Overview.
Pulmonary malaria is the damage to the lungs caused by Plasmodium vivax. Infection with Plasmodium may or may not be accompanied by systemic symptoms typical of malaria as well as significant respiratory symptoms, such as coughing, sputum, shortness of breath, wheezing, or chest pain. Clinical manifestations include malarial asthma, bronchitis, pneumonia, pulmonary edema and acute respiratory distress syndrome (ARDS). The incubation period is comparable to the onset of malaria infection, 10-20 days for Plasmodium vivax and Plasmodium ovale, 70-80 days for Plasmodium vivax and 10-14 days for P. falciparum.
Causes
Patients with current malaria and carriers are the source of infection of this disease. Domestically, the disease is mainly transmitted by four species of Anopheles sinensis, Anopheles rayonii anthropophilic subspecies, Anopheles microti and Anopheles big inferior, of which the main one is Anopheles sinensis.
Symptoms
1. Incubation period
Pulmonary malaria is the lung manifestation of systemic damage of Plasmodium, and its incubation period is comparable to the onset of malaria infection, 10-20 days for Plasmodium vivax and Plasmodium ovale, 70-80 days for Plasmodium vivax, and 10-14 days for Plasmodium falciparum.
2.Types
(1) Asthma type Clinical manifestations include chills, fever, sweating, and fever receding, which is basically the same as the malaria cycle, accompanied by cough, shortness of breath, dyspnea and asthma, etc. Asthma can appear before malaria attack, throughout the onset of the disease, or even after malaria has been clinically cured. Physical examination of both lungs diffuse or scattered rales.
(2) Bronchitis type: Malaria attack with obvious cough, sputum, shortness of breath or wheezing during activity, etc. Generally, the symptoms do not fluctuate with the onset of malaria, but can be reduced with the cure of malaria, and the cough and shortness of breath may persist for a longer period of time. Physical examination of both lungs may have scattered dry or wet rhonchi.
(3) Pneumonia type is characterized by high fever, cough, hemoptysis, chest pain, shortness of breath that overlap or cross over with malaria attack, and occasionally abdominal distension, abdominal pain, diarrhea or jaundice. Dry or wet rhonchi can be heard in the lungs.
(4) Pulmonary edema type is only seen in falciparum malaria, and it has been reported that cerebral malaria is complicated by pulmonary edema as high as 50%～55%. Clinical manifestations vary according to the virulence of the worm strain, body resistance and physiological functions, ranging from a feeling of chest tightness, a little shortness of breath, light cough, to a severe cough, dyspnea, foamy sputum, pale wet and cold skin, cyanosis, and diffuse wet rhonchi in both lungs.
Examination
1. Asthma-type X-ray chest radiograph shows signs of lung hyperinflation of varying degrees.
2. Bronchitis type chest X-ray often shows lung texture enhancement, which has been reported to be present in up to 60% of patients, and some of them may also have small shadows along the direction of the lung texture.
3. Pneumonia-type X-ray chest film shows speckled or small shadows along the lung veins similar to bronchial pneumonia, or segmental or lobar shadows with unclear edges, which may be multiple or single, and are more common in the lower field. This type is easy to be misdiagnosed as bacterial pneumonia, but anti-inflammatory treatment is ineffective, and the clinical symptoms and X-ray chest film show significant improvement after antimalarial treatment for two to three days.
4. X-ray chest film of pulmonary edema type shows thickening and blurring of the texture of both lungs, butterfly-shaped shadow centered on the lung gate, and asymmetric large patchy shadows in the middle and lower fields of both lungs which can be changed according to the different positions of the body.
Diagnosis
According to: ① epidemiological data; ② typical or atypical symptoms of periodic chills, fever, sweating and fever; ③ obvious respiratory symptoms such as cough, sputum, shortness of breath, asthma, etc.; ④ X-ray chest X-ray shows enhanced lung texture or flaky shadows; ⑤ Plasmodium parasites are found in blood, bone marrow or sputum smear; ⑥ diagnosis can be made if the clinical symptoms disappear after anti-malarial treatment.
1. Peripheral blood, bone marrow or sputum smear.
Giemsa or Wright staining for Plasmodium vivax confirms the diagnosis. Patients with multiple episodes have decreased erythrocytes and hemoglobin. Reticulocytes are increased. The total leukocyte count is normal or low, monocytosis is present, and eosinophils are in the normal range. Some scholars have suggested that the peripheral blood count of leukocytes is reduced and monocytes are greater than 15%, and malaria should be considered in conjunction with the medical history.
2. Serologic examination
There are indirect immunofluorescence antibody test, indirect erythrocyte coagulation test, radioimmunoassay and enzyme-linked immunosorbent assay. For patients with very low density of malaria parasites in the blood, it is not easy to find malaria parasites by normal methods, and it has auxiliary diagnostic significance.
