-feeding decreased SS-14 mRNA to control values in all tissues examined by d 45. Fasting had no effect on levels of SS-22 mRNA in the pancreatic islets whereas SS-22 mRNA was not detected in the stomach or hypothalamus. The results demonstrate that feeding every other day has similar negative impacts on components of the GH-IGF-I axis as fasting. The observed increase in SS-14 mRNA in the hypothalamus and pancreatic islets suggests a role for SS-14 in modulating the GH-IGF-I axis in channel catfish.

Gastric lavage: a simple method to obtain IgA-rich intestinal secretions from the rabbit.

A lavage procedure was developed to obtain intestinal secretions from rabbits. The procedure facilitated the repeated monitoring of the intestinal IgA immune response of these animals to enteric infection with Campylobacter jejuni. This non-invasive technique was easily performed, reproducible and yielded consistent levels of IgA from rabbit intestinal secretions. It is anticipated that this procedure will aid in the study of the intestinal immune response of rabbits to other enteric pathogens.

Empirical treatment of Shigella dysentery with trimethoprim: five-day course vs. single dose.

Fifty-three adults hospitalized with Shigella dysentery were empirically treated with trimethoprim (200 mg) twice/day for 5 days, a single dose of trimethoprim (600 mg), or placebo in a randomized double-blind trial. During the first 24 hr of therapy, there was a reduction in the number of stools in 18/21 (86%) of patients treated with the 5-day regimen (trimethoprim-5) and 13/15 (87%) of patients treated with a single dose (trimethoprim-1), compared with 7/17 (41%) of the placebo group (P less than 0.025, both comparisons). The mean number of stools passed in the first 24 hr of therapy was 10.6, 10.8, and 21.3 stools in the trimethoprim-5, trimethoprim-1, and placebo groups, respectively. The mean (+/- SD) change in number of stools from baseline among treated patients during the first 24 hr was -4.9 (6.6) and -6.3 (6.3) for the trimethoprim-5 and trimethoprim-1 groups, respectively, compared with an increase of +2.4 (14.8) for the placebo group. There was a clinical failure at 48 hr in 9% of the trimethoprim-5 patients and 13% of trimethoprim-1 patients compared with 70% of placebo patients (P less than 0.005, both comparisons). Although we were unable to demonstrate a difference in efficacy between the two dosage schedules of trimethoprim, we conclude that both treatment regimens are effective for the treatment of Shigella dysentery.

Prevention of scrub typhus. Prophylactic administration of doxycycline in a randomized double blind trial.

We conducted a prospective randomized double blind study on the effects of doxycycline as a prophylactic antibiotic against scrub typhus. A total of 1,125 military subjects was followed for periods as long as 5 months of exposure in a hyperendemic focus in the Pescadores Islands of Taiwan. Oral 200 mg doses of doxycycline (Vibramycin) or placebo were given once each week throughout the trial. The incidence rate of scrub typhus in the placebo group was 2.5 times greater than that of the group taking doxycycline (P = 0.11). When subjects who failed to comply with scheduled administration of doxycycline were removed from the analysis, the incidence rate of scrub typhus in the control group was five times greater than that in the drug group (P = 0.04). The rates of infection with Rickettsia tsutsugamushi and of sick call reports were the same in experimental and control groups. The drug was well tolerated in pretrial tests and complaints were negligible during the conduct of the trial. Doxycycline appears to be an excellent antibiotic for the prevention of scrub typhus among personnel exposed to high risk of infection with R. tsutsugamushi.

Pre-exposure anti-Campylobacter jejuni immunoglobulin a levels associated with reduced risk of Campylobacter diarrhea in adults traveling to Thailand.

