Arxiu d'etiquetes: parasites

DNA: the solution to combat the dog mess

You are walking quietly and suddenly you smell an unpleasant odour. You look from side to side and you see nothing, but the smell continues there. Then, you lift your foot and, effectively, you have stepped a dog poop. You cannot deny it because everybody has happened it. However, DNA can finish with the lack of public spirit. If you do not believe it, I suggest you to continue reading.


To have a dog is not only feed up it and play with it, but its owners are the person responsible to duck and clean the dog mess and deworming it. However, few people do it.

In the street, in playgrounds or in front of the home’s door you can find the dropping of a dog because its owner has not cleaned it. Although there are many campaigns against the lack of public spirit of some dog owners and there are also economic sanctions, today is an unresolved issue.

To leave dog droppings is not only an unsightly problem, but it goes beyond because parasitized stools are a public health issue. If the stools are not cleaned soon, eggs or cysts presents in them may become infectious forms and represent a risk to people or children who play in the playground. The rain dissipates the stools and people do not see them, but the parasites are still there.

Intestinal worms cause diseases to dogs and cats and people, especially in children and immunocompromised (HIV, transplant patients or with some types of cancer subjected to long immunocompromised therapies).

Parasites can cause health affect to stomach and intestines, but the worst is in the eyes. The parasite Toxacara canis can cause the total loss of vision of the eye that infects.


Oscar Ramírez is the person responsible of the Can-ID project (Figure 1), developed by the Catalan company Vetgenomics SL to combat stools in public spaces. This is a system of canine identification by DNA, based on a chip of 128 markers (SNPs).

Figure 1. Logo of Can-ID (Source: Vetgenomics SL)

The aim of Can-ID is identify all dogs of a municipality with a chip to get a census of dogs. When a council’s technician finds a dog mess, he will pick up a sample and he will send it to analyse. Then, if the DNA removed of the sample coincides with the chip of some registered dog, it will know who the dog owner is. Finally, the council could fine this person.

This project is based on two phases:

Phase 1: genetic identification of all dogs of municipality

  • Involvement of vets in the collection of blood or saliva samples
  • Identification plate with QR code, which the owner can activate in case of loss of the dog
  • Transport with custody system of samples
  • Analysis of the samples and obtaining the genetic profiles
  • Creation, management and conservation of the database with the genetic profiles of dogs in the municipality

Phase 2: identification of owners with a lack of public spirit

  • Non civic owner does not pick up his dog’s stool from the street
  • Collection of samples in the presence of members of the local police
  • Transport with custody system of samples
  • Analysis of stool samples in a laboratory specialized in non-invasive samples
  • Comparison of the genetic profile of the stool with the database. Identification of the dog

In order to realize the first phase, the municipality has to modify the municipal ordinances so that, in addition to force the registration of the dogs and an identification by a chip, their owners also submit them to a blood test that will help to make a database.

Unlike what many people think, genetic identification has not a great cost. Moreover, the cost of cleaning the municipality is higher. The first phase has a cost of 35€ per sample and includes the extraction of a sample by a vet and its custody for analysis. The second phase is also around 30€ and the amount of the fine is around 300-600€, depending the city. Therefore, the municipalities that implement this system would recover the investment.

Parets del Vallès (Barcelona) is the first town to implement this system. In the first 3 months, the municipality pays for the collection of samples and their custody, through an awareness campaign.


This system has a greater number of markers respect to other identification systems (Table 1), but it also has internal pollution controls.

This system allows to exclude the false positives. A dog may urinate on a stool in the street. This would contaminate the sample, but this system is able to identify if the sample contains more than one DNA. If so, the sample would be excluded.

It can also happen that the dog is not registered or is from another population. But you can obtain a robot portrait and put stronger pressure on dog owners who comply the characteristics of the robot portrait (example: hair colour).

table 1 eng.jpg
Table 1. Comparision of the Can-ID system respect others identification systems (Source: Oscar Ramírez, Comparative Genomics programme from Master’s Degree in Cytogenetics and Reproductive Biology in UAB)

In addition to identify these people, Can-ID can be applied for genetic identification and paternity tests or monitoring of wild-wolf populations from non-invasive samples too (stools, hair, urine).

We hope that more municipalities will join this initiative and reduce the lack of public spirit of some people, which may affect public health.



Symbiosis: relationships between living beings

Predation, parasitism, competition… all living beings, besides interacting with the environment, we relate to other living beings. What types of relationships in addition to those you know? Do you feel like to know them?


The group of all living beings in an ecosystem is called biocenosis or community. The biocenosis is formed in turn by different populations, which would be the set of individuals of the same species occupying an area. For survival, it is imperative that relations between them are established, sometimes beneficial and sometimes harmful.


They are those that occur between individuals of different species. This interaction it is called symbiosis. Symbiotic relationships can be beneficial to a species, both, or harmful to one of the two.

