Malaria: Causes, Symptoms, Diagnosis, Treatment and Prevention
Malaria includes a group of acute infectious diseases that are transmitted primarily through the blood.Variants of names: intermittent fever, pallus, swamp fever.Pathological changes are caused by mosquitoes Anopheles, accompanied by damage to blood cells, attacks of fever, increased liver and spleen in patients.Contents: Historical aspects Malaria pathogens Features of the life cycle of the malarial plasmodium
The historical focus of this disease is Africa.From this continent, malaria spread all over the world.At the beginning of the 20th century, the number of cases was about 700 million a year.One in 100 infected was dying.The level of medicine of the XXI century reduced the incidence to 350-500 million cases a year and reduced the mortality rate to 1-3 million people per year.
For the first time as a separate disease, malaria was described in 1696, then the official medicine of that time proposed treatment of symptoms of the pathology with cinchona bark, which had been used by folk medicine for a long time.The effect of this medication could not be explained, because in a healthy person, quinine at the reception caused complaints similar to a fever.In this case, the principle of a similar treatment was applied, which in the 18th century was preached by Samuel Hahnemann, the founder of homeopathy.
The name of the disease familiar to us is known since 1717, when the Italian doctor Lancini established the cause of the disease, coming from the "rotten" air of bogs( mal`aria).Then there was a suspicion that the culprits are the mosquitoes.The XIX century brought many discoveries in establishing the causes of malaria, describing the cycle of development and classification of the disease.Microbiological studies have allowed to find and describe the causative agent of infection, which was called malarial plasmodium.In 1897, I.I.Mechnikov introduced pathogens into the classification of microorganisms as Plasmodium falciparum ( sporovikov class, type of protozoa).
In the 20th century, effective medicines for the therapy of malaria were developed.
Since 1942, P.G.Müller proposed the use of a powerful insecticide DDT for the treatment of the foci of disease.In the middle of the 20th century, thanks to the implementation of the global malaria elimination program, it was possible to limit the incidence to 150 million a year.Over the past decades, the adapted infection has begun a new attack on humanity.
Under normal conditions, 4 main types of microorganisms transmit human malaria.Cases of infection with this disease are described, in which pathogens are not considered pathogenic for humans.
Classical malaria clinic is called:
- P. vivax( plasmodium vivax) - a kind of plasmodium of three-day malaria;
- malarie( plasmodium of malaria) - pathogen of the variant of four-day malaria;
- falciparum( plasmodium falsiparum) - a microbe that gives rise to tropical malaria;
- P. ovale( plasmodiumum oval) is a parasite that causes an ovoid malaria( like a three-day period).
Features of the life cycle of the malarial plasmodium
The causative agent of the disease passes through two phases of its development:
- progrogonya - development of the pathogen outside the human body;
As a mosquito( female Anopheles) bites a person who is the carrier of germ cells of malaria, they enter the stomach of the insect, where the confluence of female and male gametes occurs.The fertilized egg is introduced into the submucosa of the stomach.There is maturation and division of the developing plasmodium.More than 10 thousand developing forms( sporozoites) penetrate from the destroyed wall into the insect hemolymph.
The mosquito is from now on contagious.When another person bites, sporozoites enter the body, which becomes the intermediate host of the developing malarial microorganism.The cycle of development in the body of a mosquito lasts about 2-2.5 months.
In this phase, we observe:
- Fabric stage.Sporozoites penetrate the liver cells.There they consistently develop trophozoites - schizonts - merozoites.The stage lasts from 6 to 20 days, depending on the type of plasmodia.In the human body can be introduced simultaneously different types of malaria pathogens.Schizogony can occur immediately after the introduction or after a while, even months later, which contributes to repeated returns of malaria attacks.
- Erythrocytic stage.Merozoites penetrate the erythrocyte and are transformed into other forms.Of these, 4 to 48 merozoites are obtained, then there is a morrow( exit from the damaged erythrocyte) and a second infection of healthy red blood cells.The cycle is repeated.Its duration, depending on the type of plasmodium, is 48 to 72 hours.Part of the merozoites turns into sex cells, which infects a biting human mosquito, which transmits the infection to other people.
Note: in the case of malaria infection is not from mosquitoes, but with blood transfusion containing merozoites of plasmodium, the infected person only has an erythrocyte stage.
The life cycle of the plasmodium is described in detail in the video review:
How malaria occurs
The source of the malarial infection is a sick person or carrier of germ cells of plasmodia( gametocytes).The infection comes from a bite of the vector of the disease - female Anopheles mosquito.In total, about 80 species of these parasites are known.Also, the transmission of the disease can occur in medical procedures( blood transfusion).
Children are particularly vulnerable to infection.Morbidity in the outbreaks is very high.Some people have resistance to malaria.Especially it develops after multiple infection.Immunity does not last a lifetime, but only for an indefinite period.
Please note: for malaria is characterized by seasonal onset.Summer and hot months are most favorable for vectors of infection.In a hot climate, the disease can be observed all year round.
