Ticks and Tick vectored diseases

Tick Prevention

* Topical Products - Frontline, Advantix, etc * Tick Collars - Amitraz * Avoiding high risk areas *Trails used by wildlife/deer

True insects

- 3 pairs of legs (6 legs in adult stage) - 3 main body parts (head, thorax, abdomen) -Incomplete or complete metamorphosis possible - Egg, larva, pupa, adult - Egg, nymph, adult - Lice, fleas, mosquitoes, flies, etc.

Arachnids

- 4 pairs of legs (8 legs in adult stage) - 2 main body parts (head, body) - Usually have egg, larva, nymph, adult stages in life cycle - Larva often only has 6 legs, nymph like small adult -Ticks, mites, (spiders too!)

Tick Larva

- 6 legged - Feed once

Tick Nymph

- 8 legged - Feeds 1-2 times

Tick Paralysis

- Acute, rapid, progressive - Unable to move in 24-48 hours - No spinal reflexes, but full pain sensation - From neurotoxin released by gravid, female - Dermacenter or Ixodes species - Starts 4-9 days after attachment - Causes death from respiratory paralysis if untreated - When tick is removed Improvement in 24 hours, normal in 48

Tick Bites

- After hatching must find and attach to favorite hosts - Will "quest" by finding tall grass, branch, etc and wait for host - Sense host with organs on first legs - Will grab on and move cranially or dorsally until appropriate attachment site is found - Feeding usually lasts for several days

Hard ticks *Dermacentor veriabilis

- American Dog Tick - It is the most important vector of the Rocky Mountain spotted fever rickettsia in the eastern U.S. - and is also able to transmit the bacteria which causes tularemia (hunter's disease).

Anaplasma

- Anaplasma phagocytophilum - Infects a variety of animals and people - Morulae in eosinophils in cats - Transmitted by Ixodes ticks

2 Arthropod Classes

- Arachnids - True insects

Hard Ticks * Rhipecephalus sanguineus

- Brown Dog Tick - feeds on dogs during all three life stages, but drops off and reattaches during each stage - Will infest buildings - Carries Babesia, Ehrlichia, Hepatozoon, Rickettsia

Tick Identification

- Can be very challenging - Males and unengorged adult females the easiest - Size, shape, color, markings, host and location on host can be used

RMSF * Clinical and subclinical

- Clinical and subclinical disease in dogs, naturally acquired immunity possible - Fever, cutaneous lesions, edema (scrotal and limb), petechiae, neurological signs, etc. - Thrombocytopenia, mild leukopenia * Rapidly responds to antibiotics - Tetracyclines, Enrofloxacin, etc

Lyme Disease * Detection

- Detection of antibodies to OspC may be used to screen for active host infection - Per Idexx Santa Rosa has exceptionally high # of test positive dogs - Snap 3DX/4DX tests for antibody to C6 peptide- more accurate test to differentiate vaccinated and infected dogs - Test result needs to be interpreted in context of clinical signs - Positive test may lead to further evaluations of kidney function, more specific lyme testing, and consider antibiotics

Tick Removal (Don't)

- Do not use Vaseline, fingernail polish, matches/fire, rubbing alcohol or similar substances - Won't work and may trigger increased regurgitation into patient

Ticks General features

- Dorsally compressed, leathery bodies - Head has penetrating, anchoring structures - Partial or complete covering by scutum - Feed on blood and vector many diseases - Second only to Mosquitoes as disease vectors

Ehrlichiosis * diagnosis

- ELISA, PCR - indirect FA test- serum antibodies- can take 7- 28 days to show up - Tetracyclines drug of choice

Anaplasma * clinical signs

- Fever - Headache - Muscle pain - Malaise - Chills - Nausea / Abdominal pain - Cough - Confusion - Rash (rare with anaplasmosis)

