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Experimental transmission of Dipetalonema dracunculoides (Cobbold 1870) by Rhipicephalus sanguineus (Latreille 1806)
Veterinary Parasitology, 47 (1993) 339-342 Elsevier Science Publishers B.V., Amsterdam
339
Short Communication Experimental transmission of Dipetalonema dracunculoides ( Cobbold 1870 ) by Rhipicephalus sanguineus ( Latreille 1806 ) A.S. Olmeda-Garcia a, J.A. Rodriguez-Rodrigueza and F.A. Rojo-V~izquez b aDepartamento Patologia Animal I, Facultad de Veterinaria, UniversidadComplutense, 28040 Madrid, Spain bDepartamento Patologia Animal, Facultad de Veterinaria, Universidadde Le6n, Ledn, Spain (Accepted 19 November 1992)
ABSTRACT Olmeda-Garcia, A.S., Rodriguez-Rodriguez, J.A. and Rojo-V~izquez, F.A., 1993. Experimental transmission of Dipetalonema dracunculoides ( Cobbold 1870 ) by Rhipicephalus sanguineus (Latreille 1806. Vet. Parasitol., 47: 339-342. A dog naturally infected with Dipetalonema dracunculoides and having a microfilaremia of 6050 microfilariae per mm 3 of blood was used as source of infection. Experimentally cultivated nymphs of Rhipicephalus sanguineus were fed on the donor dog. Once engorged, ninety-three nymphs were removed and kept at 30°C and RH 90% until they moulted to the adult stage. To study the development of microfilariae in the vector, ten ticks were dissected at Day 37 post-infection. Adult infected ticks were fed on two uninfected dogs. The observed pre-patent periods were 69 and 76 days. Trans-stadial transmission ofDipetalonema dracunculoides by Rhipicephalus sanguineus was demonstrated.
INTRODUCTION
Dipetalonema dracunculoides was first reported in Spain by Ortega-Mora and Rojo-V~izquez (1988) and is considered to be the most widespread filarid infection of dogs in the country (Rojo-V~izquez et al., 1990). The life cycle of the parasite in the invertebrate host is not well known. The larvae have been found in Hippobosca longipennis removed from a dog infected with D. dracunculoides (Nelson, 1963 ). Infective stages (L3) removed Correspondence to: A.S. Olmeda-Garcia, Departamento Patologia Animal I, Facultad de Veterinaria, Universidad Complutense, 28040 Madrid, Spain.
© 1993 Elsevier Science Publishers B.V. All rights reserved 0304-4017/93/$06.00
340
A.S. OLMEDA-GARdA ET AL.
from the brown tick, Rhipicephalus sanguineus, were described by Bain ( 1972 ). Davadan ( 1988 ) and Rodriguez-Rodriguez et al. ( 1989 ) considered this tick to be a vector ofD. dracunculoides. Since we have already described the development of D. dracunculoides in R. sanguineus (Olmeda-Garcia and Rodriguez-Rodriguez, 1990a,b ), the purpose of this study was to confirm the possible role of the tick R. sanguineus in the life cycle. MATERIAL AND METHODS
The specimens of R. sanguineus used in the study came from a laboratory colony maintained in our department, as described by Bailey (1960). During the periods between feeding, the ticks were maintained at 30 ° C and 90% RH. The donor dog was an Iberian H o u n d carrying a natural infection of D. dracunculoides. The level of microfilaremia was of 6050 microfilariae per m m 3 of blood. Ninety-three parasite-free nymphs, which were the second generation derived from a wild-caught R. sanguineus female, were fed on the donor dog. An elastic vest was fitted to permit removal of engorged nymphs. After reaching the adult stage, the ticks were divided into three groups. Group A constituted 28 females and 15 males, Group B 28 females and 12 males, and Group C 6 females and 4 males ( 10% of infected ticks). Two 6-month-old female Beagle dogs, reared under conditions that prevented parasite infections, were used for the experimental infection. Haematological analysis using the membrane-filtration technique (Difilttest ® ) was carried out monthly to confirm that there was no microfilaremia. Thirty-seven days post-infection, ticks from Group A were fed on uninfected dog No. 1 and those from Group B on dog No. 2 for 7 days. From that time onwards, the membrane-filtration technique was carried out every week until the dogs were 12 months old. When the ticks were removed they were dissected. The third group of ticks (Group C) was dissected in phosphate-buffered saline solution, pH 7.2, using a stereomicrocope 37 days post-infection to confirm the development of the microfilariae to the third-stage larvae. Dog No. 2 was necropsied at 6 months post-infection. The procedure followed for the necropsy was that described by de Aluja ( 1985 ). RESULTS
The first microfilariae were observed 69 days post-infection (p.i.) in dog No. 2 and 76 days p.i. in dog No. 1. At necropsy, six female and five male adult worms were present in the abdominal cavity of dog No. 2.