Malaria occurs in certain foci, the tracking of which allows you to predict the beginning of a seasonal surge, its maximum and attenuation.
In classification, the outbreaks are divided into:
- is flat;
- is hilly-river;
- is a mid-river.
The intensity of transmission and spread of malaria is assessed in four types:
- is mesoendemic;
- is holoendemic.
The holoendemic type has the highest risk of infection and is characterized by the most dangerous forms of the disease.Hypoendemic type is characteristic of single( sporadic) cases of malaria.
Development of the disease and characteristic changes in the body
After penetration into the body of parasites, primary manifestations of the disease occur.Sporozoites cause tissue schizogony, which corresponds to the initial( incubation) period of development of manifestations of the disease.
Note: the main pathological reactions occur as a result of the onset of erythrocytic schizogony.
The release of parasites into the blood after the destruction of erythrocytes( measurement) is accompanied by the circulating of the protein decay products causing allergies and the action on the center of the body's thermoregulation.
The released biogenic amines contribute to the destruction of the vascular wall, cause electrolyte disturbances, irritation of the nervous system.Many components of the plasmodial life have toxic properties and contribute to the development of antibodies against them, protective immunoglobulin complexes.
The immunity system reacts by activating the protective properties of the blood.As a result of phagocytosis( destruction and "eating" of diseased cells) destruction of the damaged erythrocytes, causing anemia in the person, as well as strengthening the function of the spleen and liver, begins.The total content of blood cells( erythrocytes) decreases.
Clinically, in these stages, a person develops various types of fever.Initially they are of a wrong, non-cyclic nature, repeated several times a day.Then, as a result of the action of immune forces, one or two generations of plasmodia are conserved, which cause fever attacks after 48 or 72 hours.The disease acquires a characteristic cyclic course.
The immune response is increasing, coping with excess pathological cells and eventually the fever clinic is dying, the period of remission( remission of the disease) is coming so that then, in 1-3 months, the attack of the parasite gaining strength is repeated again.
Note: invasion process can last from 1 year to several tens of years, depending on the type of pathogen.Immunity after the transferred disease is unstable.Often there are repeated infections, but with them, fever is mild.
Against the backdrop of malaria, pathological processes occur in the brain, symptoms of swelling, damage to the walls of small vessels appear.Also, the heart suffers from severe dystrophic processes.In the kidneys formed necrobiosis.Malaria attacks the immune system, causing the development of other infections.
Symptoms of malaria
The disease occurs with periods of fever and normal exacerbations.
The main symptoms of malaria:
- fever attacks( chills, fever, sweating);
- anemia( anemia);
- enlarged spleen and liver( hepatosplenomegaly);
- decrease in the number of erythrocytes, platelets( pancytopenia).
As with most infectious diseases, three forms of malaria severity are distinguished - light, medium, heavy.
The onset of the illness is sudden.It is preceded by an incubation period( the time interval from infection to the onset of the manifestation of the disease).
It is when:
- vivax-malaria - 10-21 days( sometimes up to 10-14 months);
- four-day malaria - from 3 to 6 weeks;
- of tropical malaria - 8-16 days;
- ovale-malaria - 7-20 days.
Sometimes there is a prodromal period( time of onset of malaria, accompanied by initial, mild symptoms).The patient has - weakness, cognition, thirst, dry mouth, pain in the head.
Then abruptly appears a fever of the wrong type.
Note: the first week of the febrile period is characterized by attacks occurring several times a day.In the second week, the paroxysms acquire a clear cyclic flow with repeat in a day or two( with a four-day fever)
How the attack of the fever takes place
The duration of the paroxysm is 1-2 hours to 12-14 hours.A longer period is determined with tropical malaria.It can last a day or even more than 36 hours.
- chills - lasts 1-3 hours;
- heat - up to 6-8 hours;
- profuse sweating.Complaints and symptoms of malarial paroxysm:
- Hyperthermia - up to 41 ° C;
- severe headache;
- muscle pain;
- h Severe vomiting, severe dizziness;
- general excitement;
- pain in the lumbar region;
- face redness and sclera;
- frequent pulse;
- blood pressure decreased;
- skin is hot and dry;
- hands and feet are cold;
- on mucous faces - a manifestation of herpes sores;
- the liver and spleen are enlarged in size.
After sweating, a nap comes.During the interictal period, the patients are efficient, but over time the disease progresses, their condition worsens, weight loss, jaundice, skin becomes earthy.
The most difficult is tropical malaria.
In her case, the following symptoms of malaria are added:
- severe pain in the joints and throughout the body;
- signs characteristic of meningitis;
- delusional state of consciousness;
- attacks of suffocation;
- frequent vomiting with an admixture of blood;The pronounced increase in the liver
In the first week of the illness, seizures may leak, overlapping one another.A few months after the onset of the disease, paroxysms start to recur, but in a lighter form.
