Wednesday, March 30, 2011

The Emperor and its Dancer


Hexabranchus sanguineus, more commonly known as the Spanish dancer, is a carnivorous slug found mostly in the waters surrounding Hawaii. It is called a Spanish dancer because of how its bright colors and movement through the water resembles a Flamenco dancer [1]. Some species of the slug are toxic, obtaining their toxicity by ingesting other toxic organisms, like the Portuguese man-of-war and many are most active at night [2]. In the daytime, they are pink with white patches, and at night, they are pinkish red and blotchy. Its mutualistic partner, Periclimenes imperator, is an emperor shrimp found in all areas of the Pacific Ocean, from Hawaii to Indonesia [4]. These organisms look like mini-lobsters with a duck-bill like head [5]. They also have the pink-red with white spots coloration, similar to that of the Spanish dancer and other organisms it inhabits.

Description of Relationship

The relationship between Hexabranchus sanguineus and Periclimenes imperator has long been established as mutualistic [1]. Although both can survive without the other, there are advantages to a shared interaction. The relationship is established simply through encounter. If these organisms meet, and both do not mind creating a relationship with the other, then interaction is formed. The shrimp can be found within the gills of the slug [2] and cleaning off any kind of growth and even parasites. Usually the shrimp is not alone, cleaning and travelling with a partner. The slugs receive a thorough cleaning while the shrimp receive a great food supply. A unique characteristic of this relationship is that once it is established, it usually remains for the life of the organisms [3].

Cost/Benefit Analysis

The benefits have been discussed above; however, there are some possible risks to each organism as well. Sometimes, when predators of the shrimp try to attack, the slug gets damaged or killed in the process. This emphasizes the importance of the shrimp’s ability to blend in with the slug [5]. Also, because the slug has to carry around the shrimp, extra energy has to be expended. The costs for the shrimp are minimal as well. There could be a chance that the slug accidentally eats the shrimp or if the shrimp accidentally ingests part of a toxic slug. This, however, probably does not occur frequently since the shrimp stay by the gills of the slug.


Tuesday, March 29, 2011

Remora: Not Quite a Drag


Remora are a group of fish that are members of the family Echineidae; there are eight known species, all belonging to one of four genera: Echineis, Phtheirichthys, Remora, and Remorina [4]. They are usually found in warm, southerly waters. Remora interact with a wide range of marine animals. They are known to attach themselves to fish (particularly sharks and rays) and whales, along with other large marine animals – and even the occasional snorkeler or scuba diver [2]. Remora possess a modified dorsal fin that runs from just above the snout of the fish to the nape of its neck. This fin has several transverse plates; it is used by the remora to attach itself to its host. Some remora cling to the host’s torso, but others are found on or near the host’s gills. The name “remora” is the Latin word for “delay”; they were believed to slow down ships and animals that they clung to because of the weight they add and the drag they produce.

Description of the Relationship:

Unfortunately, very little is known about the origin of remora and the evolution of their unique trait and behavior. While other fish – such as the “cleaner fish” studied earlier in the semester – exist in a relationship that superficially resembles the one between a remora and its host, no other identical examples are known.

Depending on the type of remora and the host, the relationship can be either mutualistic or commensal. Most often the relationship is commensal – the remora attach themselves to a host and travel on it, gaining transport, protection from predators, and food. This relationship is commensal when the remora eats scraps left behind by the host or other debris it is exposed to in the host’s travels, but can become mutualistic if the remora is of a variety that eats dead skin and bacteria from the host’s body [1]. In either case the remora benefits from the relationship, while the host either is unharmed or actively benefits along with the remora; for this reason it is impossible to definitively categorize the remora/host relationship as either mutualistic or commensal.

Cost/Benefit Analysis:

Whether the relationship is commensal or mutualistic, in nature there is little or no harm to the host. In commensal cases, it has an unexpected passenger that does not seek to harm it and that will, at worst, either slow it down by increasing drag on the host as it swims or perhaps cause some minor gill irritation. In mutualistic cases, the host benefits as the remora cleans its host of dead skin, bacteria, and ectoparasites.

