Blackleg in cattle in the state Mato Grosso do Sul, Brazil: 59 cases

Abstract

This study aimed to review cases of blackleg (Clostridium chauvoei infection) diagnosed in cattle from Midwestern Brazil from 1994 to 2014 considering epidemiological, clinical, necropsy and histopathological findings. Also the following laboratory tests were used for the diagnosis of some cases of blackleg: microbiological culture and identification of the agent, microbiological culture and identification of the agent by the polymerase chain reaction (PCR), and identification of the agent in formalin fixed paraffin embedded tissues (FFPE). Criteria for presumptive diagnosis of blackleg included necrohemorrhagic emphysematous myositis consisting of inflammatory infiltrate, coagulative necrosis of myofiber, interstitial edema, hemorrhage, and gas bubbles between myofibers. Fifty nine cases from 51 outbreaks of blackleg were found, which corresponded to 1.1% of 5,375 cattle deaths investigated. In five of those outbreaks, samples of affected muscles cultures for the identification of pathogenic clostridia were made. Another three samples of similar material were cultured for clostridia with subsequent identification of the isolate by PCR. Twelve samples of FFPE affected muscle fragments were submitted to PCR for identification of the etiological agent. Except for January, cases were observed in each month of the year, with higher numbers in July-October. Most affected cattle were in the age of 7-12 years, but calves younger than 6 month-old and older than 24 months were also observed. Vaccination histories were scarce. In 32 outbreaks some vaccination history was available, but only in two of those vaccination has been carried out properly. In 56 six cases the skeletal muscles were involved. Muscles of the hind limbs were the most affected. In ten cases muscles of the tongue, myocardium and diaphragm were also affected. In three of the cases the visceral form was observed. Deaths occurred after a clinical course of 6-24 hours, but in most cases cattle were found death. Sudden death was the outcome in visceral cases (cardiac) blackleg. Clostridium chauvoei was confirmed to be the cause by culturing in 5 cases, and by PCR and histopatology in 8 cases. Bacterial culture followed by PCR did not demonstrate C. chauvoei. Calculation of the economic impact indicates that blackleg is a frequent disease in the state of Mato Grosso do Sul (MS) that inflicts significant economic loss. The amount of these losses would be reduced through proper vaccination programs against the prevalent strains of C. chauvoei in the region.

Clostridial diseases diagnosed in cattle from the South of Rio Grande do Sul, Brazil. A forty-year survey (1978-2018) and a brief review of the literature

“…Gray matter hemorrhages, decubitus pneumonia and asphyxia lesions reported by some authors (Valette & Petermann 1988) Roughly our data are similar. Surveys of the prevalence of clostridial diseases in Brazil generally indicate blackleg as the most frequent disease (Correa et al 1980, Riet-Correa 2007a, Heckler et al 2018. In our study, this is also a trend.…”

“…Of the 34 outbreaks or sporadic cases of blackleg diagnosed in cattle, 15 occurred in the winter, nine in the spring, seven in the fall, and three in the summer. As has already been observed (Heckler et al 2018) blackleg cases tend to be distributed throughout the year without showing specific seasonality (Table 1). However, it is also described that the prevalence of the disease was higher during the fall (Riet -Correa 2007a).…”

“…Usually 6-24 month-old well nourish cattle are affected (Useh et al 2006), but cases were already reported in a 3-day calf (Sojka et al 1992) and a bovine fetus transplacentally infected (Abreu et al 2017). In Mato Grosso do Sul state the disease has been diagnosed in cattle of 2.5-3 years old, not vaccinated or vaccinated long time before the outbreak (Riet- Correa 2007a, Heckler et al 2018.…”

“…In the periphery, the muscle is red and moist due to edema (early lesions). At the center of the lesion, the affected muscle is dark-red, dry and friable (mature lesions) (Barros 2016b, Heckler et al 2018. Muscle affected by blackleg often has a butyric odor, such as rancid butter (Cooper & Valentine 2016).…”

Bovine rabies: economic loss and its mitigation through antirabies vaccination

“…The methodology used to estimate the economic losses due to bovine rabies-related deaths used in this study is similar to those used in other studies to estimate the economic losses caused by a specific disease in cattle (Heckler et al 2018) Another methodology used to estimate economic losses caused by a particular disease is the database from veterinary diagnostic laboratories -VDLs (Lima et al 2005). In this approach, the percentage of d cases of a particular disease in cattle diagnosed in a given VDL is calculated over the total number of diagnosis performed in cattle in that VDL and this percentage is extrapolated as the percentage of deaths caused by this disease in the region of the VDL.…”