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H5N1 Flu Symptoms

H5N1, the lethal avian flu that first emerged in 1997 in Hong Kong and is now entrenched in an even more lethal strain in a half dozen Southeast Asian countries. It has recently killed scores of farmers and poultry workers who have had direct contact with sick birds.

Since H5N1 is an influenza virus, symptoms similar to those of the common flu, such as fever, cough, sore throat, and muscle aches, can develop in infected humans. However, in more severe cases, pneumonia and respiratory failure can develop and eventually cause death. Patients with H5N1 avian influenza have rarely had conjunctivitis, unlike human cases of infection by the H7 virus.

The H5N1 virus causes an exaggerated response of cytokines (such as TNF-a), and this could result in a toxic-shock-like syndrome (including fever, chills, vomiting and headache), which ultimately results in death. In many diseases (including H5N1 in humans), a 'cytokine storm' also called hypercytokinemia is triggered by the infection. Cytokines are hormones that regulate the immune sytem. When released at the right time in the proper amounts, cytokines can help fight infections and regulate processes through out the body.

But unfortunately the deadly strains of H5N1 virus is not only partially resistant to the cytokines that are involved in fighting viruses, but it also reduces the production of anti-inflammatory cytokines and in the process, it makes the immune system go out of control.