Phenotypic and genotypic analysis of enterotoxigenic Escherichia coli in samples obtained from Egyptian children presenting to referral hospitals.

Hospital surveillance was established in the Nile River Delta to increase the understanding of the epidemiology of diarrheal disease among Egyptian children. Between September 2000 and August 2003, samples obtained from children less than 5 years of age who had diarrhea and who were seeking hospital care were cultured for enteric bacteria. Colonies from each culture with a morphology typical of that of Escherichia coli were tested for the heat-labile (LT) and heat-stable (ST) toxins by a GM-1-specific enzyme-linked immunosorbent assay and colonization factor (CF) antigens by an immunodot blot assay. Enterotoxigenic E. coli (ETEC) isolates were recovered from 320/1,540 (20.7%) children, and ETEC isolates expressing a known CF were identified in 151/320 (47%) samples. ST CFA/I, ST CS6, ST CS14, and LT and ST CS5 plus CS6 represented 75% of the CFs expressed by ETEC isolates expressing a detectable CF. Year-to-year variability in the proportion of ETEC isolates that expressed a detectable CF was observed (e.g., the proportion that expressed CFA/I ranged from 10% in year 1 to 21% in year 3); however, the relative proportions of ETEC isolates expressing a CF were similar over the reporting period. The proportion of CF-positive ETEC isolates was higher among isolates that expressed ST. ETEC isolates expressing CS6 were isolated significantly less often (P < 0.001) than isolates expressing CFA/I in children less than 1 year of age. Macrorestriction profiling of CFA/I-expressing ETEC isolates by using the restriction enzyme XbaI and pulsed-field gel electrophoresis demonstrated a wide genetic diversity among the isolates that did not directly correlate with the virulence of the pathogen. The genome plasticity demonstrated in the ETEC isolates collected in this work suggests an additional challenge to the development of a globally effective vaccine for ETEC.

Malaria among United States troops in Somalia.

PURPOSE: United States military personnel deployed to Somalia were at risk for malaria, including chloroquine-resistant Plasmodium falciparum malaria. This report details laboratory, clinical, preventive, and therapeutic aspects of malaria in this cohort. PATIENTS AND METHODS: The study took place in US military field hospitals in Somalia, with US troops deployed to Somalia between December 1992 and May 1993. Centralized clinical care and country-wide disease surveillance facilitated standardized laboratory diagnosis, clinical records, epidemiologic studies, and assessment of chemoprophylactic efficacy. RESULTS: Forty-eight cases of malaria occurred among US troops while in Somalia; 41 of these cases were P falciparum. Risk factors associated with malaria included: noncompliance with recommended chemoprophylaxis (odds ratio [OR] 2.4); failure to use bed nets (OR 2.6); and failure to keep sleeves rolled down (OR 2.2). Some patients developed malaria in spite of mefloquine (n = 8) or doxycycline (n = 5) levels of compatible with chemoprophylactic compliance. Five mefloquine failures had both serum levels > or = 650 ng/mL and metabolite:mefloquine ratios over 2, indicating chemoprophylactic failure. All cases were successfully treated, including 1 patient who developed cerebral malaria. CONCLUSIONS: P falciparum malaria attack rates were substantial in the first several weeks of Operation Restore Hope. While most cases occurred because of noncompliance with personal protective measures or chemoprophylaxis, both mefloquine and doxycycline chemoprophylactic failures occurred. Military or civilian travelers to East Africa must be scrupulous in their attention to both chemoprophylaxis and personal protection measures.

Characterization of P-type ATPase 3 in Plasmodium falciparum.

We report the nucleotide sequence, derived amino acid sequence and expression profile of P-type ATPase 3 (PfATPase3) from Plasmodium falciparum. An open reading frame of 7362 nucleotides, interrupted by a single intron of 168 nt, encoded a protein product of 2394 amino acids with a predicted MW of 282791 Da. Hydropathy analysis of PfATPase3 revealed six amino-terminal and six carboxyl-terminal membrane spanning regions (M1-12) flanking a large hydrophilic domain with a smaller hydrophilic loop between M4 and M5. Based on a phylogenetic comparison of conserved domains present in P-type ATPases from other organisms, PfATPase3 resembled a Type-V ATPase for which the transport affinity is unknown. The PfATPase3 topology was interrupted by four regions, termed 'inserts', unique to malarial P-type ATPases, which were high in asparagine residues and charged amino acids (inserts I1-I4). Inserts I1 and I3 also contained repeated amino acid motifs. The number and composition of repeated amino acid motifs in insert I3 were variable in seven P. falciparum strains tested. PfATPase3 was 80.2% similar to the non-insert portions of P. yoelii ATPase3, although their inserts differed in length and composition. PfATPase3 mRNA was most abundant relative to beta-tubulin during the latter half of the erythrocytic cycle and was also present in gametocytes. Using affinity-purified antibody to a 14 amino acid PfATPase3 epitope, a 260 kDa protein was detected by Western analysis. Based on immunofluorescence, the PfATPase3 protein was located intracellularly in gametocytes and, to a lesser extent, in late erythrocytic stages.

