Journal of the Neurological Sciences, 1977, 34 37-42 © Elsevier Scientific Pubhshmg Company, Amsterdam - Printed m The Netherlands
37
N E U R O M U S C U L A R P A R A L Y S I S C A U S E D BY T I C K E N V E N O M A T I O N
JOHN PEARN Department of Chtld Health, Royal Chtldren's Hospttal, Brtsbane (Austraha) (Received 28 March, 1977)
SUMMARY The Austrahan scrub-tick Ixodes holocyclus causes a series of slgmficant toxic effects m its victims The most ~mportant feature of tick envenomatlon is neuromuscular paralysis Chddren poisoned by ticks may mamfest only local motoneural effects, usually facml paralysis Progressive ascending flaccid paralysis occurs if the removal of an embedded tick is delayed The specific neurological features of tick-bite are discussed m the hght of a series of 6 children who all showed signs of t~ck paralysis Tick venom is known to slow nerve conduction, and may have a botullnum-hke effect at the neuromuscular.lunctlon The hterature on the neurological effects of tlck-envenomatlon is rewewed
INTRODUCTION Envenomatlon by the Austrahan scrub-tick, Ixodes holocyclus, causes profound neuromuscular paralysis The venom as extremely potent Envenomatlon of humans following tick-bite is well recognized from Austraha (Ferguson 1924, Hamilton 1940, Pearn 1966), from North America (Costa 1952, Hailer and Fabara 1972, DeBusk and O ' C o n n o r 1972), from Europe (Force and Esvan 1968, Lechevaher, Houttevllle and Blet 1974), and from Africa (Editorial Brtt med J 1969) Children particularly are affected, and child deaths from bulbar and respiratory paralysis, although now rare, are always a threat if the embedded tick is not disdiscovered, or if the possibility of tick envenomatlon is not considered in the differential diagnosis of an acutely weak chdd There is a particular risk if a chdd returns from overseas to an area where ticks are unknown Tick bite may result in local or generalized allergic reactions (Trlnca 1964,
Address for reprints Department of Chdd Health, Royal Chddren's Hospital, Herston, Brisbane, Australia 4029
Present
Present
Virtual complete paralysis one day Complete areflexla D T R after removal of the tick Severe reappeared four days paralytic squint No bulba~ after removal of t~ck involvement cllmcally Complete areflexia D T R reappeared on Day 11 after tick removal
Normal
Ascending flaccid paralys~s By Day 4 unable to sit or stand Respiration purely dlaphragmatic Bdateral pupdlary ddatation
No signs of generalized weakness
Case 3 3-year-old girl
Case 4 6-year-old girl
Marked
Case 6 3-year-old girl
Complete areflexla
Absent
Case 5 Moderate weakness of lower hmbs Normal 3-year-old boy but able to stand and walk at all t~mes Some dysarthna
Progressive ascending flaccid paralysis Bulbar paralysis on Day 3 after tick removal, with respiratory difficulty
Present
Gross bilateral facial palsy
Present
Facial weakness
Marked
Absent
L sided ptosls L Bell's palsy
Present
Case 2 2-year-old girl
Ankle D T R absent Knee D T R hyporeflexic Upper limb D T R hyporeflexlc
Total paralysis of lower limbs Generahzed hypotonm Unable to hft arms Hand grip weak Poor head control
PtosJs
Case 1 3-year-old girl
Deep tendon reflexes
Peripheral muscle paralysis
Case
10 rag/100 ml, sugar 70 mg/ 100 ml No response to i v edlophomum, l v antlvenene given with reversal of neurological signs commencing within 1 hi Complete recovery
C S F No cells/ram ~ Protein
25 mg/100 ml, sugar 80 mg, 100 ml
C $ F No cells/mm ~ Protem
Tick embedded behind left ear, child presented because ot "unusual facial appeaiance
Presented with stridoi Complete recovery 2 ~eeks after removal of tick
Still weak 7 days after removal of the tick
No ophthalmoplegm Complete recovery 7 days after removal of tick
Notes
CLINICAL DETAILS OF N E U R O L O G I C A L SIGNS D U E TO E N V E N O M A T I O N BY THE A U S T R A L I A N SCRUB-TICK
TABLE 1