Similarly, the remora always benefits from this relationship in a natural environment. Whether the relationship is commensal or mutualistic it gains food, shelter, and protection. Since the remora can detach itself from its host, and is capable of swimming freely, its well-being is not linked to that of the host [2]. Some scientists hypothesize that remora run the risk of being eaten by their hosts, but to date no evidence has been found supporting this idea.

This relationship has incurred some harm for both the remora and their hosts in cases where they live in a human-populated environment due to an unusual fishing practice of some aboriginal tribes. In some regions where remora are prevalent, fisherman use a live remora tied with a long cord in lieu of a fishing hook and rod – they wait until a game fish is spotted, release the remora, allow it to attach itself to the game fish, and then haul both back in with the rope. In some regions the un fortunate remora is eaten along with the game fish, but in other areas they are honored for their contribution to the tribe’s well-being [2]. Despite the man-made disadvantage, the relationship persists because it provides remora with ready food and the high-speed motion they need to keep their gills functioning [2].

Remora in Action:






Friday, March 25, 2011

Cordyceps: mind and body controller


The relationship between Cordyceps and its hosts is strictly parasitic since the Cordyceps end up killing their host. The host ranges from ants to moths to walking sticks. Cordyceps are endoparasitoids meaning they attack inside their hosts; ending up taking over the host brain and body[1]. This fungus spreads its seeds just like any other plant; however once the pollen infects its host is when it acts differently. The cordyceps, still unknown, but somehow travels through the host body until reaching the brain where it infects and takes over them. Infected ants are known to outcast infected ants and even taken as far away from the colony once known infected. The reason for this is the outcome of these infected hosts. They disorientate their host and forces them to attach to nearby limbs. There the fungus does its work by sprouting the fungus sprout out of the head where they later end with a cluster of capsules. When finished, the capsules burst to release more spores into the air to try to infect other host passing by.


The hosts of the Cordyceps ranges from different arthropods such as the Odonata, Blattaria, Hemiptera, Coleopter, Phasmida, Hymenoptera, and Lepidoptera, each depending on the species of the Cordyceps [2]. Even though the Cordyceps affects so many different insects, they are not considered harmful; they are more of nature’s pesticide for insects which get too numerous


Recently Cordyceps are used in Chinese medicine to help fatigue resistance, improve stress tolerance, enhance immune function and improve general health[3]. The specific species the Chinese use is the cordyceps sinensis species which is also known as the Chinese caterpillar.

The Cordyceps are very similar to species we learned in class such as the Dicrocoelium which infects the ant host into controlling the mind. They then force the ant to crawl up stalks and intentionally get eaten by the next host, live stalk. However instead of forcing the ant to crawl and get eaten, Cordyceps kill the ant and release spores from the body of the host.







Monday, March 21, 2011

Nemo Really Does The Finding

[6] Introduction

Sea anemones and clownfish engage in a mutualistic relationship that offers protection and increase in food availability to both.
Sea anemones have tentacles that usually sting and repel other fish, excluding clownfish, which are shielded by protective mucus that covers their bodies. This allows the close proximity of clownfish and sea anemones so that the sea anemones provide protection for the clownfish by stinging and deterring clownfish predators that come near and provide food by allowing the clownfish to eat the leftovers of what the anemone has consumed [2]. The clownfish provide better water circulation, rid the anemone of parasites, drop scraps of food for the anemone [4], and defend the anemone from butterfly fish that eat their polyps [6].

All 27 species of clownfish engage in this mutualism but only 10 out of 1,000 sea anemone species allow clownfish to live with them [2]. Of all the clownfish, Amphiprion clarkia (which is not Nemo) is the only species that can interact with all possible anemones[3]. They live in the warmer waters of the Pacific and Indian Oceans around Japan, Indonesia, northwest Australia, and along the southeastern coast of Asia [3]. A. clarkia can either live alone, in pairs, or in colonies within a single sea anemone, with the biggest in the colony being the dominant female, and the second largest being a male [6].

Description of the Relationship

The relationship between sea anemones and clownfish is a mutualistic relationship because both benefit from the relationship, providing each other with both food and reciprocal protection from their respective predators. Sea anemones can also form relationships with hermit crabs, but crabs carry anemones on their shells for their own protection and do not provide protection or food in return like clownfish do [6].

