Lzn symptoms. Heading into a Dangerous Season: What You Need to Know About West Nile Virus. Treating West Nile Fever

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West Nile fever

What is West Nile Fever -

West Nile fever(syn: West Nile encephalitis, West Nile encephalitis, Nile encephalitis, West Nile fever, Encephalitis Nili occidentalis - Latin; West-Nile encephalitis - English) is an acute transmissible viral disease characterized by fever, serous inflammation of the meninges (extremely rarely - meningoencephalitis), systemic lesions of the mucous membranes, lymphadenopathy and, less often, rash.

For the first time, the West Nile virus was isolated from the blood of a sick person in 1937 in Uganda. Subsequently, there were indications of a wide spread of the disease in Africa and Asia. The most common disease occurs in the Mediterranean countries, especially in Israel and Egypt. Cases of the disease are described in France - on the Mediterranean coast and in Corsica, as well as in India and Indonesia. The existence of natural foci of the disease in the southern regions of the former USSR - Armenia, Turkmenistan, Tajikistan, Azerbaijan, Kazakhstan, Moldova, Astrakhan, Odessa, Omsk regions, etc.

What triggers/Causes of West Nile Fever:

The causative agent of West Nile fever- flavivirus of group B of the togavirus family, size - 20-30 nm, contains RNA, has a spherical shape. Keeps well frozen and dried. Dies at temperatures above 56°C within 30 minutes. It is inactivated by ether and deoxycholate. It has hemagglutinating properties.

The carriers of the virus are mosquitoes, ixodid and argas ticks, and the reservoir of infection is birds and rodents. West Nile fever has a distinct seasonality - late summer and autumn. More often people of young age get sick.

The risk of the disease is higher in people over 50 years of age.. People over the age of 50 are more likely to have serious symptoms of WNV if they get sick, and they should be especially careful about mosquito bites.

Being in the air puts you at risk. The more time you spend outdoors, the longer the length of time you can be bitten by an infected mosquito. If you spend a lot of time outdoors due to work or leisure, make sure that you are not bitten by mosquitoes.

The risk of getting sick as a result of a medical procedure is very low. All donated blood is screened for the presence of WNV before use. The risk of contracting WNV through a blood transfusion or organ transplant is very low, so people who need surgery should not be put off by this risk. If you have any concerns, talk to your doctor.

Pregnancy and breastfeeding does not increase the risk of contracting West Nile fever . Researchers have not yet come to a definitive conclusion as to what risk WNV poses to a fetus or infant who becomes infected through mother's milk. If you are concerned, talk to your doctor or nurse.

Pathogenesis (what happens?) during West Nile Fever:

The pathogenesis of West Nile fever remains poorly understood.. The virus enters the blood of a person with a mosquito bite. Then the virus disseminates hematogenously, causing systemic lesions of lymphoid tissues (lymphadenopathy). When the virus penetrates the blood-brain barrier, damage to the membranes and brain substance is possible with the development of meningoencephalitis. Cases of latent infection are known.

Reservoir and sources of infection- wild and domestic birds, rodents, bats, mosquitoes, ticks.

Transfer mechanism- transmissible, carriers of the disease are mosquitoes of the genus Culex, as well as argas and ixodid ticks.

Natural susceptibility of people high. Post-infection immunity is tense and persistent.

Main epidemiological signs. The disease is endemic in many countries of Asia, Europe, Africa. Hundreds of cases of fever have been described in Israel and South Africa. The most significant African epidemic (about 3 thousand cases) was noted in the province of Cape after heavy rains in 1974. Other outbreaks were observed in Algeria, Azerbaijan, the Central African Republic, Zaire, Egypt, Ethiopia, India, Nigeria, Pakistan, Senegal, Sudan , Romania, the Czech Republic, etc. In 1999, an outbreak of fever was noted on the territory of the Volgograd region (380 people fell ill) with laboratory confirmation of the disease. Virus antigens were found in selectively caught mosquitoes of the genus Culex and ticks. The area of ​​risk for West Nile fever is the Mediterranean Basin, where birds from Africa arrive. The disease has a distinct seasonality - late summer and autumn. The disease is predominantly rural, although in France, where the disease is known as "duck fever", urban residents who come to hunt in the Rhone Valley get sick. Young people are more likely to get sick. Cases of laboratory infection are known.

Symptoms of West Nile Fever:

Incubation period ranges from several days to 2-3 weeks (usually 3-6 days). The disease begins acutely with a rapid increase in body temperature to 38-40°C, accompanied by chills. In some patients, an increase in body temperature is preceded by short-term phenomena in the form of general weakness, loss of appetite, fatigue, feelings of tension in the muscles, especially in the calves, sweating, and headaches. The feverish period lasts an average of 5-7 days, although it can be very short - 1-2 days. The temperature curve in typical cases is remittent in nature with periodic chills and excessive sweating, which does not bring patients to feel better.

The disease is characterized by pronounced symptoms of general intoxication: severe excruciating headache with predominant localization in the forehead and orbits, pain in the eyeballs, generalized muscle pain. Particularly severe pain is noted in the muscles of the neck and lower back. Many patients have moderate pain in the joints of the extremities, swelling of the joints is not observed. At the height of intoxication, repeated vomiting often occurs, there is no appetite, pain in the heart area, a feeling of fading and other unpleasant sensations in the left half of the chest appear. Drowsiness may be noted.

