Occurrence of necrophagous flies of forensic importance in medico-legal cases in Tamil Nadu State, India

Background

The present study is based on the necrophagous fly samples collected from 24 medico-legal cases between the year 2011 and 2018 in Tamil Nadu State, India. The fly life stages were identified based on morphological features. Pre-autopsy condition of the human corpse colonized by necrophagous flies and indoor/outdoor occurrence of the flies were recorded.

Results

Chrysomya megacephala, Chrysomya rufifacies, Sarcophaga spp, and Musca domestica life stages were collected from the human corpses. Chrysomya megacephala was the most prevalent (70.8%) insects of forensic importance and found both in indoor and outdoor environments. Drowned and burnt human corpses were found to be only colonized by C. megacephala. Chrysomya rufifacies was found only in outdoor environments and Sarcophaga spp was found only in indoor environment. There was a fair agreement between the percentage occurrence of necrophagous flies in human corpse in the present study in Tamil Nadu State and percentage historical occurrence of necrophagous flies in human corpse in India.

Conclusions

Chrysomya megacephala was the predominant blowfly species found to colonize corpses in Tamil Nadu State, India. Chrysomya megacephala was the only blowfly species found to colonize both burnt and floating corpses and corpses located indoor and outdoor.

In vitro efficacy of amitraz, coumaphos, deltamethrin and lindane against engorged female Rhipicephalus (Boophilus) annulatus and Haemaphysalis bispinosa ticks

The present study compares the in vitro efficacy of four chemical acaricides, viz. amitraz, coumaphos, deltamethrin and lindane, against Rhipicephalus (Boophilus) annulatus and Haemaphysalis bispinosa ticks based on adult immersion tests. Amitraz, at 350 ppm, elicited 29.2 ± 4.17% mortality against R. (B.) annulatus, 100% inhibition of fecundity and absence of hatching of eggs laid by treated ticks. The same compound at 300 ppm caused 62.5 ± 12.5% mortality against H. bispinosa, 96.7% inhibition of fecundity and complete blocking of eclosion. The LC₅₀ value of amitraz against susceptible H. bispinosa was 181 ppm. Deltamethrin at 400 ppm, elicited 25.0 ± 4.81% adult R. (B.) annulatus mortality, 97.5% inhibition of fecundity and absence of egg hatching. Complete blocking of egg hatching was observed even at 30 ppm. However, deltamethrin (at 50 ppm) elicited 75.0 ± 10.76% mortality against H. bispinosa, 65.8% inhibition of fecundity and very low egg hatching (10%). The LC₅₀ for deltamethrin against susceptible H. bispinosa was 33.8 ppm. Coumaphos at 50 ppm, caused mortality of 70.8 ± 4.17% with R. (B.) annulatus whereas 100% mortality was observed against H. bispinosa. The LC₅₀ values of coumaphos against R. (B.) annulatus and H. bispinosa were 9 and 8.75 ppm, respectively. Complete inhibition (100%) of fecundity was observed even at 30 ppm against both parasites. Complete blocking of egg hatching was also observed even at 10 ppm of coumaphos. Lindane at 1000 ppm caused mortality of 87.5 ± 7.98% against R. (B.) annulatus and 83.3% mortality against H. bispinosa at 100 ppm. The LC₅₀ values of lindane against R. (B.) annulatus and H. bispinosa were 157 and 8.61 ppm, respectively. Complete inhibition of fecundity was observed with R. (B.) annulatus treated with lindane above 200 ppm and with H. bispinosa at a concentration above 50 ppm. Complete blocking of egg hatching was observed in R. (B.) annulatus, even at 100 ppm. Lindane caused 100% blocking of egg hatching at 1 ppm in the case of H. bispinosa.

