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
				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.