Comprehensive Control of Toxocariasis in Communities

Abstract

With the purpose of understanding the complexity of actions aimed at controlling the main zoonotic soil-transmitted helminthiasis in the world, this book chapter is proposed around the comprehensive control of toxocariasis in urban communities. From the understanding of the epidemiological cycle implicit in the vertical transmission of parasites of the genus Toxocara in their main urban definitive hosts (canines and felines), an action that allows a “perpetuity” of the parasite in urban areas, passing through the inextricable relationships of synanthropic hosts until reaching their paratenic or accidental hosts, humans. At the same time, control strategies will be discussed in the various links of its transmission/infection chain, demonstrating that preventive medicine supported by selective strategic deworming in canines and felines within their various age ranges is the fundamental pillar in the fight against this parasitosis. Likewise, exploring the substantial advances in the development of vaccinology to integrate new strategies in the comprehensive control of toxocariasis in communities.

1. Introduction

Toxocariasis is the disease caused by parasites, type roundworms (nematodes, order Ascaridida) of the genus Toxocara; the etymology of the scientific name is Toxo = arrow + cara = head. The species Toxocara canis (Werner, 1782) and Toxocara cati (Schrank, 1788) [1], and possibly Toxocara vitulorum, Toxocara pteropodis, Toxocara malayasiensis, and Toxocara lyncus. These last four have a category of low level zoonosis to unresolved zoonotic potential [2, 3, 4].

The definitive hosts of T. canis and T. cati are canines and felines, particularly within urban communities’ domestic dogs and cats, respectively [5]. An adult female roundworm of dogs (T. canis) can lay 200,000 eggs a day, which are expelled in the feces of parasitized dogs. Over a period of 2–4 weeks, they embryonate in the environment, subsequently emerging as an infective larva (third-stage larvae, L3), which could accidentally parasitize humans (paratenic or accidental host); due to these characteristics, toxocariasis is the main zoonotic soil-transmitted helminthiasis in the world [6].

Humans are not the definitive host of Toxocara; therefore, the life cycle of this parasite is not fulfilled. What does occur is the development of various larva migrans syndromes, where L3 migrates from the intestine to various tissues, including the central nervous system (neurotoxocariasis), abdominal viscera (visceral larva migrans), and eye (ocular larva migrans) [7]. Also, a clinical presentation where patients in whom positive toxocara serology is associated with a number of systemic and localized symptoms and signs (notably abdominal pain) but not visceral or ocular larva migrans, called covert/common toxocariasis (CT) [8].

Remembering “The Iceberg Model” within the diagnosis of a problematic situation in public health, where only the tip of the iceberg (the observable cases of direct correspondence to the infectious agent) correspond to 10% of the true magnitude of the problem [9], we can understand the real importance of toxocariasis. Toxocara is associated with alterations in the immune system’s response to vaccines for various preventable infectious and contagious pathologies (e.g., rabies), in addition to a series of autoimmune diseases [10, 11, 12, 13, 14]. Additional studies indicate that CT may represent a major cause of lung dysfunction, cognitive disturbances, and intellectual deficits in children living in poverty [15]. Thus, toxocariasis is one of the causes of the cycle of poverty in the world [16].

Added to this highly worrying panorama regarding toxocariasis, Toxocara spp. is considered, by the year 2050, the greatest global threat of zoonotic soil-transmitted helminthiases [17]; furthermore, one of the five most important neglected diseases in the world [18]. Due to the little investment in research in the most affected countries, economic resources must be allocated to fill the great gap in the effective control of this parasite in dog and cat populations: effective vaccines [19]. Especially in pregnant bitches, which are capable of transmitting L3 to their offspring via transplacental or lacteal (vertical transmission), a situation that perpetuates environmental contamination with eggs of this parasite and the risk of infection in communities [20].

The aim of this book chapter is to provide complementary information to the existing classic information regarding the understanding of the importance of toxocariasis in public health and possible comprehensive control mechanisms of this parasite within urban communities.

2. Toxocara and its perpetuity in urban communities

It is estimated that in the future toxocariasis will be considered the main zoonosis associated with soil-transmitted helminths, as well as the most neglected emerging parasitic zoonotic disease in the world [17, 21]. According to the World Health Organization (WHO) in its book entitled “Ending the Neglect to Achieve the Sustainable Development Goals a roadmap for neglected tropical diseases 2021-2030” [18], one of its main objectives is to control helminthiases transmitted by soil. Especially toxocariasis, given its important impact on public health, especially among poor people in many countries around the world.

