In short, no, a temperature of 99 degrees usually indicates a 'low grade fever' but this can be caused by a number of things, not just infection or a virus.
A temperature of around 98.6 is said to be a normal, standard temperature for a healthy human being. When this temperature is elevated and is slightly higher than usual, like the 99 degrees you are saying, this is usually just viewed as 'slightly high' and is an indication that your body is slightly warmer than it should be.
There are many reasons why this could be, maybe you're just too hot. Are you sitting too close to a heater or a radiator? Have you been working up a sweat? Are you wrapped up in too many layers of clothes? Try sitting in a cool area, sip a cold drink and take off any unnecessary layers and relax. Then check your temperature again in around 15-20 minutes. If your temperature is still showing as 99, there are probably other factors contributing to it.
One of the main reasons that your temperature would be 99 or more is a virus or an illness, such as the flu, a cold or a viral infection. When this is the case, ensure that you remember two very important things, rest and hydrate. When you are sick and/or have a low grade fever of around 99, make sure to drink plenty of water. When your body is too hot, more of the body's water and fluid is dried up and sweated outside of the body, so you have to make sure you are consuming lots of liquids to keep yourself hydrated and healthy. Becoming dehydrated can be exceptionally dangerous to your health. You must of course rest lots too, as doing even the most simple of things such as hoovering or changing your bed sheets can cause your temperature to rocket even higher as you work up a sweat.
