Management of travellers' diarrhoea

The most common health problem encountered in international travellers to topical and subtropical areas is diarrhoea. Even though it is not a life-threatening condition, it may influence deeply the quality of a vacation or the success of a business trip. The majority of cases of travellers' diarrhoea are due to bacterial pathogens, but viruses have also been implicated in a minority of patients. It is advocated that travellers with diarrhoea provide themselves with sources of salt (crackers or soup) and mineral water, to prevent and treat dehydration. Otherwise, treatment recommendations follow illness severity. For mild cases, symptomatic relief alone can be recommended. Loperamide is an effective agent improving diarrhoea and associated symptoms. For moderate diarrhoea (requiring a forced change in itinerary) combination therapy is advised using a fluoroquinolone together with loperamide. Severe diarrhoea [fever > 38 degrees C, dysentery (bloody stools) or incapacitating symptoms] should prompt the voyager to take an antibiotic alone for 3 to 5 days. Loperamide is relatively contraindicated in these cases. For the minority of patients receiving chemoprophylaxis to prevent travellers' diarrhoea, fluoroquinolones taken once a day while in the area at risk produce the highest protection rate (up to 95%). However, most authorities do not recommend routine prophylaxis for travellers.

Prophylactic effect of bovine anti-Cryptosporidium hyperimmune colostrum immunoglobulin in healthy volunteers challenged with Cryptosporidium parvum

Bovine hyperimmune anti-Cryptosporidium colostrum immunoglobulin (BACI) decreases the intensity of Cryptosporidium parvum infection in vitro. We investigated the prophylactic effect of BACI in healthy adults challenged with C. parvum. After we established an oocyst dose that resulted in 100% infection in four volunteers (baseline group), 16 volunteers were randomized to receive (1) BACI prior to C. parvum challenge (BACI group) and a nonfat milk placebo 30 minutes later, (2) BACI prior to and 30 minutes after challenge (reinforced BACI group), or (3) nonfat milk placebo prior to and 30 minutes after challenge. Subjects received BACI (10 g) or nonfat milk placebo three times a day for a total of 5 days and were followed for clinical symptoms and oocyst excretion for 30 days. A trend toward less diarrhea (P = .08) was observed for subjects receiving BACI in comparison with occurrences in placebo recipients. Subjects receiving BACI or nonfat milk placebo had a 100-fold reduction in oocyst excretion as compared with excretion in the baseline group.

Susceptibility and serologic response of healthy adults to reinfection with Cryptosporidium parvum

Healthy adults are susceptible to infection with small numbers of Cryptosporidium parvum oocysts, resulting in self-limited infection. We investigated if infection of humans with C. parvum is protective 1 year after primary exposure. At 1 year after a primary challenge with 30 to 10(6) oocysts, 19 healthy immunocompetent adults were rechallenged with 500 oocysts and monitored for the development of infection and/or illness. Oocyst excretion was quantitated by direct immunofluorescence with a C. parvum-specific monoclonal antibody, and anti-C. parvum antibodies in serum were detected by an enzyme-linked immunosorbent assay. Fewer subjects shed oocysts after the second exposure (3 of 19; 16%) than after the first exposure (12 of 19; 63%) (P < 0.005). Although the rates of diarrhea were comparable after each of the two exposures, the clinical severity as determined by the mean number of unformed stools passed was lower after reexposure (11.25 versus 8.62; P < 0.05). The number of anti-Cryptosporidium immunoglobulin G and A seroconversions increased after secondary exposure. However, the C. parvum serum antibody response did not correlate with the presence or absence of infection.

HEp-2 cell-adherent Escherichia coli and intestinal secretory immune response to human immunodeficiency virus (HIV) in outpatients with HIV-associated diarrhea