Diarrhea history questionnaires were administered to 369 U.S. military volunteers before and after deployment to Thailand. Additionally, blood samples obtained from a subset of 221 volunteers 1-3 weeks previously and 3-4 weeks after their deployment were tested by enzyme-linked immunosorbent assay for immunoglobulin A to Campylobacter jejuni. Stool samples from personnel (including volunteers) contracting diarrhea in Thailand were cultured for enteric pathogens. Overall, 35.2% (130 of 369) of questionnaire respondents reported one or more diarrhea episodes during their trip. Volunteers with pretravel anti-C. jejuni reciprocal titers < or = 450 were 1.6 times as likely to have had diarrhea during their stay in Thailand compared with those with pretravel titers > 450 (39.7% versus 25.3%; P = 0.05). The symptomatic seroconversion, or attributable Campylobacter diarrhea attack rate, for the 1-month exercise was 12.7% (28 of 221). The symptomatic seroconversion rate in nonimmune (titer < or = 450) volunteers was 17.1%, whereas that in immune volunteers was only 4.0% (P = 0.002). Campylobacter jejuni or C. coli were recovered from 32.9% (56 of 170) of stool samples cultured and were the most commonly identified enteropathogens. Campylobacter diarrhea was associated with elevated temperatures, fecal red cells, and fecal white blood cells. The results of this study show that Campylobacter continues to represent a significant health threat to Western travelers to Thailand, but many of these travelers have preexisting Campylobacter immunity that protects them from clinically significant Campylobacter enteritis.

Short-course norfloxacin and trimethoprim-sulfamethoxazole treatment of shigellosis and salmonellosis in Egypt.

In a double-blind clinical study, 109 adult Egyptian patients infected with Shigella spp. and 45 infected with Salmonella spp. were randomly assigned to three treatment groups: 1) norfloxacin in a single 800-mg dose, 2) norfloxacin, 400 mg twice a day for three days, and 3) trimethoprim (160 mg)-sulfamethoxazole (800 mg) (TMP-SMX), twice a day for three days. Among Shigella-infected patients, diarrheal symptoms had resolved in 86-97% and bacteriologic failure (repeat positive stool culture) occurred in only two patients five days after the start of the three treatment regimens. Among Salmonella-infected patients, diarrheal symptoms had resolved in 76-82% of patients and bacteriologic failure was common (18-36%) five days after the start of therapy. These data indicate that short-course therapy with either norfloxacin or TMP-SMX can be effectively used to treat shigellosis in adults in developing countries. However, for uncomplicated Salmonella spp. infection, short-course therapy with norfloxacin and TMP-SMX may not lead to a rapid resolution of symptoms or consistently eliminate this enteropathogen.

Evaluation of febrile patients in Port Sudan, Sudan: isolation of dengue virus.

One hundred consecutive patients admitted to the Port Sudan Hospital with a temperature greater than or equal to 100 degrees F were evaluated. Enteric fever was diagnosed in 19 patients and malaria in 13. Virologic studies identified 21 cases of dengue infection. One dengue 1 and 17 dengue 2 infections were diagnosed by viral isolation. Three untyped dengue infections were identified serologically. The clinical presentation and course of patients infected with dengue virus were most consistent with classic dengue fever. There was no evidence of hemorrhagic phenomena or shock in any of the dengue-infected patients. Both dengue 1 and 2 must be considered causes of acute fever in East Africa.

Etiology of acute diarrhea among United States military personnel deployed to South America and west Africa.

A study of acute diarrhea was conducted from 1985 to 1987 among U.S. military personnel participating in routine shipboard exercises in South America and West Africa and ground troops deployed to coastal Ecuador. An enteropathogen was identified in 146 (51%) of 289 acute cases of diarrhea. Enterotoxigenic Escherichia coli, found in 50 (17%) patients with diarrhea, was the most commonly identified enteropathogen. Viral enteropathogens were also found in a high percentage of acute cases of diarrhea: rotavirus was detected in 11% of the patients and Norwalk virus infection in 10%. Most enteric pathogens were acquired in equal frequencies in South America and West Africa, except for rotavirus infection which was identified more often in West Africa and enteroaggregative E. coli infection which was identified more often in South America. Bacterial enteropathogens were frequently resistant to trimethoprim/sulfamethoxazole, but no resistance to quinolone drugs was observed, indicating that quinolone drugs have become important agents for the treatment of diarrhea in South America and West Africa.

Diarrhoeal disease: current concepts and future challenges. Epidemiology of diarrhoeal diseases in developed countries.

Diarrhoeal diseases are a common problem in industrialized countries, resulting in appreciable morbidity and mortality. While the total burden of these illnesses is much less than that in developing countries, the same basic disease risk factors influence transmission. This article reviews selected environmental, host and pathogen-specific factors which shape the epidemiology of infectious diarrhoea in developed countries. The effective adaptation of techniques from molecular biology, such as plasmid analysis, deoxyribonucleic acid hybridization, and the polymerase chain reaction, to studies of diarrhoeal disease epidemiology is also discussed.

