Ticks are small tiny arthropods that suck blood.  They are the leading carriers of vector-borne diseases that plague humans.
In most cases, the disease is not caused by the tick bites but rather, the toxin in the tick’s saliva, secreted during the organism’s blood meal, transmitting the disease.
Some ticks are known to transmit microbes (bacteria) that cause illnesses, including Lyme disease and Rocky Mountain spotted fever amongst others, which can be transmitted between a few minutes to several hours. 
There are over 800 species of ticks throughout the world, but only two families of ticks, Ixodidae (hard ticks) and Argasidae (soft ticks), are known to transmit diseases or illness to humans.  Hard ticks have a scutum, or hard plate, on their back while soft ticks do not. Tick-borne diseases occur worldwide and they are considered second to mosquitoes worldwide.
Signs You Have Been Bitten by a Tick
Although most tick bites do not transmit pathogens, some bites do. It is very unlikely to infer if a tick is carrying pathogens visually. 
Tick bites normally do not show identifiable symptoms but should they exhibit symptoms, listed below are a few likely symptoms of tick-borne diseases ranging from minor to severe in no particular order: 
- Severe Headache
- Aches in the joints or muscles
- Swollen lymph nodes
- Rash or red streaks near bite site or full-body rash
On the other hand, if you have an allergy to tick bites, there is a possibility you might experience the following symptoms:
- Neck stiffness
- Breathing difficulties or heart palpitations
- Pain, swelling, or burning sensation at the bite sites