HEp-2 cell-adherent Escherichia coli and the human immunodeficiency virus (HIV) itself have recently been incriminated as causes of chronic HIV-associated diarrhea. This study sought to determine the prevalence of these two agents among HIV-infected patients with diarrhea in an outpatient setting in the United States and to compare their prevalence to that of other commonly recognized enteropathogens known to be present in this population. HEp-2 cell-adherent E. coli was found in 20 of 83 (24.1%) patients with diarrhea. A diffuse pattern of adherence was the most common, found in 14 of 20 (70%) patients, followed by a localized adherence pattern (6 of 20; 30%). An intestinal secretory immune response against the p24 antigen of HIV was found in 9 of 34 (27.5%) patients with HIV-associated diarrhea. The following pathogens or products were also detected in lower frequencies: Cryptosporidium spp. (10.8%), Clostridium difficile toxin (8.8%), microsporidia (6%), Isospora belli (3.6%), Blastocystis hominis (2.4%), Giardia spp. (1.2%), Salmonella spp. (1.2%), and Mycobacterium spp. (1.2%). The role of HEp-2 cell-adherent E. coli and HIV enteric infections in patients with HIV-associated diarrhea deserves further study.

Prognostic Factors Related to Recovery from Diarrhea among U.S. Students with Diarrhea in Mexico

Background: Medical charts of subjects treated with placebo from five double-blinded placebo-controlled clinical trials were reviewed to determine pre-enrollment prognostic factors related to later recovery from diarrhea. Method: Recovery or time from initiation of a placebo until passage of the last unformed stool after being declared well was calculated for each subject. Results: A longer duration of diarrhea was associated with presence of fever (rate ratio = 0.34; 95% CI = 0.2-0.9), presence of an invasive pathogen in the stool (rate ratio = 0.35; 95% CI = 0.2-0.7) or a noninvasive pathogen in stool (rate ratio = 0.7; 95% CI = 0.6-1.0), severe abdominal pain or cramps (rate ratio = 0.5; 95% CI = 0.3-0.9), passage of more than five watery stools per 24 hours (rate ratio = 0.58; 95% CI = 0.4-0.8). Severe vomiting predicted a shorter duration of post-enrollment diarrhea (rate ratio = 2.43; 95% CI = 1.1-5.6). Conclusion: A number of clinical and microbiologic factors found in travelers with diarrhea in the present study predicted duration of untreated diarrhea. The authors suggest the use of antimicrobial therapy in travelers with predictors of a long duration of diarrhea. Data developed in the present study may be used to create a historical control for clinical trials of antidiarrheal compounds using the same study criteria.

Guidelines on acute infectious diarrhea in adults. The Practice Parameters Committee of the American College of Gastroenterology

Guidelines for clinical practice are intended to suggest preferable approaches to particular medical problems as established by the interpretation and collation of scientifically valid research, derived from an extensive review of published literature. When data are not available that will withstand objective scrutiny, a recommendation may be made based on a consensus of experts. Guidelines are intended to apply to the clinical situation for all physicians without regard to specialty. Guidelines are intended to be flexible, not necessarily indicating the only acceptable approach, and should be distinguished from standards of care that are inflexible and rarely violated. Given the wide range of choices in any health care problem, the physician should select the course best suited to the individual patient and the clinical situation presented. These guidelines are developed under the auspices of the American College of Gastroenterology and its Practice Parameters Committee. These guidelines are also approved by the governing boards of the American Gastroenterology Association and the American Society of Gastrointestinal Endoscopy. Expert opinion is solicited from the outset for the document. Guidelines are reviewed in depth by the Committee, with participation from experienced clinicians and others in related fields. The final recommendations are based on the data available at the time of the production of the document and may be updated with pertinent scientific developments at a later time. The following guidelines are intended for adults and not for pediatric patients.

Single Dose Ofloxacin plus Loperamide Compared with Single Dose or Three Days of Ofloxacin in the Treatment of Traveler's Diarrhea