RMSF * clinical signs

- Fever - Rash (occurs 2-5 days after fever, may be absent in some cases; see below) - Headache - Nausea - Vomiting - Abdominal pain (may mimic appendicitis or other causes of acute abdominal pain) - Muscle pain - Lack of appetite - Conjunctival injection (red eyes)

Cytauxzoonosis Clinical signs

- Fever, dyspnea, icterus, dehydration, pallor - Lethargy to comatose - Once RBC parasitemia then poor prognosis - Attempts to treat this pathogen have met with little success. - IV Imidocarb

3 host life cycle

- Finally, many ticks feed on three hosts, one during each life stage. - These ticks drop off and reattach to a new host during each life stage, until finally the adult females lay their batch of eggs. - In each case, the fed adult stage is terminal, that is, after laying one batch of eggs the female dies, and after the male has reproduced, he dies as well

Tick Groups

- Hard and Soft Ticks * Ixodid family * Argasid family

Ixodid family

- Hard ticks - Hard scutum that covers all of male, 1/3 of female dorsum - Males usually smaller depending on engorgment - May feed on 1,2 or 3 hosts throughout life cycle

Tick Egg

- Lay in protected places - Cracks, under leaves, etc

Hard ticks * Amblyomma americanum

- Lone Star Tick White - spot on apex of scutum on females - Southern US, midwest, east coast - Painful bite

Ehrlichiosis * clinical signs

- Lymphadenomegaly - Polyarthritis - Acute, chronic and sublicnical forms - Depression, lethargy, mild wt loss, anorexia, - Neurological signs- meningitis (ataxia, etc), ocular signs occasionally - Most common have to do with thrombocytopenia - Can lead to petechia, hemorrhage, epistaxis, retinal bleeds, anemia - Can be difficult to differentiate from IMT

2 host life cycle

- Other ticks feed on two hosts during their lives. - This type of tick feeds and remains on the first host during the larval and nymph life stages, and then drops off and attaches to a different host as an adult for its final blood meal. The adult female then drops off after feeding to lay eggs

Hard ticks * Dermacentor occidentalis

- Pacific Coast Tick - This is one of the most widely distributed ticks in California

Lyme Disease *info

- People: annular skin lesions, polyarthritis, meningitis, chronic disease - Percentage of dogs developing clinical disease is very low (5% - 10%) despite high seroprevalence - Fever, polyarthritis common in dogs - Can also cause renal disease! - Natural disease not described in cats - Dogs, cats, people are incidental hosts, but disease still considered zoonotic - ELISA, indirect FA common diagnostic tests

Soft Ticks * Argas sanchezi and Argas persicus

- Poultry ticks - Shasta down to Kern county - Ticks can survive in empty poultry housing for years

Lyme Disease

- Principle vector = hard ticks, Ixodes scapularis/pacificus - Difference in the populations of Ixodes scapularis influence the prevalence of disease - environmental factors such as soil, forestation, feeding habits (hosts), etc. - Reptiles not competent reservoir, lizards posses borreliacidal substance in blood. - In people 85% of cases in east coast states from MA to VA, 10% upper Midwest (MN, WI), 4 % N California

Cytauxzoonosis

- Protozoal infection - Vectored by Dermacenter and Amblyoma Tick is the definitive host! - Infects cats southern US - Bobcat reservoir - Protozoa invades macrophages - Forms cyst like structure called schizont - Protozoa divides, enlarging schizont - Can get so big it occludes blood vessels - When schizont ruptures, stage called merozoite released and parasitize RBCs

Tick Bites

- Range from unnoticed to painful and irritiating - Saliva can vector disease or cause "tick paralysis" - Ticks will bite/attach, engorge and then fall off - Require moderate temp and moderate to high humidity to develop - Digest, molt and grow off of host - Most live in dirt/vegetation - All outside other than Brown Dog Tick

Tick Removal (Do)

- Remove ticks as soon as found - Even if feeding may prevent disease transmission - Grab mouthparts with tweezers, hemostat, etc - Slowly, steadily pull out - Do not jerk - Do not crush body May force contents into patient - Do not twist - Remove mouthparts if not completely removed by pulling

