What Are the Different Modes of Malaria Transmission?

Malaria is a vector-borne infection caused by Plasmodium infection through the bite of Anopheles mosquitoes or transfusion into the blood of a person carrying Plasmodium. There are four types of Plasmodium parasites in the human body, namely P. vivax, P. vivax, P. falciparum, and P. ovale. Plasmodium vivax and Plasmodium falciparum are the main species in China; the other two species are rare, and some cases imported abroad have occasionally been seen in recent years. Different Plasmodium causes Plasmodium vivax, P. malariae, P. falciparum and P. ovale. The disease is mainly manifested as periodic attacks, coldness, fever, and sweating throughout the body. After long-term multiple attacks, it can cause anemia and splenomegaly.

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2019-11-30 12:11 Guangxi announces official elimination of malaria

On November 29, the feedback review meeting for the final review of malaria elimination in Guangxi was held in Nanning. After rigorous review by the experts of the National Malaria Elimination Final Evaluation Evaluation Team, it was finally announced thatGuangxi passed the National Malaria Elimination Final Evaluation, marking that Guangxi has reached the standards for malaria elimination. ... more

Basic Information

English name: malaria
Visiting department: Infectious Diseases
Common causes: Infection by Anopheles mosquito bite or blood transfusion

Common symptoms: Periodic attacks, chills, fever, sweating, anemia and splenomegaly
Contagious: Have
way for spreading: Spread by infected anopheles bites

Causes of malaria

Source of infection: patients with present malaria or asymptomatic carriers who have gametophytes in their blood become the source of infection. The higher the density of the protozoa in the blood, the higher the density of the gametophyte, and the greater the chance of transmission.

Clinical manifestations of malaria

Incubation period

From human infection to onset of Plasmodium (oral temperature exceeding 37.8 ° C), the incubation period is said. The incubation period includes the first reproductive cycle of the entire infrared period and the inner red period. Generally, malaria vivax and oval malaria are 14 days, malarial malaria is 12 days, and malaria malaria is 30 days. The number of infected protozoa varies, the number of strains, the difference in human immunity, and the different ways of infection can cause different incubation periods. Temperate regions have so-called long-latency worm strains that can last up to 8 to 14 months. The incubation period of transfusion infection is 7-10 days. Fetal malaria has a shorter incubation period. The incubation period can be prolonged for people who have some immunity or who have taken preventive medicine.

2. Cold period

The chills first caused coldness at the ends of the extremities, and the back and body became cold. Goose bumps on the skin, cyanosis on lips, nails, pale faces, and sore muscles and joints throughout the body. As a result, the whole body trembled, teeth trembled, and some people could not stop covering a few quilts. It lasted for about 10 minutes or even an hour, and the chill stopped naturally and the temperature rose. Patients often feel severely ill at this stage.

3. Fever period

After the cold sensation disappears, the complexion turns red, the cyanosis disappears, and the body temperature rises rapidly. Generally, the more pronounced the coldness, the higher the body temperature, which can reach above 40 ° C. Patients with high fever are suffering. Some are restless and have more than purine; some are delirious, get empty, and even twitch or unconscious; some have severe headaches and stubborn vomiting. The patient's face was red and short of breath; conjunctival congestion; the skin was hot and dry; the pulse was rapid and rapid; the urine was short and dark. Talk about palpitations, thirst, and cold drinks. It lasts 2 to 6 hours, and more than 10 hours in individual cases. Herpes on the lips and nose is common after several episodes.

4. Sweating period

In the later period of high fever, the face and palms of the hands sweat slightly, and then the whole body is sweating, the clothes are soaked, and the body temperature decreases in 2 to 3 hours, often to 35.5 ° C. The patient felt comfortable, but was very sleepy and often fell asleep. When I wake up, my spirit is light, my appetite is restored, and I can work as usual. At this moment enters the interim period.

Malaria check

Blood image

Red blood cells and hemoglobin decrease after multiple episodes, especially for malaria; the total number of white blood cells may increase slightly at the beginning, and then normal or slightly lower. The number of monocytes classified by white blood cells often increases, and granulose particles are seen phagocytosed.

