What Are the Different Causes of Macular Rashes?

Biological harmful factors are a class of biological factors that have harmful effects on the health of the occupational population in the production materials and the production environment, including pathogenic microorganisms, parasites, animals and plants, insects, and the biologically active substances they produce. Biological harmful factors can cause a variety of hazards, but mainly harm the health of the working population.

Pathogenic microorganisms, parasites, animals and plants, insects, etc., which are harmful to the health of the occupational population, and the biologically active substances produced in the production materials and the production environment are collectively referred to as biologically harmful factors. For example, Bacillus anthracis, Brucella, tick-borne encephalitis virus, Mycoplasma, Chlamydia, Leptospira, and pathogenic microorganisms such as fungi or fungal spores that grow on moldy bagasse and grass dust, attached to animal skin And its toxic products; irritating, toxic or allergic bioactive substances produced by certain animals and plants, such as scales, powders, hair, feces, toxic secretions, enzymes or proteins and pollen, etc .; There are many types of pupae, silk, silkworm pupae, cocoons, mulberry caterpillars, pine caterpillars, etc.

Diseases caused by biologically harmful factors are called biohazards. Biological hazards fall into five categories: occupational bacterial infectious diseases, such as anthrax and brucellosis. Occupational virus infectious diseases, including forest encephalitis, foot-and-mouth disease, and rabies. Occupational fungal diseases, such as actinomycosis and dermatomycosis. Occupational Borrelia infectious diseases, such as Leptospirosis. Occupational parasitic diseases, such as cysticercosis, tsutsugamushi, and hookworm are common. Such occupational infectious diseases often co-exist with non-occupational infectious diseases and are regional in nature.

In addition to the harmful effects of biological harmful factors on the health of occupational populations, in addition to causing occupational diseases such as anthrax, brucellosis, and forest encephalitis, due to different pathogens, it can also cause plague, foot and mouth disease, milker's nodules, herder rabies, hook Diseases such as treponemasis. Especially in recent years, new infectious diseases such as infectious atypical pneumonia, human infection with highly pathogenic avian influenza, and swine streptococcus disease have greatly affected the health of occupational populations in the related industries of poultry and livestock.

Occupational diseases caused by biological harmful factors include: anthrax, brucellosis, and forest encephalitis. The pathogenic microorganisms are anthracnose, brucella, and forest encephalitis virus.

Biological anthrax

Anthrax is a zoonotic acute infectious disease caused by Bacillus anthracis. It mainly occurs in herbivores. Humans become infected after coming into contact with sick animals and their products. Anthrax is one of the legal occupational diseases in China.

1. Etiology and pathogenesis

Bacillus anthracis is a gram-positive aerobic bacillus. Anthracis anthracis has capsules in the host or on serum-containing media. Capsule has anti-phagocytosis and strong pathogenicity. Bacillus anthracis does not form spores in living animals. In vitro, spores can form when exposed to sufficient oxygen and the appropriate temperature. Strong spore tolerance. Bacterial propagules are weak and very sensitive to heat and common disinfectants.

The main pathogenic substances of Bacillus anthracis are capsules and anthrax toxins. Capsules can resist the phagocytosis of phagocytic cells, which is conducive to the survival, reproduction and spread of the bacteria in the body. Anthrax toxin mainly damages the capillary endothelium, enhances the permeability of the blood vessel wall, reduces the effective blood volume and the volume of microcirculation perfusion, makes the blood in a hypercoagulable state, and easily leads to diffuse intravascular coagulation and septic shock.

2.Epidemiology

Anthrax is globally distributed. It occurs throughout the year in China, often spreading, with occasional local epidemics, and the epidemic peaks from July to September. In recent years, the annual number of cases in China has been around 300. The western region has a higher incidence, which is more common in pastoral areas. Drought or rain, floods and floods are all factors that promote anthrax outbreaks. Agricultural anthrax is often caused by direct contact with infected animals. It is more common among farmers, herders, fur processing, animal slaughter, and veterinary workers. Industrial anthrax mainly involves those who come into contact with infected animal products (animal skin, fabric, hair).

(1) The main sources of infection are diseased herbivores, such as cattle, horses, sheep, and camels. Their skin, hair, meat, and bone meal can carry Bacillus anthracis. All human cases originate from animal infections, and no human-to-human transmission has been reported.