39 B a n f i e l d 1966, S u t h e r s t a n d M o o r h o u s e 1971), in t h e z o o n o t l c t r a n s m i s s i o n o f t y p h u s ( A n d r e w , B o n n i n a n d W i l l i a m s 1946), m y o c a r d l t i S ( P e a r n 1966) a n d local i n f e c t i o n a n d i n d u r a t i o n at the bite site ( T o m k l n s 1963) It is t h e p u r p o s e o f this r e p o r t t o r e v i e w t h e specific n e u r o m u s c u l a r c o m p l i c a t i o n s o f tick e n v e n o m a t l o n CASE REPORTS Six new cases of paralysis caused by the Austrahan scrub-tick were encountered between 1971-1975 mcluswe All occurred m chddren under the age of seven years Cllmcal detads of paralytic features are shown m Table 1 One child presented with a left Bell's palsy with the tick embedded behind the left ear Four children had marked generalized signs of progressive ascending flaccid paralysis which recovered spontaneously - - all children were nursed beside respirators and a policy of watchful antJopatzon employed One chdd (Case 6 - - see Fig 1) became severely paralysed with bulbar involvement, and was given canine anti-tick antlvenene (Commonwealth Serum Laboratories 1974) w~th satisfactory results - - th~s latter case also recovered completely without sequelae
/
Fig 1 Three-year-old gzrl (14 3 kg) with severe neuromuscular paralysis, 3 days after removal of a scrub-tick (Ixodes holocyclus) from the occipital region of the scalp Ptosls and foot-drop are evident Bulbar paralysis developed several hours later
40 DISCUSSION The scrub-tick Ixodes holo&~ lus (Fig 2) Js common throughout coastal Austraha, m heavily infested areas numerous domestic pets die each year from the paralytIc effects of its toxin The hfe-cycle consists of four stages - - egg, larva, nymph and adult - - but the bate of the gravld females only ~s sagmficant from the point of view of neuromuscular paralysas (Moorhouse 1967, Berry 1974) The hypostome penetrates the skin and the tack progressively burrows into the epidermis causing the so-called "feeding lesion" (Moorhouse and Tatchell 1969, Tatchell and Moorhouse 1970) It is from this s~te that the toxin-loaded salivary fluId (Kaare 1966) &ffuses to produce its local and systemic effects The North American wood tick, Dermacentot andetaom, and the common dog tick, Dermacentor vartabths, also cause human paralysas (Costa 1952, DeBusk and O'Connor 1972), improvement m muscle power after removal of these latter tacks seems to be much qmcker than that observed m cases envenomated by the Australian Ixodes holoo'clus (Costa 1952, Murnaghan 1960) Nevertheless, mortality from paralysis m a Cana&an seraes was 12 Yo (Rose 1954) A feature of the paralysis produced m children by Ixodea holocvclus is that ~t continues to progress even after removal of the embedded tick (see Case 6, and Pearn 1966) The venom may act locally on nerves by diffusion from a contiguous sate of attachment, usually the facml nerve is involved m this phenomenon as the ticks often
Fig 2 The Austrahan scrub-tick, lxodes holocyclus Fully engorged female, removed from a dog showing early s~gns of neuromuscular paralyszs
41 e m b e d m o r b e h i n d the ear ( F o s t e r 1931, Crossle 1932, A r t h u r 1965, P e a r n 1966) C o n s i d e r a b l e interest s u r r o u n d s the possible m o d e o f a c t i o n o f the v e n o m M u r n a g h a n (1960) suggested t h a t there were 2 possible sites o f a c t i o n - - one on nerve c o n d u c t i o n itself with greatly reduced nerve action potentmls, a n d a second b o t u h n u m hke effect preventing the release o f acetylchohne Synthesis a n d storage o f acetylc h o h n e at the small t e r m i n a l m o t o r fibres seemed to be unaffected, at least for D e r m a ¢ e n t o r a n d e r s o m v e n o m C h e r m g t o n a n d S n y d e r (1968) a n d H a i l e r a n d F a b a r a (1972) also f o u n d r e d u c e d nerve c o n d u c t i o n velocmes m a 5-year-old girl p a r a l y s e d by an umdentlfied tick C h e r m g t o n a n d S n y d e r (1968) felt that no defect was present at the n e u r o m u s c u l a r j u