First report of human myiasis caused by Chrysomya megacephala and Chrysomya rufifacies (Diptera: Calliphoridae) in Thailand, and its implication in forensic entomology

We report a forensic entomology case associated with human myiasis in Chiang Mai Province, northern Thailand. The remains of a 53-yr-old-male were concurrently infested with third instars of the two blow fly species, Chrysomya megacephala (F.) and Chrysomya rufifacies (Macquart), near a severe tumor lesion presented on the lower right leg. The presence of third instars, approximately 5 d old, on the day following postmortem indicated that myiasis occurred before death. This is the first report of both fly species acting as a myiasis-producing agent in Thailand. Unsynchronized data between the age of fly larvae due to myiasis premortem and verified age/ condition of the corpse suggest a potential complication and error in the estimation of postmortem interval if other predisposition fly infestations are not considered.     

Ultramorphology of eggshell of flesh fly Liosarcophaga dux (Diptera: Sarcophagidae)

Eggs of Liosarcophaga dux (Thomson) (Diptera: Sarcophagidae) are elongated and slightly bean-shaped, measuring approximately 1.5 mm in length. Each is covered externally by an eggshell comprised of polygonal patterns. In this study, scanning and transmission electron microscopy were used to examine the eggshell of this species of flesh fly for the first time. No plastron region or median area was detected. Ultrathin sectioning of the eggshell revealed multiple layers in the shell that could be observed using transmission electron microscopy.     

Effects of eucalyptol on house fly (Diptera: Muscidae) and blow fly (Diptera: Calliphoridae)

The effects of eucalyptol were evaluated against the house fly, Musca domestica L., and blow fly, Chrysomya megacephala (F.). The bioassay of adults, using topical application, indicated that M. domestica males were more susceptible than females, with the LD50 being 118 and 177 microg/fly, respectively. A higher LD50 of C. megacephala was obtained; 197 microg/fly for males and 221 microg/fly for females. Living flies of both species yielded a shorter life span after being treated with eucalyptol. The bioassay of larvae, using the dipping method on the third instar, showed that M. domestica was more susceptible than C. megacephala, with their LC50 being 101 and 642 microg/microl, respectively. The emergence of adults, which had been treated with eucalyptol in larvae, decreased only in M. domestica. Having the volatile property, fumigation or impregnated paper test of eucalyptol or the efficacy of repellence or attractiveness merits further investigations to enhance bio-insecticidal efficacy.     

Hairy maggot of Chrysomya villeneuvi (Diptera: Calliphoridae), a fly species of forensic importance

We reported on the hairy maggot of Chrysomya villeneuvi Patton, collected from a human corpse in Thailand. Although the general morphology of the third instar closely resembled the more common hairy maggot blow fly, Chrysomya rufifacies (Macquart), the spines along the tubercles of each body segment could be used as a feature to distinguish between these species, with those of C. villeneuri bearing sharp-ended spines that encircle the entire tubercle. Not only has the resemblance of a hairy appearance between C. villeneuvi and C. rufifacies larvae been documented but also their similarity in predacious feeding behavior. The differentiation between these two species is necessary for post-mortem interval estimation in the corpse.     

Climate associated size and shape changes in Aedes aegypti (Diptera: Culicidae) populations from Thailand

In spite of the adult body size variability of Aedes aegypti (Linnaeus) and its likely association with life history and vectorial capacity, the causes of size variation itself have been only partially identified. In particular, possible important factors such as climatic variation have not received much attention.The objective of this 2-year study was to describe from field collections the relationship of Ae. aegypti metric properties with available climatic data. The study took place in a dengue hyperendemic area of Thailand. Fourth instar larvae (L₄) and pupae were collected from the same breeding places allowing the comparisons between seven successive collections, four in 2007 and three in 2008. Climatic data were relative humidity (RH) and temperature (T). They were considered for the periods covering either the pre-imaginal development or, assuming heritability of size, the previous generation. The pre-imaginal period was further subdivided into embryonic and larval phases of development. Size was estimated by traditional and geometric techniques, the latter based on 18 landmarks collected at the intersections of veins also allowing estimation of shape.The shape variation of the wing followed similar patterns as for size and was shown to be a passive allometric change. No significant correlation of size or shape could be disclosed with T. In contrast, significant correlation with RH was found during two periods of examination: (i) the period affecting the generation previous to the time of collection, suggesting possible selective mechanisms on genitors, and (ii) the one occurring during pre-imaginal development. The subdivision of the latter into embryonic and larval phases allowed to evidence a possible selecting effect on embryonic development. The selection would act through the resistance to water loss which is known to depend on the relative surface of the cuticle.In conclusion, our data highlight the importance of the emerged period of Ae. aegypti eggs as a critical time for the size of future adults, and point to the relative humidity as the likely selecting factor.     

