West Nile Fever - Causes, Symptoms and Treatment .MF .

August 12, 2017 17:52 | Infectious Diseases

West Nile fever - an acute viral disease zooantroponoznoe prirodnoochagovyh with transmissible mechanism of transmission, characterized poliadenopatiey, erythema and inflammation of meningeal taking place against the backdrop of feverish intoxication syndrome.

first epidemic outbreak was registered in 1937 in the study of Japanese encephalitis.In the middle of the XX century it was registered another epidvspyshka in Africa and Asia, and later in the Mediterranean countries (especially Israel and Egypt), the southern part of Russia, Belarus, Ukraine, Romania, Czech Republic and Italy.It was subsequently conducted a serological study confirming the presence of antibodies to the virus - in Krasnodar, Omsk and Volgograd regions, Belarus, Azerbaijan, Tajikistan and Ukraine - these studies raise the question of endemic areas and confirm the transfer of the disease, even in the obliterated / subclinicalform.The relevance of this disease has increased in 1999-2003, when the incidence has been increasing in Ast

rakhan, Volgograd and Krasnodar Territory.

Pathogen West Nile

RNA virus belonging to the family Togaviridae, genus flavovirusov - on the basis of the specific accessory can understand the structure of the pathogen, which explains the clinical picture:

• Have capsular protein protects against phagocytosis;
• The presence of spines which include glycoprotein E1 with hemagglutinating activity (ie, the process of adhesion of red blood cells and their subsequent deposition on vascular surfaces) - it explains hyperemia (redness) of the face and mucous membranes of the oral cavity including the hard palate, vascular injection sclera.
• The presence of soluble antigen having type-specific activity in organs CMF (system monocytic phagocytes - histiocytes connective tissue, Kupffer cells of the liver (stellate retikuloendoteliotsity), alveolar macrophages lung macrophages of the lymph nodes, spleen, bone marrow, pleural and peritoneal macrophages, osteoclasts in bone tissue, microglia nerve tissue synoviocytes of synovial membranes, skin cells Langergaisa, amelanotic granular dendrocytes).
• Fast genetic variation - this feature plays an important role in the creation of the protein shell, responsible for the antigenic properties and the interaction with the body's cells.Due to the high genetic variability of the sum sad predictive picture - the more perfect the virus, the more severe complications it causes, this fact is based on the scientific observation: the old strains of West Nile allocated up to 1990 - do not cause severe CNS lesions, but all other epidemicflash registered at a later date associated with the mass disorders and severe CNS lesions.

virus Stability:

• Unstable at room temperature;
• There remains at a temperature «-70 ° C";
• inactivated ether and deoxycholate-Na;
• Dies at 56 ° C for 30 minutes.

susceptibility is high and depends on geographical location: so in hyperendemic areas (eg Egypt) sick young children and in the centers with low prevalence often ill adults.By maloendemichnym areas include the Volgograd and Astrakhan regions, Krasnodar and Stavropol Territory.Genital no restrictions.The prevalence almost everywhere, as the disease was registered on every continent, but with varying intensity.Seasonality due to the activity of the mosquito vectors and it is connected with two types of cycles: rural (when mosquitoes are active ornithocophilous, ie those that feed on birds) and urban (part synanthropic mosquitoes, ie, feeding both birds and humans), so the season is the end of July and the beginning of the cold weather.

Causes of infection with West Nile fever

source and reservoir (guardian) - birds of water and near-water complex, a carrier - the mosquitoes.Ways of infection - transmissive (ie, through the mosquito bite).

Symptoms of West Nile

The incubation period - the time from the beginning of the introduction of the pathogen, before the first clinical symptoms and, in this case it lasts 3-8 days on average, but may last up to 3 weeks.During this period, the pathogen passes its way from the bite of a mosquito, further propagation of the pathogen at the site of the bite, developing further the primary bacteremia and replication in the endothelium of blood vessels and organs of the CMF (monocytic phagocytes system - all that relates to these bodies described above).

Once the pathogen reaches a certain concentration, and comes out with these target organs, where there was a proliferation of primary replication occurs secondary bacteraemia and it marks the beginning of the visible symptoms.The period of clinical manifestations - as soon as the starting secondary bacteraemia, there is an acute onset with rise of temperature up to 38,5-40 ° C, and it is increased for several hours, accompanied obscheintoksikatsionnymi symptoms as: fever, headache often localized in the forehead, paineyeballs, vomiting, generalized myalgia (muscle pain is especially pronounced in the neck and lower back), arthralgia (joint pain) and general malaise.

Appearance patient resembles haemorrhagic fever - facial flushing, conjunctivitis, vascular injection sclera, redness and grain mucous cheeks and hard palate.A further step of symptoms will depend on the kind of damaging strain (but in any case, the most commonly affected following target organs: liver, brain, kidneys):