Detrimental to all the species involved:

Competition: occurs when one or more resources are limiting (food, land, light, soil …). This relationship is very important in evolution, as it allows natural selection acts by promoting the survival and reproduction of the most successful species according to their physiology, behavior …

Las selvas son un claro ejemplo de competencia de los vegetales en busca de la luz. Selva de Kuranda, Australia. Foto de Mireia Querol
Rainforests are a clear example of competition between vegetals in the search for light. Kuranda rainforest, Australia. Photo by Mireia Querol
One species has benefits and the other is detrimented:
  • Predation: occurs when one species (predator) feeds on another (prey). This is the case of cats, wolves, sharks
foca, león marino,
Great white shark (Carcharodon carcharias) jumping to depretade a marine mamal, maybe a sea lion. Photo taken from HQ images.
  • Parasitism: one species (parasite) lives at the expense of other (host) and causes it injury. Fleas, ticks, pathogenic bacteria are the best known, but there are also vertebrate parasites, like the cuckoo that lay their eggs in the nests of other birds, which will raise their chicks (brood parasitism). Especially interesting are the “zombie parasites”, which modify the behavior of the host. Read this post to learn more!
    Carricero (Acrocephalus scirpaceus) alimentando una cría de cuco (Cuculus canorus). Foto de Harald Olsen
    Reed warbler (Acrocephalus scirpaceus) feeding a cuckoo’s chick (Cuculus canorus). Photo by Harald Olsen

    Parasites that live inside the host’s body are called endoparasites (such as tapeworms), and those who live outside ectoparasites (lice). Parasitism is considered a special type of predation, where predator is smaller than prey, although in most cases does not cause the death of the host. When a parasite causes illness or death of the host, it is called pathogen.

    Cymothoa exigua es un parásito que acaba sustituyendo la lengua de los peces por su propio cuerpo. Foto de Marcello Di Francesco.
    Cymothoa exigua is a parasite that replaces the tongue of fish with their own body. Picture by Marcello Di Francesco.

Kleptoparasitism is stealing food that other species has caught, harvested or prepared. This is the case of some raptors, whose name literally means “thief.” See in this video a case of kleptoparasitism on an owl:

Kleptoparasitism can also occur between individuals of the same species.

One species has benefits and the other is not affected:
  • Commensalism: one species (commensal) uses the remains of food from another species, which does not benefit or harm. This is the case of bearded vultures. It is also commensalism the use as transportation from one species over another (phoresy), as barnacles attached to the body of whales. The inquilinism is a type of commensalism in which a species lives in or on another. This would apply to the woodpeckers and squirrels that nest in trees or barnacles living above mussels. Finally, metabiosis is the use of the remains of a species for protection (like hermit crabs) or to use them as tools.
    El pinzón carpintero (Camarhynchus pallidus) utiliza espinas de cactus o pequeñas ramas para extraer invertebrados de los árboles. Foto de
    The woodpecker finch (Camarhynchus pallidus) uses cactus spines or small branches to remove invertebrates from the trees. Picture by Dusan Brinkhuizen.
    Both species have benefits:
  • Mutualism: the two species cooperate or are benefited. This is the case of pollinating insects, which get nectar from the flower and the plant is pollinated. Clownfish and anemones would be another typical example, where clown fish gets protection and food scraps while keeps predators away and clean parasites of the sea anemonae. Mutualism can be optional (a species do not need each other to survive) or forced (the species can not live separately). This is the case of mycorrhizae, an association of fungi and roots of certain plants, lichens (mutualism of fungus and algae), leafcutter ants

    Las hormigas Atta y Acromyrmex (hormigas cortadoras de hogas) establecen mutualismo con un hongo (Leucocoprinus gongylophorus), en las que recolectan hojas para proporcionarle nutrientes, y ellas se alimentan de él. Se trata de un mutualismo obligado. Foto tomada de Ants kalytta.
    Atta and Acromyrmex ants (leafcutter ants) establish mutualism with a fungus (Leucocoprinus gongylophorus), in which they gather leaves to provide nutrients to the fungus, and they feed on it. It is an obligate mutualism. Photo taken from Ants kalytta.


They are those that occur between individuals of the same species. They are most beneficial or collaborative:

  • Familiars: grouped individuals have some sort of relationship. Some examples of species we have discussed in the blog are elephants, some primates, many birds, cetaceans In such relationships there are different types of families.
  • Gregariousness: groups are usually of many unrelated individuals over a permanent period or seasonal time. The most typical examples would be the flocks of migratory birds, migration of the monarch butterfly, herds of large herbivores like wildebeest, shoal of fish

    El gregarismo de estas cebras, junto con su pelaje, les permite confundir a los depredadores. Foto tomada de Telegraph
    Gregariousness of these zebras, along with their fur, allow them to confuse predators. Photo taken from Telegraph
  • Colonies: groups of individuals that have been reproduced asexually and share common structures. The best known case is coral, which is sometimes referred to as the world’s largest living being (Australian Great Barrier Reef), but is actually a colony of polyps (and its calcareous skeletons), not single individual.
  • Society: they are individuals who live together in an organized and hierarchical manner, where there is a division of tasks and they are usually physically different from each other according to their function in society. Typical examples are social insects such as ants, bees, termites

Intraspecific relations of competition are:

  • Territorialityconfrontation or competition for access to the territory, light, females, food can cause direct clashes, as in the case of deer, and/or develop other strategies, such as marking odor (cats, bears), vocalization

    Tigres peleando por el territorio. Captura de vídeo de John Varty
    Tiger figthing for territory. Video caption by John Varty
  • Cannibalism: predation of one individual over another of the same species.

And you, as a human, have you ever thought how do you relate with individuals of your species and other species?