# MURINE TYPHUS:  VECTOR BIOLOGY AND TRANSMISSION

> **NIH NIH R01** · UNIVERSITY OF MARYLAND BALTIMORE · 1988 · $127,513

## Abstract

Although murine typhus occurs in diverse habitats in many parts of the
world and has been an important cause of human disease in certain areas,
there still are many unexplained features about the vector biology and
transmission of this zoonosis, especially since a variety of ectoparasites
and small mammals are deeply involved.  In this study we will continue to
use modern quantitative methods to examine, under controlled conditions in
the laboratory, selected components and inter-relationships of the
pathogen-vector-host complex.  As has been shown by the results to date,
such information can contribute to our understanding of the encology of
murine typhus; for example, we have provided evidence indicating that cat
flea (Ctenocephalides felis) and the rat flea Leptopsylla segnis should be
regarded as potential vectors.  For the first time, transovarial
transmission of the infection to the next generation of fleas has been
demonstrated.  This finding raises the possibility that fleas may serve to
perpetuate the cycle of murine typhus infection in nature.  Data are
provided suggesting that murine typhus may perhaps be transmitted by the
bite of the flea, and not merely by contact with feces or tissues of
infected fleas.  Such observations may change our concepts about the
transmission of this rickettsiosis and hence affect recommendaions for its
control.  Our objectives include:  1) to investigate in detail the
quantitative interactions between Rickettsia mooseri including means of
transmission and the course of infection in four species of fleas
(Xenopsylla cheopis, Ctenocephalides felis, Leptopsylla segnis and
Echidnophaga gallinacea) and the rat losue (Polyplax spinulosa); 2) to
study host immunological responses to flea infection which may affect the
acquisition and transmission of R. mooseri; and 3) to study the reservoir
mechanisms including vertical transmission in fleas and reactivation of
latent infection in rats, using natural stress such as pregnancy and
parasite or immunosuppressive drugs such as cyclophosphamide.

## Key facts

- **NIH application ID:** 3127458
- **Project number:** 5R01AI017828-07
- **Recipient organization:** UNIVERSITY OF MARYLAND BALTIMORE
- **SAM.gov UEI:** Z9CRZKD42ZT1
- **Principal Investigator:** Abdu F Azad
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1988
- **Award amount:** $127,513
- **Award type:** 5
- **Project period:** 1982-09-01 → 1990-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3127458

## Citation

> US National Institutes of Health, RePORTER application 3127458, MURINE TYPHUS:  VECTOR BIOLOGY AND TRANSMISSION (5R01AI017828-07). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3127458. Licensed CC0.

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