Flying Squirrel Associated Typhus

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Flying Squirrel Associated Typhus

Postby Joan » Tue Sep 21, 2004 10:51 pm

The CDC has published several studies of humans who have contacted typhus after being in contact with flying squirrels. A 2003 article can be viewed at:

A better understanding of typhus can be found at: ... 9/159b.jsp

The little known cause of Ann Frank's death in the Bergen-Belsen concentration camp was typhus:

I am going to provide a summary of a prepublication article on flying squirrel associated typhus provided to me at the Andulusia Flyer Conference by Tom Risch Ph.D. Tom requested that I get this information to flyer owners. The article was written by Mary G. Reynolds et al. at the Viral and Rickettsial Zoonoses Branch, Centers for Disease Control and Prevention, Atlanta.

Epidemic typhus is a potentially severe, but treatable disease once thought to cycle exclusively between humans and body lice. In the mid-1970, it was discovered that southern flying squirrels were a reservoir for the typhus pathogen, Rickettsia prowazekii.

No other animal is known to be a host species. In the past 25 years, 39 cases of flying squirrel suspected typhus in humans has been reported. Most occur during the winter months in flyer trappers and individuals removing nest debris from attics or nest sites. Individuals involved in inspection of red-cockaded woodpecker nest are at risk as flying squirrels frequently usurp their tree cavities.

Between 1962 and 1975, investigators demonstrated the typhus pathogen in southern flying squirrels captured in Florida and Virginia. In the decade after this discovery. a number of cases of typhus were documented among persons living in eastern and southern USA, all of whom had some type of contact with flyers.

In human transmission, body lice become infected while obtaining a blood meal from an infected individual and subsequently shed organisms in their feces before the lice themselves die of the infection. Humans then become infected by direct contact with the louse feces via a mucous membrane or dermal abrasion (usually from scratching irritated skin), or by inhaling infectious material (feces). The typhus incubation period is usually 12-14 days before early symptoms appear e.g. headache, chills, fever, nausea, and muscle aches. Fever is often higher in the evenings and does not get better with aspirin. Another common sign is a flat, red rash (typically on the trunk of the body and spreading to the limbs). Later signs are photophobia (bright light hurting the eyes), stupor, vomiting and leg pain. Severe complications are meningitis, encephalitis, pneumonia, renal failure, or gangrene of the extremities due to microvascular damage.

Typhus can also establish latency and reappear years or decades later in a recrudescent form called Brill-Zinsser disease. These symptoms are often milder, but not always less severe that the initial infection. Fatalities are rare.

Effective treatment consists of tetracycline therapy. Laboratory testing is the only definitive way to diagnosis typhus.

Flying Squirrel Reservoirs:

The isolation of the typhus organism in flying squirrels was discovered while studies were being done on the ecology of Rocky Mountain Spotted Fever in Virginia and Florida in the 1970s. Most cases of typhus in humans have been reported from states within the range of the southern flying squirrel. Studies on the epizootiology of infection in wild populations of flyers indicate that the organism responsible for typhus exhibits a stable pattern of infection in animal populations rather than massive epidemic cycles. Flyers populations experience seasonal fluctuations in infection intensity with peak s during the winter and spring months. most new infections were noted in pups experiencing their first cold season.

During these months, there is a corresponding peak in the organisms that transmit typhus. Flyers carry the Rickettsia for 2 to 3 weeks before becoming ill. Flyers are hosts to 2 of the principle vectors of typhus ... fleas and lice.

Of the 39 cases of flyer-associated typhus, all but one case in California came from the Southern flyers range and most occurred during the winter. While many individuals were seriously ill and most hospitalized, no deaths occurred.


The mechanism of transmission from flyer to humans remain speculative. It is thought that the transmission is by inhalation or by skin or mucous membrane inoculation of infected infectious louse or flea feces. Histories of close contact with flyers or flyer nesting material in the days prior to illness onset exist in all cases.
These contact generally involve removal of flyers from a home or other building, or cleaning of an infested area.

The risk of infection to wildlife biologists and others exposed to flyers appear to be greatest during the colder months of the year and in handling flyers and nest material. Wildlife biologists engaged in red-cockaded woodpecker reintroduction are also at risk as are persons who maintain captive animals.

Prevention and Avoidance:

An individual may reduce his probability of developing the disease by protective measures (e.g. wearing gloves, eye protection. mask) when engaging in risky activity with flyers.

Typhus can be a severe disease and persons who are unable to take tetracycline because of pregnancy or allergic reactions are recommended to avoid handling flyers and flyer nests, or to rigidly adhere to the use of protective barrier equipment. This is also recommended for immunocompromised or immunosuppressed individuals.

The End

All this being said, 39 cases in 25 years isn't much. I do think that we can advise individuals who write in about ridding their attics, etc. of flyers, to wear a dust mask.

Chuck said he is still going to kiss me on the mouth ;-)

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