• With the defeat of the "old" strains (ie, those that have been distributed to 90ies) arises: scleritis, conjunctivitis, pharyngitis, poliadenopatiya, rash, Banti's syndrome, dyspepsia.But these strains for benign.
• When infecting "new strains of" further picture of the development can be a little sad, and with the clinical manifestations of more variable and associated with various forms of the disease:
- In subclinical form no clinical manifestations no diagnosis is possible only by means of a screening study - determinationIgM or IgG titer increase of 4 or more.
- flu-like shape of the least studied, because people often do not seek medical attention because of non-specific symptoms, referring to the common cold.But as soon as the general condition worsens, the previous symptoms is no links.In this form of deterioration recorded 3-5 days and is manifested in the form of strengthening of headache, of nausea and vomiting, tremor, ataxia, dizziness, radicular pain, skin hypersensitivity, meningivlnye symptoms, prolonged fever - high temperature stable, which holds about 10days.This syndrome is characterized more for new strains.
- meningeal form is characterized by access to the first brain symptoms (headache, dizziness, confusion, vomiting, not bringing relief, muscle tremor), to the hospital and joins focal symptoms - anizorefleksiya, nystagmus, pyramidal signs.
- Meningoentsefalnaya form - the most severe form of the disease, because cerebral symptoms occur more pronounced with the gradual increase: confusion, agitation, delirium, stupor often goes into a coma.Also, last but not least focal symptoms: convulsions, paresis of cranial nerves, nystagmus, paresis of limbs, breathing disorders, central hemodynamic disturbances.In this form of mortality reaches 50%, while the recovered register frequent complications in the form of paresis, muscle tremors and prolonged fatigue.

Diagnosing West Nile

Diagnosis is based primarily on epidemiological data - are considering a stay in endemic areas, there are cases of influenza-like illness or neuroinfections in July-October and, in addition, try to carry out serological diagnosis.Just collect the history of mosquito bites, the exits of the city, the availability of housing near open bodies of water.

Lumbar puncture - the main and often the only indication for its conduct are positive meningeal symptoms.When WNV in cerebrospinal fluid (lumbar) there are specific changes characteristic of certain forms of the disease: in the form of influenza - only increases the pressure of cerebrospinal fluid and everything;with meningeal form - also increased pressure, cell count ranges from 15-1000 cells in 1 mm, but usually 200-300, often mixed.Often in the first 3-5 days of neutrophil cell count character - ie, in the cerebrospinal fluid is dominated by neutrophils, and attributed this to the fact that there is a significant part of the death of neurons.For the same reason disrupted sanitation liquor.Also in this form recorded increasing protein (0.45-1.0 g / l) and glucose (upper limit of normal and higher).

KLA (CBC) in the incubation period or the beginning of clinical manifestations - ↓ A ^ (leukopenia), and in the midst of clinical manifestations - ↑ A ^ (leukocytosis), NF and ESR, ↓ Lf (lymphopenia).

OAM - proteinuria (protein in the urine), cylindruria (presence of columnar epithelium in the urine), leucocyturia (white blood cells in the urine).

serological diagnostic methods: HAI (hemagglutination inhibition reaction), RSC (complement fixation test), pH (neutralization reaction), ELISA (enzyme-linked immunosorbent assay);Using pH RNGA and looking at the increase in antibody titer in paired sera at time intervals of 10 days.RAC - designed to detect antibodies antigenneytralizuyuschih and, with a positive result, talk about the last stages of the disease, or the recently adjourned.IFA - is aimed at the detection of specific antibodies - IgG (indicate on the already transferred a disease or the completion of infection) and IgM (talking about the height of the disease).Serologic methods advantageously carried out up to 7 days from the onset of the disease (ie, since the clinical manifestations), and after 2-3 weeks from the time of the first trial.

genetic method - PCR (polymerase chain reaction) is aimed at the detection of the genetic material of the pathogen.With this method, you can take the study plasma, serum and cerebrospinal fluid.

Treating West Nile

Tk all viral diseases are treated virioidnymi drugs, the West Nile fever is not an exception, but none of the antiviral drugs did not give the expected result, and at the moment treatment is limited to the relief of symptoms:

1) at a high intracranial pressure - furosemide or potassium veroshpiron drugs (it acts more slowly compared with furosemide, but a potassium-saving).
2) If the brain edema - mannitol, followed by administration of furosemide.If cerebral edema rapidly progressive, additionally prescribed dexamethasone.
3) fluid volume compensation - administered by intravenous infusion polyionic solutions (Trisol) and colloid solutions (albumin, reopoligljukin) - 2: 1
4) In order to combat hypoxia administered oxygen inhalation and transferred to the ventilator for the following indications:
• breathlessness (frequencybreathing is increased by 2-fold or more of the norm);
• hypoxia (à la carte O₂ pressure of & lt; 70 mm Hg);
• hypocapnia (SO₂ pressure of & lt; 25 mm Hg);
• hypercapnia (SO₂ & gt; 45 mm Hg), generalized convulsions or coma.
5) In convulsions prescribed Relanium (seduksen)
6) Sedatives and antioxidants
7) Means improving brain blood flow (pentoksifelin)
8) Antibiotic treatment in secondary bacterial infections, and prescribe a balanced enteral-parenteral nutrition, vitamins and trace elements.

treatment duration is an average of 10 days, with complications of the nervous system - up to 30 days and only on the expiration of these terms carry an extract of patients (including normal temperature and regress of neurological symptoms).After discharge from the hospital dispensary observation neurologist prescribed to full rehabilitation and regress of neurological symptoms.

complications of West Nile

Complications occur mainly from the central and peripheral nervous system - and obschenevrologicheskie focal symptoms.

Prevention Prevention mostly non-specific and aimed at reducing the number of mosquitoes, which is achieved by carrying out treatments mosquito breeding sites of mosquitoes in town and in the surrounding areas and areas of rest.Disinfestation subjected basements of apartment houses and public buildings in urban and rural areas.Consider an artificial reduction in commensal populations of birds (crows, pigeons, sparrows, etc).During the period of seasonality used clothing protects against mosquito bites, minimizing the time spent outdoors.

Medical consultation

Question: Does a sick person is dangerous to others?
answer is no, but it is a potential threat if there are mosquitoes near

Question: Does immunity is formed after suffering the disease?
answer is yes, but it is strictly specific to a particular strain and short.

therapists Shabanova I.E