(2) Transmission routes Anthrax spores and their bacteria can be transmitted through the skin, respiratory tract and digestive tract. Humans can cause skin anthrax directly or indirectly through contact with diseased animals or their excrement and infected animal skin, meat, bone meal, etc .; ingestion of diseased meat and dairy products can cause intestinal anthrax; inhalation of spore-bearing droplets And aerosols can cause anthrax in the lungs.

(3) Vulnerable populations are generally susceptible. Farmers and herdsmen, animal breeders, hunters, slaughterhouses and fur processors, veterinarians and animal quarantine personnel are at high risk. Human immunity generally does not exceed one year after suffering from anthrax.

3, can be divided into the following 5 disease types.

(1) Skin anthrax is the most common, accounting for more than 95%. The incubation period is generally 1 to 5 days, as short as 12 hours and as long as 12 days. Lesions are more common on the exposed areas of the face, neck, shoulders, hands, and feet. Pimples or spotted skin appear at first. Blisters formed the next day, and the surrounding tissues became edema. On the 3rd to 4th days, the center of the lesion was hemorrhagic and necrotic and slightly subsided, and there were clusters of small blisters around it. The range of edema is constantly expanding. On the 5th to 7th days, the necrotic area was ruptured to form a superficial ulcer, and bloody secretions formed charcoal scorch. Within 1 to 2 weeks after the edema subsided, the black pheasant spontaneously fell off and gradually healed to form a scar. Body temperature increased 1 to 2 days after the onset of the disease, accompanied by headache, local lymphadenopathy, and joint pain.

(2) Intestinal anthrax is extremely rare. Acute onset, fever, bloating, severe abdominal pain, diarrhea, usually bloody stools or bloody stools. There is obvious tenderness in the abdomen, rebound pain, and even abdominal muscle tension. May have nausea, vomiting and septicemia and die within a few days.

(3) Pulmonary anthrax is rare. Most are primary and can also be secondary to skin anthrax. Flu-like manifestations at the beginning of the illness. After 2 to 4 days, high fever appeared. Severe breathing difficulties may include chest pain and cough, hemoptysis, and common pleural effusion. Shock can occur and die within 24 hours. Sepsis and meningitis often occur.

(4) Meningitis type anthrax is mostly secondary to lung, intestine, and severe skin anthrax, and may also occur directly. The clinical manifestations are severe headache, vomiting, and Xiang Qiang, followed by delirium, coma, and respiratory failure. Most of the cerebrospinal fluid is bloody, and Gram-positive E. coli is easy to find.

(5) Septic anthrax is secondary to lung, intestine, and severe skin anthrax, and may also occur directly. In addition to the exacerbation of the primary local manifestations, there were further severe symptoms of systemic poisoning, high fever, chills, septic shock and diffuse intravascular coagulation, and rapid respiratory and circulatory failure.

4.Diagnosis

Refer to China's "Anthrax Diagnostic Standard WS283-2008". Comprehensive diagnosis of epidemiological history, clinical symptoms and signs, laboratory tests, etc., and the patient has a positive result of bacteriological or serological diagnosis. According to the diagnostic standards for occupational infectious diseases in China (GBZ227-2010), confirmed cases with a history of occupational exposure can be diagnosed as occupational anthrax ^[1] .

5. Prevention principles

(1) Strictly isolate patients during treatment, diagnose as soon as possible, and treat as soon as possible to kill the anthrax bacillus in the body. Adopt comprehensive measures combining symptomatic treatment and pathogenic treatment.

(2) Prevention

Strictly manage the source of infection: from the time of suspected diagnosis, anthrax patients are isolated and treated at the diagnosis place or at home to avoid long-distance transfer of patients. The key to controlling anthrax in humans is to control anthrax in animals. Suspected animal cases must be quarantined; diseased animals are generally not treated and should be strictly destroyed; dead animals must be burned or buried in a large amount of quicklime. Do not peel or cook.

Cut off the transmission route: the secretions and excreta can be disinfected with chlorine-containing disinfectant; the infected fur can be disinfected with formaldehyde; clothing or textiles can be disinfected with boiling, high-pressure steam or ethylene oxide; Disinfection; terminal disinfection can be treated with formaldehyde fumigation. Animal product processing plants should improve industrial hygiene, strengthen labor protection, and wear work clothes, masks and gloves when working. It is forbidden to trade animals and export animal products in epidemic areas; it is forbidden to eat milk and meat from sick animals. '

Protection of susceptible persons: For high-risk groups, inoculate live attenuated live vaccines of Bacillus anthracis once a year. Vaccination of susceptible animals in the affected area is conducted once a year in early spring. In addition, we should vigorously publicize the harmfulness of anthrax, transmission routes and control methods.

