Archive for the ‘Tularemia’ Category

Review of Tick Attachment Time For Different Pathogens

Stephanie L. Richards, Ricky Langley, Charles S. Apperson and Elizabeth Watson 


Improvements to risk assessments are needed to enhance our understanding of tick-borne disease epidemiology.

We review tick vectors and duration of tick attachment required for pathogen transmission for the following pathogens/toxins and diseases: (1) Anaplasma phagocytophilum (anaplasmosis); (2) Babesia microti (babesiosis); (3) Borrelia burgdorferi (Lyme disease); (4) Southern tick-associated rash illness; (5) Borrelia hermsii (tick-borne relapsing fever); (6) Borrelia parkeri (tick-borne relapsing fever); (7) Borrelia turicatae (tick-borne relapsing fever); (8) Borrelia mayonii; (9) Borrelia miyamotoi; (10) Coxiella burnetii (Query fever); (11) Ehrlichia chaffeensis (ehrlichiosis); (12) Ehrlichia ewingii (ehrlichiosis); (13) Ehrlichia muris; (14) Francisella tularensis (tularemia); (15) Rickettsia 364D; (16) Rickettsia montanensis; (17) Rickettsia parkeri (American boutonneuse fever, American tick bite fever); (18) Rickettsia ricketsii (Rocky Mountain spotted fever); (19) Colorado tick fever virus (Colorado tick fever); (20) Heartland virus; (21) Powassan virus (Powassan disease); (22) tick paralysis neurotoxin; and (23) Galactose-α-1,3-galactose (Mammalian Meat Allergy-alpha-gal syndrome).

Published studies for 12 of the 23 pathogens/diseases showed tick attachment times. Reported tick attachment times varied (<1 h to seven days) between pathogen/toxin type and tick vector. Not all studies were designed to detect the duration of attachment required for transmission. Knowledge of this important aspect of vector competence is lacking and impairs risk assessment for some tick-borne pathogens.


The researchers point out that unlike mosquitoes which rely on saliva for transmission, ticks can transmit via saliva, regurgitation of gut contents, and also via the cement-like secretion used to secure itself to the host (hard ticks).  Published data on transmission times relies upon rodent studies showing 15–30 min for Powassan, anywhere from 4-96 hours for bacteria, 7–18 days for the protozoan Babesia microti, and 5-7 days for neurotoxin (Tick Paralysis). For soft ticks, attachment time of 15 sec–30 min was required for transmission of Borrelia turicata (Tick Relapsing Fever).

The challenge with these studies, and there are many, is that most placed multiple ticks on multiple rodents.  Multiple ticks may be transmitting different pathogens.  It has also been shown that ticks feeding on mice coinfected with B. microti and B. burgdorferi were twice as likely to become infected with Bb compared to B. microti, suggesting that coinfection can amplify certain pathogens – which is another reason to only use one rodent and one pathogen to separate out multiplying factors to muddy the waters.  Also, rarely do studies record the titer of both tick and host – again, making it nearly impossible to determine what’s what.  It was also noted that transmission times are unknown for many pathogens.

**And as always:  if you are the ONE person who contracted Lyme Disease in 10 minutes, all these numbers are essentially meaningless.  The frightening truth is that these numbers, along with geographical information regarding tick habitats, are often used against patients.  It is beyond time for doctors to listen, educate themselves, and treat patients with the respect they deserve – not to mention it’s time for them to treat patients clinically and not based on tests that are wrong over half the time and with the knowledge that ticks are spreading everywhere and bringing the pathogens with them. (In other words, throw the maps away!)

The review essentially gives the following transmission times for various pathogens. Again, please know these numbers are not definitive and many, many cases have proven this fact.

Take each and every tick bite seriously and don’t mess around and take a “wait and see approach.”  There is too much at stake.

Transmission Times noted in review:

Anaplasmosis: 24 hours and increased dramatically after 48-50 hours.  It is possible for it to be transmitted transovarially (from mom to baby tick) and it inhabit’s the salivary glands more frequently than the mid-gut.

Babesiosis:  Greater than 36 hours, 17% after 48 hours, and 50% after 54 hours.  Can be transmitted transovarially and transstadially (pathogen stays with tick from one stage to the next).  Ticks feeding on mice coinfected with B. microti and B. burgdorferi were twice as likely to become infected with Bb compared to B. microti.

Lyme Disease (Borrelia burgdorferi):  24 hours; however, the researchers comment that there are questions regarding previous transmission studies.  They also commented that there may be a difference in attachment time between nymphs and adult females. Transovarian transmission is unknown.

Tick Relapsing Fever (Borrelia turnicatae, B. hermsii):  15 and 30 seconds respectively.  Transovarian transmission is unknown.

Borreliosis (Borrelia mayonii):  24 hours.  Transovarian transmission is unknown.

Borrelia myamotoi Disease:  24 hours.  Transovarial transmission occurs.