Background: Although the use of the antimicrobial, trimethoprim-sulfamethoxazole, in combination with the antisecretory and antimotility agent, loperamide, has been shown to be efficacious in the treatment of traveler's diarrhea, the use of fluoroquinolone antimicrobials in combination with loperamide has less support in the literature. The present study was designed to compare the efficacy of ofloxacin versus ofloxacin plus loperamide in the treatment of acute traveler's diarrhea. Method: This prospective, randomized, evaluator-blinded treatment trial was conducted in Guadalajara, Mexico, during the summers of 1992-1994. Adults newly arrived in Mexico from the United States who developed acute diarrhea of less than 2 weeks' duration were randomized to receive orally either: A) ofloxacin, 400 mg once; B) ofloxacin, 200 mg twice a day for six doses; or C) ofloxacin, 400 mg once, plus loperamide, 4 mg once followed by 2 mg after each loose stool, not to exceed 16 mg per day, for 3 days. The duration of illness was the number of hours elapsed from the beginning of therapy to the passage of the last unformed stool. Results: Ofloxacin and loperamide were well tolerated. Combination therapy with single dose ofloxacin plus loperamide was significantly more efficacious in reducing the duration of diarrhea than single dose ofloxacin or ofloxacin given for 3 days (p <.00001). Furthermore, combination therapy was more efficacious when enterotoxigenic Escherichia coli (ETEC) was the pathogen (p <.01) or when no pathogen was isolated (p <.001). Sixty-three percent of subjects passed no further unformed stools after the initial doses of combination therapy, and 91% were well by the end of the first 24 hours. Conclusions: The combined use of a single dose of ofloxacin with loperamide is safe and more efficacious in the treatment of traveler's diarrhea than use of ofloxacin alone.

Serum and Intestinal Antitoxin Antibody Responses after Immunization with the Whole-Cell/Recombinant B Subunit (WC/rBS) Oral Cholera Vaccine in North American and Mexican Volunteers

Background: Immune protection against cholera infection is probably mediated in part by locally produced, intestinal secretory IgA (sIgA) antibodies. We study the kinetics of intestinal (sIgA) and systemic (serum IgG) antitoxin antibody responses after immunization with whole-cell/recombinant B subunit oral cholera vaccine (WC/rBS) in U.S. travelers to Mexico and Mexican volunteers. Methods: Two doses of WC/rBS were administered 10 days apart to ten U.S. adults, newly arrived in Mexico, and 18 Mexican nationals. Serum IgG and intestinal secretory IgA (sIgA) antibodies to the B subunit of cholera toxin were measured from day 0 to day 21 by a direct enzyme-linked immunosorbent assay (ELISA). Results: Positive serum IgG responses to vaccination were detected in 80% of U.S. adults and in 59% of Mexican adults. All volunteers, regardless of nationality, developed a positive sIgA antibody response to WC/rBS. No differences were observed between U.S. and Mexican volunteers in the magnitude and kinetics of serum IgG responses. We recorded differences in the kinetics of sIgA antibody, with early and late peak sIgA antitoxin responses demonstrated in the Mexican and U.S. volunteer groups, respectively. Although the presence or absence of antitoxin sIgA antibodies prevaccination (sIgA titer > 1:4) did not interfere with the final postimmunization magnitude of the antibody responses (sIgA measurements days 14 and 21), the initial measurement curves showed differences (sIgA measurements days 0 and 3). Conclusions: The WC/rBS vaccine stimulated antitoxin antibody formation both in serum and locally in the intestine. The presence or absence of specific sIgA antibodies prevaccination did not seem to interfere with the magnitude of the antibody responses postvaccination (days 14, 21). The measurement of sIgA responses in fecal extracts appears to provide a simple and sensitive method to assess the intestinal immune response to orally administered vaccines.

Major differences in the spectrum of gastrointestinal infections associated with AIDS in India versus the west: an autopsy study

The spectrum of bowel infections in patients with AIDS in India is not well characterized. To examine this spectrum of infections, an autopsy study of 49 subjects was carried out. Multiple sections were obtained from the gastrointestinal tract. A pathogenic organism was detected in 25 (71%) of 35 patients with diarrhea vs. 4 (29%) of 14 patients without diarrhea (P < .01). The most frequent pathogen was cytomegalovirus (in 13; 27%), followed by parasites (9; 18%), fungi (8; 16%) and Mycobacterium tuberculosis (7; 14%). This is the first autopsy study of patients with AIDS in the Indian subcontinent and shows important differences in the profile of their opportunistic infections compared with those of such patients in the West. These findings will help define the optimal diagnostic and therapeutic approaches to patients with AIDS, which, in view of the considerable budgetary restrictions in developing countries, should be targeted toward the pathogens most frequently identified in such areas.