Today, even though there are indicators of approximately 1.4 billion people exposed or infected by Toxocara spp., toxocariasis remains an underdiagnosed parasitic disease [22], with underestimated epidemiological rates, as well as the real impact of this pathology on global public health [12, 14, 23]. Because the diagnosis of this parasitic infection in humans is subject to serological examination that detects antibodies against Toxocara excretory-secretory (TES) antigens. This test, however, has low specificity (cross-reactions with other helminths) and is not capable of discriminating the asymptomatic form from those that lead to other syndromes, or historical chronic or acute infections [24, 25].

Added to these epidemiological conditions, the life cycle and transmission processes of Toxocara spp. between its different hosts is highly complex and has multiple variables immersed in its understanding (Figure 1). Although there are highly defined and understood variables: 1. The presence of dogs and cats, especially puppies, is significantly associated with the risk of exposure to L3 or embryonated eggs of Toxocara spp. to its different hosts, among them humans [26]. 2. The vertical transmission of T. canis allows early superinfection in puppies, which are a fundamental pillar in the dissemination of eggs in the environment [20]. 3. The eggs of Toxocara spp. are resistant to different environmental conditions, managing to reach their hosts through various means of contamination, including water [27]. 4. The presence of the parasite is cosmopolitan, with its transmission/infection processes estimated in more than 100 countries [28], being highly related to disabling diseases that reduce the productivity of a community by up to 35% [29].

Figure 1.

Complexity of the biological cycle of Toxocara. A and B. In the intestine of dogs and cats (definitive hosts), the sexually mature forms of Toxocara are present; their unembryonated eggs come out through the feces. Under favorable environmental conditions (temperature between 25 and 30°C and relative humidity 85–95%), in 9–15 days, there is complete embryogenesis, achieving the infectious larval stage (L3). These embryonated eggs enter their definitive hosts through the oral route, hatch in the intestine, and begin migration. In puppies and kittens under 3 months of age, after migrating through the liver, kidneys, lungs, and trachea, they return to the intestinal lumen to differentiate sexually and lay eggs (prepatent period 4–5 weeks). In puppies and kittens older than 3 months, L3 migrates and encysts in various tissues, training in a state of quiescence/hypobiosis. C. Hormones associated with pregnancy in dogs, such as prolactin and progesterone, generate “awakening” from the quiescent state of L3, establishing vertical transmission (transplacental and transmammary). In queens, if Toxocara cati infection occurs during lactation, there is a probability of establishing transmammary transmission to the kittens. C1. Through the L3-contaminated emetic content of super-infected puppies or kittens, the bitches or queens can become infected. D. Wild or synanthropic (feral) canine or feline species can also spread eggs in the environment. E. Although there is no certainty about the participation of definitive atypical hosts for T. canis or T. cati (e.g., adult forms of T. canis have been found in the intestine of cats), these should be in the epidemiological research processes of this parasite. F and F1. Toxocara is considered a parasite associated with food- and waterborne diseases, especially in the consumption of paratenic hosts (e.g., poultry) without adequate cooking. G. Small mammals are suspected of contributing to the spread of Toxocara and aiding the survival of the parasite during periods when there is a temporary absence of suitable definitive hosts; if a cat preys on a paratenic host (e.g., parasitized mouse), the prepatent period could be shortened to 3 weeks. G1 and H1. Flies can be passive vectors of Toxocara. H and I. In humans, there are various routes of oral contamination with Toxocara eggs, from consumption of paratenic hosts to exposure to geophagy. After L3 infection in humans, several larva migrans syndromes can develop. J. Cats and dogs through their coat can also carry embryonated eggs or L3 of Toxocara, probably acquired in common public areas.

Due to the magnitude of contamination of public places with dog and cat feces, these family recreation places become important sources of exposure to infection by Toxocara spp. [30]. Fakhri et al. [31] published that the global prevalence of Toxocara eggs in public places was 21% (95%CI, 16–27%). They also estimated 13–35% of prevalence rates in different WHO regions, where a high prevalence was significantly associated with high geographical longitude, low latitude, and high relative environmental humidity. Thus, the highest prevalence was in the Western Pacific (35%; 95%CI, 15–58%) and the lowest in North and Central America (13%; 95%CI, 8–23%).

