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Virulence of Rickettsia prowazeki for head lice
Abstract:
Wild head lice were obtained by combing out adult and instar lice from the uncut hair of school children. Normal body lice were selected from a colony of rabbit-adapted body lice obtained from the United States Department of Agriculture and maintained in the Department of Microbiology for more than 10 yr. Thirty-nine head lice and 60 body lice were fed on a rabbit that had been injected intravenously with a 10% suspension of a yolk sac pool from eggs heavily infected with the Ankara strain of virulent R. prowazeki. Five days after infection, 33 body lice and 16 head lice had survived and were feeding on a volunteer. Between Days 5 and 9, 13 head lice were dead or moribund and all of them were positive by IF for R. prowazeki. The three surviving head lice were also positive. Tests on the 33 body lice showed that 22 were positive for R. prowazeki, including four of the five body lice that survived until Day 15. In summary, head lice can be readily infected with R. prowazeki and disseminate virulent R. prowazeki organisms in their feces. Thus, theoretically, head lice appear to be highly potential as transmitters of R. prowazeki under optimal epidemiologic circumstances.
Insights
Head lice can be infected with Rickettsia prowazeki and spread the bacteria in their feces. This finding suggests head lice could potentially transmit epidemic typhus under certain conditions.
Area of Science:
- * Infectious Diseases
- * Parasitology
- * Epidemiology
Background:
- * Rickettsia prowazeki (R. prowazeki) is the causative agent of epidemic typhus.
- * Body lice (Pediculus humanus humanus) are the primary vectors of R. prowazeki.
- * The role of head lice (Pediculus humanus capitis) in R. prowazeki transmission is less understood.
Purpose of the Study:
- * To investigate the susceptibility of head lice to R. prowazeki infection.
- * To determine if infected head lice can disseminate R. prowazeki.
Main Methods:
- * Head lice and body lice were experimentally infected with R. prowazeki.
- * Infected lice were fed on a rabbit and then on a human volunteer.
- * Infection in lice was confirmed using immunofluorescence (IF) assays.
Main Results:
- * Head lice were successfully infected with R. prowazeki.
- * Infected head lice disseminated R. prowazeki in their feces.
- * A significant proportion of both head lice and body lice tested positive for R. prowazeki.
Conclusions:
- * Head lice are susceptible to R. prowazeki infection.
- * Head lice can disseminate virulent R. prowazeki.
- * Head lice have the potential to transmit R. prowazeki under specific epidemiological conditions.