Toxoplasma Gondii in Feline Cats: Analytical Essay

Abstract

Toxoplasma gondii is a severe eukaryotic parasite from the phylum which infects up to one-third of the world population. Although most infections are asymptomatic, some cause tumours which form in the eyes, and can lead to life threatening complications, infections affecting the central nervous system in homo sapiens when contracted through the womb or picked up through faeces. Parasites can reach a persistent condition resistant to current therapies, which may act as a reserve system for the condition. Feline Cat are a number one hosts for Toxoplasma Gondii, in which parasites may grow together forming oocysts that are highly infectious and are very immune to environment. Majority of all warm blooded animals may serve as intermediate hosts and require the infection from oocysts or tissues.

Statistics shown that in the United states 11% of the population have been infected with Toxoplasma Gondii at the ages of 6 years and older. 60% of the world population has been infected with the parasite called toxoplasma. Usually in the hot climates is where oocysts survive better and last longer. This infection isn’t passed from human to human except it is passed by Animal to Human as well as Mother to child. Oocysts quickly turn into a cell called tachyzoites after the host has ingested the parasite.. Cats usually become infected when they digest rodents which are transferred into humans from cleaning up cat litters.

Introduction

Since the 1920s doctors have advised women who are pregnant who became infected by this parasite that the fetes could be infected as this parasite would be transmitted in some cases it could cause brain damage or death. The set reasons as of why this topic had been the main topic of discussion for my dissertation is, I have always wondered why homo sapiens have always had an interest and loved feline cats. As a child I never got to own a cat myself but I did have friends who had cats. In year 12 I was studying for my biology A-levels in the library and I came across a book which told me about toxoplasma Gondi, I was quite shocked and impressed at the fact that such amazing cats could cause us so much damage this inspired my thoughts to talk about this topic. Toxoplasmosis is referred to a disease which is caused by an infection by single celled microscopic parasite called toxoplasma Conti disinfection is spread throughout the world in feline cats, raw soil and outdoor. This parasite rarely causes infection in it is infected host. 20% of cats world’s population of cats are infected with this parasite. Humans generally become infected by eating undercooked meat of animals who had the cyst, consuming food or contaminated water with the cat faeces around or generally just changing cat litter box of their pets in their homes. Toxoplasma gondii is a parasite which infects animals and humans which causes a disease called toxoplasmosis. The main host are domestic cats and their relatives. Toxoplasma gondii is known as one of the worlds powerful parasites in the world. This parasite can survive in any climates artic or hot areas weather it is an isolated town or a large city this parasite will always be successful. Toxoplasma gondii is a very prevalent parasite in the worldly population. Usually one third of the population is infected. Animals which have warm blood are usually great immediate host for the parasite. Toxoplasma gondii has been found in many pig tissues from farms. It has been calculated that the number of Toxoplasma gondii cysts per gram of food animal tissue, such as swine, could be less than one tissue cyst per 50 g. although the concentration on the bioassay technique is used 7 In which is used for the technique, the procedure is tedious and very expensive which is seen to be potentially dangerous and expensive.

A 60 year old man had A light headache and numbness on the left side of his head and fatigue. Three years go on and the man was diagnosed with urinary bladder tumour. Transurethral resection of the tumour was treated with post-resection instillation of six-dose mitomycin C. The patient recovered fully and was followed up without further medication.

This image from life cycle of toxoplasma gondii illustrates the classic immediate host of rodent to soil to cat which is a mechanical transmission route for the parasite to extend.

Toxoplasma gondii is very common in the wildlife as there are many rodents who find new hosts by being eaten by warm blooded animals.