Rocky Mountain Spotted Fever

- Rickettsia rickettsii - Tick-borne, rickettsial disease of Americas, affects dogs and people - Important zoonotic disease - High % of human rickettsial disease - Throughout contiguous US, most common in SE - Dermacentor ticks main vector, also Amblyomma ticks

Hard ticks * Dermacentor andersoni

- Rocky Mountain Wood Tick - This tick is well known as a vector of the Rocky Mountain spotted fever rickettsia in the northwestern U.S. and Canada, the Colorado tick fever virus, and the bacteria which causes tularemia

Lyme disease natural host * Blacklegged Tick Nymph Size

- Size of a poppy seed - Transmits most cases of disease because they are so difficult to detect - Seeks a blood meal from mid-May to mid-July - Male and Female Adult Blacklegged Tick Feed and mate on large animals in the fall or early spring - After feeding, females lay eggs, then die - Ticks that did not feed or mate go dormant

Lyme Disease * Borrelia burgdorferi

- Small spirochetes - Cannot survive as free-living organisms in environment - Most commonly diagnosed vector borne disease of people in the US - Discovered 1975 in Lyme Connecticut -Transmission requires tick attachment 24-48h - Host immune reactions likely prevent many infections even after exposure

Argasid family

- Soft ticks - No scutum - Mouthparts seen from dorsal aspect - Rarely seen on pets in our area

One host life cycle

- Some ticks feed on only one host throughout all three life stages. - This type of tick remains on one host during the larval and nymphal stages, until they become adults, and females drop off the host after feeding to lay their batch of eggs

Soft Ticks * Otobius megnini

- Spinose ear tick - Nymph and Larval stages parasitic - Found in ear of hosts - Irritating - Seen on otoscope and ear cytology exams - Arid southwest US

Hard ticks * Boophilus annulatus

- Texas cattle fever tick - North American tick - One-host - Eradicated from US - Reportable, enters from Mexico

Ehrlichiosis

- Tick-transmitted gram negative obligate intracellular bacteria - Primary vector is Rhipicephalus sanguineus, can be Ixodes - 24- 48 hours minimum feeding time for tick - Zoonotic - Multisystemic disorder, caused by variety of ehrlichial species E canis, also disease caused by ewingii, risticii, and platys - Infect primarily leukocytes (WBC), thrombocytes (platelets)

Lyme Disease

- Vaccine not universally recommended, does not replace tick control measures - OspA is antigen expressed by bacteria in ticks, OspC is antigen expressed by bacteria in dogs - Recombinant and killed virus vaccines available - Not all have OspC protective effect - Consider vaccine in high risk dogs, needs to be annual - Debate about giving vaccine to dogs who are ELISA positive - May contribute to immune complexes that cause kidney damage

Lyme Disease Signs & Symptoms

- Weeks to months after illness onset - Fatigue - Chronic arthritis - Nervous system problems

Hard ticks * Ixodes pacificus

- Western Black Legged Tick - It is the putative vector of the Lyme disease spirochete and the equine granulocytic ehrlichiosis rickettsia in California - Humans bitten by these ticks may notice intense inflammation at the site of the bite which may be slow to heal

Adult Ticks

- Will feed many times _ Avoid weather extremes - Will live for years - Will live for months between feedings

Soft Ticks * Ornithodorus coriaceus

- the Pajahuello tick - For humans, the bite of this tick is notoriously painful, - San Diego to Humboldt county

Ticks - Life Stages

4 life stages * Egg * Larva * Nymph *Adult Ticks

Some human diseases

of current interest in the United States caused by tick-borne pathogens include Lyme disease, ehrlichiosis, babesiosis, rocky mountain spotted fever, tularemia, and tick-borne relapsing fever.

Ticks

transmit the widest variety of pathogens of any blood sucking arthropod, including bacteria, rickettsia, protozoa, and viruses.