On the other hand, Rostami et al. [32] have recently published that the global Toxocara spp. seroprevalence rate in people was 19% (95%CI, 16.6–21.4%). A significantly higher seroprevalence was associated with a lower income level, human development index, and latitude but higher humidity, temperature, and precipitation. According to seroprevalence by WHO regions, the highest was 37.7% in the African region (95%CI, 25.7–50.6%) and lowest in the 8.2% in the Eastern Mediterranean region (95%CI, 5.1–12.0%).

This same type of study, regarding estimated global prevalences for Toxocara, has been carried out for dogs and cats. In dogs, it was 11.1% (95%CI, 10.6–11.7%), where a highly significant prevalence was associated with puppies (≤12 months of age), stray and rural animals, and bitches. As for the prevalence by WHO regions, Eastern Mediterranean (95%CI, 13.7–25.5%) has the highest with 19.2%, and the lowest was 6.4% for Western Pacific (95%CI, 3.3–10.2%) [33]. China draws attention, given that in that country, dogs are consumed as a source of animal protein in the diet of communities, so it is the only epidemiological indicator of direct presence of adult stages of Toxocara spp. in 45.2% of dogs that were slaughtered for consumption [34].

In the case of cats, the estimated Toxocara infection in the world was 17.0% (16.1–17.8%). The highest was associated with low-income tropical countries and stray with 28.6% (95%CI, 25.1–32.1%) and kittens (≤12 months of age) with 27.7% (95%CI, 23.4–32.0%). In turn, being the infection by Toxocara spp. in cats, highest in African countries 43.3% (95% CI, 28.3–58.4%) and lowest in South American countries 12.6% (95% CI, 8.2–17,0%) [35]. Figure 2 shows the prevalence of patent Toxocara spp. infection (eggs in feces, coprodiagnosis) in dogs and cats in several countries around the world, allowing us to understand the cosmopolitan capacity of the parasite.

Figure 2.

Several prevalence of coprodiagnosis of Toxocara spp. infection in dogs and cats in some countries of the world.

The perpetuity of Toxocara spp. in urban communities, even in developed countries [36], is strengthened, due to the apparent broad geographic distribution of Toxocara and multiple transmission routes indicating that toxocariasis is a common helminth infection in humans [21]. Likewise, based on the epidemiological principle that T. canis infection has a high prevalence in the entire dog population that is not treated with anthelmintics on a regular basis, and also, its infection capacity in synanthropic and wild species, which escape of the usual anthelmintic controls, makes its elimination almost impossible [37]. Additionally, Toxocara has characteristics of extreme hypobiosis in its paratenic hosts. Viable larvae have been found even after 9 years of residence in non-human primate tissues [38]. This information can be extrapolated to the role that small mammals play in maintaining L3 in hypobiosis in their tissues, which when preyed on by dogs or cats would help maintain the parasite cycle within urban communities [39]. For these reasons, cats are underestimated in their role in human toxocariasis, even though their offspring can become infected transmammarily, thus allowing superinfected kittens [40].

Likewise, this situation is aggravated through the cycle of uncontrolled populations of dogs and cats, especially stray animals, as well as dogs and cats from low-income families that do not have the economic requirements to access quality commercial dewormers [41]. This situation, in the case of dogs, is serious, due to the 100% risk of being born with T. canis infections. These puppies, which are anthropogenic beings (they arouse people’s affection), access different areas of the home and public areas, managing to excrete thousands of Toxocara unembryonated eggs. Eggs are resistant to various environmental conditions, where they embryon and become infective [42], thus providing favorable environments to infect various hosts, among which are people. To “close” (strengthen) this cycle of perpetuity, toxocariasis is a neglected disease, a situation where governments do not specifically invest in its study and control [21, 43].

3. Approach to comprehensive control of Toxocara

The definition of comprehensive control refers to the holistic management of a situation, in this case knowing the multiple variables implicit in the presence and risk of infection by Toxocara spp. in urban communities and building a path of action possibilities (Figure 3). Without a doubt, dogs and cats play a predominant role in being the definitive hosts of Toxocara spp. [37]. Still, understanding that toxocariasis is a neglected disease and of a non-reportable nature for the world’s health systems is vital [44]. For this reason, the role played by raising awareness among all members of the community regarding the health problems associated with toxocariasis should be the initial step in the integrated control work [45].

Figure 3.

Possible variables to develop in the constitution of an integrated control of Toxocara in urban communities.