3. Molecular biology methods
DNA probe technology is a fast and specific method to diagnose malaria. Isotope-labeled DNA probes can detect 10pg of purified Plasmodium DNA or very low levels of Plasmodium parasitemia.
Differential diagnosis
It needs to be differentiated from influenza, sepsis, tuberculosis, bacterial pneumonia, encephalitis, etc. In particular, bronchiolitis-type pulmonary malaria disease needs to be differentiated from diffuse lung disease, both of which are characterized by cough, shortness of breath, dry or wet rales on auscultation, and increased lung texture or small patchy shadows on X-ray chest radiographs, but there is no popping sound on auscultation in the former, and restrictive ventilation dysfunction of the lungs is unremarkable, with a higher arterial partial pressure of oxygen and oxygen saturation, and a high blood Urea nitrogen value and blood lactate geometric concentration are higher, hemoglobin is low, metabolic acidosis is often present, and clinical symptoms can be relieved after antimalarial treatment.
Treatment
1. Etiologic treatment
(1) Chloroquine is a 4-aminoquinoline drug. It is absorbed quickly and completely orally, absorbed rapidly by intramuscular and subcutaneous injections, and excreted slowly, and is the drug of choice for seizure control. The main effect is to destroy the schizonts of all types of malaria parasites, except for drug-resistant Plasmodium falciparum, it has obvious efficacy on other malaria parasites.
(2) Quinine is a quinoline compound. Oral and intramuscular absorption are good, its antimalarial effect is the same as chloroquine, effective in eliminating schizonts, but worse than chloroquine. It is mainly used for cerebral malaria and drug-resistant falciparum malaria.
(3) Artemisinin and its derivatives artemether, artesunate sodium, dihydroartemisinin, etc. are the preparations firstly extracted from traditional Chinese medicine in 1971, which are effective to all kinds of malaria parasites, especially in the area where resistance to antimalarials such as chloroquine, quinine, and etanercept is increasing, the artemisinin and its derivatives are more important to the treatment of malaria. Drug fever is the main adverse effect of this class of drugs, but pregnant women should not be used except for severe cerebral malaria with resistance to chloroquine.
(4) Mefloquine 4-quinolinemethanol class of drugs. Oral absorption is good, antimalarial effect is the same as chloroquine, drug half-life up to 20 days, such as delirium, convulsions, etc., so pregnant women, infants and young children, epilepsy or a history of psychosis is prohibited.
(5) Atovaquone is a hydroxyl naphthoquinone drug. It has therapeutic effect on many kinds of protozoa, but if applied alone, malaria is easy to relapse.
(6) Primaquine is an 8-aminoquinoline compound, which is the only drug for prevention of Plasmodium vivax. The drug is completely absorbed orally, half-life is about 7h, the drug can kill Plasmodium falciparum and Plasmodium ovale schizonts and dormant bodies in liver cells, so it can prevent relapse, and it can kill the gametocytes of various malaria parasites, so it can prevent the transmission of malaria.
(7) Ethylaminopyrimidine is a diaminopyrimidine drug with complete oral absorption, slow excretion and long-lasting effect. Mainly through the inhibition of dihydrofolate reductase and inhibit the DNA synthesis of Plasmodium, and can inhibit the development of various Plasmodium gametocytes in mosquitoes, so there is a role in preventing the spread of malaria.
(8) Fosfomycin has good antimalarial activity both in vivo and in vitro, and is a new antimalarial drug with potential.
(9) Desferrioxamine In recent years, it has been proved that iron deficiency can reduce plasmodium hematopoiesis, while iron supplementation and hyperferritinemia are both favorable to the growth of plasmodium, resulting in increased incidence of malaria. Desferrioxamine-type iron chelator has obvious antimalarial effect on Plasmodium falciparum in vitro, and it is effective in clinical test, and it has effect on human Plasmodium falciparum’s extra-erythrocytic and intra-erythrocytic stages of Plasmodium falciparum.
2.Symptomatic treatment
For asthma, aminophylline, β-agonist such as salbutamol and terbutaline can be used; for severe cough, dextromethorphan or appropriate amount of codeine can be used; for hypoxemia, oxygen should be given by nasal catheter or mask; for secondary infection of lung, penicillin, the first, second and third generation cephalosporin should be used for intramuscular injection or intravenous drip depending on the pathogenic bacterium, drug sensitivity and the condition of the patient.
Prognosis
Early treatment of pulmonary malaria generally has a good prognosis.
Prevention
Eradication of existing malaria patients and malaria carriers, mosquito control, especially early spring mosquitoes and overwintering mosquitoes, prophylactic use of acetamiprid, primaquine, etc. In recent years, some people have tried to immunize the vaccine, achieved a certain degree of efficacy, but are still in the continuing test.