Clinical features of ciguatera fish poisoning: a study of the disease in the US Virgin Islands.

Clinical data were obtained on 33 patients involved in 27 episodes of ciguatera fish poisoning occurring during a 14-week period on St Thomas in the US Virgin Islands. All patients had gastrointestinal tract symptoms, with 30 patients (91%) complaining of diarrhea and 23 patients (70%) complaining of vomiting; these symptoms occurred early in the disease and were of short duration. Twenty-three patients (70%) complained of malaise, and 19 patients (58%) had pain and weakness in the lower extremities. Dysesthesias were noted by 19 patients (58%); the median duration of dysesthesias was two weeks or more, with symptoms present is some cases for more than two months. Cardiovascular signs and symptoms, including both hypotension and bradycardia were noted in some acute cases. Therapy included antidiarrheal and antiemetic agents, intravenous fluids, atropine, and pralidoxime chloride. Efficacy of pralidoxime therapy could not be established on the basis of our data.

Equine antitoxin use and other factors that predict outcome in type A foodborne botulism.

The use of trivalent equine antitoxin in treating foodborne botulism has not been adequately assessed. One hundred thirty-two cases of type A foodborne botulism reported to the Centers for Disease Control in the period from 1973 to 1980 are reviewed to evaluate the effect of antitoxin therapy and other factors on the outcomes of patients with botulism. The fatality rates were higher in patients over 60 years old and in those who were index patients (the first or only patient in an outbreak). The clinical course was longer in patients over 60 years old, patients whose incubation period was less than 36 hours, and index patients. Patients who had received trivalent equine antitoxin had a lower fatality rate and a shorter course than those who did not receive antitoxin, even after controlling for age and incubation period. Patients who received antitoxin in the first 24 hours after onset had a shorter course but about the same fatality rate as those who received antitoxin later. These results suggest that trivalent antitoxin has a beneficial effect on survival and shortens the course of patients with type A botulism.

Fatal heat-related illness in naval cadets in Ecuador.

On 13 April 1982, after a 6 to 7 km training run on an extremely hot and humid day, 20 of 216 cadets at the Ecuadorian Naval Academy in Guayaquil became ill with symptoms of heat-related illness. Four of them suffered heat stroke, and three died. Illness was most highly associated with the amount of exercise performed that day but was significantly more common in first-year cadets than in older cadets. There were no differences in the anthropometric measurements of ill and well subjects. We conclude that heat-related illness can affect conditioned military personnel during routine training in severe weather and make recommendations for prevention.

Ciguatera fish poisoning epidemiology of the disease on St. Thomas, U.S. Virgin Islands.

In a random household survey conducted on St. Thomas, U.S. Virgin Islands, the incidence of ciguatera fish poisoning was found to be 36.5 cases per 1,000 population per 5 years (95% confidence limits +/- 16.9 cases per 1,000 population per 5 years). An average of 3.6 cases per 1,000 population per year were diagnosed in the hospital emergency room on St. Thomas. Cases seen in the emergency room occurred most frequently among persons aged 30-39 years. No clear seasonality for cases could be demonstrated. In an investigation of cases occurring between 1 January and 10 April 1980, illness was caused by a variety of different fish, with carrang (Caranx ruber) the species most commonly implicated. Patients and age-matched controls ate fish with equal frequency; patients were significantly more likely to have had previous episodes of ciguatera fish poisoning than were controls.

Outbreak of invasive Escherichia coli gastroenteritis on a cruise ship.

An invasive strain of Escherichia coli (ONT:NM) was isolated from stool specimens from 7 of 10 ill passengers who developed diarrhea during a 5-day ocean cruise. The ill passengers had shared no common exposures off the ship before or during the cruise. Three of the persons whose stools were cultured were part of a tour group of 219 persons, and a food consumption and health history questionnaire was completed by 190 members (87%) of this tour group. Forty-seven (25%) had had diarrhea during the cruise; other symptoms among those with diarrhea included nausea (72%), abdominal cramps (68%), headache (68%), chills (60%), dizziness (53%), myalgias (43%), subjective fever (36%), and vomiting (26%). The median duration of symptoms was 3 days. Eating at cold buffets on ship and eating potato salad, a buffet food item, were significantly associated with illness. No evidence of secondary spread of illness in household contacts of the ill person was found.

Non-01 Vibrio cholerae infections in Cancun, Mexico.