The education of communities, from their state, governmental, and social leaders to family core, must be sensitized. Topics on zoonotic soil-transmitted helminthiasis, responsible ownership of dogs and cats, collection of feces and its correct disposal, selective strategic deworming for Toxocara in dogs and cats according to their age. Also, other topics such as personal hygiene habits and good food-handling habits, among many other topics, are necessary to build knowledge, risk perception, and mitigation measures for toxocariasis in children, people with altered immune response, and nursing homes, among others [46].

The approaches of all levels of education in society are important to understand the silent scourge of toxocariasis. The use of Web-based educational resources, NEMBASE http://www.nematodes.org/nembase4, Nematode.nethttp://nematode.net, WormBase ParaSite http://parasite.wormbase.org/, Centers for Disease Control and Prevention (CDC, http://www.cdc.gov), and the American Association of Veterinary Parasitologists (AAVP, http://www.aavp.org/)could help in this activity. Likewise, the economic investment of States in macro research projects that allow precise epidemiological data by ecosystem regions in different countries and their communities, as well as technological developments for the control of Toxocara in dogs and cats (e.g. vaccines) [7, 47, 48, 49].

Within this process of educating community members, the responsible management of antiparasitic drugs is a fundamental pillar. The current guidelines of associations, the European Scientific Counsel of Companion Animal Parasites (ESCCAP; www.esccap.org), the Tropical Council for Companion Animal Parasites (TroCCAP; www.troccap.com), and the Companion Animal Parasite Council (CAPC; www.capcvet.org), recommend serial anthelmintic treatment. Every 15 days, from 2 weeks of age, puppies and kitties (under 12 weeks of age), using nematocidal antiparasitics specific to each animal species. For dogs and cats older than 12 weeks of age, selective strategic deworming should be performed every 2 to 3 months, depending on whether or not they are exposed to environments at risk of infection (e.g., visiting new parks contaminated with Toxocara eggs).

These deworming times are subject to: 1. Transplacentally parasitized puppies from 14 days of age begin to eliminate eggs through their feces. 2. Under most conditions, the prepatent period of Toxocara spp. is defined between 33 and 58 days; this being understood as the time elapsed between exposures to L3 by the host, until the moment of reaching the possibility of oviposition by the adult female [50].

Although it is not common to find effective disinfectants in the control of Toxocara eggs spread throughout the environment [51], in homes where there are puppies or/and kittens, there must be hygiene protocols for common family areas to which these animals have access. Recently, Zhang et al. [52] have published that the chlorocresol-based disinfectant product “Neopredisan®135–1” against to embryogenesis and viability of T. canis eggs. Such killing activity increases in a concentration- and time-dependent manner, with a maximum killing efficacy of 95.81% at 4% concentration and 120 min exposure time.

In turn, urban communities must group together and use antiparasitic baits for stray dogs and cats that cohabit public recreation spaces. There are examples of control of other gastrointestinal parasites in dogs and cats with this action [53, 54, 55]. This initial activity is vital to stop high loads of embryonated eggs in the environment of the urban community, in addition to reducing risks of contamination of spaces within homes where puppies and kittens are present. Nowadays, the use of parasiticide fungi, such as Mucor circinelloides (ovicide) and Duddingtonia flagrans (larvicide), has an important role in the ability to reduce the environmental load of gasrointestinal parasites, even in places with a high density of dogs and cats [56].

The biggest problem to control within the life cycle of Toxocara (Figure 1) refers to avoiding vertical transmission of the parasite, especially in bitches, which can transmit L3 to their offspring in utero and through the milk. On the other hand, the cats only transmit L3 to their offspring through milk when they suffer from Toxocara cati infection while they are lactating [57]. This is where homes that let their cats outside or stray can be exposed. The bitches’ deworming schemes must be very precise regarding their gestation times. A macrocyclic lactone, Moxidectin, should be used on days 40 and 55 of gestation [58]. Deworming scheme based on the activation of L3 in tissues of pregnant bitches, these L3 come out of the hypostatic state at 42 days of gestation by prolactin peaks [59].

Being clear regarding the existing antiparasitic drugs protocols for the control of Toxocara spp. in dogs and cats, which must be socialized with responsible owners of cats and dogs [60]. The step to follow in integrated control is active epidemiological surveillance. Serial coproparasitological tests in dogs and cats are indicated to evaluate the effectiveness of antiparasitic agents and their frequency of use. The Kato-Katz technique is particularly easy to standardize in veterinary clinics or laboratories, in addition to being highly sensitive for Toxocara [61]. Monitoring the effectiveness of deworming through preventive coproparasitology carried out two to four times a year for puppies or kittens (<1 year old) and once or twice per year for dogs and cats (older than 1 year). Likewise, the measurement of soil contamination in common public areas (e.g., parks).

