Date sent: Wed, 27 Dec 2000 CFS in Dogs and Cats Source: Comparative Immunology, Microbiology And Infectious Disease Vol. 24, #3, pp. 57-70 Date: July 2001 Preprint: December 5, 2000 URL: http://www.geocities.com/cfsindogsandcats/ There are no tables in the electronic version (yet). Figs. 1-5: http://www.geocities.com/cfsindogsandcats/figure_1.jpg http://www.geocities.com/cfsindogsandcats/figure_2.jpg http://www.geocities.com/cfsindogsandcats/figure_3.jpg http://www.geocities.com/cfsindogsandcats/figure_4.jpg http://www.geocities.com/cfsindogsandcats/figure_5.jpg Ref: Comparative Immunology, Microbiology And Infectious Diseases: http://www.apimall.com/apinet/comimmicindi.html http://www.elsevier.nl/locate/cimid The author just published a paper on 'CFS in Horses' in the above journal (COMP. IMMUNOL. MICROB. 24: (1) 57-70 JAN 2001). See: http://www.geocities.com/cfsinhorses/ http://www.elsevier.nl/cgi-bin/cas/tree/store/cimid/cas_sub/browse/browse.c gi?year=2001&volume=24&issue=1&aid=354 Chronic fatigue syndrome (CFS) in 15 dogs and cats with specific biochemical and microbiological anomalies ---------------------------------------------------------------------------- Walter Tarello, veterinary surgeon, C.P. 42, I-06061 Castiglione del Lago Perugia, Italy, tarello@iol.it Abstract A great deal of controversy and speculation surrounds the etiology of Chronic Fatigue Syndrome (CFS) in human patients and the existance of a similar illness in animals. To evaluate the association with a presumptive staphilococcal infection and bacteremia, 7 dogs and 8 cats diagnosed with CFS (2 meeting the CDC working case definition) were submitted to rapid blood cultures and fresh blood smears investigations. Nine out of 15 blood cultures proved Staph-positive and 4 isolates were specified as S. xilosus (3) and S. intermedius (1). The presence of micrococci-like organisms in the blood was of common observation among these subjects, in association with fatigue/pain-related symptoms and biochemical abnormalities suggestive of a myopathy. Following treatment with a low dosage arsenical drug (thiacetarsamide sodium, Caparsolate, iv., 0.1 ml/kg/day) all patients experienced complete remission. Micrococci disappeared from the blood at post-treatment controls made 10-30 days later. The outcomes were compared with those of 5 healthy controls and 5 'sick with other illness' patients showing significant difference. Resume De nombreuses speculations et discussions entourent l'etioologie du Syndrome de Fatigue Chronique chez l'homme et l'existance meme d'une maladie semblable chez les animaux. Afin d'evaluer la possible association avec une infection chronique avec bacteriemie, 7 chiens et 8 chats avec un diagnostic de CFS (2 sujets correspondant a la definition humaine pour cette maladie) ont ete soumis a hemocultures et a la recherche microscopique directe de germes dans le sang. Neuf hemocultures sur 15 furent positives pour Staphilococcus spp. et 4 isolations ont ete identifiees pour S. xilosus (3) et S. intermedius. Chez tous les sujets examines, des bacteries types micrococciques ont ete trouvees sur les globules rouges, et leur presence etait associee aux symptomes de fatigue/douleur et a des anomalies biochimiques suggerant une myopathie. Ces microrganismes ont disparu apres le traitement avec un medicament arsenical, le thiacetarsamide sodium, utilise en faible dosage (0.1 ml/Kg/jour, iv.) pour 2 jours, et qui eu comme resultat la complete et durable guerison du syndrome chez tous les 15 animaux. Les resultats ont ete compare avec ceux de deux groupes de controle de 5 animaux 'sains' et 5 'autrement malades', qui etaient assez diferents mais semblables entre eux. Key Words Chronic Fatigue Syndrome (CFS); Fatigue; Staphilococcus; Micrococci; Muscular diseases; Dog; Cat; Arsenic; Thiacetarsamide sodium; Zoonosis. Mots cles Syndrome de Fatigue Chronique (CFS); Fatigue; Staphilococcus; Micrococci; Maladies musculaires; Chien; Chat; Arsenic; Thiacetarsamide sodium; Zoonose. Introduction Outbreaks and sporadic cases of a human disease with an apparent infective onset, currently called Chronic Fatigue Syndrome (CFS) or Myalgic Encephalomyelitis (ME), have occured on numerous occasions since the 1948 ('Icelandic disease') [9]. The causes, diagnosis and treatment of this condition remain controversial. Besides a debilitating fatigue unrestored by rest, common symptoms of CFS include impaired short term memory and concentration, recurrent sore throats, muscle and joint pain, sleep disturbances and adenopathy [63]. During the past decade, substantial evidence has been generated to support the existance of a CFS-like illness among animals [9, 18, 64, 65]. Although Chronic Fatigue Syndrome has never been clinically reported in dogs and cats, an epidemiological study indicate that a remarkable number (97%) of patients with CFS have animal contacts and that 75% of these pets appear sick or abnormal [32]. Two recent articles describe CFS among horses: as with the disease in humans, equine fatigue syndrome is associated with long-term