2. Plasmodium inspection

Blood smear (thin or thick) is stained for Plasmodium. And can identify the species of Plasmodium. Bone marrow smear staining showed a positive rate for Plasmodium.

3. Serology

Antimalarial antibodies generally appear 2 to 3 weeks after infection, peak at 4 to 8 weeks, and then gradually decline. Indirect immunofluorescence, indirect hemagglutination and enzyme-linked immunosorbent assays have been applied, and the positive rate can reach 90%. Generally used for epidemiological examination.

Malaria diagnosis

Epidemiology

Fever patients with a history of living or traveling in an endemic area, a history of malaria in recent years, or a recent transfusion of blood should be suspected.

2. Clinical manifestations

Typical periodic chills, fever, and sweating can be diagnosed initially. Irregular fever, accompanied by spleen, liver enlargement and anemia, should consider the possibility of malaria. The most dangerous type occurs in the epidemic period, and it is usually caused by anxiety, high fever, chills, coma and convulsions. Suddenly high fever, chills, and coma in infants and young children in endemic areas should also consider this disease.

3. Laboratory inspection

It is mainly a search for Plasmodium, which is usually found to confirm the diagnosis. Blood smears should be collected during the onset of a chill in order to find the Plasmodium. At this time, the number of protozoa is large and easy to find. Repeat the search as many times as necessary. And be sure to do a thick blood film search. If the clinical suspicion is high and the blood film is negative several times, a bone marrow puncture smear can be used to look for Plasmodium.

4. Molecular biology technology diagnostics

(1) The sensitivity and specificity of polymerase chain reaction (PCR) detection are high. The PCR detection method has been developed into a variety of methods based on the original, such as nested PCR, reverse transcriptase PCR, PCR-ELISA and so on. In addition to direct detection of Plasmodium in blood samples, Plasmodium can also be detected on filter paper dried blood drops. It has progressed from detecting P. falciparum to detecting P. vivax.

(2) DNA probe detection DNA probe detection has good specificity and stability.

5. Therapeutic diagnosis

The clinical manifestations are very similar to malaria, but after repeated inspections no Plasmodium was found. Try a drug that kills the protozoa in the red stage (such as chloroquine). For 48 hours, the fever control may be malaria. But pay attention to chloroquine-resistant strains.

Differential diagnosis of malaria

Malaria that is not symptomatic or other diseases suspected of malaria should be identified. Malaria has fever and liver and splenomegaly symptoms and should be distinguished from other diseases with this characteristic symptom.

1. Identification with common diseases

(1) In the past history of schistosomiasis , there has been contact with epidemic water and a history of cercaria dermatitis in schistosomiasis endemic areas. Fever and liver, splenomegaly, gastrointestinal symptoms include diarrhea, bloody stools, etc. Eosinophils are common. Tests for schistosomiasis kits showed positive antibodies and antigens.

(2) Amoebic liver abscess with irregular fever, markedly enlarged liver and marked tenderness, increased white blood cell count, most of which are neutrophils, and a mass on ultrasound examination.

(3) Severe chills or chills, high fever, enlarged liver and spleen. Migratory abscesses can occur, with significant increases in white blood cells and neutrophils. Generally can be asked about the cause and process of infection. Blood bacterial culture was positive.

(4) Typhoid fever is relaxation fever at the beginning, followed by remnant fever or relaxation fever, rose rash, gastrointestinal symptoms and systemic poisoning symptoms can be seen. Blood, bone marrow, fecal urine cultures were positive, and Federer's response was positive.

(5) Leptospirosis has a characteristic of relaxation fever or persistent fever, with gastrocnemius pain. Hemorrhage of the skin and mucous membranes, and enlarged liver and spleen may occur. Serum immunological test was positive.

(6) Irregular fever with acute pyelonephritis , backache, frequent urination or pain. Red, white blood cells and protein appeared in the urine, and urine culture was positive.

(7) Brucellosis flaccid fever and orchitis are one of the characteristic symptoms. The spleen is enlarged and tender. Serum agglutination test or ELISA test was positive.

