West Nile Fever case in Piaui is concerning, says expert

Publicação: 14 de December de 2014

Surveillance system detects patient infected with the West Nile Fever virus right after implementation. Other undetected cases could appear in the country

About 75% of the people bitten by the virus vector do not develop the disease, but there can be severe consequences in 1% of the cases

About 75% of the people bitten by the virus vector do not develop the disease, but there can be severe consequences in 1% of the cases

Imagine being bitten by a mosquito and developing a severe neurological disease. This is what happened to a 52-year old farmer who lives in Aroeira do Itaim, in Piaui State, who had encephalitis and was diagnosed with the virus of the West Nile Fever. The agent is transmitted by a mosquito from the Culex genus, the common mosquito, and could be health threatening. After the discovery of the case, the matter gained national attention and the questioning whether the disease is epidemic in the country or not.

According to the Health Ministry (HM), this is an isolated event and does not have relevant epidemiological meaning nor is a public health threat in Piaui State or Brazil. The office also informed that four other people presented suspicious neurological symptoms, but the risk of being the disease known as West Nile Fever was ruled out after laboratory exams. 18 other people from the region were also tested, but reported negative for the virus.

According to the infectious diseases expert Dr. Dalcy Albuquerque Filho, representative of the Brazilian Society of Tropical Medicine in Brazil’s Federal District (BSTM/DF), there is no reason to panic. However, although it is an isolated case, the situation is concerning. “Even though we have already identified seropositive animals for the disease, we had never detected the virus in humans and this is new”, affirmed. For him, the most important is to establish surveillance rules, especially environmental rules to track and investigate the problem. “The main indicator is bird death. It is important to verify if there are happening many deaths, especially in Piaui, to check if it is due to the West Nile Fever and, consequently, try to block the virus’ spread”,s said.

Two hypotheses are probable regarding the presence of the West Nile Fever virus in Brazil’s northeast, according to Dr. Marcelo Adriano Vieira, from the Teresina Health Foundation’s Epidemiology Office (FMS). The doctor helped identifying the case of the Aroeiras do Itaim’s farmer.

The first is that other people have already been infected by the virus, but the disease was not diagnosed in the health system. “the disease may already be endemic in Brazil in a lower level, this is, not causing an outbreak. Since the diagnose resources are very scarce, as they are in the majority of the health services, some cases may not have been identified as West Nile Fever virus”, said the neurologist.

The other theory is that an epidemic could be in a first stage. “It is possible that we discovered this case very early, even before reaching epidemic proportions, explained, adding this is a positive aspect for Piaui’s health system, once it was able to identify the disease.



Before the confirmation of the case, the Health Ministry, in a partnership with the Piaui State Health Secretary and the City Health Foundation, sent a team of professionals including veterinarians, nurses, physicians and biologists to verify if there were other manifestations of the disease.

According to Dr. Vieira, there were no new records of the disease. “The first concern was to check if there was another ill person close to the place were the farmer was infected. However, no one else presented fevers or neurological manifestations”, affirmed while adding that despite this fact, the team collected blood from horses, birds and chickens to verify if these animals are carrying the virus or antibodies. “The results showed that three birds carried antibodies, what proves that they had previous contact with the virus earlier”, commented.

Still according to the neurologist, other measures were put in action. “Besides evaluating the patient’s neighbors and family, a retrospective of people who were hospitalized before presenting fevers or any other neurological manifestation is in course, with sample collection for analysis. It was also decided that from that moment on, whoever becomes ill will be tested”, he said.

In an official report, the Surveillance and Health Attentions Directory from the State Health Secretary informed that additional studies are in course in the region and should be released in short. “The state’s hospital network and the epidemiological surveillance services are alert for the possibility of detecting new cases. The control measures regarding the situation will be released and updated by the Health Ministry at each novelty, being necessary at first the adoption of certain cautions when exposing to mosquitos and their proliferation”.


Transmission, symptoms and treatment

The virus is not transmitted person-to-person. The mosquito bites a wild bird and, then, humans, horses or other birds. Humans and horses can develop the disease, but are unable to retransmit the virus to another mosquito. Besides this, the contact between humans is insufficient to transmit the virus.

About 75% of the people bitten by the virus’ vector and do not develop the disease, but there can be severe consequences in 1% of the cases. The disease causes high fever, stiffness of the neck, disorientation, paralysis, muscular weakness and shivering. In more severe cases it is possible to  develop inflammations in the brain (encephalitis), cerebral membranes (meningitis), spinal cord (myelitis) or peripheral members (polineurite).

There is no specific treatment for the West Nile Fever. The most adequate method  is support and involves hospitalization, intravenous fluid reposition, ventilation support and prevention of secondary infections.…