Lesson 40 - Vector Borne Diseases in Production Animals

stable fly (stomoxys calcitrans)

What vector is this?

face fly (musca autumnalis)

What vector is this?

culicoides (biting midge)

What vector is this?

biting and sucking

What kind of fly is the stable fly?

ixodes

What vector is this?

1. non-biting

2. feed on the secretions around an animal's eyes, nose, and mouth

3. primary vector for diseases that affect the eyes and skin

What are the characteristics of the face fly?

dermacentor spp.

What vector is this?

rhipicephalus/boophilus tick

What vector is this?

moist warm conditions and stagnant water

Where are biting midges found?

three

How many host life cycles fo ixodes spp. have?

large, reddish-brown ticks, recognized by white, silvery, or grayish mottled markings on their upper shield

How can you recognize dermacentor ticks?

1. cattle tick

2. brown dog tick

What is another name for rhipicephalus/boophilus tick?

yellow legs

What is a recognizable feature of rhipicephalus/boophilus tick?

blacklegged tick

What is another name for Ixodes/deer tick

american dog tick

What is another name for dermacentor?

lonestar tick

What is another name for amblyomma?

Erlichia ruminantium

What is the pathogen that causes heartwater disease?

no

Is heartwater disease zoonotic?

amblyomma

What vector spreads heartwater disease?

1. Infects endothelial cells and neutrophils

2. Fever

3. edema heart and lungs

4. Death

What are the clinical signs of heartwater disease?

PCR (staining issues)

What test is used to diagnose heartwater disease?

tetracyclines

How is heartwater disease treated?

vaccine if endemic

How is heartwater disease prevented?

anaplasma marginale

What pathogen causes bovine anaplasmosis?

Dermencator/Boophilus

What vector causes bovine anaplasmosis?

erythrocytes

What cell does anaplasma marginale infect in cattle?

a. marginale

What is the most pathogenic anaplasmosis in cattle?

1. Dermacentor ticks (also Ixodes and Boophilus)

2. Tabanid flies (big flies that bite: horse flies, deerflies)

What are the vectors for anaplasmosis?

2-8 weeks

What is the incubation period for anaplasmosis?

anemia, icterus, fever, dead w/in a few hours

What are the peracute clinical signs of anaplasmosis?

die over a couple of days

What are the acute clinical signs of anaplasmosis?

subclinical

How does anaplasmosis present in calves

30-50% mortality

How does anaplasmosis present in adults >2 yo?

relapse with immune suppression

What can happen to carriers of anaplasmosis?

1. Fever, depression, anorexia

2. Hemolytic crisis leading to tachycardia, dyspnea/tachypnea, pale and/or yellow mucous membranes, reluctance to move

3. Ticks visible

4. discoloured dark yellow and brown urine

What are the clinical signs of anaplasmosis in cattle?

1. within vessel

2. hemoglobin released to bloodstream

3. hemoglobinurea

What are the characteristics of intravascular hemolysis?

1. spleen and liver hemolysis

2. liver processes products

3. hyperbilirubinemia

4. bilirubinuria

What are the characteristics of extravascular hemolysis?

bilirubin

When testing the urine of cattle with anaplasmosis, which would be of high value?

1. risk region

2. history

3. clinical signs

4. splenomegaly on PM

What should you consider when diagnosing anaplasmosis?

1. Blood smear (Giemsa)

2. ELISA

3. PCR

What test do you use to diagnose anaplasmosis?

1. Daily or LAoxytetracycline

2. Imidocarb (extra label in the US)

3. Supportive care

4. Treat/remove ticks

How is anaplasmosis treated in cattle?

can't be used as food animals

What happens if you treat cattle with imidocarb?

prevent the development of antibiotic-resistant bacteria that can threaten human health

Why is enrofloxacin (fluoroquinolone) not used to treat anaplasmosis?

1. Injectables - macrocyclic lactone

2. Pour-ons - macrocyclic lactones, permethrin/flumethrin

3. Spray - organophosphates/amitraz/ deltamethrin

4. Dipping Vats - organophosphates

5. Insecticide Ear Tags (localized treatment)

What are the tick treatments for cattle?

1. How long can live off host? (prevent re-infection

2. Duration of activity of product used

3. Is the product ovicidal/treat all stages?

What does the timing of tick treatment and prevention depend on in cattle?

1. Control biting insects and blood transfer

2. Move into endemic areas while young

3. Vaccines (not allowed in US)

4. Control outbreaks

How is anaplasmosis prevented?

small ruminants

What does anaplasma ovis primarily affect?

yes, but much less common

Can small ruminants get a. marginale?

a. marginale

What are the clinical signs, transmission, and treatments of anaplasma ovis the same as?

1. Seen in cattle but not in the US

2. Much reduced pathogenicity of A. marginale

3. Vaccine available in areas where it is a problem

4. Look for location of pathogen on blood smears

What are the characteristics of anaplasma centrale?

Babesia bigemina and B. bovis

What kinds of babesia are notifiable in the US?

B. divergens

What kind of babesia is endemic in the UK?

1. Boophilus/Rhipicephalus ticks in USA

2. Ixodes tick in Europe/UK

What ticks spread babesia?

sporozoites are inoculated into the vertebrate host by ticks and invade red blood cells (RBCs) where they transform into trophozoites causing lysis

What is the pathogenesis of babesia?

2-3 weeks

How long does it take for babesia to become clinical?

1. transovarially between tick generations

2. fomites and mechanical vectors contaminated by infected blood

3. calves can become infected in utero

4. maintained in subclinically infected animals

How can babesia be transmitted?

hemoglobinuria

What would urine analysis of a cow with intravascular hemolysis would show?

icterus

How does a cow with RBC lysis represent?

