Nipah virus and Hendra virus infection
First, the pathogenic characteristics
Two viruses are named after place names, were analyzed by electron, serology and DNA analysis, the proof that its subjects are paramyxovirus (Paramyxoviridae), but because the virus characteristics and the division between the known virus, too, so attributed to the virus is shed, the Nipah virus, Hendra (Henipahvirus), as a polymorphism with the envelope membrane of the virus, negative strand genome linear single-stranded RNA, both fluid and tissue through the dissemination of and cause lethal zoonotic infection. Hendra virus (Hendra virus; HeV) genome length of approximately 18,234 nt, the size from 38 nm-600 or above range. Nipah virus (Nipah virus; NPV) similar appearance to HeV, the size of about 200-300 nm or more. Immunofluorescence assay, NPV and HeV will produce cross-reactive antibodies. In terms of analysis and comparison of nucleotide sequences, both about 20% of the nucleic acid sequence differences.
Hendra virus infection in the earliest reports occurred in September 1994 in the east coast of Australia Queensland Province (Queensland) Brisbane, the capital (Brisbane) suburb of Hendra (Hendra), currently only in the Australian native, has not reports spread to other countries. Horse and human disease can cause fatal respiratory diseases, human infection is mainly due to contact with sick horses caused by the organization or body fluids. Patients can detox their urine, in addition to the virus from the sick horses will not be carried in respiratory droplets, nor force of highly infected patients. Ma and Ma will not cause or spread among people, wildlife in the epidemiology may serve in a role.
Nipah virus occurred from October 1998 began, the succession in the northern Perak, Malaysia Ipoh (Ipoh) region, there pig farmers or had close contact with the pigs who caused the deaths occurred even in the case of encephalitis. Most of the pig and the patient or close contact with pigs, and its spread is also nothing more than contact with sick animals caused by the organization or body fluids. Dogs, cats, horses also susceptible. 1998-1999, Singapore, Malaysia, the infection may cause meningoencephalitis 265, 105 people died. Nipah virus since 2001, since a number of encephalitis cases occur in Bangladesh (Bangladesh), especially the 34 cases occurred in March 2004 Cluster infection, 24 cases of death caused by the most serious.
Third,harbor the virus
Fox bat (flying fox) is the natural reservoir of these two diseases and carriers. The distribution of bats in Australia, Indonesia, Malaysia, the Philippines, and nearby islands to eat the fruit. How transmission of the virus to bats pigs, is unclear. Hendra virus can infect humans and horses, cats can be infected by artificial, but the dog, mouse, rat and chicken with resistance. Nipah virus can still infect other than pigs, dogs, cats and horses.
Fourth, clinical diagnosis and differential
Latency between 4 and 18 days, a large epidemic in Malaysia, most of the patients (93 / 94), two weeks ago in the pathogenesis of contact with pigs. The average age of these patients was 37 years, male to female ratio of 4.5 to 1. In many cases, asymptomatic infection. In symptomatic cases, the disease usually “class legislation flu” symptoms present, patients have high fever, headache, dizziness, vomiting and muscle pain. Disease can progress to drowsiness, unconsciousness, convulsions and coma, encephalitis and other symptoms. Symptoms include more special myoclonus (segmental myoclonus), loss of reflexes (areflexia), low muscle tone (hypotonia), high blood pressure and heart rate, these symptoms show the brain stem and upper cervical spinal cord have been violated. If not normal Doll’s eye sign and heart rate, then a poor prognosis. Clinically obvious symptoms of patients, 50% will die. Among the 64 survivors, 12 patients relapsed, but these patients within one year of onset were not exposed to infected pigs, and its recurrence can be a very long incubation period can be very short, but the progress of neurological symptoms but soon . In some ways, the Nipah virus encephalitis cases caused by delayed, and the measles virus cause subacute sclerosing pan-encephalitis (subacute sclerosing panencephalitis, SSPE) like, both to the early symptoms of encephalitis are not the main However, neurological symptoms appear later. And stained SSPE phase ratio, some of Nipah virus encephalitis of patients with delayed recovery, but long-term prognosis have to be observed. The symptoms caused by Hendra virus, places respiratory tract, causing only a case of meningoencephalitis.
Fifth, laboratory and other tests
Hendra virus infection may be by histopathological examination, virus isolation, ELISA, immunohistochemistry staining, VN detection antibody, electron microscopy and PCR, for diagnosis. Nipah virus can make use of virus isolation, PCR and IHC, etc. diagnosis. Virus isolation in Vero cells can be part of the cerebrospinal fluid from patients develop isolated and Vero cell lines induced a strong cytopathic effect plaque of cell fusion. IHC can be used in the monoclonal antibody portion of brain, kidney and lung and other tissues after the positive. Part in the serological examination, most patients can be detected against the Nipah virus IgM antibodies, while a few of which have IgG antibodies.
Sixth, treatment and prognosis
Nipah virus infection in the treatment process, no drug has been proven effective. Treatment focuses on providing effective supportive therapy. Antiviral drug Ribavirin is a broad spectrum of viral suppression drugs, for respiratory syncytial virus (respiratory syncyticial virus), influenza, and measles (measles) virus is a range of other effects. There is some evidence that the use of Ribavirin treatment as soon as possible, to reduce the time of fever and disease severity. However, while Ribavirin in a study, has no significant side effects, but to cure disease or improve survival, the effect still need further study.
Seventh, prevention and infection control
Human Nipah infection in pigs with respiratory secretions or by direct or indirect contact with the organization come. No cases of human infection. And pigs to prevent any direct or indirect contact is the most secure. (A) does not contact the protective equipment, should observe the fourteen days. (B) Although no human infections, but patients should be the standard contact isolation. (C) contact with sick pigs and pigs, and pigs, the whole destruction.