1142 BRIEF REPORTS

junctivitis. There has been an epidemiologic relation- ship between outbreaks of dysentery and Reiter’s syndrome, and this syndrome has been reported to fol- low shigella infection (6,7). Less commonly, Reiter’s syndrome may follow infection with Yersinia enterocoli- tica (8,9). Berglof (3) described one case of urethritis, conjunctivitis, and arthritis associated with salmonella infection. Jones (10) described a 12-year-old girl who developed Reiter’s syndrome after a Salmonella typh- imurium infection. The joint fluid in that case, as in ours, was cloudy and contained neutrophils, but was sterile. Their patient’s symptoms also resolved coinci- dent with antibiotic therapy.

There is an association between Reiter’s syn- drome and the histocompatibility antigen HLA-B27 (1 1). Aho (9) found the HLA-B27 antigen in approxi- mately 90% of the patients who developed reactive ar- thritis following enteric infection. HLA antigen data are not available for the previously reported cases of com- plete Reiter’s syndrome and salmonella infection. Both brothers in this report were found to carry the HLA- B27 antigen. These cases reaffirm the association be- tween salmonellosis and Reiter’s syndrome and add weight to the suggestion of a genetic basis for Reiter’s syndrome.

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

REFERENCES David JR, Black RL: Salmonella arthritis. Medicine (Bal- timore) 39:385403, 1960 Ortiz-Neu C, Marr JS, Cherubin CE, Neu HC: Bone and joint infections due to Salmonella. J Infect Dis 138:820- 828, 1978 Berglof FE: Arthritis and intestinal infection. Acta Rheum Scand 9:141-149,1963 Vartianen J, Hurri L: Arthritis due to Salmonella typhimu- rium. Acta Med Scand 175:771-776, 1964 Warren CPW: Arthritis associated with salmonella infec- tions. Ann Rheum Dis 29:483-487, 1970 Young RH, McEwen EG: Bacillary dysentery as the cause of Reiter’s syndrome. JAMA 134: 1456-1459, 1947 Paronen I: Reiter’s disease: a study of 344 cases observed in Finland. Acta Med Scand 212 (Suppl):l-l12, 1948 Ahronen P, Sievers K, Aho K: Arthritis associated with Yersinia enterocolitica infection. Acta Rheum Scand

Aho K. Ahvonen P, Alkio P, et a1 HL-A27 in reactive ar- thritis following infection. Ann Rheum Dis 34

Jones RAK: Reiter’s disease after Salmonella typhimurium enteritis. Br Med J 1:1391, 1977 Brewerton DA, James DCO: The histocompatibility anti- gen (HL-A 27) and disease. Semin Arth Rheum IV191- 207, 1975

15~232-253, 1969

(Suppl):29-3 1, 1975

INTRAARTICULAR MICROFILARIAE IN LABORATORY ANIMALS ABRAHAM WEINBERGER, H. RALPH SCHUMACHER, and DAVID J. WEINER

Diroflaria immitis and Dipetalonema species are common parasites of canines and New World monkeys. Dogs and monkeys are widely used for various experi- ments including those on joints. During experimental studies with these animals, microfilariae have been found in the synovial fluid of a dog and in a synovial membrane vessel lumen of a monkey knee joint. These organisms are a possible source of pathologic changes that could be confused with those produced by experi- mental manipulations.

David J. Weiner, PhD. Abraham Weinberger, MD, H. Ralph Schumacher, MD;

Materials, Methods, and Results. Fifteen “semi- conditioned” dogs brought from the south of the United States were used in a study of the effect of trauma on the canine joint. All dogs had been housed in the Phila- delphia area for 7-10 days before the experiments were performed and appeared clinically well. The normal sy- novial vascular ultrastructure was studied in 10 young Cebus albifrons monkeys obtained through a supplier from Colombia, South America. All the animals enter- ing the study had grossly normal appearing joints.

Synovial fluid (0.25 ml) obtained from the con- trol joint of one dog showed a microfilaria (Figure 1).

Address reprint request to H. Ralph Schumacher, MD. Vet-

Submitted for publication April 27, 1979; accepted May 24,

The cell count of this synovial fluid Was 450/mm’. All cells were SynOVial lining Cells (nucleated cell count in our control joint fluids varies from none to 700/mm’).

erans Administration Hospital, Philadelphia, PA 19 104.

1979.