Biological Harmful Brucellosis

Brucellosis is a zoonotic infectious disease caused by Brucella. It is common in pastoral areas and is one of the legal occupational diseases in China.

1. Etiology and pathogenesis

Brucella is a Gram-negative short globular bacillus with no flagellum, no spores or capsules, and can be divided into 6 species and 19 biotypes. Pathogenicity to humans includes Brucella malta (sheep species), Brucella abortus (bovine species), Brucella suis, and Brucella canis. Among them, sheep pathogens are the most pathogenic and most common. The bacteria has a strong resistance to the external environment, but is sensitive to sunlight, heat and commonly used disinfectants.

The pathogenesis of this disease is relatively complex, and bacteria, toxins, and allergies all participate in the occurrence and development of the disease to varying degrees. The pathological changes of this disease are extensive, and the damaged tissue includes almost all organs and tissues. The lesions of the monocyte-macrophage system are the most significant. Can cause bacteremia, sepsis or toxemia. The pathogenic bacteria growing in the mononuclear-macrophage system enter the blood flow multiple times, causing clinical symptoms to repeatedly aggravate, forming a wave-type heat pattern.

2.Epidemiology

Brucellosis is endemic in many countries and regions in the world. China is mainly endemic in pastoral areas such as northwest, northeast, and Inner Mongolia. In recent years, the annual incidence of brucellosis in China is about 30,000. The disease can occur throughout the year, and the peak period is late spring and early summer.

(1) Source of infection

Mainly diseased animals, mainly sheep, followed by cattle and pigs, dogs, deer, horses, camels, etc. can also become sources of infection. Many wild animals can also be used as hosts, such as wild deer and bison. Brucellosis is often transmitted first in domestic or wild animals and then in humans.

(2) Transmission

It mainly penetrates the body through the skin and mucous membranes, the digestive tract and the respiratory tract. Severe abortion or stillbirth of sick animals and amniotic fluid, placenta, postpartum vaginal secretions contain a large amount of Brucella. If lambs are delivered and assisted with abortion, if there is no protective measures, the disease will be easily infected through the skin. Contamination of fur, soil, and water sources with bacterial contaminants can indirectly infect humans and livestock. The disease can be transmitted by slaughtering and disposing of carcasses, ingestion of milk, meat and internal organs of sick animals, and by aerosols inhaling human infections.

(3) Susceptible people

The population is generally susceptible to this disease, and it is more common in young adults. Herdsmen, slaughter workers, meat packers, veterinarians and other professional groups have more opportunities to contact and be infected with Brucella. Although there is some immunity after the disease, but it is not stable, and the patient can be repeatedly infected with Brucella.

3. Clinical manifestations

The clinical manifestations of this disease are complex and diverse. The incubation period is generally 1 to 3 weeks, with an average of two weeks, with a minimum of only 3 days and a maximum of 1 year. The course of disease can be divided into acute phase, subacute phase and chronic phase. The acute phase refers to illness within 3 months; the subacute phase ranges from 3 to 6 months; and the chronic phase exceeds 6 months.

(1) Acute phase and subacute phase

Mainly manifested as fever, sweating and joint muscle pain. The most common types of fever are irregular heat and relaxation heat. The typical heat type is wave heat, but it is rare now. Hyperhidrosis is the main symptom of this disease, and there may be heavy sweating at night or in the early morning when fever is reduced. Joint pain is more obvious, which is caused by arthritis, which mostly occurs in large joints and is migratory. Physical examination reveals enlarged liver, spleen, and lymph nodes. Endocarditis, severe neurological complications, etc. are the main causes of death.

(2) chronic period

Main manifestations are fatigue, general discomfort, joint muscle pain, low fever, and depression. Can also be seen in chronic arthritis, neuritis, and chronic damage to the genitourinary system.

4.Diagnosis

The diagnosis of human brucellosis should be based on the patient's epidemiological contact history, clinical manifestations, and laboratory tests. According to China's "Brucilliosis Diagnostic Standard (WS269-2007)" can be graded diagnosis. According to the diagnostic standards for occupational infectious diseases in China (GBZ227-2010), confirmed cases with a history of occupational exposure can be diagnosed as occupational brucellosis ^[2] .

5. Prevention principles

(1) Treatment

Acute phase and subacute phase mainly adopt comprehensive measures combining symptomatic treatment and pathogenic treatment. The treatment of chronic phase is more complicated, including pathogen treatment, desensitization treatment and symptomatic treatment.