n c t i o n O t h e r w o r k e r s (Lagos a n d Thles 1969, Esplln, Phllhp a n d Hughes 1960) have suggested that the v e n o m has a b~phaslc a c t i o n - - l n m a l l y on the g a m m a system affecting muscle spindles, a n d later affecting nerve c o n d u c t i o n Suggestions t h a t tick v e n o m m a y mvolve the g a m m a efferents are s u p p o r t e d by the recent findings that l e v o d o p a - c o m p e n s a t e d P a r k m s o m a n patients can suffer acute P a r k m s o m a n crises after tlck e n v e n o m a t l o n (Sax a n d M a j l s z e n k l e r 1971, C u l e b r a s 1971) There is one r e p o r t suggesting that tick venom m a y have a d~rect effect on muscle (Boffey 1973) It is lnterestmg m this regard to note that the n e u r o t o x m notexln f r o m the A u s t r a l i a n T~ger snake also has a b o t u h n u m - h k e effect as well as a d~rect m y o t o x l c a c t i o n ( H a m s , K a r l s s o n a n d Thesleff 1973, Harris, J o h n s o n a n d K a r l s s o n 1975) L~ke the different p a t h o p h y s l o l o g l c a l actions o f different snake venoms it is hkely that different species o f t~ck vary m the way m which their v e n o m causes the vamous neurological signs o f e n v e n o m a t l o n The neuroparalyt~c effects o f the v e n o m are n o t species-specific Dogs, cats a n d even p a r r o t s ( D o m r o w a n d D e r r i c k 1965) are affected This non-selectwe a c t i o n offers c o n s i d e r a b l e scope for further l a b o r a t o r y investigation o f ~ts neurotoxlc effects ACKNOWLEDGEMENTS
The author thanks Drs G Bourke, N Chalk, R O'Redly and R Tlernan for gracious permission to review details of cases under their care, the author also thanks the Supermtendent, Mater Mlserlcordme Children's Hospital, Brisbane, for permission to pubhsh chmcal photographs
REFERENCES Andrew, R , Bonmn, J M and S Wflhams (1946) Tick typhus m North Queensland, M e d J .,lust, 2 253-258 Arthur, D R (1965) Ticks m Egypt m 1500 B C ? Nature (Lond), 206 1060-1061 Banfield, J F (1966) Tick bites m Man, M e d J A u s t , 2 600-601 Berry, F B (1974) More deadly than the male, M e d TmTes, 102 23-27 Boffey, G C (1973) Creatme phosphokmase elevation m a case oft~ck paralysis, Canad meal Ass J , 108 866-868 Chermgton, M and R D Snyder (1968) Tick paralysis - - Neurophyslologlc studies, New Engl J M e d , 278 95-97 Commonwealth Serum Laboratories (1974) Tick Antlvenene In CSL Medtcal Handbook, CSL Pubhcat~ons, Parkvllle, V~ctona, Austraha, pp 204-206 Costa, J A (1952) T~ck paralysis on the Atlantic seaboard, Amer J Dts ChtM, 83 336--347
42 Crossle, F C (1932) Facial paralysis following tick bite, M e d J Aunt, 2 764 Culebras, A (1971) More on tick bite m Parkmson's &sease, Nea Engl J M e d , 285 754 DeBusk, F L and S O'Connor (1972) Tack toxacosls, Pedtatru ~, 50 328-329 Domrow, R and E H Derrick (1965) l~odev holo~vchls, the man-biting tick m S E Queensland Aust J Sct, 27 234-235 E&torlal (1969) Tick paralysas, Bttt med J , 3 314-315 Esphn, D W , C B Phllhp and L E Hughes (1960) Impaarment of muscle stretch reflexes m tfck paralysis, Scwnce, 132 958-959 Ferguson, E W (1924) Deaths from tick paralysas xn human beings, M e d J Aunt, 2 346-348 Force, L and J Esvan (1968) M6mngoradlcuhte avec eryth6ma local survenant apres pJqure de tJque, Presse reed, 76 1571-1572 Foster, B (1931) A tick m the au&tory meatus, M e d J Aust, l 15-16 Hailer, J S and J A Fabara (1972) Tick paralysis, Amet J Dis ChaM, 124 915-917 Hamilton, D G (1940) Tick paralysis - - A dangerous &sease m children, Med J Aunt, I 759-765 H a m s , J B , E Karlsson and S Thesleff (1973) Effects of an isolated toxin from Austrahan Tiger snake (Notechts scutatus 3cutatus) venom at the mammalmn neuromuscular junction, Brtt J Pharmaeol, 47 141-146 H a m s , J B , M A Johnson and E Karlsson (1975) Pathological responses of rat skeletal muscle to a single subcutaneous anlect~on of a toxin isolated from the venom of the Austrahan Tiger snake, Notechls