Gastrointestinal parasites in feral cats and rodents from the Fernando de Noronha Archipelago , Brazil

Gastrointestinal parasites are important pathogens affecting animals, some of them are of medical and veterinary concern. Although the dynamic of parasitic infections is a complex phenomenon that has been studied under experimental conditions, it shows several gaps in knowledge, especially in insular regions where a confined population of animals and parasites co-exists. In this study was assessed the parasitism by endoparasite gastrointestinal in feral cats (n = 37) and rodents (n = 30) from the Fernando de Noronha Archipelago; in addition, the risk of human infection and ecological implications of these findings were discussed. Out of all samples analysed, 100% scored positive for the presence of gastrointestinal parasites in both feral cats and rodents. A total 17 genera and/or species of endoparasite gastrointestinal were identified, Ancylostoma sp., Strongyloides sp., Trichuris campanula and Toxocara cati were the parasites more frequently in feral cats. In rodents Eimeria sp., Strongyloides sp. and Trichuris muris were parasites more frequently herein detected. Human population living in this area are at risk of parasite infections due to the population of rodents and feral cats in the archipelago.


Introduction
Gastrointestinal parasites are important pathogens affecting animals and humans throughout the world (BLAGBURN et al., 1996;DEPLAZES et al., 2016).According to the World Health Organization (WHO), approximately 3.5 billion of people are affected by these parasites every year, being 450 million children who present clinical manifestations (OKYAY et al., 2004).Among animals, cats and rodents are considered important reservoirs for a wide range of zoonotic parasites.For example, cats may harbour several species of gastrointestinal parasites (e.g., Ancylostoma tubaeforme, A. brasiliensis, Toxocara cati and Toxoplasma gondii), and shed their immature stages through the faeces, contaminating the environment (BALASSIANO et al., 2009;COSTA et al., 2012;BEUGNET et al., 2014;MONTEIRO et al., 2016;SARAVANAN et al., 2016).
The transmission cycle of gastrointestinal parasites is influenced by several abiotic and biotic factors, which impact on their abundance into a given environment (MONTEIRO et al., 2016).Accordingly, the availability of infective stages in a highly contaminated habitat enhances the chance for paratenic (e.g., rodents) and accidental (e.g., humans) hosts to be exposed to the pathogens (THOMPSON & CONLAN, 2011).
In these circumstances, understanding the dynamic of the infection is essential to plan control strategies.Besides experimental activities in controlled-laboratory conditions, the dynamic of the infection by parasites has been poorly studied in select areas, such insular regions, where confined animal population animals and pathogens may show a different behaviour.For instance, studies on gastrointestinal parasites in cats and rodents at the Fernando de Noronha Archipelago are scarce, although this archipelago has suffered over the last years from anthropic modification, which took to the introduction of exotic animal species, including cats and rodents (COSTA et al., 2012).Recently, few studies have been conducted in this area with T. gondii (SILVA et al., 2017), however lack information to others gastrointestinal parasites.
Therefore, because the scarce of data about gastrointestinal parasites and their implications on animals living in Fernando de Noronha Archipelago, the aim of this study was to assess the parasitism by gastrointestinal parasites in feral cats and rodents.

Ethical aspects
This study approved by the Instituto Chico Mendes de Conservação da Biodiversidade -ICMBio (licence number 48994-3) and performed following the current legislation of the Brazilian College of Animal Experimentation.

Study area
The study was performed on August 2016 in the middle of winter of the Fernando de Noronha Archipelago (3°50'24" S and 32°24'48" W).The area is formed by the main island and other 21 secondary islands comprising a total area of 26 km 2 .The main island has about 3000 inhabitants, but every year may host until 50.000tourists (IBGE, 2010).The local ecosystem is comprised by several native and exotic species of birds, reptiles, mammals, marine animals and several non-native species of arthropods.
Conversely, samples of cats were obtained after spontaneous defecation.A total of 67 faecal samples were collected, 37 from feral cats (Felis catus) and 30 from rodents (Rattus rattus, n = 25; Kerodon rupestris, n = 05).All samples were conserved into plastic tubes containing 10% formalin solution until laboratory evaluation.Each sample was individually analysed through the FLOTAC technique (CRINGOLI et al., 2010).All cysts, eggs, oocysts and larvae were identified based on morphological features provided in Bowman et al. (2006) and Taylor et al. (2010).

Data analysis
Data were analysed by using the software InStat (GraphPad Software), with a significance level of p<0.05.

Discussion
This study investigated, for the first time, the presence of gastrointestinal parasites in rodents and feral cats living at the Fernando de Noronha Archipelago, Brazil.
Data indicate that the level of parasitism in these "exotic" animals is higher than that observed in other studies performed in other insular areas (THOMPSON & CONLAN, 2011).For instance, a prevalence of 53.5% (15/28) and 76% (76/100) were documented in feral cats from Christmas (Australia) and Baleares (Spain) islands (ADAMS et al., 2008;RAAB et al., 2016), whereas a positivity of 46.2% (30/65) was reported in rodents from the Santa Catarina island (Brazil) (KUHNEN et al., 2012).This suggests that animals living in the study areas are exposed to a high infective pressure.
Worthy of note, the majority of the parasite detected in this study are of medical concern (e.g., Ancylostoma sp. and T. cati), representing a threat for the public health.For example, Ancylostoma sp. were recorded in cats from Brazil (THOMPSON & CONLAN, 2011), causing cutaneous Larva migrans syndrome in humans (BOWMAN et al., 2010).Another important parasite that deserves attention due the risk for humans are those of the Toxocara cati observed in this study in feral cats, and considered the responsible for visceral larva migrans (VLM), ocular Larva migrans (OLM) and cerebral Toxocariasis in humans (DESPOMMIER, 2003;FAN et al., 2015).
In addition, it is important to highlight the detection of Hymenolepis nana and Taenia sp.parasitizing rodents and humans, all of them of medical and veterinary concern (MOLINARO et al., 2009;GALAN-PUCHADES, 2015), were helminths that parasitize humans, which may cause diarrhea, abdominal pain, irritability and weight loss (MUEHLENBACHS et al., 2015).
On the other hand, G. duodenale causes serious problems to host health, due to the appearance of enteritis, which trigger enzymatic and morphological changes in intestinal loops (SMITH et al., 2007).It is interesting to note that based on molecular and phylogenetic evidence, G. duodenale is part of a complex genetic group, with genotypes A and B accounting for more than 80% of human infections (RYAN & CACCIÒ, 2013).
In the present study, the sharing of parasites among different hosts suggests this phenomenon and may have important implications on the risk for human infections.For instance, data herein reported demonstrated the sharing of some parasite species, particularly, Entamoebidae among rodents, and humans, since data of the Surveillance Service of the island recorded frequently the parasitism by Endolimax nana in human native residents.
The presence of parasites on these hosts from the island may be a result of ecological events and their early introduction in this environment by conquestors.However, their perpetuation is favoured by several determinants factors such as inadequate facilities and inappropriate basic sanitation.Therefore, people living in this area are at risk of parasite infections due to the population of feral cats and rodents in the archipelago.

Table 1 .
Gastrointestinal parasites in the fecal samples of feral cats and rodents from Fernando de Noronha archipelago, Brazil.