Nipah virus is a pathogen that causes an infectious disease with a wide range of symptoms. It is possible that there are no clinical manifestations, as well as signs of respiratory infection or brain damage. Encephalitis is especially often registered. Diagnostic methods used to isolate the virus and antibodies to it are PCR, isolation of the virus in cell culture and ELISA, while the clinical picture and epidemiological history are extremely important. Etiotropic treatment for the elimination of the pathogen has not been developed, measures of pathogenetic, symptomatic effects are used in therapy.
ICD 10
B33.8 Other specified viral diseases
General information
Nipah virus causes a disease (viral encephalitis Nipah, viral infection Nipah), which is zooanthroponism: the pathogen can be transmitted to humans from a sick animal or human. The infection became known for the first time in 1999, when an outbreak occurred in Malaysia, the pathogenic microorganism itself was isolated in Bangladesh (2001). The pathology is most common in India, Thailand, Cambodia, also in the Philippines, Madagascar, and Ghana. Livestock regions are most often affected. The seasonality of the disease is year-round. There were no differences in morbidity between the sexes and different age groups.
Causes
The causative agent of infection is the Nipah virus. This pathogen belongs to the paramyxovirus family. Natural reservoirs are carnivorous bats, mainly of the genus Pteropodia, domestic pigs, less often horses. The path of infection is usually contact (when cutting carcasses, caring for animals), as well as airborne (between humans, animals and humans). Asian outbreaks occurred due to the alimentary transmission pathway.
Risk factors
A high risk of infection accompanies professions such as medical workers, fruit pickers, cooks. The main risk factors are:
- eating fruits, vegetables, fresh date palm juice contaminated with saliva, urine, feces of the natural hosts of the virus;
- work in the pig industry, veterinary medicine;
- tourist trips in areas with low sanitary and hygienic control.
Pathogenesis
The main targets of the Nipah virus are bronchial epithelium and type II pneumocytes, as a result of which inflammatory cytokines are induced, symptoms of acute respiratory distress syndrome occur. The virus can enter the bloodstream with subsequent dissemination, free or bound to leukocytes. In addition to the lungs and brain, the spleen and kidneys can act as target organs. Generalization of infection leads to multiple organ failure.
Penetration of the Nipah virus into the central nervous system is possible hematogenically (through the vascular plexus or vessels of the brain) and / or through the cranial nerves. Several experimental animal models have shown that the pathogen can directly penetrate the brain tissue through the olfactory nerve. The viral infection subsequently spreads through the cruciform plate, the olfactory bulb and further throughout the ventral cortex.
Nipah virus symptoms
The incubation period is from 4 to 45 days, on average, about two weeks. The disease begins acutely, includes symptoms of severe intoxication: weakness, nausea, decreased performance, an increase in body temperature over 38 ° C with chills. Many patients mention dizziness, repeated vomiting with a fountain at the height of a headache, which does not bring relief. Sometimes there are sore throats.
The symptoms of the disease are progressing, others note pronounced drowsiness, lethargy, monosyllabic answers of the patient to questions. Then there are paralysis or paresis of the limbs, manifested by a decrease in strength in the arms and legs, the inability of active movements. The patient cannot move independently, hallucinations and delusions develop.
Often, the absence of neurological complaints brings to the fore the defeat of the respiratory apparatus. Symptoms of respiratory insufficiency gradually increase, and therefore patients complain of shortness of breath, take a forced position with support on their hands. Breathing becomes noisy, whistling, intercostal spaces are drawn in, the skin of the face and chest turns purple.
Complications
The Nipah virus affects the nervous and respiratory tissues, so the most frequent complications are acute respiratory failure and neurological consequences (in 20% of infected people). Often, after recovery, paralytic disorders, symptoms of mental personality disorders, memory loss, cognitive dysfunction may persist.
Diagnostics
Diagnosis of infection caused by the Nipah virus is more often carried out by infectious diseases doctors. It is important to carefully collect an epidemiological history, especially with regard to visits to areas endemic to the disease. The main laboratory-instrumental and clinical symptoms of the disease:
- Physical data. An objective examination reveals fever, symptoms of paresis, paralysis of cranial nerves, less often meningeal signs, convulsions, cerebral manifestations. Lung damage occurs with shortness of breath, decreased saturation, forced position of the patient, with auscultation there may be wheezing, weakening of breathing.
- Laboratory tests. In the blood test, leukocytosis, moderate eosinophilia, and a slight acceleration of ESR are detected. In biochemical parameters, an increase in the activity of acute-phase proteins is possible.
- Identification of infectious agents. Detection of the desired virus is carried out by real-time PCR, less often by isolation in cell culture. It is possible to determine the titer of antibodies to the pathogen in ELISA.
- Instrumental methods. According to the indications, X-ray of the chest and skull bones, CT or MRI of the brain, lungs, ultrasound examination of the abdominal cavity, kidneys are performed.
Differential diagnosis
The Nipah virus causes a variety of symptoms similar to those in many pathologies. This includes viral encephalitis, the causative agents of which are tick-borne encephalitis viruses, herpes, rubella. In addition to the defeat of the central nervous system, skin manifestations occur with these infections, there is a certain anamnesis. Pneumonia of bacterial, viral or mixed etiology clinically differ little from each other, while the diagnosis is established in the laboratory.
Nipah virus treatment
There are currently no standardized protocols for the management of patients infected with the Nipah virus. Inpatient treatment is recommended for clinical and epidemiological indications, for patients at risk. Resuscitation is often needed. There are no dietary restrictions. Most often, patients are prescribed bed rest or semi-bed rest.
Conservative therapy
Treatment of Nipah viral infection is usually symptomatic and pathogenetic. Vital functions, water-electrolyte balance, adequate blood circulation and blood gas composition are most often supported. If artificial ventilation is necessary, only mechanical invasive methods are recommended (in order to avoid the spread of infection).
Ribavirin has shown efficacy in in vitro experiments, clinical efficacy against the Nipah virus has not been proven. At the same time, some researchers offer this medicine as the drug of choice in patients with a confirmed diagnosis. Chloroquine is also active against the pathogen only in an isolated cell line. Treatment with acyclovir has been described, but no qualitative studies have been conducted.
The Japanese licensed direct-acting antiviral drug favipiravir, which effectively relieves flu symptoms, actively suppresses the reproduction of the Nipah virus, but exclusively in hamster models, as well as the proposed natural Ephrin-B2 ligands. Treatment with other antiviral drugs is not recommended. Antibiotics are not indicated without a confirmed secondary bacterial infection.
Experimental treatment
The monoclonal antibody m102.4, developed for the prevention and treatment of pathology caused by the Nipah virus, successfully passed the first phase of clinical trials in 2020. No deaths or serious side effects were recorded. The researchers claim that the early administration of this drug is much more effective, so the niche of application is supposed to be preventive treatment for contact persons.
Prognosis and prevention
The prognosis is favorable with early detection and uncomplicated course. Mortality in the disease caused by the Nipah virus reaches 40-75%. No specific preventive measures (vaccines) have been developed. Non–specific measures – food hygiene, hand washing, refusal to travel to endemic areas. Those who care for the sick need to wear masks and gloves.
Regular, controlled disinfection of livestock farms, especially pig farms, meat processing plants, is important. Fruits, vegetables, food products should not have traces of bites, urine and feces of bats. Medical workers are required to wear protective suits, respirators, strictly adhere to safety regulations, asepsis, antiseptics.