Review, Open Access, Published:

The global serological prevalence of Toxoplasma gondii in felids during the last five decades (1967–2017): a systematic review and meta-analysis

Mahbobeh Montazeri, Tahereh Mikaeili Galeh, Mahmood Moosazadeh, Shahabeddin Sarvi, Samira Dodangeh, Javad Javidnia, Mehdi SharifAhmad Daryani



Felids (domestic and wild cats) are important in the epidemiology of the parasite Toxoplasma gondii because they are the only hosts that can excrete the environmentally resistant oocysts. We conducted a systematic review and meta-analysis to estimate the global prevalence of T. gondii in species of the family Felidae.


We searched seven databases (PubMed, Embase, Google Scholar, ScienceDirect, Scopus, Proquest and Web of Science) for studies reporting seroprevalence of T. gondii in felids from 1967 to 31 December 2017. A total of 217 published papers, containing 223 datasets were eligible for inclusion in the meta-analysis, comprised 59,517 domestic and 2733 wild cats from 1967 to 2017.


The pooled global T. gondii seroprevalence was estimated to be 35% (95% CI: 32–38%) and 59% (95% CI: 56–63%) in domestic cats and wild felids, respectively, using random effects model. The seroprevalence was higher in Australia and Africa where the T. gondii seropositivity in domestic cats was 52% (95% CI: 15–89%) and 51% (95% CI: 20–81%), respectively. The lowest seroprevalence was estimated in Asia 27% (95% CI: 24–30%). The seroprevalence values for T. gondii in wild felids were 74% (95% CI: 62–83%) in Africa, 67% (95% CI: 23–111%) in Asia, 67% (95% CI: 58–75%) in Europe and 66% (95% CI: 41–91%) in South America.


Our study provides the global prevalence of T. gondii in species of the family Felidae and is a source of information to aid public health workers in developing prevention plans.

The following excerpt from the study is important:
Based on formal reports, over one billion people in the world are estimated to be infected with T. gondii[3], which is transmitted mainly by ingestion of food, water, vegetables and fruits contaminated with sporulated oocysts shed from cats or ingesting tissue cysts from raw or undercooked meat [1]….The Centers for Disease Control and Prevention (CDC) reported that toxoplasmosis is the second most common cause of death due to food-borne diseases.
T. gondii has been found in ticks
Here it was found in 64.91% of all examined ticks.
Transmission by ticks has been questioned with mixed results:
Nymphs of Ixodes ricinus are most susceptible to infection with T. gondii and they reported that the role of ticks in transmitting of toxoplasmosis should be considered in further investigations. They also added that Toxoplasma artificially (intracoelomatically) introduced into the organism of I. ricinus females can penetrate and multiply in hypoderma, salivary glands, peritracheal connective tissue and muscular tissue. Moreover, Jagow and Hoffmann (1970) found that Toxoplasma lived in Nymphs and adults of Ornithodoros moubata up till 10 and 2 days, respectively. They also found transmission was unsuccessful either through sucking or with the next stage of the same ticks or through the F1-generation of the ticks infected with Toxoplasma. Whereas, Gidel and Provost (1965) isolated Toxoplasma gondiifrom to the genus Amblyomma parasiting a bovine in Centre African Republic by inoculation into rabbits and guinea pigs and proved pathogenic for mice.
Prudence would err on the side of caution and transmission of T. gondii by ticks should be highly suspected.

For more: T. gondii is responsible for about 1/5 of schizophrenia cases.

And lastly, I’ll never forget this information on how parasites affect human behavior by Dr. Klinghardt, which I found here:

  • Parasite patients often express the psyche of the parasites – sticky, clingy, impossible to tolerate – but a wonderful human being is behind all of that.

  • We are all a composite of many personalities. Chronic infections outnumber our own cells by 10:1. We are 90% “other” and 10% “us”. Our consciousness is a composite of 90% microbes and 10% us.

  • Our thinking, feeling, creativity, and expression are 90% from the microbes within us. Patients often think, crave, and behave as if they are the parasite.

  • Our thinking is shaded by the microbes thinking through us. The food choices, behavioral choices, and who we like is the thinking of the microbes within us expressing themselves.

  • Patients will reject all treatments that affect the issue that requires treating.

  • Patients will not guide themselves to health when the microbes have taken over.

With this information in mind, it’s quite clear how Lyme/MSIDS is such a complex disease as many are dealing not only with Lyme but other coinfections including parasites which are either directly transmitted by a tick or activated due to a trigger and a dysfunctional immune system.