Incubation periods of enteric illnesses in foodborne outbreaks, United States, 1998-2013.

Early in a foodborne disease outbreak investigation, illness incubation periods can help focus case interviews, case definitions, clinical and environmental evaluations and predict an aetiology. Data describing incubation periods are limited. We examined foodborne disease outbreaks from laboratory-confirmed, single aetiology, enteric bacterial and viral pathogens reported to United States foodborne disease outbreak surveillance from 1998-2013. We grouped pathogens by clinical presentation and analysed the reported median incubation period among all illnesses from the implicated pathogen for each outbreak as the outbreak incubation period. Outbreaks from preformed bacterial toxins (Staphylococcus aureus, Bacillus cereus and Clostridium perfringens) had the shortest outbreak incubation periods (4-10 h medians), distinct from that of Vibrio parahaemolyticus (17 h median). Norovirus, salmonella and shigella had longer but similar outbreak incubation periods (32-45 h medians); campylobacter and Shiga toxin-producing Escherichia coli had the longest among bacteria (62-87 h medians); hepatitis A had the longest overall (672 h median). Our results can help guide diagnostic and investigative strategies early in an outbreak investigation to suggest or rule out specific etiologies or, when the pathogen is known, the likely timeframe for exposure. They also point to possible differences in pathogenesis among pathogens causing broadly similar syndromes.

Produce-associated foodborne disease outbreaks, USA, 1998-2013.

The US Food Safety Modernization Act (FSMA) gives food safety regulators increased authority to require implementation of safety measures to reduce the contamination of produce. To evaluate the future impact of FSMA on food safety, a better understanding is needed regarding outbreaks attributed to the consumption of raw produce. Data reported to the US Centers for Disease Control and Prevention's Foodborne Disease Outbreak Surveillance System during 1998-2013 were analysed. During 1998-2013, there were 972 raw produce outbreaks reported resulting in 34 674 outbreak-associated illnesses, 2315 hospitalisations, and 72 deaths. Overall, the total number of foodborne outbreaks reported decreased by 38% during the study period and the number of raw produce outbreaks decreased 19% during the same period; however, the percentage of outbreaks attributed to raw produce among outbreaks with a food reported increased from 8% during 1998-2001 to 16% during 2010-2013. Raw produce outbreaks were most commonly attributed to vegetable row crops (38% of outbreaks), fruits (35%) and seeded vegetables (11%). The most common aetiologic agents identified were norovirus (54% of outbreaks), Salmonella enterica (21%) and Shiga toxin-producing Escherichia coli (10%). Food-handling errors were reported in 39% of outbreaks. The proportion of all foodborne outbreaks attributable to raw produce has been increasing. Evaluation of safety measures to address the contamination on farms, during processing and food preparation, should take into account the trends occurring before FSMA implementation.

Multistate outbreak of listeriosis caused by imported cheese and evidence of cross-contamination of other cheeses, USA, 2012.

Listeria monocytogenes is a foodborne pathogen that can cause bacteraemia, meningitis, and complications during pregnancy. In July 2012, molecular subtyping identified indistinguishable L. monocytogenes isolates from six patients and two samples of different cut and repackaged cheeses. A multistate outbreak investigation was initiated. Initial analyses identified an association between eating soft cheese and outbreak-related illness (odds ratio 17·3, 95% confidence interval 2·0-825·7) but no common brand. Cheese inventory data from locations where patients bought cheese and an additional location where repackaged cheese yielded the outbreak strain were compared to identify cheeses for microbiological sampling. Intact packages of imported ricotta salata yielded the outbreak strain. Fourteen jurisdictions reported 22 cases from March-October 2012, including four deaths and a fetal loss. Six patients ultimately reported eating ricotta salata; another reported eating cheese likely cut with equipment also used for contaminated ricotta salata, and nine more reported eating other cheeses that might also have been cross-contaminated. An FDA import alert and US and international recalls followed. Epidemiology-directed microbiological testing of suspect cheeses helped identify the outbreak source. Cross-contamination of cheese highlights the importance of using validated disinfectant protocols and routine cleaning and sanitizing after cutting each block or wheel.

2013 multistate outbreaks of Cyclospora cayetanensis infections associated with fresh produce: focus on the Texas investigations.

