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An interstate common-source outbreak of salmonellosis was first detected in the United States in September and October, 1975, when a tenfold increase in Salmonella newport isolates was noted through routine salmonella surveillance by the Colorado Department of Health. Eighteen primary cases with a distinctive antibiotic resistance pattern (tetracycline, streptomycin, and sulfonamides) were evaluated in a case-control study, and illness was found to be associated with eating raw hamburger (p less than .001) from any store of one grocery chain (p less than .001). A Dallas, Texas, processing plant that supplied the Colorado markets also supplied other states, and these other states were alerted. Maryland discovered nine S. newport isolates with the same antibiogram and, as in the Colorado outbreak, illness was associated with eating raw or very rare ground beef from the same grocery chain (p less than .03). A third outbreak of S. newport with the same antibiogram occurred on a Florida military base. S. newport with the same antibiogram and a phage lysis pattern identical to those of the human epidemic isolates was cultured from frozen hamburger recovered in Colorado and Florida. The associated hamburger originated at the same Dallas, Texas, processing plant. A source of the epidemic strain was not identified, but the organism probably originated before delivery to the plant.

Isolates of Salmonella typhi from 3661 persons in the United States were reported to the Center for Disease Control from 1967 to 1972. Available case reports and carrier lists for the patients from whom the isolates were recovered were reviewed. During this period the yearly number of travel-associated cases rose 270% and, in contrast to indigenous cases, the number of travel-associated ones increased each year. This increase was largely due to cases associated in some way with Mexico. Furthermore, residents of the United States with Hispanic surnames were at higher risk of contracting typhoid in this country than was the rest of the population. Most indigenous cases were in children or young adults and were not linked to recognized outbreaks. Most known typhoid carriers in the United States are elderly women.

Between January 1 and March 15, 1974, approximately 1200 cases of acute gastrointestinal illness occurred in Richmond Heights, Florida, a residential community of 6500 in south Dade County. Over one-third of all families in the area had at least one member affected. The findings of 10 culture-proven cases of shigellosis among those who became ill and clinical signs and symptoms in the others suggest that most of the other cases that were not cultured may have been shigellosis also. Epidemiologic investigation showed that consumption of tap water was associated with illness in the initial cases of affected families. Evaluation of the Richmond Heights public water supply disclosed numerous inadequacies in both design and operation. One of the wells providing water to the community was continuously contaminated with excessive levels of fecal coliforms from a nearby septic tank, and a breakdown in chlorination on January 14-15 caused approximately 1 million gallons of inadequately chlorinated water from the contaminated well to be distributed to the community 48 hours before the epidemic began. Correction of deficiencies in the water plant was undertaken by the utility company; the residents of Richmond Heights were instructed to boil their drinking water or to use commercially bottled water pending completion of corrective measures. A FUll scale study is planned for all similar public water supplies in Dade County.

The first naturally acquired case of cholera reported in the United States since 1911 occurred in a 51-year-old resident of Port Lavaca, Texas. Extensive epidemiologic investigation of the patient's contacts and environment did not identify a cholera carrier of elucidate a pathway of transmission, but several avenues of investigation suggested possible means by which the patient may have acquired his infection. No secondary spread resulted from this case, and its occurrence did not endanger the community at large.

In this study we utilized the salt-tolerant characteristics of vibrios to develop a more selective medium by addition of NaCl to thiosulfate citrate bile salts sucrose (TCBS) agar. The effect of adding salt to TCBS agar varied greatly among brands of TCBS agar and between lots of the same brand. The addition of salt at concentrations as high as 1.5% (2.5% total NaCl) caused the inhibition of growth of three species of commonly encountered normal bowel flora and one strain of classical Vibrio cholerae but did not compromise the use of TCBS agar for isolation of V. cholerae biotype El Tor.

To evaluate the usefulness of the indirect hemagglutination (IHA) test in the epidemiological investigation of shigellosis, single serum specimens were tested from 50 patients with Shigella dysenteriae 1 (Shiga bacillus) infections, 103 asymptomatic contacts of these cases, 267 adult and 100 student control, and serum specimens collected during two outbreaks caused by S. sonnei and one outbreak due to S. flexneri 6. In patients with S. dysenteriae 1, 74% demonstrated titers of greater than or equal to 1:40, with 50% showing titers of greater than or equal to 1:160, whereas in the controls 10.4% had titers of greater than or equal to 1:40 and only 0.3% had titers of greater than or equal to 1:160. IHA titers in serum specimens collected from patients with S. sonnei and S. flexneri 6 were too low to be considered diagnostic for individual patients, but were useful in analysis of group results. Groups of ill individuals yielded titers significantly higher than non-ill groups; however, titers from ill groups were usually less than 1:40. The IHA test for S. dysenteriae 1 antibodies serves as a valuable adjunct to the diagnosis of Shiga bacillus dysentery. In our laboratory, an IHA titer of 1:40 or 1:80 is a "borderline positive." Shiga bacillus dysentery is strongly indicated when IHA titers are greater than or equal to 1:60.

In April-November 1974, Portugal had a cholera epidemic caused by Vibrio cholerae El Tor Inaba with 2467 bacteriologically confirmed hospitalized cases and 48 deaths. Most of the country was affected, with 17 of the 18 districts reporting cases. V. cholerae was isolated from 42 per cent of shellfish tested during the epidemic, and an epidemiologic study found that a history of consumption of raw or poorly cooked cockles was significantly more common among cholera patients than among paired controls. Water from a spring and a brand of commercially bottled water were also found to be vehicles of transmission of cholera. Although night soil was sometimes used on gardens, consumption of raw fruits and vegetables was not associated with illness.