1. High fever

2. Ataxia and incoordination

3. Anorexia

4. Production of dark red or brown-colored urine

5. Tachycardia, tachypnea/dyspnea

6. Sometimes nervous signs associated with sequestration of infected erythrocytes in cerebral capillaries

7. anemia and hemoglobinuria later in disease

8. Bulls may become infertile

9. cows may abort

What are the clinical signs of babesia?

anaplasma

What is this?

babesia

What is this?

1. blood transfusion

2. tick treatment

3. NSAIDs

How is babesia treated?

1. treat/control the ticks

2. Vaccination in some countries (not US)

How is babesia prevented?

new forest eye

What is this?

moraxella bovis

What bacteria causes new forest eye?

1. fimbriae and pili proteins that allow it to adhere to the corneal epithelial cells and conjunctiva

2. 𝛽-haemolysin toxin that lyses the corneal epithelial cells

3. destructive enzymes, including pathogenic fibrinolysin, lipase, hyaluronidase, and aminopeptidases, which break down tissue and cause ulceration

What are the bacterial mechanisms that contribute to moraxella bovis infections?

intense ultraviolet (UV) radiation (sunlight) and dust act as predisposing factors by irritating the eye and making it easier for the bacteria to take hold

What are the environmental factors that contribute to moraxella bovis infections?

young stock are more susceptible to severe disease

What is the host susceptibility for moraxella bovis infections?

asymptomatic carriers often harbor the bacterium, facilitating the spread in a herd

What are the carrier animals for moraxella bovis infections?

flies acting as mechanical vectors through direct contact with infected lacrimal secretions, saliva, or nasal discharges

How is moraxella bovis spread?

skin, eyes, mucosa, mammary

What systems can flies transmit bacteria to?

1. extreme pain, causing animals to shut their eyes, especially in sunlight (photophobia)

2. Excessive lacrimation

3. mucopurulent discharge in later stages

4. Cloudiness of the cornea, progressing to ulcers

5. temporary or permanent blindness in severe, untreated cases

6. significant weight loss due to disrupted grazing

What are the clinical signs of moraxella bovis?

penicillin

How is moraxella bovis treated?

bacterin vaccine

How is moraxella bovis prevented?

fly control

How can transmission of moraxella bovis be reduced?

summer mastitis

What is this?

trueperella pyogenes

What bacteria causes summer mastitis?

headfly (hydrotaea irritans)

What vector transmits summer mastitis?

low-lying, damp, wooded, or sheltered pastures

What environment is summer mastitis prevalent in?

late summer and autumn, particularly during warm, humid, and lowwind conditions

What time of year is summer mastitis prevalent?

dry cows and heifers

What groups are at high risk of developing summer mastitis?

1. immediate veterinary attention is required

2. Systemic, long-acting antibiotics (e.g., penicillins)

3. NSAIDs

4. Frequent manual removal of pus from the teat is crucial

5. Separate infected animals from the herd immediately

6. Teat amputation in severe chronic cases

How is summer mastitis treated?

1. fly control

2. Avoid grazing vulnerable stock in high-risk, sheltered areas

3. Use of sealants during the dry period to protect the teat canal

4. Regular, daily inspections of dry cows and heifers, particularly during July and August (months with high numbers of flies)

How is summer mastitis prevented?

infectious, primarily vector-borne viral disease that affects wild and domestic ruminants such as sheep, goats, cattle, buffaloes, deer and most species of African antelope, and camelids as vertebrate hosts

What is blue tongue virus?

culicoides midges

How is blue tongue virus transmitted?

reportable disease

What is significant about blue tongue virus?

1. vaccines

2. mosquito nets

3. chemical mosquito repellents

4. eliminate stagnant water

5. remove bedding and manure once a week

How can blue tongue virus be prevented?

1. usually subclinical except BTV-8

2. fever

3. hyperemia and congestion

4. facial edema and hemorrhages

5. erosion of the mucous membranes

6. coronitis and laminitis

7. pleural and pericardial hemorrhages.

What are the clinical signs of blue tongue virus?

increase in vascular permeability

What can the clinical signs of blue tongue virus be attributed to?

1. Clinical signs

2. Time of year/vector present

3. Local surveillance

What should be considered with blue tongue virus diagnosis?

1. PCR of blood or tissue at time of disease

2. ELISA once seroconverted

What tests can diagnose blue tongue virus?

orthobunyavirus affecting cattle, sheep, and goats across Europe, causing transient illness in adults (fever, diarrhea, reduced milk yield) and severe congenital malformations or abortions in calves when infected during pregnancy

What is schmallenberg virus (SBV)?

culicoides midges

What vector transmits schmallenberg virus (SBV)?

no treatment, but infected animals develop long-lasting immunity, and vaccines are available in some regions

What is the treatment for schmallenberg virus (SBV)?

schmallenberg virus (SBV)

What is this?

acute, often fatal viral disease (flavivirus) affecting sheep, particularly in upland areas of the British Isles and Ireland

What is louping III?

ixodes ricinus ticks

What vector transmits louping III?

up to 60%

What is the mortality rate of louping III in lambs?

1. High fever (biphasic)

2. depression

3. anorexia

What are the clinical signs of the initial stage of louping III?

1. Incoordination

2. ataxia

3. "louping" or jumping gait

4. muscle tremors

5. paralysis

6. jaw champing

7. recumbency

What are the clinical signs of the neurological stage of louping III?