Q fever

Q heat introduction QFever is an acute natural epidemic disease caused by Rickettsiaburneti (Coxiellaburneti). The clinical features are sudden onset, fever, fatigue, headache, myalgia and interstitial pneumonia, and no rash. In 1937, Derrick discovered and first described it in Queensland, Australia. Because the reason was unknown at the time, the disease was called Q fever. basic knowledge The proportion of illness: 0.005%-0.008% Susceptible people: no specific population Mode of infection: respiratory tract transmission, contact transmission, digestive tract transmission Complications: joint pain, pleurisy, pleural effusion, pericarditis, myocarditis, myelitis

Q fever

Cause:

The basic characteristics of Bernard rickettsia (Q rickettsia) are the same as those of other rickettsia, but have the following characteristics: 1. It has a filterability. 2. Multiply in the host cell vacuoles. 3. Does not contain X-aggregates that cross-react with Proteus X strain. 4. There is generally no acute poisoning reaction in laboratory animals. 5. It has strong resistance to physical and chemical factors. It can survive for 7 to 9 months at 4-6 °C in dry sand, can live for several years at -56 °C, and can be inactivated by heating at 60-70 °C for 30-60 minutes.

Q heat is distributed worldwide and is maintained by recessive infections in livestock or farm animals. Sheep, cattle and goats are the main source of human infection. Bernard Rickettsia is found in feces, urine, milk and tissues (especially It is a placenta), so it is easy to form infectious aerosols. Bernatrick's corpuscles are maintained in nature through animal-clam circulation. Various arthropods, rodents, other animals and birds can be infected and transmitted to humans. Bernatrick's corpuscle enters the human body from the respiratory mucosa, first propagates in the local reticuloendothelial cells, and then enters the blood to form rickettsial blood. It spreads all tissues and organs of the whole body, causing small blood vessels, lung and liver tissues. Organ diseases, vascular lesions mainly have endothelial cell swelling, may have thrombosis, lung lesions are similar to virus or mycoplasma pneumonia, bronchiol alveolar fibrin, exudate composed of lymphocytes and large mononuclear cells, severe Similar to lobar pneumonia, there are reports of inflammatory pseudo-lung tumors caused by Q-Herlikids in foreign countries. The liver has extensive granulomatous infiltration, heart can develop myocarditis, endocarditis Pericarditis, and can be formed violations valve vegetation, or even lead to rupture of the main A sinus, valve perforation, other spleen, kidney, testis lesions can also occur.

Cases are found in occupational workers who are in close contact with farm animals or their products. The route of transmission is inhalation of infectious aerosols, and drinking contaminated raw milk can also cause disease.

Q heat prevention

(1) Management of infectious sources

Patients should be isolated, sputum and urine should be disinfected, attention should be paid to the management of livestock and poultry, so that pregnant animals are separated from healthy animals, and the excrement, placenta and its polluted environment during the delivery period of livestock are strictly disinfected.

(2) Cut off the route of transmission

1. Slaughterhouses, meat processing plants, furry tanneries, etc., and workers who have close contact with livestock must work in accordance with the protection regulations.

2. Destroy the rodent.

3. For suspected infected cattle and goat milk, it must be boiled for 10 minutes before drinking.

(3) Autoimmune

Workers who have more exposure to livestock can be vaccinated to prevent infection, livestock can also be vaccinated to reduce the incidence rate, and the local response of the dead vaccine is large; the attenuated live vaccine is used for skin scratches or sugar pills, no bad The reaction has a good effect.

Q thermal complications Complications, joint pain, pleurisy, pleural effusion, pericarditis, myocarditis, myelitis

Common complications are:

Joint pain

2. Even with pleurisy, pleural effusion;

3. Pericarditis, myocarditis, cardiopulmonary infarction, meningoencephalitis, myelitis, interstitial nephritis, etc.;

4. Serious people can cause death.

Q heat symptoms common symptoms fatigue relaxation heat fatigue liver swelling night sweats abdominal pain breathing difficulties lung or bronchial weeks ... nausea liver function check bilirubin ...

The incubation period is 12 to 39 days, with an average of 18 days. Most of the onset is rapid, and a few are slower.

