CO-INFECTIONS

Because some diseases are transmittable to humans it is wise to discourage small children from kissing their pets, especially on their mouths. Equally advisable is to discourage pets from licking the face or mouth of a human. It is also prudent to encourage children to be careful with animals in petting zoos and to wash their hands after leaving (carrying disinfecting wipes is a good idea).

It is possible to have an overlap of Lyme disease symptoms with one or more tick-borne diseases such as Ehrlichiosis, Anaplasma, Babesiosis, Rocky Mtn Spotted Fever, Bartonellosis and Q Fever (Q for Query), thus increasing the difficulty of diagnosis and treatment management. The co-infections do not affect all animals.

As with Lyme disease, co-infections are a stronger possibility in animals that are in a higher tick exposure environment. For example, dogs used for hunting are definitely at an enhanced risk for multiple infections. Recent evidence indicates that veterinary care should include screening for a panel of tick-transmitted pathogens when a sick dog has a history of tick exposure in endemic areas. One veterinarian in the US reported the test results for a dog brought in; Lyme disease was found as well as 5 co-infections!

Recent molecular and serologic findings indicate that coinfection of multiple pathogens is probably more frequent than had been realized. It has also been found that dogs infected with Ehrlichia and Bartonella are more prone to nosebleeds. Further research is needed to determine how multiple infections can impact the severity of illness.

As the list of symptoms of co-infections is long, it is highly improbable that an animal at risk would have all the symptoms. Here are some further notes on the other tick-borne diseases; all can present as a single infection or as co-infections.

Rocky Mountain Spotted Fever

This disease is caused by the organism Rickettsia rickettsii when a dog tick is attached for 5 to 20 hours. It occurs mostly in the spring and summer, poses a greater risk to dogs under 4 years old and large breed dogs ( most likely to be outdoors more frequently). German Shephards may be at higher risk than other purebreds.

Clinical signs of the disease are swelling of the face and limbs, fever, depression, abdominal pain, coughing, loss of appetite, enlarged lymph nodes, pinpoint hemorrhages under the skin (called petecchiae), eye inflammation, swollen or painful joints and pneumonia. With active infection it is possible that the organs of an animals body could be affected.

It is reported that other small mammals are vulnerable but no further information is available at this time. However, cats and dogs can bring in infected ticks that could infect humans. There is no vaccine available for Rocky Mountain Spotted Fever.

Babesiosis

Caused by an organism of the genus Babesia canis or Babesia gibsoni; these species are protozoa, different from bacteria, thus requiring a different treatment protocol.

Dogs under three years of age are more susceptible although older dogs do sometimes present with anemia, loss of platelets (decreasing the blood's ability to clot) or inflammation. Greyhounds are more vulnerable than other breeds. Babesiosis, while it mainly affects red blood cells, can involve many organ systems, and can result in many complications. The disease can be mild or can lead to fatalities.

Signs to watch for are: pale gums, lethargy & weakness, labored or fast breathing, inability to produce urine or red colored urine, excessive thirst, poor appetite, jaundice (yellow coloration of the gums & eyes), fever, coughing, bloody & frothy nasal discharge, collapse, seizures or coma.

Cats are also vulnerable to Babesiosis; watch for: fever, vomiting, diarrhea, loss of appetite, weight loss, cough, breathing difficulties, depression, jaundice, enlarged lymph nodes, seizures, muscle spasm, paralysis and blindness.

Equine babesiosis (also called Equine piroplasmosis) can be caused by two species: Babesia equi (or Theileria equi) and Babesia caballi. B. equi causes more severe disease. A number of ticks can carry Babesiosis. Donkeys and mules are included in Equine Babesiosis.

Susceptibility to Babesia can be of special concern to horses involved in international trading or equestrian sports. The United States and Canada are considered to be disease free though it is endemic in South and Central America, the Caribbean, Africa, the Middle East, and Eastern and Southern Europe. Therefore, there is a risk of introduction in situations where infected and non-infected animals are together, such as equestrian events.

