STREPTOCOCCOSIS

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Causative Agent(s)

Streptococcus suis

It is an encapsulated gram-positive coccoid bacterium.

Clinical Presentation and Epidemiology

Streptococcus suis is an emerging zoonotic agent occurring worldwide.

Several streptococcal species can be found in the tonsils, intestines, and genital tracts of clinically healthy pigs.

The following Streptococcal organisms are considered part of the intestinal microflora in swine: Streptococcus hyointestinalis, Streptococcus suis, Streptococcus alactolyticus (Streptococcus intestinalis), and Streptococcus bovis, Streptococcus suis, Streptococcus porcinus, and Streptococcus dysgalactiae subsp. equisimilis, Streptococcus orisuis and streptococcal mutans- like strains are normal flora in the mouth of pigs. In the vagina Streptococcus hyovaginalis and Streptococcus thoraltensis are also seen.

The clinical signs observed are:

In per acute cases, pigs are usually found dead with no premonitory signs.

In acute cases, the following clinical signs observed are fever, congested mucous membranes, anorexia, depression, dyspnoea, cyanosis, and shifting lameness, nervous signs due to

meningitis which include opisthotonos, nystagmus, incoordination, inability to stand, paddling and convulsions, are also manifested. Other signs noticed are arthritis, rhinitis, vegetative valvular endocarditis, abortion, vaginitis, and loss of condition.

Diagnostic Considerations

The samples taken for bacterial isolation are swabs of tonsils and genital tract and feces of infected animals.

Presumptive diagnosis of this disease is based on clinical signs, age of animals, and macroscopic lesions.

Isolation of the causative agent usually confirms the diagnosis.

Collection of more than one alpha-haemolytic colony from different tissues of the same animal or from different animals in the same herd is usually recommended because more than one serotype or strain of S. suis could cause a single outbreak.

After isolation, biochemical tests of S. suis isolates can be done with the use of only two tests, which are amylase positive and negative.

Serological tests are available for the detection of antibodies against S. suis but are generally not useful.

Polymerase chain reaction (PCR) has also been used to detect some serotypes, but it is not used routinely in veterinary practice because of cost.

Management and Treatment

Penicillin, 20,000 IU/kg b.w., q24h 5 days I.M.

Ampicillin, 10-50 mg/ml concentration, 7mg/kg b.w., q24h 5 days I.M.

 

Other approaches to reduce spread include:

Early detection of nervous signs.

Treatment with an anti-inflammatory agent.

In outbreaks all pigs should be treated even if only one is affected or found dead.