Practical guidelines for the treatment of cholera

Cholera is a dramatic clinical illness that requires rapid diagnosis and aggressive therapy. Clinical signs and symptoms of mild, moderate and severe dehydration must be determined, before beginning fluid therapy. Fluid therapy has 2 phases: rehydration (first 3 to 4 hours to correct deficits) and maintenance (to match continuing losses). The route and speed of fluid administration will depend on the degree of dehydration. Patients with severe dehydration should be treated intravenously, as should those patients who do not tolerate oral rehydration solution (ORS). Ringer's lactate is the preferred intravenous solution, although normal saline may be used along with ORS. For most patients with cholera, an ORS using one of the higher sodium-containing solutions and plain water optimally provide the fluid and salt needed. Close monitoring of intake, outputs and hydration status should be performed for all patients. Antimicrobial therapy should be given to moderately and severely ill patients in order to decrease the volume of fluids lost and to shorten the period of excretion of vibrios.

Cryptosporidium, isospora and strongyloides in AIDS

BACKGROUND

Diarrhoea is a common presentation in patients with AIDS. It occurs due to a number of parasites which are seldom seen in immunocompetent hosts.

METHODS

Between January 1993 and July 1994, faecal specimens from 77 patients with AIDS presenting with diarrhoea of more than a month's duration were examined by direct wet mount microscopy of saline and iodine preparations and by the modified Ziehl-Neelsen stain.

RESULTS

Cryptosporidium, Isospora and Strongyloides stercoralis alone or in combination were present in 29 of the 77 patients.

CONCLUSION

The presence of these parasites highlights their pathogenic potential for immunocompromised patients with AIDS. Diarrhoea due to Isosporais responsive to treatment, hence their identification has therapeutic implications as well.

Cryptosporidium parvum: intensity of infection and oocyst excretion patterns in healthy volunteers

Data about human Cryptosporidium parvum infection have originated from travelers, community and day care center outbreaks, and persons infected with the human immunodeficiency virus. In addition, experimental infection in 29 antibody-negative, healthy, adult volunteers generated information on the dose-infection response of C. parvum (Iowa strain). In that report, low inocula were sufficient to cause infection in 18 and illness in 7 persons. To further define the duration and intensity of infection in this population, oocyst shedding patterns were investigated in the 18 subjects infected with C. parvum. Oocyst quantitation revealed that volunteers with diarrheal illness (n = 7) excreted more oocysts over the course of the infection than did volunteers without diarrhea (n = 11; P < .05). Symptomatic subjects were more likely to shed oocysts on consecutive days. Further, a statistical nonsignificant inverse trend (r2 = .330, P = .136) was seen between challenge dose and total excreted oocysts. This paradox may relate to receptor saturation or a toxic effect on cells, parasites, or both afforded by a high inoculum.

Persistent diarrhea in travelers

Most patients with traveler's diarrhea can be efficiently treated with available pharmacological agents. A more difficult problem is the persistent diarrhea (lasting > or = 14 days) that occurs in approximately 3% of travelers who have acute diarrhea. In the initial evaluation of these patients, ideally three stool samples should be obtained for examination for pathogens. If an agent is not identified or the patient has not responded to specific therapy, he or she may be empirically treated with an antimicrobial drug directed toward common bacterial enteropathogens, if such treatment has not already been administered. For those patients whose conditions do not respond, antiprotozoal therapy may be employed empirically. If diarrhea continues, then an endoscopic evaluation is indicated, and specific treatment can be given if an agent or condition is identified. A proportion of patients will continue to have diarrhea following empirical therapy and a gastroenterologic workup. These individuals are best given symptomatic treatment and reassured that the prognosis is good.

Impact of the human immunodeficiency virus type-1 on common pediatric illnesses in Zambia

The seroprevalence of HIV-1 and in-patient mortality in children with common pediatric illnesses was studied. Between October 1990 and July 1991 at the Department of Paediatrics and Child Health, University Teaching Hospital (UTH), Lusaka, Zambia, mothers of all pediatric admissions were interviewed and counselled for enrollment of their children into the study. Of a total of 1323 children seen, 1266 children (600 female and 666 male) were enrolled into the study. Pneumonia (28 per cent), malaria (24 per cent), malnutrition (18 per cent), and diarrhoea (10 per cent) constituted over 80 per cent of the total admission diagnoses. Tuberculosis (5 per cent) was the fifth commonest cause of admission (61 out of 1266 children). A total of 354 out of the 1266 (28 per cent) children were found to be seropositive for HIV-1 compared to a seroprevalence rate of 9 per cent in children attending accident and emergency for traumatic injuries (P=0.001). High HIV-1 seroprevalence rates were found in children with tuberculosis (69 per cent), malnutrition (41 per cent), pneumonia (28 per cent). and diarrhoea (24 per cent). The overall mortality in hospital among HIV-seropositive children (19 per cent) was significantly higher than those who were HIV-seronegative (9 per cent) (P = < 0.0001).

