The value of pets to children
Ernby, director of allergy and immune system research at the Medical College of the University of Georgia, confirmed after seven years' research on 474 full-term healthy infants that if newborns under 1 live with two or more cats and dogs at home, their chances of developing allergies and asthma will be greatly reduced when they grow up. What is more striking is that the protective effect can not only reduce animal allergies, but also be extended to resist common allergens, such as grass, pollen and moths. /kloc-Children with two or more pets under 0/year old have 77% lower allergic rate in skin puncture test and 67% lower allergic rate in blood test than children without pets.
Another study conducted by the University of Bonn in Germany proves that pets are more valuable to children than their closest friends. Whether from the child's point of view or from the mother's point of view, pets have the function of stabilizing emotions and treating mental trauma. They found that children with pets are easier to integrate into society and less aggressive than children without pets, while children without pets are more inclined to take extreme actions-more stubborn, more excited and more prone to violent behavior.
In recent years, there are more and more cats and dogs in domestic families, and many newspapers warn the public that cats and dogs can cause toxoplasmosis and lead to terrible fetal malformation. Although this is necessary, it is a pity that many articles are inaccurate, exaggerated and grandstanding, causing unwarranted panic among the public and causing many small animals to be abandoned. This paper gives the answers to several questions that pet owners often ask.
1. What is toxoplasmosis?
Toxoplasma gondii is an infection caused by parasitic Toxoplasma gondii. Toxoplasma infection is very common all over the world. About 16~40% of adults in the United States and Britain have been infected, and some surveys have reached 70%, while adults in continental Europe and Latin America have been infected, with 50~80% as high as 90% in France. From 1985 to 90, most of the surveys in 23 provinces, municipalities and autonomous regions in China are below 10%, which is obviously lower than that in foreign countries.
Most normal people infected with Toxoplasma gondii have no symptoms, or the symptoms are very mild. I wonder when they were infected. Only a few people have fever, swollen lymph nodes, headache, muscle joint pain, abdominal pain and other symptoms when they are infected for the first time. After a few days or weeks, the human body produces immunity and the symptoms are mild. Only formed cysts exist in the body for months, years or longer, and usually heal themselves. But patients with severe immunodeficiency, such as AIDS patients, will have serious consequences if they are infected. The infection of pregnant women can be transmitted to the fetus and may have serious consequences.
2. How is Toxoplasma transmitted?
The first is to eat undercooked meat, especially pigs and sheep. Almost all mammals and birds, such as rats, pigs, sheep, cows, rabbits, chickens, ducks and geese, can be infected with Toxoplasma gondii, and the infection rate is very high. The source of human infection mainly comes from the meat of these animals. If the temperature of the meat is not enough and the time is too short, Toxoplasma gondii is not killed and there is a risk of infection. Contamination of raw meat or chopping boards can also be contagious. Contaminated sheep and milk may also be contagious. The low infection rate of Toxoplasma gondii in China may be related to the cooked meat habits in China.
Dogs can also be infected with Toxoplasma gondii, but their feces and excreta are not contagious, and they will not be infected if they don't eat dog meat. Some people say that "dogs are closely related to people and are one of the important sources of infection for human beings", and blame the children with "mental retardation, congenital heart disease or extra finger" on keeping dogs at home. These are groundless.
Infected cat droppings are an important source of infection. Cats and cats are the ultimate hosts of Toxoplasma gondii, and fertilized eggs are excreted from infected cat feces, which generally lasts 1 week for 20 days, and the longer ones are rare; This period is infectious. Surveys around the world show that about 1% of cat feces contain Toxoplasma zygote. The zygote in cat feces must develop in the outside world for 2~5 days before it becomes contagious, so it is very important when to deal with cat feces. A fertilized egg can survive in water and moist soil for several months or longer. Therefore, food, drinking water and even dust contaminated by cat feces will be contagious if eaten by people. In areas where meat is completely cooked, cats are an important source of infection for people. However, many other animals can also spread as intermediate hosts. For example, there are few cats in many pastures and many cattle and sheep are infected; Moreover, there are still some islands in the world without cats, and the infection rate of residents on the islands is still very high. Therefore, there is an important book "Human Parasitology" in China, which says: Because of the high infection rate of domestic animals as intermediate hosts, the pollution of cat feces is not as important as eating immature meat from the source of human infection.