(a) fever

At the beginning, with chills, headache, myalgia, fatigue, fever rose to 39 ~ 40 ° C within 2 to 4 days, showed a relaxation heat type, lasting 2 to 14 days, some patients have night sweats, in recent years, many patients were found Return to hot performance.

(two) headache

Severe headache is a prominent feature of this disease, more common in the forehead, posterior orbital and occipital, often accompanied by myalgia, especially the psoas, gastrocnemius, and joint pain.

(c) pneumonia

About 30 to 80% of patients have lung lesions. On the 5th to 6th day of the disease, dry cough, chest pain, a few mucus or bloody sputum, signs are not obvious, sometimes small wet rales can be heard, X-ray examination often finds the lungs. There are segmental or large-leaf blurred shadows around the lower lobe, and the texture of the lungs or the bronchi can be thickened and infiltrated. Similar to bronchial pneumonia, the lung lesions are most prominent on the 10th to 14th day of the disease, disappearing in 2 to 4 weeks. Even with pleurisy, pleural effusion.

(four) hepatitis liver love tired

More common, patients with anorexia, nausea, vomiting, right upper abdominal pain and other symptoms, liver enlargement, but the degree is different, a few can reach 10cm under the costal margin, tenderness is not significant, some patients have splenomegaly, liver function check bilirubin And transaminase is often increased.

(5) Endocarditis or chronic Q fever

About 2% of patients have endocarditis, long-term irregular fever, fatigue, anemia, clubbing, heart murmur, difficulty breathing, secondary valvular lesions are more common in the aortic valve, mitral valve can also occur, with the original Related to rheumatism, chronic Q fever refers to acute Q fever after the disease lasts for several months or more, is a multi-system disease, can occur pericarditis, myocarditis, cardiopulmonary infarction, meningoencephalitis, myelitis, interstitial nephritis, etc. .

Q hot check

Laboratory inspection

Blood picture

The blood cell count is normal, the neutrophils are slightly shifted to the left, the platelets can be reduced, and the erythrocyte sedimentation rate is moderately increased.

2. Serology

(1) Complement binding test: acute Q-hot phase II antibody is increased, phase I antibody is low, if single serum phase II antibody titer has a diagnostic value of 1:64 or more, 2 to 4 weeks after the disease, double serum The titer is 4 times higher and can be diagnosed. Chronic Q fever, phase I antibody is equivalent to or exceeds the level II antibody level.

(2) Microagglutination test: Phase I antigen was converted to phase II antigen by trichloroacetic acid treatment, and stained with hematoxylin and stained with patient serum on a plastic plate. This method is more sensitive than complement fixation test, and the positive rate (first) The positive rate of 50% in one week and 90% in the second week) can also be measured by capillary agglutination test, but the specificity is not as good as the complementary test.

(3) Immunofluorescence and EliSA detection Q thermo-specific IgM (anti-II phase antigen): can be used for early diagnosis.

3. Pathogen separation

Blood, sputum, urine or cerebrospinal fluid material was injected into the abdominal cavity of guinea pigs. The serum complement-binding antibody was measured within 2 to 5 weeks, and the titer was observed. At the same time, the animals had fever and splenomegaly. The spleen tissue and spleen surface infiltration were taken by necropsy. Liquid smear staining microscopic examination of pathogens; rickettsia can also be isolated by chicken embryo yolk sac or tissue culture method, but must be carried out in a conditional laboratory to avoid infection in the laboratory.

Q thermal diagnosis

diagnosis

Diagnosis can be based on the cause, symptoms and related tests.

Differential diagnosis

1. Acute Q fever should be differentiated from influenza, brucellosis, leptospirosis, typhoid fever, viral hepatitis, mycoplasmal pneumonia, and parrot fever.

2.Q endocarditis should be differentiated from bacterial endocarditis: any endocarditis manifestations, blood culture multiple negative or accompanied by hyperbilirubinemia, hepatomegaly, thrombocytopenia (<100,000 / Mm3) should consider Q endocarditis, supplementation test I phase antibody > 1 / 200, can be diagnosed, foreign reports, direct fluorescence detection I, II phase IgA is high titer, used to diagnose Q endocarditis Other manifestations of chronic Q fever should also be differentiated from the disease caused by the corresponding cause.

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