1143

placed on glass slides and examined by light micros- copy. Another 1 ml of blood in heparin was added to 10 ml of a lysing solution (Triton X-100, NaCO,, and H,O) which was then thoroughly mixed. The lysed blood was placed in a syringe and pushed through an 8p pore size Millipore filter (1). The filter was stained (methylene blue) and examined by light microscopy at a magnilica- tion of 100. Both the Knott’s test and Millipore filtra- tion showed many microfilariae. Serum containing mi- crofilariae was used in the acid phosphatase test for identification of the microfilariae (2) and revealed a typ- ical staining pattern for D immitis with 2 distinct acid phosphatase positive sites on the body of the organism (Figure 2). Six other Bogs used in our studies were killed and postmortem examination of the heart for detection of adult filaria was performed. In all 6 many adult worms of D immitis were observed.

Light microscopic studies of the synovial tissue from the knee of the dog in which the microfilaria was found revealed synovial lining cells of one to three lay- ers with moderate vascular congestion. Neutrophils or other inilammatory cell infiltrations were not found. Electron microscopic studies of the synovial membrane showed no abnormalities. Electron microscopy of a specimen of synovial membrane from the monkey re-

Figure 1. A microfilaria in the joint fluid of a dog (X 200). vealed a small vessel in which a cross section of a micro- Maria, probably of Dipetalouema species, the most com-

For detection of systemic microfilariae the Knott test mon microfilariae in monkeys, was identified (Figure 3). was used (1). One milliliter of blood was placed in a No other abnormalities could be detected. tube with 9 ml of 2% formalin and thoroughly mixed. Discussion. Usually blood microfilariae are The tube was centrifuged for 5 minutes at 1,500 rpm, found within vessels or in organs rich with blood such the supernate was discarded, and the sediment was re- as spleen, heart, or lung (3). The synovium is certainly suspended with several drops of 0.1% methylene blue another quite vascular tissue. The anatomic localization

Figure 2. Diro#lariue immitis from the blood of a dog. Note the 2 distinct spots @ink) on the body of the orga- nism (acid phosphatase s t a h , X 100).

1144 BRIEF REPORTS

Figure 3. Cross section of 2 microfilariae (arrows) in the lumen of a synovial vessel of a monkey. RBC = erythrocyte; E = vascular endothe- lium (electron micrograph X 40,000).

of the adult D immitis in the animal host is the pulmo- nary artery and right ventricle. The infection is trans- missible by mosquitos and the parasite is commonly found in canines in the southern part of the United States. The monkey microfilariae, as seen in the small synovial membrane blood vessel, are present in the bloodstream, with the adults inhabiting the peritoneal cavity.

Although filariae may cause arthritis in humans (4), joint manifestations of this parasitic infection in an- imals have not been described, thus clinical manifesta- tions may not occur or may be very rare. Indeed, our animals in which microfilariae were found in the joint did not show any clinical joint symptoms or signs.

The diagnosis of D immitis can be made by find- ing microfilariae of appropriate morphology in the

BRIEF REPORTS 1145

blood. The microfilariae are extremely small ( 2 9 7 ~ X 6.9~) and are seldom found in sections from tissue biopsies. In animals there is no pathologic response to live D immitis microfilariae, but a mild tissue reaction can occur around minute degenerating worms ($6). We could not find any filarial worms in the synovial tissue of the dog in which microfilaria was observed in the sy- novial fluid. The congestion of vessels seen in the dog described might be attributed to the presence of the parasite within the joint since it was greater than seen in most other control joints. Since such parasitic infesta- tion can occur in animals even without clinical manifes- tations, investigators using laboratory animals for vari- ous studies should be aware of the possibility of the parasites affecting the joints. Careful synovial fluid analysis and synovial membrane biopsy studies should be done when a study on animal joints is designed. In- deed, synovial membrane histologic studies in our mon- keys previously showed thorns embedded in synovium (7) that were not evident by any clinical features but were inducing a mild granulomatous reaction.

REFERENCES

I . Altman NH: Laboratory diagnosis of Dirofilaria immitis- evaluation of current tests in canine heartworm disease- the current knowledge. Edited by RE Brandley. Gaines- ville, Florida IFAS-University of Florida Publication,

2. Chalifoux L, Hunt RD: Histochemical differentiation of Diroflaria immitis and Dipetalonema reconditum. J Am Vet Med Assoc 158:601-605, 1971

3. Soulsby EJL: Textbook of Veterinary Clinical Para- sitology. Vol. 1. Philadelphia, F.A. Davis Company, 1965, pp 100-113

4. Dourg P, Pattin S, Dienat B, Rour R, Delahage R P Les rheumatisme parasitaires. Sem H6p Paris 53: 1359-1363, 1977

5 . Nelson GS: The pathology of filarial infectious. Helm Abstr 35:311-366, 1966

6. Dhayagude KG, Amin BM: Microfilarial granulomata of the spleen. Am J Pathol 18:351-361, 1942

7. Schumacher HR, Majno G: Thorns in the skin and joints of the monkey. Arch Pathol84536-538, 1967

1972, pp 87-93