PREVALENCE OF TOXOPLASMOSIS ( TOXOPLASMA GONDII ) IN ECUADOR

Introduction: Toxoplasma gondii , the agent of toxoplasmosis, is a global zoonosis affecting mammals and birds, with the domestic cat as its definitive host. Discovered in 1980, it infects one-third of the human population and is transmitted through contaminated food or congenitally, causing various syndromes. Study Objective: To determine the incidence of Toxoplasma gondii in Ecuador during the period 2013-2023. Methodology: A comprehensive literature review of publications from January 2013 to December 2023 was conducted, selecting relevant scientific articles. Searches were carried out in databases such as Scopus, WOS, Google Scholar, SciELO, Dialnet, institutional thesis repositories, and EBSCO. Conclusion: Toxoplasmosis represents a major public health concern in Ecuador due to its high prevalence and associated risks. This necessitates regional preventive measures, such as food education and screening tests, due to the geographical and temporal variability of Toxoplasma gondii .


INTRODUCTION
Toxoplasma gondii is the causative agent of toxoplasmosis.The domestic cat is the definitive host closest to humans, where the parasite undergoes sexual reproduction and produces oocysts.Toxoplasmosis is a globally distributed zoonosis, with Toxoplasma gondii as its etiologic agent, a ubiquitous parasite that has infected at least one-third of the human population.It causes multiple syndromes, with felines as the definitive hosts and warm-blooded animals, including humans, as intermediate hosts (1).
The parasite Toxoplasma gondii was discovered in 1980 by Nicolle and Manceaux in Tunisia and Splendore in Brazil.The first report of what was likely a case of congenital toxoplasmosis was described by Janků in 1923, but it was not until 1939 that T. gondii was conclusively identified as a cause of pathology (2).
According to Opsteegh et al. (3), the initial classification of the genus Toxoplasma was based on the type of host.Thus, there were nine species: T. alencari, T. bahiensis, T. brumpti, T. colubri, T. gondii, T. hammondi, T. pardalis, T. ranae, and T. serpai.It was in the 1930s that the different biological cycles and immunological characteristics of the isolated parasites began to be compared, demonstrating that they were identical and were grouped under the same genus and species: Toxoplasma gondii.It is transmitted in two ways: acquired through the      Congenital: Occurs when a woman acquires parasitemia caused by Toxoplasma gondii during pregnancy.The proliferating forms infect the mother's body systemically and cross the placenta, increasing the risk of causing severe sequelae.(8; 9).
In this context, the objective of this study was to determine the incidence of the protozoan Toxoplasma gondii in Ecuador during the period 2015-2024.

METHODOLOGY
This study is the result of an exhaustive literature review conducted between January and March 2024, covering publications from January 2013 to December 2023.Various types of sources were included: 14 scientific articles from recognized databases such as SCOPUS, WOS, EBSCO, and Latindex; 14 undergraduate and postgraduate theses from university repositories; 3 official and state databases; and 1 health manual.In total, 56 documents were reviewed, of which 32 were selected for their relevance and informative contribution to the topic in question.
The initial search in the databases was conducted using the keywords: "Toxoplasmosis," "Toxoplasmosis in patients in Ecuador," "Toxoplasmosis in Felis catus," "Toxoplasma gondii," "cases of Toxoplasma in domestic animals in Ecuador."To obtain more precise data on the topic, terms such as "clinical cases of Toxoplasma gondii in humans and domestic animals" and "percentage of pathogen transmission in Ecuador" were included.This methodology allowed for the identification and selection of the most relevant and up-to-date studies that significantly contribute to the understanding of the topic addressed in this review.
For this literature review, three selection criteria were applied: Relevance: The scientific articles chosen for the research must be strictly related to the study topic.
Exhaustiveness: Certain articles were included in the search for information on clinical cases and infections caused by the parasitic protozoan in domestic animals and its impact on humans in the Ecuadorian region.The aim was to provide relevant information to readers, students, and researchers, particularly in veterinary medicine.

Range:
The scientific articles chosen were those that meet the criterion of being no less than 10 years old with updated information.Through the research, it was possible to identify the characteristics of the pathogenic agent causing toxoplasmosis and its incidence in domestic animals and humans in the different provinces of Ecuador.