To determine the role of Vibrio cholerae as a cause of diarrheal illness in Cancun, Mexico, an investigation was conducted in July and August 1983. Although toxigenic V. cholerae 01 were not found, non-01 V. cholerae were isolated from 22 (16%) of 134 stools from persons with diarrheal illness and none of 22 stools from well persons; 58 (92%) of 63 sewage samples; 12 (86%) of 14 untreated well water samples; a home storage tank for treated water; and 5 (21%) of 24 samples of raw seafood. None of the V. cholerae isolates from patients were toxigenic. The illness occurred mainly in small children, and were characterized principally by diarrhea and abdominal pain. No patient was seriously ill, and all recovered without sequelae. Seven different serotypes of non-01 V. cholerae were isolated from the stool specimens, and Smith serotype 12 accounted for 10 (46%) of the 22 isolates. A matched-pair case-control study found that cases were more likely than controls to have eaten home prepared gelatin (P = 0.03, OR = 5/0) and seafood (P = 0.06, OR = 4/0).

Lethal paralytic shellfish poisoning in Guatemala.

An outbreak of paralytic shellfish poisoning occurred in Champerico, on the Pacific coast of Guatemala, July-August 1987. Of 187 people affected with characteristic neurologic symptoms, 26 died. A case study implicated a species of clam, Amphichaena kindermani, harvested from local beaches as the vehicle of the neurotoxins (saxitoxins). Children less than 6 years old had a higher fatality rate (50%) than people greater than 18 years of age (7%). The minimum lethal dose for 1 child was estimated to have been 140 mouse units of toxin/kg body weight; thus children may be more sensitive to the saxitoxins than are adults. This is the first large outbreak of paralytic shellfish poisoning recognized in Guatemala.

Epidemic cholera in Trujillo, Peru 1992: utility of a clinical case definition and shift in Vibrio cholerae O1 serotype.

Epidemic cholera continues in Peru. Since 1991, cholera surveillance in Peru has been based mainly on clinical recognition. To determine the proportion of reported cholera patients who actually have cholera and to evaluate the clinical case definition used in surveillance, we cultured rectal swabs from patients presenting with acute diarrhea in March 1992 in Trujillo, Peru. Of 197 patients meeting the clinical case definition, 174 (88%) had confirmed Vibrio cholerae O1 infection. In this epidemic setting, watery diarrhea of sudden onset in a person of any age presenting for treatment is highly predictive of cholera. Of note, 90% of the current V. cholerae O1 El Tor isolates were of serotype Ogawa, while a year earlier, all were of serotype Inaba.

Persistence of cholera in the United States.

In 1973, 1978, and 1981, cases of cholera were acquired along the Gulf Coast of the United States. The isolates from all of the cases were toxigenic Vibrio cholerae O-group 1, biotype El Tor, serotype Inaba, hemolytic, and of the same phage sensitivity pattern, and all had the same restriction endonuclease pattern by molecular genetic analysis. The strain from one of the two 1981 cases differed from the others in having a small plasmid and a negative Voges-Proskauer reaction. Multiple importations, chronic carriers, and continuous occurrence of undetected cases are unlikely explanations for these findings, which suggest that toxigenic V. cholerae 01 can multiply and persist for years in some environments, making eradication of cholera a formidable task.

The use of plasmid profiles and nucleic acid probes in epidemiologic investigations of foodborne, diarrheal diseases.

The application of nucleic acid analyses to investigations of infectious disease outbreaks has resulted in useful molecular strain markers that distinguish the epidemic clone of a particular pathogen and help identify specific vehicles of infection. We have successfully used plasmid profile analysis, restriction endonuclease digestion of plasmid and whole-cell DNAs, and nucleic acid hybridization to investigate recent outbreaks of foodborne diarrheal illness. Plasmid analysis has been important in identifying epidemic strains of Salmonella enteritidis and Escherichia coli O157:H7. In a culture survey of S. enteritidis isolates from humans and a variety of animals, including chickens and chicken eggs, we identified 16 distinct plasmid profiles and used these to differentiate strains, especially within commonly occurring phage types (Colindale 8 and 13a). HindIII digests of plasmid DNA were useful in distinguishing plasmids of similar mass but dissimilar enzyme target sequences; they clearly distinguished S. enteritidis strains causing systemic infections in children in parts of Africa from U.S. isolates. Investigations of outbreaks of hemorrhagic colitis have also been assisted by plasmid analysis. Restriction endonuclease digests of whole-cell DNA and Southern blot analysis, hybridizing with E. coli 16S and 23S rRNA (ribotyping), have been effective subtyping techniques, especially for plasmidless isolates of Campylobacter jejuni. In five outbreaks of C. jejuni infections, ribotyping of PvuII and ClaI digests distinguished individual epidemic strains within one commonly occurring C. jejuni serotype (Penner 2, Lior 4). Preliminary data show that ribotyping of NcoI digests can also distinguish individual epidemic strains of E. coli O157:H7 and may provide a more stable marker than plasmid profiles. Specific DNA probes derived from cloned virulence genes of E. coli have been invaluable in epidemic investigations and surveys. Using colony hybridization, we found in one survey of stool specimens from 174 dairy cattle that 11% of animals were asymptomatically carrying Shiga-like toxigenic E. coli other than O157:H7. We also found that newly synthesized oligonucleotide probes for the Shiga-like toxins I and II agreed 100% with cloned gene probes in a study of 613 E. coli strains. Future studies of these organisms will include the use of additional synthetic oligonucleotides as primers to amplify the toxin genes directly in patient and animal specimens by the polymerase chain reaction. There is a continuing and expanding role for molecular approaches in epidemiological investigations. The DNA methods described above are not based on the often complex expression of phenotypic characteristics, and, unlike sensitive and specific techniques such as phage typing, a single method can be used to study a variety of Gram-positive and negative bacterial pathogens.

