HIV and disability: key links
In understanding the links between HIV and (other) disabilities, it is useful first to note how conceptions of disability have developed through several stages:

The impairment perspective considers disability a health problem or abnormality that is situated in an individual’s body or mind. This perspective is best expressed by the medical model which views disability in terms of disease, illness, abnormality and personal tragedy. The medical model assumes that disability is an intrinsic characteristic of individuals with disabilities. This assumption translates into practices that attempt to fix individuals’ abnormalities and defects, which are seen as strictly personal conditions.
The functional limitations perspective arose from attempts to expand the medical model to include non-medical criteria of disability, especially the social and physical environment. Nonetheless, the notion that impairments are the direct cause of disability remains central to this perspective.
The ecological perspective ... sees disability as resulting from the interaction of impairment, activity limitations and participation restrictions in a specific social or physical environment such as work, home or school. [...] There are many variations of the social model, but all portray disability as a social construct created by ability-oriented and ability-dominated environments ... According to the social model, even though impairment has an objective reality that is attached to the body or mind, disability has more to do with society’s failure to account for the needs of persons with disabilities.

The human rights model is a distinct subgroup of the social model. It understands disability as a social construct. The model is primarily concerned with the individual’s inherent dignity as a human being (and sometimes, if at all, with the individual’s medical characteristics).

Appropriately, this evolution in thinking about disability has, to varying degrees in different jurisdictions, been reflected in the law, such that HIV often falls under the rubric of “disability” for at least some legal purposes — and in particular, under anti-discrimination laws that can be used to challenge HIV-based discrimination as a form of discrimination based on disability. 
The need to respond to discrimination in various forms has featured prominently in the growing calls for partnership between HIV activists and disability activists.  Although in recent years the disability rights movement has made significant advances, similarly to PLHIV, people with disabilities often encounter stereotyping, discrimination and other infringement of human rights.

People with disabilities are among the most marginalized in the world, and the implications of HIV infection for people with disabilities have been largely ignored. Research has identified HIV as a significant but relatively unrecognized problem among people with disabilities worldwide [3-5]. It shows higher levels of illiteracy, unemployment and poverty among people with disabilities, factors linked to vulnerability to HIV and to a greater impact of HIV infection [6].