Postweaning multisystemic wasting disease caused by circovirus in Hungary

Porcine circoviruses were first recognised in cultured cells of pig origin in 1974 but until 1991 they were not associated with a characterised diseas e (postweaning multisystemic wasting syndrome - PMWS) in Canada. The syndro me was first observed in Hungary in December 1999. Since then PMWS was diag nosed on five occasions. The authors summarize hereby the collected experie nces from the point of view of clinical, pathological and laboratory diagno sis. The clinical signs occurred at the age of 40-50 days, or at a later stage, i.e. between 70-100 days of age. Retarded growth, loss in weight-gain, incr eased consumption of food and mortality were observed (Figures 1 and 2). Th e animals became dull, pale, anaemic, and under-weighed (Figure 3). Additio nally, dyspnoe and occasionally coughing could be observed. In certain and rare cases, diarrhoea, icterus, necrotic dermatitis or abscesses in the ski n were seen. The majority of the affected pigs died within two to three wee ks, while some animals perished in days. The morbidity was 20-30 per cent w hile mortality reached 15 per cent. The pathological investigation revealed lung oedema (Figure 5), ascites, hy drothorax and hydropericardium (Figures 6 and 7). In some cases lymphadenop athy, pneumonia, mulberry heart disease, esophagogastric ulcers, E. coli-di arrhoea, hepatodystrophy and the enlargement of the spleen were observed. T he histopathological investigations showed lymphohistiocytic to granulomato us interstitial pneumonia (Figure 9), depletion of the lymphoid elements in the lymph nodes, and at the same time, infiltration by histiocytes and the presence of giant cells (Figure 10). Using polymerase chain reaction porcine circovirus type IL (PCV II) was det ected in the bone marrow and lymph nodes originating from the thoracic cavi ty (Figure 11). Cells negative for the presence but permissive for the cultivation of porci ne circoviruses were used for the isolation of PCV II. No cythopathogenic c hanges were observed even after 6-8 passages, however, the cell culture sup ernatants proved PCR positivity after 2-3 passages. It is noticable, that multiple cases of icterus in a stock were observed on ly in one occasion, and also the enlargement of the lymph nodes was rarely present. Although there are few data in the literature on PMWS associated w ith severe lung oedema, ascites, hydrothorax and hydropericardium, almost e very dissected pig showed these characteristics in this study. In accordanc e with reports from other countries the authors found the depletion of the lymphoid elements and the occurrence of giant cells in the lymphoid organs and in the lungs the most characteristics of the syndrome. However, inclusi on bodies were not observed. The decline of production of pig herds between the age of 5-13 weeks in ass ociation with anaemia, lung oedema, depletion of lymphoid elements and the occurrence of giant cells indicates the presence of PCV II and consequently the PMWS. The correct diagnosis requires special virological Investigation s, including PCR.