Portal de Periódicos da CAPES

Epidemiology, clinical signs, laboratorial and pathological findings in eight outbreaks of botulism in cattle in Rio Grande do Norte state, Northeastern Brazil.

2014; UNIVERSIDADE FEDERAL DO RIO GRANDE DO SUL; Volume: 42; Linguagem: Inglês

1679-9216

Antônio Carlos Lopes Câmara, Camila Marinho de Miranda Oliveira, André Menezes do Vale, JULIANA SPIRLANDELI BATISTA, Benito Soto‐Blanco,

Neurological diseases and metabolism

Background: Botulism is caused by a neurotoxin produced by Clostridium botulinum, a gram-positive bacterium, sporeforming anaerobe. In Brazil, this disease has relevant importance causing economic disturbance in livestock production. The present study aimed to report the epidemiology, clinical-pathological and laboratorial fi ndings of eight outbreaks of botulism in cattle from Rio Grande do Norte, Northeastern Brazil. Material, Methods & Results: Clinical and epidemiological data of eight outbreaks of botulism were obtained during visits to farms from Mossoro, Serra do Mel, Governador Dix-Sept Rosado and Olho D’agua dos Borges municipalities, located at the semiarid region of Rio Grande do Norte state, Northeastern Brazil. The outbreaks occurred in July 2009, August and September 2010, and April, May and October 2013. Blood and cerebrospinal fl uid samples were collected from eleven and six animals, respectively, for laboratorial analysis. Ten cattle that recently died were necropsied, and fragments of several tissues (central nervous system, liver, kidney, heart and small intestine) were collected for histopathological examination. The observed clinical signs varied according to the clinical evolution of the disease, and included progressive paralysis of hindlimbs and sternal decubitus. The common clinical fi ndings in all cattle was decreased muscular tonus of tongue and tail, diffi culty swallowing and perianal hypoalgesia. However, one outbreak was characterized by the onset of symptoms in forelimb motor incoordination. All animals showed varying degrees of dehydration. The clinical course varied from hyperacute (within 24 h) to subacute (within 7 days). All affected cattle died, totalizing 70 deaths. The morbidity and mortality of the disease was 12.3%, and the lethality reached 100%. Hematology revealed the occurrence of leukocytosis with neutrophilia and hemoconcentration in three and two animals, respectively. Six animals showed hyperproteinemia. The cerebrospinal fl uid analysis showed density in the upper limit (1.010) or increased density (1.015 and 1.020) in fi ve of six cases (83.3%), while the leucocytes remained within the physiological limits, reaching the maximum of four leukocytes/μL. Gross pathological fi ndings consisted of pulmonary hypostasis and petechial and ecchymotic hemorrhages in the pericardium, and associated to the long period of recumbency or death agony, respectively. The analyzed tissue fragments showed no signifi cant microscopic change. Discussion: The outbreaks of botulism in cattle from Rio Grande do Norte state were linked to the lack or inadequate mineral supplementation and the absence or improper immunization against botulinic toxin. The nutritional defi ciency of phosphorus is well known in the farms of the region and the carcasses of dead animals are usually not removed from the grasslands, which are factors that favor the osteophagia by cattle. Another relevant aspect is still the existence of farmers releasing their cattle into areas of dumps or allowing the access to inappropriate foods. Although forbidden by law, the use of poultry litter for animal feeding was the probable cause of the one outbreak, since no other risk factor was identifi ed at the property. Thus, the fi ndings of this study show the need for the establishment of an effi cient control and prophylaxis program against the botulism.