In the same way, indirect ELISA techniques use TES antigens to screen human, dog, and cat populations. Given that ELISA can generate cross-reactions with other helmint gastrointestinal infections, the results obtained from possible positives must be confirmed with the Wester blotting technique. This will provide specific epidemiological data on mitigation measures within the communities [62].

Without a doubt, the staging of a vaccine for the prevention and control of Toxocara spp. will be the fundamental pillar of a complete comprehensive plan for toxocariasis [19, 63]. Vaccines are a product that stimulates the immune system to produce immunity against a specific disease, protecting the host of that disease from the infecting agent, whether bacteria, viruses, or parasites, including neoplastic cells [64]. Vaccines can stimulate the production of antibodies and cellular immunity; and in many cases, it is strictly necessary to enhance their immunogenic effect using adjuvants [65].

Reverse vaccinology allows the development of effective vaccines based on the genomic information of the infectious agent [66, 67]. In the world, there are important examples of control of gastrointestinal parasites in domestic animals through vaccination [68]. In the case of T. canis, the crucial point for the development of studies associated with vaccinology was the T. canis genome project, where Zhu et al. [69] reported that the genome of this parasite has a size of 317 Mb and encodes at least 18,596 genes that express proteins.

Based on this information, recent studies led by Zhou et al. [70] have explored details of the molecular biological processes in this parasite. They obtained high-throughput transcriptomic sequences of male and female T. canis of its 18,596 genes, performing a detailed bioinformatic analysis. Metabolomics studies were also carried out, where the nonprotein components of the parasite extract were characterized for the three metabolic pathways: fatty acid, amino acid, and carbohydrate metabolism [71]. Soleymani et al. [72] through proteomic analyses identified a variety of proteins from the soluble extract of T. cati adults, which could have a role in the host–parasite interaction, as well as 10 somatic proteins of this parasite with the capacity to generate an immune response by the host.

These studies allowed us to establish plausible bases for the identification of proteins of immunological interest for the generation of vaccines using the reverse vaccinology methodology. Recombinant proteins like potassium channel homologous protein (rTcVcam) and cadherin homologous protein (rTcCad), demonstrated immunogenicity in the murine model of toxocariasis and conferred a reduction in larval migration [73]. These proteins were selected because they were part of the cell membranes of the parasite; in theory, they behaved as hidden antigens and probably mediated the immune response to the parasite by the host [74, 75, 76].

Within reverse vaccinology, in-silico analyzes are important to determine the recombinant protein to be expressed. In the case of the first clinical trial in dogs [77], programs such as BLASTX (http://blast.ncbi.nlm.nih.gov/Blast.cgi) to identify possible homologous sequences, PSORT (http://www.psort.org/) to identify the cell location, TMHMM (http://www.cbs.dtu.dk/services/TMHMM-2.0/) and SOSUI (http://bp.nuap.nagoya-u.ac.jp/sosui/) to identify signal peptides and transmembrane helices, and ScanPROSITE (http://au.expasy.org/prosite/) to identify conserved domains and regions in the sequences were used.

Jaramillo-Hernández et al. [77] tested these recombinant proteins in puppies with various adjuvants, finding that rTcVcan + QuialA® promoted reduction in the parasite eggs in feces (95%) and eggs reduction obtained from the uteri of pharmacologically expelled adult females (58.38%).

In the near future, hopefully immediate, efforts should be made to research more promising antigens for the development of effective and efficient vaccines to control the vertical transmission of T. canis and T. cati. It is imperative to expand the possibility of integrated control of this zoonotic geohelminth, due to its devastating impact on the development of stable urban communities. In addition to exploring other parasite–host interactions, where the proteome composition of TES antigens has been identified, and according to the findings of computer-based analyses at the (http://crdd.osdd.net/raghava/cancerppd/index.php) site, part of the T. canis-secreted protein with the 18 amino acids showed a high degree of similarity (≈93%) to other anticancer agents [78].

4. Conclusion (author’s opinion regarding Toxocara and the cycle of poverty in low-income countries, such as Colombia)

José Saramago and his masterpiece “Blindness” supports the power of observation, of those who can do it, the high social responsibility and preservation of the species, when others have lost that option (or have never had it). This is the case of some of the gastrointestinal parasites that can be transmitted to humans by domestic, wild, or synanthropic animals (e.g., pigeons), parasitic diseases called zoonotic geohelminthiases.

