Cryptosporidiosis is a globally important protozoan disease that causes severe gastrointestinal illness in immunocompromised humans and animals and has been associated with chronic wasting and death in reptiles. This study investigated the role of Cryptosporidium infection in wasting syndrome among captive leopard geckos from a commercial breeding facility in Chiang Mai, Thailand. Thirty-five geckos housed in twenty-three enclosures were observed for four months, with fecal samples collected over three consecutive days every two weeks and pooled for molecular analysis. Clinical evaluations included body weight (BW), tail diameter, and body condition score (BCS) to assess wasting. Nested PCR targeting the 18S rRNA gene and subsequent sequencing were performed. Cryptosporidium was detected in 51.43% of geckos and 52.17% of enclosures, while 20% exhibited wasting syndrome. BLAST (v. 2.17.0) and phylogenetic analyses identified C. varanii, which showed 100% identity with isolates from leopard geckos in Spain and from snakes in Thailand and China. Multivariable logistic regression demonstrated a significant association between Cryptosporidium infection and wasting syndrome (OR = 11.15, 95% CI: 1.78–69.98, p = 0.027), with persistent oocyst shedding observed. This study provides new insights into C. varanii infection among leopard gecko breeders in Thailand and highlights the potential for infected breeding stock to disseminate Cryptosporidium, underscoring the need for enhanced awareness, surveillance, and biosecurity measures across Thailand and the Asia-Pacific region.

The tiger (Panthera tigris) is an apex predator and plays a fundamental role in sustaining biodiversity through its native range in Asia. By controlling populations of large herbivores and mesopredators, tigers help maintain the structural integrity of habitats, thereby supporting a diverse array of flora and fauna. Despite its ecological importance, the tiger is one of the most threatened large carnivores globally. It is classified as Endangered on the IUCN Red List, although threat categories vary among subspecies, and it is listed in Appendix I of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), which covers all tiger subspecies. Over the past two decades, global tiger populations have declined by more than 90%. Consequently, they have become the focus of conservation efforts, including captive breeding and reintroduction initiatives. However, the reintroduction of captive-bred tigers into natural habitats presents significant scientific and logistical challenges. This review synthesizes current knowledge on the complexities of using captive tigers for reintroduction programs, with particular attention to welfare and behavioral competence of captive individuals, and genetic diversity and health of founder populations. It further addresses critical considerations for habitat suitability and managing potential human-tiger conflict and evaluates the overall effectiveness and feasibility of tiger reintroduction as a conservation strategy.