The West Nile Fever is a disease caused by the West Nile Virus (WNV), which is part of the viral genus Flavivirus – like the Japanese encephalitis virus, dengue fever virus and more. The West Nile Virus infects mostly birds, but may infect mammals (like people) and even some reptilians, when bitten by an infected mosquito. The most common vector of WNV are mosquitoes from the Culex genus.
The virus and the disease got their name “West Nile Virus/Fever” as they were first identified and reported to the scientific world in West Nile District of Uganda in 1937. However, the disease is probably among us long before that. It is suspected to be the cause of death of Alexander the Great.
Most people infected with the West Nile Virus will probably not know it, as in most cases (nearly 80%) the infection is asymptomatic. The majority of the humans that do catch the disease (nearly 97% of the sick people) will experience relatively mild fever that we call West Nile Fever.
Only a minority of the infected people (less than 1% of the total infected people and about 3% of the sick ones) will experience West Nile Meningitis or Encephalitis, which in many cases has severe consequences, including death.
West Nile Fever symptoms usually appear 2 to 8 days after infection (i.e. by an infected mosquito bite, see ahead). The symptoms are normally fever, weakness, headache, chills, sweating, swollen lymph nodes, drowsiness, pain in the joints and other flu symptoms. Most symptoms will last 1 week to 10 days. Some symptoms like swollen lymph nodes, may last longer.
The West Nile Virus is an Arbovirus, which means that it belongs to a group of viruses that are transmitted only by arthropod vectors like mosquitoes. In order for a person to get infected with West Nile Virus, he/she must get bitten first by an infected mosquito female (since only the females are biting).
The best West Nile Virus carrier pool is the bird population. Mosquitoes are transferring West Nile Viruses among birds and thus maintaining the pool. The mosquito itself will get infected only if it will bite an infected bird first. Infected birds have high West Nile Virus density in their blood, enough to infect the biting mosquito.
When biting an infected mammal, like a human for instance, the mosquito will absorb West Nile Viruses with the blood meal. However, since the West Nile Virus density in an infected human blood is low relative to birds, the mosquito female will absorb only a small dosage of viruses, small enough for its immune system to get over it. Therefore, viruses that infect animals other than birds are going into a dead-end.
Two to three days after the mosquito female had bitten a WNV infected bird, it will oviposit (lay eggs). Couple of days more and it is ready to bite again – searching for the second victim. If by the time it will bite again the West Nile Virus has spread into its salivary glands, the new victim (that can be an unfortunate human) will be infected with the virus.
Read more valuable info on mosquito life cycle and how to get rid of the mosquito bites to avoid WNV infection and its risky outcomes.
The virus and the disease got their name “West Nile Virus/Fever” as they were first identified and reported to the scientific world in West Nile District of Uganda in 1937. However, the disease is probably among us long before that. It is suspected to be the cause of death of Alexander the Great.
Most people infected with the West Nile Virus will probably not know it, as in most cases (nearly 80%) the infection is asymptomatic. The majority of the humans that do catch the disease (nearly 97% of the sick people) will experience relatively mild fever that we call West Nile Fever.
Only a minority of the infected people (less than 1% of the total infected people and about 3% of the sick ones) will experience West Nile Meningitis or Encephalitis, which in many cases has severe consequences, including death.
West Nile Fever symptoms usually appear 2 to 8 days after infection (i.e. by an infected mosquito bite, see ahead). The symptoms are normally fever, weakness, headache, chills, sweating, swollen lymph nodes, drowsiness, pain in the joints and other flu symptoms. Most symptoms will last 1 week to 10 days. Some symptoms like swollen lymph nodes, may last longer.
The West Nile Virus is an Arbovirus, which means that it belongs to a group of viruses that are transmitted only by arthropod vectors like mosquitoes. In order for a person to get infected with West Nile Virus, he/she must get bitten first by an infected mosquito female (since only the females are biting).
The best West Nile Virus carrier pool is the bird population. Mosquitoes are transferring West Nile Viruses among birds and thus maintaining the pool. The mosquito itself will get infected only if it will bite an infected bird first. Infected birds have high West Nile Virus density in their blood, enough to infect the biting mosquito.
When biting an infected mammal, like a human for instance, the mosquito will absorb West Nile Viruses with the blood meal. However, since the West Nile Virus density in an infected human blood is low relative to birds, the mosquito female will absorb only a small dosage of viruses, small enough for its immune system to get over it. Therefore, viruses that infect animals other than birds are going into a dead-end.
Two to three days after the mosquito female had bitten a WNV infected bird, it will oviposit (lay eggs). Couple of days more and it is ready to bite again – searching for the second victim. If by the time it will bite again the West Nile Virus has spread into its salivary glands, the new victim (that can be an unfortunate human) will be infected with the virus.
Read more valuable info on mosquito life cycle and how to get rid of the mosquito bites to avoid WNV infection and its risky outcomes.
West Nile Virus - WNV
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