Investigating the determinants of Toxoplasma gondii prevalence in meat

Annotated Bibliography

Belluco, S., M. Mancin, D. Conficoni, G. Simonato, M. Pietrobelli and A. Ricci (2016). Investigating the determinants of Toxoplasma gondii prevalence in meat: A systematic review and meta-regression.
PLoS One, 11(4).
The complete sexual cycle of Toxoplasma gondii occurs in felids but contamination can also occur by the dispersion of the infective oocysts in the environment.  These oocysts can be found in most animals and can be transmitted to humans when the infected meat is consumed. The prevalence of this parasite is different in animals. For instance, pigs and sheep have a higher prevalence than cattle. This article contains enough information about the life cycle of Toxoplasma gondii to give a general background of how this parasite reproduces and infects humans. I will also include the variety of animals that the parasite uses to get to its definite host showing how this parasite has low host specificity. Moreover, the article provides information on how humans get infected by ingesting the oocyst, which provides one way that humans can get infected. Finally, I will use the ways to prevent getting infected by not eating certain meats that are highly susceptible to contain this parasite.

Chavez-Munguia, B., L. S. Villatoro, M. Omana-Molina, M. A. Rodriguez-Monroy, N. Segovia-Gamboa, A. Martinez-Palomo (2014) Naegleria fowleri: Contact- dependent secretion on electrodense granules (EDG). Experimental Parasitology. 142: 1-6.
Naegleria fowleri is a parasite that causes primary amebic meningoencephalitis. This parasite penetrates the nasal mucosa and travels to the brain where it causes cerebral hemorrhagic necrosis. Using transmission electron microscopy, scientists found a high concentration of electrondense granules in the amoebae being tested. These results showed that electrondense granules have a role in the cytopathic mechanisms of the parasite. I will use this article to provide information of where the parasite is found and how it penetrate the nasal cavity of humans to reach the brain. I will also include the fact that trophozoites degrade extracellular matrix proteins and destroy cells. Finally, I will be adding the study performed in this article based on the high levels of EDG were found in different amoebae species which correlates to the activity of the parasite in the brain of the host.

Fekadu, A., T. Shibre and A. J. Cleare (2010). Toxoplasmosis as a cause for behaviour disorders - overview of evidence and mechanisms. Folia Parasitologica, 57(2): 105-13.
Toxoplasma gondii can be one of the main causes of various psychiatric conditions. This parasite can affect the brain in acute and latent stagens. It can change the behavior of the host and thus cause many mental disorders. T. gondii causes many changes in neuroimmunomodulation, neurotransmission and interaction between genes. There’s evidence that this parasite may be the cause of many behavioral disorders and it might lead to new treatments and prevention for patients suffering from mental disorders.  This article provides overall information on how this parasite affects the human brain and the behavior of the host. I will use this to explain the effects of the parasite and how it might be connected to many cases of mental disorders. I will also include the statistics of the infected population and compare it to those that have a mental disorder. Finally, I will also include the ways we can prevent these disorders and how to treat them if this parasite was the cause of the illness.

Flegr, J., J. Prandota, M. Sovicková and Z. H. Israili (2014). Toxoplasmosis - A global threat. Correlation of latent toxoplasmosis with specific disease burden in a set of 88 countries. PLoS One, 9(3)
Toxoplasmosis is generally asymptomatic for healthy people but can be serious for those that have low immunity and can be more prevalent in the elderly. These asymptomatic infections can lead to other human pathologies that are more serious thus it is essential to know who is more susceptible to this disease in order to be treated. Pregnant woman can become infected and cause a miscarriage due to the transplacentally transmission from mother to fetus. Moreover this disease can also be transmitted through blood transfusion and organ transplant. This article provides a lot of information on the epidemiology of Toxoplasma gondii, which I will be using to explain the consequences of obtaining this parasite and who is more susceptible and is in more danger. The article also provides a list of countries where this parasite is found the most and where more cases are found, thus I will be adding the locations and statistics of mortality or survival of the infected hosts. I will also use the information on the cellular mechanism of infection to compare and contrast the other parasites’ mechanisms in my paper. Finally, I will incorporate the results that show how this disease may lead or develop to other human pathologies.

