United States is now being hit by the disaster caused by the West Nile virus. The virus was first track of his legs in the country in August 1999, in the city of Metropolitan New York. This virus caused the accident (outbreak) in the city of New York which led to 63 people suffering from the symptoms of inflammation of the brain (encephalitis) and inflammation of the membrane around the brain (meningitis) and 5 of them died. Year after year, the virus spread to another state. In 1999, the virus spread to the third state, in 2000 expanded to 12 state, in 2001 expanded to 27 states and now West Nile virus found in almost every state in the United States and even into Canada (Figure 1). The number of patients who died in the attack and the virus is also increasing every year. From the CDC report, until November 26, 2002, has been found 3737 cases and 214 fatalities.
What is West Nile virus?
West Nile Virus is a virus that has a single positive RNA yarn (single positive-stranded RNA) as its genome with a length of about 9 kilobasa. The virus is classified Flavivirus group, along with the Dengue virus, Yellow Fever, Japanese encephalitis, St.. Louis encephalitis, Kunjin, and others. Just like most other Flavivirus, this virus makes mosquitoes as vectors, Culex pipiens especially kind, C. restuans, and C. quinquefasciatus. Besides mosquitoes, birds, especially crows also serves as a place pengidapannya (natural host), and the bird that is the instrument of the virus. Sirklus live virus move from bird to bird through the medium of these mosquitoes, and the virus multiplies during sirklus spin on this. Incidentally virus infection to humans and other animals such as horses and cause disease in humans and the infected animals.
West Nile Virus is a virus that has a single positive RNA yarn (single positive-stranded RNA) as its genome with a length of about 9 kilobasa. The virus is classified Flavivirus group, along with the Dengue virus, Yellow Fever, Japanese encephalitis, St.. Louis encephalitis, Kunjin, and others. Just like most other Flavivirus, this virus makes mosquitoes as vectors, Culex pipiens especially kind, C. restuans, and C. quinquefasciatus. Besides mosquitoes, birds, especially crows also serves as a place pengidapannya (natural host), and the bird that is the instrument of the virus. Sirklus live virus move from bird to bird through the medium of these mosquitoes, and the virus multiplies during sirklus spin on this. Incidentally virus infection to humans and other animals such as horses and cause disease in humans and the infected animals.
West Nile Virus was first discovered in Uganda in 1937. Until 1999, the virus has only been found in Africa, Asia and Europe. Since 1937, reported some unfortunate (outbreak), but not a serious problem because it only causes mild symptoms. Since the 1990s, the number of outbreaks causing death continues to increase, as evidenced by the outbreak in Romania in 1996, in Russia in 1999, and in Israel in 2000. But until the mid-1999 had never happened outbreak of West Nile virus in the United States.
Clinical symptoms and treatment of West Nile virus infection
Most West Nile virus infections do not cause any symptoms. About 20% amongst people infected cause mild symptoms that are flu-like symptoms (flu-like symptoms) such as fever (fever), headache (headache), body pain (body aches), eye pain (eye pain), and others, similar to the symptoms of viral infection of other Flavivirus group. Symptoms such as these was for 3 to 6 days. One in 150 infections cause serious symptoms, such as high fever (high fever), weak body, brain inflammation (encephalitis), inflammatory membrane around the brain (meningitis), muscle weakness (muscle weakness), and even to the mental changes. These symptoms are associated with damage to the nervous system, because these viruses and other Flavivirus attacks the human nervous system. Most of these serious symptoms afflict older people aged over 50 years who have weak immune power, and the death rate (mortality) in patients who cause serious symptoms is quite high. The mortality rate is higher in people who are more advanced. Once infected, the virus requires an incubation period of between 3-14 days before causing symptoms.
Due to the absence of a vaccine that can prevent infection with this virus, and also the absence of a cure infected patients, treatment can be performed on patients who were infected only in a hospital intensive care such as mechanical ventilation. Ribavirin and interferon-alpha2b evidenced showed a high cure rate against West Nile virus in vitro experiments, but no complete proof in clinical trials (emerg Infec Dis 8: 107-8 (2002)).
In addition, some groups are also developing vaccines. Among Acambis, a British company developing vaccines kimerik (chimeric vaccine), in which the envelope gene (one gene membrane-forming virus) of virus Yellow fever enveloep replaced with genes of West Nile virus. The vaccine is currently being entered clinical trials. In the same way the research team at the National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), USA is also developing vaccines kimerik West Nile virus and Dengue, which premembrane gene (gene also formed viral membrane) and gene of the dengue virus envelope is replaced with the corresponding genes of West Nile virus. But the vaccine is still in the experimental stage prekilinik (PNAS 99: 3036; 2002).
