How Toxoplasma in humans turns aggressive

Posted on August 24, 2016 by Douglas Powell

USDA’s AgResearch Magazine reports that Toxoplasma gondii is a parasite that has infected an estimated one-fourth of the world’s population—potentially more than 1 billion people—including about 50 million in the United States. This makes T. gondii the most widespread parasite in the world. This one-celled parasite, invisible to the naked eye, causes a human disease called “toxoplasmosis.” It can lead to serious health complications in people with weakened immune systems and in infants born to infected mothers. Prevention is key.

T. gondiiinfection can happen in two ways. Cats are the only animals that shed the parasite’s egg-like sacks (cysts) in their feces—thus exposing humans and other animals to infection via contaminated soil, water, food, or litterboxes. Infection can also take place when people consume undercooked meat containing T. gondii.

Agricultural Research Service (ARS) scientists and colleagues completed a study that provides clues about T. gondii’s virulence and spread. The study describes genetic mechanisms that help a mild-mannered T. gondii strain turn aggressive.

For the study, a consortium of international researchers, including zoologist Benjamin Rosenthal and parasitologist Jitender Dubey, both with the ARS Parasitic Diseases Laboratory in Beltsville, Maryland, contributed strains of T. gondii from more than a dozen countries spanning the Americas, Europe, Africa, and Asia. The researchers conducted a genomic analysis on each of 62 strains and identified several types of proteins, called “secretory pathogenicity determinants” (SPDs) that thwart the hosts’ immunity.

Secreting SPDs enables the parasite to influence and hinder host defenses. “These proteins enhance the parasite’s survival, which in turn affects disease severity in hosts,” says Rosenthal. “SPDs have diversified more in T. gondiithan in species closely related to T. gondii, so we are very curious to learn more about the functions they perform and their relationship to disease.”

The findings are helping researchers to identify the genetic basis for differences among strains of T. gondii, from mild strains found in U.S. farmlands to more virulent strains found in the jungles of Brazil and French Guyana. The researchers found that T. gondii strains could become more aggressive through environmental adaptation.

In healthy people, infection does not necessarily mean a person will become sick or develop symptoms. The study results provide valuable information about a subset of regulatory genes that enable the parasite to infect animals and humans. The findings will help researchers develop new treatments and methods to check the parasite’s ability to spread.

Check the pork; cluster of toxoplasmosis in Brazil

Posted on March 7, 2016 by Ben Chapman

It’s not just for cats anymore.

In 2012, Hip-music-listening, and general all around good guy Mike Batz (and co-authors) identified Toxoplasma gondii and pork as the second most burdensome food-pathogen combination, resulting in an estimated 35,000 illnesses annually in the U.S.

At least 20 Brazilian cases of toxoplasmosis have been confirmed with another 70 showing symptoms according to Folha Geral (some things may be lost in translation).

Five months after identifying an outbreak of toxoplasmosis in the premises of the Agronomic Institute of Paraná (Iapar), in the south of Londrina, the Department of Epidemiological Surveillance of the Municipal Health Department yesterday confirmed another outbreak, this time in the unit of the Brazilian Agricultural Research Corporation (Embrapa), located in the district of Warta, in the north.

According to the manager of Epidemiological Surveillance Londrina, Rosangela Libaroni, 73 people showed symptoms of the disease transmitted by the feces of cats between the end of last year and the end from January. The tests confirmed 20 cases of acute toxoplasmosis and dismissed another ten. The rest of the cases still under investigation follows awaiting official reports. Three patients presented symptoms but were not contaminated.

The task force set up to try to identify the source of contamination has a partnership with the State University of Londrina (UEL). The head of the Department of Preventive Veterinary Medicine UEL, Italmar Navarro, said the research follows in the analysis phase, but said that the contamination through the water was discarded. He also recalled that there was no conclusion about the focus of contamination that caused the outbreak in Iapar late last year after a series of laboratory tests.

Yesterday afternoon, the troughs of Embrapa who were sealed were reactivated. Already the cafeteria remains interdicted. Rosangela reported that all the people who have been infected will be heard to see if they were eating at the local cafeteria. “If it is not the water, suspicion falls on the food. We have to know the origin of this food, because of the outbreak of risk elsewhere in the city,” Rosangela warned.

My cats are killing me: Toxoplasma linked to mental illness, schizophrenia

Posted on June 7, 2015 by Douglas Powell

People are told moms-to-be shouldn’t be cleaning the cat litter because of the risk of Toxoplasma gondii, so with five daughters, I’ve just gotten used to cleaning the litter.