During a cholera epidemic, Vibrio cholerae was isolated from two springs which supplied mineral water to a spa and to a commercial water bottling plant. Epidemiologic investigation found that cholera attack rates were 10-fold greater among visitors to the spa than among non-visitors. A subsequent matched-pair case-control study which excluded persons who had visted the spa showed that a history of consumption of the bottled non-carbonated water was significantly more common among bacteriologically confirmed cholera cases than among paired controls.

In August 1974, six cases of cholera occurred on Guam. The index case had severe diarrhea and metabolic acidosis and died from pneumonia on the ninth day of illness; the other five cases had only mild to moderate diarrhea. Fish caught in Agana Bay and home-preserved was found to be the vehicle most likely responsible for the cases. Vibrio cholerae, El Tor Ogawa, was isolated from two patients, the Guam sewerage system, and a river emptying into Agana Bay. V. cholerae, El Tor Inaba, was isolated from the sewerage system, three storm drains imptying into Agana Bay, and Agana Bay. The Ogawa and Inaba isolates differed in their sucrose fermentation and hemolysis reactions, phage type and ability to produce toxin. Although this was the first reported cholera outbreak on Guam, the isolation of differentV. cholerae strains suggested that multiple introductions of V. cholerae had occurred on the island.

A double-blind controlled field trial of live, oral, streptomycin-dependent Shigella sonnei vaccine was begun in an institution with endemic S. sonnei disease. Considerable unexpected child-to-child transmission of the vaccine strains inadvertantly caused the field trial to resemble a mass vaccination campaign. Although S. sonnei accounted for 90% of shigella infections from 1968 to 1971 and three-fourths of the cases occurred in the seven study cottages, S. sonnei disease disappeared following vaccination; epidemiologic features suggest a causal relationship. Clinical S. sonnei disease did not occur despite the detection by bacteriologic surveillance of carriers of virulent S. sonnei. Levels of hygiene remained compatible with transmission of shigella since 43 cases of S. flexneri 6 were seen. If the interpretation is correct, the disappearance of S. sonnei disease resulted from inadvertent "mass vaccination" and oral shigella vaccines may prove useful for control of endemic shigellosis institutions. Nevertheless, a properly designed controlled field trial, taking into account transmissibility of vaccine, in an institutional setting similar to Sunland is necessary to substantiate the role of oral shigella vaccines in control of institutional shigellosis.

In the 10 years 1964-1973, 105,832 isolations of shigellae were reported to the Center for Disease Control through a nationwide surveillance system. The number reported increased by approximately 13% annually, from 5852 in 1964, when only 17 centers reported all 4 quarters; to 16,797 in 1973, when 52 centers reported each quarter. The rate of reported isolations varied from 4.6 per 100,000 persons in 1965 to 9.1 per 100,000 in 1973. Shigella sonnei accounted for 64% of all these isolates and for more than 80% of isolates in 1973. The majority of reported cases of shigellosis occurred in young children and in women of childbearing age. During the 10-year surveillance period, 35 epidemics in 25 states were investigated. Two-thirds of these outbreaks were the result of person-to-person spread; investigations of common-source outbreaks showed the importance of both water and foodstuffs, especially salads, as potential vehicles of contamination. Indian reservations, custodial institutions, and day-care centers were identified as special high-risk settings for the transmission of shigellosis. The emergence of R-factor-mediated antimicrobial-resistance patterns in recent years has necessitated antibiotic sensitivity testing to determine the drug of choice for treatment of individual cases. Initial testing of oral vaccines suggests these vaccines will have only limited usefulness in protecting certain high-risk populations. Public health education coupled with improvements in water and sewerage systems remains the most satisfactory means of control.

Diarrhea has been recognized as a frequent health problem among children enrolled in day-care centers. Thus, we evaluated the effect of a handwashing program in two day-care centers (HWC) on the incidence of diarrhea among children when compared to children in two control centers (CC). After the program was begun, the incidence of diarrhea at the HWC began to fall and after the second month of the study was consistently lower than that at the CC. The incidence of diarrhea in the HWC was approximately half that of the CC for the entire 35-week study period. Adenoviruses, rotavirus, Giardia lamblia, and enteropathogenic Escherichia coli were found in the stools of a small number of ill children, but not pathogen was identified in the stools of most children with diarrhea. These results suggest that a handwashing program will probably prevent at least some of the diarrhea in day-care centers.

In the United States between 1970 and 1974 there was an increase each year both in the absolute number of foodborne diseases outbreaks of chemical etiology reported to the Center for Disease Control and in the proportion of these outbreaks in the total reported foodborne disease outbreaks. Nearly half (48.9%) of these foodborne disease outbreaks of chemical origin were caused by toxic fish or shellfish. Of the rest, 16.5% were caused by poisonous mushrooms, 10.9% by heavy metal poisoning, 7.2% by excessive use in food of monosodium glutamate (the etiologic agent of Chinese Restaurant Syndrome) and 16.5% by miscellaneous chemicals. Practices that contributed to the occurrence of these outbreaks included the inadvertent selection for consumption of toxic fish, shellfish, or mushrooms, storage of fish at improper temperatures, storage of acidic liquids in metal containers, and addition of excessive amounts of monosodium glutamate to foods. Commercially-processed foods were responsible for outbreaks of scombroid fish poisoning, shellfish poisoning, and heavy metal poisoning. Because outbreaks of chemical etiology due to contaminated commercial products do occur, prompt recognition and reporting of outbreaks to public health personnel are essential so that epidemiologic investigations can be conducted and effective control measures promptly initiated.