Initial Infection in Mammals

• The parasite is introduced to the mammalian host through the bite of the tick. Infective sporozoites in the tick's saliva are injected into the cattle. During the bite, the sporozoites seek out and enter lymphocytes (white blood cells) within the blood of the host.
  
  

Lymphocyte Stage

• In the lymphocytes, the sporozoites developed into schizonts. The lymphocytes then become lymphobasts. These will multiply, replicating the parasite in the process. This allows the disease to proliferate very quickly throughout the system, usually causing the death of the infected host within three to four weeks.
  
  

Merozoite Stage

• As the infection grows, some schizonts will change into merozoites. These will leave the lymphocytes and enter into the bloodstream. They will then enter into red blood cells and develop into piroplasms.
  
  

Tick Stage

• When a tick bites an infected host, it ingests red blood cells that contain piroplasms. Within the insect's midgut, the piroplasms form kinetes that will migrate to the salivary glands, where they will become sporozoites and continue to reside there until the tick bites and infects another host.
  
  

Symptoms

• During a three- to four-week period, infected cattle will develop a disorder from the infection that is similar to lymphoma. It is a rapidly progressing disorder that will inevitably proving fatal to the animal.
  
  

Prevention/Solution

• Control of the disease by dipping or spraying cattle to kill ticks is effective, but expensive. Ticks are also becoming resistant to insecticides, making it more difficult to control the disease by these means.
  Diagnosis can be accomplished by examining recently collected blood or lymph samples for the parasite. Blood tests for specific antigens can also assist in diagnosing the illness.
  Cattle that survive the disease itself demonstrate immunity. Cattle can also be immunized against the disease using a live vaccine.
  
  

Research

• The Theileria parva genome is currently being studied because of its similarity to the plasmodium parasite, which causes malaria in humans, as well as the cryptosporidium parasite. This may lead to new drugs and vaccines that may prove to be effective against diseases of this kind.