Filth Fly Management in Urban Environments - Urban Insect Pests: Sustainable Management Strategies - page 51

(Howard, 1911); however, it was not until
the studies carried out by Watt and Lindsay
(1948) and Lindsay et al. (1953) that there
was convincing evidence for the house fl y's
involvement. More than 30 viruses,
hundreds of bacteria, as well as a number of
fungi, protozoa and nematodes are
associated with Musca domestica alone
(Greenberg, 1971), but other fl ies are
certainly capable of transmitting diseases. A
partial list of the disease organisms trans-
mitted by house fl ies include Escherichia
coli (including O157:H7), Shigella spp.,
Salmonella spp., Helicobacter pylori ,
Yersinia pseudotuberculosis , and the organ-
isms responsible for typhoid fever, cholera,
summer diarrhoea, dysentery, tuberculosis,
anthrax, ophthalmia and parasitic worms
(West, 1951; Greenberg, 1971; Harwood and
James, 1979; Levine and Levine, 1991;
Grubel et al ., 1997; Iwasa et al ., 1999; Zurek
et al ., 2001; Geden, 2005; Butler et al ., 2010).

fl y larvae enter the human body accidentally,
usually when the host is unconscious or
cannot prevent fl y landing and oviposition,
or when fl y larvae move from an infested
wound into living tissue. A common type of
accidental myiasis occurs when food items
containing fl y eggs are consumed and the
larvae are able to eclose and develop inside
the human body (Sehgal et al ., 2002; Dogra
and Mahajan, 2010). Other common cases
involve female fl ies laying eggs in or around
body openings and the maggots migrating
into the body to fi nd a nutritional substrate
to sustain their development.

Causes of Fly Outbreaks

Natural disasters

After natural disasters, such as hurricanes,
tornadoes, fl oods, earthquakes, etc., it is
common for an immediate cessation of
sanitary services (PAHO, 1982). Disruption
of sanitary services causes an accumulation
of waste in the affected areas, either from
lack of collection of normal household and
business rubbish or from breakdown of the
sewage system. Depending on the severity
of the disaster, human corpses, as well as
that of many pets and other animals, may
also be exposed to oviposition by fi lth fl ies.
This abundance of breeding media, and the
availability of spoiled food items and other
organic matter that may serve as food for
adult and larval fl ies, combine to create
perfect conditions for fl y development. If
these disasters occur at a time of the year or
location with high temperatures, and
especially if heavy rains or fl ood add
necessary moisture, then the conditions are
prime for a rapid development of fl ies
leading to an explosive increase in the fl y
populations.
The aggravating factor in these situations
may be the fact that many people are
dislodged from their normal homes and
may be living in temporary quarters (tents,
broken down buildings, etc.) where they are
overly exposed to fl ies. Combined with
many other disruptions in normal life, the
annoyance produced by the presence of

Wounds and bacterial contamination

For as long as humans have been around,
the presence of adult fl ies and fl y maggots in
wounds has remained an issue. Because
adult fl ies will carry microorganisms on
their legs and other body parts, they can
easily infect wounds with bacteria that can
cause problems for the patient before the
wound is completely healed.
Flies can transmit bacteria, viruses and
other disease-causing organisms to wounds
via their faeces deposited during feeding or
regurgitation of material previously in-
gested (Thomas et al ., 1992; Kelly et al .,
1994; De Jesús et al ., 2004), or on their legs
and wings (Tan et al ., 1997). Flies are
responsible for the transmission of many
hospital infections of antibiotic-resistant
bacteria (Graczyk et al ., 2001).

Myiasis

Myiasis is the presence of non-parasitic fl y
larvae in the living tissue or organs of the
host, as opposed to having maggots in dead
tissue. In humans, myiasis can occur when