Population dynamics of the minute intestinal trematode Haplorchis pumilio following experimental infection of young dogs

TY - ABST

T1 - Population dynamics of the minute intestinal trematode Haplorchis pumilio following experimental infection of young dogs

AU - Nissen, Sofie

AU - Nguyen, Lan Anh

AU - Thamsborg, Stig Milan

AU - Dalsgaard, Anders

AU - Johansen, Maria Vang

PY - 2011

Y1 - 2011

N2 - Fishborne zoonotic trematodes (FZT) are highly prevalent in Southeast Asia. Recent studies on domestic animal’s role in the transmission of FZT in Northern Vietnam found that the most prevalent FZT was Haplorchis pumilio. The importance of dogs, cats and pigs was assessed, and dogs were found to have the highest intensity of infection and contribute the most to the contamination of the environment with FZT eggs in the Nam Dinh province - a highly endemic area for FZTs. Given the free roaming and fish-eating behaviour of many dogs in rural Vietnam controlling the infection in dogs represents a major challenge. In particular knowledge is needed on the importance of the dog as reservoir to make evidence-based recommendations for control of FZT. On this background, we conducted an experimental infection in dogs with H. pumilio to elucidate population dynamics and host reactions. Eight household-reared dogs (3-6 months old), were each orally infected with 500 metacercariae (mainly H. pumilio) obtained by artificially digestion of naturally infected fish. Another eight dogs were included as uninfected controls. Faecal examination for eggs was performed twice weekly using a sieving and sedimentation technique, temperature and weight of the dogs were measured as was total white blood cells, eosinophils and microhaemotocrit values. Subsets of dogs were examined post-mortem for presence of adult FZT at three different time points post infection. Patent infections established in all eight infected dogs. The worm establishment ranged from 3 – 24% (mean 12%). Faecal egg excretion was measured in all eight infected dogs but no more than 2 eggs per g (epg) were found at any time. Infections lasted for at least two months as documented by the presence of adult flukes in three dogs necropsied on day 58 post infection. Following dissection and sectioning of the small intestine and caecum into four parts, the predilection site of the flukes was identified as the lower part of the jejunum. The results of the hematological tests did not differ between the infected and uninfected group. Further, no clinical symptoms were observed in the infected group and no macroscopic pathological changes could be assigned to the trematode infections, neither did histopathological examination of the intestine reveal any differences between the infected and the control dogs. This pilot study provides basic knowledge on the establishment, duration and location of H. pumilio infection in the intestine. Further population dynamic studies are needed before recommendations for prevention and control can be provided.

AB - Fishborne zoonotic trematodes (FZT) are highly prevalent in Southeast Asia. Recent studies on domestic animal’s role in the transmission of FZT in Northern Vietnam found that the most prevalent FZT was Haplorchis pumilio. The importance of dogs, cats and pigs was assessed, and dogs were found to have the highest intensity of infection and contribute the most to the contamination of the environment with FZT eggs in the Nam Dinh province - a highly endemic area for FZTs. Given the free roaming and fish-eating behaviour of many dogs in rural Vietnam controlling the infection in dogs represents a major challenge. In particular knowledge is needed on the importance of the dog as reservoir to make evidence-based recommendations for control of FZT. On this background, we conducted an experimental infection in dogs with H. pumilio to elucidate population dynamics and host reactions. Eight household-reared dogs (3-6 months old), were each orally infected with 500 metacercariae (mainly H. pumilio) obtained by artificially digestion of naturally infected fish. Another eight dogs were included as uninfected controls. Faecal examination for eggs was performed twice weekly using a sieving and sedimentation technique, temperature and weight of the dogs were measured as was total white blood cells, eosinophils and microhaemotocrit values. Subsets of dogs were examined post-mortem for presence of adult FZT at three different time points post infection. Patent infections established in all eight infected dogs. The worm establishment ranged from 3 – 24% (mean 12%). Faecal egg excretion was measured in all eight infected dogs but no more than 2 eggs per g (epg) were found at any time. Infections lasted for at least two months as documented by the presence of adult flukes in three dogs necropsied on day 58 post infection. Following dissection and sectioning of the small intestine and caecum into four parts, the predilection site of the flukes was identified as the lower part of the jejunum. The results of the hematological tests did not differ between the infected and uninfected group. Further, no clinical symptoms were observed in the infected group and no macroscopic pathological changes could be assigned to the trematode infections, neither did histopathological examination of the intestine reveal any differences between the infected and the control dogs. This pilot study provides basic knowledge on the establishment, duration and location of H. pumilio infection in the intestine. Further population dynamic studies are needed before recommendations for prevention and control can be provided.

M3 - Conference abstract in proceedings

BT - Population dynamics of the minute intestinal trematode Haplorchis pumilio following experimental infection of young dogs

T2 - The 96 Years of Opistorchiasis: Past, Present and Future. International Congress of Liver Flukes

Y2 - 7 March 2011

ER -