This meme dates from 2010. Image Source: Know Your Meme.
Today's post concerns how cats influence human health, based on the article: Influence of latent Toxoplasma infection on human personality, physiology and morphology: pros and cons of the Toxoplasma–human model in studying the manipulation hypothesis. That article concerns the often asymptomatic or latent disease, toxoplasmosis, caused by an intercellular parasite which is passed through cats to humans and is related to human depression, autism, cerebral calcification, sex addiction, and schizophrenia. It is a disease that affects rodents and makes them lose all fear of cats; this has allowed the parasitic protozoan to return to feline systems, where it can complete its life cycle. The parasite also affects the rodent brain's sexual impulses and reward centres.
Toxoplasma gondii parasitic protozoa. Image Source: Ke Hu and John Murray via Business Insider.
Scientists believe that toxoplasmosis infection similarly makes humans attracted to cats. The disease affects an enormous number of people, which may incidentally ensure the survival of the domestic cat, while also safeguarding the protozoan. Wiki:
Perhaps those Walking Dead zombie stories are telling you the truth about a reality you suspect, but cannot see. If you think everyone around you is infected by some mysterious bug that makes them crazy, you may not be paranoid. You may be right. From Florence Robert-Gangneux and Marie-Laure Dardé in American Society for Microbiology (2012):"Up to half of the world's population are infected by toxoplasmosis but have no symptoms. In the United States about 23% are affected and in some areas of the world this is up to 95%. About 200,000 cases of congenital toxoplasmosis occur a year. Charles Nicolle and Louis Manceaux first described the organism in 1908. In 1941 transmission during pregnancy from a mother to a child was confirmed."
Approximate rates of infection by country below are almost all based on tests of pregnant women. Some studies only focus on particular regions, and the numbers change from year to year. Follow the links for years and details; not all countries conduct studies or keep statistics. Note that these statistics tend to show infection passed from mother to child in the womb. They do not include post-natal infection, in which people are infected directly by handling cats or eating raw or rare meat:"Low seroprevalences (10 to 30%) have been observed in North America, in South East Asia, in Northern Europe, and in Sahelian countries of Africa. Moderate prevalences (30 to 50%) have been found in countries of Central and Southern Europe, and high prevalences have been found Latin America and in tropical African countries."
- Argentina: sources for Buenos Aires 45.6%-57.2% infected
- Australia: 28% infected; 23% found infected in pregnant women from Melbourne
- Bahrain: 22.3% tested positive, from pregnant women in Manama only
- Belgium: 48.7% infected
- Brazil: 66.9% infected; other sources range 55.6%-77.8%, depending on region
- Canada: unknown; extrapolated estimate 14%-22% infected
- Chile: 40%-90% of the population, depending on region
- China: Changchun only, 10.6% infected among pregnant women
- Colombia: 43.1%-66.7%, different sources, depending on region
- Costa Rica: approximately 55%, increases in rural areas and with poverty
- Croatia: 38.1% infected
- Cuba: different studies from Havana areas, 44%-66.3%
- Czech Republic: 30%-40% infected; in Prague, 19.8% infected
- Denmark: statistics for Copenhagen, 27.8% infected
- Egypt: measured in women only, 46.5% in urban areas, 57.6% in rural areas
- France: 45% infected
- Germany: Western Pomeranian statistics only, 63.2% infected
- Greece: depending on different studies and different regions, 20%-36.4% infected
- Grenada: 57% infected, nationwide estimate
- India: 11.6%-45%, depending on class and region
- Iran: 29.4%-63.9%, depending on class and region
- Iraq: 49.2% infected, statistics for pregnant women tested in Basra
- Italy: 17.5%-34.4%, a range of averages, from different studies and different regions
- Ivory Coast: 60% infected among pregnant women from Abidjan
- Jordan: 47.1% infected in Amman
- Kuwait: 45.7% infected among pregnant women
- Malaysia: 49% infected among pregnant women from Kuala Lumpur
- Mexico: extrapolated estimate 22% infected; another source found 6.1% of pregnant women infected in Durango
- Morocco: Rabat statistics only, among pregnant women, 50.6% infected
- Netherlands: 35.2% nationwide
- New Zealand: statistics for pregnant women from Auckland, 35.4% infected
- Poland: 35.8%-43.7% infected, based on pregnant women only in three cities, Warsaw, Lodz, Poznan
- Romania: 57.6% infected in women of child-bearing age, Timisoara only
- Serbia: 33% infected nationwide
- Singapore: 17.2% infected among pregnant women
- Slovakia: 22.1% among pregnant women, Bratislava data only
- Slovenia: 34% infected nationwide
- South Korea: 4.3% infected; other sources range 0.8%-3.7% infected in Daejeon and Suwon
- Spain: 18.8%-43.8% infected, averages from certain regions only
- Sudan: Khartoum and Omdurman only, pregnant women tested, 34.1% infected
- Sweden: 18% infected from Stockholm and Skane only
- Switzerland: 8.2%-35% infected, based on data from Lausanne, Geneva, Basel only
- Thailand: 5.3%-21.5% infected among pregnant women from different regions
- Turkey: 30.1%-60.4% average infected among pregnant women, from different classes and regions, impacted by regional culinary traditions (consumption of raw meat)
- United Kingdom: 31% infected, 20 million people in 2012, with 80% of these asymptomatic; East Kent statistics for pregnant women showed 9.1% infected
- USA: 15%-22.5% of the population, depending on demographic, 60 million+ infected; another source states 11% nationwide, with 7.76% for US-born and 28.1% for foreign born
- Venezuela: 38% infected among pregnant women from Lara State
- Vietnam: from Nha Trang only, 11.2% of pregnant women infected
Image Source: Twitter.