ECTOPARASITES Fleas

Flea Biology and Ecology Order: Siphonaptera Hind legs are adapted for jumping Adults are exclusively blood suckers (most are mobile, but some are attached) The “attached” species are like the ticks, they put their mouthparts in host and stays there for a while. Unfed adults live a long time, but they can’t really leave the area where they are so they just hang out waiting for a blood meal, and they are very active when looking. Somewhat host specific (not as host specific as lice), and it varies with species.

Life Cycle Holometabolous Egg  Larvae  Pupa  Adult –18 days to 20 months Eggs (3-18 at one time in several batches) Larvae need high humidity –9-15 days optimal (up to 200 days) Pupa –7 days to 1 year Adult –Live up to 4 years.

Flea Life Cycle

Important Flea Species Xenopsylla cheopis (Oriental Rat flea) - primary urban plague vector [also X. brasiliensis in Africa, India and S. America - more rural] Pulex irritans (Human flea) - occasional epidemic plague vector Nosopsyllus fasciatus (Northern Rat flea - epidemic plague, murine typhus Diamanus montanus (Common Ground Squirrel flea) - endemic plague vector in Western US Primary pest species - Ctenocephalides felis, C. canis, P. irritans

Importance (1) Irritation and Discomfort (1)Dipylidium caninum (double-paired dog tapeworm) (2)Tunga Penetrans (3) Annoyance from bites (2) Vectors of Disease Murine Typhus Bubonic Plague (3) Primary pest of an animal that has a home.

Cestodes Dipylidium caninum (dog tapeworm) Transmission –Tapeworm eggs in feces –Larval fleas ingest eggs –Eggs penetrate gut wall of flea enter body cavity. –Remain trapped until flea becomes an adult –Encapsulate and become cysticercoids (infective) –Dog, cat, or human ingest flea and become infected

Tunga Penetrans Chigoe flea, jigger flea Distribution Does not transmit any disease. Small size, and very compressed. Females burrow into skin. What are the “Sand Fleas?”

Murine Typhus Also called, Flea Typhus, Endemic Typhus Pathogen - Rickettsia typhi (bacteria) Vector - Xenopsylla cheopis (oriental rat flea) Reservoir – Roof rat and Norway rat Distribution – USA, Mexico, Europe, Australia, Port areas. Transmission – flea feces

Plague History – long and brutal Pathogen – A gram negative coccobacillus Vector – Xenopsylla cheopis (oriental rat flea) Reservoir- Rattus rattus (the roof rat) Distribution - Worldwide –Urban –Rural Transmission – regurgitation, crushing the flea Signs and symptoms – “bobos” Forms of the plague (2 common forms) –Primary bubonic –Primary pneumonic Treatment

History of the Black Death Named after the “bobos” that are produced cases each year. Originated in China Introduced to the U.S. at port cities, San Francisco. Occurs 4-5 times every years. 200 million lives lost and counting… Minor disease in U.S. (N. Mex cases/year avg is 12)

Known and probable foci of plague. Plague is now largely focal in distribution. It spreads rapidly in conditions of war and other catastrophes, e.g. earthquakes. Epidemics still occur from time to time.

Source: Dennis DT Plague as an emerging disease. Emerging Infections 2. Scheld WM, Craig WA and Hughes JM, Eds. ASM Press, Washington DC.

60% of total 25% of total Source: Dennis DT Plague as an emerging disease. Emerging Infections 2. Scheld WM, Craig WA and Hughes JM, Eds. ASM Press, Washington DC. 15% of total

Source: Dennis DT Plague as an emerging disease. Emerging Infections 2. Scheld WM, Craig WA and Hughes JM, Eds. ASM Press, Washington DC.

Urban Plague (1)Pathogen: Yersinia pestis (2)Reservoir: Domestic rodents, especially Rattus rattus (the roof rat), reservoir is rodents. (3)Vector: Xenopsylla cheopis (oriental rat flea) – the primary vector. (4)The ease with which it becomes “blocked” (5) Feeds readily on humans and rodents (6) Abundance near human habitations

Plague

Rural Plague (1)Pathogen: Yersinia pestis (2) Vector: There are numerous flea species that can vector the disease. (3)Numerous reservoirs which include wild rodents: filed mice, deer mice, pack rats, chipmunks, ground squirrels, tree squirrels, prairie dogs, and cottontails. (4) Pets may bring fleas into homes. (5) Cats are highly susceptible.

Plague

Rock Squirrel

The typical sign of the most common form of human plague is a swollen and very tender lymph gland, accompanied by pain. The swollen gland is called a "bubo." Bubonic plague should be suspected when a person develops a swollen gland, fever, chills, headache, and extreme exhaustion, and has a history of possible exposure to infected rodents, rabbits, or fleas. A person usually becomes ill with bubonic plague 2 to 6 days after being infected. Signs and Symptoms

Plague

Forms of human plague: Primary bubonic or zoonotic form, inflammation of lymph glands, initially from rodent to human via flea vector Primary pneumonic or demic form, human to human via infective respiratory droplets Fleas leave dead body (rat or human) and move to next available host. Primary flea vectors of plague to humans are species of Xenopsylla, X. cheopis

Treatment The disease is treatable with antibiotics. very rapid development. Can be misdiagnosed Treat effectively early It is when the disease goes pneumonic that a high mortality rate occurs (90%).

Flea Control Sanitation Sanitation – environmental clean up is important to destroying harborage for eggs, larvae, pupae and adults Chemical Insecticides Chemical Insecticides – apply to cats and dogs, spray rodent infested environments; flea collars often not very effective (incomplete coverage); topical application of insecticides absorbed through the skin Insect Growth Regulators (IGRs) Insect Growth Regulators (IGRs) – topical application on animals; fumigation of affected rooms, etc.; ovicidal as well as insecticidal