The skin is usually hyperemic, sometimes a maculopapular rash can be observed (5% of cases). Rarely, usually with prolonged and undulating fever, the rash may become hemorrhagic. In almost all patients, pronounced hyperemia of the conjunctiva of the eyelids and a uniform injection of the vessels of the conjunctiva of the eyeballs are detected. Pressure on the eyeballs is painful. In most patients, hyperemia and granularity of the mucous membranes of the soft and hard palate are determined. However, nasal congestion and dry cough are relatively rare. Often there is an increase in peripheral lymph nodes (usually submandibular, maxillary, lateral cervical, axillary and cubital). Lymph nodes are sensitive or slightly painful on palpation (polylymphadenitis).

There is a tendency to arterial hypotension, muffled heart sounds, a rough systolic murmur can be heard at the apex. The ECG may reveal signs of myocardial hypoxia in the region of the apex and septum, focal changes, and slowing of atrioventricular conduction. Pathological changes in the lungs are usually absent. Very rarely (0.3-0.5%) pneumonia can develop. The tongue is usually covered with a thick grayish-white coating, dryish. On palpation of the abdomen, diffuse pains in the muscles of the anterior abdominal wall are often determined. There is a tendency to stool retention. In about half of the cases, a moderate increase and sensitivity are detected on palpation of the liver and spleen. Gastrointestinal disorders can be observed (more often diarrhea like enteritis without abdominal pain).

Against the background of the clinical manifestations described above, a syndrome of serous meningitis is detected (in 50% of patients). It is characterized by a dissociation between mild meningeal symptoms (neck muscle stiffness, Kernig's symptom, less often Brudzinski's symptoms) and distinct inflammatory changes in the cerebrospinal fluid (pleocytosis up to 100-200 cells per 1 μl, 70-90% lymphocytes); a slight increase in protein content is possible. Disseminated focal neurological microsymptoms are characteristic (horizontal nystagmus, proboscis reflex, Marinescu-Radovici symptom, slight asymmetry of the palpebral fissures, decreased tendon reflexes, absence of abdominal reflexes, diffuse decrease in muscle tone. Some patients have symptoms of radiculoalgia without signs of prolapse. Actually, encephalitic symptoms are observed extremely rarely, but for a long time, signs of mixed somatocerebrogenic asthenia persist (general weakness, sweating, depression of the psyche, insomnia, memory loss).

Neuroinfectious form of West Nile fever. The most common lesion. It is characterized by an acute onset with an increase in body temperature up to 38-40 ° C, chills, weakness, increased sweating, headaches, sometimes arthralgia and back pain. Constant signs include nausea, repeated vomiting (up to 3-5 times a day), not associated with food intake. Less often, significantly pronounced symptoms of toxic encephalopathy are observed - excruciating headache, dizziness, psychomotor agitation, inappropriate behavior, hallucinations, tremor. Clinical manifestations of meningism, serous meningitis, and in some cases, meningoencephalitis may develop. The duration of fever varies from 7-10 days to several weeks. After its decrease by the type of accelerated lysis during the period of convalescence, the condition of patients gradually improves, but weakness, insomnia, depression of mood, weakening persist for a long time! memory.

Flu-like form of West Nile fever. It proceeds with general infectious symptoms - fever for several days, weakness, chills, pain in the eyeballs. Sometimes patients complain of a cough, a feeling of soreness in the throat. On examination, the phenomena of conjunctivitis, scleritis, bright hyperemia of the palatine arches and the posterior pharyngeal wall are noted. At the same time, dyspeptic phenomena are possible - nausea, vomiting, frequent loose stools, abdominal pain, sometimes enlargement of the liver and spleen. In general, this form of the disease proceeds as an acute viral infection and is often accompanied by meningism.

Exanthematous form of West Nile fever. Seen much less frequently. The development of polymorphic exanthema (usually maculopapular, sometimes roseola-like or scarlatiniform) on the 2nd-4th day of the disease is characteristic against the background of a febrile reaction and other general toxic symptoms, catarrhal manifestations and dyspeptic disorders. The rash disappears after a few days, leaving no pigmentation. Polyadenitis is often observed, while the lymph nodes are moderately painful on palpation.

Serious symptoms are rare. Approximately one in 150 people infected with the WNV virus has a severe form of the disease. Severe symptoms include: high fever, headache, neck stiffness, stupor, disorientation, coma, trembling, convulsions, muscle weakness, loss of vision, numbness, and paralysis. These symptoms may persist for several weeks, and the neurological impact may be permanent.

Milder symptoms occur in some people. Up to 20% of people who become infected experience symptoms that include: high fever, headache, muscle pain, nausea, vomiting, and sometimes swollen lymph glands or skin rash on the chest, abdomen, and back. These symptoms may persist for only a few days, although there are cases when even in healthy people the disease lasted several weeks.

Most people experience no symptoms. Approximately 80% of people (about 4 out of 5) who become infected with the WNV virus show no symptoms at all.

Complications
In the neuroinfectious form of the disease, edema and swelling of the brain, cerebrovascular accidents can develop. With the development of meningoencephalitis, paresis and paralysis are possible, a severe course of the disease with a fatal outcome in rare cases.

Diagnosis of West Nile Fever:

Diagnosis and differential diagnosis based on clinical, epidemiological and laboratory data. The main clinical signs are: acute onset of the disease, a relatively short febrile period, serous meningitis, systemic lesions of the mucous membranes, lymph nodes, organs of the reticuloendothelial system and the heart. Rarely, a rash may occur.

Epidemiological prerequisites may be staying in an area endemic for West Nile fever - North and East Africa, the Mediterranean, the southern regions of our country, information about mosquito or tick bites in these regions.

