Public health risks involved in the human consumption of reptile meat - Scientific Opinion of the Panel on Biological Hazards

Occurrence, Antimicrobial Resistance, and Virulence Profiles of Salmonella Serovars Isolated from Wild Reptiles in South Africa

Reptiles are carriers of an array of microorganisms, including significant zoonotic bacteria of the genus Salmonella, which cause a disease referred to as salmonellosis that affects both animals and humans. This study investigated the occurrence of Salmonella serovars in wild reptiles at Timbavati Private Game Reserve in Limpopo Province, South Africa, and examined their virulence and antimicrobial resistance gene profiles. A total of 19 wild reptiles were sampled, which resulted in 30 presumptive Salmonella isolates. The isolates were identified using polymerase chain reaction (PCR) by amplifying the invA gene and were further confirmed by 16S rRNA gene sequencing. Salmonella serovars were detected in chameleons (36.8%), lizards (31.6%), snakes (15.8%), and tortoises (15.8%). The use of 16S rRNA gene sequencing revealed that Salmonella enterica subsp. enterica serovar Salamae (30%), S. enterica subsp. enterica (16.7%), S. enterica subsp. enterica serovar Typhimurium (13.3%), and S. enterica subsp. enterica serovar Indiana (13.3%) were the four most common subspecies among the investigated 30 isolates. Detected virulence genes included pagN (100%), hilA (96.7%), ssrB (96.7%), prgH (86.7%), and marT (86.7%). The isolates exhibited resistance to nalidixic acid (43.3%) and kanamycin (43.3%), followed by streptomycin (16.7%) and ciprofloxacin (3.3%). Antibiotic-resistant genes were detected as follows: strA, strB, qnrA, qnrS, parC, aadA, aac(6')-Ib, and aac(6')-Ib-cr at 33.3%, 6.7%, 16.7, 13.3%, 10%, 23.3%, 6.7%, and 10%, respectively. The findings highlight the necessity of educational initiatives aimed at reducing reptile-related infections. Effective antibiotic treatment appears promising for infection, given the minimal drug resistance observed in reptile Salmonella serovars in the current study.

Eustrongylides spp. parasite risk management in Atherina boyeri from Lake Trasimeno

Atherina boyeri is the primary source of fishing profit in Lake Trasimeno and a common host for Eustrongylides spp. larvae. The presence of Eustrongylides in fish is a public health concern, and effective risk management procedures are necessary to guarantee that infected products do not reach the market. Currently, in the European Union, there is no official sampling plan for fresh fish that defines sample size, inspection methods, and criteria for accepting or rejecting the product. An approach to Eustrongylides risk management is proposed in this study. A total of 270 batches of A. boyeri, each consisting of 29 specimens, were collected and examined visually in 3 years (2020-2023). The prevalence of the parasite was 20% in 2020, and in the first months of 2021, it grew up to ⁓40%, then dropped to 12.50% in December 2021 and settled at 16% in February 2022. In January and February 2023, the prevalence fell below 1%. The mean abundance was calculated and used to establish a threshold value to determine fish marketability. In 2020 and 2021, several batches were judged not marketable, and in some batches, a freezing treatment was implemented to ensure the inactivation of the parasite. In the last months of 2022 and in January and February of 2023, the presence of parasites in captured fish was negligible, and this allowed the marketability of fish as fresh. The proposed sampling plan was effective in preventing the commercialization of potentially hazardous products.

The first reptilian allergen and major allergen for fish-allergic patients: Crocodile β-parvalbumin

BACKGROUND

Clinical cross-reactivity between bony fish, cartilaginous fish, frog, and chicken muscle has previously been demonstrated in fish-allergic patients. In indicative studies, two reports of anaphylaxis following the consumption of crocodile meat and IgE-cross-binding were linked to the major fish allergen parvalbumin (PV). This study investigates IgE-binding proteins in crocodile meat with a focus on PV and their clinical relevance.