exhaustion, difficult treatment and immune dysfunctions [69, 81]. Little is known about the syndrome in animals and therefore, since it appear that CFS could be a zoonosis, informations generated from studies upon animals may be useful to human researches. Initial epidemiological studies failed to identify a peculiar virus associated with clinical manifestations of chronic fatigue/chronic pain disorders [41, 57, 86]. More recently, several species of toxin-producing staphylococci have been cultured from humans affected by similar conditions [15,26, 60]. During 1993, in a attempt to verify a possible correlation with a chronic bacterial infection, 15 canine and feline cases out of 117 diagnosed with CFS, were submitted to blood cultures and biochemical studies. The primary purpose of this study was to describe the frequency of certain biochemical and microbiological anomalies that in association with clinical features led to a diagnosis of CFS. Additional objective was to determine how the syndrome was responsive to an arsenical drug, thiacetarsamide sodium (Caparsolate, Abbott Laboratories) given intravenously in low dosage, as previously observed in horses [81] and inferred from The Merck Index [82]. Material And Methods The medical records of 8 dogs and 7 cats from Aosta Valley (nord-west Italy) diagnosed with Chronic Fatigue Syndrome during 1993 were studied retrospectively. Information evaluated included history, presenting complaints, clinical signs, results of biochemical (creatine-kinase activity, serum magnesium) and microbiological examinations (blood culture, identification), treatment and response to therapy. Symptoms an signs were collected into 7 groups (Table II). 'Asthenia/lethargy' included prolonged fatigue, difficulty to rise, lack of liveliness, resistance to play and to perform normal activities, postexertional malaise and unrefreshing sleep. 'Anorexia/poor appetite' included any diminution of appetite, from slight (+) to complete (+++), lasting more than 3 days. 'Pharingitis/sore throat' included sore throat, difficulties in swallowing and/or breathing and partial to complete weakening of voice. 'Weight loss' was defined on the basis of spontaneous owner's report and/or physical examination. 'Muscular pain' included evident lamentations during walking or jumping and soft-tissue pain at moderate palpation. 'Neurologic dysfunctions' included somnolence, photophobia, shivering, seizures, depression, affective disorders, mood abnormalities and reduced cognitive ability. 'Lymph-adenopathy' was defined on the basis of a macroscopic enlargement of cervical sub-mandibular lymph nodes. Light microscopic evaluation of fresh blood smears stained with May-Grunwald-Giemsa was performed in each case at first inspection, and repeated 10-30 days after therapy with sodium thiacetarsamide in low dosage (0.1 ml/Kg/day, iv., for 2 days). This drug was given as first choice medicament, following observation of its strikingly efficacy in some equine CFS cases which had relapsed after standard therapies with antibiotics, anti-helmintics and steroids [81]. The fifteen similar canine and feline CFS cases here described, were all submitted to rapid blood-cultures (1-2 minutes for sterile sampling, insemination and incubation at 37 deg C) carried out on Columbia plates under CO_2 enriched atmosphere. The sterile conditions needed were obtained with a laminary-flux hood (Mini Securitas, PBI). All isolates were subject to Gram stain and Catalase test and four were speciated using the API Staph method (bioMerieux). An antibiogram was also performed on the isolate from cat #109 (Table I) following subculture into Muller-Hinton plate : the activities of 100 mgr. of thiacetarsamide sodium (20 mgr. of pure arsenic) and of 8 antibiotics were evaluated and compared. In order to assess the risk of contamination, ten animals non diagnosed with CFS were submited to similar blood-cultures: 4 healthy dogs, 2 cats with kidney failure, 1 cat with haemobartonellosis, 1 dog affected by parvovirosis, 1 dog with intoxication and, also, an healthy cat (#66, Table I and II) diagnosed with CFS and successfully treated 4 months before. Results The clinical signs and physical examination findings (Table II), in association with the biochemical results suggestive of a polimyositis (Table I) led to a diagnosis of CFS in all 15 patients. Asthenia and lethargy, anorexia and neurologic dysfunctions were the symptoms more frequently observed in the animals and were mostly reported by their owners. Pharingitis, weight loss, muscular pain and lymphadenopathy were recorded particularly during the visit. All animals were positive to at least three of the seven symptoms & signs cathegories, with prevalence of asthenia & lethargy (16/16), anorexia/poor appetite (16/16), followed by neurologic dysfunctions (13/16), pharingitis/sore throat (9/16), weight loss (8/16), muscular pain (6/16) and lymphadenopathy (3/16). Rectal temperature was higher than 39 deg C in 4 cats and 2 dogs. Two animals (dog #157 and cat #189) fulfilled the current criteria for CFS