General blood and urine tests, as a rule, do not reveal pathological changes. Leukopenia may be observed, in 30% of patients the number of leukocytes is less than 4-109 / l. In the cerebrospinal fluid - lymphocytic pleocytosis (100-200 cells), normal or slightly elevated protein content. Laboratory interpretation is provided by serological reactions of RTGA, RSK and RN by the method of paired sera. However, since many flaviviruses have a close antigenic relationship, the detection of antibodies to one of them in blood sera may be due to the circulation of another virus. The most reliable evidence of a West Nile virus infection is the detection of the pathogen. From the patient's blood, the virus is isolated in MK-2 cell culture and in mice weighing 6-8 g (intracerebral infection). Identification of the pathogen is carried out by the direct method of fluorescent antibodies using a species-specific luminescent immunoglobulin to the West Nile virus.

Differential diagnosis should be carried out with other arbovirus infections, mycoplasmosis, ornithosis, listerellosis, toxoplasmosis, tuberculosis, rickettsiosis, syphilis, influenza and other acute respiratory diseases, enterovirus infection, acute lymphocytic choriomeningitis.

Treatment for West Nile Fever:

In the acute period of the disease, patients need bed rest. They are prescribed vitamins and other fortifying agents. With severe meningeal syndrome, repeated lumbar puncture and steroid hormone therapy are indicated. There is no specific treatment. Carry out pathogenetic and symptomatic therapy.

Forecast. The disease has a tendency to undulating course. There may be 1-2 relapses of the disease (with an interval of several days). The first wave is characterized most often by serous inflammation of the meninges, the second by heart damage, and the third by catarrhal phenomena. The course of the disease is benign. Despite prolonged asthenia in the period of convalescence, the recovery is complete. Residual effects and deaths are not observed.

Prevention of West Nile Fever:

The easiest and surest way to prevent West Nile is to avoid mosquito bites.
- When outdoors, use insect repellants that contain DEET (N,N-diethylmetaltoluamide). Follow the instructions on the packaging.
- Many mosquitoes are most active at dusk and dawn. Use insect repellant during this time, and wear long-sleeved clothing and trousers, or avoid going outside. Light-colored clothing will make it easier for you to spot mosquitoes.
- Good protective nets should be installed on windows and doors so that mosquitoes do not enter the house.
- Destroy mosquito breeding sites by keeping flower pots, buckets and barrels free of standing water. Change the water in pet water bowls and birdbaths every week. Drill holes in the tire swings to keep water out. Paddling pools should be drained of water and placed on their side when not in use.

Which doctors should you contact if you have West Nile Fever:

Are you worried about something? Do you want to know more detailed information about West Nile Fever, its causes, symptoms, treatment and prevention methods, course of the disease and diet after it? Or do you need an inspection? You can book an appointment with a doctor– clinic Eurolaboratory always at your service! The best doctors will examine you, study the external signs and help identify the disease by symptoms, advise you and provide the necessary assistance and make a diagnosis. you also can call a doctor at home. Clinic Eurolaboratory open for you around the clock.

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Phone of our clinic in Kyiv: (+38 044) 206-20-00 (multichannel). The secretary of the clinic will select a convenient day and hour for you to visit the doctor. Our coordinates and directions are indicated. Look in more detail about all the services of the clinic on her.

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You? You need to be very careful about your overall health. People don't pay enough attention disease symptoms and do not realize that these diseases can be life-threatening. There are many diseases that at first do not manifest themselves in our body, but in the end it turns out that, unfortunately, it is too late to treat them. Each disease has its own specific signs, characteristic external manifestations - the so-called disease symptoms. Identifying symptoms is the first step in diagnosing diseases in general. To do this, you just need to several times a year be examined by a doctor not only to prevent a terrible disease, but also to maintain a healthy spirit in the body and the body as a whole.

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For the first time, West Nile fever (WN) became known in the late 30s, when researchers were able to isolate the causative agent of this disease from the patient's blood. Subsequently, data began to appear on the widespread spread of this viral infection among the population of countries in Asia, South America and Africa.

According to statistics, outbreaks of this disease are especially common in many Mediterranean countries (in particular, in Egypt and Israel). Also in the medical literature, cases of detection of this viral infection in Indonesia, India and France (in Corsica and the Mediterranean coast) are described. Scientists managed to identify foci of this disease in Pakistan, Senegal, Turkmenistan, Moldova, Zaire, Algeria, Nigeria, Azerbaijan, Armenia, Sudan, Tajikistan, Kazakhstan, Ethiopia, Czech Republic, Romania, in Omsk, Volgograd, Astrakhan, Odessa region, etc. Such expansion of the nosoareal occurred at the end of the last century. Researchers attribute this spread of the disease from regions with a particularly hot climate to areas with moderate weather conditions to seasonal flights of wild birds, which are a reservoir of infection.

MN fever is a zooanthroponotic (that is, affecting both humans and animals) viral infection that is acute, transmissible (during bites by blood-sucking arthropods) and is accompanied by the occurrence of:

• fever;
• systemic lesions of the mucous membranes;
• serous inflammation of the membranes of the brain (sometimes up to meningoencephalitis);
• lymphadenopathy;
• in rare (up to 5%) cases, the appearance of a skin rash.

Not only humans, but also mammals can be exposed to infection. According to statistics, this disease is more often detected among people whose professions are related to agriculture, or rural residents. Also, an increased risk of infection is observed among hunters, fishermen and others who spend a lot of time in the favorite places of arthropods (for example, near water bodies).

As a rule, outbreaks of infection are observed in early spring or in the summer-autumn period. The peak incidence - more than 90% of all detected outbreaks - is recorded from July to October, when the number of blood-sucking insects reaches its maximum.