Now, the use of the Greek prefix “geo” to name these diseases refers to the high capacity of these parasites to persist and be transmitted through the soil, for example, through the green area of a park. Now, if we combine the aforementioned considerations, we can have the following picture of perfect epidemiological transmission: first, the ownership of dogs and cats—without adequate internal deworming protocols (especially in populations with limited economic resources); second, the cultural incompetence to pick up the excrement of these pets in public areas; and third, the dispersal of millions of eggs of gastrointestinal parasites, through the excrement of these dogs and cats, in the environment where humans live. Conditions that increase the probability of accidental infection, mainly in children, of these helminths (establishing parasitic zoonosis).

From the classic clinical medical perspective, this would not seem important; the learned doctors will say, “if you have a parasite, you deworm yourself and that’s it.” But it turns out that many of these zoonotic geohelminths take humans as a “paratenic host;” that is, they infect them but do not complete the development of their entire biological cycle and end up encysted, thus leaving them outside the therapeutic effects of the classic antiparasitic agents used in medicine, considering also that they have migrated through various tissues (e.g., central nervous system) where they cause syndromes that are very difficult to diagnose.

This parasite–human interaction triggers multiple alterations, most of them subclinical (imperceptible to conventional medical examination). Of the most important alterations in the lives of people exposed at a young age to these infections, the erratic responses to vaccines stand out (e.g., alteration in the expected response to vaccination against cholera in children). Intensify the so-called “cycle of poverty”, where infants and children have serious cognitive disabilities for an adequate learning process, which eventually leads them to abandon their school studies or to the impossibility of starting and/or completing their university studies. Helminthiases are the etiology for thousands of deaths and DALY (disability-adjusted life year) annually and are responsible for a 6–35.3% loss in productivity.

As I expressed previously, the majority of low-income families own pets and do not have the opportunity to deworm them adequately (most quality systemic dewormers are expensive). Therefore, it is highly likely that in these conditions, the infants will become infected and are constantly exposed to these zoonotic geohelminths, who end up being their paratenic hosts and who silently develop serious cognitive alterations that prevent them from accessing, maintaining, and graduating from higher education studies. In conclusion, without academic training that guarantees improving their economic income, it is highly likely that they will exacerbate/perpetuate their states of poverty.

This type of epidemiological-medical situations is widely unknown by the majority of the world’s health systems, especially the Colombian one, where there are hardly any lines of work in public health associated with the control of the main zoonotic geohelminthiasis: toxocariasis (gastrointestinal parasite that yes or if it is transmitted to canine puppies through the placenta or milk secretion of their mothers, where approximately 14 days after birth a puppy can expel 1,000,000 eggs into the environment through its feces). This situation of hopelessness—lack of interest in working on the knowledge, status, and control of this type of diseases that afflict multiple people—determines that they are called “neglected diseases.” Where not only the historical indifference of the government condemns the endemic situation (permanent in the environment), and uncontrolled of it, but also the resources and research groups that are added to the task of studying them, we are counted on the fingers that write this book chapter.

Finally, if we see the tip of the iceberg, and we are afraid of colliding with it; imagine the magnitude of the body of this phenomenon. If we make an analogy, the tip of the iceberg would be the classic diseases that must be registered in the country’s precarious health system (e.g. Dengue, HIV, and COVID-19, among others), and the body would be all those that go unnoticed and ignored. As in the “Blindness,” public health researchers, biologists, parasitologists, internal medicine doctors—infectious disease specialists, immunologists, veterinary doctors, and epidemiologists, among others—are called to recommend, direct, and demand from the government to generate the optimal environment to think and execute strategies that mitigate this painful public health situation, given that we are the ones who can observe this situation. If and only then, this health disaster in Colombia and others low-income countries could turn into a true change that allows everyone to have opportunities for growth in their quality of life in a fair and equitable manner.

Acknowledgments

To “Jaboneros,” my lovely family.

Conflict of interest

The author declares no conflict of interest.

Appendices and nomenclature

AAVP	American Association of Veterinary Parasitologists
CDC	Centers for Disease Control and Prevention
CT	covert/common toxocariasis
DALY	disability-adjusted life year
ELISA	enzyme-linked immunosorbent assay
L3	third-stage larvae of Toxocara spp.
TES	Toxocara excretory-secretory