The 2013 multistate outbreaks contributed to the largest annual number of reported US cases of cyclosporiasis since 1997. In this paper we focus on investigations in Texas. We defined an outbreak-associated case as laboratory-confirmed cyclosporiasis in a person with illness onset between 1 June and 31 August 2013, with no history of international travel in the previous 14 days. Epidemiological, environmental, and traceback investigations were conducted. Of the 631 cases reported in the multistate outbreaks, Texas reported the greatest number of cases, 270 (43%). More than 70 clusters were identified in Texas, four of which were further investigated. One restaurant-associated cluster of 25 case-patients was selected for a case-control study. Consumption of cilantro was most strongly associated with illness on meal date-matched analysis (matched odds ratio 19·8, 95% confidence interval 4·0-∞). All case-patients in the other three clusters investigated also ate cilantro. Traceback investigations converged on three suppliers in Puebla, Mexico. Cilantro was the vehicle of infection in the four clusters investigated; the temporal association of these clusters with the large overall increase in cyclosporiasis cases in Texas suggests cilantro was the vehicle of infection for many other cases. However, the paucity of epidemiological and traceback information does not allow for a conclusive determination; moreover, molecular epidemiological tools for cyclosporiasis that could provide more definitive linkage between case clusters are needed.

Outbreak of Salmonella enterica serotype I 4,5,12:i:- infections: the challenges of hypothesis generation and microwave cooking.

We investigated an outbreak of 396 Salmonella enterica serotype I 4,5,12:i:- infections to determine the source. After 7 weeks of extensive hypothesis-generation interviews, no refined hypothesis was formed. Nevertheless, a case-control study was initiated. Subsequently, an iterative hypothesis-generation approach used by a single interviewing team identified brand A not-ready-to-eat frozen pot pies as a likely vehicle. The case-control study, modified to assess this new hypothesis, along with product testing indicated that the turkey variety of pot pies was responsible. Review of product labels identified inconsistent language regarding preparation, and the cooking instructions included undefined microwave wattage categories. Surveys found that most patients did not follow the product's cooking instructions and did not know their oven's wattage. The manufacturer voluntarily recalled pot pies and improved the product's cooking instructions. This investigation highlights the value of careful hypothesis-generation and the risks posed by frozen not-ready-to-eat microwavable foods.

Common source outbreaks of Campylobacter infection in the USA, 1997-2008.

Campylobacter is a common but decreasing cause of foodborne infections in the USA. Outbreaks are uncommon and have historically differed from sporadic cases in seasonality and contamination source. We reviewed reported outbreaks of campylobacteriosis. From 1997 to 2008, 262 outbreaks were reported, with 9135 illnesses, 159 hospitalizations, and three deaths. The annual mean was 16 outbreaks for 1997-2002, and 28 outbreaks for 2003-2008. Almost half occurred in warmer months. Foodborne transmission was reported in 225 (86%) outbreaks, water in 24 (9%), and animal contact in seven (3%). Dairy products were implicated in 65 (29%) foodborne outbreaks, poultry in 25 (11%), and produce in 12 (5%). Reported outbreaks increased during a period of declining overall incidence, and seasonality of outbreaks resembled that of sporadic infections. Unlike sporadic illnesses, which are primarily attributed to poultry, dairy products are the most common vehicle identified for outbreaks.

Real-time modelling used for outbreak management during a cholera epidemic, Haiti, 2010-2011.

The emergence of epidemic cholera in post-earthquake Haiti portended a public health disaster of uncertain magnitude. In order to coordinate relief efforts in an environment with limited healthcare infrastructure and stretched resources, timely and realistic projections of the extent of the cholera outbreak were crucial. Projections were shared with Government and partner organizations beginning 5 days after the first reported case and were updated using progressively more advanced methods as more surveillance data became available. The first projection estimated that 105 000 cholera cases would occur in the first year. Subsequent projections using different methods estimated up to 652 000 cases and 163 000-247 000 hospitalizations during the first year. Current surveillance data show these projections to have provided reasonable approximations of the observed epidemic. Providing the real-time projections allowed Haitian ministries and external aid organizations to better plan and implement response measures during the evolving epidemic.

Drug-resistant Salmonella in the United States: an epidemiologic perspective.

