Theileria

If your initial thought is, “I’ve never seen a tick on my farm; this article doesn’t apply to me,” please read on. This is a common misconception among farmers in Marlborough, even when faced with a very pale cow. Ticks are adept at sucking blood without being noticed. Unless you regularly inspect your livestock’s most intimate areas, you will likely miss them.

Understanding Theileria

Theileria, carried by the ticks, causes red blood cells in the cattle host to burst. It only takes one Theileria-carrying tick to wreak havoc on a herd. A single bite can infect a cow, and any subsequent ticks feeding on that cow will pick up the parasite and pass it on to others. Without measures to control the tick population, the spread of Theileria can become uncontrollable. It cannot spread without ticks!

Experiencing Theileria during the calving season in a dairy herd can be particularly devastating. These cows are already in a delicate state due to energy demands, health, and weather conditions, making them susceptible to anaemia and potentially death. Beef cows are also at risk, especially around calving and when other health factors, such as trace element deficiencies or other diseases, are present, or when weather conditions favour tick overpopulation.

Treatment focuses on three aspects:

1. Tick treatment: BANTIX (nil meat/milk withhold)

• Timing: When to start depends on year/region. Usually, whole herd treatment every six weeks starting from when the frosts end. This year we will be treating early and every 4 weeks due to prime tick-breeding weather.
• Duration: When to stop depends on a couple of factors; usually when it dries up in Marlborough ticks do not do as well. Plus, once we are through mating, we no longer want to stop these girls getting infected. Might sound counter intuitive, but a level of immunity is built up from exposure to Theileria. Hence the first couple of years of herd exposure are generally the worst.
• Goal: The goal with Bantix is to protect the cows when they are most vulnerable and keep them at their fittest through mating. After this time, you are more likely to see milder symptoms e.g. drop in milk/slightly depressed or slow cow.

2. Supportive treatment – BIVATOP & METACAM

• BIVATOP: Theileria is not a bacterium and cannot be treated with antibiotics. Bivatop however helps with other subclinical infections that put a strain on the immune system. Recovery is better in cows that have a dose.
• Metacam: Metacam keeps them feeling well enough to eat/drink while dealing with the worst of the infection.

Both treatments last three days, so you only need to inject on day one and then leave the cow alone in the paddock while she recovers (see below).

3. Rest and care

• Rest: Animals with clinical Theileria are anaemic, exhausted, immunosuppressed, and liable to a heart attack if overstimulated. If a Theileria cow is down, leave her there. If she is in an awkward place, move her with as little stress as possible using machinery and appropriate restraints.
• Nursing: Bring food and water, cover her if the weather is bad and prop her up. She is using all her remaining red blood cells to keep breathing while her immune system fights the Theileria – the least we can do is give her a hand!
• The use of three-day long injectables is one less intervention to cause stress every day.
• OAD milking: This may be an option if she is mildly affected, but many have to stop milking entirely.

Preventative measures

Blood testing for Theileria is advisable, especially in areas where the disease has not been previously detected. Remember that bought-in stock and transport vehicles can introduce ticks, leading to unexpected outbreaks.

While we hope many of you will never encounter Theileria, being prepared and informed is crucial. Keep an MPI FANI card in your pocket and you will be in a good position to identify cases if they do spring up.