1921
Volume 9, Issue 2
  • ISSN: 0002-9637
  • E-ISSN: 1476-1645
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Abstract

Summary and Conclusions

The findings gathered in this investigation are summarized as follows:

  • a)  The and readily ingested and organisms on plate cultures and could even ingest small amounts of Coxsackie and Echo viruses in a fluid suspension.
  • b)  About 5 to 6% of the ingested or and about 12 to 16% of the ingested or Coxsackie A9 virus survived for 24 hours; but the survivals of these were reduced to about 0.1% and 1% respectively after 48 hours. There was no evidence of excretion of viable pathogens.
  • c)  These nematodes are so highly resistant to the destructive action of free chlorine in water that they were not affected by 2.5–3.0 ppm of chlorine in a 120-minute exposure or by 15 to 45 ppm of chlorine in a 1-minute exposure when the water temperature was 25° C, pH 6.6–7.2, and the chlorine residuals were only slightly lower than initials. Even with an initial chlorine as high as 95–100 ppm, 50–60% of these nematodes survived a 5-minute contact and 10–20% survived a 15-minute contact. The appeared to be somewhat more resistant than the , but the difference was reduced as the chlorine dosage was increased from 15 to 95–100 ppm.
  • d)  The ingested pathogens were protected by the carrier nematodes to the extent that they had a complete survival even when about 90% of the worms were immobilized by the free chlorine.

It is concluded that nematodes of the Rhabditidae family and of sewage-treatment origin may be potential carriers of human enteric bacteria and viruses. Although a majority of the ingested pathogens may disappear in 1 to 2 days after ingestion, 5 to 16% may remain viable if the worms are carried to the water supply within 24 hours after departure from their habitat and will survive routine chlorination as practiced in the field.

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/content/journals/10.4269/ajtmh.1960.9.136
1960-03-01
2017-11-24
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