METHODS

Proteins were extracted from muscle tissue of crocodile, three bony fish, and two cartilaginous fish. A cohort of fish-allergic pediatric patients (n = 77) underwent allergen skin prick testing (SPT) to three fish preparations (n = 77) and crocodile (n = 12). IgE-binding proteins were identified and quantified by SDS-PAGE, mass spectrometric analyses, and immunoblotting using commercial and in-house antibodies, as well as individual and pooled patients' serum. PV isoforms were purified or recombinantly expressed before immunological analyses, including human mast cell degranulation assay.

RESULTS

Of the tissues analyzed, PV was most abundant in heated crocodile preparation, triggering an SPT of ≥3 mm in 8 of 12 (67%) fish-allergic patients. Seventy percent (31 of 44) of fish PV-sensitized patients demonstrated IgE-binding to crocodile PV. Crocodile β-PV was the major IgE-binding protein but 20-fold less abundant than α-PV. Cellular reactivity was demonstrated for β-PV and epitopes predicted, explaining frequent IgE-cross-binding of β-PVs. Both PV isoforms are now registered as the first reptile allergens with the WHO/IUIS (β-PV as Cro p 1 and α-PV as Cro p 2).

CONCLUSION

Fish-allergic individuals may be at risk of an allergy to crocodile and should seek specialist advice before consuming crocodilian meat.

Optimization and Implementation of the Virus Extraction Method for Hepatitis E Virus Detection from Raw Pork Liver

Hepatitis E virus (HEV) has been frequently detected from pork liver and liver products, which can usually cause self-limiting diseases in healthy adults, yet may result in fatality in immunosuppressed groups. Nevertheless, there is so far no standardized method for HEV detection available from pork liver and/or liver products. The present study aimed to optimize the virus extraction method of HEV from raw pork liver, which is often consumed in Asia undercooked to avoid a grainy texture. By comparing different sample preparation protocols and by applying the selected protocol to 60 samples collected from Singapore retail markets, we demonstrated that homogenization of 0.25 g raw pork liver with FastPrep™ Lysing Matrix Y containing yttria-stabilized zircondium oxide beads in 2 ml tubes and with harsh mechanical force at 6 ms^-1, 40 s/cycle, for 5 cycles with 300 s pause time after each cycle is promising in both releasing the potentially intracellular viruses and resulting in satisfactory virus recovery rates (> 1%). A high prevalence (52%) of HEV genome was detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) from the 60 samples collected from Singapore retail markets imported from Indonesia, Australia and Malaysia. However, RNase treatment decreased the HEV prevalence to 33.3%, and all of the 20 positive samples were with high RT-qPCR Ct values above 35, suggesting that the positive RT-qPCR signals maybe largely due to the inactive viruses and/or exposed HEV RNA traces in raw pork liver products. Therefore, conscious care should be taken when interpreting molecular detection results of viruses from food samples to be correlated with public health risks.

Zoonotic Parasites of Reptiles: A Crawling Threat

Reptiles are reservoirs of a wide range of pathogens, including many protozoa, helminths, pentastomids, and arthropod parasitic species, some of which may be of public health concern. In this review we discuss the zoonotic risks associated with human–reptile interactions. Increased urbanization and introduction of exotic species of reptile may act as drivers for the transmission of zoonotic parasites through the environment. In addition, being a part of human diet, reptiles can be a source of life-threatening parasitoses, such as pentastomiasis or sparganosis. Finally, reptiles kept as pets may represent a risk to owners given the possibility of parasites transmitted by direct contact or fecal contamination. Awareness of reptile-borne zoonotic parasitoses is important to advocate control, prevention, and surveillance of these neglected diseases.

Species of protozoa, helminths, pentastomids, and arthropod vectors exploit reptiles as definitive or paratenic hosts, which may represent a public health concern.

The zoonotic risk is associated with human–reptile interactions and includes environmental contamination, reptile consumption, or keeping reptiles as pets.

Exotic reptile species may introduce new zoonotic parasites in a previously nonendemic region.

Pentastomiasis and sparganosis are life-threatening food-borne parasitoses.

In our households, if precautions are not taken, reptiles may transmit zoonotic parasites by direct contact or fecal contamination.

Trained veterinarians, physicians, and public health officials are important to advocate for proper diagnostics, parasite identification and treatment, as well as for surveillance strategies and food inspection in areas where reptiles are consumed.