Selective mutism (SM) is an anxiety disorder in which a person who is otherwise capable of speech becomes unable to speak when exposed to specific situations, specific places, or to specific people, one or multiple of which serving as triggers. This is caused by the freeze response. Selective mutism usually co-exists with social anxiety disorder. People with selective mutism stay silent even when the consequences of their silence include shame, social ostracism, or punishment. Signs and symptoms
Children and adults with selective mutism are fully capable of speech and understanding language but are completely unable to speak in certain situations, though speech is expected of them. The behaviour may be perceived as shyness or rudeness by others. A child with selective mutism may be completely silent at school for years but speak quite freely or even excessively at home. There is a hierarchical variation among people with this disorder: some people participate fully in activities and appear social but do not speak, others will speak only to peers but not to adults, others will speak to adults when asked questions requiring short answers but never to peers, and still others speak to no one and participate in few, if any, activities presented to them. In a severe form known as "progressive mutism", the disorder progresses until the person with this condition no longer speaks to anyone in any situation, even close family members.
False negatives are often common with serum precipitins because of lack of testing reagents for many antigens.Precipitating IgG antibodies against fungal or avian antigens can be detected in the laboratory using the traditional Ouchterlony immunodiffusion method wherein precipitin lines form on agar plate. The ImmunoCAP technology has replaced this time-consuming, labor-intensive method with their automated CAP assays and FEIA (Fluorescence enzyme immunoassay) that can detect IgG antibodies against Aspergillus fumigatus (Farmers lung or for ABPA) or avian antigens (Bird Fanciers Lung). Differential Diagnosis
Organic dust toxic syndrome presents similarly with fevers, chills a few hours after exposure to bioaerosols with toxins from fungi, however this is not a true hypersensitivity reaction because it occurs on initial exposure without a preceding sensitization In chronic disease, HP must be differentiated from very similarly presenting idiopathic pulmonary fibrosis.Although overlapping in many cases, hypersensitivity pneumonitis may be distinguished from occupational asthma in that it is not restricted to only occupational exposure, and that asthma generally is classified as a type I hypersensitivity. Unlike asthma, hypersensitivity pneumonitis targets lung alveoli rather than bronchi.Similarly, sarcoidosis has noncaseating granuloma formation, however hilar adenopathy is often seen on chest radiographs. Treatment
The best treatment is to avoid the provoking allergen, as chronic exposure can cause permanent damage and acute disease is often self-limiting. The identification of the provoking antigen and its location must be ascertained by conducting an exposure assessment. Home cleaning is one method of antigen avoidance.