Memórias do Instituto Oswaldo Cruz Fundação Oswaldo Cruz, Fiocruz ISSN: 1678-8060 EISSN: 1678-8060 Vol. 97, Num. 1, 2002, pp. 51-52

Mem Inst Oswaldo Cruz, Rio de 
  Janeiro, Vol. 97(1) 2002, pp. 51-52
Ecological Data of Travassosnema 
  travassosi travassosi (Dracunculoidea: Guyanemidae) from the Humour of the 
  Eyes of Acestrorhynchus lacustris from Tibagi River, Paraná, Brazil 
   
Ângela Teresa Silva-Souza/+, 
  Aurélia Saraiva*  
Departamento de Biologia Animal e Vegetal, CCB, 
  Universidade Estadual de Londrina, Caixa Postal 6001, 86051-990 Londrina, PR, 
  Brasil *Departamento de Zoologia e Antropologia, Faculdade de Ciências, 
  Universidade do Porto, Porto, Portugal 

  +Corresponding author. Fax: +55-43-371.4207. E-mail: ateresa@uel.br 
  
Received 28 March 2001 

  Accepted 13 September 2001 
Code Number: oc02008
Data obtained between 1990 and 1995 provide, 
  for the first time, ecological information of the parasitic nematode Travassosnema 
  travassosi travassosi Costa, Moreira 
  & Oliveira, 1991 from Acestrorhynchus 
  lacustris (Characiformes: Acestrorhynchidae) 
  collected in the Tibagi River, Sertanópolis, Paraná, Brazil. These 
  nematode occurred with low prevalences (7.7% to 28.6%) and intensities (1 to 
  3) during almost the whole year. The observation of mature females throughout 
  the year indicate that liberation of larvae can occur during all the year around. 
  This is the first report on the occurrence of T. 
  travassosi travassosi inside the eyes. 
  These nematodes were mostly located in humour of the eyes (87% of cases), being 
  less frequently detected in tissues behind the eyes (13% of cases).  
  
 Key words: Travassosnema travassosi travassosi 
  - Nematoda - parasites - Acestrorhynchus lacustris - Tibagi River - Paraná 
  - Brazil  
The genus Travassosnema Costa Moreira 
  & Oliveira 1991 (Dracunculoidea: Guyanemidae) is represented by medium sized 
  nematodes with a rounded cephalic end, without a buccal capsule and with the 
  oesophagus divided into an anterior muscular and a posterior glandular portions. 
  The posterior glandular portion of oesophagus is provided with a long dorsal 
  appendix extending posteriorly, a feature that makes this genus easily distinguishable 
  from the genus Guyanema Petter, 1974 (Costa et al. 1991, Moravec 1998). 
   
 Two subspecies of the only species T. travassosi 
  Costa Moreira & Oliveira, 1991 are known to occur in South American 
  freshwater fishes, Acestrorhynchus lacustris Reinhardt, 1874 (Characiformes: 
  Acestrorhynchidae) being the only known host of these parasites (Moravec 1998, 
  Vicente & Pinto 1999). T. travassosi travassosi Costa Moreira & 
  Oliveira, 1991 was detected in the tissues behind the eyes (orbits) from fishes 
  from the Três Marias Reservoir on the São Francisco River, State 
  of Minas Gerais, Brazil (Costa et al. 1991), while T. travassosi paranaensis 
  Moravec Kohn & Fernandes, 1993 was detected in the abdominal cavity from 
  fishes of the Paraná River near Guaíra, Brazil (Moravec et al. 
  1993). No data have been published on the prevalence and the intensity of infection 
  of these nematodes.  
 During a study of helminth parasites of the 
  eyes of A. lacustris conducted between 1990 and 1995 in the Tibagi River, 
  Paraná, Brazil, the dracunculoid nematode T. travassosi travassosi 
  was observed. Data related to ecological indexes of prevalence and intensity 
  of infection of these parasites are evaluated in this paper. 
 MATERIALS 
  AND METHODS 
Nematodes were collected from both the orbits 
  and humour of the eyes of A. lacustris caught by waiting nets in Tibagi 
  River, Sertanópolis, Paraná, Brazil near the confluence to Paranapanema 
  River (22º30'S and 51º00'W). The study area became a semi-lotic system 
  after the construction of Capivara dam, on the Paranapanema River, in 1975. 
  Fish samples were collected between April 1990 and February 1991 (n = 51; body 
  length: 14.3 - 27.6 cm), August 1992 and July 1993 (n = 122; body length: 10.6 
  - 27.5 cm) and April 1994 and May 1995 (n = 46; body length: 10.4 - 23.9 cm). 
  Samples were obtained occasionally during these periods excluding from August 
  1992 to July 1993 when samples were obtained monthly.  
Nematodes were fixed and stored in 70% ethanol 
  and cleared in glycerine for examination. 
RESULTS 
    