E. quadricolor, H. crispa , H. magnifica, M. doreensis, S. gigantea, and S. haddoni are among the sea anemone species that interact with clownfish [7], with Amphiprion clarkia being the most flexible and well-adapted clownfish to the anemones [3]. The relationship between anemones and clownfish has developed to be absolutely crucial to the survival of the clownfish since they are quickly eaten by predators when they are apart from their host anemones [1]. The reproductive fitness of the clownfish depends heavily on the protective quality of the anemo
nes’ stinging nematocysts, so if the ancestors of clownfish were free-living, it apparently became more beneficial for them to live within the confines of the protection of the sea anemones than to live freely on their own.

The relationship between the two is established by a juvenile clownfish seeking out the same species of anemone that their parents occupied, possibly through chemical signals and cues that were imprinted upon them as embryos [3]. The clownfish establish contact with an anemone by making quick contacts with anemone’s stinging tentacles and its belly. The tentacles actually sting the clownfish at first, but after several hours they become immune to the stings and venture into the anemone [3]. Once contact is established, the clownfish reside in the anemone and will even move with the anemone if the anemone b
ecomes distressed enough to relocate. The clownfish often stay within a radius of 2 meters of the anemone, since their chances of survival dramatically decrease if they venture away from the anemone [8].

Cost and Benefit

For the sea anemone, there seem to be no cost, since it gains increase in food availability and protection. The clownfish keep away butterfly fish that would otherwise consume their polyps; in fact, when clownfish were taken away from sea anemones in an experiment to see how long it would take the fish to repopulate them, the sea anemones were gone within 24 hours [9]. The clownfish also fan water around the anemone to increase circulation and the opportunity for the anemone to come into contact with a food source. Sometime, the clownfish will even seek out food to feed to the anemone. Additionally, they clean debris from the anemones by ridding the anemone of parasites and eating leftover food such as copepods, algae, isopods and zooplankton [2].

In a study carried out by S.J. Holbrook and R.J. Schmitt in French Polynesia over a three-year period, researchers determined that the presence of clownfish can have a significant impact on the physical condition of the anemone. Among their findings, they determined that anemones with fish grew 3 times faster than those that didn’t, they underwent asexual reproduction more often, and they had a lower mortality rate [5]. So there are direct correlations between the presence of the clownfish and the health and reproductive fitness of a sea anemone.

The clownfish also benefit extensively from their relationship with the sea anemones. They are provided with a food source when they are cleaning the anemone, and they are given protection from predators that are typically not immune to the nematocysts of the anemone. But, there is a slight cost to the clownfish; sometimes they will take their protective duties so seriously that they will engage in risky behavior in order to fend off predators of the anemone [2]. The clownfish will even try to ward off divers by trying to bite them, when a human is clearly much bigger and more dangerous to the fish. So by having a relationship where the fish risks it life for the anemone, a slight cost arises for the fish, but it is drastically outweighed by the protective service and food supply of the sea anemone.


Friday, March 18, 2011

Saharan Pest Control, Buphagus africanus/Buphagus erythrorhynchus


The species involved in this relationship are Oxpecker,Buphagus africanus or
Buphagus erythrorhynchus, and the Black Rhinoceros, Diceros bicornis. Oxpeckers are located across most of Africa while the Black Rhinoceros is located in the eastern and southern points of the continent. The Oxpeckers and the Black Rhinoceros usually mate near the ned of the rainy season. Oxpeckers usually nest in holes usually in trees and are lined with grasses and hair plucked from the host, The Oxpeckers can usually have 2-3 eggs per breed. [2]. Rhinos on the other hand have one calf after 15 months of incubation [3].