Salmonellosis poses a health problem of large proportions in the United States. Annually, it accounts for more than 40,000 reported cases, 500 deaths, and financial costs well in excess of $50 million. Antimicrobial resistance is increasing in Salmonella strains, a finding that has important public health implications. Although the chain of transmission of the bacteria is often complex, combined epidemiologic and laboratory studies with the use of new methods in molecular biology make it possible to trace antimicrobial-resistant salmonellae to their primary source--foods of animal origin. These studies suggest that the antimicrobial drugs to which food animals are exposed provide selective pressure that leads to the appearance and persistence of resistant strains.

Molecular phylogeny of the salmonellae: relationships among Salmonella species and subspecies determined from four housekeeping genes and evidence of lateral gene transfer events.

The salmonellae are a diverse group of bacteria within the family Enterobacteriaceae that includes two species, Salmonella enterica and Salmonella bongori. In order to characterize the phylogenetic relationships of the species and subspecies of Salmonella, we analyzed four housekeeping genes, gapA, phoP, mdh and recA, comprising 3,459 bp of nucleotide sequence data for each isolate sequenced. Sixty-one isolates representing the most common serotypes of the seven subspecies of Salmonella enterica and six isolates of Salmonella bongori were included in this study. We present a robust phylogeny of the Salmonella species and subspecies that clearly defines the lineages comprising diphasic and monophasic subspecies. Evidence of intersubspecies lateral gene transfer of the housekeeping gene recA, which has not previously been reported, was obtained.

Cholera: nice bacteria and bad viruses.

The genes coding for cholera toxin are borne on, and can be infectiously transmitted by, a filamentous bacteriophage, raising intriguing questions about the mechanisms and evolution of bacterial pathogenesis, and the taxonomy, epidemiology and control of cholera and other bacterial diseases.

Cholera in the United States, 1965-1991. Risks at home and abroad.

OBJECTIVE: To assess risks for cholera in the United States. DESIGN: Review of published reports of cholera outbreaks and sporadic cases and Centers for Disease Control and Prevention (CDC) memoranda and laboratory reports. PATIENTS: Persons with symptomatic laboratory-diagnosed cholera treated in the United States and territories. RESULTS: From 1965 through 1991, 136 cases of cholera were reported. Fifty-three percent of the patients were hospitalized and three persons died (case-fatality rate, 0.02). Ninety-three infections were acquired in the United States and 42 overseas; for one case the source was unknown. Domestically acquired cholera was largely related to the endemic Gulf Coast focus of Vibrio cholerae 01 (56 cases). The major domestic food vehicle was shellfish, particularly crabs harvested from the Gulf of Mexico or nearby estuaries. In 1991, 14 (54%) of 26 domestically acquired cases were caused by food from Ecuador (n = 11) and Thailand (n = 3). During 1991, the first cases of cholera in travelers returning from South America were reported. In 1991, the rate of cholera among air travelers returning from South America was estimated as 0.3 per 100,000; among air travelers returning from Ecuador, 2.6 per 100,000. CONCLUSIONS: Cholera remains a small but persistent risk in the United States and for travelers. An endemic focus on the Gulf Coast, the continuing global pandemic, and the epidemic in South America make this likely to continue for years to come. Physicians should know how to diagnose and treat cholera and should report all suspected cases to their state health departments.

Typhoid fever in the United States, 1985-1994: changing risks of international travel and increasing antimicrobial resistance.

BACKGROUND: Typhoid fever is a potentially fatal illness common in the less industrialized world. In the United States, the majority of cases occur in travelers to other countries. METHODS: We reviewed surveillance forms submitted to the Centers for Disease Control and Prevention, Atlanta, Ga, for patients with culture-confirmed typhoid fever between 1985 and 1994. RESULTS: The Centers for Disease Control and Prevention received report forms for 2445 cases of typhoid fever. Median age of patients was 24 years (range, 0-89 years). Ten (0.4%) died. Seventy-two percent reported international travel within the 30 days before onset of illness. Six countries accounted for 80% of cases: Mexico (28%), India (25%), the Philippines (10%), Pakistan (8%), El Salvador (5%), and Haiti (4%). The percentage of cases associated with visiting Mexico decreased from 46% in 1985 to 23% in 1994, while the percentage of cases associated with visiting the Indian subcontinent increased from 25% in 1985 to 37% in 1994. The incidence of typhoid fever in US citizens traveling to the Indian subcontinent was at least 18 times higher than for any other geographic region. Complete data on antimicrobial susceptibility to ampicillin, chloramphenicol, and trimethoprim-sulfamethoxazole were reported for 330 (13%) Salmonella Typhi isolates. Isolates from 1990 to 1994 were more likely than isolates from 1985 to 1989 to be resistant to any of these antimicrobial agents (30% vs 12%; P<.001) and to be resistant to all 3 agents (12% vs 0.6%; P<.001). CONCLUSIONS: American travelers to less industrialized countries, especially those traveling to the Indian subcontinent, continue to be at risk for typhoid fever. Antimicrobial resistance has increased, and a quinolone or third-generation cephalosporin may be the best choice for empirical treatment of typhoid fever.

