1921
Volume 14, Issue 1
  • ISSN: 0002-9637
  • E-ISSN: 1476-1645
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Abstract

Summary

Fourth-instar larvae of were infected with four group A (eastern equine encephalitis, western equine encephalitis, Venezuelan equine encephalitis and Sindbis) and four group B arboviruses (West Nile, St. Louis encephalitis, Japanese B encephalitis and dengue). Larvae of were infected with EEE and WN viruses. The imagoes of infected larvae were able to transmit these viruses by bite to suitable experimental animals. Ability to transmit WN virus was retained to the end of a 45-day test period.

The threshold doses required to infect larvae with viruses belonging to group A were higher than for viruses belonging to group B.

No virus could be detected in larvae 24 hours following exposure to WN virus. Virus was later detected first in the head and alimentary tract, and before pupation it was present in all parts of the larvae. The virus continued to multiply in the pupae and reached a peak titer in the adults on the day of emergence or a day thereafter.

Mosquitoes infected as larvae transmitted WN virus when they fed for the first time between the fourth and fifth day after emergence. It is questionable whether this represents the actual extrinsic incubation period because the levels of virus in the salivary glands were theoretically sufficient to elicit transmission even earlier.

The rates of transmission by infected in the larval stage ranged between 22% and 33% when the larvae were exposed to a suspension containing 3 × 10 to 3 × 10 LD of WN virus per ml.

The virus content of the ovaries, irrespective of the age of mosquitoes, was always low and in some cases not detectable.

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/content/journals/10.4269/ajtmh.1965.14.158
1965-01-01
2017-11-22
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