What type of disease should a licensee avoid contact with when dealing with clients?

The correct answer is that a licensee should avoid contact with any communicable disease when dealing with clients. Communicable diseases are those that can be transmitted from one person to another, either directly or indirectly. This category includes a wide range of infections such as colds, flu, tuberculosis, and more serious illnesses like HIV and hepatitis.

It is essential for licensees in the health and sanitation fields to maintain strict hygiene practices to prevent the spread of these diseases, ensuring the safety of both themselves and their clients. This awareness is a critical part of public health and sanitation protocols, as it helps to mitigate risks associated with direct contact with clients who may carry transmissible pathogens.

The other types of diseases listed in the choices do not pose the same level of risk in terms of transmission. Non-communicable diseases, for instance, such as diabetes or heart disease, do not spread between individuals and therefore do not require the same level of caution regarding client contact. Additionally, focusing only on specific types like parasitic or viral infections does not adequately encompass the full range of communicable diseases and could lead to gaps in safety practices.

Thus, the comprehensive approach outlined in the correct answer is crucial for maintaining health standards in client interactions.