Pine caterpillar osteoarthritis

Introduction to pine caterpillar osteoarthritis Pine caterpillar osteoarthritis is a seasonal regional outbreak epidemic disease discovered in various provinces in southern China in recent years. It is a disease mainly involving skin, bone and joints. The epidemiological investigation and animal experiments have proved that the disease is related to contact with pine caterpillars, so it is named pine caterpillar disease. In terms of the incidence, there are reports in nine provinces including Guangdong, Fujian, Guangxi, Hunan, Hubei, Anhui, Zhejiang, Jiangxi, and Jiangsu. In 1970, employees of a kiln factory in Jinhua, Zhejiang Province used pine with pine caterpillars. The incidence of twigs burning kiln was the earliest reported case in China. In 1975, 4010 cases occurred in Chaoyang, Guangdong, accounting for 5.54% of the total population. The incidence of exposure to pine caterpillars was 52.9%-86.4%. The onset time is the peak season of summer and autumn, and the most is in October. The patients range from 8 months to 84 years old, among which young adults aged 20 to 50 are the most common. There is no difference in the incidence of men and women, which varies mainly depending on the composition of the population. Most of the affected areas are in the mountainous areas, mainly in areas with pine forests and pine caterpillars. Most of the cases are in the mountains, cutting firewood, hitting pine branches, collecting pine caterpillars, cutting rice in polluted rice fields, and students touching pines when going up the mountain. Caterpillars may also be caused by exposure to weeds contaminated by pine caterpillars, clothing and water. basic knowledge The proportion of illness: 0.0002%-0.0005% (more common in teenagers) Susceptible population: the most common among young adults aged 20 to 50 Mode of infection: non-infectious Complications: dermatitis

The cause of pine caterpillar osteoarthritis

Poisoning (30%):

That is, after the poisonous burr enters the human skin, toxemia is caused by the toxin entering the blood circulation. It is estimated that the toxin has a strong affinity with the connective tissue, which causes the tissue surrounding the joint to react, but the toxin is injected into the subcutaneous tissue of the animal, but it cannot Animals are ill.

Allergic reaction (30%):

Many researchers have found that all patients have a history of contact with pine caterpillars or their contaminated items, and can quickly control symptoms with anti-allergic drugs in the early stages of the disease, and their X-ray findings and pathological changes in the tissues surrounding the joints are also Rheumatoid arthritis is similar and is therefore inferred to be an allergic reaction, but animal experiments are still difficult to support.

Infection (25%):

Some scholars have found that purulent fluid can be extracted from the diseased joint or skin induration of this patient, and Staphylococcus aureus, Staphylococcus aureus, Pseudomonas aeruginosa, etc., and their X-ray changes and pathological changes are consistent. The characteristics of low-toxic infections, it is inferred that under the action of pine caterpillar toxin, the vascular permeability is increased, and it is susceptible to the invasion of pine caterpillars or humans, causing low-toxic infections, but other researchers have done local fluid culture. There is no bacterial growth, and dead bones have never been found on X-ray films. Therefore, this is difficult to establish.

Although the above inferences have certain basis, they cannot clearly explain the pathogenesis of pine caterpillar disease, and further research is needed.

Pine caterpillar osteoarthritis prevention

The key to the disease is prevention. When entering a forest with a large number of pine caterpillars, especially in mountain forests, personal protection should be strengthened to avoid direct contact with pine caterpillars and their pollutants. Do not enter the water contaminated with pine caterpillars. Caterpillars and their mites should be burned intensively. After contact with pine caterpillars, they can be washed immediately with soapy water or diluted with ammonia to relieve symptoms.

Pine caterpillar osteoarthritis complications Complications dermatitis

Lateral osteoarthrosis can cause joint deformity and rigidity.

The abnormality of joint deformity is generally insidious. There is no clinical symptoms in the early stage. Some patients may show mild systemic symptoms in the early stage, such as fatigue, weight loss, long-term or intermittent low fever, anorexia, mild anemia. Due to the mild condition, most patients can not be detected early, resulting in delayed disease and loss of optimal treatment timing.

Symptoms of pine caterpillar osteoarthritis common symptoms muscle atrophy joint deformity skin temperature rise chills maculopapular loss of appetite

1. The incubation period is generally 1 to 3 days after exposure to pine caterpillars or their pollutants. Individual patients have a longer incubation period of up to 48 days.

2. Systemic symptoms: patients with systemic symptoms are mostly mild, or no systemic symptoms, may have fever, mostly between 37.5 ~ 38.5 ° C, individual up to 39 ° C, this time may have chills, headache, dizziness, general weakness and Loss of appetite and other symptoms, and gradually subsided after 2 to 3 days, regional lymph nodes, can be moved, tenderness, gradually disappeared 10 to 20 days after onset, local skin generally no ulceration.

