CLASSIFICATION

The species are subdivided into three groups of species according to the type of clinical disease they cause; typhus, spotted fever or scrub typhus. They are further subdivided according to host and arthropod vector.

BIOCHEMISTRY

They predominantly grow within cells, where they nevertheless follow the kinetics typical of bacterial growth. A number of types require increased CO2 levels. They apparently obtain their energy by exchanging internal ADP for external ATP. Glucose and other carbohydrates are not used but phophorylated compounds like uridine-5'-diphosphoglucose can be. Glutamate is a preferred substrate and be used as a source of ATP.

There is only limited information available. Genome sizes of around 1.40-2.0 mbp have been estimated. DNA-DNA hybridization studies have been used to determine the homogeneity of the species. Many spotted fever species would be considered on the basis of these studies as one species, they only differ on host range.

Both soluble and cell bound antigens have been used for serological differentiation. These may be extracted from cultures in yolk sacs. More recently immunofluorescence, ELISA, immunodifusion and Western blot assays have been developed. These are used both to determine the presence of specific anitigen as well as antibodies.

NORMAL FLORA

They may be part of the normal flora of arthropods.

Enteric Infections:
None.

Extraintestinal Infections:
Depending on the group, they are the cause of typhus, spotted fever or scrub typhus, which causes dissminated infections of mammals including humans.

Animal Infections:
Many vertebrate species are affected by them causing conditions like typhus, spotted fever or scrub typhus. The animals include rodents, birds, marsupials, dogs, cattle etc.

The isolation of rickettsiae is a specialised task, requiring tissue culture cells or animals.
Specific antibody tests, staining techniques are more frequently applied.
Indirect methods, such as antigen and/or antibody detection are the more common means of diagnoses as are new specific DNA detection methods.

They are not able to survive outside bodies of humans or animals

No industrial uses other than for the production of vaccines or identification kits have been reported.

Killed or attenuated live vaccines for epidemic and endemic typhus, Rocky Mountain spotted fever and scrub typhus have been available for many years. Recombinant DNA methods are now being investigated.

Rickettsiaceae

© Copyright Microbionet.

All literary matter in Microbionet is covered by copyright, and must not be reproduced, stored in a retrieval system, or transmitted in any form by electronic or mechanical means, photocopying, or recording, without written permission. This page is to be read in conjunction with the Disclaimer.

Use of this site signifes your agreement to the Legal Notices. Legal Notices © Copyright Microbionet. All rights reserved.