Diarrheal disease among military personnel during Operation Restore Hope, Somalia, 1992-1993.

The potential for widespread diarrheal disease was regarded as a substantial threat to U.S. troops participating in the early phases of Operation Restore Hope in Somalia. Outpatient surveillance of 20,859 U.S. troops deployed during the first eight weeks, however, indicated that a mean of only 0.8% (range 0.5-1.2%) of personnel sought care for diarrhea each week, and in three epidemiologic surveys, < 3% of troops reported experiencing a diarrheal illness per week. Despite these low overall attack rates, diarrhea accounted for 16% of 381 hospital admissions and 20% of 245 patients admitted with a temperature > or = 38.5 degrees C. Sixty-one specimens were obtained from inpatients and 52 were obtained from outpatients. Shigella sp. were isolated from 33%, enterotoxigenic Escherichia coli from 16%, Giardia lamblia from 4%, and rotavirus from 1% of 113 stool samples obtained from inpatient (61) and outpatient (52) troops with diarrhea. Bacterial isolates obtained in Somalia were resistant to doxycycline (78%), ampicillin (54%), and sulfamethoxazole (49%), but uniformly sensitive to ciprofloxacin. With the exception of 10 Shigella sonnei isolates that were linked epidemiologically to one eating facility, bacterial pathogens occurred sporadically and demonstrated a wide variation of serotypes and antibiotic sensitivity patterns. Additionally, three of 11 paired sera collected from persons with nausea, vomiting, and watery diarrhea demonstrated a four-fold or greater increase in titer to Norwalk virus antibody. These data indicate that large outbreaks of diarrheal disease did not occur; however, highly drug-resistant enteric bacteria, and to a lesser extent viral and parasitic pathogens, were important causes of morbidity among U.S. troops in Somalia.

Dengue fever in U.S. troops during Operation Restore Hope, Somalia, 1992-1993.

Dengue fever (DF) was considered to be a potential cause of febrile illness in U.S. troops deployed to Somalia during Operation Restore Hope in 1992-1993. A prospective study of hospitalized troops with fever and a seroepidemiologic survey of 530 troops were conducted. Among 289 febrile troops hospitalized, 129 (45%) did not have an identified cause of their fever. Dengue (DEN) virus was recovered from 41 (43%) of 96 of these patients by inoculation of admission sera into C6/36 cell cultures. Thirty-nine (41%) of the isolates were identified as DEN-2 and two (2%) as DEN-3 by an indirect immunofluorescent antibody assay. An additional 18 (49%) of 37 culture-negative cases were shown by immunoglobulin M (IgM) antibody capture enzyme-linked immunosorbent assay to have anti-DEN virus antibody. All identified DF cases recovered within 1-2 weeks; no case of dengue hemorrhagic fever or shock syndrome was observed. A seroepidemiologic survey of a unit (n = 494) with 17 culture or serologically identified DF cases and a 13% attack rate of unidentified febrile illness revealed a 7.7% prevalence of anti-DEN virus IgM antibody. Failure to use bed nets was the only identified risk factor for DEN infection (adjusted odds ratio = 2.2, 95% confidence interval = 1.4-3.0). These data indicate that DF was an important cause of febrile illness among US troops in Somalia, and demonstrate the difficulties in preventing DEN infection in troops operating in field conditions.

Case series study of traveler's diarrhea in U.S. military personnel at Incirlik Air Base, Turkey.

Military personnel with traveler's diarrhea (n=202) while deployed to Incirlik Air Base, Turkey, from June to September 2002 were evaluated for pathogen-specific immune responses. Serologic and fecal immunoglobulin A (IgA) titers to enterotoxigenic Escherichia coli antigens (CS6, CS3, and LT) were quite low. In contrast, subjects with Campylobacter infections had high serologic and fecal IgA responses.

Detection of fecal and serum antibodies against enterotoxigenic Escherichia coli toxins and colonization factors in deployed U.S. military personnel during Operation Bright Star 2001--Egypt.