(8) Viral infections such as influenza, fever, and chills are often accompanied by obvious symptoms of upper respiratory infections. Another example is dengue fever, high fever with chills, liver, splenomegaly, extremities and trunk rash. Some virus infections have irregular fevers, and the cause has not been found in various aspects. Using molecular biology techniques to test, a positive result of a virus was detected.

2. Identification from coma other than cerebral malaria

Meningitis, encephalitis, epilepsy, brain abscess, brain tumor, cerebrovascular accident, trypanosomiasis in the tropics, sickle cell disease, etc. can all cause coma. If the clinical manifestations and laboratory diagnosis results are comprehensively analyzed, do not It is difficult to determine whether a coma caused by cerebral malaria. However, at least at this stage, cerebral malaria is the first disease to be considered for those who have recently lived in malaria-endemic areas such as Africa and Southeast Asia and have symptoms of coma.

Malaria treatment

Basic treatment

(1) Bed rest should be taken during the onset and 24 hours after fever.

(2) Pay attention to the supply of water, give a liquid or semi-liquid diet to those with poor appetite, and give a high-protein diet to the recovery period; those who can't eat due to diarrhea should be replenished appropriately; those with anemia can be supplemented with iron

(3) Pay attention to keep warm during the chills; use a dry towel or a warm and wet towel to dry the sweat in a timely manner, and change the sweaty clothes at any time to prevent the cold; use physical cooling when the fever is high, and patients with excessive fever can not tolerate the drug temperature due to the high fever ; Dangerous fever should closely observe the condition, timely detect changes in vital signs, record the amount of in and out, and do basic care

(4) Isolate according to arboreal infectious diseases. The syringe used by the patient should be washed and disinfected.

2. Pathogen treatment

The purpose is to kill both the Plasmodium in the red stage to control the outbreak, to kill the Plasmodium in the infrared stage to prevent recurrence, and to kill the gametophyte to prevent transmission.

(1) Treatment of P. vivax, P. vivax and O. malaria: including cases of recurrent disease and cases of relapsed P. vivax, it is necessary to use blood schizont killing drugs such as chloroquine to kill protozoa in the red stage and quickly retreat. Heat, and the use of tissue-phase schizont killing drugs also called radical medicine or anti-relapse medicine for radical cure or anti-relapse therapy, killing the infrared-phase protozoa. Commonly used in combination with chloroquine and primary aminoquine.

(2) Treatment of falciparum malaria: In areas that have not yet developed resistance to chloroquine, chloroquine can still be used to kill protozoa in the red blood cell stage. At the same time, gametophyte killers must be added. Adults take chloroquine plus primary aminoquine.

3. Rescue principles for dangerous outbreaks

(1) Kill Plasmodium asexuals quickly;

(2) Improve microcirculation and prevent capillary endothelial cells from breaking down;

(3) maintaining hydropower balance;

4.Fast and efficient antimalarial drugs are available

Artemisinin and artesunate.

5. Other treatments

(1) People with circulatory dysfunction should be treated according to septic shock, and given corticosteroids, tinctures, heparin, etc., with low scores of dextran

(2) Patients with high fever convulsions, given physical, drug cooling and sedation

(3) Cerebral edema should be dehydrated; heart failure, pulmonary edema should be strong diuresis; respiratory failure, respiratory stimulants, or artificial respirators; severe renal failure can be used for hemodialysis

(4) Black urine fever is the first to stop quinine and primary quinine, followed by hormones, alkalized urine, diuresis and so on.

Malaria prevention

Malaria prevention refers to the protection of susceptible people. Including individual prevention and group prevention. Individual prevention is the protection measures taken by residents of the malaria area or individuals who have entered the malaria area for a short period of time in order to prevent mosquito bites, prevent morbidity or reduce clinical symptoms. Mass prevention is to prevent populations with high malaria, endemic outbreaks, or large numbers of people who have lived in the malaria for a longer period of time. In addition to the purpose of including individual prevention, it must also prevent transmission. According to the weak links in the transmission channels, it is necessary to choose protective measures that are economical, effective, and easily accepted by the masses.