3. Local symptoms: The exposed parts of the body are prone to onset, which is related to direct contact. The most common sites of infection are the hands, feet, wrists, ankles, etc., but can also occur in the head and neck, eyes, auricles, chest, and vertebrae. In the buttocks and perineum, a small number of patients can spread to the whole body. According to the invasion range and manifestation of the lesions, they are generally divided into the following four types:

(1) Osteoarthritis type: The incidence of this type is high, accounting for more than 55%, and the damage is great. If the treatment is not proper, it is often easy to remain dysfunction, and even lead to sickness. The most common site of the disease is the small joint bone end exposed by the extremities. The incidence of single joint is more common and asymmetrical. Only 30% of patients have multiple joint onset, or one joint symptom subsides, and the other joint develops again, which is characterized by local redness, swelling, heat, pain and dysfunction. Sometimes the pain is severe and unbearable, and it may be persistent tingling; sometimes it is paroxysmal, especially at night, affecting sleep, local non-depressed swelling, swelling of the distal limbs, flushing of the skin, temperature rise, local There are sensitive tender points, and the pain is aggravated when the joints move. This type of patients often have systemic symptoms and regional lymphadenopathy. The symptoms of large joints are generally heavier than small joints. The condition often lasts for several months or years, about 1 /5 cases have a tendency to relapse, this type can form joint deformity and rigidity in the later stage, accompanied by proximal muscle atrophy of the joint, which seriously affects the function.

(2) dermatitis type: rarer than the former, only about 25%, local manifestations of burning, itching, pain, mostly occur in exposed parts of the limbs, such as hands, feet, finger joints, etc., a few occur in the head or torso, Local skin temperature rises, flushing, mainly different types of maculopapular rash, some like urticaria, patients may have blisters between the fingers, rashes are mostly clustered or flaky, asymmetrical, 1/3 of cases There is local lymphadenopathy. After treatment, the rash is cured within 2 to 5 days; a few cases can be delayed for several months, forming chronic dermatitis, generally no systemic symptoms, and few recurrences, local residual skin pigmentation, local paralysis Grasping can enlarge the lesion or secondary infection.

(3) mass type: the lowest incidence rate, about 5%, often in the limbs or lumbosacral vertebrae and the perineum to form a local induration, accompanied by pain, no obvious boundaries, with a single hair more, the mass gradually increased, at 10 30 days to reach the peak, followed by liquefaction, fluctuations, local puncture can extract yellow-green viscous gelatinous liquid, or bloody, local symptoms can be relieved after pumping, but easy to relapse, puncture culture often without bacterial growth, this type More often accompanied by heavier systemic symptoms, the course of disease is longer, 1 to 3 months.

(4) Mixed type: the combination of the above three types of different forms, accounting for 5% to 15% of the total, depending on the region, the number of infections is different, and the proportion may vary.

Examination of pine caterpillar osteoarthritis

Blood routine examination, it can be found that: 50% to 60% of patients have increased white blood cell count, up to 10 × 109 / L; more than 60% of patients have eosinophilia; 40% to 70% of cases increased blood cell sedimentation rate Fast, the degree is directly proportional to the severity of the illness.

The joint fluid is mostly a small yellow or yellow-green viscous liquid. It contains neutrophils in the early stage and contains lymphocytes in the later stage. The bacterial culture is mostly negative. A few have Staphylococcus aureus, Staphylococcus aureus or Pseudomonas aeruginosa. Subcutaneous mass puncture can sometimes take hemorrhagic fluid. In a few cases, myocardial damage can be found when electrocardiogram is performed.

1. X-ray performance: X-ray changes of bone and joint should be displayed only 2 weeks after the onset of the disease, sometimes only after 1 month, within the acute phase of 6 months, and after 6 months, the chronic phase changes. The acute phase changes are mainly soft tissue swelling around the affected joints, osteoporosis, bone destruction and joint damage. The chronic phase changes are mainly bone hyperplasia, sclerosis and joint rigidity. The local soft tissue swelling is characterized by increased soft tissue density around the joints, and the level is unclear. The subcutaneous fat transparency is reduced; the severe ones have reticular shadows, the joint cysts are enlarged, the density is increased, and the contours are more clear. This change is mainly seen in the early stage, but it is not specific. The soft tissue shadows in the chronic phase are reduced, and it is difficult for a long time. Disappeared, a small number of cases showed small or clumpy calcification or ossified shadows in the soft tissue adjacent to the affected bone. Changes in bone and joint were osteoporosis and trabecular bone blur or interruption in the early stage, limited to the proximal joint. Bone end, similar to early osteoporosis in rheumatoid arthritis, where acute bone destruction often has one or more small round worms on one or both sides of the bone end Bad, clear boundary, common in the bone bulge area where the tendon is attached. At the same time, there may be a single layer of thin strips or irregular periosteal hyperplasia. The bone and joint changes in the late stage of the disease are mainly bone hyperplasia around the original damaged area. , hardening, the boundary of the destruction zone is clear and compact, forming a small ring-shaped stove with hardening and compactness. The bones of the hands and feet often have thickened whole bones, but there is no dead bone. In the case of unconformed bones, the damaged area can be at the epiphysis or metaphysis. , easy to cause early closure of the epiphysis.

The change of joint space is characterized by early asymmetry stenosis of the joint space, blurring, uneven articular cartilage surface, joint deformation, and even subluxation. There is often bone destruction under the cartilage. In the later stage of the disease, the joint can be found to have self-integration tendency. It can form joint stiffness, but the fusion is incomplete.

2. Other imaging examinations: Early detection of early bone and joint changes by CT and MRI.

Diagnosis and identification of pine caterpillar osteoarthritis

Generally, there is no difficulty. In the violent epidemic season and region, the diagnosis can be made according to the contact history of pine caterpillars and their pollutants, as well as the local manifestations of skin and bone joints.

For those who are unclear about the history of exposure or contact with pine caterpillars, they need to be diagnosed with rheumatoid arthritis, septic arthritis, joint tuberculosis, etc., according to the typical pine caterpillar contact history (applicable to the contact history). Diagnosis of skin and soft tissue lesions, X-ray findings of bone and joint, and joint fluid examination.

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