C. ibidis: a new species of Chlamydia discovered by ANSES's Laboratory for Animal Health

Avian chlamydiosis is a disease caused by C. psittaci, a parasitic bacteria that affects over 465 species of domestic, farmed and wild birds. This pathogen can infect humans, causing a severe form of pneumonia which can be fatal in sensitive individuals when it is not diagnosed or treated in time.  The most highly exposed individuals are those in direct contact with birds, such as farm, slaughterhouse and veterinary personnel.

Birds and poultry that are healthy carriers of C. psittaci are commonly found in the poultry sector.

The recent work conducted by the NRL has led to the discovery of new species of Chlamydia, in  chickens, pigeons and the African sacred ibis.

A new strain of Chlamydia discovered in the African sacred ibis

The African sacred ibis has been imported to numerous zoos throughout the world.  In the 1990s, a group of ibises escaped from a wildlife park in Brittany. This highly invasive species rapidly multiplied, settling along the Atlantic coast. This population, which now counts over 5000 individuals, is a major ecological problem for native animal biodiversity as well as a potential health issue as a reservoir for pathogens.

Since this ibis had been sighted in contact with farmed ducks, which have a high prevalence of C. psittaci, the NRL, in partnership with a team from Nantes, conducted a study in order to determine whether these wild birds might be carriers of the pathogenic bacteria and if they might pose a risk to open-air farms.

Unexpected discovery of a new species

Analyses conducted on 70 sacred ibises revealed that 8 individuals were carriers of Chlamydiaceae. Contrary to expectations, only one of the birds was a carrier of C. psittaci, the pathogen which is generally isolated in birds. The 7 other birds were carriers of a Chlamydia strain with atypical characteristics. In collaboration with an American and a German team, the full sequencing of the genome of the incriminated strain was performed and an electron microscope image was made, confirming that these atypical Chlamydia strains did correspond to a new species, baptised C. ibidis.

To date, no proof has been found regarding the pathogenicity of C. ibidis. Additional studies will now need to be conducted to expand our understanding of this new species.

Questions to be resolved by ANSES

This discovery raises a number of questions which have yet to be answered. Firstly, it would be useful to determine the geographical origin of the infection by these new strains of Chlamydia: were the sacred ibises infected in Africa, their region of origin, or in France after they were imported?  Is this bacteria found in the environment? Can it infect other bird species, or other animals in general?  Lastly, monitoring of the zoonotic nature (possibility of transmission to humans) of this new species is needed, which if proven could pose a public health problem. The answers to these different questions will enable ANSES to conduct a risk assessment of this new species.