Population indices of chiggers (Leptotrombidium deliense) and incidence of scrub typhus in Chinese military personnel, Pescadores Islands of Taiwan, 1976-77.

Larval Leptotrombidium deliense were recovered from live-trapped Suncus murinus, Rattus rattus and R. norvegicus captured in the Pescadores Islands of Taiwan during 1976 and 1977. Weekly and monthly indices of chigger infestation expressed as a percentage of hosts infested and the number of chiggers per host for S. murinus and Rattus spp. were calculated. Close correlations were observed between monthly indices of L. deliense measured for S. murinus and Rattus spp. and the number of laboratory-confirmed cases of scrub typhus per month. Weekly indices from S. murinus correlated more closely with number of cases than did weekly indices from Rattus spp. The critical level of chigger infestation necessary for a single case of scrub typhus in a month was estimated at 0.69 chigger per S. murinus and 0.68 chigger per Rattus spp. The weekly index of chigger infestation necessary for a single case of scrub typhus during a week was calculated at 0.47 chiggers per shrew. Critical levels of chigger infestations expressed as percentages of hosts infested were not calculated.

Antibodies against murine typhyus in sera from Indonesians.

A sero-epidemiological study of human CF and indirect immunofluorescence antibodies against murine typhus was conducted in Indonesia. Antibody prevalences ranged from 10% to 20% in sera of Indonesians from Java and Sumatra to less than 2% in sera from islands east of Java.

Epidemiological and serological study of scrub typhus among Chinese military in the Pescadores islands of Taiwan.

An outbreak of 69 cases of scrub typhus occurred among Chinese military personnel stationed in the Pescadores Islands, Taiwan Province, Republic of China between May and November 1975. A retrospective epidemiological study of this outbreak indicated that military personnel over 40 were more likely to have scrub typhus than those under 40. High risk groups included the Garrison Force (home guard), anti-aircraft gunners and infantry and armoured units stationed at Hsing-jen. The onset of symptoms in 69% occurred within one year of residence in the Pescadores. The clinical course of scrub typhus and the serological response to infection were also studied. Eschar formation, fever, headache chills and lymph node enlargement were the predominant clinical manifestations noted. The indirect immunofluorescent antibody test (IFAT) demonstrated diagnostic (four-fold) rises in antibody titres to Rickettsia tsutsugamushi reference strains in 36 of 41 paired sera tested. 11 of 19 patients from whom only single sera were obtained had IFA titres presumptive of scrub typhus (greater than or equal to 1:160). Of 19 patients experiencing possible primary infections, 13 (68%) responded with antibodies directed against more than one reference strain of R. tsutsugamushi. These results suggest that several antigenically diverse strains of R. tsutsugamushi may be active in the Pescadores.

Diarrheal and respiratory disease aboard the hospital ship, USNS-Mercy T-AH 19, during Operation Desert Shield.

Diarrhea and respiratory disease were common problems among ground troops deployed to the Middle East during Operation Desert Shield. In order to determine the prevalence and impact of diarrheal and upper respiratory disease among shipboard personnel during this period, an epidemiologic survey was conducted on the hospital ship, USNS Mercy T-AH 19. An episode of acute diarrhea was reported by 46% of the surveyed population, and 79% reported upper respiratory symptoms. Six percent of personnel were temporarily unable to perform scheduled duties due to gastrointestinal symptoms and 7% due to respiratory symptoms. Officers were at increased risk of experiencing an episode of diarrhea, and female crew members more often reported respiratory complaints. Improved strategies to prevent diarrhea and respiratory disease among shipboard personnel are needed.

The Navy Forward Laboratory during Operations Desert Shield/Desert Storm.

The Navy Forward Laboratory (NFL) was an advanced infectious disease laboratory which provided a theater-wide reference diagnostic capability during Operations Desert Shield/Storm. During Operation Desert Shield, when massive numbers of troops were being deployed, the NFL primarily supported medical personnel in the diagnosis and treatment of infectious diseases. During the war, the laboratory provided rapid biologic warfare diagnostic support. The NFL demonstrated the benefits of a comprehensive, on-site diagnostic laboratory when large numbers of troops are deployed to high-risk areas and demonstrated the importance of military medical research laboratories for training of scientists and physicians, threat assessment, and product development.

