Xenopsylla cheopis

By Jessica Sand

TAXONOMY Kingdom :Amimalia Phylum: Arthropoda Class: Insecta Order: Siphonaptera Family: Pulicoidea Genus: Xenopsylla Species: cheopis

THE ORIENTAL RAT FLEAXenopsylla cheopis is also called the oriental rat flea.

MORPHOLOGY The Oriental rat flea has no genal or pronotal

combs. This characteristic is used to differentiate Xenopsylla cheopis from other fleas.

The flea's body is about 1.5 to 4 mm long. It consists of three different regions that are common in arthropods. These regions are the head, thorax, and abdomen.

A flea's mouth is used for two purposes. The first is for squirting saliva or partly digested blood into the bite. The second is for sucking up blood from the host.

MORPHOLOGY CONT. Larvae are 4.5 mm

long and resemble white worms. They lack both eyes and legs. Each larva has fourteen bristled segments.

GEOGRAPHIC RANGEXenopsylla cheopis is thought to have originated in Egypt as a parasite of gerbils and grass rats.

It has been carried around the world by ships carrying black rats (Rattus rattus) and now has a worldwide distribution.

Also, it is frequently found on the common or brown rat (Rattus norvegicus).

DEFINITIVE HOSTS The definitive hosts of the Oriental rat

flea include rodents, primates, and occasionally humans.

The most common definitive host is the common brown rat.

INTERMEDIATE HOST There are no known intermediate hosts

of the Oriental rat flea.

LIFE CYCLE

http://www.youtube.com/watch?v=CSH0dO6pZz8&feature=related

PATHOGENESIS / CLINICAL SIGNS

Small, red bumps that are very itchy

Hives or a rash

Skins infections can result from severe

itching

Inflammation

DIAGNOSIS AND TREATMENT

A physical examination of the flea bites is sufficient for diagnosis.

When treating flea bites, the goal is to get rid of the fleas by treating the home, pets, and outside areas with insecticide to prevent reinfection.

If flea bites occur, an over-the-counter 1% hydrocortisone cream can help relieve itching.

CONTROL METHODS

Keep rodent populations under control

Use flea prevention on your pets such as topical treatments and/or flea collars

Keep floors clean by vacuuming regularly

If flea infestation occurs: Use insecticides to kill fleas in your home Wash anything and everything that has been

exposed to the fleas Sprays or bombs can be used to kill the fleas as well

PUBLIC HEALTH CONCERNS

This species can act as a vector for plague (Yersina pestis), Murine typhus (Rickettsia typhi), and also act as a host for tapeworms (Hymenolepis diminuta and Hymenolepis nana).

Xenopsylla cheopis is most famous for its role in the Black Death.

PLAGUE: INTERESTING FACTS Plague, caused by a bacterium called Yersinia pestis, is

transmitted from rodent to rodent by infected fleas.

Epidemics of plague in humans usually involve house rats and their fleas. These epidemics continue to occur in some developing countries (mostly in rural areas).

The last rat-borne epidemic in the United States occurred in Los Angeles in 1924-25.

Since then, all human plague cases in the U.S. have been sporadic cases acquired from wild rodents or their fleas or from direct contact with plague-infected animals.

RING AROUND THE ROSY! There are some people who believe that the age old nursery rhyme:

“Ring Around the Rosy” is actually a song about the bubonic plague.

Ring around the Rosy: symptoms of the plague included a rosy red rash in the shape of a ring on the skin

Probably referring to the red bumps that appear as a result of an infected flea bite

Pockets full of posies: a common belief of the time was that the plague was the result of “foul air.” To combat this, pouches were filled with sweet smelling herbs and carried around to ward off the disease.

Ashes, Ashes: the meaning of this line is not quite agreed upon, some people think it refers to the cremation of the victims of the plague and others believe it refers to a symptom of the plague that creates black patches on the skin from tissue death

We all fall down: the death rate of people infected with the plague was enormous. Many people “fell” victim to the illness.

GEOGRAPHIC RANGE

In the United States during the 1980s plague cases averaged about 18 per year. Most of the cases occurred in persons under 20 years of age. About 1 in 7 persons with plague died.