Use of plasmid profiles to differentiate strains within specific serotypes of classical enteropathogenic Escherichia coli.

1. The usefulness of plasmid profile analysis to differentiate strains of enteropathogenic Escherichia coli (EPEC) was evaluated by studying 123 strains of the most prevalent serotypes causing infant diarrhea in the city of São Paulo, Brazil, i.e., O111ab:H-, O111ab:H2 and O119:H6. 2. No common profiles were found among strains of distinct serotypes. However, within each serotype, most of the strains were grouped within a few major profiles. More than 68% of the strains of serotypes O111ab:H- and O111ab:H2 were included in 6 and 9 major profiles, respectively. In serotype O119:H6, about 48% of the strains were included in 3 major profiles. 3. This analysis suggests that only a few EPEC clones are causing infant diarrhea in São Paulo and revealed that the distribution of serotypes O111ab:H- and O111ab:H2 during the one-year study was at least partly determined by small outbreaks of the most common profiles. 4. We conclude that plasmid profile analysis is very useful to differentiate strains within specific EPEC serotypes.

Epidemiology of cholera in the Americas.

A persisting reservoir of the Gulf Coast strain of toxigenic V. cholerae O1 in Louisiana and Texas marshes and the shipment of seafood from these areas throughout the United States means that sporadic cases and outbreaks of cholera may occur anywhere in the country for the foreseeable future. Such cases are most likely to occur during warm months, especially between July and October. Physicians should think of cholera when consulted for severe watery diarrhea, even when the patient has no history of travel, and alert the laboratory. Experience has shown that US food and water sanitation is good enough to make either secondary transmission or large outbreaks unlikely; however, as long as we have foodborne and waterborne outbreaks of bacterial enteric diseases, the Gulf Coast strain may appear in a situation in which it can multiply and be ingested in large numbers by many people. The Latin American cholera epidemic has caused more cases of cholera in the United States in 2 years than the total of Gulf Coast strain cases identified during the past 20 years. The epidemic's future is uncertain. Despite knowing a great deal about cholera epidemiology, we cannot fully explain the ebb and flow of cholera epidemics. We do not know why cholera was apparently eliminated from the Western Hemisphere by 1900, nor can we predict which areas will be affected next or whether cholera will remain in a given area transiently or become endemic. The fact that cholera disappeared from the Western Hemisphere in the last century does not necessarily mean that it will disappear again. The situation is different now in several ways. The current pandemic is caused by the El Tor biotype, which persists better in the environment than does the classical biotype. Travel is now more frequent and more rapid. Finally, the population of the Western Hemisphere is about 14 times larger now than it was in 1850 and produces about 80,000 metric tons of human feces each day, of which only a fraction is treated. Thus, cholera will probably become endemic in Latin America and persist indefinitely.

Vibrios on the half shell: what the walrus and the carpenter didn't know.

At least nine Vibrio species have been associated with disease in the United States. Vibrio fluvialis, V. hollisae, V. mimicus, and V. parahaemolyticus cause diarrheal diseases, but may also be encountered in extraintestinal infections such as wound and ear infections, septicemia, and cholecystitis. Vibrio alginolyticus, V. damsela, V. metschnikovii, and V. vulnificus primarily cause extraintestinal disease. Toxigenic V. cholerae O1 is the cause of epidemic cholera, whereas nontoxigenic V. cholerae O1 and non-O1 V. cholerae have been associated with both diarrheal and extraintestinal diseases. Most reports of vibrio infections have come from states along the Atlantic Ocean and Gulf of Mexico and from Hawaii, and most of the infections have occurred during summer and fall. Wound and ear infections have occurred after exposure to salty or brackish water or to drippings from raw seafoods. Foodborne vibrio infections are almost all caused by seafoods, especially oysters eaten raw. Thorough cooking and careful handling will render seafoods safe for consumption.

