Philophthalmus is a genus of globally distributed parasitic eye flukes with some members of the genus found in disparate locales. In particular, Philophthalmus gralli, a zoonotic trematode, appears to be a relatively new introduction to the Americas, facilitated by spillover from the invasive snails Melanoides tuberculata (red-rimmed melania) and Tarebia granifera (quilted melania), which were introduced via the aquarium trade, and perhaps furthered by avian dispersal. Given that two known intermediate hosts of Philophthalmus flukes are actively expanding their range as a result of human activities, we hypothesize that this spread is also associated with the spread of Philophthalmus flukes. To address this, we systematically reviewed the literature and examined whether the global expansion of P. gralli flukes is associated with the spread of invasive snails M. tuberculata and T. granifera. Here, we show that (1) specimens of P. gralli are only found in intermediate snail hosts M. tuberculata or T. granifera, suggesting intermediate host specificity for these 2 species, and (2) specimens of P. gralli have rarely been found outside the ranges (native and introduced) of M. tuberculata or T. granifera. Given the importance of distribution information of parasites in the role of identifying parasite invasions, we also review the known distribution of all Philophthalmus species. Considering recent outbreaks in humans and wild and domestic animal species, the continued spread of Philophthalmus presents a potential threat to veterinary and public health and conservation.

https://bioone.org/journals/journal-of-parasitology/volume-107/issue-2/20-72/Spread-of-an-Avian-Eye-Fluke-Philophthalmus-gralli-through-Biological/10.1645/20-72.pdf

Spread of An Avian Eye Fluke, Philophthalmus gralli, Through Biological Invasion of An Intermediate Host.

Molecular detection of Giardia duodenalis by polymerase chain reaction (PCR) is difficult in faecal samples due to inhibitors that contaminate DNA preparations, or due to low cyst concentrations. In order to eliminate inhibitors, improve cyst recovery and molecular detection of G. duodenalis, different types of water, distillates (MDs), deionized (MDz), injection (MI) or Milli-Q® (MM) were used instead of formaldehyde (F) in the laboratory routine method (Ritchie). Cysts were isolated from faecal samples with low cyst concentrations (  2 cysts/field). Cyst recovery was improved using all water types (MDs, MDz, MI, MM) compared to formaldehyde. At all cyst concentrations, the use of MM consistently showed the greatest recovery of G. duodenalis cysts . DNA samples from recovered cysts were tested for the glutamate dehydrogenase (GDH) and β-giardin (βg) genes. The use of Milli-Q® water allowed to detect both genes in all cyst concentrations, including low. The method processed with the other types of water amplified these genes at high and medium cyst concentrations. GDH and βg genes were not detected when the sample was processed with formaldehyde. These experimental results were confirmed in clinical samples. The results suggest that Milli-Q® water provides the highest cyst recovery from stool samples and, correspondingly, the highest sensitivity for detecting G. duodenalis by microscopy or PCR for GDH and βg genes, even at low concentration of cysts.

Improvement in cyst recovery and molecular detection of Giardia duodenalis from stool samples.

Diarrheal diseases, including cholera, remain a major public health concern in developing countries like Nepal. This study investigated a diarrheal outbreak that affected over 1500 people in Gaidatar village of Rautahat district in central Nepal and sought to identify the source and causation of the disease. Stool samples were collected from individuals with acute diarrheal illness (n = 16) and healthy non-diarrheal children (n = 39), along with samples from local drinking water sources (n = 8) and their sewage system (n = 10). None of the individuals were sampled multiple times. Diarrheic stool and sewage samples were analysed for the presence of Vibrio cholerae, while coliforms were tested in drinking water samples following standard microbiological protocols. Enteric parasites were tested in both diarrheic and non-diarrheic stool samples. Vibrio cholerae O1 Ogawa serotype was isolated in 18.7% of the diarrheic stool and 20.0% of the sewage. Coliforms were found in all drinking water samples, with 87.5% testing positive for fecal coliform. Additionally, 43.6% of the stool samples (n = 55) had at least one of the intestinal parasites tested, primarily Giardia lamblia (21.8%). However, almost all parasites were found in non-diarrheal stool. Taken together, our results provide evidence that the diarrheal outbreak was associated with V. cholerae O1 Ogawa serotype, possibly transmitted through the drinking water sources contaminated with fecal matters from their sewage (drainage) system. These findings warrant regular surveillance of drinking water sources to help prevent future outbreaks.

