[Gnathostoma (Spirurida: Gnathostomatidae) infection in the tigerfish Hoplias microlepis: prevalence, correlation with fish size, hosts, and public health implications].
BACKGROUND
Human gnathostomiasis has been reported in Ecuador since the early 1980s, when natural infections by Gnathostoma third larval stages were found in muscles of the second intermediary host, Hoplias microlepis (tigerfish). In Ecuador, this zoonotic disease is occasionally detected in humans, and its monitoring and eco-epidemiological assessment is of particular interest for its detection and control.


OBJECTIVE
The most recent evidence is provided with respect to natural infections by Gnathostoma as it occurs in the tigerfish (Hoplias microlepis), including insights into its biological cycle.


METHODS
A total of 74 fish were collected from two localities (rice fields-wetlands and local fish market) of Samborondón County (Guayas Province). Each was examined for the presence of Gnathostoma in muscle of Hoplias microlepis. The abundance intensity and prevalence of parasites was estimated. Statistical comparisons between the two sites and correlations of parasite load versus fish size were conducted.


RESULTS
The infection prevalence by Gnathostoma was 69% (95% CI: 57-78%). The overall abundance intensity of parasites averaging the 2 sites was 1.7 larvae per fish. The proportion of infected fish was higher in rice fields (77%) when compared to those from the local fish market (62%). No statistically significant differences between the abundance intensity and prevalence were found between the sites (p>0.05). Parasite load and fish length were significantly correlated (Spearman p<0.05).


CONCLUSIONS
Gnathostomiasis is a prevalent zoonosis in coastal Ecuador, and its etiologic agent is commonly found in the second intermediary host. Several Neotropical mammals are candidates as definitive reservoir hosts in the Gnathostoma biological cycle.
Jiménez
Pedro J
PJ
Fundación Ecuatoriana para el Estudio de Mamíferos Marinos, Guayaquil, Ecuador.
Alava
Juan José
JJ
D000818:Animals; D001835:Body Weight; D002415:Cats; D004197:Disease Reservoirs; D004484:Ecuador; D005393:Fish Diseases / Q000453:epidemiology* / Q000469:parasitology; D005399:Fishes / Q000033:anatomy & histology / Q000469:parasitology*; D016266:Food Parasitology; D006039:Gnathostoma / Q000254:growth & development / Q000302:isolation & purification*; D006801:Humans; D007814:Larva; D008018:Life Cycle Stages; D008322:Mammals / Q000469:parasitology; D018482:Muscle, Skeletal / Q000469:parasitology; D015995:Prevalence; D011634:Public Health; D017205:Spirurida Infections / Q000453:epidemiology / Q000469:parasitology / Q000635:transmission / Q000662:veterinary*; D015047:Zoonoses