diagnosis in human medicine [63]: 1. the presence of clinically evaluated, persistent chronic fatigue; and 2. the concurrent occurence of the following symptoms, all of which have persisted during 6 or more consecutive months: sore throat; tender cervical or axillary lymph nodes; muscle pain and/or multijoint pain; unrefreshing sleep; and postexertional malaise lasting more than 24 hours. The method used to establish the presence of these symptoms was based on spontaneous reporting by the owners, accompanyied by complete physical examination and muscular function biochemical screening (CK and Magnesium). According to the current human criteria for diagnosis of CFS, the remaining 13 cases would have to be defined as Idiopathic Chronic Fatigue, because their clinically (and biochemically) evaluated chronic fatigue, with related symptoms, lasted <6 months. The reasons for failing to meet the criteria was partially due to precocious diagnosis and treatment. Furthermore, the CDC classification is intended only for human subjects [30, 63]. Investigations involved also a musculo-skeletal laboratory test panel: Creatine kinase (CK) activity and serum Magnesium. At rest, CK values were higher than normal references (10-75 IU/L)[89] in all dogs and cats examined, ranging from 101.4 IU/L (dog #122) to 983 IU/L (cat #48) IU/L (Table I). Contemporary, serum Magnesium below the normal range (1.5-22 mEq/L) was observed in 9 out of 15 cases (Table I), all diseased for >1 month. These abnormalities were consistent with a polimyositis and clinically associated with fatigue/pain symptoms. The incidence of the breeds and of the ages of animals sampled was not significantly different from the usual practice profile and apparently did not influence the findings. A peculiar aspect of this group of animals, not in common with 2 groups of respectively 'healthy' and 'sick with other illnesses' subjects, was the unusual and constant presence of micrococci-like organisms, sized 0.3-0.5 mm, scattered on the outer surfaces of red blood cells (RBCs) in fresh blood smears examined before treatment (Fig.1, 3). The percentage of RBCs affected varyed from 5% (dog #92) to 60% (cat #48) in absence of haemolysis and signs of regeneration (Howell-Jolly bodies, reticolocytes). No other typical canine and feline blood parasite were ever noticed [34]. Concomitantly, blood cultures performed proved Staph-positive in 9 out of 15 cases, requiring 2-3 days for bacterial growth in CO2 enriched atmosphere. Colonies were small, white or grey-pearl and made little if any detectable haemolysis (Fig 2). All isolates appeared as gram-positive (Fig. 4) and catalase-positive cocci, so the strains were expected to be staphilococci. Representative colonies from 4 isolates (Table I) were submitted to speciation and gave 3 very good identification (99.5%) of Staphilococcus xilosus (dog #122, #157 and cat #109) and 1 good identification (98.6%) of Staphilococcus intermedius (cat #189). All these strains produced acid from mannitol. A sub-culture onto Muller-Hinton agar plate from cat #109 isolate underwent antibiogram and produced the following results: 4 antibiotics had no activity (gentamycin, kanamycin, sulpha-trimethoprim and streptomycin), 4 antibiotics had partial activity (amoxacillin, ofloxacin, cephalexin and chloramphenicol) and 100 mgr of sodium thiacetarsamide showed the larger halo of ihnibition. After specific therapy based on sodium thiacetarsamide in low dosage (Caparsolate, 0.1 ml/Kg/day, iv., for 2 days) all animals diagnosed with CFS experience rapid and complete remission in 2-10 days. Improvement of health status was particularly evident during the 24 hours following the first intravenous injection. Initial disappearing symptoms were 'Anorexia/poor appetite', 'Pharingitis/Sore throat' and fever. No adverse or side effects were ever noticed. In all cases, clinical checks made between 10 and 30 days after treatment confirmed complete remission of symptoms and lack of recurrences. Contemporary, blood smears of controls proved always negative for micrococci. Following abruptly onset of CFS, a rooming cat of this study (cat #67), was well feed and maintained at rest in a warm cage without any pharmacological treatment for 40 days, in order to verify the spontaneous variations of serum CK and Magnesium levels. At the onset of the CFS-like illness, CK acitvity was hight (209.8 IU/L) and serum magnesium was within the ranges (1.9 mEq/L). Symptoms are described in Table II. Forty days later cat #67 was still sick, CK activity still hight (122.4 IU/L) and serum magnesium was low (1.3 mEq/L). After specific treatment and complete remission, both values returned within the normal ranges and cat #67 was given in adoption. A similar control on the maintenance of biochemical abnormalities was also done in cat #66, characterized by gradual onset of the illness. Ten days prior diagnosis and treatment the animal was examined and found to have mild symptoms (somnolence and balance dysfunction), moderate rise of CK activity (82 IU/L) and 25% of RBCs carrying