In addition, some groups are also developing vaccines. Among Acambis, a British company developing vaccines kimerik (chimeric vaccine), in which the envelope gene (one gene membrane-forming virus) of virus Yellow fever enveloep replaced with genes of West Nile virus. The vaccine is currently being entered clinical trials. In the same way the research team at the National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), USA is also developing vaccines kimerik West Nile virus and Dengue, which premembrane gene (gene also formed viral membrane) and gene of the dengue virus envelope is replaced with the corresponding genes of West Nile virus. But the vaccine is still in the experimental stage prekilinik (PNAS 99: 3036; 2002).
Diagnosis
Diagnosis is the standard used to measure IgM antibody-capture technique IgM antibody enzyme-linked immunosorbent assay (MAC-ELISA). Serum or Cerebral Spinal fluid (liquid nerve canal, usually taken in the backbone) of the patients who showed symptoms collected at the latest within 8 days of the onset of symptoms, and the IgM antibodies were measured. From the measurement of IgM people infected West Nile virus outbreak in New York in 1999 and 2000, 95% were positive (Ann Intern Med 137: 173-9 (2002)). However, this diagnosis will take approximately 1 week. For specific cases, this diagnosis is not perfect, because the people who receive the vaccine Yellow fever or Japanese encephalitis, or other Flavivirus infection also showed positive results in the IgM test. In this case, a specific test for the detection of Flavivirus mediated insect (arthropod-borne Flavivirus), should be used.
In addition, the isolation of the virus from the patient's serum is also one diagnosis, but it also takes a long time. Other diagnoses such as Reverse Transcription PCR and Real Time PCR is also a practical diagnostics for the detection of the viral RNA genome is concerned, because this diagnosis requires only a few hours.
New things are discovered in the West Nile infection in the United
In addition, the isolation of the virus from the patient's serum is also one diagnosis, but it also takes a long time. Other diagnoses such as Reverse Transcription PCR and Real Time PCR is also a practical diagnostics for the detection of the viral RNA genome is concerned, because this diagnosis requires only a few hours.
New things are discovered in the West Nile infection in the United
Symptoms were found in fatal West Nile infection is inflammation of the brain (encephalitis) and inflammatory membrane around the brain (meningitis). Muscle weakness (muscle weakness) is also a common symptom and is predikator patients infected by the West Nile virus. Has not been found any symptoms of polio (poliomyelitis) in West Nile virus infection. These symptoms are usually found in patients infected with polio virus and viruses are a group with polio virus (enterovirus). However, recently, of the cases in the U.S. found that West Nile virus, belonging to the Flavivirus group, also cause symptoms of poliomyelitis (New Engl J Med 347: 1279-80 (2002)). In addition, as a new thing, also found that the virus is also transmitted via transplantation (organ transplant) and blood transfusion (BMJ 325: 566 (2002)). West Nile virus is usually present, as well as other Flavivirus, transmitted by mosquitoes, so that transmission from person-to-person never be a material concern. But after proving that there is transmission through blood transfusion, blood donors must be checked before transfusion to someone.
Why does this virus can get in America?
There is no clear evidence why this virus menjejakan foot in the United States. But from the sequence analysis (sequence of nucleotides or amino acids), the virus has a high homology with the West Nile virus circulating in Israel from 1997 to 2000 (Science ¡¡286: 2333-7 (1999), emerg Infect Dis 7: 656-61 (2001)). Besides these two viruses have the same properties, where West Nile virus infections cause death in birds and humans only in the United States and Israel. In most cases, the virus does not cause the death of the birds as the place pengidapannya (its natural host). Because it was suspected that the virus was imported virus (Ann Intern Med 137: 173-9 (2002)).
The possibility of the entry of this virus into Indonesia and its prevention
Because in modern times it's easy to move from one place to another, viruspun easy to immigrate. If people move on a plane, get on a plane viruspun. This means that the possibility of West Nile virus to come to Indonesia is also not small. This virus uses crows and mosquitoes Culex sp. as a pengidapannyanya. If crows or mosquitoes infected with the West Nile virus that can get to Indonesia, atomatis virus will be imported and easily spread in Indonesia. This is because Indonesia is also included country where crows. Besides, Indonesia is also the country in which the mosquito Culex sp. many terdsitribusi.
People who come from the area is also an instrument terkenah unfortunate spread of this virus in Indonesia. Therefore, to prevent the arrival of the virus in Indonesia, one of the ways you can do is control the human, by examining the back of the disaster area, namely the United States. It would be perfect again if we can prevent the arrival of the birds or mosquitoes that fly from the U.S., but it is very difficult to implement. The Japanese government itself also provides a facility inspection / diagnosis for those who returned from the United States. Therefore, our government should think of it in order to avoid the entry of the virus into Indonesia. Prevention can be done by individuals who go to the United States is distancing oneself from the places where mosquitoes and crows love life.
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