Tick Fever RT-PCR in Cattle and Buffalo: Beyond the Smear

A blood smear lets a person see tick fever parasites under the microscope, while tick fever RT-PCR can also find light infections that a smear may miss. Used together, they give your vet a fuller picture of a cow or buffalo with fever, pale gums or falling milk. Neither test takes the place of the vet's own examination.

What is tick fever in cattle and buffalo?

Tick fever is a common name for illnesses caused by tiny parasites that live in the blood and are spread mainly by ticks. The three usually named in lab panels are theileriosis, babesiosis and anaplasmosis. In India ticks are most active in warm, humid weather, so the monsoon is a common time to see sick animals.

A sick animal may have fever, weakness, less appetite, pale gums and a drop in milk. These signs also fit other illnesses, so the cause has to be confirmed in the lab. See a vet promptly and do not wait for a report before getting care.

What does a blood smear show?

For a smear, a drop of blood is spread thin on a glass slide, stained with a dye and examined under a microscope. The reader looks for parasites inside the blood cells and for changes in the cells themselves. The Blood Protozoa (Blood Parasite Smear) is the basic version, and the Tick Fever Panel for Cattle & Buffalo (Theileriosis, Babesiosis, Anaplasmosis) is aimed at the three illnesses named above.

When an animal is clearly ill and the parasites are plentiful, a smear is a direct look at the problem. Its value depends on a well-made slide and a trained eye.

Where can a smear fall short?

A smear can only show what is on the slide. If the parasites are few, they may be missed. Parasite numbers also change as an illness goes on, and some parasites look alike on a slide, so naming the exact one can be hard.

Some animals recover, or never look ill, yet keep a small number of parasites in the blood. Such an animal is called a carrier. Ticks that feed on a carrier can pick up the parasite and pass it to other animals, which is one reason vets pay attention to them.

How does RT-PCR add to the smear?

RT-PCR means real-time PCR. It is a lab method that looks for the genetic material of a parasite in a blood sample and copies even a tiny trace until it can be measured. It can find a light infection and can help name which parasite is present.

The Bovine Tick Fever RT-PCR Panel (Theileria, Babesia & Anaplasma) looks for the main tick-borne blood parasites in one test, and the exact list is confirmed when you book. If your vet suspects one parasite in particular, a single test may be asked for instead: Theileria annulata RT-PCR, Babesia bigemina / bovis RT-PCR or Anaplasma marginale RT-PCR.

RT-PCR has limits too. A positive result in an animal that looks well may point to a carrier rather than the cause of today's illness. Your vet weighs it against the signs.

Why do the two tests work better together?

Each test covers what the other can miss:

• If the smear shows parasites and RT-PCR names them, your vet has a clear answer.
• If the animal is plainly ill but the smear looks clear, RT-PCR may find what the slide missed.
• If RT-PCR is positive but the smear is clear, your vet may think of a carrier or a light infection, and will keep looking for other causes.

Anaemia, meaning too few red blood cells, is common in tick fever, so a Complete Blood Count (CBC) is often added. The Tick Fever RT-PCR Pack brings a smear panel, a CBC and the RT-PCR panel together for cows and buffaloes with fever or anaemia.

What sample is needed?

The usual sample is whole blood in a tube with EDTA, a chemical that stops the blood from clotting. Your vet normally draws it. The lab confirms what it needs when you book, so ask before you collect or store any sample yourself.

A registered veterinarian reads all the results together with the signs, the tick history of the farm and the animal's earlier illnesses. Ask your vet about tick control for the herd as well, because testing finds the parasite but does not keep ticks away.

Read next

To fit tick fever checks into the whole farm year, see Dairy Farms Around Bhopal: A Yearly Herd Testing Calendar. For a wider view of the other tests a dairy farm may need, Lab Tests Every Dairy Farmer Should Know About is a good place to start.

Testing in Bhopal

For tick fever tests, your vet draws the blood and the lab at C-200, C Sector, Shahpura, Bhopal receives it. Free sample collection is available anywhere in Bhopal, and farmers in other districts can send blood by courier, bus parcel or through their vet. Call or WhatsApp +91 88175 01118 and the lab confirms the method, sample needs and reporting time when you book.