Aims & Hypothesis

• Glutamate is an amino acid that is produced from nerve cells or neurons. It is one of the most common excitatory neurotransmitters in the brain, helping to interact with neurons. Previous studies have shown, however, that too much glutamate will cause harm; glutamate build-up is frequently seen in persons with traumatic brain injury (TBI) and in people with other neurodegenerative disorders, such as multiple sclerosis (MS) and amyotrophic lateral sclerosis (ALS).
• Scientists note that excess glutamate accumulates beyond the nerves, and this build-up is managed by astrocytes – cells in the central nervous system (CNS). Astrocytes use a glutamate transporter named GLT-1 to absorb excess glutamate from outside the neurons to turn it to a less toxic compound called glutamine that cells use for energy.
• The author had said “When a neuron fires, it releases glutamate into the space between itself and a nearby neuron,” explains Wilson. “The nearby neuron detects this glutamate, which triggers a firing of the neuron. If the glutamate isn’t cleared by GLT-1 then the neurons can’t fire properly the next time and they start to die.” So, this led me to doing some more research and finding out that the mice infected with T. gondii the scientists found and increase in glutamate levels. So furthermore, the parasite is being prevented by GLT-1. This is caused by accumulation of glutamate of neurons. This could lead into a very fatal death or neurodegenerative disease. “These results suggest that in contrast to assuming chronic Toxoplasma infection as quiescent and benign, we should be aware of the potential risk to normal neurological pathways and changes in brain chemistry.” Written by Emma Wilson. The other researchers infected the mice with antibiotics called ceftriaxone. In which was shown to help benefit the mouse infections. Antibiotics were improved by production of the GLT-1 which happened to decrease the build – up of the glutamate or restore of neuronal activity. A more direct way of research needs to be performed to understand the real deal of this very common pathogens which remain in the world. Even though the findings have been linked between the infection T.gondii and neurodegenerative disease .
• Exploiting a high versatility and following human movements the household feline cats has colonized a wide assortment of territories, running from urban zones to non-anthropized islands, though, rural regions, bone-dry or semi-dry zones, towns or urban areas, from polar to central climatic locales. In any case, because of the conduct versatility of this species, populace thickness and structure differ, contingent upon the wealth and appropriation of nourishment assets and sanctuaries. Specifically, feline populaces are organized distinctively along a urban-rustic non-anthropized (‘wild’) slope . The most elevated densities of felines are found in urban populaces of stray felines locally in excess of 1000 felines. At these high densities, felines structure enormous multimale–multifemale social gatherings and offer their domain, just as accessible assets. Most assets are given legitimately or not, by individuals (feeders, trash). In country territories, populace thickness is moderate (100-300 felines. Most felines have a proprietor who gives nourishment and safe house however felines are commonly allowed to wander . A significant piece of felines diet result from predation: 15 to 90% contingent upon feline way of life. In provincial regions, the spatial dissemination of felines depends on human settlements: the social gatherings depend on a house or ranch that gives the vast majority of the taking care of and settling assets. Around a taking care of point, felines may frame gatherings of up to 20 people, regularly established by related females and their cats. Truth be told, in such territories, an inclination can be seen between pet-possessed felines for the most part took care of by the proprietor, to cultivate felines and non-domesticated felines for the most part living on predation. At long last, non-domesticated felines involving non-anthropized zones (sub-Antarctic, dry or forested regions), endure only through predation, live at low thickness in huge and non-covering home reaches .
• One third of the world population of 7 billion people are estimated to be infected with toxoplasma gondii. The human immune system can work with the parasite so only a small percentage have experience zero to non-symptoms. This parasite includes devastating damages into the human brain, eyes and nervous system. A small minority of the world population have subtler symptoms triggered by the parasite. This causes collateral damage in which produces neurotransmitters dopamine which changes the behaviour of the human brain, the leady authority on toxoplasma gondii Rima McLeod professor of ophthalmology asked “what do we think happens when billions of people go through life with a parasitic brain infection?” this is why I have chosen to discuss and find out in depth what actually happens.
• 30% to 50% of the world population are infected of this parasite which leaves devastating effects on the human brain. In 2012 the centers for Disease Control and Prevention where measured around 60 million people who were infected are between women, men and children. People usually contract this deadly parasite by eating raw meat in most occasions. The CDC have said that toxoplasmosis is a main leading cause of foodborne illness in the US. Other ways Human contract this parasite is through cat faeces or changing the cat litter, Majority of the population who are infected were infected have minor symptoms such as: nausea, mild flu symptoms which slowly enters a chronic dormant phase. Although, some people who suffer from weaker immune systems it could become fatal.
• Studies have found that mental health issues such as depression, anxiety and schizophrenia these are very commonly found in people with Toxoplasmosis, there is evidence that this parasite is linked extrovert and risk – taking behaviour. A study which was published in July 2012 ‘archives of psychiatry researchers from Denmark’s statens serum’ studies showed that women which carried igG antibodies to toxoplasma gondii had a higher chance of risk of self-harm in the near future. This study was very disturbing and alarming it showed that “At the same time, it’s important to emphasize that humans have lived with this parasite for many millennia, so today’s carriers of Toxoplasma need not be particularly worried.” This was said by a researcher Antonio Barragan at the center for infectious medicine at Karikinska institute. The researchers didn’t find out whether toxoplasmosis parasite changed the chemical messengers which carried the signals. Toxoplasmosis parasite isn’t examined on how it changes the host behaviour the researches were introducing what it did to the brain. Researchers also found out that the brain neurotransmitters are taken over by the parasite which affects the chemical messengers that carry signals between many parts if the brain. Toxoplasma gondii is a very serious parasite which is very successful in infecting its host, this infection has been linked to mental health in humans such as suicide attempts, schizophrenia or an imbalance in human personality. The human main source of contact is through the faeces of infected animals, which are usually domestic cats. The parasite completes its life cycle when humans are infected. In rare cases this parasite can present symptoms such as: myocarditis and meningoencephalitis. Although majority of infected humans show no symptoms. Toxoplasma gondii disease wellbeing noteworthiness with the exception of in instances of simultaneous immunosuppression, for example, HIV contamination. In any case, ongoing reports have proposed that disease with Toxoplasma gondii may have beforehand unrecognized outcomes in people. One such consequence relates to manipulation of host behaviour. In terms of the intermediate-to-definitive host relationship, modifying normal interactions between the two would be advantageous to the transmission and reproduction of the parasites. In other words, modifying the normal aversive reaction of a rodent to the felines would be beneficial to the parasite Since it would generate a greater chance that the cat would consume it, the organism in which the life cycle of the parasite is completed. I have found evidence that mice are infected with T. Gondii predicts innate loss of cat urine fear and impaired operating memory. These observations have led to the hypothesis that the rodent hosts might not be unique to such manipulations, As such, the extrapolation of these observations to human behavioural factors is gaining interest.

