It is caused by a protozoan blood parasite (of the genus Babesia) that grows and replicates within the red blood cells of the cattle they infect.

In South Africa there are two cattle species of Babesia:
• Babesia bigemina (causing African Redwater)
• Babesia bovis (causing Asiatic Redwater)

The parasite is transmitted to cattle through tick bites.
(See Table 1 below )

The ticks carry the parasite in their saliva. Once the ticks feed on the animal host by taking a blood-meal, they transfer the parasites into the bloodstream of the animal

The disease can lead to high fatality rates if not addressed

CLINICAL SIGNS TO EXPECT WITH REDWATER

The incubation period of a disease is the timeframe from being infected with the parasite until cattle develops clinical symptoms.

For both Asiatic and African redwater this period takes on average 14 days but can vary between 10 and 16 days. 

The symptoms for African and Asiatic redwater are similar, making it difficult
to diagnose the type of redwater just based on clinical signs. Asiatic redwater is
however considered to be more severe. The disease progresses rapidly, and animals may die if not treated timeously.

 

One of the first symptoms to appear is a fever reaction.

FIRST 2 MONTHS

• A calf born to a previously unexposed cow will be susceptible to redwater during the first 2 months of life as there will be no protection given through colostrum.
• While a calf born to a previously immune cow will have colostral immunity for the first 2 months of life.

2 - 8 MONTHS

• Between the age of 2-8 months any calf will have a degree of a non-specific, natural immunity to redwater (irrespective of the immune status of the cow) - This natural, age-related resistance is strongest around 6 months of age but is still not absolute.

IMMUNE SYSTEM

• Factor such as stress, disease, high parasite burdens and malnutrition can suppress the immune system of the calf and make them susceptible
  to redwater. The same is true for older cattle, even if they were exposed to redwater previously and recovered.
• Older cattle contracting
  redwater for the first time can lead to severe clinical signs, high mortalities and production losses.

VACCINATE

• It is thus crucial for calves in areas where redwater is prone, to either be vaccinated, with a live attenuated vaccine, between 2-6 months of age or naturally exposed to the infected ticks while they fall within their immunity window. This
  way they can become infected, fight of the
  disease and build immunity without showing clinical signs of disease.