Parasitic disease

Introduction to parasitic diseases Parasitic diseases (parasitic diseases), diseases caused by parasites invading the human body. Pathological changes and clinical manifestations vary depending on the species and parasitic parts. This type of disease is widely distributed and can be seen all over the world. However, it is more common in areas with poor poverty and poor sanitation, and there are more tropical and subtropical regions. Therefore, the narrow sense of tropical disease refers to parasitic diseases. The developing countries in Africa and Asia are more ill, and the infected people are mainly exposed to working people with more epidemics and children with lower immunity. Drug treatment is mainly to eliminate parasites, and the most effective deworming drugs are used according to the species. According to the type of insects, the strength of the constitution, the severity of the symptoms, etc., the appropriate prescriptions are selected and compatible. If there is accumulation, it can be used as a drug for elimination; the spleen and stomach are weak, and the spleen and stomach can be supplemented; for the weak, the patient should first make up the attack, or attack and supplement the spine; Lord, and after the pain is relieved, deworming again. basic knowledge The proportion of illness: 3% Susceptible people: no special people Mode of infection: contact transmission, digestive tract transmission, respiratory tract transmission Complications: acute appendicitis peritonitis

Cause of parasitic diseases

Parasite number and virulence (50%):

The more invasive worms and the stronger the virulence, the more chances of morbidity and the heavier conditions. Pathological changes mainly include damage caused by mechanical damage of host tissues to the host tissues, tissue necrosis caused by toxins or enzymes secreted by the worms, and infiltration of eosinophils and other inflammatory cells caused by host reactions, and even formation of acidophilus. A granulocyte abscess and an eosinophilic granuloma that develops on larvae or eggs.

Host immunity (50%):

The stronger the host's resistance, the less chance of morbidity after infection, even if the disease is onset. The process of parasitic disease is the result of the struggle between the host and the worm.

Source of infection: including insects (sacs), storage hosts and recurrent hosts. For example, patients with amoeba and black fever can be used as sources of infection; dogs can be used as storage hosts for kala-azar; wild boars can be used as a relay host for paragonimiasis to spread diseases.

The route of transmission can be divided into: 1 oral infection. If you eat water or food contaminated with infectious aphid eggs or amoeba, you can get tsutsugamushi or amebiasis. 2 spread by blood-sucking vector insects. If the Anopheles mosquito infected with Plasmodium is bitten, it can develop malaria. 3 infection through the skin. For example, the filamentous mites of hookworm can be directly infiltrated into the host skin to infect them. 4 through the placenta infection. Such as congenital malaria, congenital toxoplasmosis and so on. 5 infection through the respiratory tract. For example, primary amoebic meningoencephalitis is infected by nasal mucosa. 6 other ways. Such as blood transfusion can be infected with malaria parasites.

In addition, the spread of parasitic diseases requires certain conditions to be prevalent, such as: 1 the existence of vector insects or intermediate hosts. For example, Plasmodium, Filaria, etc. need to be propagated after the specific insects (Anopheles, Culex) develop and multiply. Some parasites need to develop in two or more intermediate hosts before they can infect humans. For example, the Chinese branch squid needs to develop into a scorpionfish in the freshwater snail to infect some freshwater fish, and develop into a sac in the fish. Infecting humans; therefore, the epidemic area of this parasitic disease is affected by the distribution of vector insects and intermediate hosts. 2 suitable developmental environment. For example, aphid eggs need to be in the soil and develop into infectious eggs under suitable temperature, humidity and aerobic conditions. 3 bad hygiene and eating habits. In some areas, there are raw habits (such as eating fish porridge, drunken crabs) and infection with Chinese branch schistosomiasis and paragonimiasis.

Susceptible population: Non-immune people or children with low immunity are susceptible to local epidemics. For example, when a large number of immigrants move from non-endemic areas to malaria endemic areas, malaria outbreaks often occur.

Some socio-economic factors such as economy, living conditions, customs and habits can affect a certain popular link and affect the epidemic. Therefore, when there are the above three links, the epidemic of parasitic diseases can occur, and if the link is cut off, the epidemic of parasitic diseases can be controlled.

The damage of the parasite to the host is mainly manifested in three aspects:

1. Plunder nutrition: The nutrients required for the growth, development and reproduction of parasites in the host are all from the host. The more parasitic insects, the more serious the plundering of the host nutrients. Some intestinal parasites not only directly absorb the nutrients of the host, but also prevent the host from absorbing nutrients, which makes the host more prone to malnutrition.

2. Mechanical damage: The migration and settlement of parasites in the host can cause damage or destruction of the host tissue. For example, B. vannamei trematode is attached to the intestinal wall by strong suction cups, which can cause damage to the intestinal wall; migration of the vaginal worms in the host can cause damage to multiple organs such as liver and lung; The echinococcosis formed in the host can destroy the parasitic organs and can also compress adjacent tissues, causing damage to multiple organs or tissues; the mites entangled in the intestinal tract can block the intestinal lumen and cause intestinal obstruction. Some facultative or accidental parasites invade the human body or cause ectopic parasitis. The migration or settlement of the worm in the human body causes the tissue damage of the host to be more serious than the obligate parasite. If the parasitic part is an important organ such as the brain, heart, or eye, the prognosis is quite serious, which can cause a serious decline in the quality of life, and even fatal.