Turns out my cats are killing me.

And making my kids crazy.

We used to have a sandbox when the kids were young, but the cats always viewed it as a giant litter box.

So the kids stopped using it.

Toxoplasma gondii is the most common parasite in developed nations, according to Schizophrenia Bulletin. The cat-carried parasite can infect any warm-blooded species, and the Centers for Disease Control and Prevention estimates more than 60 million people in the U.S. may have it.

Most people never suffer any symptoms at all. But in those with weaker immune systems, infection with T. gondii can cause an illness called toxoplasmosis, which can result in miscarriages, fetal development disorders, weeks of flu-like illness, blindness and even death. It has also been associated with mental disorders including schizophrenia and bipolar disorder. Now two more studies explore the mental health issues in greater detail.

E. Fuller Torrey of the Stanley Medical Research Institute and Dr. Robert H. Yolken of Stanley Laboratory of Developmental Neurovirology at the Johns Hopkins University School of Medicine have been studying the link between infection with T. gondii and schizophrenia for close to three decades.

Their most recent study, published in Schizophrenia Research, along with researcher Wendy Simmons, compared two previous studies that found a link between childhood cat ownership and the development of schizophrenia later in life with an unpublished survey on mental health from 1982, 10 years before any data on cat ownership and mental illness had been published. Results of the analysis indicated that cat exposure in childhood may be a risk factor for developing mental disorders.

“Cat ownership in childhood has now been reported in three studies to be significantly more common in families in which the child is later diagnosed with schizophrenia or another serious mental illness,” the authors reported in a press release.

In a second recent study, A.L. Sutterland from the Department of Psychiatry at the Academic Medical Centre in Amsterdam and colleagues analyzed the findings of 50 published studies to confirm that T. gondii infection is associated with mental disorders. The research was published in the journal Acta Psychiatrica Scandinavica.

“In schizophrenia, the evidence of an association with T. gondii is overwhelming,” the authors say in a press release. “These findings may give further clues about how T. gondii infection can possibly [alter] the risk of specific psychiatric disorders.”

“Children can be protected by keeping their cat exclusively indoors and always covering the sandbox when not in use,” Torrey told CBS News in an email. The CDC also recommends changing the cat’s litter box daily, since T. gondii does not become infectious until 1 to 5 days after it is shed in feces. In addition, avoid feeding cats raw or undercooked meat.

This is the first time I’ve had exclusively indoor cats (because we live in a townhouse) and they are neurotic beyond belief.

And if I’m crazy, blame my cats.

Not all meat juice is the same

Posted on April 3, 2015 by Douglas Powell

I’ve always wanted to use the phrase, meat juice, in a peer-reviewed journal article, but researchers from Sweden beat me to it.

Meat juice samples are used in serological assays to monitor infectious diseases within the food chain. However, evidence of inferior sensitivity, presumably due to low levels of antibodies in the meat juice compared to serum, has been presented, and it has been suggested that adjusting the dilution factor of meat juice in proportion to its blood content could improve sensitivity.

In the present study, the agreement between Toxoplasma gondii–specific immunoglobulin G (IgG) levels in meat juice and serum was evaluated, and whether the level of immunoglobulins in meat juice was dependent on its blood content.

Serum and meat juice from diaphragm, heart, tongue, Musculus triceps brachii and M. semitendinosus were collected from 20 pigs experimentally infected with T. gondii. Analysis of total IgG, heme-containing proteins (hematin), and hemoglobin (Hb) revealed significant differences between samples from different muscles, with the highest levels in samples from heart and tongue, and the lowest in samples from leg muscles. Comparison of T. gondii–specific antibody titers in meat juice and serum revealed a strong positive correlation for meat juice from heart (rs=0.87; p<0.001), while it was lower for M. semitendinosus (rs=0.71; p<0.001) and diaphragm (rs=0.54; p=0.02). Meanwhile, the correlation between total IgG and T. gondii titer ratio (meat juice/serum) was highest in diaphragm (rs=0.77; p<0.001) followed by M. semitendinosus (rs=0.64; p=0.005) and heart (rs=0.50; p=0.051). The correlation between Hb and T. gondii titer ratio was only significant for diaphragm (rs=0.65; p=0.008), and for hematin no significant correlation was recorded. In conclusion, the specific IgG titers in meat juice appeared to depend on the total IgG level, but the correlation to blood (Hb or hematin) was poor.