Worldwide, there are 1,000 to 2,000 cases each year.

MAP OF DISTRIBUTION OF THE PLAGUE

TRANSMISSION Plague is transmitted from animal to animal and from

animal to human by the bites of infected fleas.

Less frequently, the bacteria enter through a break in the skin by direct contact with tissue or body fluids of a plague-infected animal. For instance, the process of skinning a rabbit or other infected animal could transmit the disease.

Plague is also transmitted by the inhalation of droplets expelled by coughing, by an infected person or animal.

Person to person transmission is uncommon and has not been observed in the United States since 1924 but does occur as an important factor in plague epidemics in some developing countries.

PATHOGENESIS / CLINICAL SIGNS

There are three types of plague that can occur. They include Bubonic plague, Septicemic

plague, and Pneumonic plague.

BUBONIC PLAGUE It is the most common type of plague.

Onset of symptoms is usually 2 to 6 days after a person is exposed.

The symptoms of Bubonic plague include enlarged, tender lymph nodes (called buboes), fever, chills and severe exhaustion.

SEPTICEMIC PLAGUE A condition caused by the

invasion of bacteria into the bloodstream.

The symptoms of this type of plague include fever, chills, abdominal pain, diarrhea, vomiting, bleeding from your mouth, nose, or rectum, or under your skin, blackening and death of tissue (gangrene) in your extremities, most commonly your fingers, toes, and nose.

PNEUMONIC PLAGUE The disease finally progresses to a lung

infection called plague pneumonia, and it can be transmitted to others through the expulsion of infective respiratory droplets by coughing.

Symptoms of Pneumonic plague include fever, chills, cough and difficulty breathing, bloody sputum, rapid shock, and death.

The death rate of patients with plague pneumonia is over 50%.

DIAGNOSIS The diagnostic sign of Bubonic plague is a very

painful, swollen, and often hot-to-the touch lymph node, called a bubo.

Other symptoms include fever, extreme exhaustion, and a history of possible exposure to rodents, rodent fleas, wild rabbits, or sick or dead carnivores should lead to suspicion of plague.

There are certain criteria for laboratory tests for the diagnosis of plague. Available at:

http://www.cdc.gov/ncidod/dvbid/plague/lab-test-criteria.htm

DIAGNOSIS CONT. Specimens should be taken for

microscopic examination

Material from the affected bubo should be taken, which should contain numerous organisms.

Blood cultures should be done whenever possible. Organisms may be seen in blood smears if the patient is septicemic.

Sputum/throat smears should be taken from pneumonic plague patients and should be stained with a more specific fluorescent-antibody (FA) test.

TREATMENT Drug therapy should begin as soon as

possible after the laboratory specimens are taken.

The drugs of choice to treat plague are streptomycin or gentamycin, but a number of other antibiotics are also effective.

Those individuals who have come in contact with pneumonic plague patients should be placed under observation or given preventive antibiotic therapy, depending on the degree and timing of contact.

CONTROL AND PREVENTION

Control rat populations in both urban and rural areas

Use an effective insecticide to control rodent fleas

Eliminate food and shelter for rodents in and around your home, workplace, and recreation areas

Remove brush, rock piles, junk, and food sources (such as pet food)

Treat your pets for fleas on a regular basis

Preventative drug therapy can be used in the event that you are exposed to an infected animal or human

Preferred antibiotics are the tetracyclines, chloramphenicol, or one of the effective sulfonamides

REFERENCES http://www.nhm.ac.uk/nature-online/species-of-

the-day/scientific-advances/disease/xenopsylla-cheopis/distribution-ecology/index.html

http://animaldiversity.ummz.umich.edu/site/accounts/information/xenopsylla_cheopis.html

http://www.dpd.cdc.gov/dpdx/html/imagelibrary/A-F/Fleas/body_Fleas_il4.htm

http://www.youtube.com/watch?v=CSH0dO6pZz8&feature=related

http://www.nlm.nih.gov/medlineplus/ency/article/001329.htm

http://en.wikipedia.org/wiki/Oriental_rat_flea#Life_cycle

http://www.cdc.gov/ncidod/dvbid/plague/lab-test-criteria.htm