GENERAL ASPECTS OF TOXOPLASMA GONDII
Toxoplasmosis is a prevalent zoonosis in tropical areas, affecting various animal species.The biological cycle of T. gondii includes oocysts, tachyzoites, bradyzoites, and tissue cysts that can remain indefinitely in the host (10; 11; 12).It is estimated that 70% of the human population in warm climates has been exposed to T. gondii (13).

Prevalence in humans
The prevalence of toxoplasmosis in humans varies considerably in Ecuador depending on environmental, socioeconomic and cultural factors, for which data published in recent years is referenced: In the city of Quito in 2015: In pregnant women, the prevalence was 40% (14).In the Central Sierra region in 2018: The prevalence in young women was 36% (15).In the Sierra Sur region in 2022: The prevalence was close to 30% (16).The compilation of various theses and research on the Amazon region revealed seroprevalence studies in three provinces: Morona Santiago, Sucumbíos and Pastaza.
Morona Santiago: The highest incidence rate was found, with a total of 5 infected people.
Pastaza: No patient with toxoplasmosis was found after the examinations carried out.
In figure 3, the mean prevalence of Toxoplasma gondii in humans in Ecuador shows significant variations both between regions and over the years:

Figure 2
Mean prevalence of Toxoplasma gondii in humans by region and year in Ecuador.suggests that exposure conditions to the parasite can change rapidly, necessitating sustained interventions.

Coastal
Inter-Andean Region: Presents a consistently high prevalence in different subregions and years, highlighting the persistence of infection risk in this area.
These variations indicate the importance of conducting continuous and specific studies to identify risk factors and implement appropriate prevention measures to control the prevalence of toxoplasmosis in different regions of the country.
There has been a reduction in the number of positive cases, which may be attributed to a general improvement in the sanitary conditions of the population, possibly influenced by measures adopted during the COVID-19 pandemic.
There are no recent records on the prevalence and incidence of the pathogen in humans in the last two years.

Guayaquil
At the University of Guayaquil, in 2020, it was determined that 26% of cats on campus had antibodies against T. gondii (19).Another study in the city found a seroprevalence of 5% in cats, with a distribution of 10% in indoor cats and 0% in outdoor cats (20).

Calceta
A study in 2022 found a prevalence of toxoplasmosis of 15.2% in cats, with a distribution of 8.8% in males and 6.4% in females.By age, 3.2% were between 1-6 months, 4.8% between 6 months-1 years, and 7.2% over 1 year (21).

Quito
In 2015, the prevalence of toxoplasmosis in domestic felines was 76% (22).In 2018, a seroprevalence of 27.2% was determined in samples obtained from three feline shelters (23).In 2017, a seroprevalence of 14% was found in cats of 30 cats in the Metropolitan District (24).
Another study in 2017 found a seroprevalence of 9.63% in cats sampled in veterinary clinics north of the capital (14).

Latacunga (Province of Cotopaxi)
In 2015, at the Planeta Vida Veterinary Hospital, it was found that 25% of felines presented antibodies against T. gondii (25).

Cuenca (Province of Azuay)
A study of Veterinary Medicine students at the Salesiana Polytechnic University, Cuenca, found a prevalence of 29.75% (16).

Ambato
For his part, Cousen Añasco (28) determined a seroprevalence of 26.8% (8/30) in cats that attended several clinics in the city.
In the Amazon Region, there is no data.

In the Island Region (Insular)
In the Galapagos, a 10-day-old specimen of Zalophus wollebaeki has been observed in captivity with toxoplasmosis.A case of disseminated toxoplasmosis was also reported in adult northern fur seals in the wild, where encephalitis caused by Toxoplasma gondii was found.The source of infection in these animals is intriguing, as marine mammals generally feed on coldblooded animals, in which T. gondii does not multiply.Oocysts can survive for some time in the sea and be concentrated by filter-feeding organisms.

Santa Cruz Island:
A study by the Agency for Regulation and Control of Biosafety and Quarantine for Galapagos (ABG) determined a prevalence of 50.90% (52/102) in pet cats (30).