In the literature, you can find other names of the viral disease considered in this article:

• West Nile fever;
• encephalitis of the MN;
• duck fever.

In some cases, this infection can cause such life-threatening complications as cerebral edema, which can subsequently cause coma and death of the patient. Not only residents of endemic dangerous regions should know about it, but also tourists who are going to visit these geographical areas. You can get information about the causes, symptoms, methods for diagnosing and treating West Nile fever in this article.

Characteristics of the causative agent of infection and ways of its transmission

The development of MN fever is provoked by the invasion of the body of an RNA-containing flavovirus of group B. It has a spherical shape and dimensions of 20-30 nm.

The natural susceptibility to infection with the MN fever virus is high, and after the infection, those who have been ill develop intense or persistent immunity.

How the infection develops

After entering the bloodstream, the virus, along with its current, spreads throughout the body, causing systemic lesions:

• First of all, the lymphoid tissue suffers, and as a result, the patient has lymphadenopathy.
• If the pathogen penetrates through the blood-brain barrier, then the infected person may develop lesions of the substance and membranes of the brain (up to).

In some cases, infection leads to the death of the patient.

Symptoms

In some cases, after infection with the causative agent of MN fever, the patient does not experience any manifestations, while in others, the patient develops signs of this viral disease after 3-14 days (sometimes after 3 weeks). According to statistics and WHO, the asymptomatic course of this disease is observed in 80% of cases, and the manifest form of MN fever proceeds typically and with the development of violent symptoms.

With a manifest course, the disease manifests itself in two variants:

• without CNS lesions - accompanied by flu-like symptoms (sometimes with the addition of neurotoxicosis);
• with damage to the central nervous system - accompanied by meningeal or meningoencephalitic manifestations.

When clinical symptoms occur, signs of infection usually occur acutely, and a viral infection manifests itself as an increase in temperature to high numbers (38-40 ° C). The feverish period is accompanied by chills.

Often, before the onset of a fever, the following symptoms are felt:

• severe weakness;
• loss of appetite;
• a feeling of tension in the muscles (more often in the calf);
• headache.

The duration of the temperature rise is usually from 5 to 7 days (sometimes 1-2 days). MN fever is characterized by a relapsing course of the febrile period with periodic chills and heavy sweating.

In addition to fever, patients show signs of intoxication:

• frequent and strong, localized in the eye sockets and forehead;
• myalgia (especially intense in the neck and lower back);
• pain in the eyes;
• mild arthralgia without swelling of the skin over the articular joint.

At the peak of the development of intoxication syndrome, the patient has the following symptoms:

• recurring vomiting;
• unwillingness to eat;
• chest discomfort and heart pain;
• sensations of a sinking heart;
• drowsiness.

The skin of patients becomes hyperemic, about 5% of them develop small papular rashes. In rare cases, with a prolonged and undulating course of a febrile period, such elements of the rash can transform into hemorrhagic ones.

Almost all infected people show reddening of the conjunctiva and injection of the vessels of the eyeballs, and pain is felt when pressure is applied to the eyes.

Many patients have enlarged lymph nodes. As a rule, the following are involved in the pathological process:

• submandibular;
• lateral cervical;
• mandibular;
• cubital;
• axillary lymph nodes.

When probing, they are sensitive or slightly painful.

Sometimes infected people develop nasal congestion and a dry cough. When examining the oral cavity, graininess and redness of the mucous membranes of the hard and soft palate are revealed.

From the side of the heart and blood vessels, the following changes are detected:

• propensity to;
• muffled heart sounds;
• a rough systolic murmur heard at the apex of the heart (sometimes);
• on: focal disorders, manifestations of hypoxia of the heart muscle, slowing down of atrioventricular conduction.

On examination, the doctor may identify the following symptoms:

• thick coating of gray-white color on the tongue;
• dry tongue;
• diffuse pain when probing the anterior wall of the abdomen;
• moderate sensitivity and enlargement of organs determined by probing the spleen and liver;
• without pain in the abdomen.

With the penetration of the causative agent of the disease through the blood-brain barrier, which is observed in approximately 50% of cases, the patient develops the following signs of serous meningitis against the background of the above manifestations:

• increased tone of the muscles of the back of the head (that is, their rigidity);
• Kernig's symptom;
• Brudzinski's symptoms;
• signs of inflammatory processes in the CSF (lymphocytes up to 70-90%, pleocytosis up to 100-200 cells in 1 µl);
• horizontal nystagmus;
• asymmetry of the palpebral fissures (mild);
• decreased tendon reflexes;
• proboscis reflex;
• reduced muscle tone;
• absence of abdominal reflexes.

Encephalitic manifestations in MN fever are detected in very rare cases, but residual signs of asthenia of a mixed nature, manifested in weakness, increased sweating, memory impairment, sleep disturbances and mental depression, persist for a long time.

flu-like form

With this course of infection, signs of fever (for several days), weakness, pain in the eyes and chills are revealed. In some cases, patients complain of coughing and discomfort (itching, soreness) in the throat.

On examination, the following signs are determined:

• redness of the posterior surface of the pharynx and palatine arches;
• scleritis.

In some cases, there may be signs of indigestion:

• diarrhea;
• nausea;
• vomit;
• stomach ache;
• and not always).

Usually, the flu-like course occurs as a viral infection and is often accompanied by signs of meningism.

Neuroinfectious form

This form of the disease is observed in most clinical cases. With such a course of MN fever, the patient has the following symptoms:

• elevated temperature up to 38-40 ° C (for 7-10 days or several weeks), accompanied by chills;
• sweating;
• nausea and vomiting (up to 5 times a day), which is not associated with eating;
• headache;
• lower back pain (not always);
• myalgia (not always).