Toxoplasma gondii infection in pregnant women can be transmitted to the fetus, causing congenital infection, which may have serious consequences, so it is very important. However, only pregnant women who have not been infected with Toxoplasma gondii before pregnancy can infect the fetus for the first time during pregnancy. If pregnant women have been infected with Toxoplasma gondii before pregnancy, there is no longer the risk of infection.
3. What harm does congenital Toxoplasma infection do to the fetus?
If congenital infection occurs in the first three months of pregnancy, about 40% of the fetus may be seriously damaged, leading to miscarriage, stillbirth or neonatal diseases, or there are diseases or abnormalities in the eyes, brain or liver after birth, such as choroiditis, cataract, cerebral calcification, hydrocephalus, microcephaly, mental retardation, jaundice, hepatosplenomegaly and so on. Infection in the third trimester is less than 3% serious.
In 1996, a study on the influence of Toxoplasma gondii on fetus in Helsinki University Hospital, Finland, found that among 16733 pregnant women who received serum antibody examination, only 42 were primary infected, and 36 of them received spiramycin treatment. After long-term follow-up, 4 children developed congenital toxoplasmosis, 2 had severe nervous system diseases and 2 had no clinical symptoms. Children born to other pregnant women with primary infection are no different from other pregnant women in growth, development and intelligence.
4. Do pregnant women need routine examination of Toxoplasma antibodies?
Although France, Austria and other countries stipulate that pregnant women should routinely detect Toxoplasma antibodies, the practice is to check serum antibodies in the early pregnancy. If it is negative (that is, not infected), tell pregnant women to pay attention to prevent infection and check it regularly; Once the acute infection of pregnant women is found, it is treated with spiramycin, and the fetus is examined by amniocentesis and ultrasound. If fetal infection is proved, pregnant women are treated with sulfadiazine and pyrimethamine; If the fetus is found to have obvious symptoms, parents can consider terminating the pregnancy. But whether this method is worth adopting is still controversial. Because the probability of pregnancy infection and fetal infection is very small, British and American studies have concluded that this screening is not worth routine.
Screening pregnant women for infection is a very serious public health problem. It is generally believed that it should be based on local epidemiological research. First of all, the inspection should have clear peony and treatment principles, the screening method should have high accuracy, and the systematic inspection and treatment should be sustainable and acceptable to the public. Cost-benefit analysis shows that it does have high benefits.
At present, many hospitals in China have generally carried out Toxoplasma antibody examination for pregnant women. Some hospitals are not standardized in examination and treatment, and the examination belongs to examination, and the result doesn't matter, so they don't do treatment. More than once, someone asked me the meaning of the test results: what if it is positive? Need treatment or termination of pregnancy? Some results are contradictory. Is one hospital positive, or is another hospital negative? Why? Therefore, the quality of reagents and tests must be high, the screening methods must be standardized, and clinicians must be familiar with the significance and judgment of serological test results. The false positive and false negative results caused by poor experimental quality not only waste patients' money, but also cause anxiety of patients and their families, bring huge mental burden and even cause irreparable losses.
Compared with foreign countries, pregnant women in China are less likely to be infected. Therefore, China should conduct evaluation and research in qualified hospitals before making relevant policies. Before there is a clear policy, it should not be blindly and universally implemented.
5. How to prevent Toxoplasma infection?
First, pay attention to food hygiene. Meat should be cooked thoroughly to avoid contamination of cooked food with raw meat.
Second, cats should be kept at home and fed with cooked food or finished cat food to prevent them from preying outside. Because cats are infected by eating infected mice or birds, or by eating food contaminated with cat feces.
Third, we should pay attention to daily hygiene, remove cat feces every day, and wash our hands carefully after touching animal feces.
Fourth, pregnant women should avoid contact with cats and their feces during pregnancy unless their serum tests prove that they are infected with Toxoplasma gondii.
Fifthly, there are many simple and effective drug treatments for Toxoplasma gondii infection, such as sulfadiazine plus pyrimethamine and spiramycin. Treatment must be carried out according to the doctor's advice. Timely treatment of pregnant women's infection can reduce the chance of fetal infection.