Human behaviour has been focused highly on domains which include psychosis and impulsive behaviour. High demands of research on the parasite shows a lot of humans are affected by schizophrenia. Positive individuals of psychosis were tested positive in the 1950’s. 38 studies have been founded of meta- analysis studies which suggests that the increase of toxoplasma gondii infection increases the chances of developing schizophrenia by 2.7 times. However, the comparison suggests that toxoplasma gondii has a major effect on depressive disorder. One case was reported and demonstrated that depressive symptoms were relieved by symptoms medication for Toxoplasma gondii whilst another case I found said that cat bites and scratches increase a women chances of depression. Although studies of the parasite which are linked with depression are inconsistent. Imbalance in human mood swings and violent behaviour is another potential effect the infection has on humans. Infected women are found to be aggressive whilst infected males are found to be very impulsive. Complementing these individual level research, cross-sectional comparisons have reported the positive association between sectional seroprevalence levels of Toxoplasma gondii antibodies titters and higher national suicide and homicide rates. Another research documented an increased incidence of zero- among prisoners relative to controls. However Foodborne diseases were caused by the number of bacteria, virus and parasites which travel around the world, this leads to infection passed through the host. In many countries the foodborne parasite are usually protozoa which is cryptosporidium. Flatworms is a common zoonotic parasite just like toxoplasmosis which is the infection caused by toxoplasma gondii. The parasite can’t grow outside of a host that isn’t a human body or feline. In some food types some findings show that toxoplasma gondii can be transmitted by indigestion of oocysts from the contact of the cat faeces. this parasite can survive up to 2 years in the soil. Oocysts are very infectious to herbivores. Oocysts are very contagious to herbivores, as are bradyzoites to animals. There are three levels of T Gondi they occur in groups. Tissue cysts such as bradyzoites and in oocysts such as sporozoites. Biological life cycle T. Gondii is known in the sexual and asexual stages The sexual cycle is confined to the feline intestine which contributes to the secretion of oocysts in cat waste. Enabled oocysts (cat excretion) are highly contagious and can survive in the atmosphere for a long time (several months) and probably years. The asexual process is triggered when some other warm-blooded species ingests these contagious oocysts.