Of all the forms of malaria described, vivax is most easily followed.The highest number of relapses is observed with Chesson malaria( Pacific form).
Note: describes cases of lightning that caused death from brain edema for several hours.
Complications of malaria
The following complications may develop in attenuated or untreated patients and in the event of therapy errors:
- malarial coma;
- edematous syndrome;
- extensive hemorrhage( hemorrhage);
- different variants of psychoses;
- renal and hepatic insufficiency;
- infectious complications;Ruptured spleen
A separate complication of malaria should be noted hemoglobinuric fever .It develops against a background of massive reproduction of plasmodium, when treated with medical preparations, due to the destruction of red blood cells( hemolysis).In severe cases of this complication, to the general symptoms and complaints of an attack of malaria, a progressive decrease in the formation of urine is added.Develops fulminant renal failure, often with an early lethal outcome.
Diagnosis of malaria
Malaria is determined based on:
- collecting anamnestic data - the survey identifies previously available malaria, cases of blood transfusion to the patient;
- epidemiological history - the patient's residence in areas with existing outbreaks of the disease;
- clinical signs - the presence of characteristic complaints and a symptomatic picture of malaria;
- methods of laboratory diagnostics.
The first three items are discussed in detail in the article.Let's touch on the methods of laboratory tests.
- Clinical blood test.Vital activity of malarial plasmodium causes a decrease in the level of hemoglobin in the blood, a decrease in the number of red blood cells, a color index.The volume of erythrocyte is also lower than usual.
- Clinical analysis of urine.The appearance of hemoglobin in the urine( hemoglobinuria) and erythrocytes( erythrocyturia ) .Biochemical analysis of blood.
- .In this type of study, an increased activity of transaminases( ALT, AST) is detected, as well as an increase in the numbers of bilirubin( both fractions) and an increase in the level of albumin.
Confirm diagnosis by specific methods
To confirm the diagnosis, the blood is examined using the "thick drop" and "smear" method.
The analysis allows to determine:
- type of malarial plasmodium;
- development stage;
- level of invasiveness( number of microbes).
Invasiveness is assessed at 4 degrees( in the fields of view of the microscope):
- IV degree - up to 20 cells per 100 fields .
- III degree - 20-100 plasmodiums per 100 fields.
- II degree - no more than 10 in one field;
- I degree - more than 10 in one field.
The method is fairly simple, cheap and can often be used to monitor the condition and effectiveness of the patient's treatment.
"fine drop" analysis is assigned as an addition to the previous one in the case of the required differential diagnosis.
Express diagnostic method is the immunological assay determining the specific proteins of malarial plasmodium.It is carried out in the centers of tropical malaria.
Serological tests for malaria
Material - venous blood.
The goal is the detection of antibodies to malaria .
Evaluation of result - less than 1:20 - negative analysis;More than 1:20 - positive.
Polymerase Chain Reaction( PCR)
The test is specific in nature, allowing detection of malaria in 95% of cases.Venous blood is used.Negative point - high cost.It is necessary in doubtful cases.
Mosquitoes are also examined for the presence of malarial plasmodium cells.
Treatment of malaria
Modern methods of treating malaria are very effective.They are shown at different stages of the disease.Today, a large number of medications have been developed that can cope with the disease even in neglected situations.Let us dwell on the principles of treatment and description of the main drug groups.
Note: therapy should be started immediately after diagnosis in an infectious hospital setting.
Objectives of malaria treatment:
- destruction of pathogenic plasmodium in the patient's body;
- therapy of concomitant complications;
- warning or mitigation of a relapse clinic;
- stimulation of specific and nonspecific immunity.
Drug treatment groups for malaria treatment
The main drug groups are:
- Quinolyl methanol derivatives of Quinine, Delagil, Plakvenil, Lariam, Primachin.
- Biguanides - Bigumal.
- Diaminopyrimidines - Daraprim.
- Terpenlactone - Artesunate.
- Hydroxynaphthoquinones - MEPRON.
- Antibiotics of the tetracycline series.
- Lincosides - Clindamycin.
Malaria patients need care.Diet - 15 table on Pevzner during periods of remission and 13 table during the fever period.Recommended - lean meat and fish, soft-boiled eggs, porridge, kefir, fermented baked milk, boiled vegetables, fresh mashed fruits, juices, fruit drinks, crackers, honey.
Preventive work is carried out at the site of the infection by the application of mosquito nets, insecticides, which process places of mosquito congestion.At home, you need to use repellents, aerosols and ointments that repel mosquitoes and cause their death.
If suspected of possible infection, medicines are taken at doses prescribed by the infectious disease specialist.
Vaccine prophylaxis is currently being developed.
People who are in the outbreak of an epidemic are to be isolated and laboratory tested if there is an increased temperature.The earlier treatment is initiated, the better the result.People who come from countries with malaria foci must be examined.The infectious diseases specialist should be observed for 3 years.
For more information on the causative agent of malaria, the symptoms of the disease and current treatment methods, you will receive a video review: