The guinea pig (Cavia porcellus) is bred worldwide either as a laboratory model or a pet (1). Native to the Andean region of the Americas, guinea pigs are raised for ceremonial events and livestock in Colombia, Ecuador, Peru, and Bolivia (2). Guinea pig farming modalities vary from backyard breeding in groups of a few animals per household for family consumption to larger establishments with thousands of animals for commercial purposes (3). Only in Ecuador, at least 710,000 families are involved in guinea pig farming, with an estimated annual production of 50 million animals that are destined for sale and family consumption (4). Moreover, guinea pig breeding as livestock has been recently introduced in some African countries, such as Cameroon and Benin (5, 6). Despite its importance to the local rural economy, breeding is still performed mainly in a traditional manner. Lack of veterinary counseling or animal health-specific guidelines are usual, compromising food safety (3, 4).

The status of guinea pigs as zoonotic reservoirs is well known, given their frequent use for experimental infections as laboratory animal models, as well as pets (3). However, this knowledge remains very limited for guinea pigs raised as livestock (3). Several zoonotic pathogens have already been identified in livestock guinea pigs, including respiratory pathogens such as influenza virus, antibiotic-resistant Staphylococcus aureus and Streptococcus pneumoniae, as well as yeasts (7–10). Also enteric pathogens like Campylobacter jejuni (11), and Toxoplasma gondii have been described (12, 13). Additionally, several studies have shown the role of guinea pigs as zoonotic reservoirs for enteric parasites (6, 14–17). Most of these studies were conducted in Ecuador and Peru, reporting a high prevalence of protozoan parasites, including Giardia, Blastocystis, Entamoeba, Eimeria, and Cryptosporidium, as well as several species of helminths (14–17). Moreover, a study carried out in Cameroon has reported a high prevalence of Giardia, Cryptosporidium, and helminths in livestock guinea pigs (6), as well.

Enteric parasites, including helminths and protozoans, are significant contributors to the global burden of disease, particularly in rural, low-income settings in tropical regions such as Ecuador (18). In these endemic areas, chronic parasitic infections during childhood have a strong link with stunting, the most common form of malnutrition in children, affecting physical growth and cognitive impairment (18). Moreover, the protozoan parasites Cryptosporidium spp., Giardia duodenalis, and Entamoeba histolytica are relevant diarrhea-causing pathogens globally, transmitted fecally either directly through contact with infected humans and other animals or indirectly via the ingestion of contaminated food or water (6, 18). Although the carriage of these parasites has already been reported in guinea pigs, the role of guinea pigs as a reservoir for enteric pathogens is still poorly understood.

Despite the importance of guinea pig farming for rural communities in the Andean Region, there is an important gap of knowledge related to infectious diseases affecting guinea pig production and public health. Thus, we aim to study the prevalence of protozoan and helminth parasites in livestock guinea pigs from Ecuador and to identify the potential risk factors related to animal production practices on this species.

In the present study, a remarkable prevalence of 86% for enteric parasites in guinea pig farms from Ecuador was found, including five genera of protozoa and seven of helminths already described as zoonotic parasites in domestic animals. Moreover, mixed infections with two or more parasites were also persistent in guinea pigs. While the most prevalent protozoan parasite was Eimeria, with a prevalence of over 50%, other important zoonotic protozoans, such as Giardia and Cryptosporidium, were also found. Three zoonotic helminths were also found at prevalences over 10%: Fasciola hepatica, Trichostrongylus, and Trichuris. Overall, our results align with previous studies in Ecuador, Peru, Cameroon, and Benin, where the carriage of enteric parasites in livestock guinea pigs has already been reported (5, 6, 14–16). Moreover, various studies in Ecuador have shown that gastrointestinal parasitosis is a problem shared by different animal species, which allows the findings in guinea pigs to be put into context. For instance, the prevalence of helminths reached 27.4% and 74.32 in free roaming dogs from rural and urban settings in Ecuador, respectively (23, 24). In cattle, high infections rates of 87.3% and 31% for protozoa and helminths (31.0%) have been reported in Chimborazo province (14); an also an overall high parasitism rate of 82.44% have been reported in sheep (25), and 48.65% in backyard pigs (26). Our findings in guinea pigs support these pervious reports underscoring a widespread presence on enteric parasites across different species of domestic animals in Ecuador.

To the best of our knowledge, our study is the first report of F. hepatica in guinea pigs from Ecuador. In fact, there is only a single report from 1996 where F. hepatica was described in guinea pigs from Peru (27). This zoonotic parasite causes fasciolosis, a neglected disease in South America, which is associated with severe hepatic disease (28, 29). Human fasciolosis outbreaks have been reported in Ecuador (28), and animal reservoirs, including cattle, sheep, and pigs, have been previously identified (29). Our results support that guinea pigs may also play a role as reservoirs of F. hepatica in in the Andean region.

The zoonotic parasites found in our research have substantial implications for public health. For instance, Eimeria, Giardia, and Cryptosporidium are well-known agents that cause diarrhea, and helminths such as Trichuris also cause gastrointestinal problems (6, 18, 30). In general, these enteric parasites are involved in the burden of disease in rural settings from low- and middle-income countries like Ecuador, including child malnutrition and stunting (18). Moreover, cryptosporidiosis as a foodborne zoonosis of veterinary and public health concern more associated to small livestock like guinea pigs (30). In this sense, guinea pig backyard production was analyzed as one of the categories in the variable type of farm. Although backyard production was not found to be a risk factor for parasitism, the high level of parasites prevalence represents a public health threat. In the context of the Andean region, this guinea pig backyard production includes a very traditional breeding in indigenous communities where the animals grow in the kitchen area within the household in a very close interaction with food, kitchen stuff and humans itself. Public policies dedicated to rise awareness in managing parasitic infections would help to prevent transmission to humans, as it has been suggested for other domestic animals in close contact with humans like horses (31).

The impact of basic guinea pig breeding parameters on the level of enteric parasitism in guinea pigs was assessed in this study to the best of our knowledge. In these sense, three risk factors were found in the multivariate analysis. First, the type of cage used for guinea pig breeding had an impact on the prevalence of parasitism, with “poza” having a smaller prevalence compared to “jaula”. Although the accumulation of fecal residues (meaning a higher risk for parasite exposure) is expected to be larger over the dirt ground in “poza” than in “jaula”, the results could be explained by the fact that the “poza” is cleaned more frequently compared to the “jaula” (reported by producers to the authors). Second, feeding guinea pigs exclusively on fresh forage was also associated with a higher prevalence of parasitism in guinea pigs compared to balanced feed supplementation, which may be linked to a better immune status link to the balance feeding; but also to the fact that fresh forage came from pastures also use to feed cattle and contamination with fecal material (and parasites) happened. Third, the prevalence of parasite infection was higher in guinea pigs exposed to other domestic animals like dogs, cats, pigs or cattle, underscoring transmission of parasites across domestic species due to the panzootic nature of these pathogens. Nevertheless, we draw attention to the prevalence of parasitism, which was generally high. Still, the differences in risk factors analyzed indicate that sanitary interventions would have an impact that warrants further research and standardization. In this sense, other control measures and ethnoveterinary approaches could also be considered in guinea pig farming, as its has already been reported for sustainable parasite control in small livestock like poultry (32, 33).

Our study has some limitations that we would like to acknowledge. First, as a convenience sampling was used, potential bias cannot be totally rule out, and either overall parasitic prevalence values and risk factor analysis should be taken with caution; further studies involving larger animal samples and farms for more provinces of Ecuador should follow. Second, our diagnosis was based in traditional morphological identification under the microscope without confirmation by molecular methods; further studies should include molecular diagnosis to improve the sensitivity and specificity of the parasites species identified, as it has already been done in small ruminants (34, 35).

In conclusion, our study highlights the guinea pig as a reservoir for zoonotic enteric parasites in Ecuador. Those findings underscore the need for further research with a One Health perspective to enhance livestock guinea pig health and productivity. This field of study is fundamental to developing effective practice guidelines for guinea pig farming, which will enhance production, mitigate occupational risks for breeders, and reduce foodborne transmission. This is particularly relevant in the context of rural Andean communities, where guinea pigs are part of the diet for millions of people, often in underserved communities, where food security is crucial in the fight against child malnutrition.