Meningitis

Investigation into a meningitis problem

Causal agent

The classical cause of meningitis in piglets, weaners and growers is Streptococcus suis II.  However, several other bacteria can cause meningitis namely Haemophilus parasuis and septicaemic Escherichia coli or Bowel Oedema (E. coli F18)

Age group

Any.   Meningitis classically occurs between 3-60 kg.

Haem. parasuis in naive finishing and adult pigs can cause a devastating acute fatal meningitis

Clinical signs

Acute

The pig becomes incoordinated often with uncontrolled eye movements

Rectal temperature is increased to 40-41°C

As the condition progresses the pig will fall over and thrash with all four legs on the floor.

The pig may traumatise itself during these thrashing movements

Death can occur quickly especially if the pig is stressed.  In the farrowing house the condition can then be misdiagnosed as an overlaid pig

If treatment is late a neurologically damaged pig may result

Normal pig

No clinical signs, the organism lives on the tonsils and upper respiratory tract of the normal healthy pig

Meningitis streptococcus suis

Meningitis Strep

Two growing pigs with meningitis

Infectivity

Most pigs are infected

Transmission

From the mother at birth by nose to nose contact

Between pigs by nose to nose contact

Post-mortem Lesions

None particularly obvious.  Meningeal congestion and tags are suspicious but most veterinarians examine so few brains it would be difficult for them to differentiate between the normal range of meningeal changes.  The picture shows the brain in a sectioned head

                                    

Diagnosis

Culture of Streptococcus suis II from cerebrospinal fluid (CSF)

Using a 18 gauge 1.5 inch needle.  Place the pig in a dorsal position.  Flex the head over the edge of the post-mortem table.  Feel for the atlas occipital junction.  Swab the skin with surgical spirit.  Insert the needle and ‘walk’ the needle down the brain case off the occipital joint.  Attach a sterile 2 ml syringe.  1 ml of clear CSF should be readily easy to extract

The reason for using CSF is that Strep. suis is widespread on the skin and upper respiratory tract and post-mortem knives are easily contaminated leading to a misdiagnosis

Histological examination of the meninges including a Gram stain

Treatment and Control

Investigation of meningitis outbreak.  Checklist for investigation

Individual

The pig is dying

Treatment must be rapid and vigorous

Ceftiofur by intramuscular injection is the medicine of choice, at 3mg/kg

Penicillin may be used at a high dose if ceftiofur is not available

Treat with ceftiofur every 12 hours until clinical signs subside

When procaine penicillin is used, a few pigs can develop a procaine allergy and go into anaphylactic shock

If weaned isolate the pig.  If not weaned place in creep area

Keep in a darken room

Provision for pain relief should be considered: Meloxicam 0.4 mg/kg

If fits are extreme give a sedative as necessary

Provide water by mouth from a syringe is necessary.  Note a pig drinks 1 litre per 10 kg per day so a few syringe fulls is not sufficient

Control

Most pigs carry Strep. suis on their tonsils and upper respiratory tracts.  The causal factor that results in the clinical signs is that the pig is subjected to too much stress or other disease

Draughts particularly in farrowing houses and nurseries

Wet and cold environments, common if weaners placed into cleaned houses.  In outdoor situations use of damp mouldy straw often precipitates a meningitis ‘outbreak’.

Excessive change in temperature in the pigs sleeping area

Pigs being moved and mixed resulting in disturbed social hierarchy

Gas levels being too high.  Carbon monoxide posioning from gas heaters

Check colostrum management, especially cases in the farrowing house.

 Feed-back programmes also should be reviewed.

Medication with amoxycillin in the water supply and tetracycline in-feed (800ppm) may be useful

Common differentials

Haemophilus parasuis, septicaemic E.coli and Bowel Oedema. Intoxication with brewer products.  Water deprivation.  Porcine Stress Syndrome.  Trauma to the head. Aujeszky’s Disease.

Zoonotic Implications

Strep. suis can rarely cause a fatal meningitis in man  It may also cause endocarditis and arthritis in man.  It is an occupational hazard.  Ensure staff handling pigs and pig meat wash their hands regularly and cover all skin injuries.