RESUMO
Thin-layer chromatography was used to study neutral lipids in snail-conditioned water (SCW) fromBiomphalaria glabrata snails. A major lipid fraction in SCW at 2 and 4 hr after snail incubation contained free fatty acids. Fatty acids released per snail per milliliter of water when 10 snails were incubated in 5 ml of deionized water for 4 or 2 hr was 2.4±0.4 µg/ml and 0.9±0.1 µg/ml (mean ± SE), respectively. The amount released at 4 hr was significantly greater than at 2 hr. Snails also released free sterols, a sterol ester-hydrocarbon fraction, methyl esters, and other unidentified lipid fractions into the water. The potential of these neutral lipids to serve as chemoattractants for larval trematodes or snails remains to be determined.
RESUMO
Eighty cases of typhoid fever occurred in San Antonio, Texas, with dates of onset from August 18, 1981, to October 26, 1981. Preliminary epidemiological investigations of the first 24 cases suggested a Mexican food takeout restaurant as the common source. A case-control study confirmed this association (P less than or equal to .001). Barbacoa , a mixture of muscle, lips, ears, tongue, and eyes from steamed bovine heads, was identified as the source of Salmonella typhi (P = .03). S typhi was cultured from the stool of one of 31 restaurant employees. Closure of the restaurant resulted in termination of the outbreak within a single incubation period. The restaurant was allowed to reopen after the remaining employees had demonstrated lack of excretion of S typhi in stools. This outbreak represents the largest restaurant-associated typhoid fever outbreak reported in the United States in greater than 50 years.