(2) Prevention

Strictly manage the source of infection: patients in the acute stage should be hospitalized and isolated for treatment until symptoms disappear and blood and urine cultures are negative. Patients' excreta and pollutants should be disinfected; all sheep, cattle and pigs in the epidemic area should be quarantined regularly. Any livestock that is positive should be slaughtered or kept in isolation. The imported livestock should also be quarantined to prevent the occurrence of imported brucellosis.

Cut off the transmission route: The sites, utensils, and pens contaminated by sick animals and their excreta, secretions, etc. should be disinfected. Strictly prevent food and water sources from contaminating bacterial sewage. It is forbidden to sell and consume sick animal meat and milk. Strengthen the hygiene supervision of animal products. Raw milk should be sold after pasteurization, and drink after boiling. The furs in the affected areas need to be quarantined before they can be sold.

Protect susceptible people: Individuals who are susceptible to occupation should strengthen personal protection, wear work clothes, masks, hats, gloves, etc. at work, avoid direct contact with the skin and diseased animals and their pollutants as much as possible, and prevent the delivery of lambs without hands; Personal protective equipment should be strictly disinfected. Vaccination of high-risk groups can be carried out. Vaccination of domestic animals in endemic areas can prevent the disease from spreading.

Biological harmful factors occupational forest encephalitis

Forest encephalitis, also known as tick-borne encephalitis, is a natural epidemic disease caused by forest encephalitis virus via the tick vector. Occupational forest encephalitis is a form of occupational forest encephalitis in which workers are engaged in professional activities in forest areas.

1. Etiology and pathogenesis

Forest encephalitis virus belongs to the flavivirus genus Flaviviridae, and its morphology, structure, and resistance are similar to that of JE virus. The virus is resistant to low temperatures, not resistant to external factors, and sensitive to high temperatures and disinfectants. After the virus invaded the body, most patients presented with a recessive infection or a mild clinical manifestation. The pathological changes of this disease are similar to that of JE, and there are extensive inflammatory lesions in the nervous system. Nerve cells have degeneration, necrosis, and softening of brain tissue. The lesions involve the brain, mesencephalon, brain stem, and spinal cord. In severe cases, the medulla oblongata can die due to respiratory failure.

2.Epidemiology

The disease has obvious regional, seasonal and occupational characteristics. Popular in the Russian Far East, Eastern Europe, Central European countries, and the forest areas of Northeast and Northwest China. The high season in China is from May to August. Ticks and wild rodents are the main sources of infection; cattle, horses, dogs, and sheep can be infected and become the source of infection after being bitten by ticks. The disease is mainly transmitted by tick blood. Humans are generally susceptible. All patients are related to forest operations. They are more common in occupational groups such as logging, exploration, hunting, and medicine collection. They are stationed in the forest area, and the outdoor tourists are easy to learn infection.

3. Clinical manifestations

The incubation period is generally 7 to 14 days, with the shortest 1 day and the longest 30 days or more. Most patients have an acute illness. It is clinically characterized by central nervous system symptoms such as sudden high fever, meningeal irritation, disturbance of consciousness, and paralysis. The case fatality rate is higher. Clinical is generally divided into frustrated, light, ordinary and heavy.

4.Diagnosis

According to the occupational population working in forest areas in the spring and summer seasons with a history of tick bites, sudden fever, clinical manifestations of typical acute central nervous system injury, and specific serological tests, refer to the results of on-site forest encephalitis epidemiological survey for comprehensive analysis , And exclude similar diseases caused by other causes before diagnosis. According to the diagnostic criteria of occupational forest encephalitis in China (GBZ88-2002) ^[3] , it can be used for graded diagnosis.

5. Prevention principles

(1) There is no specific treatment for this disease at present, symptomatic treatment and supportive therapy are still the main measures to treat this disease.

(2) Prevention

Eliminate the source of infection: ecologically affect the activities of wild animals, monitor the natural epidemic source, and strengthen the work of preventing rodent, rodent and tick.

Cut off the transmission route: Forestry workers entering the epidemic area should protect the surrounding environment of the workplace, remove weeds on the roadside, and reduce the chance of being attacked by ticks; do a good job of personal protection, and tighten the cuffs, neckline, trousers, etc. To prevent tick bites.

Protect vulnerable groups: Vaccination can effectively prevent forest encephalitis. Those who enter the forest area should complete the vaccination before March; its validity period is about 1 year. Forest workers need to be vaccinated repeatedly every year ^[4] . ·