TRANSMISSION OF DIPETALONEMA DRACUNCULOIDES BY RH1PICEPHALUS SANGUINEUS
341
Two females and one male o f the ticks in Group C harboured third-stage larvae. Seven larvae were removed, one from the male and two and four from the females. No larvae were found in the adult engorged ticks in Groups A (23 females and 12 males) or B (22 females and 8 males). DISCUSSION The results o f this study confirm that the tick R. sanguineus is a vector of D. dracunculoides (Bain, 1972; Davadan, 1988; Rodriguez-Rodriguez et al., 1989). The n e m a t o d e is transmitted trans-stadially from n y m p h to adult. The prepatent period of 2-3 m o n t h s was similar to that o f Dipetalonema reconditum: (Farnell and Faulkner, 1978; L i n d e m a n n and McCall, 1984). Nelson ( 1963 ) found that the distribution ofD. dracunculoides overlapped with the distribution of H. longipennis in African dogs and hyaenas, suggesting that the hippoboscid flies could transmit D. dracunculoides. The possibility that D. dracunculoides can develop to the infective stage in the tick R. sanguineus is of great importance in the transmission of this nem a t o d e parasite. The widespread distribution of D. dracunculoides and R. sanguineus in Spain can be correlated. However, more studies are needed to define the epidemiology o f D. dracunculoides infection in dogs.
REFERENCES Bailey, K.P., 1960. Notes on the rearing of Rhipicephalus appendiculatus and their infection with Theileriaparva for experimentaltransmission. Bull. Epizoot. Dis. Africa, 8: 33-43. Bain, O., 1972. Recherches sur la morphogrn6se des filaries chez l'h6te interm6diaire. Ann. Parasitol. Hum. Comp., 47 (2): 251-303. Davadan, A., 1988. Contribution a l'rtude de l'infestation parasitaire du chien par Dipetalonema dracunculoides. Th. Doc. Vrt., Toulouse, 149 pp. De Aluja, A.S., 1985. Necropsias en animales domrsticos. 1st edn. Compafila Editorial Continental, S.A., Mexico. Farnell, D.R. and Faulkner, D.R., 1978. Prepatent period of Dipetalonema reconditurn in experimentally infected dogs. J. Parasitol., 64 (3): 565-567. Lindemann, B.A. and McCall, J.W., 1984. Experimental Dipetalonema reconditum infections in dogs. J. Parasitol., 70( 1): 167-168. Nelson, G.S., 1963. Dipetalonema dracunculoides (Cobbold, 1870) from a dog in Kenya with a note of its development in the louse Hippobosca longipennis. J. Helminthol., 37: 235-240. Olmeda-Garcia, A.S. and Rodriguez-Rodriguez,J.A., 1990a. Description des larves de Dipetalonema dracunculoides chez son vecteur. VII Int. Congr. Parasitology (ICOPA). J.M. Doby, Paris, p. 325. Olmeda-Garcia, A.S. and Rodriguez-Rodriguez,J.A., 1990b. D6veloppement de Dipetalonema dracunculoides chez Rhipicephalus sanguineus. VII Int. Congr. Parasitology (ICOPA). J.M. Doby, Paris, p. 1185.
342
A.S. OLMEDA-GARCIA ET AL.
Ortega-Mora, L.M. and Rojo-V~izquez, F.A., 1988. Sobre la presencia de Dipetalonema dracunculoides (Cobbold, 1870 ) en el perro en Espafia. Rev. Ib6r. Parasitol., 48 (2): 187-188. Rodriguez-Rodriguez, J.A., Olmeda-Garcia, A.S., Valc~ircel-Sancho, F. and G6mez-Bautista, M., 1989. Rhipicephalus sanguineus (Letrille, 1908 ) vector potencial de Dipetalonema dracunculoides (Cobbold, 1870). VI Congreso Nacional y I Congreso Ib6rico de Parasitologla. Caja de Ahorros de Salamanca, C~iceres, p. 229. Rojo-Vitzquez, F.A., Valc~ircel, F., Guerrero, J. and G6mez-Bautista, M., 1990. Prevalencia de la dirofilariosis canina en cuatro ~ireas geogr~ificas de Espafia. Med. Vet., 7(5 ): 297-305.