Garcia, H. H., A. G. Lescano, I. Gonzales, J. A. Bustos, E. J. Pretell, J. Horton, H. Saavedra, A. E. Gonzalez and R. H. Gilman. 2016. Cysticidal Efficacy of Combined Treatment With Praziquantel and Albendazole for Parenchymal Brain Cysticerois. Clinical Infectious Disease. 62: 1375-1379.
Albendazole and praziquantel are antiparasitic treatments for Taenia solium. These two treatments use different mechanisms of action to remove the parasite from the host, but using both at the same time will improve the efficacy of removing the parasite. This antiparasitic medication damages the cysts of the parasite found in the brain and also exposes antigens, and changes the mechanism that the parasite uses to invade the brain. This allows the immune system to attack the parasite. Combined medications will have a higher impact on the immune response of the host towards the parasite. This article explains thoroughly how this parasite attacks the immune system of the host, which is useful to compare the other parasites. I will also mention the medication given for this parasite and how it works in comparison to the ones used for the other parasites. Moreover, I will use the results to talk about the new enhanced treatment for Taenia solium. Finally, the article also provides an explanation on how the combination of both medications is better than using ABZ alone, which is new useful information to add to my paper that most of us don’t know about.
Ho-Cheol, Y., P. Soon-Jung, K. Hyun-Hee and C. Dong-Il. 2002. Isolation of genes induced in Naegleria fowleri during mouse brain passage. European Journal of Protistology. 38(2): 105.
Naegleria fowleri invades the brain of the host causing extensive necrosis, which leads to a fast death. Various factors of phagocytic activity are responsible for the inflammation and hemorrhages that this amoeba causes in the brain. The gene expression of the amoeba may change during host infection, affecting the virulence of the parasite. The genes HMG and the 26S proteasome subunit were examined in this experiment and results showed that they may be involved in the cellular mechanism during the host’s infection. This article will be used to add more information on the mechanism that this parasite uses to control the brain of the host. It also provides a short explanation of how the host becomes infected. I can use this article to compare the other parasite’s genetic expression with this one. Finally, it provides information on how this parasite causes immediate death of the host which is important to note that it is the most dangerous parasite from the others that I will be talking about.

Schantz, P. M., Moore, A. C., Muñoz, J. L., Hartman, B. J., Schaefer, J. A., Aron, A. M., Flisser, A. (1992). Neurocysticercosis in an Orthodox Jewish Community in New York City. New England Journal of Medicine N Engl J Med. 327(10): 692-695.
Taenia solium is also known as the pork tapeworm and it is known for causing an infection of the central nervous system known as neurocysticerosis. This intestinal tapeworm causes autoinfection of the host where the infectious state, the cysticerci may be found throughout the body but it is more deathful when found in the central nervous system. In order to obtain this tapeworm, the host must eat the infectious state, which is typically transmitted by undercooked pork. The Jewish community of New York City had a case of this tapeworm, which was very unusual due to their culture rules showing that there are other ways to obtain this parasite. I will use this article to describe how this parasite causes autoinfection and how its infectious stage can end up in the host’s brain. I will also use the information on how this parasite is transmitted to their host by using the example of the Jewish that didn’t obtain it by eating undercooked pork. The article also provides information of other areas where this parasite is found, which can be useful to compare to the other parasites. Finally I will describe the epidemiology and treatments in comparison to the other parasites.

Trevisan, C., E. M. Mkupasi, H. A. Ngowi, B. Forkman, M. V. Johansen. 2016. Severe seizures in pigs naturally infected with Taenia solium in Tanzania. Veterinary parasitology. 220: 67-71.
  Pigs infected with Taenia solium were tested to check if this parasite does indeed cause seizures on the pig. After conducting the experiment, the results showed that most pigs suffered from trembling, twitching, paralysis and eye blinking. The pigs were then slaughtered to dissect their brain to find the cysticerci that were causing these seizures. This experiment can introduce other studies to explore the neurological symptoms in humans caused by this parasite. I will use this article to explain the causes of this parasite in the pig and humans. Showing the experiment will give the reader an idea of how serious this parasite is and how essential it is to avoid eating undercooked meat. I will also use this article to show how it affects the pigs, thus affecting the economy of many farmers that have to avoid selling their unhealthy pigs. Finally, I will use this article to explain how the parasite shows autonomic and motor signs during seizures, which is a completely different symptom from the other parasites.