Prevalence in Land Birds
Seropositivity in land birds ranged from 13% in Nazca gannets (Sula granti) to 100% in Galapagos mockingbirds (Mimus parvulus).Seronegativity was observed in all magnificent frigatebirds (Fregata minor) and swallow-tailed gulls (Creagrus furcatus).The prevalence decreased from occasional carnivores (63.43%) to granivores-insectivores (26.22%) and strict piscivores (14.62%), it is important to highlight the presence of the pathogen in birds since without many of the direct routes to contact with domestic animals such as cats (32).
Figure 4 shows the mean prevalence of Toxoplasma gondii in cats by region and year.

Coastal Region (Litoral):
The prevalence in this region is notably lower compared to the other regions and remains relatively stable in the years studied.This suggests a more controlled situation or less exposure to the parasite in this area.
Amazon Region: There are no reported prevalence data in this region, which represents a gap in information that could be relevant for a comprehensive understanding of the distribution of Toxoplasma gondii in Ecuador.
The prevalence of Toxoplasma gondii in Ecuador varies significantly between different regions and over the years.The Galapagos region consistently shows the highest rates, while the Coastal region presents the lowest and most stable rates.The Inter-Andean region exhibits considerable variability in prevalence, indicating the need for further studies to better understand the factors influencing these fluctuations.Continuous surveillance and implementation of specific prevention measures for each region are crucial to control the prevalence of toxoplasmosis in the country.11

CONCLUSIONS
Toxoplasmosis is a zoonotic pathology caused by the protozoan Toxoplasma gondii, which exhibits a high prevalence in various mammalian and avian species.The domestic cat is considered the primary host, playing a crucial role in the parasite's biological cycle.
Toxoplasmosis is a significant concern for public health in Ecuador, given its high prevalence and potential associated risks, especially for pregnant women and immunocompromised individuals.Implementing preventive measures, such as educating on safe food handling practices and ensuring access to timely detection and treatment tests, is crucial for reducing the burden of this disease in the Ecuadorian population.
The prevalence of Toxoplasma gondii in humans in Ecuador shows considerable geographic and temporal variability, with the Coastal region experiencing significant fluctuations between 2015 and 2017, while the Inter-Andean region maintains a consistently high prevalence in different subregions and years.
The insular region (Galápagos) exhibits a very high prevalence of Toxoplasma gondii in cats in the studied years (2013 and 2017), suggesting a high risk of zoonotic transmission, while the Coastal region shows lower prevalence in cats but remains significant in humans.

AUTHORS' CONTRIBUTION
Cinthia Ramos Grijalva: the author focused on the search and selection of relevant scientific articles in databases and institutional repositories, evaluated the quality of the studies, and participated in the analysis of the results.
Danilo Yánez: Led the general design of the study, supervised the search and selection process of relevant scientific articles.In addition, he participated in the analysis and interpretation of the collected data and in writing the manuscript.
Betty Lorena Vayas: she contributed her experience in epidemiology and public health to the analysis of the data collected and to evaluate the importance of the findings in the context of public health in Ecuador.She also participated in the interpretation of the results and in writing the conclusions section.
Andrés Mora Tola: Contributed his experience in the epidemiology of infectious diseases and animal health to understand the geographical and temporal distribution of Toxoplasma gondii in different regions of Ecuador.He participated in the analysis of data related to prevalence in humans and felines.

Figure 1
Figure 1Life cycle of Toxoplasma gondii ___________________________________________________________________________ Rev. Gest.Soc.Ambient.| Miami | v.18.n.8 | p.1-14 | e07394 | 2024.6 El Oro Province in 2016: In a study on IgG antibodies against T. gondii in pregnant women, 16% were found to be seropositive.Seropositivity was higher in the 20-25-year-old group, with 12% IgG positive and 10% IgM positive (17).In the city of Guayaquil in 2016: In a descriptive study on 72 patients with HIV/AIDS diagnosed with toxoplasmosis encephalitis, a prevalence of 8.8% was shown among admitted patients, with the group aged 30 to 39 years being the most affected (43.3%) (18).In other general studies carried out in the Coastal Region in 2017: The prevalence of toxoplasmosis was 50% (14); while years later in 2015: In people under 20 years of age, the prevalence was 74% (15).

Figure 3
Figure 3Mean prevalence of Toxoplasma gondii in cats by region and year in Ecuador