Description of Relationship:
The Buphagus africanus or Buphagus erythrorhynchus help the Diceros bicornis by eating ticks and other parasites off the body of the rhino. This helps keep the rhino clean while feeding the bird. This shows a mutualistic relationship. Not only does the rhino receive pest control, it also receives a warning system. When the rhino is in danger the oxpecker will take off or start making loud chirping noises which alert the rhino [5]. The oxpecker's role has resulted in the given Swahili name of "askari wa kifaru"; this translates in English to "the rhino's guard" [6]. The oxpeckers do not feed exclusively on rhinos, but they do feed exclusively on the backs of large mammals such as zebras, wildebeests, buffalos, and even giraffes.
Cost/Benefit Analysis:
Buphagus africanus or Buphagus erythrorhynchus
Feeding place
Diceros bicornis
Injury- It is believed that the oxpecker keeps wounds open by eat the blood and tissue surrounding the wound. This hurts the rhinoceros and prolongs the healing time [6].
Pest control


Thursday, March 17, 2011

Mutualism Between Humans and E.coli


Escherichia coli, commonly referred to as E.coli, is a rod-shaped bacterial germ that is found in the intestinal tract of humans and other warm-blooded animals. Although some strains of E.coli, such as E.coli O157:H7, can cause food poisoning and serious illnesses such as Hemolytic Uremic Syndrome, most strains are harmless and are part of the normal flora in the gut, providing beneficial Vitamin K to their hosts. [2]
E.coli's natural habitat is the gut of warm-blooded animals; however, they can survive outside host bodies in environments such as water or mud that are contaminated with fecal wastes. Due to its residence in warm-blooded animals, E.coli's global distribution spans throughout most continents in the world; however, the free-living species prefer warm places rather than cooler places.[3]
Fetuses of animals lack bacteria; however, immediately after birth newborns acquire various kinds of bacteria, including E.coli, through food or water or individuals handling the child. the bacteria travel to the bowels, where it attaches to the mucus of the large intestines and continues to grow.[4] The actual life cycle of E.coli includes both sexual and asexual reproductions. Asexual reproduction occurs through binary fission, while its sexual reproduction is achieved by conjugation between genetically differentiated strains. In mating E.coli, those with F+ or Hfr sex factors are male and those with the F- sex factor is female. A male and female collide by chance and the male transfers its sex factor to the female, completing conjugation. The male and female cells separate and the F- female becomes a partial diploid merozygote. The F- female cell then reproduces by cell division and returns to its monoploid state. Through theses to types of reproduction, E. coli are able to accumulate in the intestines of warm-blooded animals. [5]

Although this blog focuses on E.coli's relationship with humans, as previously stated, E. coli are also found to have similar relationships with other warm-blooded mammals and birds. As stated above, E.coli provide humans with vitamins, such as Vitamin K and B, that are necessary for development and healthy immune systems. [4] In our readings of The Art of Being a Parasite and Parasite Rex, and our class discussions, we know a that mutualistic relationship occurs when both organism are benefiting from the relationship. This relationship between E.coli and humans is mutualistic because while E.coli provide humans with necessary vitamins, humans provide a stable environment for E.coli to live, where they can feed off of the pathogens that come into the intestines.[3]

While there are some pathogenic E.coli strains, most of the strains that reside with humans are harmless. So, though we may come into contact with the pathogenic strains and become ill, the benefit of maintaining the bacteria within our intestines far outweighs the cost of getting sick from the pathogenic strains. Also, without E.coli residing in our intestines, we could not obtain the vitamins that are vital to our development and immune system functionality. Without these vitamins we would become ill anyways, so taking the chance of becoming infected with pathogenic E.coli, which can be cured with antibiotics, is far better than getting rid of beneficial E.coli that helps us dispose of harmful pathogens.

Although, E.coli can survive outside of their host, they cannot get the vast supply of nutrients or the safe environment that their host provides. The bacteria do face the risk of being identified as a pathogen and subsequently being destroyed by the immune system, but outside of the host it faces a environment that has a limited food supply and an unstable climate that would cause the bacteria to die, such as limited water supply.

Humans do not have strategies to encounter E.coli, however E.coli resides in reservoirs, such as water and food that people often drink and eat, so that they can easily be ingested and migrate to the intestines, consuming other pathogens that humans come in contact with and producing vitamins that benefit its host so that the E.coli can continue to have a stable environment.