In more rare cases, symptoms of meningism, serous meningitis, and in extremely rare cases, meningoencephalitis are observed. After the improvement of the condition of patients, the following residual manifestations of a neurological nature persist for a long time:

• weakness;
• lethargy;
• memory impairment;
• sleep disorders.

Exanthematous form

This form of infection is extremely rare. On days 2-4, the patient develops elements of maculopapular (rarely roseola-like or scarlet-like) polymorphic exanthema. Against the background of these manifestations, there is:

• feverish state;
• catarrhal disorders;
• intoxication syndrome.

The rashes are eliminated after a few days and there is no pigmentation left on the skin after the rash. Often, with this form of MN fever, the patient's lymph nodes increase. They can be moderately painful when trying to probe or make movements.

The nature of the flow

According to the observations of specialists, this infection in 80% of cases is asymptomatic. Mild signs of virus damage occur in 20% of those infected. They usually have the following symptoms:

• headache;
• fever;
• vomit;
• nausea;
• enlarged lymph nodes;
• myalgia;
• rash on chest, back and abdomen.

As a rule, such manifestations of infection persist for several days.

A severe course of MN fever is extremely rare - out of about 150 seriously infected, only one person suffers a severe illness. These infected people show the following symptoms:

• high fever;
• stupor;
• headache;
• shiver;
• neck muscle stiffness;
• muscle weakness;
• convulsions;
• numbness;
• paralysis;
• loss of vision.

These signs of infection may last for several weeks. After that, the patient's manifestations of neurological consequences persist for a long time.

Possible Complications

The consequences of MN fever occur in most cases only with a neuroinfectious course of the disease. With the development of meningoencephalitis may develop:

• paralysis;
• paresis.

In rare cases, the infection leads to the death of the patient.

More often, the neuroinfectious course of this disease causes:

• swelling of brain tissue;
• disorders of cerebral circulation.

Diagnostics

When making a diagnosis, the doctor takes into account clinical, epidemiological and laboratory data. The following signs may indicate infection:

• acute onset;
• relatively short course of fever;
• systemic damage to mucous tissues, organs and lymph nodes;
• serous meningitis;
• stay in endemic dangerous regions and the fact of being bitten by a mosquito or tick.

To assess the patient's condition, the following studies are performed:

• - leukopenia;
• virological analysis to detect the MN fever virus (on culture media or on laboratory mice);
• enzyme-linked immunosorbent assay (ELISA);
• lumbar puncture followed by CSF sampling for analysis (it will show a slight increase in protein levels, pleocytosis).

To exclude an erroneous diagnosis, differential diagnosis is carried out with the following diseases:

• and other ORZ;
• acute lymphocytic choriomeningitis;
• listerellosis;
• tuberculosis;
• rickettsiosis.

Treatment

So far, scientists have not been able to develop drugs for the etiotropic treatment of MN fever. The patient is advised to stay in bed and take symptomatic drugs.

The incubation period for West Nile fever lasts from 2 days to 3 weeks, usually 3-8 days. Symptoms of West Nile fever begin acutely with an increase in body temperature up to 38-40 ° C, and sometimes even higher within a few hours. An increase in temperature is accompanied by severe chills, intense headache, pain in the eyeballs, sometimes vomiting, pain in the muscles, lower back, joints, and a sharp general weakness. The intoxication syndrome is expressed even in cases that occur with a short-term fever, and after normalization of temperature, asthenia persists for a long time. The most characteristic symptoms of West Nile fever caused by "old" strains of the virus, in addition to those listed, are scleritis, conjunctivitis, pharyngitis, polyadenopathy, rash, hepatolienal syndrome. Dyspeptic disorders (enteritis without pain syndrome) are not uncommon. CNS involvement in the form of meningitis and encephalitis is rare. In general, the course of the disease is benign.

The symptoms of West Nile fever caused by the "new" strains of the virus are significantly different from those described above. Yu.Ya. Vengerov and A.E. Platonov (2000) proposed a clinical classification of West Nile fever based on observations and serological studies. Subclinical infection is diagnosed during screening studies of the population by the presence of IgM antibodies or an increase in the titer of IgG class antibodies by four or more times. The flu-like form has no clinical specifics. It is the least studied, because often, due to the short duration of a health disorder, patients do not go to the doctor, or their disease is regarded at the clinic level as influenza, SARS.

Clinical classification of West Nile fever

In the flu-like form with neurotoxicosis, on the 3rd-5th day of illness, a sharp deterioration occurs, which is expressed by increased headache, nausea, vomiting, muscle tremor, ataxia, dizziness, and other symptoms of CNS damage. The fever in these cases is high, lasting 5-10 days. Specific clinical symptoms of West Nile fever - scleritis, conjunctivitis, diarrhea, rash - are observed in isolated cases. The symptoms of CNS damage dominate: intense headache of a diffuse nature, nausea, in half of the patients - vomiting. Frequent symptoms are dizziness, weakness, lethargy, radicular pain, skin hyperesthesia. More than half of the patients are diagnosed with meningeal syndrome, in some cases - an increase in blood pressure. In the study of cerebrospinal fluid, in addition to an increase in LD, there is no other pathology.

In patients with the meningeal form of the disease, the meningeal symptoms of West Nile fever increase within 2-3 days; the stiffness of the muscles of the neck is most pronounced. In comparison with the influenza-like form with neurotoxicosis, cerebral symptoms are also pronounced, transient focal symptoms are noted. The most characteristic are: stupor, muscle tremor, anisoreflexia, nystagmus, pyramidal signs.