339
Short Communication Experimental transmission of Dipetalonema dracunculoides ( Cobbold 1870 ) by Rhipicephalus sanguineus ( Latreille 1806 ) A.S. Olmeda-Garcia a, J.A. Rodriguez-Rodrigueza and F.A. Rojo-V~izquez b aDepartamento Patologia Animal I, Facultad de Veterinaria, UniversidadComplutense, 28040 Madrid, Spain bDepartamento Patologia Animal, Facultad de Veterinaria, Universidadde Le6n, Ledn, Spain (Accepted 19 November 1992)
ABSTRACT Olmeda-Garcia, A.S., Rodriguez-Rodriguez, J.A. and Rojo-V~izquez, F.A., 1993. Experimental transmission of Dipetalonema dracunculoides ( Cobbold 1870 ) by Rhipicephalus sanguineus (Latreille 1806. Vet. Parasitol., 47: 339-342. A dog naturally infected with Dipetalonema dracunculoides and having a microfilaremia of 6050 microfilariae per mm 3 of blood was used as source of infection. Experimentally cultivated nymphs of Rhipicephalus sanguineus were fed on the donor dog. Once engorged, ninety-three nymphs were removed and kept at 30°C and RH 90% until they moulted to the adult stage. To study the development of microfilariae in the vector, ten ticks were dissected at Day 37 post-infection. Adult infected ticks were fed on two uninfected dogs. The observed pre-patent periods were 69 and 76 days. Trans-stadial transmission ofDipetalonema dracunculoides by Rhipicephalus sanguineus was demonstrated.
INTRODUCTION
Dipetalonema dracunculoides was first reported in Spain by Ortega-Mora and Rojo-V~izquez (1988) and is considered to be the most widespread filarid infection of dogs in the country (Rojo-V~izquez et al., 1990). The life cycle of the parasite in the invertebrate host is not well known. The larvae have been found in Hippobosca longipennis removed from a dog infected with D. dracunculoides (Nelson, 1963 ). Infective stages (L3) removed Correspondence to: A.S. Olmeda-Garcia, Departamento Patologia Animal I, Facultad de Veterinaria, Universidad Complutense, 28040 Madrid, Spain.
© 1993 Elsevier Science Publishers B.V. All rights reserved 0304-4017/93/$06.00
340
A.S. OLMEDA-GARdA ET AL.
from the brown tick, Rhipicephalus sanguineus, were described by Bain ( 1972 ). Davadan ( 1988 ) and Rodriguez-Rodriguez et al. ( 1989 ) considered this tick to be a vector ofD. dracunculoides. Since we have already described the development of D. dracunculoides in R. sanguineus (Olmeda-Garcia and Rodriguez-Rodriguez, 1990a,b ), the purpose of this study was to confirm the possible role of the tick R. sanguineus in the life cycle. MATERIAL AND METHODS
The specimens of R. sanguineus used in the study came from a laboratory colony maintained in our department, as described by Bailey (1960). During the periods between feeding, the ticks were maintained at 30 ° C and 90% RH. The donor dog was an Iberian H o u n d carrying a natural infection of D. dracunculoides. The level of microfilaremia was of 6050 microfilariae per m m 3 of blood. Ninety-three parasite-free nymphs, which were the second generation derived from a wild-caught R. sanguineus female, were fed on the donor dog. An elastic vest was fitted to permit removal of engorged nymphs. After reaching the adult stage, the ticks were divided into three groups. Group A constituted 28 females and 15 males, Group B 28 females and 12 males, and Group C 6 females and 4 males ( 10% of infected ticks). Two 6-month-old female Beagle dogs, reared under conditions that prevented parasite infections, were used for the experimental infection. Haematological analysis using the membrane-filtration technique (Difilttest ® ) was carried out monthly to confirm that there was no microfilaremia. Thirty-seven days post-infection, ticks from Group A were fed on uninfected dog No. 1 and those from Group B on dog No. 2 for 7 days. From that time onwards, the membrane-filtration technique was carried out every week until the dogs were 12 months old. When the ticks were removed they were dissected. The third group of ticks (Group C) was dissected in phosphate-buffered saline solution, pH 7.2, using a stereomicrocope 37 days post-infection to confirm the development of the microfilariae to the third-stage larvae. Dog No. 2 was necropsied at 6 months post-infection. The procedure followed for the necropsy was that described by de Aluja ( 1985 ). RESULTS
The first microfilariae were observed 69 days post-infection (p.i.) in dog No. 2 and 76 days p.i. in dog No. 1. At necropsy, six female and five male adult worms were present in the abdominal cavity of dog No. 2.