[1]Joshi, Mohit. "Here's how E.coli bacterium causes illness." (2011) 16 March 2011. Web
[2] "Escherichia Coli."Wikipedia. 16 March 2011.Web
[3] "Escherichia Coli." MicrobeWiki. 16 March 2011. Web
[4] Brown, John C. "What the Heck is an E.coli?" Don't Touch That Doorknob: How Germs Can Zap You and How You Can Zap Back. New York: Warner Books, 2001. Web
[5] "Life Cycle of Escherichia coli." 17 March 2011. Web

Monday, March 14, 2011



There are many species of birds that follow massive assemblies of nomadic army ants that share a commensalistic relationship. The bird species include the White-tailed Ant Thrush (Neocossyphus poensis), Brown-chested Alethe (Alethe poliocephala), and Red-tailed Bristlebill (Bleda syndactyla)[3]. There are also several species of army ants including Dorylus wilverthi, Dorylus molestus, Labidus praedator, and Eciton burchelli [1,3]. As the army ants swarm across the forest floor in search of insects and arthropods, the birds follow along behind and eat the flying bugs the army ants stir up that the ant can not eat themselves. The birds benefit from the ants foraging, but the ants have little to no harm done to them. Army ant species have been found worldwide on a variety of terrains, although they are most common in tropical and subtropical regions between 45 degrees south and 45 degrees north [6]. Scientists have observed that where army ants reside, there are species of ant-following birds close behind.


There are four main families and types of ant-following birds: walkers (Cuculidae), climbers (Dendrocolaptidae), clingers and hoppers (Formicariidae), and perchers (Thraupidae).The largest group of regular ant followers is in the family Formicariidae, but there are more than 50 species that follow ants regularly [1]. These birds species include White-tailed Ant Thrush (Neocossyphus poensis), Brown-chested Alethe (Alethe poliocephala), and Red-tailed Bristlebill (Bleda syndactyla).[3] There are also several species of army ants including Dorylus wilverthi, Dorylus molestus, Labidus praedator, and Eciton burchelli, that are followed by a variety of birds listed above [1,3]. The army ants most likely evolved slowly from individuals to form such massive groups, after recognizing the greater success in predation [6]. Over time, army ants such as E. burchelli and L. praedator have become critical links between bird species and forest floor arthropods, providing food resources that would otherwise be unavailable for many birds in the leaf litter [4]. However, the birds are usually unrelated, and congregate around ant swarms randomly [5].



In this commensalistic relationship, the birds have the greatest benefit of following the army ants, while inflicting little to no harm on the army ants. The birds derive a benefit from the ants by eating the insects and/or arthropods disturbed by the ant “marches” through the forest. There is no break in food availability because ants swarm in almost all seasons and weather. [1] However, there is some cost for both. Birds do not intentionally try to harm army ants, but occasionally the insects the birds eat that were flushed out by the army ants already have army ants on them. Therefore, the army ants are ingested along with the insects, decreasing the fitness of those ants. A large flock of birds also occasionally takes more insects and/or arthropods than they should in order to not harm the ants’ own diet, which would bend towards parasitism [2]. However, only a small fraction of the total number of birds in a species follows ants, so the amount of food taken from the ants is minimal, bending back towards commensalism [1]. In addition, the ants are somewhat unreliable at high elevations and extreme hot or cold weather [1]. The army ants benefit slightly from the birds eating the excess arthropods because without the birds, the forest floor may become overrun with prey species.


[1] Willis, Edwin O., and Yoshika Oniki. "Birds and Army Ants." Annual Review of Ecology & Systematics 9 (1978): 243-63. Web.

[2] Wrege, Peter H., et al. "Antbirds Parasitize Foraging Army Ants." Ecology 86.3 (2005): 555-9. Web.

[3] Peters, Marcell K., and Benjamin Okalo. "Severe Declines of Ant-Following Birds in African Rainforest Fragments are Facilitated by a Subtle Change in Army Ant Communities." Biological Conservation 142.10 (2009): 2050-8. Web.

[4] Roberts, Dina L., Robert J. Cooper, and Lisa J. Petit. "Use of Premontane Moist Forest and Shade Coffee Agroecosystems by Army Ants in Western Panama." Conservation Biology 14.1 (2000): 192-9. Web.

[5] CHAVES-CAMPOS, JOHEL, and J. ANDREW DeWOODY. "The Spatial Distribution of Avian Relatives: Do Obligate Army-Ant-Following Birds Roost and Feed Near Family Members?" Molecular ecology 17.12 (2008): 2963-74. Web.