Infection caused by enterotoxigenic Escherichia coli (ETEC) poses a significant health problem in children and adults residing in endemic developing countries. Acute and convalescent paired stool and serum samples were obtained from 27 U.S. military personnel with ETEC-induced diarrhea during a military exercise in Egypt. In general, the concentration of total fecal and circulatory anti-LT IgA was significantly increased in convalescent specimens than in the paired acute ones in almost 65 % of the cases. The pattern of specific antibody responses in fecal and serum samples from cases with ETEC expressing the antigens coil surface 1 (CS1), CS2, CS3 and CS6 were, on the other hand, not conclusive due to the small numbers of the study cases. Further research is still required to understand the immunologic responses during the natural course of disease. The data obtained, nevertheless, may help current research efforts on the development of vaccines for humans against ETEC infection.

Respiratory disease among military personnel in Saudi Arabia during Operation Desert Shield.

OBJECTIVES: The purpose of this study was to determine whether respiratory disease due to crowded living conditions and high levels of suspended and blowing sand had a major adverse impact on US military personnel during Operation Desert Shield. METHODS: A questionnaire survey was administered to 2598 combat troops stationed in Northeast Saudi Arabia for a mean of 102 days. Samples of surface sand from seven different locations were analyzed by scanning electron microscopy and x-ray diffraction. RESULTS: Among surveyed troops, 34.4% reported a sore throat, 43.1% complained of a cough, 15.4% complained of chronic rhinorrhea, and 1.8% were unable to perform their routine duties because of upper respiratory symptoms. Evaluation of sleeping accommodations indicated that complaints of a sore throat and cough were most closely associated with sleeping in air-conditioned buildings; in contrast, complaints of rhinorrhea were associated with exposure to the outdoor environment while living in tents. Sand samples consisted mostly of quartz, with just 0.21% by weight of respirable size (< 10 microns in diameter). CONCLUSIONS: These findings indicate that upper respiratory complaints were frequent among Operation Desert Shield troops and were related both to the troops' housing and to their exposure to the outside environment.

Risk of viral hepatitis among military personnel assigned to US Navy ships.

A prevalence study of 2072 male US shipboard military personnel scheduled for deployment to South America/West Africa and the Mediterranean was conducted to determine whether serologic evidence of prior hepatitis A, B, or C infection is associated with exposure in foreign countries. There were 210 subjects (10.1%) who had antibodies to hepatitis A virus (anti-HAV), 76 (3.7%) to hepatitis B core antigen (anti-HBc), and 9 (0.4%) to hepatitis C virus (anti-HCV). By multivariate analysis, anti-HAV seropositivity was independently associated with age, non-white racial/ethnic groups, birth outside of the United States, and prior Caribbean deployment for less than 1 year. Anti-HBc seropositivity was independently associated with black and Filipino race/ethnicity, foreign birth, a history of a sexually transmitted disease, South Pacific/Indian Ocean deployment (less than 12 months), and South Pacific or Mediterranean duty for (greater than 1 year). No geographic risk factors were associated with anti-HCV positivity. These data indicate that military personnel deployed outside the United States are at increased risk of viral hepatitis infection and should be considered for vaccination.

Diarrheal disease during Operation Desert Shield.

BACKGROUND: Under combat conditions infectious disease can become a major threat to military forces. During Operation Desert Shield, there were numerous outbreaks of diarrhea among the U.S. forces. To evaluate the causes of and risk factors for diarrheal disease, we collected clinical and epidemiologic data from U.S. troops stationed in northeastern Saudi Arabia. METHODS: Between September and December 1990, stool cultures for enteric pathogens were obtained from 432 military personnel who presented with diarrhea, cramps, vomiting, or hematochezia. In addition, a questionnaire was administered to 2022 soldiers in U.S. military units located in various regions of Saudi Arabia. RESULTS: A bacterial enteric pathogen was identified in 49.5 percent of the troops with gastroenteritis. Enterotoxigenic Escherichia coli and Shigella sonnei were the most common bacterial pathogens. Of 125 E. coli infections, 39 percent were resistant to trimethoprim-sulfamethoxazole, 63 percent to tetracycline, and 48 percent to ampicillin. Of 113 shigella infections, 85 percent were resistant to trimethoprim-sulfamethoxazole, 68 percent to tetracycline, and 21 percent to ampicillin. All bacterial isolates were sensitive to norfloxacin and ciprofloxacin. After an average of two months in Saudi Arabia, 57 percent of the surveyed troops had at least one episode of diarrhea, and 20 percent reported that they were temporarily unable to carry out their duties because of diarrheal symptoms. Vomiting was infrequently reported as a primary symptom, but of 11 military personnel in whom vomiting was a major symptom, 9 (82 percent) had serologic evidence of infection with the Norwalk virus. CONCLUSIONS: Gastroenteritis caused by enterotoxigenic E. coli and shigella resistant to a number of drugs was a major problem that frequently interfered with the duties of U.S. troops during Operation Desert Shield.