micrococci. At the second visit, 10 days later, the health status was worsening (anorexia, lethargy and fever) accompanyied by higher CK activity (315.6 IU/L) and low serum magnesium (1.1 mEq/L). Micrococci in fresh blood smears were still present (25-30%) and a blood culture proved positive for Staphilococcus sp. (gram-positive and catalase-positive cocci) : cat #66 was treated as usual and experienced complete remission. Four months later, a clinical control confirmed the lack of CFS-related symptoms. CK activity (10 IU/L) and serum magnesium (2.0 mEq/L) at rest were normals, a blood culture resulted negative and repeated fresh blood films were micrococci-free. Discussion A disease in dogs and cats characterized by clinically evaluated chronic fatigue, constant presence of micrococci in the blood and 60% Staph-positive blood cultures, found complete remission after intravenous treatment with low dosage sodium thiacetarsamide (Caparsolate, 0.1 ml/Kg/day for 2 days), a trivalent organic arsenical, used as single drug. Four out of 9 Staphilococcus isolates were specified as S. xilosus (3) and S. intermedius (1). Diagnosis of Chronic Fatigue Syndrome (CFS) was made in all 15 cases, based upon the fatigue-related symptoms, the biochemical abnormalities evocative of a neuromuscular disorder (high CK activity, low serum magnesium) and the presence of bacteria in the blood similar to those previously observed in association with some CFS equine cases [81]. In absence of a specific test, a diagnosis of CFS in human medicine is currently done by exclusion of other known fatigue-related diseases and by complicance with a clinical definition [26, 30, 63]. In the present study, exclusion of alternative problems which may produce chronic fatigue/pain disorders (heartworm disease, babesiosis, ehrlichiosis, malnutrition, senescence, endocrinopathies, haemobartonellosis; FIV and FeLV in cats), was carefully done in all subjects referred as having CFS. During blood smears examination, particular attention was devoted to differentiate micrococci from Haemobartonella felis in cats and Haemobartonella canis in dogs (Fig. 5). These rickettsial pleomorphic organisms have typical shape ( short rod or coccus, sometimes associated in small chains of 2-4 elements), colour (blue or purple red) and size (0.3-1.5 mm) apparently different from those of micrococci [34]. Curiously, dog #157 and cat #189 fulfilled also the CDC current criteria for diagnosis of CFS in people, although this clinical definition is intended only for human purposes [63]. During the last 10 years, CFS sufferers have frequently reported anecdotal observations of strange diseases or dysfunctions in their pets [18, 32, 64, 65], but clinical descriptions of the disease are hard to find in the veterinary literature [69]. The 15 animal cases here described apparently matched the clinical picture of CFS in humans [9] and horses [81], and shared common biochemical and microbiological abnormalities (Table I), some of which -recovery of coagulase- negative staphilococci [26], high CK [5, 68] and low magnesium levels [22, 27, 36] - are analogous to those recorded in some humans with CFS. The present report introduces also the interesting feature of the striking effectiveness of an arsenical compound, sodium thiacetarsamide, mentioned in the Merck Index [82] and others ancient sources [19,71, 76] as helpful in the past for vaguely similar diseases. The unexpected presence of micrococci-like bacteria adhering to the external surface of many red blood cells, in percentage varying from 5% to 60%, was a common feature in all patients (Fig. 1, 3). These bacteria were similar to those previously observed in horses diagnosed with CFS [81] and their finding led to necessity of performing blood cultures and biochemical identifications. There is no direct evidence that they cause the disease but, apparently, their presence was linked to the condition, beeing the only remarkable haematological difference between: a. pre- and post-thiacetarsamide treatment in subjects with CFS, b. healthy and 'chonically fatigued' animals, and c. 'sick with other illness' and 'chronically fatigued' dogs and cats. In fact, all fresh blood smears taken from 4 healthy dogs and one healthy cat (formerly sick with CFS) of control, resulted micrococci-free and their blood cultures were negative. Similarly, blood cultures from 4 cats and 1 dog 'sick with other illness', in a second control group, resulted negative and their blood smears appeared micrococci-free. In contrast with these findings, 9 out of 15 patients diagnosed with CFS produced Staph-positive blood cultures (Fig 2) and 3 out of 4 identificated germs were coagulase-negative staphilococci (CNS), all mannitol-fermentig. The hallmark of this group was the notable presence of micrococci in the blood, in association with pain/fatigue symptoms, high CK acitivity and, in 9/16 cases, low serum magnesium. Taken togheter, these results apparently exclude a risk of contamination of the Columbia's plaates during procedure and seems to confirm the