There is also evidence for the validity of a genetic component contributing to blood-injection-injury phobias and animal phobias, although this evidence did not support the idea that other specific phobias had genetic influence. Blood-injection-injury phobias are also believed to be the most heritable among specific phobias.The classical conditioning model of learning has also been used to suggest that a phobia will be learned when an event that causes a fear or anxiety reaction is paired with a neutral event. An example of this model is when being near a dog (neutral event) is paired with the emotional experience of being bitten by a dog, resulting in a chronic fear which is described as a specific phobia to dogs. An alternative proposed mechanism of association is through observational learning. According to this theory, a person may internalize another persons fears about a specific object or situation through observation of their reactions. Diagnosis
Diagnosis in the ICD or the DSM requires a marked fear, anxiety or avoidance that is long-lasting (greater than six months) and consistently occurs in the presence of the feared object or situation. The DSM-5 that the fears should be out of proportion to the danger posed, compared to the ICD-10 which specifies that the symptoms must be excessive or unreasonable. Minor differences have persisted between the ICD-11 and DSM-5.In the DSM-5, there are several types which specific phobia can be classified under:

Animal type – Including fear of spiders (arachnophobia), insects (entomophobia), or dogs (cynophobia).
Natural environment type – Including fear of water (aquaphobia), heights (acrophobia), lightning and thunderstorms (astraphobia), or aging (gerascophobia). Situational type – Including the fear of small confined spaces (claustrophobia), or the dark (nyctophobia). Blood/injection/injury type – Including fear of medical procedures, including needles and injections (trypanophobia), fear of blood (hemophobia) and fear of getting injured (traumatophobia). Other – Situations which can lead to choking or vomiting, and childrens fears of loud sounds or costumed characters.Although the avoidance resulting from specific phobia is comparable to other anxiety disorders, differential diagnosis is done through examining underlying causes for the behavior. Agoraphobia is also considered distinct from specific phobia, along with substance use disorders, and avoidant personality disorder. The occurrence of panic attacks is not itself a symptom of specific phobias and falls under the criteria of panic disorder. Treatment
There are a variety of treatment options available for specific phobias, most of which focus on psychosocial interventions. Different psychological treatments have varying levels of effects depending on the specific phobia being addressed. Cognitive behavioral therapy (CBT)
Cognitive behavioral therapy is a short term, skills-focused therapy that aims to help people diffuse unhelpful emotional responses by helping people consider them differently or change their behavior. CBT represents the gold standard and first line of therapy in specific phobias. CBT is effective in treating specific phobias primarily through exposure and cognitive strategies to overcome a persons anxiety. Computer-assisted treatment programs, self-help manuals, and delivery by a trained practitioner are all methods of accessing CBT.