Foodborne outbreaks of campylobacteriosis: the United States experience, 1980-1982.

During 1980-1982, 23 foodborne outbreaks of diseases caused by Campylobacter were reported to the Centers for Diseases Control through the National Foodborne Surveillance Program, which collects reports from state and territorial epidemiologists throughout the United States. These outbreaks involved 748 ill persons, of whom 4% were hospitalized. For outbreaks with six or more ill persons, the median attack rate was 41%, the mean or median incubation periods ranged from 66 to 120 hours, and the mean duration of symptoms ranged from three to seven days. Raw milk was implicated or suspected in 14 outbreaks. In four of the other outbreaks, food handling errors were identified, and in five outbreaks, poultry, eggs, or beef were implicated or suspected. In three of four outbreaks in which Campylobacter was recovered from cows at the implicated dairies, some isolates from cows were serotypically identical to isolates from ill persons. In one egg-associated outbreak, one of the isolates of Campylobacter recovered from hens at the implicated egg farm was serotypically identical to an isolate recovered from an ill person. These findings underscore the hazard of eating undercooked or raw foods of animal origin such as raw milk. Raw milk contaminated by infected cows is a major cause of foodborne campylobacteriosis in the United States.

Is cholera a problem for US travelers?

Only ten cases of cholera in US travelers have been reported since the current cholera pandemic began in 1961. No important risk factors were apparent from assessing the age, place of acquisition, duration of mode of travel before infection, or history of cholera vaccination of the travelers who acquired cholera. All of the patients received medical treatment and all recovered; there were no secondary cases. Nine of the ten were infected by Vibrio cholerae 01 El Tor, the strain responsible for the current pandemic. Using the number of US citizens returning to the United States by commercial air carrier from Asia, Africa, and Oceania to estimate the population at risk, we found that the chance of acquiring a reported case of cholera is less than one case per 500,000 returning travelers.

Epidemiological usefulness of changes in hemolytic activity of Vibrio cholerae biotype El Tor during the seventh pandemic.

Hemolytic Vibrio cholerae biotype El Tor strains were isolated in the United States in 1973 and 1978 after they had supposedly disappeared worldwide during the 1960s and 1970s. We decided to examine the change in prevalence of hemolytic El Tor strains since the beginning of the seventh pandemic and evaluate the usefulness of hemolytic activity as an epidemiological marker. A total of 48 isolates of V. cholerae biotype El Tor isolated in the Eastern Hemisphere between 1960 and 1979, along with 1 Texas (1973) and 38 Louisiana (1978) isolates, were tested for hemolytic activity by each of four methods. One method (utilizing heart infusion broth with 1% glycerol) was slightly superior for detecting hemolytic activity. Titers obtained with this method ranged from less than 2 to 1,024. Of 13 (76.9%) strains from the earliest part of the current pandemic, 10 were hemolytic, compared with 1 of 26 (3.8%) strains isolated in the period from 1966 to 1979 in the Eastern Hemisphere, indicating that nonhemolytic El Tor strains have replaced the hemolytic variety there. In contrast, all 38 Louisiana isolates and the Texas isolate were strongly hemolytic. Hemolytic activity was concluded to be a useful epidemiological marker.

Staphylococcal food poisoning in the United States. New facts and old misconceptions.

To determine the current epidemiologic characteristics of staphylococcal food-borne disease (SFD), we reviewed 131 outbreaks reported to the Centers for Disease Control, Atlanta, from 1977 through 1981. Staphylococcal food-borne disease was the second most common cause of reported food-borne illness, affecting more than 7,000 persons during the five-year period; 10% of these patients visited or were admitted to hospitals for their illnesses. The proportion of outbreaks attributable to Staphylococcus aureus enterotoxins A through E has changed, with enterotoxin A being the only toxin incriminated during the last three years of this review. Milk--the most common source of enterotoxin C- and D-producing strains--and commercially packed foods are less common causes of SFD outbreaks now than they were before 1960. However, previously cooked, proteinaceous foods remain preeminent in causing SFD. The presence or absence of fever in infected persons, skin lesions in food handlers, or large numbers of staphylococci in food were unreliable as diagnostic criteria. Thorough epidemiologic investigation remains crucial to identifying SFD and its sources.