Ebba Lund

Survival and movement of enterovirus in connection with land disposal of sludges

Abstract Coxsackievirus and tritiated water were added to municipal sludges which were placed on lysimeters containing sandy soil or clay soil. It took 23 weeks during a normal Danish winter to inactivate virus from an initial 10 6 tcid 50 /g sludge to a not demonstrable level. Irrespective of sludge and soil type no virus was demonstrated in the leachate water. The rainfall during December–May was 300 mm.

The survival of enteroviruses in aerated and unaerated cattle and pig slurry

Abstract In an experimental system, where 80-litre tanks of pig or cattle liquid manure were kept at 5°C or 20°C, aerated or non-aerated, the tanks were seeded with various pathogens. This paper deals with the inactivation of enteroviruses. A pronounced effect of aeration on the rate of inactivation was found. A strong dependence on temperature was demonstrated under non-aerated conditions. Extreme values were thus found for porcine enterovirus. A decrease of one log unit of infectious virus was obtained at 20°C under aerated conditions in 2–4 days, whereas a one log unit decrease at 5°C under non-aerated conditions took 300 days.

The effect of sludge digestion on virus infectivity

Abstract The rate of inactivation of coxsackievirus B3 during anaerobic sludge digestion was found to be 2 log units in 24 h at pH 7.0 and 35°C. The rate indicates that virus inactivating factor(s) were produced in the digestion. The virus inactivation was enhanced if the digester sludge was pasteurized at 60°C for 1 h. The reason why digesters at sewage treatment plants do not completely inactivate virus is discussed in terms of the continuous nature of digester operation.

On the isolation of virus from sewage treatment plant sludges

Abstract Sludges from biological and chemical treatments of urban sewage were examined for virus. Virus was found bound to particles and was not eluated at pH 9·0 in the samples from activated sludge treatment. The secondary sludge contained less virus than the primary sludge. Treatment with lime, ferric chloride and aluminum sulfate in experimental scale removed virus from raw sewage so that virus could be demonstrated in the sludge from sewage where virus was not demonstrated. No virus inactivation in the chemical sludges were observed.

The stability of bovine parvovirus and its possible use as an indicator for the persistence of enteric viruses

Abstract Bovine parvovirus 1 (Haden virus) gives with grown in 0–24 h secondary cultures of calf kidney a pronounced CPE. The virus is very thermoresistant, it takes e.g. at 60°C 6 h to decrease the titer of infectivity 1 log unit. When seeded in liquid manure the virus becomes inactivated at a rate of around 6–8 days for 1 log unit under aerobic conditions at 5–20°C. The inactivation under anaerobic conditions is very temperature dependent: at 5°C it takes about 200 days to decrease the titer 1 log unit, but at 20°C a rate of inactivation of 20 days per log unit of virus was found. It is suggested that the bovine parvoviruses may be useful as indicators in connection with evaluations of the importance of viral bovine faecal pollution. For evaluations of treatment efficiencies it is suggested that these parvoviruses may also be used as indicators for human enteric viruses like the virus of infectious hepatitis.

Low technology water purification by bentonite clay flocculation as performed in Sudanese villages; virological examinations

Abstract Viruses were removed from various types of water by flocculation with natural bentonite clays from the banks of the Nile as well as with pure bentonite. The flocculation technique employed corresponds to that used to clarify Nile water in Sudanese villages. If proper flocculation occurred 3 to 4 log10 units of virus could be removed. Some of the conditions for floc formation were examined.

The effect of pretreatments on the virus contents of sewage samples

Abstract By isolations of virus from sewage and sludge samples, which had been fractionated by centrifugation at 9000 rev min -1 , it was found that virus may be particle bound and recoverable in the precipitates. An exception was the secondary sludge of the activated sludge treatment. It was thus indicated that removal of a part of a sewage or sludge sample before examination may make true quantitative estimations impossible. Re-examination of samples after storage at −20°C for 6 months gave remarkably poor virus recoveries.

INVESTIGATIONS IN CHILDREN WHO WERE IN UTERO AT ONSET OF INSULIN-DEPENDENT DIABETES IN THEIR MOTHERS

55 children who were in utero when type 1 diabetes developed in their mothers were studied at a mean (SEM) age of 10.4 (0.6) years: only 1 was diabetic. Biochemical and immunological indices, measured in 35 children, showed no evidence of beta cell dysfunction. Thus, the fetal beta cells seem to be unaffected by the mechanisms that cause diabetes in their mothers.