Severe health problems are unlikely in horses that are routinely exposed to Babesia but some infected horses can become very ill or die. Signs to watch for are: fever, swollen abdomens, constipation, colic, breathing difficulties, jaundiced mucous membranes, loss of appetite, and depression. Although the chronic form usually appears after an acute phase, clinical signs are not specific and include: loss of condition, poor exercise tolerance and slow recovery. Rare atypical forms include gastro-enteritis, broncho-pneumonia and abortions.

The disease is not known to be a problem with cattle or other ruminants in North America.

Bartonellosis

In the past Bartonellosis was called Cat Scratch Fever as it could be passed to humans through a simple scratch. Fleas as well as ticks may carry the organisms responsible.

In 1993, Bartonella vinsoni (berkhoffii) was isolated in dogs. However, because this discovery is recent, data is limited. There has been one case reported with Bartonella henselae implicated. Dogs more prone to Bartonella are those at risk in high tick exposure areas, exposure to infected cattle or heavy flea exposure. With only basic knowledge available as yet, manifestation of the disease is known to present as heart (specifically endocarditis) , lymphatic, liver and rhinitis (nose) disorders.

The parasite responsible for Bartonella in cats is mycoplasma haemofelis. Two strains of this organism have been identified; one in Ohio, the other in California. Mother cats can pass the pathogen to kittens though how that is possible, whether in utero or nursing, has not be determined. Symptoms include anemia, pale mucous membranes, poor appetite, depression, fever, weakness, enlarged spleen and jaundice. Chronically infected cats may present with intermittent fever and weight loss. The chronic stage may become a subclinical infection that recurrs after stress.

Present knowledge does not include other domestic animals as being vulnerable to Bartonella. However, in 2000, a study on Bartonella species in wild and domestic ruminants in North America, found that 49% of cattle, 90% of mule deer and 15% of elk tested positive.

Ehrlichiosis & Anaplasma

There are several Ehrlichia species that are known to infect dogs. Because Ehrlichia are rickettsial organisms they are difficult to isolate using conventional tissue cultures. Clinical diagnosis can be difficult as symptoms are not always noticeable or specific; a dog can live for years without presenting any major "bell ringing" symptoms. The organisms responsible are: Ehrlichia canis, Ehrlichia platys,Ehrlichia chaffeensis, ehrlichia ewingii, and Ehrlichia equi (Anaplasma phagocytophilum).

Worldwide, E. canis is the most significant cause of infection in dogs. There can be a wide range in the severity & duration of the illness. While animal infections can provide an awareness of the potential for infections in humans, with Ehrlichia, human patients have contributed to recognition of the manifestations in animals.

Perhaps the most notable generic symptom is that a sick dog will just not seem to be in the peak of health. The animal is depressed, (lethargic and uninterested in daily routine). There may be discharge from the eyes or nose, enlarged lymph nodes, poor appetite or possible breathing difficulties. These symptoms mark the acute stage which manifests at 8 to 20 days after infection. At this point the disease is easily treatable, fatalities are rare and spontaneous recovery may occur.

However, if these early symptoms go unnoticed the illness goes into a sub clinical stage where no symptoms are in evidence. Thus begins a five year decline in health that decimates the immune system. Treatment in this stage is not simple but remains possible.

The later chronic stage is the most difficult. While the disease can become debilitating, it can also be fatal. Dogs may present swelling, severe weight loss, nosebleeds, and/or blood disorders. The animal may be prone to vague symptoms to outright kidney failure, cancer or brain inflammation. Unfortunately, there is still little information regarding long term treatment follow-up for dogs with Ehrlichiosis.

Ehrlichiosis in cats is less well-defined, and the pattern of the development of disease is not yet well known. Present evidence indicates that three species of Ehrlichia are responsible for infection: E. risticii, E. canis, and E. phagocytophilia (Anaplasma phagocytophilum). The lack of knowledge is mainly due to the under recognition of feline tick-borne infections and the fact that cats often have a decreased development of disease, compared to other animals. However, known cases of Ehrlichiosis, such as they are, have provided some insight into symptom possibilities.

In experiments, clinical symptoms of E. risticii include fever, depression, lymph node disorders, poor appetite and diarrhea. In 2001 there were only 50 suspected or proven cases of E. canis. Of those cases, where age was reported, most were over two years of age and were domestic short hairs. Symptoms included poor appetite, lethargy, joint pain, weight loss, breathing difficulties, and swollen spleen and lymph nodes.