The timing of breastfeeding initiation and its correlates in a cohort of rural Egyptian infants

Recent data on the patterns and correlates of the timing of breastfeeding initiation in newborns are scanty for many countries including Egypt. To obtain such data in four villages in rural Bilbeis, we recruited apparently healthy, single neonates and their apparently healthy mothers within 4 days of child birth, and followed them prospectively during 1987 through 1989. All 150 neonates included in the analyses were breastfed for some duration. At the time of the first breastfeed, 36, 37, and 27 per cent of the neonates were aged < 2, 2-5, and > or = 6 hours, respectively. All neonates had received the first breastfeed by age 72 hours. In a multivariate, polytomous logistic regression model, modern birth attendants and longer ( > 8 hours) duration of labour were significantly associated with deferment of breastfeeding initiation till the neonate was aged > or = 6 hours. Breastfeeding initiation appeared to be unduly delayed in our study mothers and infants given that they were apparently healthy during the early post-partum period. Later initiation of breastfeeding was associated with indiscriminate prelacteal feeding, earlier termination of breastfeeding, and unwelcome supplementation practices. Our findings emphasize the need to initiate and/or strengthen programmes to promote appropriate breastfeeding practices in Bilbeis and other comparable areas.

Zaldaride maleate (a new calmodulin antagonist) versus loperamide in the treatment of traveler's diarrhea: randomized, placebo-controlled trial

The present study was undertaken to compare the efficacy of a new calmodulin antagonist, zaldaride maleate, with that of placebo or loperamide in persons with traveler's diarrhea. One hundred seventy-nine patients were randomized to receive loperamide (4 mg followed by 2 mg after each unformed stool), zaldaride maleate (20 mg four times per day), or placebo. During the initial 48 hours of therapy, zaldaride maleate decreased the number of unformed stools by 30% and the duration of illness by 23% when compared with placebo. Loperamide was superior to both zaldaride maleate and placebo during the initial hours of treatment. However, after 48 hours of treatment, loperamide and zaldaride maleate were equally efficacious, decreasing by > 50% the number of unformed stools passed in a 24-hour interval (P, not significant), and were both superior when compared with placebo (P < .0001 and P = .0048, respectively). The apparent superiority of loperamide early in the course of therapy appeared to be related to a loading-dose effect and not to any differences in antidiarrheal properties.

Lack of correlation between diarrhea and weight loss in HIV-positive outpatients in Houston, Texas

To determine the prevalence of diarrhea and weight loss among human immunodeficiency virus (HIV)-positive patients, we reviewed the records of all patients attending the Harris County HIV Clinic during a 4-month time period. Diarrhea was considered persistent if it had been present for > 14 days or on two or more consecutive clinic visits. Weight loss was defined as moderate (5-10% reduction in weight) or severe (> 10% reduction) when the present weight was compared with the weight found at the initial clinic visit. Records were reviewed for 1,370 patients, of whom 12.2% complained of diarrhea (7.7% acute and 4.5% persistent). Diarrhea was more common among patients with a history of male-to-male sexual contact than in patients with other HIV risk factors (p < 0.003 for acute and p < 0.006 for persistent). The mean CD4 cell count was not significantly different in patients with or without persistent diarrhea (176 versus 212) or acute diarrhea (215 versus 212). Weight loss was reported in 25.2% of subjects (12.8% moderate and 12.4% severe). It did not correlate with CD4 count. Persistent diarrhea also was not associated with weight loss. Acute and persistent diarrhea were common among ambulatory HIV-positive patients, particularly in homosexual men. We did not identify a correlation among diarrhea, weight loss, and CD4 count. Thus, factors other than chronic diarrhea and immunosuppression appear to be responsible for weight loss in HIV-infected patients.