Table 1

Predominant syndromes and possible causes with incubation periods and geographical distributions

Predominant syndrome	Cause			Incubation period	Geographical location	Specific risk	Notes
CMV, cytomegalovirus; CSF, cerebrospinal fluid; EBV, Epstein Barr virus; EV71, enterovirus 71; HIV, human immunodeficiency virus; HSV, herpes simplex virus; JEV, Japanese encephalitis virus; LCV, lymphocytic choriomeningitis virus; MVE, Murray Valley encephalitis; SLE, St Louis encephalitis; TBE, tick borne encephalitis; TB(M), tuberculosis (meningitis); WEE, EEE, VEE, western, eastern and Venezuelan encephalitis viruses; WNV, West Nile virus.
Non-specific	Parasitic	Malaria (Plasmodium spp)	P falciparum	7 days to 1 year	Worldwide tropics	Risk highest in West Africa. Spread by female mosquitoes	History of mosquito bites is unreliable. Painless and non-irritant. Only P falciparum causes neurological illness
			P vivax	14 days–2 years	Worldwide tropics
			P ovale	14 days–2 years	Mainly Africa
			P malariae	14 days–?years	Africa
	Bacterial	Typhoid		3–56 days (average 10–20)	Worldwide	Poor sanitation	Imported cases usually from South Asia
	Viral	HIV		7–28 days	Worldwide	Sexual contact, injecting drug use	95% patients seropositive at 6 months
Encephalitis	Viral	Enteroviruses		3–8 days	Worldwide	Recent epidemics Taiwan
		Herpes viruses	HSV	Highly variable	Worldwide		Can also cause meningitis
			Varicella zoster	13–21 days	Worldwide		Usually a cerebellar encephalitis
			B virus	2–10 days		Macaque bites	Prophylactic acyclovir recommended
		Arboviruses	JEV	5–15 days	SE Asia	Seasonal peaks in transmission	Mosquito borne
			WEE	5–15 days	Western USA, South America
			EEE	5–15 days	Eastern USA
			VEE	2–6 days	South America
			SLE	5–15 days	USA
			WNV	3–12 days	America, North Africa, SE Asia, ?UK/Europe
			MVE	5–15 days	South Australia
			TBE	7–14 days	Central, Northern Europe, Asia		Tick borne
		Rabies		3 days–many years	Rare in developed countries	Animal bites/scratches	Incubation period <90 days in 85% cases
	Bacterial	Louse borne typhus		7–14 days	Worldwide	Disease of poverty and destitution; rare in tourists, aid workers possibly at risk	Human louse
		Rocky mountain spotted fever		2–14 days	USA, Canada, Mexico, South America	Can occur in urban environments	Tick borne
		Brucellosis		5–60 days	Middle East, South America, Northern Ireland	Unpasteurised dairy produce, contact with farm animals	Meningitis and encephalitis can arise as a result of brucellosis. CSF shows predominant lymphocytosis, raised protein, and normal glucose
		Secondary syphilis		6–14 weeks		Sexual contact	Prominent and distinctive rash
	Parasitic	African trypanosomiasis		T b gambiense: months/years. T b rhodesiense: weeks	Disease occurs in Africa in isolated pockets	Travel to rural areas e.g. Safari	Spread by tsetse flies. Seek expert help. If suspected may be necessary to start treatment before lumbar puncture
Meningitis	Viral	EV71, echo, coxsackie		3–8 days	Worldwide
		Polio		7–14 days	Eradicated from the Americas		Almost(!) eradicated
		Mumps		12–25 days	Worldwide	Adults	Meningitis can occur in the absence of parotitis
		EBV		35–45 days	Worldwide	Young adults
		CMV		3–8 weeks	Worldwide
		LCV		6–13 days		Animal handlers, the poor	Infection from rodent droppings
		HIV		7–28 days
	Bacterial	Meningococcus		Hours–days	Worldwide, but especially Sub-Saharan Africa, Middle East	Haj pilgrims	Outbreaks common in pilgrims returning to UK
		Pneumococcus			Worldwide	Note: penicillin resistance common in some countries (e.g. Spain, South Africa)
		Haemophilus influenzae
		Streptococcus suis			China, VietNam	Contact with pigs
		Listeriosis				Unpasteurised dairy products
		Leptospirosis		2–26 days		Watersports
		Brucellosis		As before
		Lyme disease (stage 2)		Weeks to months	North America, Europe	Hiking/camping	15% of patients affected
		Syphilis		As before
		Tuberculosis (TB)		Usually represents reactivation of latent disease		Insidious onset	Good outcome depends upon prompt diagnosis and treatment
	Fungal	Cryptococcosis		Weeks	Depends upon variety	Not clearly defined	Disease can occur in the immunocompetent in the tropics
		Blastomycosis		Not determined	USA, Canada, Africa, India, Middle East	Possibly associated with river banks	Usually evidence of skin or respiratory involvement
		Histoplasmosis		Days to weeks	Worldwide excluding Europe	Associated with bat and bird droppings	Different disease syndromes depending on region
		Coccidiomycosis		10–30 days	Semi-desert areas of the New World	Initial flu-like symptoms	Associated with erythema nodosum. CSF findings similar to TB(M)
	Parasitic—causes of eosinophilic meningitis	Schistosomiasis		Weeks to months, sometimes years	Africa, South America, SE Asia, China	Tropical fresh water contact	Extremely common in sub-Saharan Africa
		Gnathostomiasis			SE Asia, Pacific Basin	Gastronomes	Raw and pickled fish, shellfish, amphibian ingestion
		Angiostrongyliasis
		Sparganosis			Widespread in Americas and tropics		Frog and snake ingestion
		Cysticercosis (Taenia solium, pork tapeworm)			Central, South America, Asia, Africa	Swine/measley pork	All but eradicated from industrialised countries
		Strongyloidiasis			Worldwide	Poor sanitation	As part of hypereosinophilic syndrome
Fits	Bacterial	Tetanus		3–21 days	Worldwide	Tetanic spasms may mimic seizures
		TB meningitis		As for TB(M)
		Cerebral abscess		Onset usually 1–4 weeks
	Parasitic	Cysticercosis		See above	As before		Most common cause of fits worldwide
		Schistosomiasis		See above	As before
		Hydatid disease			Worldwide	Communities with close exposure to dogs	Especially Middle East
		Amoebic brain abscess		Weeks to months	Worldwide	Poor sanitation	Can be single or multiple
	Drugs	Mefloquine, chloroquine ciprofloxacin		Chloroquine, mefloquine, and ciprofloxacin are contraindicated in patients with epilepsy
Paralysis	Viral	Rabies		As above	As before	May be more common after contact with bats	“Paralytic” or “dumb” rabies
		Polio		7–14 days	See above
		Japanese encephalitis		5–15 days			Produces a syndrome similar to polio in 5% of cases
		Enteroviruses				Coxsackie, echoviruses, EV70, EV71
	Bacterial	Tetanus		3–21 days	Worldwide	History of injury in only 50%
		Botulism		12–72 hours	Rare in developed world	Usually food borne but can result from wound infection
	Post-infectious	Guillain-Barré syndrome					Associated with campylobacter, EBV, echovirus, VZV, HIV, and infection
	Ectoparasites	Tick bites		5–6 days	All continents	Hikers/campers, etc	Usually resolves rapidly with tick removal
	Algae	Paralytic shellfish poisoning, ciguateratoxin poisoning		30 mins to 6 hours	Latitudes 30°–35° N to 30°–30° S	Seafood lovers	Dinoflagellate toxins concentrated through food chain