Discontinuation of secondary prophylaxis against penicilliosis marneffei in AIDS patients after HAART

A retrospective cohort study was conducted to determine the relapse rate of penicilliosis marneffei after the discontinuation of itraconazole secondary prophylaxis in 33 HIV-infected patients who received HAART and had CD4 cell counts of 100 cells/mul or greater for at least 6 months. The observed incidence of relapse of penicilliosis marneffei was zero cases per 641 person-months (95% confidence interval 0-0.6 cases per person-month) after a median follow-up of 18 months (range 6-45).     

Lipid peroxidation,glutathione, vitamin E,and antioxidant enzymes in synovial fluid from patients with osteoarthritis

Aim: To compare levels of lipid peroxidation and antioxidants in synovial fluid from primary knee osteoarthritis (OA) patients with severe cartilage damage undergoing total knee replacement with those in the synovial fluid from injured knee joint patients with intact cartilage undergoing knee arthroscopy. Methods: Thirty‐two OA patients and 10 injured knee joint patients were recruited. Lipid peroxidation (thiobarbituric acid reactive substances [TBARs]), iron and glutathione (GSH) were measured using a colorimetric method. Vitamin E was measured with high‐performance liquid chromatography (HPLC). Activities of antioxidant enzymes (glutathione peroxidase [GPx], superoxide dismutase [SOD]) were analyzed with the use of a kinetic method. Results: TBARs, iron and GSH levels in synovial fluid were not significantly different between OA patients and injured knee joint patients. Antioxidant enzymes such as GPx and SOD activities also indicated no significant difference. Only vitamin E level was significantly lower in the synovial fluid of OA patients than in that of the injured knee joint patients. Conclusions: Oxidative stress may have a role in pathogenesis of knee osteoarthritis. Vitamin E supplementation may have a role in the management of patients.     

Socioeconomic determinants of infant growth: The Perspective Cohort Study of Thai Children

Aim: The present study is based on the Prospective Cohort Study of Thai Children (PCTC), and focuses on socioeconomic factors including maternal age, maternal education, living with parents, family size, family income, locality, and sex that affect the growth outcomes of infants at 1 year of age. Methods: Data was collected among 3679 pairs of mothers and infants in the PCTC cohort in rural and urban locations during 2001–2002. Data collection was performed by interviewing mothers in their 7th to 8th month of pregnancy using family profile questionnaires. The anthropometric measures including weight, length, and head circumference of the infants were later collected at 1 year of age at home. Results: The results show the effects of family socioeconomic status maternal education, living with parents, family size, family income, locality, and sex on their weight (R² = 14.2%, P < 0.001) and length (R² = 8.7%, P < 0.001) at 1 year of age. The findings suggest that maternal age, maternal education, living with parents, family size, family income, locality, and sex predict infant head circumference (R² = 16.8%, P < 0.001) at 1 year of age. Conclusion: Infants' growth, including weight, height, and head circumference, are affected by family socioeconomic status factors. It is recommended that the effect of maternal age on growth and development of children among those in the PCTC cohort is examined in the future.     

A pharmacokinetic study of paracetamol in Thai β-thalassemia/HbE patients

Background

Thalassemia may alter the pharmacokinetics of several drugs in thalassemic patients. Paracetamol is a commonly used analgesic and antipyretic drug which is extensively metabolized in the liver via glucuronidation. The aim of this study was to compare the pharmacokinetics of paracetamol (PCM) and its metabolites [paracetamol glucuronide (PCM-G), paracetamol sulfate (PCM-S), and paracetamol cysteine (PCM-C)] in 16 patients with 16 normal subjects.

Method

Following an overnight fast, a single dose of paracetamol (1,000 mg of Tylenol®) was given and blood samples were obtained at predose, 0.5, 1, 1.5, 2, 3, 4, 5, 7, and 9 h after dosing for determination of the plasma levels of PCM and its metabolites by high-performance liquid chromatography.

Results

There was no significant difference in maximum concentration of PCM between groups. However, a significantly shorter elimination half-life of PCM was observed in the thalassemic subjects (p<0.001). Total apparent clearance of PCM was significantly faster in thalassemic subjects (p<0.01) while the apparent volume of distribution of PCM did not change. The area under the concentration time curve (AUC_0->∞) of PCM-G and PCM-S increased in thalassemic subjects (p<0.05) whereas this parameter for PCM-C was slightly lower in the patients. The half-lives of PCM metabolites were significantly shorter (p<0.01) in thalassemic subjects.

Conclusion

The results indicate that the elimination of PCM and its metabolites in thalassemic subjects is faster than that in normal subjects. Our pharmacokinetic data provide additional evidence that plasma PCM-G is higher in thalassemic patients with hyperbilirubinemia, which could be a casual relationship in regulating the UDP-glucuronosyltransferase expression.