zoonoses and communicable diseases common to ... - PAHO/WHO

ENTEROCOLITIC YERSINIOSIS 129mates that outside Great Britain there have been 27 cases of septicemia caused byblood transfusion, 17 of them fatal. One case of autologous transfusion has also beendescribed (Richards et al., 1992).The mode of transmission is not well known either, but it is widely accepted thatthe infection is contracted by ingestion of contaminated foods, as in the case of otherenterobacterial diseases, as well as by contact with carrier animals and by humanto-humantransmission. It is known that Y. enterocolitica can multiply at refrigerationtemperature. It is believed that this led to the 1982 epidemic in the US (see thesection on occurrence in man) produced by recontaminated pasteurized milk. Thisepidemic also reveals that serotypes other than 3, 5, 8, and 9 can give rise to the disease,although less commonly.Role of Animals in the Epidemiology of the Disease: Although not providingdefinitive proof, the accumulated data in countries with a high incidence of thehuman disease indicate that swine are probably an important reservoir of Y. enterocolitica,particularly serotype O:3, which is currently the prevalent type, and typeO:9, which is also frequent in swine. The disease caused by a dish prepared with pigintestines (“chitterlings”) in various American cities is good evidence that the infectionis transmitted through food.Diagnosis: In cases of enteritis, appendicitis, erythema nodosum, and reactivearthritis, the possibility of Y. enterocolitica infection should be considered. Theagent can be isolated from the patients’ feces. MacConkey agar and a selective agarcalled cefsulodina irgasan novobiocin (CIN), created specifically for Yersinia, canbe used for this purpose. Both biotype and serotype should be identified. The coldenrichment technique is useful, particularly in the case of carriers that may excretefew Y. enterocolitica cells. Samples are suspended in peptone culture broth or abuffered phosphate solution for 3 to 7 days at 4°C to encourage the growth of Y.enterocolitica and suppress that of other bacteria. However, routine diagnosis is animpractical procedure, takes a long time (about 1 month), and does not exclude nonpathogenicYersinia.Tube serum agglutination and the ELISA test can be used with good results asadditional diagnostic techniques. Active infections produce high titers that declineover time. Serum agglutination titers of 1/40 to 1/80 are rare in healthy individuals,but common in yersiniosis patients and can rise to very high titers. Positive cultureswithout clear evidence of gastroenteritis are not always accompanied by a highserum agglutination titer.Very high titers are common in patients with acute appendicitis (Schiemann, 1989).In countries where serotype 9 is a frequent pathogen for man and is also harbored byswine, cross-reaction between Brucella and that serotype may cause difficulties.Antibodies in swine against serotype 9 of Y. enterocolitica can be differentiatedfrom those against Brucella by flagellar antigens, which Y. enterocolitica has andbrucellae do not. Y. enterocolitica also possesses the common enterobacterial antigen,which Brucella does not have and which therefore may also be used to distinguishthem (Mittal et al., 1984). Other animals that have been exposed to serotype9 can also show cross-reactions with Brucella.A comparison of three tests for serum diagnosis of type O:3 (immunoelectrophoresis,ELISA, and agglutination) produced similar results in terms of sensitivityand specificity (Paerregaard et al., 1991).