bacterial nature of the micrococci-like organisms observed in the blood of the reported cases (Fig 1, 3). It could therefore be suggested that their presence may be used as a coadjutor tool in the diagnosis of CFS in dogs and cats. Similar conclusions raise also from human researches on the subject, particularly from studies of Dr. Luther Lindner, pathologist on the faculty of Texas A&M University: preliminary evidences indicates that a newly recognised Human Blood Bacterium (HBB) is usually present in high number in the blood of patients with CFS or multiple sclerosis, and that a reduction in these bacteria is associated with clinical improvement and an increase corresponds with increased symptoms. Furthermore, there is no evidence that this bacteria can be completely eliminated using the standard FDA-approved antibiotics. Review from human literature [83] shows increasing incidence and severity of bacteremias due to CNS during the last 20 years. Currently, the definition of 'true bacteremia' is given by one positive blood culture in association with a clinical picture compatible with infection, both in human [83] and in veterinary [58] medicine. The pathogenicity of coagulase-negative staphilococci (CNS) and their involvement in some kinds of human and animal diseases is nowaday acknowledged [43]. Although CNS remain the most frequent contaminants, with 58-83% of positive blood cultures, the mortality associated with true CNS bacteremia in human patients varies between 4.9 and 28% in United States and Europe [83]. Emerging antibiotic resistance in CNS ensure their expansion: 85.7% of these bacteria are methicillin-resistant and their prevalence continues to increase among all infections [31]. Recently, in Canada, Usa and Latin America, the major change in antimicrobial resistance was found to be an increase in oxacillin-resistance in both S. aureus and CNS strains recovered from bloodstream infections [24]. Furthermore, vancomycin and oxacillin do not synergise against 1/3 of methicillin-resistant CNS strains, thus they do not produce therapeutics benefits [25]. A recent study shows that 30 Staphilococcus xilosus strains isolates from artisanal Italian salami were multiresistant and displayed at least three antibiotic-resistances each [56]. Comparatively, in this animal study 4 antibiotics (gentamycin, kanamycin, sulpha-trimethoprim and streptomycin) produced no activity against a mannitol-fermenting Staphilococcus xilosus strain recovered from cat #109, and 4 others antibiotics showed partial activity (amoxacillin, ofloxacin, cephalexin and chloramphenicol). Surprisingly enough, 100 mgr. (1 drop) of thiacetarsamide sodium produced the largest halo of inhibition. In vitro and in vivo comparisons between sodium thiacetarsamide and current antibiotics was not among the purposes of this study. Nonetheless, it is intriguing to note that the striking degree of antimicrobial action of this drug against a representative Staph-strain isolate from a cat with CFS was associated with the disparution of symptoms and of micrococci from the blood, after a short-term and low-dosage therapy with the same agent. These findings are coherent with an underlying staphilococcal infection responsive to sodium thiacetarsamide. This drug was used as first choice treatment in all patients diagnosed with CFS, following previous personal observations of in vivo multiple antibiotic-resistance [81]. Is is notable that these 15 patients obtained a rapid improvement and complete remission from a chronic state of exhaustion with a drug that is considered obsolete and used today in higher dosages (4-fold) only against heart-worm disease in dogs. In the past, a similar condition in cats, called 'staggering disease', proved to be resistant to several anti-microbials and corticosteroids, and most cats deteriorates, died, or had to put to sleep after several months [49]. Retrospective bibliographical research revealed that CFS-like diseases have already been described in dogs and cats during the last twenty years with many different names: 'staggering disease' [49], 'episodic weakness' [11], 'idiopathic polimyositis' [62] and 'idiopathic meningo-encephalomyelitis' [79]. No truly effective therapy has ever been indicated. These observations might argue that the activity of sodium thiacetarsamide is of particular value against a CFS-like illness in animals. As a matter of fact, similar arsenical preparations have been used until '70s 'tonics' for horses and dogs [19, 71] and as 'general stimulant in nervous diseases' [82]. The Merck Index [82] list several arsenical compounds as useful against 'general debility', however no relationship has ever been made with underlying chronic bacterial infections or with the presence of micrococci in the blood. Today, arsenic is often considered synonymous with 'poison' and 'cancer'. Interestingly, arsenic is probably the oldest known chemical agent used to treat cancer [84] and is an essential element to some species including humans [4, 29], but the specific biochemical reason for its importance has not