TRANSMISSION OF DIPETALONEMA DRACUNCULOIDES BY RH1PICEPHALUS SANGUINEUS
341
Two females and one male o f the ticks in Group C harboured third-stage larvae. Seven larvae were removed, one from the male and two and four from the females. No larvae were found in the adult engorged ticks in Groups A (23 females and 12 males) or B (22 females and 8 males). DISCUSSION The results o f this study confirm that the tick R. sanguineus is a vector of D. dracunculoides (Bain, 1972; Davadan, 1988; Rodriguez-Rodriguez et al., 1989). The n e m a t o d e is transmitted trans-stadially from n y m p h to adult. The prepatent period of 2-3 m o n t h s was similar to that o f Dipetalonema reconditum: (Farnell and Faulkner, 1978; L i n d e m a n n and McCall, 1984). Nelson ( 1963 ) found that the distribution ofD. dracunculoides overlapped with the distribution of H. longipennis in African dogs and hyaenas, suggesting that the hippoboscid flies could transmit D. dracunculoides. The possibility that D. dracunculoides can develop to the infective stage in the tick R. sanguineus is of great importance in the transmission of this nem a t o d e parasite. The widespread distribution of D. dracunculoides and R. sanguineus in Spain can be correlated. However, more studies are needed to define the epidemiology o f D. dracunculoides infection in dogs.
REFERENCES Bailey, K.P., 1960. Notes on the rearing of Rhipicephalus appendiculatus and their infection with Theileriaparva for experimentaltransmission. Bull. Epizoot. Dis. Africa, 8: 33-43. Bain, O., 1972. Recherches sur la morphogrn6se des filaries chez l'h6te interm6diaire. Ann. Parasitol. Hum. Comp., 47 (2): 251-303. Davadan, A., 1988. Contribution a l'rtude de l'infestation parasitaire du chien par Dipetalonema dracunculoides. Th. Doc. Vrt., Toulouse, 149 pp. De Aluja, A.S., 1985. Necropsias en animales domrsticos. 1st edn. Compafila Editorial Continental, S.A., Mexico. Farnell, D.R. and Faulkner, D.R., 1978. Prepatent period of Dipetalonema reconditurn in experimentally infected dogs. J. Parasitol., 64 (3): 565-567. Lindemann, B.A. and McCall, J.W., 1984. Experimental Dipetalonema reconditum infections in dogs. J. Parasitol., 70( 1): 167-168. Nelson, G.S., 1963. Dipetalonema dracunculoides (Cobbold, 1870) from a dog in Kenya with a note of its development in the louse Hippobosca longipennis. J. Helminthol., 37: 235-240. Olmeda-Garcia, A.S. and Rodriguez-Rodriguez,J.A., 1990a. Description des larves de Dipetalonema dracunculoides chez son vecteur. VII Int. Congr. Parasitology (ICOPA). J.M. Doby, Paris, p. 325. Olmeda-Garcia, A.S. and Rodriguez-Rodriguez,J.A., 1990b. D6veloppement de Dipetalonema dracunculoides chez Rhipicephalus sanguineus. VII Int. Congr. Parasitology (ICOPA). J.M. Doby, Paris, p. 1185.
342
A.S. OLMEDA-GARCIA ET AL.
Ortega-Mora, L.M. and Rojo-V~izquez, F.A., 1988. Sobre la presencia de Dipetalonema dracunculoides (Cobbold, 1870 ) en el perro en Espafia. Rev. Ib6r. Parasitol., 48 (2): 187-188. Rodriguez-Rodriguez, J.A., Olmeda-Garcia, A.S., Valc~ircel-Sancho, F. and G6mez-Bautista, M., 1989. Rhipicephalus sanguineus (Letrille, 1908 ) vector potencial de Dipetalonema dracunculoides (Cobbold, 1870). VI Congreso Nacional y I Congreso Ib6rico de Parasitologla. Caja de Ahorros de Salamanca, C~iceres, p. 229. Rojo-Vitzquez, F.A., Valc~ircel, F., Guerrero, J. and G6mez-Bautista, M., 1990. Prevalencia de la dirofilariosis canina en cuatro ~ireas geogr~ificas de Espafia. Med. Vet., 7(5 ): 297-305.