The 
  prevalence of T. travassosi travassosi found in A. lacustris is 
  shown in the Table. The intensity of infection 
  was usually low (1 to 3 specimens) but, in December 1992, 13 and 26 nematodes 
  were detected in the humour of the eyes of two hosts. In fact, T. travassosi 
  travassosi was mostly located inside the eyes (87%) in the humours and, 
  in the majority of cases, both eyes were infected (Fig. 
  1). Less frequently (13%), the nematodes were found in the tissues behind 
  the eyes, i.e. orbits.  
The prevalence in the samples carried 
  out monthly between August 1992 and July 1993 is shown in Fig. 
  2. These results indicate that specimens of T. travassosi travassosi 
  occur in A. lacustris during almost all the year without a marked seasonal 
  cycle. Only 2% of nematode specimens were males, and mature females with uterus 
  containing larvae were observed throughout the year, indicating that the liberation 
  of larvae could occur in this locality during all the year. Excluding these 
  small larvae (probably first-stage larvae), other larval stages were never observed 
  in the eyes. 
DISCUSSION 
  
This is the first report on the occurrence of 
  T. travassosi travassosi in the humours of the eyes. This observation 
  seems to be important because helminth eyes parasites usually cause opacity 
  of the eye lenses and even blindness, symptoms that usually decrease the growth 
  rates due to fish difficulties to localize food and also reduction of the fish 
  population due to smaller fish ability to escape to predators.  
In the present study, we observed that the prevalence 
  and the intensity of infection were much higher inside the eyes than in the 
  orbits where these nematodes were first detected. These parasites were present, 
  in the study area, usually with low values of prevalence and intensity of infection 
  during almost the whole year.  
These parasites, both males and mature females, 
  were located in orbits and humours of the eyes in the examined specimens of 
  A. lacustris. However, it is possible that, as occurs with other dracunculoids, 
  other organs can also be infected by T. travassosi travassosi. For this 
  reason a detailed helminthological examination of the other specimens of A. 
  lacustris from Tibagi River will be interesting in the future.  
The life cycle of T. travassosi travassosi 
  undoubtedly involves an intermediate host. The family Guyanemidae shows some 
  affinities with the closely related dracunculoid families Skrjabillanidae and 
  Daniconematidae (Moravec & Køie 1987, Molnár & Moravec 
  1994). In skrjabillanids, the first-stage larvae released from the viviparous 
  nematodes are taken up by the intermediate host, hematophagous branchiurids 
  (Argulus spp.), and third-stage larvae are inoculated by these invertebrates 
  into the vertebrate definitive host (Moravec 1994, 1998, Molnár & 
  Székely 1998, Moravec et al. 1998). According to Molnár and Moravec 
  (1994), Molnár (1997) and Moravec et al. (1999), dani-conematids seem 
  to have, because of the morphological similarity of these nematodes, a life 
  cycle very similar to skrjabillanids, i.e. haematophagous branchiurids could 
  also serve as intermediate hosts of these nematodes. For the same reason it 
  seems that we could speculate the same for guyanemids. This hypothesis is corroborated 
  by Moravec (1998) who stated that probably some blood-sucking invertebrate ectoparasites 
  probably serve as intermediate hosts of T. travassosi travassosi. The 
  elucidation of the life cycle of these nematodes requires a detailed study including 
  the identification of the blood-sucking ectoparasites that occur in the study 
  area and the search for larval stages of these nematodes in scales, skin and 
  subcutaneous tissues of A. lacustris. 
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© 2002  
  Instituto Oswaldo Cruz - Fiocruz

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