Peak expiratory flow rate (PEFR) is a hand held device which measures  how fast a person can exhale and is a reliable test for occupational asthma. Serial PEFR can be measured to see if there is a difference in ability to exhale at work compared to that in a controlled environment. A non-specific bronchial hyperreactivity test can be used to support the diagnose occupational asthma. It involves measuring the forced expiratory volume in 1 second (FEV-1) of the patient before and after exposure to methacholine or mannitol. Presence of airway responsiveness i.e. significant drop in FEV-1 can be seen in patients with occupational asthma.Specific inhalation challenges test consist of exposing the subjects to the suspected occupational agent in the laboratory and/or at the workplace and assess for asthma symptoms as well as a reduction in FEV1.Other tests such as skin prick test, serum immunologic testing and measurement of sputum eosinophils can also be useful in establishing the diagnosis of occupational asthma. Prevention
Several forms of preventive measures have been suggested to prevent development of occupational asthma and also detect risk or disease early to allow intervention and improve outcomes. These include: comprehensive programs, education and training, medical examinations, use of medications, reduction of exposures and elimination of exposures. Asthma symptoms and airway hyperresponsiveness can persist for several years after removal from the offending environment. Thus, early restriction from exposure to the trigger is advisable. Completely stopping exposure is more effective treatment than reducing exposure, but not always feasible.
The paralysis can occur in the absence of fever, headache, or other common symptoms associated with WNV infection. Involvement of respiratory muscles, leading to acute respiratory failure, sometimes occurs. West-Nile reversible paralysis, Like WNP, the weakness or paralysis is asymmetric. Reported cases have been noted to have an initial preservation of deep tendon reflexes, which is not expected for a pure anterior horn involvement. Disconnect of upper motor neuron influences on the anterior horn cells possibly by myelitis or glutamate excitotoxicity have been suggested as mechanisms. The prognosis for recovery is excellent. Nonneurologic complications of WNV infection that may rarely occur include fulminant hepatitis, pancreatitis, myocarditis, rhabdomyolysis, orchitis, nephritis, optic neuritis and cardiac dysrhythmias and hemorrhagic fever with coagulopathy. Chorioretinitis may also be more common than previously thought. Skin manifestations, specifically rashes, are common; however, there are few detailed descriptions in case reports, and few images are available. Punctate erythematous, macular, and papular eruptions, most pronounced on the extremities have been observed in WNV cases and in some cases histopathologic findings have shown a sparse superficial perivascular lymphocytic infiltrate, a manifestation commonly seen in viral exanthems. A literature review provides support that this punctate rash is a common cutaneous presentation of WNV infection. Cause
Virology
WNV is one of the Japanese encephalitis antigenic serocomplex of viruses. Image reconstructions and cryoelectron microscopy reveal a 45–50 nm virion covered with a relatively smooth protein surface. This structure is similar to the dengue fever virus; both belong to the genus Flavivirus within the family Flaviviridae.