Preventable disease in correctional facilities. Desmoteric foodborne outbreaks in the United States, 1974-1991.

BACKGROUND: Various disease outbreaks have been reported among prisoners. Recent foodborne outbreaks in correctional facilities in Georgia and Delaware prompted us to review the epidemiological characteristics of such outbreaks reported in the United States. METHODS: Foodborne outbreaks reported to the Centers for Disease Control and Prevention as part of routine surveillance from 1974 to 1991 were examined to identify outbreaks in jails, prisons, correctional facilities, and juvenile detention centers. Outbreak sizes, temporal trends, food vehicles, pathogens, and hygienic transgressions were analyzed. RESULTS: Eighty-eight desmoteric foodborne outbreaks involving 14307 cases of illness were reported from 31 states and territories. The mean outbreak size was 163 cases, compared with a mean of 31 cases for the 9107 reported outbreaks not involving prisoners. No fatalities among prisoners were reported. No pathogen was identified in 47 (53%) of the 88 outbreaks Salmonella species accounted for 15 (37%) of 41 outbreaks of known cause from 1974 to 1991, Clostridium perfringens for 14 (34%), and Staphylococcus aureus for 9 (22%). Fourteen of 15 Salmonella outbreaks occurred from 1984 to 1991. Food vehicles were reported for 63 (72%) of the outbreaks. Beef and poultry each were implicated in 9 (14%) of these, followed by fish or poultry salads and Mexican food, which accounted for 6 outbreaks (10%). Food-handling errors were reported for 69 (78%) of the 88 outbreaks. Improper food storage was reported in 62 (90%) of these. CONCLUSIONS: Foodborne outbreaks are reported regularly from correctional facilities in the United States. Outbreaks caused by Salmonella species, a special threat to prisoners with human immunodeficiency virus infection, seem to be increasing. Food production in correctional facilities should meet minimum safety standards, including sufficient refrigeration facilities, training of food handlers, and exemption of ill food handlers from work.

A multistate outbreak of Salmonella enterica Serotype Newport infection linked to mango consumption: impact of water-dip disinfestation technology.

Fresh produce increasingly is recognized as an important source of salmonellosis in the United States. In December 1999, the Centers for Disease Control and Prevention detected a nationwide increase in Salmonella serotype Newport (SN) infections that had occurred during the previous month. SN isolates recovered from patients in this cluster had indistinguishable pulsed-field gel electrophoresis (PFGE) patterns (which identified the outbreak strain), suggesting a common source. Seventy-eight patients from 13 states were infected with the outbreak strain. Fifteen patients were hospitalized; 2 died. Among 28 patients enrolled in the matched case-control study, 14 (50%) reported they ate mangoes in the 5 days before illness onset, compared with 4 (10%) of the control subjects during the same period (matched odds ratio, 21.6; 95% confidence interval, 3.53- infinity; P=.0001). Traceback of the implicated mangoes led to a single Brazilian farm, where we identified hot water treatment as a possible point of contamination; this is a relatively new process to prevent importation of an agricultural pest, the Mediterranean fruit fly. This is the first reported outbreak of salmonellosis implicating mangoes. PFGE was critical to the timely recognition of this nationwide outbreak. This outbreak highlights the potential global health impact of foodborne diseases and newly implemented food processes.

Diarrhea among African children born to human immunodeficiency virus 1-infected mothers: clinical, microbiologic and epidemiologic features.

