A cholera outbreak associated with eating uncooked pork in Thailand.

In a village near Chiangmai, Thailand, during October 1987, there was an outbreak of cholera following a funeral in which 264 attendants were served food. The present article is a report of an epidemiological study performed to identify the source of infection and the mode of its transmission. All the attendants were screened for infection by bacteriological examination of their rectal swabs and were kept under diarrhoeal surveillance. Of them, 20 patients and 40 matched controls were interviewed about the details of their eating foods served at the funeral. Vibrio cholerae 01, Inaba, El Tor was detected from 24 persons (9.1%), 15 of whom suffered from mild diarrhoea and the rest 9 had inapparent infections. There was no death. Except one butcher whose rectal swab was positive for the same strain of V. cholerae, 3 other butchers and 4 women who had prepared food were free from the infection. Food remnants were not available for culture. The water used for cooking and the water from the cement well used for slaughter were negative for the organism. The only significant association (p less than .01, odds ratio = 15) was found between an attack of cholera and eating laebmoo--an uncooked pork preparation with Thai spices and chili. The transmission of cholera appeared to have occurred through eating the uncooked pork presumably due to its contamination with V. cholerae shed by the infected butcher. He was known to have earlier visits to Chiangmai where cholera epidemic was going on.

Several sporadic outbreaks of El Tor cholera in Sunpathong, Chiang Mai, September-October, 1987.

From September through October 1987, a cholera outbreak involving 59 cases of biotype El Tor, serotype Inaba occurred in Sunpathong district, Chiang Mai. No cases died. Twenty-seven cases were males and 32 were females. The age ranged between 4 months and 85 years, with a median of 36 years. The outbreak affected 7 small communities, and showed different vehicles of infection. Six housewives and one girl were infected with cholera in the first localized outbreak. The transmission of infection appeared due to the consumption of packed food contaminated by an infected food handler. In the second localized outbreak, 6 young males acquired cholera after eating uncooked fish harvested from a canal contaminated with cholera organisms. Another outbreak of cholera with 24 culture-confirmed cases occurred among guests at a funeral held in one rural village. The source of infection was traced to uncooked pork contaminated from an infected butcher: Early detection of infected persons, rapid identification of possible vehicles of transmission, and prompt implementation of control measures effectively curtailed the extension of these outbreaks.

Surveillance of diarrhoeal diseases in Thailand.

PIP: To provide information for prevention and control activities at national and local levels, Thailand's Ministry of Public health has monitored trends for diarrheal diseases since 1970. Data for the 1978-83 period obtained from the national epidemiological surveillance system are reported. The data were collected largely through a passive surveillance network in each province of Thailand. After preliminary analysis and tabulation at the local level, data were sent to the Ministry of Public Health for further analysis. Details on each case of diarrheal disease included the age, sex, place of residence, date of onset, and place of treatment. 5 categories of diarrheal diseases were distinguished: cholera, enteric fever, food poisoning, dysentery, and acute diarrhea. The causative agents of diarrheal diseases generally were isolated and identified in provincial hospital laboratories or at a government regional laboratory. During the 1978-83 period, 1,979,118 cases of diarrheal diseases were reported to the Thai Ministry of Public Health through the national surveillance system. The annual number of cases increased from 175,411 in 1978 to 537,972 in 1983, and this is reflected in an increase in the annual incidence from approximately 400/100,000 population in 1978 to over 1000/100,000 population in 1983. The average annual incidence of diarrheal diseases reported over this period was 694/100,000 or approximately 330,000 cases per annum. The number of cases of all categories of diarrheal disease increased, except cholera, which fluctuated from year to year. Acute diarrhea exhibited the highest average annual incidence (537/100,000), followed by that of dysentery (85), food poisoning (43), and enteric fever (25). Cholera had the lowest incidence (4/100,000). Over the 6-year study period, the majority of cases reported were acute diarrhea (77.4%), followed by dysentery (12.2%), food poisoning (6.3%), and enteric fever (3.5%). Cholera accounted for 0.6% of cases. A total of 3300 deaths from diarrheal diseases were reported over the study period. Deaths in each disease category, except cholera, decreased, and the annual number of deaths declined from 911 in 1978 to 370 in 1983. Acute diarrhea was the most common category leading to death. For acute diarrhea, the highest age-specific mortality rate was among children aged 0-4 years. Age-specific mortality rates for the remaining disease categories were much lower. The highest mean incidence rate for reported cases of acute diarrhea occurred in the central region of Thailand (608/100,000).^ieng