During a lumbar puncture, clear or opalescent cerebrospinal fluid flows out under increased pressure. Cytosis varies widely - from 15 to 1000 cells per 1 μl (in most cases 200-300 cells per 1 μl) and is often mixed. In the study in the first 3-5 days of illness in some patients, neutrophilic cytosis (up to 90% of neutrophils). Mixed cytosis often persists up to 2-3 weeks. which, apparently, is associated with the presence of necrosis of a significant part of the neurocytes. This also explains the slower sanitation of the liquor, often delayed until the 3rd-4th week of the disease. The amount of protein is in the range of 0.45-1.0 g/l, the glucose content is at the upper limits of the norm or increased, sedimentary samples are weakly positive. The course of the disease is benign. duration of fever 12 days. meningeal symptoms regress within 3-10 days. After normalization of the temperature, weakness and increased fatigue persist.

The meningoencephalic form of West Nile fever is the most severe. The onset of the disease is stormy, hyperthermia and intoxication from the first days of the disease. The meningeal symptoms of West Nile fever are mild to moderate. From the 3-4th day, cerebral symptoms increase: confusion, agitation, delirium, stupor, in some cases turning into a coma. Convulsions, paresis of the cranial nerves, nystagmus are often noted, less often - paresis of the extremities, in the most severe cases, respiratory disorders and central hemodynamic disorders dominate. Lethality up to 50%. In recovered patients, paresis, muscle tremor, and prolonged asthenia often persist. Pleocytosis of the cerebrospinal fluid from 10 to 300 cells in 1 µl, the protein content reaches 0.6-2.0 g/l.

The blood picture in West Nile fever is characterized by features characteristic of severe viral infections: a tendency to leukocytosis, neutrophilia prevails, lymphopenia, and an increase in ESR are noted. Despite the absence of clinical symptoms, in the urine - proteinuria. cylindruria. leukocyturia.

Mortality among hospitalized patients is about 4-5%, which makes it possible to classify West Nile fever as a severe (dangerous) viral neuroinfection.

West Nile fever is an infectious disease that is caused by arboviruses and is transmitted by infected mosquitoes or ticks. However, the pathogenic organism can also be stored in the body of birds.

West Nile fever got its name due to the fact that it was originally distributed only in Africa, Asia and South America. Now the pathological process is not uncommon in countries with a hot and temperate climate.

The risk group includes people who are often in the habitat of arthropods: reservoirs, forests, swampy areas, shady areas.

West Nile fever has a nonspecific clinical presentation. First, the patient develops symptoms, which is rapidly aggravated - the temperature rises to 40 degrees, there is photophobia, the lymph nodes become inflamed.

The diagnostic program will include a physical examination, conducting the necessary range of laboratory tests. According to the results of diagnostic measures, the tactics of treatment will be determined.

In most cases, the prognosis is positive - recovery occurs without the development of complications. However, it should be taken into account that the clinic of the pathological process may be aggravated due to untimely or incorrect therapy. In this case, the risk of not only complications, but also death increases.

Etiology

In the vast majority of cases, fever is transmitted through the bite of an infected insect.

However, in some cases, the West Nile virus enters the human body in a different way:

• from an infected mother to a child;
• when transfusing infected blood;
• in organ transplantation;
• when using non-sterile medical instruments, as well as other devices in beauty salons, tattoo shops and similar institutions.

It should be noted that the above ways of transmission of infection are extremely rare.

Pathogenesis

West Nile fever enters the body of a blood-sucking insect along with the blood after it bites an infected bird. After that, the pathogen is concentrated in the salivary glands of the tick or mosquito itself, from where, when a person is bitten, it safely moves into the bloodstream.

After the virus enters the human blood, the clinic of the disease starts, that is, the initial symptoms develop, which rapidly worsens. In children, the clinical picture is always more severe than in adults, because the immune system is too weak at this age.

Classification

West Nile fever can occur in two clinical forms:

• asymptomatic - there is no clinical picture of the disease, there may be a slight and short-term deterioration in well-being;
• manifest - a typical clinical picture develops with pronounced and rapidly progressive symptoms.

The manifest form of the pathological process, in turn, can occur in two clinical variants:

• without damage to the central nervous system - the clinical picture is more similar to in severe form;
• with damage to the central nervous system - is characterized by a more severe course.

The last form of the clinic of the disease is divided into the following subspecies:

• meningeal;
• meningoencephalitic.

The two above forms of the development of the disease are characterized by extremely negative prognosis if treatment is not started in a timely manner. In this case, it is possible to develop not only severe, irreversible complications, but also death.

Symptoms

West Nile fever can occur in a latent or pronounced clinical form. The incubation period lasts up to three weeks, but most often 5–6 days. If there is a manifest form of the development of the pathological process, then the corresponding symptoms will appear in the future (or).

The symptoms of West Nile fever without CNS involvement are as follows:

• a sharp increase in temperature up to 40 degrees - the duration of the febrile state is 2-3 days, but in some cases it can last up to 12 days;
• Strong headache;
• chills, fever;
• increased sweating;
• pain in muscles and joints;
• photophobia;
• pain when rotating the eyeballs;
• inflammation of the lymph nodes, pain during their palpation;
• mucous membranes of the pharynx;
• weakness, drowsiness, feeling of weakness;
• polymorphic papular rash over the body, but such a symptom is not decisive, since it does not always occur.