Diarrhea and weight loss are common features of pediatric and adult human immunodeficiency type 1 (HIV-1) infection, particularly in developing countries. We studied prospectively episodes of diarrhea in 559 children, ages 10 to 15 months, participating in a longitudinal study of perinatal HIV-1 infection in Kinshasa, Zaire. Children with HIV-1 infection had more frequent episodes of diarrhea and were more likely to present with fever or moderate or severe dehydration and to have persistent or fatal diarrhea. Of 9 HIV-1-positive infants with diarrhea, 3 had enteroadherence factor-positive Escherichia coli, compared with 5 of 74 HIV-1-negative children with diarrhea (P = 0.04); no other pathogen was associated with HIV-1 infection. In a logistic regression model diarrhea was significantly associated with HIV-1 infection in the child, moderate or severe malnutrition and symptoms of acquired immunodeficiency syndrome in the mother. Diarrhea among children with perinatal HIV infection in Zaire is more severe than among uninfected children and is associated with malnutrition and advanced disease in the mother.

Chronic diarrhoeal illness in US Peace Corps volunteers.

Chronic diarrhoea of unknown aetiology is increasingly recognized as a problem in international travellers, and has been reported in US Peace Corps volunteers. In December 1987, we surveyed all Peace Corps medical officers to determine the magnitude of this problem and obtain preliminary data on potential risk factors. A rate of nine cases of chronic diarrhoea per 1000 volunteers per year was reported by medical officers representing 4607 volunteers in 43 countries. The highest rates were reported in Haiti, where one-third of the volunteers reportedly developed chronic diarrhoea during their two-year stay, as well as in Central and West Africa and Nepal. Volunteers were reported to drink unpasteurized milk routinely in eight (42%) of 19 countries with greater than or equal to one case of chronic diarrhoea during the previous two years, but in only two (11%) of 19 countries where none of the volunteers had chronic diarrhoea (odds ratio = 6.2, p = 0.06, Fisher exact test). Intensive prospective studies in areas of high incidence are needed to define this syndrome further.

Are there national risk factors for epidemic cholera? The correlation between socioeconomic and demographic indices and cholera incidence in Latin America.

BACKGROUND: From 1991 through 1995, all Latin American countries maintained cholera surveillance systems to track the epidemic that entered the region through Peru in January 1991. These data were used to assess correlations between socioeconomic and demographic indices that might serve as national risk predictors for epidemic cholera in Latin America. METHODS: Correlations between country-specific cumulative cholera incidence rates from 1991 through 1995 and infant mortality, the Human Development Index [HDI] a numerical value based on life expectancy, education, and income), gross national product (GNP) per capita, and female literacy were tested using the Pearson correlation coefficient. RESULTS: A total of 1,339,834 cholera cases with a cumulative incidence rate of 183 per 100,000 population were reported from affected Western Hemisphere countries from 1991 through 1995. Infant mortality rates were the most strongly correlated with cumulative cholera incidence based on the Pearson correlation coefficient. The HDI had a less strong negative correlation with cumulative cholera incidence. The GNP per capita and female literacy rates were weakly and negatively correlated with cholera cumulative incidence rates. CONCLUSIONS: Infant mortality and possibly the HDI may be useful indirect indices of the risk of sustained transmission of cholera within a Latin American country. Cumulative cholera incidence is decreased particularly in countries with infant mortality below 40 per 1000 live births. The lack of reported cholera cases in Uruguay and the Caribbean may reflect a low risk for ongoing transmission, consistent with socioeconomic and demographic indices. Cholera surveillance remains an important instrument for determining cholera trends within individual countries and regions.

PIP: To track a cholera epidemic that entered Latin America through Peru in January 1991, the region maintained cholera surveillance systems from 1991 through 1995. The present study used the surveillance data to identify socioeconomic and demographic indices that might serve as national risk predictors for epidemic cholera in Latin America. A total of 1,339,834 cholera cases, with a cumulative incidence rate of 183/100,000 population, were reported in 1991-95 from 22 countries in the region. Use of the Pearson correlation coefficient indicated that infant mortality rates were most strongly associated with cumulative cholera incidence. Cumulative cholera incidence was decreased in countries with an infant mortality below 40/1000 live births. The Human Development Index had a less strong negative correlation with cholera incidence, but values under 0.720 may provide an additional estimator of risk. The gross national product per capita (above US$2000) and female literacy rates above 90% were weakly and negatively correlated with cholera cumulative incidence rates. The continued lack of cholera cases in the Caribbean, where most countries have socioeconomic and demographic indices that resemble the Latin American countries with lowest risk for cholera, provides tentative support for this framework.