Importantly, large significant differences in total IgG levels as well as in specific antibody titers were recorded, depending on the muscle the meat juice had been extracted from.

“Meat juice” is not a homogeneous serological matrix

Foodborne Pathogens and Disease. April 2015, 12(4): 280-288

Wallander Camilla, Frössling Jenny, Vågsholm Ivar, Burrells Alison, and Lundén Anna

http://online.liebertpub.com/doi/abs/10.1089/fpd.2014.1863#utm_source=ETOC&utm_medium=email&utm_campaign=fpd

Safe because it’s organic? Link found between moose meat and Toxoplasma in unborn baby

Posted on October 13, 2013 by Douglas Powell

A woman in Alaska who ate a medium-rare moose steak at week 26 of her pregnancy gave birth prematurely at 34 weeks because of a toxoplasmosis infection.

According to the Anchorage Daily News, Lauren Hamm’s 34-week prenatal checkup was only supposed to be 10 minutes.

But she left the hospital 96 hours later. Her son, born prematurely, didn’t leave the neonatal intensive care unit for another three weeks.

Doctors said the meat was infected with Toxoplasma gondii, a parasite that can be found in under-cooked game meat. It causes toxoplasmosis, an infection that brings mild flu-like symptoms, like swollen glands, in adults but can be deadly to an unborn child. Hamm’s story was published in the September issue of Alaska Medicine.

Doctors said Hamm had the infection and passed it on to her unborn baby, Bennett. He was born on Dec. 13, 2011, with a heart rate of 200 beats per minute, Hamm said. He had fluid around his organs and lesions on his eyes and brain. Hamm said 45 minutes after Bennett was born, his heart rate was still irregular. Doctors used a defibrillator and shocked his heart back into rhythm.

“I had a prayer in my heart that everything was going to be OK,” she said.

Her doctor, Nelson Isada, a perinatologist at Providence Alaska Medical Center, was the senior author of the article.

Hamm said Isada wondered why Bennett’s heart rate was so irregular, and he ran as many blood tests as he could on her newborn son. According to the article, after Isada found the lesions on Bennett’s eyes, he started to piece together that the baby might have toxoplasmosis.

Isada later tested the moose meat from the family’s freezer and found that it tested positive for Toxoplasma gondii.

According to the article, humans can get Toxoplasma gondii in three ways: by eating under-cooked meat that contains the cysts where the parasite lives, by a mother during gestation, or ingesting the cysts while they are opening in foods, soil, water or a cat’s litter box.

He said women who are pregnant can eat moose meat but they should make sure the meat is cooked all the way through. They should also cook beef, lamb and veal roasts or steaks to 145 degrees and pork, ground meat and wild game to 160 degrees.

Hamm said her husband shot the moose on Joint Base Elmendorf-Richardson, and the family ate the steaks medium-rare, like they always do. She was 26 weeks pregnant.

She said she never considered it unsafe to eat moose meat, because it was organic.

Now, at 22 months old, baby Bennett’s lesions have healed and he is healthy.

Is toxoplasmosis underestimated in the food supply?

Posted on January 7, 2012 by Douglas Powell

When toxoplasma in pork ranked second in last year’s top 10 riskiest combinations of foods and disease-causing microorganisms at $1.2 billion a year, some wondered, what?

Now the Brits have chirped in, saying much more needs to be known about Toxoplasma gondii in the country’s food and especially the impact on pregnant women.

The UK Food Standards Agency’s (FSA) Advisory Committee of the Microbiological Safety of Food (ACMSF) is seeking stakeholder views on its draft report relating to toxoplasma in the food chain (available at http://www.food.gov.uk/multimedia/pdfs/consultation/criskprotoxoplasmafoodchain.pdf).

According to the UK National Health Service (NHS), food sources include undercooked or raw meat, raw cured meat (including Parma ham, salami) and unpasteurised goat’s milk, and the infection can pass between humans from a pregnant woman to an unborn baby.

Although toxoplasmosis usually only causes mild flu-like symptoms in adults, the ACMSF said it can be fatal to babies, and has been linked with associated jaundice, eye infections and seizures.

The FSA’s scientific advisory committee was asked to consider whether current evidence indicates a food safety issue that needs to be addressed, what food sources could present a significant risk and identify further work needed on UK prevalence and foodborne sources of toxoplasmosis.

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