Sunday, March 13, 2011

Camouflaging Opportunity of Euprymna scolopes

Courtesy of:

Introduction: This blog examines the relationship between the Hawaiian Bobtail Squid and a bioluminescent bacterium. The Hawaiian Bobtail squid acquires an enhanced ability to capture prey and avoid predators, while the bacterium receives key nutrients from residing within the squid [2]. Distribution of this aquatic relationship is limited by the habitat of the squid (Hawaii). Several bioluminescent bacteria cycle through a single squid daily.

Description of Relationship: The type of relationship observed between Euprymna scolope(Hawaiian Bobtail squid) and Vibrio fischeri(bioluminescent bacterium) is unique to organisms with specialized structures called light organs. These light organs are specialized structures that have evolved to allow the organisms that house them to create light. While the evolutionary reason for this structure is unknown, many individuals hypothesize that certain marine organisms form these light organs through adaptation from dark environments in order to increase vision. By using Combes’ logic, this is a textbook example of a symbiosis (when individuals of two species whose evolution has previously been independent associate with one another so that each benefits) [3]. Justification for this statement will be discussed in the cost/benefit analysis section. The life cycle or interaction between these two partners is interesting. Each morning, a squid will eject the bacteria from the previous day and take in new/infant bacteria of that same species. Over the course of the day, the bacteria will multiply and be utilized by the squid at night. The next day the squid repeats this peculiar behavior of ejecting old bacteria and absorbing new bacteria [2].

Cost/Benefit Analysis: In this relationship, both organisms seem to benefit one another. By properly utilizing the bacteria to reduce its shadow from the moonlight, the Euprymna scolope is able to become a better predator to the prey below and evade its own predators through camouflage. Vibrio fischeri receive a special source of nutrition in the form of amino acids and other essential compounds that are provided to them via the Euprymna scolope’s light organ and bacteria are provided with shelter [4]. The extra weight the squid obtains from housing these bacteria, thus reducing their speed and more likely to be eaten by a predator, is a questionable cost. This cost seems to be outweighed by the beneficial ability the bacteria provide to squid. The squid does not appear to exert any recognizable cost on the bacteria.






[3] Art of Being a Parasite, Claude Combs



Wednesday, March 2, 2011

Toxoplasma gondii: Parasitic Mind-Control

Toxoplasmosis is a leading cause of death attributed to food-borne illness in the United States. While a large number of people carry this disease, few actually experience symptoms, as a result of strong immunity. Nonetheless, in the case of the immunodeficient, it can be devastating. Most cases are passed from mother to child; when contracted during pregnancy, the infection can be detrimental and even fatal to the fetus.

This infection is caused by Toxoplasma gondii (T. gondii). A single-celled protozoan parasite, it can be a symbiont of most warm-blooded animals, but its definitive host is the cat. It is commonly contracted by humans through consumption of undercooked meat which have been an intermediate host to the parasite. [1] Image: [1]


T. gondii is the only species belonging to the genus Toxoplasma. It is a single-celled protozoan parasite. A member of the phylum Apicomplexa, this parasite has an apical complex used for borrowing into host cells and for reproduction. The apical complex can also be used for secretion of compounds that aid in attachment and penetration of the host. While T. gondii lacks flagella or cilia, it is able to move by way of cell crawling. The parasite uses a few methods of manipulation in order to protect itself and to ensure progression from intermediate hosts, like mice, to the definitive host, the cat. [2] image: [2]


T. gondii lives inside mammal hosts throughout most of its life.
It can be hosted by most warm-blooded animals. The parasite completes its sexual stage inside its definitive host, the cat. Here, sporozoites are spread from intestinal epithelial cells to virtually all cells of the cat's body. Oocysts are excreted in the fecal matter of the cat. Intermediate hosts include other animals like birds, rodents, and humans; animals bred for human consumption or wild game can also be infected by ingestion of oocysts found in the environment. [3] image: [4]