Dirofilaria repens in scrotum of dogs

Out of 150 apparently healthy male dogs from Kerala, India examined, five revealed single worm in the scrotum. They were found protruding out from beneath the tunica vaginalis when it was incised during the castration operation. Genomic DNA isolated from these worms amplified D. repens specific 246 bp PCR products (KP050552, KP050553). Thickened and enlarged epididymis along with interductal fibrosis, congestion of veins and widening of the cavernous spaces of testes and epididymis were observed in the worm infected dogs. Semeniferous tubules were intact and showed various developmental stages of sperms. The infection resulted in less impact on spermatogenesis.The present communication forms the first report from India on the presence of D. repens in the peritoneal location, which is frequently observed in the subcutaneous locations.

Incidence of Onchocerca gibsoni in subcutaneous nodules of cross bred Jersey cows: case report

Onchocerca gibsoni subcutaneous nodules in four cross bred Jersey cows aged 5-6 years brought for post mortem with calcified and caseated skin nodules in the lateral flank region is reported. Examination and dissection of these nodules revealed that they were "worm nests" of Onchocerca sp. of filarid nematodes. The worm nests were carefully dissected and filarid worms were extracted out. Multiple numbers of worms were recovered from each nodule ranging from 15 to 20. Female worms were found inside the worm nests and were found to be filled with microfilariae. The nodules weighed 2-3 g. Based on the morphological features the worms were identified as O. gibsoni.

Histoarchitecture of ovary of Haemaphysalis bispinosa during engorgement period

The ovary of Haemaphysalis bispinosa was of panoistic type with asynchronous development of oocytes. The wall of the ovary was composed of a layer of epithelial cells to which the oocytes were attached by means of pedicel cells with elongated nucleus. The oocytes were classified into stages I to V based on morphologic characteristics like size and shape, presence / absence of germ vesicle, cytoplasmic appearance, presence or absence of yolk granules and presence of chorion. Day wise changes were in the form of occurrence of oogonia from partially fed upto day zero of engorgement, presence of all stages of oocytes on day one and two after engorgement and onset of degenerative changes in oocytes from day three onwards. Degeneration was complete on day eight with the appearance of polymorphism, vacuolation, cytoplasmic blebbing and autophagic activity in oocytes.

Acaricidal effects of fenvalerate and cypermethrin against Rhipicephalus (Boophilus) annulatus

The acaricidal effects of two most commonly used acaricides viz., fenvalerate and cypermethrin against Rhipicephalus (Boophilus) annulatus were studied using Adult Immersion Test (AIT). The LC50 values observed for fenvalerate and cypermethrin were 1570 ppm and 184 ppm respectively. The death of ticks was not an immediate process. Fenvalerate caused death only after 7 days while cypermethrin after 5 days of treatment. The eggs laid by treated ticks did not hatch at all concentrations tested.

Phylogenetic analysis of bovine Theileria spp. isolated in south India

The objective of the present study is to determine the phylogenetic position of the Theileria organisms in blood of cattle of southern India using molecular tools. Theileria annulata (Namakkal isolate, Tamil Nadu) and three Theileria field isolates (free of T. annulata) from Wayanad, Kerala (Wayanad 1, 2, 3) were used. The small subunit ribosomal RNA (SSU rRNA) and major piroplasm surface protein (MPSP) gene products were cloned, sequenced and the phylogenetic tree constructed. SSU rRNA gene of Wayanad 1 isolate (JQ706077) revealed maximum identity with Theileria velifera or Theileria cervi. The phylogenetic tree constructed based on SSU rRNA genes revealed that Wayanad 1 isolate belonged to a new type which share common ancestor with all the other theilerial species while Wayanad 2 and 3 isolates (JX294459, JX294460) were close to types A and C respectively. Based on MPSP gene sequences, Wayanad 2 and 3 (JQ706078, JX648208) isolates belonged to Type 1 and 3 (Chitose) respectively. When, the previously reported MPSP type 7 is also considered from the same study area, Theileria orientalis types 1, 3 and 7 are observed in south India. SSU rRNA sequence of South Indian T. annulata (JX294461) showed a maximum identity with Asian isolates while the Tams1 merozoite surface antigen (MSA) gene (JX648210) showed maximum identity with north Indian isolate.