Norfloxacin compared to trimethoprim/sulfamethoxazole for the treatment of travelers' diarrhea among U.S. military personnel deployed to South America and West Africa.

A randomized treatment trial of travelers' diarrhea was carried out among U.S. military personnel participating in routine exercises in several port cities in South America and West Africa. A 5-day, twice daily course of either norfloxacin (400 mg) or trimethoprim/sulfamethoxazole (TMP/SMX, 160/800 mg) was given to 142 volunteers. At the end of 5 days of treatment, diarrhea had resolved in 100% of 73 patients receiving norfloxacin and 97.1% (67/69) receiving TMP/SMX. A probable bacterial pathogen was determined in 44% of 142 subjects: 49% of the norfloxacin group and 39% of the TMP/SMX group. The most common pathogens detected were enterotoxigenic Escherichia coli in 20% of cases and rotavirus in 15%. Resistance to TMP/SMX was present in 20 (27%) bacterial isolates, while no resistance to norfloxacin was found. Eight of 10 patients in the TMP/SMX treatment group who had TMP/SMX-resistant bacterial enteropathogens improved clinically. Both norfloxacin and TMP/SMX were clinically effective in the treatment of travelers' diarrhea in this military population.

Campylobacter diarrhea in Alexandria, Egypt.

The role of Campylobacter as a cause of bacterial diarrhea in young children in Alexandria, Egypt was investigated. Stools or rectal swabs were collected from 880 children (mean age 9.8 months) presenting to a hospital with the primary complaint of diarrhea and from 1,079 well children (mean age 8.8 months) attending a vaccination clinic. Isolation of Campylobacter was significantly (p<0.0002) more frequent from cases (17.2%) than from controls (6.4%). Campylobacter was isolated from children presenting with diarrhea more frequently than Salmonella (3% isolation rate), Shigella (2% isolation rate), or other bacterial pathogens (1% isolatoin rate). Isolation of Campylobacter was significantly more frequent during the rainy season (p<0.0012). These results implicate Campylobacter as a major bacterial cause of diarrhea for which young children are brought for medical attention in Alexandria, Egypt.

Development and preclinical evaluation of a trivalent, formalin-inactivated Shigella whole-cell vaccine.

Studies were undertaken to manufacture a multivalent Shigella inactivated whole-cell vaccine that is safe, effective, and inexpensive. By using several formalin concentrations, temperatures, and incubation periods, an optimized set of inactivation conditions was established for Shigella flexneri 2a, S. sonnei, and S. flexneri 3a to produce inactivated whole cells expressing a full repertoire of Ipa proteins and lipopolysaccharide (LPS). The inactivation conditions selected were treatment with 0.2% formalin (S. flexneri 2a and 3a) or 0.6% formalin (S. sonnei) for 48 h at 25°C. Vaccine formulations prepared under different inactivation conditions, in different doses (10E5, 10E7, and 10E9 cells), and with or without the inclusion of double-mutant heat-labile toxin (dmLT) were evaluated in mice. Two intranasal immunizations with ≥10E7 inactivated whole cells resulted in high levels of anti-Invaplex and moderate levels of LPS-specific IgG and IgA in serum and in lung and intestinal wash samples. Addition of dmLT to the vaccine formulations did not significantly enhance humoral immunogenicity. Minimal humoral responses for IpaB, IpaC, or IpaD were detected after immunization with inactivated whole Shigella cells regardless of the vaccine inactivation conditions. In guinea pigs, monovalent formulations of S. flexneri 2a of 3a or S. sonnei consisting of 10E8, 10E9, or 10E10 cells were protective in a keratoconjunctivitis assay. A trivalent formulation provided protection against all three serotypes (S. flexneri 2a, P = 0.018; S. flexneri 3a, P = 0.04; S. sonnei, P < 0.0001). The inactivated Shigella whole-cell vaccine approach incorporates an uncomplicated manufacturing process that is compatible with multivalency and the future development of a broadly protective Shigella vaccine.