If the central nervous system is involved in the pathological process, then the clinical picture will be characterized as follows:

• bouts of nausea and vomiting;
• neck stiffness;
• unsteadiness of gait, the patient's movements are uncertain;
• speech problems;
• symptoms of meningitis;
• headaches become unbearable, in their clinic they are more like seizures;
• body temperature rises to critical limits;
• disturbance of consciousness;
• generalized seizures.

With such a clinical picture, the patient's condition is characterized as extremely serious, since there is a high risk of developing complications that can cause death.

Diagnostics

The diagnostic program in this case should be carried out comprehensively, since if the central nervous system is affected, differentiation with meningitis will be required. In addition, the diagnosis can be complicated by the non-specificity of the clinical picture.

First of all, a physical examination of the patient is carried out, a personal history is taken, and the current clinical picture is clarified.

Then the following activities are carried out:

• polymerase chain reaction, PCR test;
• carrying out enzyme-linked immunosorbent assay (ELISA test);
• general and detailed biochemical blood test;
• serological blood test;
• virological study to identify the pathogen;
• lumbar puncture of the cerebrospinal fluid.

Instrumental diagnostics, as a rule, is not carried out, but in some cases CT or MRI of the brain may be needed if meningitis develops against the background of the current pathological process. In this case, a comprehensive and thorough diagnosis and treatment are two interrelated factors, since specific therapeutic measures are impossible without an accurate diagnosis.

Treatment

Therapeutic measures for this disease are conservative.

The patient after hospitalization is prescribed the following drugs:

• interferon inducers;
• glucocorticosteroid;
• diuretics;
• antipyretic;
• inhalation of humidified oxygen;
• anticonvulsants;
• broad-spectrum antibiotics;
• antioxidants;
• sedatives;
• to improve cerebral circulation;
• vitamin and mineral complexes.

Detoxification therapy is also additionally prescribed, measures are taken to stabilize the water and electrolyte balance.

If the pathological process passes without meningitis, then the prognosis is favorable - recovery occurs in 100% of cases and without the development of complications.

Possible Complications

Possible complications include:

• acute cerebrovascular accident.

Lethal outcome is not excluded. Self-medication in this case is excluded, and if symptoms occur, you should immediately seek medical help.

West Nile fever is a zoonotic viral disease (capable of infecting animals and humans). The disease is very serious and severe. With this disease, there is a sharp increase in temperature, the development of meningoencephalitis and inflammation of the mucous membranes. The causative agent of the disease enters the human body with a mosquito or tick bite. West Nile fever is common in rural areas, its range is quite extensive. The centers of fever are found in the countries of Africa and Asia, the Mediterranean and in the territory of the former USSR. Outbreaks of the disease are recorded in the summer-autumn period, when the activity of blood-sucking insects is maximum. The disease affects adults and children.

Unfortunately, there is no effective therapy for the disease, since traditional antiviral drugs do not always successfully suppress the infection. Apply mainly symptomatic and immunomodulatory treatment. There are folk remedies that will reduce the symptoms of the disease and alleviate the condition of the patient, as well as strengthen the body and help in the fight against infection.

Causes of the disease

West Nile fever is an infectious disease caused by an RNA-containing flavivirus. This virus is carried by blood-sucking insects. The source of infection is sick animals and birds, both domestic and wild.

Although the disease is transmitted through blood, the chance of infection during medical procedures is minimal. In the course of a standard test, donated blood is tested for a number of infections, including the presence of West Nile virus.

Development of a fever

The virus enters the human body and spreads with the blood to various organs and tissues. After infection, the incubation period begins - the latent phase, during which the virus is present in the body, but the symptoms of the disease do not appear. The incubation period lasts from several days to three weeks.

During the development of fever, the virus infects the lymphoid tissue. Also, the causative agent of the disease can penetrate the blood-brain barrier and infect the cells of the meninges. In this case, the patient develops meningoencephalitis, which is manifested by neurological symptoms.

The fever can last from several days to several weeks. Gradually, the titer (amount) of the virus falls, the patient's condition improves. Neurological symptoms also disappear. Weakness and residual neurological effects (memory impairment, depression) may persist for a long time.

After a person recovers, he develops immunity. However, immunity is not stable and protects only against a specific strain of the virus. A recovered person can become ill again if they become infected with a different strain of the virus.

Most often, the disease affects young people, but it can also develop in the elderly. In this case, the disease is especially dangerous and difficult to treat. The number of infected increases in summer and early autumn, when the activity of blood-sucking insect vectors peaks.

Symptoms of the disease

After the incubation period, an infectious process develops. The disease begins acutely, with fever. The body temperature of a person rises to 38–40 ° C, the patient feels chills.

In some cases, before the onset of fever, there is a short-term feeling of weakness, loss of strength, loss of appetite. There are also signs of intoxication of the body: muscle weakness, excessive sweating,. In other patients, fever is not preceded by any symptoms.

The elevated temperature lasts from 1-2 days to a week. The patient develops signs of intoxication:

• headache, which is most often localized in the frontal lobe;
• Pain in the eyes;
• muscle pain, especially in the neck and back;
• aches in the joints;
• nausea, vomiting;
• lack of appetite;
• pain in the heart against the background of damage to the toxins of the heart muscle;
• increased sleepiness.

The patient's skin is hyperemic. Occasionally, a small rash occurs on the skin. With prolonged fever, the rash can become hemorrhagic in nature - hemorrhages occur.

Redness develops on the mucous membrane of the eyelids and mouth. In some cases, the patient is worried about a runny nose and cough without sputum. Another symptom of West Nile fever is a gray coated tongue with dry mucous.

With the development of infection, an increase in peripheral lymph nodes is observed. The patient experiences pain during their palpation.

