The microbiome of dwarf chameleons

The microbiome of dwarf chameleons

by Alex Negro Tiermedizin Science

The term microbiome has been very popular for some years now. In humans and animals, it refers to the totality of all microorganisms that colonise a living being. Most of them colonise the gastrointestinal tract. In the case of chameleons, there is only very limited literature on this topic. A master’s thesis from South Africa now deals with the bacterial composition of the microbiome in South African dwarf chameleons of the genus Bradypodion.

60 cheek swabs were collected from wild chameleons in KwaZulu-Natal. Of these, 20 were cheek swabs from Bradypodion melanocephalum, 20 from Bradypodion thamnobates and 20 from Bradypodion setaroi. After sampling, the same 60 animals were transported in cloth bags to the research base, where the animals were kept in 3.3 l boxes for 24 hours to obtain faecal samples. Since not all of the original 60 chameleons defecated, faeces were collected from additional chameleons.

The samples were all genetically tested. 40.43% of the samples contained Firmicutes, a similarly large proportion of the samples contained Proteobacteria with 36.86%. Bacteroidota followed with some distance, which could be detected in just under 16% of the samples. Verrucomicrobiota, Fusobacteriota, Actinobateriota, Spirochetes, Desulfobacteroa, Cyanobacteria, Thermoplamatota, Deferribacterota, Synergistota, Campylobacterota, Deinococcota, Halobacterota, Euryarchaeota, Elusimicrobiota and Myxococcota were found in significantly smaller numbers (up to 2%).

The microbiome of dwarf chameleons of the species Bradypodion melanocephalum, Bradypodion thamnobates and Bradypodion setaroi is similar to that of other reptiles. It consists mainly of proteobacteria and firmicutes, which may contribute to digestion. One particular bacterial species also suggests that the diet of the studied dwarf chameleons may include beetles of the genus Dendrophagus. The microbiome of all three dwarf chameleon species was very similar in the cheek swabs – this is called phylosymbiosis – while there were differences in composition between the species in the faeces. In all three dwarf chameleon species, significantly more different bacteria were found in the faeces than in the cheek swabs. A comparison between males and females did not reveal any significant differences in the microbiome of all three chameleon species. The author assumes that the bacterial species depend on the different habitats of the respective species. It is still unclear to what extent the microbiome is related to bacteria that a chameleon may ingest with feeding insects or from the soil of its environment. A detailed list of the bacterial species found can be found in the appendix of the publication.

The Hitchhiker’s Guide to dwarf chameleons (Bradypodion): The composition and function of the microbiome
Matthew G. Adair
Master of Science dissertation at the university of Johannesburg, 2023
DOI: not available

Zoonotic potential of Yemen chameleons in Gran Canaria (Spain)

Zoonotic potential of Yemen chameleons in Gran Canaria (Spain)

by Alex Negro Science

The Canary Islands are located northwest of Africa near the coast of Morocco. On Gran Canaria, the second largest island, around 290 of over 1000 plant and animal species have been introduced, i.e. species that do not originally occur there. Since at least 2017, there have been free-living Veiled chameleons (Chamaeleo calyptratus) on Gran Canaria. Spanish scientists have now investigated whether this introduced chameleon population could have zoonotic potential.

They examined 40 Veiled chameleons that had previously been caught and killed by Red de Alerta Temprana de Canarias para la Detección e Intervención de Especies Exóticas Invasoras in Arucas. 36 of the chameleons were adults, four were juveniles. Intestinal contents were taken from each chameleon and analysed for the presence of different bacteria using various methods.

At least one of the bacteria sought was found in 28 of the Veiled chameleons. About half of the chameleons had Yersinia enterocolitica, which is the highest prevalence ever recorded for this bacterium in reptiles. The bacterium can cause diarrhoea in humans, among other things. It is unclear how the Veiled chameleons became infected with it – possibly via insects. 16 of the Veiled chameleons had salmonella in their intestines. Salmonella is very common in reptiles and has even been found in endemic species on Gran Canaria. Pseudomonas is also frequently found in reptiles and was detected in the intestines of 13 animals. Two Veiled chameleons were infected with Campylobacter, in one of them Campylobacter lari could be identified. This bacterium can rarely cause illness in humans, but no pathogenic potential for humans is known for the species otherwise common in reptiles. Campylobacter lari has so far been detected mainly in seafood and birds – it is possible that the Veiled Chameleons picked up the bacterium on the coast and did not bring it with them. Three Veiled chameleons had Escherichia coli, which in rare cases can lead to haemolytic uraemic syndrome (HUS) in humans. Another two chameleons had Listeria monocytogenes in their intestines, which can be dangerous for pregnant women if ingested with food. Five Veiled Chameleons had mycobacteria, several of which were found to be non-tuberculous infections. Staphylococci were detected in seven chameleons, but they are part of the normal skin flora. However, five isolates were positive for resistance to certain antibiotics, which is becoming an increasing problem with Staphylococcus aureus in humans. Most recently, Vibrio was detected in a single Yemen chameleon, some species of which can cause diarrhoea in humans. The bacterium has previously been detected in introduced anoles on Tenerife.

The authors state that there is a zoonotic potential for humans due to the handling of introduced Veiled Chameleons on Gran Canaria. However, the extent to which there is a real risk for humans as well as endemic species needs to be further investigated.

Study of zoonotic pathogens in alien population of Veiled Chameleons (Chamaeleo calyptratus) in the Canary Islands (Spain)
Román Pino-Vera, Néstor Abreu-Acosta, Pilar Foronda
Animals 13 (14), 2023
DOI:  10.3390/ani13142288