Change of serum transferrin receptor due to malarial infection, an experiment in Plasmodium gallinaceum infected chicken model.

BACKGROUND & OBJECTIVES: The serum transferrin receptor (sTfR) concentration in an individual reflects the extent of erythropoietic activity and is considered as an useful marker of iron deficiency independent of concurrent inflammation or infection. However, data on the impact of malaria on this parameter are ambiguous. METHODS: Here we performed an animal experiment to study the chronological change of serum transferrin receptor due to infection of Plasmodium gallinaceum. In this pilot study, we performed control experimental infection of P. gallinaceum to four newborn chicken from the same batch. We collected the venous blood samples from all chicken on Day 7 and 14. All samples were analysed for sTfR level by the immunoturbidimetric assay. RESULTS: The average level of sTfR level of the control chicken was 1.24 +/- 1.58 mg/L (range 0.18 to 3.52 mg/L). The average level of sTfR level of the experimental chicken on Day 7 was 5.42 +/- 2.19 mg/L (range 3.22 to13.94 mg/L). CONCLUSION: Although the trend of increase was observed but no significance was observed (p > 0.05). The results from this pilot study can be a good basic data for the further study in this area.

Vector competence of Aedes aegypti (L.) and Culex quinquefasciatus (Say) for Dirofilaria immitis (Leidy).

This study was performed to examine the vector competence of Aedes aegypti and Culex quinquefasciatus for Dirofilaria immitis. Eleven individual experiments were conducted in this study. Nonthaburi and Udon Thani strains of Ae. aegypti were allowed to feed on infected dogs that had 5,750 and 4,600 microfilariae (mW) per ml of blood, respectively. Three groups of Bangkok-strain Cx. quinquefasciatus were allowed to feed on dogs that had 4,800, 5,200, and 5,850 mf per ml of blood. Six groups of Liverpool-strain Ae. aegypti were allowed to feed on dogs with 1,650, 1,950, 3,350, 9,000, 9,250, and 11,550 mf per ml of blood. Three to 4% of Nonthaburi-strain, and 0-6% of Udon Thani-strain Ae. aegypti became infected and had infective-stage larvae (L3) of D. immitis in their probosces. Zero to 1 and 7% of Bangkok-strain Cx. quinquefasciatus had L3 in their probosces after taking blood meals with 4,800 and 5,850 mf per ml of blood, respectively. The percent-infected Liverpool-strain Ae. aegypti with L3 in their probosces were 3-12, 0-12, 10, 16, 7-19, and 0-21 after taking blood meals with 1,650, 1,950, 3,350, 9,000, 9,250, and 11,550 mf per ml of blood, respectively, when tested at different post-blood-feeding days. This study showed both Ae. aegypti and Cx. quinquefasciatus from Thailand can become vectors for D. immitis; however, Liverpool-strain Ae. aegypti are more likely to be competent vectors for D. immitis than Ae. aegypti and Cx. quinquefasciatus from Thailand. The percent infection rates of Ae. aegypti and Cx. quinquefasciatus with D. immitis in the field in Thailand need to be investigated, to confirm the role of these mosquitoes in the life cycle of D. immitis in nature.

A preliminary study on in vitro transmission of Dirofilaria immitis infective stage larvae by Aedes aegypti (L.) (Diptera: Culicidae).

This study was performed to study an in vitro transmission of infective stage larvae from the mosquito proboscis. There were five experiments with 949 mosquitoes. Liverpool strain of Aedes aegypti (L.) were used in this study. They were allowed to feed on D. immitis infected dogs with different microfilarial levels which were 1,650, 1,950, 9,000, 9,250, and 11,550 microfilariae per one ml of blood. Mosquitoes were forced to feed on solution (5% sucrose in 5% dog serum) in capillary tubes for 20 minutes at 7-34 days post-blood feeding. Solutions in capillary tubes then were examined and mosquitoes were dissected and examined for D. immitis larvae under a light microscope. Second stage larvae could be found in the abdomen and malpighian tubules of mosquitoes and third stage larvae can be found in the abdomen, malpighian tubules, thorax, and proboscis of mosquitoes with different levels of infection. No larvae were detected in the solution in capillary tubes of all experiments.

A survey of metacercariae in cyprinoid fish in Nakhon Ratchasima, northeast Thailand.

Metacercariae were recovered from freshwater fish taken from a stream in Lum Cha Muak, Nakhon Ratchasima Province, northeast Thailand during the year 2000. Seventy-nine cyprinoid fish comprising 3 species (52 Puntius leiacanthus, 22 Cyclocheilichthys armatus, and 5 Hampla dispar) were collected. The prevalence of infection with metacercariae was 51.9%. Only two genera of metacercariae were found: Haplochinae spp and Heterophyidae spp. Haplochinae metacercariae were found in all 3 species of fish, giving rates of infection of 95.5%, 20% and 1.9% for Puntius leiacanthus, Cyclocheilichthys armatus and Hampla dispar respectively. Heterophyidae metacercariae were found only in Puntius leiacanthus, whose infection rate was 30.77%. There were fish intected at the rate of 3.8% with unclassified metacercariae. Interestingly, no fish infected with Opisthorchis viverrini metacercariae were found, which is at odds with previous reports from Thailand in which a higher infection rate was given. This is the first report of fish infected with Haplorchinae spp in Thailand.

The formol-ether concentration technique for intestinal parasites: comparing 0.1 N sodium hydroxide with normal saline preparations.

The formol-ether method is a widely used technique for stool examination. We performed a comparative study of 0.1 N sodium hydroxide (NaOH) and normal saline preparation for the formol-ether technique in the detection of intestinal parasites. Of 30 parasite-containing stool samples, 22 (73%) were positive by 0.1 N NaOH and 18 (60%) were positive by normal saline. The detection rate of both preparations was not significantly different (p>0.05).

A survey of trematode cercariae in Bithynia goniomphalos in northeast Thailand.

A survey of trematode larvae in the fresh water snail, Bithynia goniomphalos in the main water reservoir of Huai Thalaeng district, Nakhon Ratchasima Province, Thailand, was conducted. The study site is in an area with a high prevalence of Opisthorchis viverrini infection. Malacological samplings were made during the year 2000 to study the prevalence and intensity of infection. Parasitological examinations of 527 live snails were performed at the Veterinary Parasitology Laboratory, Chulalongkorn University. Of the 527 snails, only 16 (3.04%) were found to be infected with cercariae. Of these 16 snails, 75% were infected with Amphistome cercariae, 6.25% with Armatae cercariae and 18.75% with Virgulate cercariae. Most infected snails (75%) had a density of infection of less than 100 cercariae/snail. No snail was infected with cercariae of Opisthorchis spp. This snail was, therefore, unlikely to be the intermediate host of Opisthorchis viverrini in the main water reservior of Huai Thalaeng district.