There is damage to the cardiovascular system. Patients with West Nile fever are characterized by a decrease in blood pressure and disruption of the heart muscle. Heart sounds are muffled. If an electrocardiogram is performed, then a lack of oxygen supply to the heart is detected.

In most patients, lung tissue is not affected, although less than 1% of patients may develop.

Pathological changes also affect other internal organs. Observe the deterioration of the intestines: constipation, occasionally - diarrhea. An increase and disruption of the normal functioning of the liver and spleen are observed.

With the development of meningoencephalitis and damage to the cells of the meninges of the brain, the patient develops neurological symptoms:

• (voluntary movement of the eyeballs in the horizontal plane);
• unequal size of the palpebral fissures;
• decreased muscle tone and tendon reflexes;
• lack of abdominal reflexes;
• the proboscis reflex and the palmo-chin reflex are reflexes of newborns that do not normally occur in adults;
• insomnia;
• depression;
• memory impairment;
• some patients also have hallucinations, tremors, anxiety increases, their behavior becomes inadequate;
• in severe cases, cerebral edema occurs, cerebral bleeding is disturbed, which leads to loss of sensitivity, the development of paresis and paralysis.

Disease classification

There are several forms of West Nile fever.

1. Neuroinfectious - the most common form.
   The patient develops an acute fever, and the membranes of the brain are affected. This type of fever is characterized by neurological symptoms. The patient may experience hallucinations, anxiety increases, he is tormented by insomnia. Residual neurological symptoms persist long after recovery.
2. Flu-like shape.
   It is characterized by the predominance of general symptoms of the infectious process and intoxication: weakness, chills, fever, pain in the muscles, joints and eyes. Sometimes conjunctivitis develops, sore throat, patients suffer from cough. Damage to the organs of the digestive system also occurs: nausea, vomiting, diarrhea occur. The liver and spleen are often enlarged.
3. Exanthematous - a fairly rare form of the disease.
   A few days after the onset of the disease, an exanthema appears on the patient's skin - a rash of a maculopapular, scarlet-like or roseol-like nature. In addition to the rash, the patient develops characteristic symptoms of intoxication and signs of damage to the nervous system. The rash disappears after a few days, leaving no traces of it.

Diagnosis of the disease

West Nile fever is diagnosed based on the history, clinical manifestations, and laboratory blood tests. Also, the diagnosis takes into account the patient's residence or visit to areas where fever is common, the presence of tick bites and mosquito bites.

In the case of characteristic symptoms, the patient's blood is checked for the presence of antibodies against the febrile virus. However, this diagnosis may be inaccurate. There is a high risk of a false positive result as all flaviviruses are similar. Another virus may be circulating in the human body against which antibodies are produced, and these antibodies will show a positive reaction in the serological diagnosis for the West Nile virus. For accurate diagnosis, the pathogen is isolated from the patient's blood and infected laboratory animals.

Treatment of the disease

The effectiveness of antiviral drugs in West Nile fever is questionable. Therefore, symptomatic treatment is used. And the suppression of the reproduction of the virus and its elimination are carried out by the human body's own defenses.

In the treatment of the disease, bed rest is indicated. Important in therapy and nutrition. The patient should receive a sufficient amount of vitamins that increase the body's resistance. Food should be lean and easy to digest. It is better to give preference to boiled vegetarian food.

Traditional medicine offers a number of remedies that will help relieve the symptoms of fever, have an antiviral and immunomodulatory effect. This treatment is safe for health and has no side effects.

Medicines for fever

1. Periwinkle. A decoction of periwinkle herb reduces body temperature, has an antispasmodic effect and reduces pain during fever. In one glass of water, steam 1 tbsp. l. crushed leaves of this plant. Boil over low heat for 20 minutes, then insist an hour and filter. Drink 1/3 cup 3 times a day.
2. Willow bark. A decoction of willow bark reduces body temperature during fever. In 300 ml of boiling water, steam 1 tsp. crushed bark, boil over low heat until the volume of liquid is reduced to 250 ml. Drink the whole decoction once a day before meals. Honey can be added to taste.
3. Lilac. 20 fresh leaves of this plant are cut and poured with 200 ml of boiling water, infused for 2 hours, then filtered. Take half a glass of infusion 2 times a day.
4. Hop. Hop cones are crushed. 2 tbsp. l. vegetable raw materials are poured into 400 ml of boiling water, infused for 2 hours, then filtered. Take ¼ cup twice a day.
5. Herbal tincture. Mix 2 g of wormwood color and 20 fresh lilac leaves, add 1 g of eucalyptus oil and pour all 1 liter of vodka. Insist in glassware for two weeks in a place protected from light. Shake daily. Take 30 ml of the drug 2-3 times a day.

Immunomodulating agents

Forecast

West Nile fever is a serious disease. Like other viral infections, it shows the ability to relapse. It is very difficult to completely remove viral particles from the body, they can remain in an inactive form inside human cells. There may be 2-3 recurrences of fever.

In general, the prognosis is favorable. Despite the severe and prolonged course, in most cases there is a complete recovery. The effects of fever can persist for a long time, but they also pass with time. A person does not experience irreversible changes.

Prevention

In the case of living or visiting regions where the disease is common, it is recommended to use protective equipment against mosquitoes and ticks. It is better to limit exposure to fresh air in the evening and at night, wear long sleeves, use repellents. It is also necessary to protect housing from insects, use mosquito nets on windows.

There are no other methods of prevention. However, the disease will be easier, and recovery will come faster in people with strong immunity. Therefore, it is recommended to strengthen health: eat well and eat fresh vegetables, fruits and berries, play sports, harden.