Because healthy cats can also test positive for Ehrlichiosis, diagnosis of a suspected case should not rely on serology, but should include clinical symptoms, testing to exclude other diseases, and monitored response to anti-rickettsial medications. It is possible for cats to be infected with more than one specie of Ehrlichiosis. Therefore it is possible that infected cats could present as a reservoir of infection for humans. Outdoor cats should be protected with a tick collar or deterrent, and be groomed frequently.

Horses are vulnerable to two species of Ehrlichiosis: Ehrlichia equi (also known as Equine Granulocytic Ehrlichiosis) and Ehrlichia risticii (also known as Equine Ehrlichial Colitis, Equine Monocytic Ehrlichiosis and/or Potomac horse Fever).

E. risticii, or Potomac horse fever, has not been reported outside of North America, often occurring in only one animal out of several on a farm. Clinical symptoms are lethargy, poor appetite, fever, ileus (intestinal obstruction), colic, diarrhea and laminitis (inflammation of the tissues inside the hoof wall). It is unlikely that the majority of these symptoms would be present. However, symptoms of intestinal obstruction is the most common of clinical finding and diarrhea develops in about 60% of infected horses.

In the early phase changes in the leukocytes of the blood are notable; leukocytes being the blood corpuscles that protect the body against micro organisms that cause disease. The severity of symptoms can vary widely. Without treatment, the mortality rate ranges from 5 to 30% as a result of toxemia. It is sometimes necessary for a horse to be euthanized due to laminitis.

Blood tests are generally not a reliable method of diagnosis. There is a recent development of a more specific diagnostic test, the Western Blot, but it may not be available in Canada. Because a definitive diagnosis may not be available, administration of the appropriate antibiotics may be an effective method of determining the infection. If E. risticii is the causative agent improvement will be noted within 12 hours. The improvement will be noticeable in temperature of the animal, upgraded attitude, feed intake and gastrointestinal sounds. If such dramatic response to the antibiotics is not present, the diagnosis and selection of antibiotic should be reconsidered.

Ehrlichia equi, now renamed as Anaplasma phagocytophilum, has been confirmed in several states, British Columbia, Sweden, Great Britain, and South America. Although horses and humans appear to be infected with strains of the same causative agent, it is not believed that direct transmission is possible from horses to humans.

The severity of clinical symptoms can vary with the age of the infected animal and the duration of illness. Younger horses may present with only a fever while some animals up to three years old may exhibit fever, depression, some swelling of limbs and lack of coordination (ataxia). Adult horses also present with fever, some loss of appetite, depression, reluctance to move, limb swelling, lesions, jaundice and petichiation. Symptoms worsen over several days and in rare situations, heart arrythmias may be present. Concurrent infectious ailments, such as a wound or respiratory problem, will be worsened with the presence of Ehrlichiosis in the system. Diagnosis is determined by the exclusion of other possible illnesses, clinical findings and blood tests.

Sheep, goats, and llamas are also at risk for infection with A. phagocytophilum in North America but little information is available.

Donkeys and mules would have the same vulnerability to Ehrlichiosis as horses. Cattle are not at risk in North America.

Q Fever

Q fever, caused by the rickettsial organism, Coxiella burnetti, does not normally cause clinical disease in animals with the possible exception of abortion in sheep and goats. Known worldwide, the disease is underreported, therefore accurate assessment is not possible. It is worth including in cooinfections because of the risk of infection to humans through animals.

Animals shed the microbe in their urine, feces, milk and particularly in birth products. The organisms resist heat, drying and many common disinfectants, allowing long term survival in soil and dust. Due to its highly infectious nature it is a serious concern on farms. Therefore all farm animals are at risk as are those who work with farm animals. Only a few contaminated organisms floating in airborne dust are all that is necessary for infection to be passed on, either to humans or other animals. It may be prudent for farm dogs to be tested prior to breeding.