Diarrheal disease outbreak in Gaidatar village of Rautahat District, Nepal

ABSTRACT Two cases of human philophthalmosis have been reported in Japan. Gravid flukes removed from the eyes of the patients were broken, but their morphological characteristics suggest that an unknown species of the genus Philophthalmus is involved as a pathogen for humans. The mitochondrial DNA barcode of the human eye fluke enabled us to discover its larval stage from the Japanese mud snail, Batillaria attramentaria. The discovered cercaria had previously been temporarily described as “Philophthalmid sp. I.” In this study, we examined the infection status of B. attramentaria with Philophthalmid sp. I found on a muddy seashore of the Seto Inland Sea, Japan, and the resulting metacercariae were experimentally administered to Japanese quails to develop them into the gravid adult stage. The complete specimens of the adult and larval stages allowed us to describe a new species. Based on morphological and molecular analyses, Philophthalmus hechingeri n. sp. is proposed for the human-infecting eye fluke in Japan. The natural definitive hosts of the new species are unknown. However, the habitat of B. attramentaria suggests that shorebirds (seagulls, sandpipers, and plovers) might be the possible candidates.

Philophthalmus hechingeri n. sp. (Digenea: Philophthalmidae), a Human-Infecting Eye Fluke from the Asian Mud Snail, Batillaria attramentaria

Philophthalmus gralli in domestic waterfowl: An environmental study in an urban area from Brazil.

Philophthalmid eyeflukes are cosmopolitan parasites of birds and occasionally of mammals, including humans. A gravid adult of Philophthalmus sp. was found from the bulbar conjunctiva of a 64-yr-old woman in Japan, who was diagnosed with acute conjunctivitis. The parasite was morphologically most similar to Philophthalmus hegeneri, but distinctive in lacking an esophagus and in having clearly lobed testes. The DNA sequence analysis of genes for nuclear 28S ribosomal RNA and mitochondrial cytochrome c oxidase subunit 1 supported the identification at generic level. The morphological and molecular analyses strongly suggest that the eyefluke from a human in Japan should be treated as an undescribed species of Philophthalmus. The occurrence of human philophthalmosis is very rare. As far as we know, a total of 11 human cases have been reported worldwide to date.

A Philophthalmid Eyefluke from a Human in Japan

The formalin-ether sedimentation (FES) method is considered as reliable method of fecal examination for the detection of parasites. In this study, we re-evaluated several aspects of FES such as (i) pretreatment of feces; (ii) filtration of fecal suspensions; (iii) test-tube material and (iv) substitution of ether by other organic solvents as to see an improvement in parasite egg recovery. The egg count was represented by the number of ova detected per 100 μg of sediment. Pre-treatment of feces with formalin (pH 7) increased egg detection rate remarkably compared with original FES method. Use of three layers of gauze dramatically reduced the sediment in the final product, and led to an increase in the number of ova detected. Use of polypropylene test tubes instead of glass test tubes also increased the number of egg detection. None of the organic solvents used to replace the ether produced better results. Based on these findings, we proposed a modified FES procedure. Further, we also compared the parasite positive rate and the number of ova recovered by using original FES and the modified FES procedures by examining 112 fecal samples collected from school children of parasite endemic area in Nepal. Feces collected from Nepal had many parasite ova, and these fecal samples barely displayed false-negative results even by method with low sensitivity. When the mean number of Hemenolepis nana, hookworm, T. trichiura, and A. lumbricoides ova recovered by original FES and the modified FES methods was compared, the values obtained by modified FES were superior (higher). This result suggested that the modified FES is effective and better for the recovery of parasite ova in areas of low-intensity parasitic infection.

/pdf/re-evaluation-of-the-formalin-ether-sedimentation-method-for-1futnk2xl2.pdf

Chitoshi Sato

Papers

A Philophthalmid Eyefluke from a Human in Japan

Re-evaluation of the formalin-ether sedimentation method for the improvement of parasite egg recovery efficiency.