Toxoplasma gondii and pregnancy

Toxoplasma gondii, an obligatory intracellular parasite, instigates worldwide toxoplasmosis in humans and warm-blooded creatures. Prevalence differs regionally. Notable risk factors encompass food type, cooking methods, water treatment, and cat interaction, particularly for immunocompromised individuals. T. gondii's lifecycle encompasses final hosts (mostly cats) and intermediate hosts (humans, dogs, etc.). Infection in intermediate hosts stems from consuming undercooked meat or contaminated food with oocytes expelled by cats. This understanding is pivotal in managing the spread and impact of this parasite-linked disease.

Toxoplasma gondii, an obligate intracellular protozoan, completes its lifecycle within cats, acting as definitive hosts. Infection occurs through consumption of rodents carrying bradyzoites. Cats shed oocysts for about 1-2 weeks post-infection, with sporulation taking over 24 hours. An IgM titer ≥1:64 indicates recent infection, posing oocyst shedding risk. Owners with prior exposure might exhibit immunity, protecting against infection during pregnancy.

For T. gondii, a coccidian protozoon, cats serve as sexual phase hosts, while warm-blooded vertebrates, including humans, act as intermediate hosts. Transmission routes include meat-borne bradyzoites and cat feces-borne oocysts. Cats shed oocysts for 7-21 days, potentially leading to severe disease. Sporozoites from oocysts infiltrate and replicate in organs, muscles, and nervous systems.

Toxoplasmosis epidemiology unveils widespread T. gondii exposure in cat populations, with up to 74% seroprevalence globally. Dogs also exhibit high exposure (30%-64% seroprevalence). Often asymptomatic, infections become chronic. Cats contract the infection through rodents, driven by altered rodent behavior due to T. gondii. This zoonotic infection poses risks for humans, causing diverse serious conditions.

Preventing T. gondii involves restricting hunting and feeding cats and dogs undercooked meats. Cockroach control is crucial, and daily litterbox cleaning minimizes oocyst transmission.

In immunocompetent individuals, primary T. gondii infection induces fever, malaise, and lymphadenopathy. Maternal infection during gestation can result in stillbirth, CNS, and ocular diseases. Around 10% of AIDS patients develop toxoplasmic encephalitis from bradyzoite reactivation. The correlation between T. gondii and behavioral/mental issues varies. Tissue persistence underscores the significance of avoidance. Humans contract toxoplasmosis through oocysts, tissue cysts, or transplacentally. Prevention involves evading undercooked meats and sporulated oocysts. 

Toxoplasmosis is frequently asymptomatic in humans, but it can be severe in congenital or postnatal infections. Most critical during the first trimester, congenital cases can lead to neurological and ocular issues. Generally latent, toxoplasmosis might manifest with non-specific clinical signs.

Severe effects impact immunocompromised individuals and pregnant women. Neonate cats, geriatric, and immunocompromised animals experience chronic illness and clinical symptoms.

Serological tests (direct agglutination, latex agglutination, ELISA) detect antibodies. PCR offers better sensitivity and specificity. A study identified T. gondii DNA in milk samples from goats, sheep, and cows in select countries.

Risk factors for T. gondii include poor education, with odds decreasing by 83% and 98% for low- and high-educated women, respectively, compared to illiterate women.

A higher rate of T. gondii infection occurred among employed pregnant women, potentially linked to specific occupations and associated risks. Hygiene practices revealed raw meat consumption elevated infection risk compared to cooked meat. Drinking raw milk posed a higher risk than pasteurized milk. 

Contact with cats, the oocyst-spreading hosts, saw interactions with stray and pet cats linked to infection. No direct connection between ownership and infection was observed. Handwashing after cat contact reduced infection risks due to fecal-oral transmission. The high prevalence attributed to rural residence, cat contact, and poor hygiene compliance among participants.

Poor education, occupation, raw milk consumption, contact with cats without appropriate hygienic practices, and undercooked meat eating linked to T. gondii infections. 

Urgent handwashing awareness campaigns are crucial for public health. Cat owners, especially pregnant women, should be aware of T. gondii infection risks and adopt appropriate hygienic practices.

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REFERENCES:

• Hassanen, EAA. Interplay between cross sectional analysis of risk factors associated with Toxoplasma gondii infection in pregnant woman and their domestic cats. Frontiers in Veterinary Science. 2023. 

• Bruyette, DS. Clinical Small Animal Internal Medicine. Wiley Blackwell. 2020. 

• Sykes, JE. Greene’s Infectious Diseases of the Dog and Cat. 5th ed. Elsevier. 2023