Tularemia (Francisella tularensis):  Not assessed.  Can be transmitted mechanically by deer flies, horse flies, mosquitoes, aerosol/ingestion when processing/eating infected animal tissues.  Can be transmitted transtadially and transovarially.

Rocky Mountain Spotted Fever (Rickettsia rickettsii):  10-20 hours.  Can be transmitted transovarially.

Heartland Virus:  Not assessed.  Can be transmitted transovarially and transstadially.

Powassan Virus:  15 Minutes; however, it is possible it was sooner since the first they checked for transmission was 15 minutes.  Can be transmitted transovarially.

Tick Paralysis (Neurotoxin):  2-6 days.

Alpha Gal/Mammalian Meat Allergy (Galactose-a-1,3-Galactose):  Not assessed.  Transovarian transmission is unknown.

For more on transmission times, please read:



Of Rabbits and Men


Tularemia is known as a rabbit disease which is spread to those who handle them including hunters and cooks; however, at the recent Lyme Disease Association 17th Annual Conference on Lyme and Tick-Borne Diseases, Timothy Lepore, MD, FACS, surgeon at Nantucket Cottage Hospital, explained that it is also a disease of those who work with the land such as landscapers and farmers, as well as those who get bit by a tick. There are cases reported in every state but Hawaii, and many other wild and domestic animals can be infected. The highest rates of infection are in Arkansas.

Tularemia first appeared in the United States in Massachusetts in 1937 after importing 30,000 to 40,000 rabbits per year from Europe. Importing came to an end in 1947.
Francisella tularensis, a gram negative, aerobic, pleomorphic, highly persistent intracellular pathogen, spread via the lymphatic system can cause fever, chills, headache, myalgia, extreme fatigue, glandular (swollen glands), oropharyngeal (sore throat, nausea, vomiting and diarrhea, abdominal pain and intestinal ulcerations), conjunctivitis, pneumonic (dry cough, respiratory difficulty and chest pain), ulceroglandular (skin ulcer at infection site) and can be septic and lethal. Symptoms typically develop within three or four days of inoculation but can take up to 10 days.

Tests: Tests for Tularemia are not widely available but direct examination of biopsy specimens or secretions by fluorescent antibody or Gram or histochemical stains are often helpful. F. tularensis can also be demonstrated microscopically with fluorescent-labeled antibodies. Antibodies are not typically present in the first ten days after exposure. Patient samples should come from sputum or pharyngeal washings, as the organism is not present in large numbers in blood. Polymerase chain reaction (PCR) tests can also be utilized. It is imperative that lab personnel take strong precautions as it is quite easy to become infected.

Treatment: Antibiotic therapy with Gentamicin (5mg/kg/day, IM or IV) or streptomycin (1 gm twice daily, IM). The recommended treatment period is 10 days. In vitro susceptibility studies indicate that quinolones and fluoroquinolones are also effective against F. tularensis, thus providing an additional option for physicians. Tetracyclines and chloramphenicol can also be used, but a higher rate of relapse is associated with these agents, as they are bacteriostatic rather than bactericidal. Thus, it is recommended that treatment with these medications be extended to 2-3 weeks. If treatment is initiated quickly the mortality rate for tularemia is around 1-2%; however, one-third of untreated patients will die, usually from pneumonia, meningitis or peritonitis.
Transmission: Transmission can occur through the skin or mucous membranes when handling infected animals as well as through tick bite, contact with fluids from infected deer flies, mosquitoes or ticks, handling or eating undercooked rabbit, drinking contaminated water, inhaling dust from contaminated soil, and handling contaminated pelts or paws of animals. It can also be inhaled from infected hay, grain, or soil. Dr. Lepore had patients who contracted it from their pet dog who shook rain water on them after chewing on a dead rabbit, as well as from folks eating road kill, a person who held sick animals, and a gentleman who slept with his pet bunny.
Tularemia, in aerosol form, is considered a possible bioterrorist agent that if inhaled would cause severe respiratory illness. It was studied in Japan through 1945, the USA through the 60’s, and Russia is believed to have strains resistant to antibiotics and vaccines. An aerosol release in a high population would result in febrile illness in 3-5 days followed by pleuropneumonitis and systemic infection with illness persisting for weeks with relapses. The WHO estimates that an aerosol dispersal of 50 kg of F. tularensis over an area with 5 million people would result in 25,000 incapacitating casualties including 19,000 deaths.

In a mass casualty situation – treat with oral agents for 14 days using Doxycycline (adults 100mg by mouth twice a day, children under 45kg 2.2 mg/kg by mouth twice daily) or Ciprofloxacin (adults 500mg, by mouth twice a day, children 15mg/kg by mouth twice a day).

Those performing autopsies should avoid bone sawing or any procedure likely to cause aerosolization and exposed people should wash with soap and water. In environmental contaminations use a 10% bleach solution for spraying and cleaning using alcohol 10 minutes after using bleach. There have been no reports of human to human transmission.