People who handle food are usually called distributors, housewives, butchers or farmers. Or preparation or production teams of food who don’t have direct contact to the food but handle the food. In most cases the main source of transportation is usually human beings as they get around to walk and travel around a way of preventing contamination is to practise safe compliance by handling food with proper care and prevention. Researches have examined that even though the parasite toxoplasmosis in healthy humans are asymptomatic, it always seems to cause problems which could potentially become fatal in the individuals at any age. HIV/ AIDS patients always have a fatal risk of death imposed if this infection has been transported to them. If consumption of the meat is contaminated with feline faeces may cause transplacental infecting that could infect the pregnant women. Studies have shown that 30% to 90% of the infection rate of Toxoplasmosis in central and south America are infected. The disease of mortality has risen, The Netherlands had an increase of 620 for disability adjusted life years which was similar to the united states which was reported in some middle eastern low income countries too. T. Gondii is prone to heat inactivation and experiments have shown that heat can kill T. Gondii oocysts.

Type of methods Temperature(s) (°C) Time (min/h/day) Main finding Ref.

1. Heating 50 2.5 min Sporulation of Toxoplasma oocysts inhibited. [65]
2. 50 30 min Infectivity of sporulated oocysts disappears. [65]
3. 55 30 min Tissue cysts are destroyed. [66]
4. 58 30 min No evidence of parasites in infected murine brains. [67]
5. 58 15 min Sufficient to inactivate all oocysts. [67]
6. 61 3.6 min Tissue cysts were generally rendered nonviable. [75]
7. 60 or 100 1 min No viable T. Gondi infective stages isolated from meat samples. [76]
8. 63 30 min T. Gondi tachyzoites RH strain die in pasteurized milk. [77]
9. 75 1 h Heat treatment like boiling water can inactivate T. Gondi oocysts. [78]
10. Cooking 63, 71, 82 – Beef, lamb and veal roasts and steaks should be cooked to at least 63°C. Pork, ground meat and wild game should be cooked to 71°C before eating. Whole poultry should be cooked to 82°C in the thigh to ensure doneness. [27]
11. 67 – Tissue cysts in meat are killed by heating meat throughout. [61]
12. 50 1 h Heating inactivates tissue cysts. [73]
13. 67 0.01–96 min Kills tissue cysts in meat. [79]
14. 66 – Heating meat throughout to reach a temperature is sufficient to kill cysts in meat. [80]
15. Freezing and low temperature −12.37 11.2 day Nonviable T. gondii tissue cysts in pork upon freezing. [61]
16. −20 1–2 day Tissue cysts stored at −20°C could infection after 24 and 48 h of storage. [81]
17. −21 1 1/2 h After 1 1/2 h of exposure to −21°C, many cysts seem to lose their infectivity. [62]
18. −10 or −20 3 day Freezing of meat at −10°C for 3 days or at −20°C for 2 days killed parasite and cysts could not recover. [76]
19. −7 4 day Inactivation of T gondii tissue cysts was achieved by freezing at −7°C for 4 days. [82]
20. −20 21 day Sporulated oocysts were inactivated by freezing. [82]
21. −20 2 day Freezing for 2 days at −20°C was sufficient to inactivate parasite. [72]
22. −25 6–35 day Experiments with meat from pigs fed with T. nondisinfected mice showed that all meat samples were rendered non-infectious. [83]
23. −7−12 4 day Parasites in meat from experimentally infected pigs did not survive. [82]
24. −20 3 day Temperature and time required to inactivate isolated tissue cysts. [81]
25. Elizadeh, a., 2020. [online] A review on inactivation methods of Toxoplasma gondii in foods.