A DNA probe for the detection of Dicrocoelium dendriticum in ants of Formica spp. and Lasius spp.

Repetitive DNA sequences present in the genome of Dicrocoelium dendriticum were identified by hybridization of genomic DNA that had been digested with different restriction enzymes with 32P-labeled genomic D. dendriticum DNA. DNA fragments containing repetitive sequences were isolated from PstI-digested D. dendriticum DNA and were subcloned into a plasmid vector. Plasmids containing repetitive sequences were identified by colony hybridization. One of these plasmids, designated Ddr-IV, was isolated and used as a probe in further studies. Ddr-IV is specific for D. dendriticum since it does not hybridize to DNA isolated from other trematodes. In addition, Ddr-IV was capable of detecting D. dendriticum metacercariae in ants (Formica cunicularia, F. rufibarbis, and Lasius sp.), which act as second intermediate hosts in the parasite's life cycle. Since metacercariae constitute the infectious stage of the parasite for grazing animals, Ddr-IV will provide a useful tool for epidemiology studies of dicrocoeliosis.

Somatic antigens of adult Dicrocoelium dendriticum recognised by bile antibodies of naturally infected cattle.

Bile samples, from slaughtered cattle harbouring between 120 and 280 adult lancet flukes, were used to investigate the range of somatic proteins inducing local antibody responses in naturally infected animals. Lancet fluke infections induced local (bile) antibody responses against Tris-buffered saline (TBS) soluble, sodium dodecyl sulphate (SDS) soluble and 2-mercaptoethanol (2-Me) soluble somatic proteins of adult Dicrocoelium dendriticum. IgA antibody isotypes predominated in the response against buffer-soluble somatic antigens, whereas SDS-soluble and 2-Me-soluble proteins induced similar level of both IgA and IgG1 antibodies. Analysis of the antigens recognised by particular isotype-specific bile antibodies suggests that different antigens preferentially induce isotype restricted antibody responses. The bile antibody response was highly species specific, only one antigen from somatic protein extracts of Fasciola hepatica being precipitated by bile samples showing the highest reactivity against D. dendriticum.

An update of respiratory cancer and occupational exposure to arsenicals.

Mortality was updated through 1982 for 611 arsenic-exposed employees originally studied through 1973. In the earlier report, total mortality was observed to have been below the comparable U.S. population; however, mortality was significantly elevated for respiratory cancer. The focus of the update was on respiratory cancer and of special interest was whether the risk of respiratory cancer remained in excess for individuals alive as of the end of the last study. In the update, 9 additional respiratory cancers were observed subsequent to 1973, the end of the follow-up in the original study, versus 7.8 expected. The risk ratio for the time-interval 1974-1982 (standardized mortality ratio SMR = 116) was diminished compared to that reported in the original study (SMR = 330). When the entire study period was analyzed, the risk of respiratory cancer did not appear to decline with interval since exposure cessation. Analyses by duration of arsenic exposure and interval since first exposure did not reveal any obvious dose-response relationships.