3. Toxicity and immune damage: parasite excretion, secretion, worm body, disintegration of egg death, worm's molting liquid may cause tissue damage or immunopathological reaction. Such as Parasitoid sinensis parasitic in the bile duct system, its secretions, metabolites can cause bile duct epithelial hyperplasia, nearby liver parenchymal atrophy, bile duct local expansion, thickening of the wall, further development can lead to epithelioid hyperplasia, schistosomiasis antigen and The binding of the host antibody to the antigen-antibody complex can cause damage to the glomerular basement membrane; for example, the adult hookworm can secrete anti-coagulant, and the wound of the damaged intestinal tissue is bleeding.

Parasitic disease prevention

Comprehensive measures should be taken to adapt to local conditions and to adopt different effective methods for different diseases.

1 Large area treatment of patients, eliminating storage hosts to eliminate the source of infection.

2 cut off the route of transmission, such as eliminating vector insects or intermediate hosts.

3 Strengthen health education to change bad hygiene and eating habits, not to drink raw water, not to eat unfamiliar food.

4 Strengthen the population's immunity and personal protection, such as the use of mosquito nets to avoid mosquitoes. Some parasite vaccines such as the Plasmodium vaccine have been studied, but there is still a considerable distance from the practical stage.

Parasitic complications Complications acute appendicitis peritonitis

Iris parasitic disease: secondary infection produces acute appendicitis, the inflammatory phase. Following the increase in pressure in the appendix, ischemia, necrosis, perforation, and aphids on the appendix wall can be drilled into the abdominal cavity, causing severe suppurative peritonitis.

Symptoms of Parasitic Diseases Common Symptoms Fecal Nematode Disease Umbilical Week Pain Indigestion Facial Pale Anal Night Itchy Abdominal Pain Weight Loss Nail Small Fine Granules

Symptoms of parasitic diseases:

1. Indigestion: paroxysmal umbilical pain, indigestion, weight loss, slow development, memory loss, may have ascariasis, whipworm disease.

2. Itching: It often feels itchy around the anus and the perineum. It is nighttime, sleepless, dreamy, and may have tsutsugamushi disease.

3. Abdominal pain, diarrhea: abdominal pain, diarrhea up to 5 times a day, with a stench smell, and dark red mucus bloody stool, may have amebiasis; abdominal pain, diarrhea and raw food mustard, water chestnut, sputum Those who are in the history of aquatic plants may have ginger worm disease.

4. Anemia: pale and yellow, dizzy, weak, and occupational farmers, may suffer from hookworm disease.

6. Abortion: pregnant women with unexplained miscarriage, premature birth, stillbirth, and love to raise cats, pregnant women who have fever, weakness, muscle soreness, may suffer from toxoplasmosis.

7. chills, fever: hemoglobin reduction, past malaria endemic areas, intermittent chills, fever, sometimes body temperature up to 39 ° C, for more than a week, may have malaria.

8. Urinary pain, frequent urination: women have genital itching, increased vaginal discharge, odor, and may have dysuria, frequent urination, etc., may be infected with vaginal trichomoniasis.

Anyone with the above symptoms should go to the hospital for further examination.

Parasitic examination

Pathogen examination: look for worms in body fluids or secretions, such as fecal smear or agglomeration to check intestinal protozoa trophozoites, cysts or worm eggs, peripheral blood smears to find malaria parasites, etc., parasites in host tissues Can be diagnosed by biopsy or puncture.

Immunological examination: Currently commonly used methods are intradermal test and serum immunoassay.

Intradermal test: intradermal test can be divided into immediate response and delayed response, and the former is the former, which can be used as a clinical screening or epidemiological investigation.

Serum immunology test: Indirect red blood cell agglutination test (IHA), indirect fluorescent antibody technology (IFT) and enzyme-linked immunosorbent assay (ELISA), the former has higher sensitivity, and the sensitivity and specificity of the latter two are higher. These methods are mainly used to detect specific antibodies of the host, and methods for detecting circulating antigens or excreting antigens have also been established for early diagnosis and efficacy evaluation.

Other tests: such as ultrasound examination.

Diagnosis and identification of parasitic diseases

diagnosis

1 pathogenic diagnosis: find the body in the body fluid or secretions, such as fecal smear or agglomeration to check the intestinal protozoa trophozoites, cysts or worm eggs, peripheral blood smear to find malaria parasites, parasites in the host tissue It can be diagnosed by biopsy or puncture.

2 immunological diagnosis: currently commonly used methods are intradermal test and serum immunoassay. The intradermal test can be divided into immediate response and delayed response, and the former is the former, which can be used as a clinical screening or epidemiological investigation. The Leishman's skin test is the latter, and only a positive reaction occurs during the recovery period of the disease. It can only be used as an epidemiological survey to understand the prevalence of the disease in the past. At present, the commonly used serum immunological tests include indirect red blood cell agglutination test (IHA), indirect fluorescent antibody technology (IFT) and enzyme-linked immunosorbent assay (ELISA). The sensitivity of the former is high, and the sensitivity and specificity of the latter two are high. These methods are mainly used to detect specific antibodies of the host, and methods for detecting circulating antigens or excreting antigens have also been established for early diagnosis and efficacy evaluation.

3 History of epidemiology: from epidemic areas, such as schistosomiasis with a history of exposure to water, and paragonimiasis with a history of unfamiliar stone crabs.

4 clinical manifestations: each has its clinical features, peripheral blood eosinophils tend to increase.

5 other examinations, such as ultrasound examination, CT examination, etc.

Differential diagnosis

It is differentiated from tsutsugamushi disease and tsutsugamushi disease.

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