scutatu~ ~cutatu~, Chn exp pharm Phys, 2 383-404 Kalre, G H (1966) Isolation of tack paralysis toxin from lxodes holoeyclus, ToMeon, 4 91-97 Lagos, J C and R E Thles (1969) Tick paralysis without muscle weakness, .4reh Nemol, 21 471474 Lechevaher, B , J P Houttewlle and J N Blet (1974) Paralysae oculazre apr~s p~qfire de tlque a la pauplere mfeneure, Presse M e d , 3 456 Moorhouse, D E (1967) The attachment of some Ixo&d ticks to their natural hosts In Proc Setond lnt Congr Aearology, pp 319-327 Moorhouse, D E and R J Tatchell (1969) Histological responses of cattle and other ruminants to the recent attachment of Ixo&d larvae, J med Entomol, 6 419-422 Murnaghan, M F (1960) Site and mechamsm of tlck paralys~s, Setenee, 131 418-419 Pearn, J H (1966) A Case of tick paralysis with myocardltls, M e d J A u s t , 1 629-630 Rose, I (1954) A rewew of t~ck paralysis, Canad reed .4~s J , 70 175-176 Sax, D S and J Majlszenkzer (1971) Tick b~te m Parkmson's disease, New Engl J M e d , 285 292 293 Sutherst, R W and D E Moorhouse (197l) Irodes holoevelus larvae and "scrub-itch'" m Southeast Queensland, Sousthea~t Astan J trop reed Publ HIth , 2 82-83 Tatchell, R J and D E Moorhouse (1970) Neutrophfls--Thear role m the formation of a tick feeding lesion, Sewnee, 167 1002-1003 Tomkms, J (1963) The treatment of t~ck b~te m Austraha, Ann gen Pract, 8 92-95 Trmca, J C (1964) Insect allergy m Austraha - - Results of a five-year survey, M e d J Aunt, 2 659-663
37
N E U R O M U S C U L A R P A R A L Y S I S C A U S E D BY T I C K E N V E N O M A T I O N
JOHN PEARN Department of Chtld Health, Royal Chtldren's Hospttal, Brtsbane (Austraha) (Received 28 March, 1977)
SUMMARY The Austrahan scrub-tick Ixodes holocyclus causes a series of slgmficant toxic effects m its victims The most ~mportant feature of tick envenomatlon is neuromuscular paralysis Chddren poisoned by ticks may mamfest only local motoneural effects, usually facml paralysis Progressive ascending flaccid paralysis occurs if the removal of an embedded tick is delayed The specific neurological features of tick-bite are discussed m the hght of a series of 6 children who all showed signs of t~ck paralysis Tick venom is known to slow nerve conduction, and may have a botullnum-hke effect at the neuromuscular.lunctlon The hterature on the neurological effects of tlck-envenomatlon is rewewed
INTRODUCTION Envenomatlon by the Austrahan scrub-tick, Ixodes holocyclus, causes profound neuromuscular paralysis The venom as extremely potent Envenomatlon of humans following tick-bite is well recognized from Austraha (Ferguson 1924, Hamilton 1940, Pearn 1966), from North America (Costa 1952, Hailer and Fabara 1972, DeBusk and O ' C o n n o r 1972), from Europe (Force and Esvan 1968, Lechevaher, Houttevllle and Blet 1974), and from Africa (Editorial Brtt med J 1969) Children particularly are affected, and child deaths from bulbar and respiratory paralysis, although now rare, are always a threat if the embedded tick is not disdiscovered, or if the possibility of tick envenomatlon is not considered in the differential diagnosis of an acutely weak chdd There is a particular risk if a chdd returns from overseas to an area where ticks are unknown Tick bite may result in local or generalized allergic reactions (Trlnca 1964,
Address for reprints Department of Chdd Health, Royal Chddren's Hospital, Herston, Brisbane, Australia 4029
Present
Present
Virtual complete paralysis one day Complete areflexla D T R after removal of the tick Severe reappeared four days paralytic squint No bulba~ after removal of t~ck involvement cllmcally Complete areflexia D T R reappeared on Day 11 after tick removal
Normal
Ascending flaccid paralys~s By Day 4 unable to sit or stand Respiration purely dlaphragmatic Bdateral pupdlary ddatation
No signs of generalized weakness
Case 3 3-year-old girl
Case 4 6-year-old girl
Marked
Case 6 3-year-old girl
Complete areflexla
Absent