Tuleremia

Tuleremia is the bacterium Francisella tularenisis, a highly contagious disease that affects 250 species, including birds, reptiles, fish, wild and domestic animals and humans. It is primarily transmitted by ticks in the adult stage, though the nymph and larval stages are also capable of transmission. Although there are two types, only Type A is found in North America. Carnivores, including dogs and cats, can be infected by eating infected carcasses such as rabbits or rodents.

Dogs are considered resistant but there is a high prevalence in dogs in endemic areas. Illness is not always apparent therefore reports of clinical signs are limited. In reported cases, disease has been self-limiting with supportive treatment. Symptoms include: nasal and eye discharge, pus lesions at the bite site, lymph node abcesses, fever, poor appetite, muscle pain, and weakness.

Cats infected with Tuleremia can experience a range of the disease, from nonapparent illness to fatal sepsis (bacteria in the blood) and death. When apparent, clinical signs may include fever, depression, lymph node abcesses, skin abcesses, muscle pain, eye disorders, mouth or tongue ulcers, intestinal disorders, liver and/or spleen enlargement, jaundice, weight loss, poor appetite, pneumonia, weakness.

Sheep infection is usually a seasonal disease reflecting the months of tick infestation. Affected sheep may islolate themselves from the flock. Death is more common in lambs (up to 15% of untreated lambs during an outbreak) and pregnant ewes. Clinical signs are fever, rigid gait, diarrhea, frequent urination, weight loss and difficulty breathing.

Cattle appear to be resistant to Tuleremia although natural infection is evident from reports of seroconversion. At present there is little data showing the true incidence of infection or knowledge of clinical signs.

Horse infection reports are also limited; though known affected animals have been highly exposed to tick infestation. Existing data gives the clinical signs as fever, difficulty breathing, lack of coordination and depression. These symptoms would likely be similar in infected donkeys or mules.

Though goats, llamas and alpacas are all vulnerable there is little data on clinical signs or findings. It can probably be assumed that infection would be possible where the more common clinical signs are apparent, ie., fever, lethargy, poor appetite, stiffness, reduced mobility or other signs that would indicate a blood infection.

Tick Paralysis

Tick Paralysis is a relatively rare ailment that can prove fatal if the attached tick is not discovered and removed. Unlike other tick-borne illnesses, Tick Paralysis is not a disease but rather, a condition created by a toxic chemical substance in affected ticks. Unlike a pathogen-caused disease, Tick Paralysis recovery begins with the removal of the affected tick. While the Rocky Mountain wood tick is the specie of concern in British Columbia and the northwest US, the American dog tick is responsible in the southeastern US, though other areas of Canada and the US are also vulnerable. Other species of ticks may be involved: the blacklegged tick, the western blacklegged tick and the lonestar tick. However, not all ticks of a particular species can cause the condition.

Because of the rarity and lack of surveillance, information is scanty. However, Tick Paralysis is a serious concern on the east coast of Australia where 100,000 pets and 10,000 cattle are affected yearly. Therefore, much information is available from Australian sources.

Tick Paralysis occurs when an animal is bit by a female tick that secretes a chemical toxin from its salivary glands. As the tick feeds (up to several days), the toxin attacks the central nervous system (neurotoxin). In approximately seven to nine days after the tick attaches symptoms can be noticed.

All animals are at risk of Tick Paralysis. Symptoms begin with lack of coordination and numbness of the legs. As the paralysis moves upwards, the body becomes relaxed, the joints easily moved. In veterinary language this is called ascending, flaccid paralysis. Eventual paralysis of the limbs will move to the chest muscles, then to the voice box. A further complication will arise if the animal breathes stomach contents into the lungs, thereby causing severe, possibly fatal, pneumonia. The toxin can also cause sudden heart failure.

Tick removal with tweezers does not pose a danger of more toxin being released into the bite site. However, it is possible for the tick to be infected with any of the other tick-borne diseases and further infection is possible. Recovery from tick paralysis requires one to 14 days, depending on severity of illness. During this recovery time the animal must be discouraged from sleeping on its' side to prevent further risk of breathing stomach contents into the lungs.

Bibliography

Journal of the American Veterinarians Association: 1990 July 1:197 (1): 64-67 "Tick parasitism and antibodies to Borrelia burdorferi in cats."

