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Endoparasites Infected 71.2% of Tropical House Geckos in Western Pará

Tropical house gecko photographed in French Guiana
Research: Disease, parasites & microbiology, Ecology

Tropical house geckos living around towns and homes in western Pará, Brazil, carried a diverse community of internal parasites. Researchers examined 156 wild tropical house geckos (Hemidactylus mabouia) from urban and peri-urban sites and found endoparasites in 111 animals, or 71.2% of the sample.

The gecko is native to sub-Saharan Africa but has become established across much of the Americas, where it commonly lives on buildings and feeds on insects and other small arthropods. That generalist diet can repeatedly expose it to parasites whose life cycles pass through invertebrate intermediate hosts.

Six parasite taxa and 1,819 individuals

The researchers collected geckos between January 2024 and November 2025 in Belterra, Mojuí dos Campos and Santarém in Pará. After measuring the animals, they examined the digestive tract, lungs, liver, gallbladder and body cavity for metazoan endoparasites.

In total they recovered 1,819 parasites belonging to six taxa spread across five major groups: nematodes, acanthocephalans, cestodes, trematodes and pentastomids. Individual geckos usually carried only a few parasite taxa at the same time. Across the sample, infections were strongly aggregated, meaning that parasites were concentrated in some hosts rather than being distributed evenly among all geckos.

The trematode Paradistomum sp. was the dominant parasite. It occurred in 37.8% of the geckos and accounted for much of the parasite abundance. It was found mainly in the gallbladder, bile duct and intestine, and heavily infected gallbladders were visibly enlarged. The study did not test what physiological effects this enlargement had on the geckos. The small intestine contained the largest number of parasites overall, followed by the gallbladder and bile duct.

Parasite patterns differed among localities

The same broad set of parasite groups occurred across the study area, but infection levels differed between sites. At the peri-urban Belterra site, Paradistomum occurred in 70.0% of geckos, compared with 9.4% at the urban Belterra site. In the urban areas of Belterra and Santarém, the pentastomid Raillietiella sp. instead reached prevalences of about 34–35%.

These contrasts show that human-modified environments did not produce one uniform parasite community. The study documented substantial local variation in which parasites were most prevalent, but did not directly test what caused those differences.

Larger geckos carried more of most parasite taxa

Body size was linked to parasite abundance. Larger geckos carried more individuals of five of the six parasite taxa tested, while Paradistomum showed no such relationship. Because snout–vent length generally increases with age in these lizards, the researchers interpret the pattern as consistent with larger and older animals accumulating exposure over time and consuming more prey.

Females had a numerically higher infection prevalence than males, 76.2% versus 60.8%, but the study did not find clear statistical support for a sex difference in the probability of infection. The result therefore does not show that females are intrinsically more susceptible.

A new host record in South America

The study also recorded cystacanths of the acanthocephalan genus Centrorhynchus in tropical house geckos for the first time in South America. Cystacanths are an infective larval stage of thorny-headed worms. Their presence shows that the invasive geckos have become incorporated into local parasite life cycles in the eastern Amazon.

Taken together, the results show that an introduced reptile closely associated with people can host a substantial and locally variable parasite community. Rather than remaining isolated from native parasite networks after its introduction, the tropical house gecko appears to have become part of them.

Sources and image credit

  1. Santos-Cruz, A. B., Chagas-de-Souza, D., Alves-Coêlho, T., et al. (2026). Parasitic fauna in the invasive lizard Hemidactylus mabouia (acertilia: ekkonidae), in anthropized environments of eastern Brazilian Amazon. Urban Ecosystems, 29, Article 275.Primary open-access research article; version of record first published 26 September 2026 under CC BY 4.0. Full text checked. Researchers examined 156 wild tropical house geckos from urban and peri-urban sites in western Pará, Brazil; 71.2% were infected and 1,819 endoparasites from six taxa were recovered.

Image: Tropical house gecko (Hemidactylus mabouia) at Hotel Lac Maran, Matoury, French Guiana, 1 March 1998. Photo: Bernard DUPONT / Wikimedia Commons. CC BY-SA 2.0. Representative image; not a study animal. · CC BY-SA 2.0 · Source

About this content: This story was produced with AI assistance within an editorial workflow developed by Wildlife Vagabond. Editorial responsibility remains with Wildlife Vagabond.How AI is used

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