Ticks pathogenesis

Question 1

What is Ixodes ricinus a vector of?

Answer 1

very successful vector:

1. transmits Lyme disease
2. louping ill (sheep),
3. Bovine Babesiosis, babesia divergens - red water (cattle);
4. Anaplasma
5. rickettsias

Question 2

Talk about babesia divergens

Answer 2

1. commonly known as red water
2. Cattle
3. Most common south west and Ireland
4. can be transmitted transovarially (from female to egg)

Question 3

Pathogenesis of babesia divergens

Answer 3

1. cattle
2. Progessive haemolytic anaemia results in haemoglobinaemia and haemoglobinurea
3. both these cause high fever, listlessness, dehydration and diarrhoes
4. untreated - progresses to severe haemolytic anaemia
5. can be cause of sudden death

Question 4

Wher is Rhicephalus microplus found and what is it a vector of?

Answer 4

1. Tropics/ subtropics
2. Cattle ONLY
3. Babesia bigemina
4. Babesia Bovis (highly pathogenic)

Question 5

Talk about babesia bovis

Answer 5

1. highly apthogenic
2. acute disease 1-2 weeks after tick commences feeding
3. Fever, low parasitaemia (hard to find), neurological sings due to sludging haemoglobinuria in CNA - Red water, death within days
4. Endemic Stability

Question 6

Talk about endemic stability

Answer 6

1. Bovine Babesiosis
2. In endemic areas prevalence in cattle and transmission rates are relatively high
3. most animals are exposed when young - protected by INVERSE AGE RESISTANCE so disease uncommon
4. Acts as a vaccination
5. as long as exposed to ticks throughout life acting as “boosters”
6. this maintains immunity within the population
7. Most cattle exposed when young hence protected by INVERSE AGE RESISTANCE so disease is uncommon
8. So most clinical disease may NOT be in areas where babesiosis is the highest as cattle are immune and receiving boosters

Question 7

If endemic stability in an area why does disease still occur?

Answer 7

1. Occur when this endemic stability is disturbed
2. e.g. breakdown tick populaiton - fewer “boosters” so immunity falls
3. e.g. New animals that have never encountered babesia before

Question 8

What tick is a vector of HEart water

Answer 8

Ehrlichia ruminantium – vector of Heartwater

2. Amblyomma species
3. very colourful tick!

Question 9

Heart water

Answer 9

• In acute cases animals may drop dead within a few hours of veveloping a fever, sometimes without any apparent slinical signs
• Post mortum  lot of fluid around ehart
• Exagerated respiratory distress (not always seen)
• Subject to endemic stability in same way as babesiosis. Endemic areas tend to see not much disease
• Climatic changes ticks are changing in distribution. Being found in areas never found before

Question 10

Tick control in the tropics

Answer 10

Organo phosphates (dips) Pyrethroids and AMitrz

Threat of babesiosis is such that prophylactic measures usually taken – either (in Australia) vaccination with live attenuated vaccine, or worldwide, regular dipping or spraying for ticks with acaricides (but widespread resistance issues).
Cattle are plunge dipped or sprayed (race or pour on)