Louise M. McFarland

Cholera--a possible endemic focus in the United States.

In September and October 1978, after a case of cholera had been discovered in southwestern Louisiana, 10 more Vibrio cholerae O-Group 1 infections were detected in four additional clusters. All 11 infected persons had recently eaten cooked crabs from five widely separated sites in the coastal marsh, and a matched-triplet case-control study showed a significant relation between cholera and eating such crabs (P = 0.007). V. cholerae O1 was isolated from estuarine water, from fresh shrimp, from a leftover cooked crab from a patients refrigerator, and from sewage in six towns, including three without identified cases. All isolates in Louisiana and an isolate from a single unexplained case in Texas in 1973 were biotype El Tor and serotype inaba; they were hemolytic and of a phage type unique to the United States--suggesting that the organism persisted undetected along the Gulf Coast for at least five years.

Multi-State Outbreaks of Acute Gastroenteritis Traced to Fecal-Contaminated Oysters Harvested in Louisiana

Norwalk-like viruses (NLVs), or small round structured viruses, are known to cause acute gastroenteritis associated with eating contaminated shellfish. Between 1993 and 1996, three oyster-related gastroenteritis outbreaks attributed to NLV occurred in Louisiana. Intensive trace-back and environmental investigations revealed that the overboard disposal of sewage by oyster harvesters into oyster-bed waters was the most likely source of contamination in at least two of the outbreaks. The small infectious dose of NLV, the large quantity of virus particles in stool, and the ability of oysters to concentrate virus particles suggest that oyster-related outbreaks will continue unless strong control measures are established. Efforts to halt improper sewage disposal in oyster-harvesting waters, including overboard sewage discharge, must be undertaken if future outbreaks are to be prevented.

Cholera on a Gulf Coast Oil Rig

A single case of severe diarrhea on a floating Texas oil rig was followed two days later by what proved to be the largest outbreak of cholera in the United States in over a century. After isolation of toxigenic Vibrio cholerae El Tor Inaba of the typical United States phage type from the index patients stool, the ensuing investigation detected 14 additional cases of cholera and one asymptomatic infection serologically. Infection was associated with eating rice on the oil rig on a particular day (P = 0.03) when an open valve permitted the rigs drinking-water system to be contaminated by canal water containing sewage (including that from the index patient) discharged from the rig. The rice had been rinsed in the contaminated water after cooking, and before being served it had been maintained at a temperature that allows V. cholerae 01 to multiply. Toxigenic V. cholerae 01 is persisting in the United States, and large common-source outbreaks of cholera can occur if proper sanitation is not maintained.

Meningococcal disease in Louisiana 1978–1985

Data were analyzed from 729 meningococcal cases reported to the Epidemiology Section, Office of Preventive and Public Health Services, Louisiana Department of Health and Human Resources from 1978 through 1985. A total of 122 deaths (16.8%) occurred from these cases, with the highest case fatality rate (23.7%) noted in 1981. The eight-year average incidence rate per 100,000 population was 2.1. For individual years, the incidence rate was highest (3.6) in 1978 and lowest (0.8) in 1985. Although incidence rates per 100,000 population were greater for males during all years except 1978 and 1985 and greater for nonwhites in 1978, 1980, 1981, 1983 and 1984, the eight-year average incidence rates by sex and race were almost the same. Incidence rates were found to be highest in the less than one, and one to four-year age groups. For all eight years, over half of the cases were in the four years and under age group; the same was true for deaths, except in 1982 (46.7%). February was found to be the month with the highest frequency of reported case onset and death. The mean difference between date of disease onset and death for all fatal cases was 2.716 days (S.D.=6.48). Ten of the 64 Louisiana parishes reported no meningococcal disease cases from 1978–1985. There were 25 parishes with an eight-year average incidence rate of greater than 2.1. The overall incidence rates in Louisiana were greater than rates in the United States for the time periods reviewed.Data were analyzed from 729 meningococcal cases reported to the Epidemiology Section, Office of Preventive and Public Health Services, Louisiana Department of Health and Human Resources from 1978 through 1985. A total of 122 deaths (16.8%) occurred from these cases, with the highest case fatality rate (23.7%) noted in 1981. The eight-year average incidence rate per 100,000 population was 2.1. For individual years, the incidence rate was highest (3.6) in 1978 and lowest (0.8) in 1985. Although incidence rates per 100,000 population were greater for males during all years except 1978 and 1985 and greater for nonwhites in 1978, 1980, 1981, 1983 and 1984, the eight-year average incidence rates by sex and race were almost the same. Incidence rates were found to be highest in the less than one, and one to four-year age groups. For all eight years, over half of the cases were in the four years and under age group; the same was true for deaths, except in 1982 (46.7%). February was found to be the month with the highest frequency of reported case onset and death. The mean difference between date of disease onset and death for all fatal cases was 2.716 days (S.D.=6.48). Ten of the 64 Louisiana parishes reported no meningococcal disease cases from 1978–1985. There were 25 parishes with an eight-year average incidence rate of greater than 2.1. The overall incidence rates in Louisiana were greater than rates in the United States for the time periods reviewed.

Clinical and laboratory features of an outbreak of Vibrio cholerae O1 infections in the united states

A point source outbreak of Vibrio cholerae O1 El Tor Inaba infections occurred aboard an oil rig south of Port Arthur, Texas, in September 1981. Sixteen crew members had V. cholerae O1 infections as determined by serology or stool specimens; 15 were symptomatic. The high percentage of symptomatic infections was attributed in part to the ingestion of a large number of V. cholerae O1 organisms by susceptible individuals. Symptoms included diarrheal stools (100%), weakness (60%), abdominal cramps (53%), nausea (40%), and vomiting (27%). Only one of the three patients who sought medical attention was diagnosed by his physician as having cholera. Physicians who treat patients who live near or travel to the Gulf Coast should consider cholera in patients with watery stools. If cholera is suspected, laboratories should use thiosulfate-citrate-bile salts-sucrose (TCBS) agar in addition to routine enteric media for processing stool specimens.