Case 5 Moderate weakness of lower hmbs Normal 3-year-old boy but able to stand and walk at all t~mes Some dysarthna
Progressive ascending flaccid paralysis Bulbar paralysis on Day 3 after tick removal, with respiratory difficulty
Present
Gross bilateral facial palsy
Present
Facial weakness
Marked
Absent
L sided ptosls L Bell's palsy
Present
Case 2 2-year-old girl
Ankle D T R absent Knee D T R hyporeflexic Upper limb D T R hyporeflexlc
Total paralysis of lower limbs Generahzed hypotonm Unable to hft arms Hand grip weak Poor head control
PtosJs
Case 1 3-year-old girl
Deep tendon reflexes
Peripheral muscle paralysis
Case
10 rag/100 ml, sugar 70 mg/ 100 ml No response to i v edlophomum, l v antlvenene given with reversal of neurological signs commencing within 1 hi Complete recovery
C S F No cells/ram ~ Protein
25 mg/100 ml, sugar 80 mg, 100 ml
C $ F No cells/mm ~ Protem
Tick embedded behind left ear, child presented because ot "unusual facial appeaiance
Presented with stridoi Complete recovery 2 ~eeks after removal of tick
Still weak 7 days after removal of the tick
No ophthalmoplegm Complete recovery 7 days after removal of tick
Notes
CLINICAL DETAILS OF N E U R O L O G I C A L SIGNS D U E TO E N V E N O M A T I O N BY THE A U S T R A L I A N SCRUB-TICK
TABLE 1
39 B a n f i e l d 1966, S u t h e r s t a n d M o o r h o u s e 1971), in t h e z o o n o t l c t r a n s m i s s i o n o f t y p h u s ( A n d r e w , B o n n i n a n d W i l l i a m s 1946), m y o c a r d l t i S ( P e a r n 1966) a n d local i n f e c t i o n a n d i n d u r a t i o n at the bite site ( T o m k l n s 1963) It is t h e p u r p o s e o f this r e p o r t t o r e v i e w t h e specific n e u r o m u s c u l a r c o m p l i c a t i o n s o f tick e n v e n o m a t l o n CASE REPORTS Six new cases of paralysis caused by the Austrahan scrub-tick were encountered between 1971-1975 mcluswe All occurred m chddren under the age of seven years Cllmcal detads of paralytic features are shown m Table 1 One child presented with a left Bell's palsy with the tick embedded behind the left ear Four children had marked generalized signs of progressive ascending flaccid paralysis which recovered spontaneously - - all children were nursed beside respirators and a policy of watchful antJopatzon employed One chdd (Case 6 - - see Fig 1) became severely paralysed with bulbar involvement, and was given canine anti-tick antlvenene (Commonwealth Serum Laboratories 1974) w~th satisfactory results - - th~s latter case also recovered completely without sequelae
/
Fig 1 Three-year-old gzrl (14 3 kg) with severe neuromuscular paralysis, 3 days after removal of a scrub-tick (Ixodes holocyclus) from the occipital region of the scalp Ptosls and foot-drop are evident Bulbar paralysis developed several hours later
40 DISCUSSION The scrub-tick Ixodes holo&~ lus (Fig 2) Js common throughout coastal Austraha, m heavily infested areas numerous domestic pets die each year from the paralytIc effects of its toxin The hfe-cycle consists of four stages - - egg, larva, nymph and adult - - but the bate of the gravld females only ~s sagmficant from the point of view of neuromuscular paralysas (Moorhouse 1967, Berry 1974) The hypostome penetrates the skin and the tack progressively burrows into the epidermis causing the so-called "feeding lesion" (Moorhouse and Tatchell 1969, Tatchell and Moorhouse 1970) It is from this s~te that the toxin-loaded salivary fluId (Kaare 1966) &ffuses to produce its local and systemic effects The North American wood tick, Dermacentot andetaom, and the common dog tick, Dermacentor vartabths, also cause human paralysas (Costa 1952, DeBusk and O'Connor 1972), improvement m muscle power after removal of these latter tacks seems to be much qmcker than that observed m cases envenomated by the Australian Ixodes holoo'clus (Costa 1952, Murnaghan 1960) Nevertheless, mortality from paralysis m a Cana&an seraes was 12 Yo (Rose 1954) A feature of the paralysis produced m children by Ixodea holocvclus is that ~t continues to progress even after removal of the embedded tick (see Case 6, and Pearn 1966) The venom may act locally on nerves by diffusion from a contiguous sate of attachment, usually the facml nerve is involved m this phenomenon as the ticks often
