Cat scratch disease (felinosis) - symptoms and treatment
Cat scratch disease (cat scratch fever, felinosis, or regional nonbacterial lymphadenitis) is an acute bacterial zoonotic infection transmitted primarily from cats. It is characterized by regional lymphadenitis (inflammation of the lymph nodes), skin rash, and sometimes damage to the eyes, nervous system, and internal organs.[1]
The cause of the disease is infection with the bacterium Bartonella henselae, which has been isolated from humans and mammals and is a small pleomorphic, facultative, gram-negative and intracellular bacillus.
Sources of infection
Cats are a natural reservoir and carrier of B. henselae, and the animals themselves are not affected by it. In a number of studies conducted in the USA, 28% of examined cats had antibodies against the causative bacterium, and of these, 56% of kittens younger than one year and 34% of cats one year and older were immune to the bacillus. The study also showed that stray cats (61%) had B. henselae in their blood much more often than domestic cats (21%).[2]
Kittens younger than 12 months are 15 times more likely to transmit the infection than adult cats due to the presence of B. henselae bacteria in the blood and a greater tendency to scratch.
Transmission of infection between cats occurs through the bite of the cat flea Ctenocephalides felis or ingestion of their waste products. Therefore, people who have at least one kitten with fleas in their home are 29 times more likely to become infected with bacillus than those whose animals did not have fleas in their fur.[3]
Dogs are also a source of infection, but much less frequently than cats - only 5% of cases.[4] Isolated cases of the disease occurring in human contact with guinea pigs, rabbits and monkeys have also been reported.[1]
Among other things, the role of Ixodes ricinus (dog tick) in the transmission of infection has been proven, which often attacks people.[5] A case of familial infection with Bartonella due to their bites has been described.[6]
Transmission to humans from cat flea bites and from person to person has not been confirmed.[2]
Ways of transmission of infection:
- Scratches . 75-90% of patients with felinosis shortly before the onset of the disease noted superficial skin trauma during contact with a cat. The fact is that fleas, while on an animal, excrete excrement that contains bacteria. When a cat scratches its skin (for example, by scratching), its claw becomes contaminated with waste material, which can then transmit the infection to humans when it is injured.[1]
- Bites and salivation on injured skin are associated with the presence of bacteria in the saliva of animals.[1]
The prevalence of the disease in the world and in the Russian Federation is not known. The incidence in the United States among outpatients is approximately 9.3 cases per 100,000 people per year, with up to 20,000 new cases reported annually.[7] Approximately 70-90% of cases occur during the fall and early winter months. It is assumed that seasonality is associated with an increase in the birth rate of kittens in mid-summer and with an increase in flea infestation.[8]
At-risk groups
The disease is more common in people under 18 years of age (55 to 80% of cases). This is due to the fact that it is children and teenagers who most often play with kittens.[9]
It is also worth noting that the disease is more common in men than in women, in a ratio of 3:2. One hypothesis to explain the higher incidence among males is a tendency to play rougher with kittens and cats and therefore have an increased risk of biting and scratching.[1]
History of discovery
Bartonella was first discovered by Peruvian microbiologist Alberto Barton in 1905, who discovered the bacterium now called Bartonella bacilliformis in the red blood cells of patients with Bartonellosis, and in 1909 announced the discovery of this infectious agent to the world.
In addition to human erythrocytes, the favorite breeding ground for Bartonella are the endothelial cells of the vascular wall. In any case, Bartonella reproduces only intracellularly.
Although the clinical manifestations of cat scratch disease (“la maladie des griffes de chat”, as the French called it) have been known for more than a century, the symptom complex of this disease was first identified as an independent nosological entity only in 1950. And even after that, it took more than 40 years to find the causative agent of this disease!
According to all criteria (epidemiological, clinical and morphological), Bartonella henselae , which is currently considered a firmly proven fact.
Of all the diseases caused by Bartonella in humans (see list above), cat scratch disease is the most common. In the United States alone, more than 25 thousand cases of this disease are recorded annually. In Russia the numbers are approximately the same.
What it is?
In simple terms, cat scratch disease is an acute or chronic infectious disease that develops after being scratched or bitten by an infected cat. In medicine, this pathology has several other names: felinosis, benign lymphoreticulosis, Mollaret granuloma.
For the first time, felinosis was described independently by 2 scientists - R. Debre and P. Mollare - in the middle of the 20th century. At first it was believed that the disease was of a viral nature, but in 1963, scientists from Russia - V.I. Chervonskaya, A.Yu. Bekleshov and I.I. Terskikh - a pathogen was isolated, which turned out to be a bacterium of the rickettsia group - Rochalimaea henselae.
Treatment
For people with a normal immune system, local therapy (warming the affected lymph node in the absence of suppuration!) and symptomatic treatment are usually sufficient.
As a rule, it is sufficient to prescribe (and then only if necessary) antipyretic and mild painkillers - usually from the NSAID group.
Most patients with mild to moderate disease do not require antibiotics. However, people who are immunocompromised, particularly those with HIV infection, are usually prescribed antibiotics.
If the doctor nevertheless decides to prescribe antibacterial treatment to the patient (and this, I repeat, is necessary only in rare cases in people with a normal immune system), then azithromycin (a first-line drug) or doxycycline with rifampicin is usually used.
In patients with HIV infection with bacteremia (detection of Bartonella henselae in the blood), treatment can be more complex and often very long (from several weeks to several months).
Patients with atypical forms of felinosis also require a special approach (with the exception of granulomatous conjunctivitis/oculoglandular Parinaud syndrome, which is treated as standard).