Journal of the American Veterinarians Association: 2000 April 1: 218 (7):1092-7 "Assessing the association between geographic distribution of deer ticks and seropositivity rates to various ticks-transmitted disease organisms in dogs.

Journal of the American Veterinarians Association:2000 Oct 1:217 (7): 1045-50 "Serologic confirmaitons of Ehrlichia equi and Borrelia burgdorferi infections in horses from the northeastern United States."

Journal of Infectious Diseases 2000: 181: 1069-81 "Infections with Lyme disease spirochete may linger in antibiotic-treated dogs."

Journal of Veterinarian Medical Science 1993 Dec: 55 (6): 921-4 "Serological survey for Borrelia burgdorferi infection in cattle in southern Hokkaido."

Veterinarian Rec 2000 April 22: 146(17): 497-9 "Diagnosis of Lyme Disease in two cows by the detection Borrelia burgdorferi DNA."

United States Police Canine Association: http://www.uspcak9.com

12th International Conference on Lyme Disease & Other Spirochetal & Tick Borne Disorders April 99: Lyme Disease in Dogs: Basic Research

American Veterinary Medical Association - Lyme Diseasse

Lyme Disease & Pets- http://www.lyme.org/otherdis/diseases.html

Lyme Disease- http://www.PetEducation.com

American Association of Equine Practitioners- Lyme Disease in Horses

Cornell Veterinarian- July 1992: 82 (3): 253-74 "Lyme Borreliosis in cattle and horses: a review of the literature."

Advanced Experimental Medical Biology 1995; 383: 73-82- "Experimental feline Lyme Borreliosisas a model for testing Borrelia burgdorferi vaccines."

Lyme Disease in Cats - http://www.messybeast.com/lyme.htm

World Small Animal Veterinary Association: World Congress, Vancouver 2001 "Bartonellosis: Veterinary and Human Implications" http://www.vin.com/VINDBPub/SearchPB/Proceedings/PR05000/PR00142.htm

"Feline Ehrlichiosis and Hemobartonellosis" http://www.vin.com/VINDBPub/SearchPB/Proceedings/PR05000/PR00111.htm

"Ehrlichiosis: New Developments http://www.vin.com/VINDBPub/SearchPB/Proceedings/PR05000/PR00143.htm

Tick Disease FAQ by Pam Barbe http://www.samfans.org/faq/tickfaq1.html

Rhode Island Department of Health "Lyme Disease and Pets" http://www.health.ri.gov/disease/communicable/lyme/pets.php

"Tick Borne Diseases Pose Growing Concern for Practitioners" http://http://www.donaldvaughan.com/ticks1.html

Rocky Mountain Spotted Fever Equine Granulocytic Ehrlichiosis Potomac Horse Fever Tularemia Tick Paralysis http://www.merckvetmanual.com

The Human Ehrlichiosis in the United States, features of the organism http://www.cdc.gov/search.do?action=search&queryText=human+ehrlichiosis%2C=organism&x=13&y=9

"Tick Borne Disease" by Lew Olson http://www.petcaretips.net/tick-borne-disease.html

"Tick-borne Dog Disease Tough to Spot" http://www.homeagainid.com/news/article.cfm?storyid=15446

Q Fever http://www.cdc.gov/ncidod/dvrd/qfever/

Lyme Disease in Dogs http://www.thepetcenter.com/gen/lyme.html

"Bartonellas spp. Isolated from Wild and Domestic Ruminants in North America http://www.cdc.gov/ncidod/eid/vol6no3/chang.htm

New Method for Lyme Disease Diagnostics http://www.thehorse.com/enews/7212004.html

Ehrlichial Research Laboratory http://riki-lb1.vet.ohio-state.edu/ehrlichia/background/ehrlichiaspp.php

Equine Babesiosis http://www.spc.int/rahs/Manual/Equine/BABESIOSISE.htm

Rocky Mountain Spotted Fever (search dogs + Rocky Mountain Spotted Fever) http://petplace.netscape.com/

Tularemia http://www.cvm.msu.edu/courses/mic569/docs/parasite/tularemi.htm

Tularemia Facts http://www.avma.org/pubhlth/biosecurity/tularemia_facts.asp

Return to: Your Pets and Lyme