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Persistent Infection

Chlamydial researchers have long thought that long term (chronic) or repeated chlamydial infection might make chlamydial-related disease worse. According to the Oxford English dictionary, persistent means either "enduring obstinately" or "constantly repeated". In practice, as far as chlamydiae are concerned, it is virtually impossible to distinguish obstinately enduring chronic chlamydial infection from acute, constantly repeated infections. However, there is lots of evidence that all of the well studied chlamydial species are capable of causing "enduring" infection for months or even years in the absence of treatment. 

Classic studies by Moulder in the early 1980s suggested that persisting chlamydial infection might be associated with incomplete chlamydial development, which, in turn, may be induced by products of the host immune response (notably gamma interferon). Alternatively as John Pearce suggested, it might be induced as a result of chlamydiae lacking some essential amino acids, such as tryptophan, essential for full chlamydial development. How well these in vitro models really hold up in vivo is unclear.

The key clinical question is, does "enduring" infection lead to the intermittent appearance of disease? This seems likely, but there is very little convincing information for the reasons given above.

[MEW] May 2002

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