Fig 2 The Austrahan scrub-tick, lxodes holocyclus Fully engorged female, removed from a dog showing early s~gns of neuromuscular paralyszs
41 e m b e d m o r b e h i n d the ear ( F o s t e r 1931, Crossle 1932, A r t h u r 1965, P e a r n 1966) C o n s i d e r a b l e interest s u r r o u n d s the possible m o d e o f a c t i o n o f the v e n o m M u r n a g h a n (1960) suggested t h a t there were 2 possible sites o f a c t i o n - - one on nerve c o n d u c t i o n itself with greatly reduced nerve action potentmls, a n d a second b o t u h n u m hke effect preventing the release o f acetylchohne Synthesis a n d storage o f acetylc h o h n e at the small t e r m i n a l m o t o r fibres seemed to be unaffected, at least for D e r m a ¢ e n t o r a n d e r s o m v e n o m C h e r m g t o n a n d S n y d e r (1968) a n d H a i l e r a n d F a b a r a (1972) also f o u n d r e d u c e d nerve c o n d u c t i o n velocmes m a 5-year-old girl p a r a l y s e d by an umdentlfied tick C h e r m g t o n a n d S n y d e r (1968) felt that no defect was present at the n e u r o m u s c u l a r j u n c t i o n O t h e r w o r k e r s (Lagos a n d Thles 1969, Esplln, Phllhp a n d Hughes 1960) have suggested that the v e n o m has a b~phaslc a c t i o n - - l n m a l l y on the g a m m a system affecting muscle spindles, a n d later affecting nerve c o n d u c t i o n Suggestions t h a t tick v e n o m m a y mvolve the g a m m a efferents are s u p p o r t e d by the recent findings that l e v o d o p a - c o m p e n s a t e d P a r k m s o m a n patients can suffer acute P a r k m s o m a n crises after tlck e n v e n o m a t l o n (Sax a n d M a j l s z e n k l e r 1971, C u l e b r a s 1971) There is one r e p o r t suggesting that tick venom m a y have a d~rect effect on muscle (Boffey 1973) It is lnterestmg m this regard to note that the n e u r o t o x m notexln f r o m the A u s t r a l i a n T~ger snake also has a b o t u h n u m - h k e effect as well as a d~rect m y o t o x l c a c t i o n ( H a m s , K a r l s s o n a n d Thesleff 1973, Harris, J o h n s o n a n d K a r l s s o n 1975) L~ke the different p a t h o p h y s l o l o g l c a l actions o f different snake venoms it is hkely that different species o f t~ck vary m the way m which their v e n o m causes the vamous neurological signs o f e n v e n o m a t l o n The neuroparalyt~c effects o f the v e n o m are n o t species-specific Dogs, cats a n d even p a r r o t s ( D o m r o w a n d D e r r i c k 1965) are affected This non-selectwe a c t i o n offers c o n s i d e r a b l e scope for further l a b o r a t o r y investigation o f ~ts neurotoxlc effects ACKNOWLEDGEMENTS
The author thanks Drs G Bourke, N Chalk, R O'Redly and R Tlernan for gracious permission to review details of cases under their care, the author also thanks the Supermtendent, Mater Mlserlcordme Children's Hospital, Brisbane, for permission to pubhsh chmcal photographs
REFERENCES Andrew, R , Bonmn, J M and S Wflhams (1946) Tick typhus m North Queensland, M e d J .,lust, 2 253-258 Arthur, D R (1965) Ticks m Egypt m 1500 B C ? Nature (Lond), 206 1060-1061 Banfield, J F (1966) Tick bites m Man, M e d J A u s t , 2 600-601 Berry, F B (1974) More deadly than the male, M e d TmTes, 102 23-27 Boffey, G C (1973) Creatme phosphokmase elevation m a case oft~ck paralysis, Canad meal Ass J , 108 866-868 Chermgton, M and R D Snyder (1968) Tick paralysis - - Neurophyslologlc studies, New Engl J M e d , 278 95-97 Commonwealth Serum Laboratories (1974) Tick Antlvenene In CSL Medtcal Handbook, CSL Pubhcat~ons, Parkvllle, V~ctona, Austraha, pp 204-206 Costa, J A (1952) T~ck paralysis on the Atlantic seaboard, Amer J Dts ChtM, 83 336--347
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