The First Acanthamoeba keratitis Case of Non-Contact Lens Wearer with HIV Infection in Thailand

Acanthamoeba keratitis (AK) is a rare sight-threatening corneal infection, often reporting from contact lens wearers. An asymptomatic human immunodeficiency virus (HIV)-infected Thai male without history of contact lens use complained foreign body sensation at his left eye during motorbike riding. He had neither specific keratitis symptoms nor common drugs responding, which contributed to delayed diagnosis. By corneal re-scraping, Acanthamoeba-like cysts were detected by calcofluor white staining and agar culture. The etiological agent obtained from the culture was molecularly confirmed by Acanthamoeba spp.-specific PCR, followed by DNA sequencing. The results from BLAST and phylogenetic analysis based on the DNA sequences, revealed that the pathogen was Acanthamoeba T4, the major genotype most frequently reported from clinical isolates. The infection was successfully treated with polyhexamethylene biguanide resulting in corneal scar. This appears the first reported AK case from a non-contact lens wearer with HIV infection in Thailand. Although AK is sporadic in developing countries, a role of free-living Acanthamoeba as an opportunistic pathogen should not be neglected. The report would increase awareness of AK, especially in the case presenting unspecific keratitis symptoms without clinical response to empirical antimicrobial therapy.

Forensically Important Blow Flies Chrysomya pinguis, C. villeneuvi, and Lucilia porphyrina (Diptera: Calliphoridae) in a Case of Human Remains in Thailand

This is the first study to report Chrysomya pinguis (Walker) and Lucilia porphyrina (Walker) (Diptera: Calliphoridae) as forensically important blow fly species from human cadavers in Thailand, in addition to Chrysomya villeneuvi (Patton) already known in Thailand. In 2016, a fully decomposed body of an unknown adult male was discovered in a high mountainous forest during winter in Chiang Mai province. The remains were infested heavily with thousands of blow fly larvae feeding simultaneously on them. Morphological identification of adults reared from the larvae, and molecular analysis based on sequencing of 1,247 bp partial mitochondrial cytochrome c oxidase subunit 1 gene (CO1) of the larvae and puparia, confirmed the above mentioned 3 species. The approving forensic fly evidence by molecular approach was described for the first time in Thailand. Moreover, neighbor-joining phylogenetic analysis of the CO1 was performed to compare the relatedness of the species, thereby affirming the accuracy of identification. As species of entomofauna varies among cases in different geographic and climatic circumstances, C. pinguis and L. porphyrina were added to the list of Thai forensic entomology caseworks, including colonizers of human remains in open, high mountainous areas during winter. Further research should focus on these 3 species, for which no developmental data are currently available.

OCCURENCE OF THERMOTOLERANT NAEGLERIA AND ACANTHAMOEBA IN SOME NATURAL WATER SOURCES IN CHIANG MAI

The free-living amoebae (FLA),Naegleria fowleri and Acanthamoeba spp. are ubiquitousin nature. Some thermotolerant FLA cause fatal human infections and the most importantsources of infection are in water. To determine the occurrence of thermotolerant FLA insome natural water sources around Chiang Mai, a total of 56 surface water and bottomsoil samples were collected from 28 water sources: water-loggedfi elds, ditches alongthe Chiang Mai-Lampang Superhighway, paddyfi elds, fi sh farms and large ponds. Thesediments of samples were cultured at 37 °C and thermotolerance was tested at 42 °C, withsubcultured amoebae.Naegleria and Acanthamoeba were morphologically differentiated,based on pseudopodia. Forty of the 56 samples (71.4%) yielded amoebae at 37 °C, and16 thermotolerant positive samples (28.6%) were further identifi ed at 42 °C. The thermotolerantpositive samples were recovered from all pH ranges of 5.0-8.5 and temperatureranges of 25-35 °C. Samples from the water-loggedfi elds gave the highest positive rate(75%), followed by those from paddyfi elds (50%), ditches (25%), large ponds (16.7%)andfi sh farms (15%). The number of thermotolerant positive samples obtained from watersamples (62.5%) was higher than that from soil samples (37.5%). Among 16 thermotolerantpositive samples, 6 (37.5%) were identifi ed as Naegleria spp., 3 (18.8%) as Acanthamoebaspp., 5 (31.3%) as a mix of both species, and 2 were unidentifi ed. High prevalenceof thermotolerant amoebae in the paddyfi elds and ditches indicated a health risk for localpeople.Chiang Mai Medical Journal 2009;48(3):117-124.