Middle East DVEP - Armed Forces Pest Management Board

principal plague vector. Pulex irritans, commonly termed the human flea, occurs mainlyin temperate countries among lower socioeconomic groups. This species is absent fromthe Arabian Peninsula. The northern rat flea, Nosopsyllus fasciatus, is involved only inthe sylvatic plague transmission cycle. This species is rare in arid areas of the ArabianPeninsula. It is much more common in northern areas of Syria, Iraq and Iran. It is alsowidely though focally distributed in Turkey, depending on host availability. AppendixA.4. lists the distribution of fleas in the Middle East.Adult fleas feed exclusively on blood and utilize blood protein for egg production.After feeding on a rodent, the female Oriental rat flea lays several (2 to 15) eggs. Severalhundred eggs may be laid during the entire life span. Oviposition most often occurs onthe hairs of the host, although the eggs drop off and hatch in the nest or its environs. Inlocally humid environments, such as rodent burrows, eggs may hatch in as little as 2days. Larvae live in the nest and feed on dried blood, dander, and a variety of organicmaterial; they grow rapidly when temperature exceeds 25°C and the relative humidity isgreater than 70%. The larval stages can be completed in as little as 14 days (at 30 to32°C), or as long as 200 days when temperatures drop below 15°C or when nutrition isinadequate. Mature larvae pupate in cocoons, loosely attached to nesting material. Adultemergence from pupae may occur in as little as 7 days or as long as a year and isstimulated by carbon dioxide or host activity near the cocoon. Adult fleas normally awaitthe approach of a host rather than actively search for one. They feed on humans whenpeople and rodents live close together, but man is not a preferred host. However, if ratpopulations decline suddenly due to disease or rat control programs, fleas readily switchto feeding on humans. The life span of adult X. cheopis is relatively short compared tothat of other fleas species.The life cycle of X. astia is very similar to that of the Oriental rat flea except it lives onboth wild and commensal rodents. Gerbils are the preferred hosts in rural areas. The lifecycle of the human flea, P. irritans, is also similar to that of the Oriental rat flea. Despiteits common name, P. irritans has a low to moderate preference for humans and is morelikely to feed on rats, mice, and gerbils, maintaining the enzootic plague cycle amongthese hosts. The human flea prefers swine hosts, which are rare in this region. Pulexirritans can live well over a year on these hosts. Domestic animals such as dogs alsoserve as hosts.The northern rat flea, N. fasciatus, has a life cycle similar to that of other fleas. However,it is tolerant of a broader range of temperatures than the Oriental rat flea. It rarely feedson humans. Adults of N. fasciatus and P. irritans can survive unfed for several months.Vector Surveillance and Suppression. The methods of flea surveillance depend uponthe species of flea, the host, the ecological situation, and the objective of theinvestigation. Fleas can be collected from hosts or their habitat. The relationship of hostdensity to flea density should be considered in assessing flea populations. It has beencommon practice for years to use a flea index (average number of fleas per host),especially in studies of rodent fleas. For X. cheopis, a flea index > 1.0 flea per host isconsidered high. The flea index has many limitations, since only adults are considered100