yet been found [84]. The total mass of this element in an average person (70 Kg) is 18 mg [29] and, based on animal studies, a calculated arsenic requirement for humans is 12 to 25 micrograms per day. Seefoods contribute the most arsenic to the diet [28] but also grains and cereals products [84]. Recent studies indicate that low serum arsenic is correlated with Central Nervous System disorders, vascular diseases and certain forms of cancer in humans [84] and death during lactation and skeletal muscles disorders in goats [73]. The anti-cancer effect of some arsenical compounds, such as arsenic trioxide and melarsoprol, is today rediscovered, particularly against acute promyelocitic leukemia [37, 77], B-cell leukemia [47], myeloid leukemia [38, 66], multiple myeloma [70] and others myeloproliferative [2] and lymphoproliferative malignancies [78, 92], even associated with human retrovirus infection [40]. Fatigue is the most common symptom of these conditions. Surprisingly, a noticeable rate of lymphoproliferative disorders and leukemia have already been described in cats with CFS-resembling illness owned by CFS patients [32] and in people with severe CFS [41]. On the other hand, gram-positive cocci were found to be responsible for 66% of microbiologically documented febrile episodes in elderly japanese leukemic patients [44]. The mechanism of growth inhibition of arsenic trioxide is due to induction of apoptosis [77] but also to preferential vascular shutdown in the tumor tissue, leading to massive necrosis in the central part of a solid tumor, as recently described in mice [53]. Melarsoprol, also, has showed to produce high levels of apoptosis against solid cancer cells, both in vivo and in vitro, suggesting a novel therapeutic approach to breast and prostate cancer [48] and to neuroblastoma [1]. Inhibition of production of superoxide and of inflammatory mediators, such as Tumor Necrosis Factor, are obtained at low concentration of arsenic [50], and these effects are dependant upon both the oxidative state of the arsenic and on the physical state of the arsenic compounds [51]. The effectiveness of AS(2)O(3) has also recently been demonstrated in vitro against cancer cell lines of gastric [90], head and neck [74], oesophageal [75] and epithelial origin [91]. During the last twenty years the arsenicals have fallen into disrepute in veterinary medicine and have been replaced by more modern alternatives. Organic arsenicals were still used in human medicine in the mid-1950 in the treatment of certain nutritional disturbances, rheumatism and asthma [82], all conditions apparently overlapping the current description of CFS. The antibacterial action of arsenical drugs is acknowledged in both human [42] and veterinary medicine [82], dating back several centuries. Hippocrates is said to have used arsenic sulfide as a remedy for ulcers, anemia and skin diseases. Paul Ehrlich, the father of chemotharapy produced in 1907 the first clinically effective "magic bullet" against shyphilis, an arsenic compound called Salvarsan, and provided the stimulus for the development of more than 8000 arsenical compounds, examined as possible pharmaceuticals until 1950 [42]. >From 1900 to 1948, period during which these compounds were largely used in medicine, no epidemic outbreaks of CFS/ME-like syndromes were reported in humans, apart from the Los Angeles County General Hospital epidemic (1938), thought to be caused by polio. A similar illness, called Neurasthenia, was described since 1869 [7] and recognised as a pathological condition during the late XIX century [8]. Then, it vanished during the first decade of the XX century [23, 33, 87] contemporary with the advent of arsenicals chemotherapics both in human (Atoxil, 1905) and in veterinary medicine [19]: was it a real concidence ? In this report, 9 out of 15 patients had 'pharingitis/sore throat'. This is also a frequent symptom in human CFS sufferers and considered an important concurrent criteria for diagnosis [63]. Upper respiratory infections are frequently sustained by Staphilococci [45]. The therapeutic efficacy of arsenic on various respiratory tract illness is acknowledged in both human [72] and veterinary medicine [39]. Evidence is available that drinking sulphurous-arsenical-ferruginous waters have a therapeutic effect on aspecific phlogosis of the upper respiratory tract, significantly decreasing the bacterial layer and increasing the secretory portion of immunoglobulin A [55]. Recent works has shown also that particular concentrations of iron and arsenic in solution inhibit bacterial growth in mixed cultures of thermophilic bacteria [10]. The isolation of 3 Staphilococcus xilosus strains (very good identification: 99.5%) seems to confirm recent advances in human research that implicates a possible causative role of coagulase-negative bacteria in chronic pain/fatigue conditions [15,16,60,61], as well as in CFS [26]. A recent microbiology research has showed that 89% of patients with chronic muscle pain had multiple carriage of coagulase-negative staphilococci (CNS) strains which produced membrane damaging toxins meanwhile the healthy controls had none [15]. There was no clinical evidence of overt infection, but the chronic muscle pain patients had 23 versus 9 isolates/10 subjects compared with the controls. There was also a higher incidence of carriage of two or more CNS strains in the muscle pain patients group [15]. The muscle pain subjects carried staphilococci which produced d-like membrane damaging toxins, whereas controls subjects did not carry toxin-producing strains. The carriage of membrane-damaging toxins was strongly correlated with increases in symptom severity, palpitations, fatigue, pain and weakness. Changes in urinary excretion patterns where detected, including an increase in tyrosine output suggestive of an active proteolysis [59,60]. Such proteolysis may secondly stimulate the reactivation of viruses of the herpes family [61], frequently implicated in the past as primary causative agents of CFS [13,41] but eventually discharged [57, 86]. The mechanism of action of trivalent organic arsenicals has been related to their effects on sulphydryl-rich proteins - these compounds are known to be effective binders of -SH univalent radical - including enzymes and toxins that affect protein tyrosine phosphorylation [21]. This observation is in agreement with the finding that energy production in CFS patients is dysregulated by a possible inhibition of oxidative phosphorylation [59] in association with increased tyrosine urinary excretion, indicative of an active proteolysis [60]. In this study, serum biochemical results were consistent with a polimyositis or a neuromuscular disorder. In fact, creatine kinase activity was significantly higher than the reference range (10-75 IU/L) in all the subjects examined at rest, and the serum Magnesium was below the normal range in 6 out of 7 dogs and in 3 out of 8 cats (Table I). There are some disorders, such as myocardial infarction, in which these anomalies are customary, but these seldom develop in small animals [14]. Causes of increased plasma CK activity are primarily associated in pets with skeletal muscle damage and Central Nervous System disorders [14]. In a rooming cat of this study diagnosed with CFS and untreated (cat #67, Table I and II), hight levels of CK activity were still observed 40 days later. CK is the most sensitive indicator of muscle damage available and persistent CK activity indicates persistence of the underlying disorder [14]. Following specific treatment and complete physical remission of cat #67, CK values returned within the normal ranges. Similar controls were also done in cat #66, characterized by gradual onset of the illness: ten days before diagnosis and treatment, mild symptoms were associated with a moderate rise of CK activity (82 IU/L). At the second visit, the health status was worsening accompanyied by higher CK activity (315.6 IU/L). Micrococci were present in the blood and blood-culture proved positive for Staphilococcus spp. Cat #66 was treated as usual and experienced complete remission. Four months later, a control confirmed that CK actvity (10 IU/L) was again between the ranges. Fresh blood smears and blood culture resulted bacteria-negative. Although no electromyographic or histophatological findings could be produced to support a diagnosis of primary neuromuscular disease, it is acknowledged that hight CK levels are associated with mitochondrial myopathy in dogs [11] and idiopathic polymyositis in cats and dogs [62]. Elevated CK values are to be observed occasionally in human patients with CFS, particularly in the acute phase of the illness and in the most affected people [5, 68]. Similarly, red blood cell magnesium levels were found significantly decreased in a group of 32 patients with ME/CFS in 1991 [22]. These observation was confirmed by others [36] and led to some therapy trials with intravenously or orally administered magnesium [20, 27, 80] that have found no or limited utility [9]. Such symptomatics treatments cannot be successful, as the disease is apparently not caused by primary minerals or vitamins deficiencies [16]. Evidences are available of secondary and acquired immune dysfunctions in CFS patients. For this reason the disease is also known as Chronic Fatigue and Immune Dysfunction Syndrome (CFIDS). Low immunoglobulin levels [46, 54, 67], reduced number and activity of the Natural Killer (NK) cells [88], enhanced autoimmunity [6, 9], hight interleukin-2 levels [17], low CD4/CD8 ratio [13] and, in some cases, CD4 count below 500/mm3 [41] are findings that make the disease a true acquired immune deficiency sydrome. Immuno-deficiency can result from many infectious agents (virus, protozoa, bacteria) toxins, neoplasia or severe trauma [12]. Toxin-secreting staphilococci are among these agents. In fact, some of them produce a group of proteins called superantigens, which are toxins characterized by the capacity of stimulating a large number of T-cells simultaneously [35] Superantingens bind directly to the MHC class II molecules on the antigen-presenting cell