Life Cycle

T. gondii oocysts are found in the feces of cats. They are usually only shed for one or two weeks. It takes between one and five days for the oocysts to sporulate and become infective. Intermediate hosts (birds, rodents, or animals bred for human consumption/wild game) ingest material that has been contaminated by feline waste, including soil, water, or plants. The oocysts become tachyzoites after ingested, and concentrate in muscle and neural tissue, where they form cysts. Intermediate hosts can be consumed by cats or humans. Cats and humans can also directly ingest sporulated oocysts from contaminated sources of water, food, or soil in the environment. Humans are highly at risk when they come in contact with feline waste by changing a litter box. The parasite can also be transmitted through blood transfusion, organ transplant, and most commonly, from mother to child at birth. [1] image: [1]


T. gondii causes the disease Toxoplasmosis, which is found worldwide. Over 60 million Americans are infected [2]; between 30% and 50% of people worldwide are infected. It is most commonly passed along through pregnancy. [4] There is a higher prevalence in European countries like France and Germany, with around 88% of the population is infected. This is believed to be due to higher consumption of raw/undercooked meat in those countries. [5] There is also a higher prevalence in Central America, which may be due to a higher occurrence of stray cats combined with a climate that favors oocysts and soil exposure. [6]

While there is such a high prevalence of infection, very few people actually have symptoms. Most people who show symptoms have low immunity; toxoplasmosis is usually self-limiting. It can, however, be seriously detrimental or even fatal to the immunocompromised, or to fetuses of a mother who first contracts the illness during pregnancy. [1] In the case of congenitally infected children, it can lead to blindness or mental retardation. [7]

This infection is commonly associated with impoverished people, and is thus considered a "Neglected Infection of Poverty" (NIP).[1]

From a socio-economic standpoint, the cost of care of sick children is exceedingly expensive. In some European countries it is required that pregnant women are tested for this infection. This raises the debate of the potential cost and benefit of mandatory testing. If a woman is tested and finds she has not yet contracted this infection, she can learn precautions to take in order to prevent infection while pregnant. [7] image: [4]

While most people will not experience them, symptoms are usually similar to those of the flu or mononucleosis. In patients with low immunity, more severe symptoms can be found, such as headache, confusion, poor coordination, seizures, blurred vision, and a lung problem similar to tuberculosis or Pneumocystis carinii pneumonia (an opportunistic infection effecting people with AIDS).

When pregnant women are infected, the fetus is most at risk of contracting an infection during the third trimester. However, the earlier the infection is contracted, the worse the symptoms will be. Most early infections lead to stillbirths or miscarriages. If the baby survives, symptoms can include seizures, enlarged liver and spleen, jaundice, and eye infection.

When contracted from their mothers, many babies will not show symptoms until later in life (usually teenage years). These symptoms include hearing loss, mental retardation, and eye infections that could lead to blindness. [8]

In order to prevent infection through ingestion of meat, all meat should be fully cooked to recommended temperatures, and even frozen for several days ahead of time. Fruits and vegetables should be washed and peeled before eaten. Kitchenware should be kept clean and sanitary, and as always, normal hygiene rules, such as washing your hands, apply. It is recommended that you do not drink untreated water in order to avoid infection. When gardening or working with soil, gloves should be worn. Litter boxes should be changed daily, since the parasite becomes infectious from one to five days after eggs are shed. Pregnant women should avoid changing litter boxes or handling stray cats. [1]

Pyrimethamine (Daraprim) is an antimalarial medication. When used in conjuction with Sulfadazine, it can be used to treat toxoplasmosis. In most cases, patients will have to take these medications for life. If a pregnant woman becomes infected, Spiramycin is an available medication for treatment and can possibly prevent fetal contraction of the infection. [8]

An Example of Host Manipulation

T. gondii can manipulate it's host in order to both protect itself, and ensure progression to its next host. For protection, it encysts itself and then releases a substance that increases the host's concentration of T cells. This improves the host's immune response, killing other T. gondii parasites, except those that are protected by cysts. This ensures that the host will not become overrun and die from the parasite, thus acting as a "home-security" strategy for the parasite.

This parasite can also alter its host's behavior. It causes mice to be less afraid of cats' scents- mice are ordinarily programmed to avoid these scents. T. gondii can sometimes even cause mice to be attracted to or seek out the scents. This ensures that the parasite makes it to the definitive host. [2]

video: [9]