KARACHI: There are about 35 species of insects that swarm towards flesh and animal remains each Eid. A study suggests that some of these pests raise the risk of harmful diseases among humans as well.
Dr Farrah Zaidi’s research titled, ‘A preliminary survey of carrion breeding insects associated with the Eidul Azha festival in remote Pakistan’ looks into this threat. Zaidi, a University of Peshawar department of Zoology lecturer, worked with Professor Xue-xin Chen of the Institute of Insect Sciences at Zhejiang University, China on this project.
The study explores how the massive production of animal offal after the slaughter coupled with the excrement gathered before, provides rich breeding grounds for carrion insects. The second aspect of the research looks into how these insects can be used to investigate crimes forensically.
Practices such as roadside slaughtering and dumping offal and blood in drains, ditches and dumpsters create a waste management problem, said the paper. Even if the pre-slaughter conditions are hygienic, large-scale sacrifices inevitably lead to a period of poor sanitation and the inefficient disposal of waste materials and offal. The researchers looked into aspects that would prove their theory. This includes how insects are attracted to blood pools, meat, hides and skins, bones and offal. Real-time insect succession - the predictable sequence in which insects colonise a body - on goat offal was examined at different dump sites in Chah Syed Munawar Shah village in Dera Ismail Khan in 2009 when Eid fell on December 9 to 11.
The 35 insect species may vary slightly by differences in geographic location within the country, Dr Zaidi explained. They were collected from 14 sites, both indoor and outdoor. Refuse at dump sites attracts the most insect species, both by taxa and in numbers, followed by hides in courtyards, meat in kitchens and pools of blood in courtyards, she added.
These insects include flies, ants, moths, beetles, mites, wasps, bees and centipedes among others.
The most common however, are flies.
Most of these flies, referred to as ‘filth flies’ are likely to pick up harmful pathogens and drop them on food, spreading diseases as diarrhoea, dysentery, food poisoning, poliomyelitis, typhoid and tuberculosis. More than 55 diseases caused by flies have been identified in humans and animals, said Zaidi. Their larvae can cause myiasis - an infection caused when larva feeds on living tissue. The blowfly is the most abundant throughout Asia.
Though it warned of these health hazards, the basic purpose of the research was to explore ‘forensic entomology’.
This is the application of the study of insects and arthropods to criminal cases such as murder investigations.
For example, post-mortem interval (PMI) estimation, the method of putting together a timeline of incidents, allows investigators to reconstruct events and circumstances. This can be employed in both criminal cases and civil cases when the death is natural, accidental, or a suicidal. Monitoring insect activity has been observed to be the most effective approach to make these estimates. The study hopes to determine which insects are forensically useful to a region.
The method is already being used in China, European Union countries and America. “This technique can be extremely useful for Pakistan if applied in criminal cases given the incidence of terrorism in the country,” she claimed.
Apart from investigations, it can be used to check the nutritional content of food by looking into insect infestation and can be used to assess the quality of pulses, rice and flour.
Published in The Express Tribune, November 10th, 2011.
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