Molecular and biological characterisation of Cryptosporidium in pigs

OBJECTIVE: Genetic and biological characterisation of 12 isolates of Cryptosporidium from pigs and comparing them with Cryptosporidium isolates from humans and cattle. DESIGN: Cryptosporidium isolates from pigs were compared with those obtained from human and cattle using rDNA sequence analysis. The infectivity of two of the porcine isolates was determined in neonatal mice and the clinical history of the infected pigs recorded. RESULTS: Pig-derived isolates of Cryptosporidium exhibited two distinct genotypes; a porcine genotype and a bovine genotype, which is common to cattle and other livestock. The porcine genotype did not produce any infection in neonatal mice whereas the bovine genotype did. CONCLUSION: Two distinct genetically and biologically differing strains of Cryptosporidium appeared to be associated with acute diarrhoea in pigs. Whether Cryptosporidium was a primary or secondary pathogen is unclear but warrants further investigation. As the bovine genotype is known to infect humans, the results suggest that pigs can act as reservoirs of cryptosporidial infections for humans and other live-stock. The zoonotic potential of the pig-adapted genotype is uncertain and requires further study.     

Movement of dieldrin through soils: II.—In sloping troughs and soil columns

A glass-lined trough was divided into six compartments by vertical transverse partitions and filled with soil to a height of 5 cm above the top of each partition. The base of the box and the surface of the soil sloped forwards one end with a gradient of 1 in 3·7. Dieldrin was applied (22 kg active ingredient/ha) to the soil surface in the uppermost compartment and the movement of dieldrin into leachate and down the slope was followed for 17 weeks. During this time 19·5 cm of rain fell. Less than 0·02% of the dieldrin appeared in the leachate and 99% of this was collected during the first 9 weeks, mainly from the uppermost compartment. Very little dieldrin moved down the slope and it was not detected in the leachate from compartments other than the treated one during 9–17 weeks after treatment. In other experiments, 3 cylinders were filled respectively with sandy loam, heavy clay loam and peat which were transferred from the field as intact cores. Three other cylinders were filled with soils of the same types but broken up. Approximately 2% of the dieldrin leached through one column but usually it was much less than 0·1%. The largest amounts of dieldrin were leached down columns of heavy clay loam, intermediate amounts down columns of peat, and least through sandy loam. Ten times as much dieldrin leached down the columns of intact soil as through those with broken soil. The results indicate that the movement of dieldrin from treated soil into water systems by leaching is limited and is unlikely to be a major pathway for the contamination of water.     

Pesticide residues in foodstuffs in Great Britain: XIII.—Organochlorine residues in cereals,pulses and nuts

Results are presented for the determination of organochlorine insecticide residues in grain, pulses and nuts sampled on arrival in Britain during the 2½ years up to June 1969. BHC was detected in nearly every sample but the general level was low, most samples containing less than 0·1 ppm. DDT was found less frequently. Very few samples contained more than 1 ppm of either insecticide. DDE in trace amounts was found in about 10% of the samples of grain and nuts and TDE was found in one sample of grain. The only other organochlorine compounds detected were aldrin in one sample of pulses and hexachlorobenzene in 7 samples of wheat.