Using a knowledge, attitudes and practices survey to supplement findings of an outbreak investigation: cholera prevention measures during the 1991 epidemic in Peru.

BACKGROUND: To assess the effectiveness of the cholera prevention activities of the Peruvian Ministry of Health, we conducted a knowledge, attitudes, and practices (KAP) survey in urban and rural Amazon communities during the cholera epidemic in 1991. METHODS: We surveyed heads of 67 urban and 61 rural households to determine diarrhoea rates, sources of cholera prevention information, and knowledge, attitudes, and practices regarding ten cholera prevention measures. RESULTS: Twenty-five per cent of 482 urban and 11% of 454 rural household members had diarrhoea during the first 3-4 months of the epidemic. Exposure to mass media education was greater in urban areas, and education through interpersonal communication was more prevalent in rural villages. Ninety-three per cent of rural and 67% of urban respondents believed they could prevent cholera. The mean numbers of correct responses to ten knowledge questions were 7.8 for urban and 8.2 for rural respondents. Practices lagged behind knowledge and attitudes (mean correct response to ten possible: urban 4.9, rural 4.6). Seventy-five per cent of respondents drank untreated water and 91% ate unwashed produce, both of which were identified as cholera risk factors in a concurrently conducted case-control study. CONCLUSIONS: The cholera prevention campaign successfully educated respondents, but did not cause many to adopt preventive behaviours. Direct interpersonal education by community-based personnel may enhance the likelihood of translating education into changes in health behaviours. Knowledge, attitudes, and practices surveys conducted with case-control studies during an epidemic can be an effective method of refining education/control programmes.

PIP: The authors conducted a knowledge, attitudes, and practices (KAP) survey in urban and rural Amazon communities during the 1991 cholera epidemic to assess the effectiveness of the Peruvian Ministry of Health's cholera prevention activities. Diarrhea rates, sources of cholera prevention information, and knowledge, attitudes, and practices regarding 10 cholera prevention measures were determined by surveying the heads of 67 urban and 61 rural households. 25% of 482 urban and 11% of 454 rural household members had diarrhea during the first 3-4 months of the epidemic. Exposure to mass media education was greater in urban areas, while education through interpersonal communication prevailed in rural villages. 93% of rural and 67% of urban respondents believed they could prevent cholera. Rural respondents were slightly more knowledgeable than urban respondents about cholera. Overall, however, practices did not reflect their knowledge and attitudes; 75% of respondents drank untreated water and 91% ate unwashed produce.

Origins and consequences of antimicrobial-resistant nontyphoidal Salmonella: implications for the use of fluoroquinolones in food animals.

Human Salmonella infections are common; most infections are self-limiting, however severe disease may occur. Antimicrobial agents, while not essential for the treatment of Salmonella gastroenteritis, are essential for the treatment of thousands of patients each year with invasive infections. Fluoroquinolones and third-generation cephalosporins are the drugs-of-choice for invasive Salmonella infections in humans; alternative antimicrobial choices are limited by increasing antimicrobial resistance, limited efficacy, and less desirable pharmacodynamic properties. Antimicrobial-resistant Salmonella results from the use of antimicrobial agents in food animals, and these antimicrobial resistant Salmonella are subsequently transmitted to humans, usually through the food supply. The antimicrobial resistance patterns of isolates collected from persons with Salmonella infections show more resistance to antimicrobial agents used in agriculture than to antimicrobial agents used for the treatment of Salmonella infections in humans. Because of the adverse health consequences in humans and animals associated with the increasing prevalence of antimicrobial-resistant Salmonella, there is an urgent need to emphasize non-antimicrobial infection control strategies, such as improved sanitation and hygiene, to develop guidelines for the prudent usage of antimicrobial agents, and establishment of adequate public health safeguards to minimize the development and dissemination of antimicrobial resistance and dissemination of Salmonella resistant to these agents.

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.