In cases where the patient has CNS damage (encephalitis, meningitis, etc.), neuroretinitis, granulomatous hepatitis and splenitis, a combination of drugs (usually doxycycline with rifampicin in adults or rifampicin with azithromycin/biseptol in children) is required for a long period (1-2 month). But this decision can only be made by an experienced doctor.
If a lymph node suppurates, it may need to be drained (suction of its contents with a syringe).
Atypical form
When infectious agents come into contact with the mucous membrane of the eye, there is a high risk of developing conjunctivitis. Symptoms in case of contact with skin:
- fever;
- the appearance of ulcers;
- suppuration of injuries;
- After healing, scars form.
This form of felinosis occurs in 10% of cases. It is usually diagnosed in children, as well as the elderly (people whose body reactivity is reduced). The duration of the disease is from 6 to 8 weeks.
Clinical picture
Incubation period. It varies from 3 to 10 days, but in some cases it can last up to 1.5 months.
Initial period
At the site of a healed scratch or bite, a primary affect often appears in the form of reddish papules, which do not cause significant concern to the patient and often go unnoticed.
High period
Later, papules can fester, ulcerate and become covered with crusts, after which no scars remain after rejection. 2-3 weeks after the onset of the primary affect, regional lymphadenitis develops, most often in the armpits and neck, less often in the groin and femoral areas. In 80% of cases, an enlargement of one lymph node is noted. Sometimes the lymph nodes acquire significant sizes; upon palpation they are slightly painful and dense. The phenomena of periadenitis are not observed. Symptoms of intoxication appear in the form of increased body temperature, malaise, headache, and decreased appetite. The duration of the temperature reaction with manifestations of intoxication varies from 1 to 3 weeks. In some cases, a polymorphic allergic rash on the skin, micropolylymphadenitis, and enlargement of the liver and spleen may occur.
Convalescence period
It is characterized by the disappearance of signs of intoxication, gradual resorption, sclerosis or suppuration of the lymph nodes, followed by their opening.
Felinosis can also occur in atypical forms. One of them manifests itself in the form of unilateral conjunctivitis with the formation of ulcers and nodules on the conjunctiva and enlargement of the parotid and submandibular lymph nodes. In rare cases, neuroretinitis occurs, usually unilateral, manifested by swelling of the optic disc, the formation of star-shaped spots and nodules on the retina, and angiomatous changes under it. At the same time, visual acuity is completely preserved. In the presence of granulomatous changes in the liver, hepatic purpura develops.
Manifestations from the musculoskeletal system
If just a few years ago the involvement of the musculoskeletal system in the process was considered uncharacteristic for cat scratch disease, it has now been proven that these manifestations are very typical and occur in more than 10% of patients.
Thus, severe and prolonged muscle pain occurs in 5.8% of patients, and the average duration of myalgia is more than 1 month!
Joint pain caused by visible damage to the joint (i.e., arthritis, which is accompanied by redness, swelling and pain in the joint), or joint pain without visible changes in the disturbing painful joint (arthralgia) occur in 5.5% of patients, more often in women .
At the same time, cat scratch disease is characterized by damage to large and medium-sized joints, the pain lasts a long time (more than 1.5-2 months), in half of the patients with joint pain, the pain is of moderate or severe intensity.
Remember what was said earlier: Bartonella is a genetically shortened version of Brucella, and for brucellosis, joint damage is the main and, perhaps, the most characteristic sign of the disease! It was here, in the damage to the joints, that the relationship between these two bacteria manifested itself.
In a small proportion of patients, symptoms of cat scratch disease may persist for more than a year. Occasionally (in 1% of patients) tendonitis and even osteomyelitis occur. The risk of involvement of the musculoskeletal system in the process decreases sharply in patients over 20 years of age.
Differential diagnosis
Usually, the doctor has to differentiate felinosis from other diseases with unilateral enlargement of lymph nodes: banal purulent lymphadenitis, enlargement of lymph nodes with extrapulmonary tuberculosis, tularemia, plague, syphilis, brucellosis, toxoplasmosis, lymphomas and other tumors, as well as a number of other diseases that a competent person should know about doctor.
Of course, in some cases, the presence of a cat scratch, on the contrary, does not always help the doctor, since almost every second family has cats and they scratch often, and not all people with cat scratches develop felinosis, and not another similar disease from the list above. Then specific laboratory diagnostic methods come to the aid of the doctor.
Pathogenesis
The pathogen enters the human body through damaged skin and sometimes mucous membranes (scratches caused by cat claws or their bites). In half of the cases, papules form at the site of its introduction, which subsequently suppurate. From the portal of infection, rickettsiae disseminate lymphogenously to regional lymph nodes. Under their influence, inflammatory infiltrates with hyperplasia of reticular cells are formed in the lymph nodes, and subsequently granulomas resembling brucellosis, as well as star-shaped abscesses with the formation of fistulas. Subsequently, regression of the inflammatory process with sclerosis of the lymph nodes is possible. During hematogenous dissemination, rickettsiae enter various parenchymal organs, where similar granulomas are formed. Pathogen toxins and tissue breakdown products cause the development of intoxication and allergic reactions.
Complications
When Bartonella, which causes felinosis, spreads through the blood to various internal organs, the following may occur:
- pleurisy;
- myocarditis;
- spleen abscess;
- osteomyelitis;
- arthritis;
- atypical pneumonia.
The bacterium can also cause significant blood complications, consisting of a decrease in various blood cells:
- platelets (thrombitopenic purpura);
- red blood cells (hemolytic anemia);
- eosinophilic leukocytes (eosinophilia);
- leukocytes (leukoclastic vasculitis).
