West Nile Fever is a disease caused by virus and transmitted by the bite of a mosquito. It can have different clinical manifestations, ranging from asymptomatic cases to severe cases involving neurological changes, such as encephalitis (inflammation of the parenchyma of the brain). The virus that causes this disease remains in nature thanks to alternating cycles of infections that affect birds and blood-sucking mosquitoes.
The first case of West Nile Fever was observed in Africa in 1937, and in the 1950s there were outbreaks in some African countries. In 1999, the disease reached the Americas, through the United States, and the first case in Brazil was registered in 2014, in Piauí.
Read more about: Virus Diseases
What is West Nile Fever?
West Nile Fever is a disease caused by a virus of RNA like Flavivirus, family Flaviviridae.The first case of West Nile Fever was registered, in 1937, in a woman who presented fever in Uganda, Africa, in a province called West Nile, which is why the infection is called this form.
The virus that causes West Nile Fever is a arboviruses, since their cycles involve vectors arthropods hematophagous and hosts vertebrates. The virus presents as natural hosts some species of birds wild animals, and these animals may or may not present clinical signs of the disease. Birds participate in the West Nile Fever cycle as virus amplifiers and sources of mosquito infection.
The virus can infect, through mosquito bites, mammals, like men and horses, considered accidental and terminal hosts. This name is given due to the fact that contamination occurs for a short period and viral levels are insufficient to infect mosquitoes. Thus, the disease transmission cycle ends. The main genus of mosquitoes identified as the vector of the disease is the Culex
West Nile Fever Transmission
The transmission of this disease occurs through the bite of mosquitoes contaminated with the virus, mainly mosquitoes of the genus culex, being this disease, therefore, of vector transmission. Transmission can still occur throughblood transfusion, organ transplantation, breastfeeding, and during gestation. It is noteworthy that these forms of transmission are much rarer when compared to insect bite transmission.
Read too: aedes aegypti – African mosquito and vector of various diseases
West Nile Fever Symptoms
West Nile Fever can present asymptomatically and even severely neurologically. In mild forms of the disease, the individual presents symptoms such as: febre, vomiting, nausea, headaches and in the eyes, muscle pain, red patches on the skin, and lymphadenopathy (change in lymph node size and consistency). In the most serious cases, the involvement of the central nervous system, encephalitis being the most common condition observed.
According to the Ministry of Health, there is a greater occurrence of the most severe form in individuals aged over 50 years. Also according to the ministry, if not treated properly, in very rare cases, West Nile Fever can kill.
West Nile Fever Diagnosis
West Nile Fever is diagnosed by the detection of IgM antibodies by the ELISA method in serum or cerebrospinal fluid. It is noteworthy that cross-reactions can occur if the patient has been vaccinated or infected with another flavivirus. O genre Flavivirus is the same as the viruses causing the dengue and of the yellow fever.
Read too: Zika fever - transmitted by the genus mosquito Aedes
West Nile Fever Treatment
There is no specific treatment for West Nile Fever. In this way, the disease will be treated in order to reduce its symptoms. Medicines for headaches and muscle pain may be recommended. More serious cases may require hospitalization.
West Nile Fever Prevention
The disease can be prevented by avoiding contact with its transmitting mosquito. For this, it is important to use repellents and put screens on windows and doors. It is also important to create ways to prevent the proliferation of the vector, ensuring that there are no places with stagnant water in homes, for example. Until now, there are no vaccines registered.
By Vanessa Sardinha dos Santos
Biology teacher
Source: Brazil School - https://brasilescola.uol.com.br/doencas/febre-do-nilo-ocidental.htm