and crosslink the cell with T-cells expressing certain Vb-chains on their receptors, leading to a polyclonal T-cell activation and high interleukin-2 levels secretion. This mechanism can induce autoimmunity, stimulating the growth and active reproduction of that small number of lymphocytes that do not recognise the 'self'. Such aspecific activation lead also to immune-deficiency: certain T-cells subsets vigorously proliferate and finally die, leaving an open door to specific aetiologic agents [35]. Apparently, such a picture is superposable on the immune dysfunctions description reported in human CFS literature: reduction of particular T-cell sub-populations, high interleukin-2 levels and autoimmunity [9, 41]. Surprisingly enough, a recent in vitro study show that an arsenical drug, sodium arsenite, reduces proliferation of human activated T-cells by inhibition of the secretion of interleukin-2 [85]. Staphylococcal superantigens are toxins involved in the pathogenesis of systemic diseases such as Toxic Shock Syndrome and Kawasaki syndrome, which are resistant in vivo to antibiotics [52]. Similarly, there is no evidence of any curative and resolving antibiotic treatment for CFS [16] and Staphylococci recently found in CFS patients produced a significant amount of membrane-damaging toxins, d- and/or 'horse' hemolysins, whereas those isolated from an ideal musculo-skeletal, symptom-free control group did not [15]. Although toxin production couldn't be evaluated, this animal study seem to confirm such staphylococcal implication (S. xylosus, S. intermedius) in a CFS-like illness in dogs and cats. The presence of S. xilosus strains was relevant also among the species identified in human patients with chronic muscle pain [15]. Of these, 86,4 % were colonised (nose or genital tract) by two or more CNS strains, and 52,3% by three or more staphylococcal strains [15]. Furthermore, vaccination with a staphilococcal toxoid produced significant improvement in 50% of a group of sweden patients with fibromyalgia/chronic fatigue syndrome [3], supporting the results obtained by the australians scientists [26]. Conclusions It is notable that symptoms, serochemical evidences and microbiological findings observed in 7 dogs and 8 cats diagnosed with CFS are not in contrast with similar characteristics of the syndrome emerging from recent human researches on the topic [3, 5, 6, 15, 16, 22, 26, 30, 36, 55, 57, 60, 61, 63, 68, 84, 85, 86] meanwhile the striking responsiveness to an arsenical drug do not differ from the results obtained in ancient times against vaguely resembling-CFS veterinary [19, 71, 76, 81, 82] and human conditions [72, 82]. These informations apparently support also the zoonotic implications of CFS pointed out by some authors [18, 32, 64, 65]. The data collected shows that representatives of a family of bacteria, Micrococcaceae, and of a genus, Staphilococcus, are to be seen in the blood of such cases. There is not direct proof that they cause the disease, but their presence could no longer be seen in fresh blood smears made 10-30 days after treatment and recovery. In the case of cat #66, blood culture proved Staph-positive before treatment and bacteria-negative 4 months later. All these elements are suggestive of an underlying staphilococcal infection in CFS animal patients. The use of arsenical drugs is today rediscovered against a huge variety of haematological and solid tumors. This may be the key for supporting the approval of these medicaments even against Chronic Fatigue Syndrome. In summary, this report presents evidence that a clinical CFS-like illness exists in dogs and cats. In comparison with 'healthy' and 'sick with other llness' control groups the CFS-affected animals showed a significant prevalence (60%) of Staph-positive blood cultures and presence of micrococci in the blood before therapy, with constant and stable disappearance after treatment and clinical recovery. An increased frequency of toxin-producing coagulase-negative staphilococci has been reported also in humans with chronic pain/fatigue complaints. Determining the comparative medical importance of these isolates and of the therapeutic solution produced awaits the results of future studies. Figure captions Figure 1 Cat with CFS. Micrococci-like organisms can be observed on the external surface of some red blood cells (x100). Figure 2 Staph-positive blood culture from a CFS animal patient. Figure 3 Dog with CFS and micrococci in the blood before treatment with low dosage sodium thiacetarsamide (x100). Figure 4 Gram positive cocci (staph-) in a stained smear from a colony on a Columbia plate, after rapid blood culture from a cat with CFS (x100). Figure 5 Differential diagnosis : Haemobartonella canis in a fresh blood smear from a dog (x100). Shape, colour and size (0.5-1 mm) are typicals for H. canis. Tables (coming soon) References [1] Akao Y., Yamada H., Nakagawa Y. Arsenic-induced apoptosis in malignant cells in vitro. Leuk. Lymphoma 2000; 37: 53-63. [2] Alemany M., Levin J. 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