General Introduction

GENERAL INTRODUCTION Rodents pose a threaten towards crops in fields and stores. In addition, they may attack people and their domestic animals spreading many infectious diseases via their endo- and ectoparasites. The control of Norway rat (Rattus norvegicus Berk.), the most prevailing species lives close to man, depends mainly on rodenticides such as metal phosphides, fluoroacetamide, hypercalcemics and the worldwide commonly used coumarin-derived anticoagulants. Constituting over 40% of all mammal species, Rodents are the largest and most successful group of mammals worldwide. They have a high rate of reproduction and a good ability to adapt to a wide variety of habitats (Parshad 1999) Although rodents are often only associated with infrastructural damages, crop attacking and eating or spoiling of stored food and products, the veterinary and zoonotic risks of rodents are frequently underestimated. Wild rodents can be reservoirs and vectors of a number of agents that cause serious diseases for human and domestic animal; there are more than 20 transmissible diseases that are known to be directly transmitted by rodents to humans, by the assistance of bloodsucking parasites like fleas, ticks and mites (Khatoon et al. 2004). Wild rodents act as definitive and/or intermediate hosts of many parasites, which are common to domestic animals, and humans. Some rodent parasites are epidemiologically important as they are prevalent parasites of humans and their domestic animals. The eggs of parasites are passed out in rodent droppings in fields, grain stores and amongst foodstuffs in houses, and are responsible for disease spread (Khatoon et al. 2004). As rodents live in a close proximity with human and their animals and expose to the blood-sucking arthropods, the possibility for transmission of parasites increases. Controlling of rodents and their endo- and ectoparasites has been done mainly using anticoagulant rodenticides. The repeated use and application of such anticoagulant rodenticides for long periods may result in the rapid development of resistance to these compounds in wild rodent species. Resistance to anticoagulants can develop in a population after 5-10 years sustained use of anticoagulant rodenticides. No enough data exist on the baseline susceptibility of rodent populations in Egypt to anticoagulants or their changing patterns of susceptibility in areas of sustained use. Monitoring systems for rodent populations and changes to poisoning methods will assist Egypt rodent control groups in avoiding the resistance-induced control problems now seen outside Egypt. Sustained control of rodents is likely to be substantially dependent on toxicants, and anticoagulant poisons in particular, for the foreseeable future. 2 The aim of this work This study was carried out to determine what the major Norway rat parasites are, and to monitor its resistance to warfarin anticoagulant rodenticide at some governorates of Egypt. Therefore, the scope of the present work was to cover the following points: 1- To study the Norway rat species population structure at four different governorates. 2- To identify Norway rat helminthic parasites and to determine their incidence and distribution at four different governorates. 3- To identify Norway rat ectoparasites, and to determine their prevalence and general indices that is useful to understand the role of arthropod vectors as well as mammalian reservoirs in the maintenance of various diseases in the study areas. 4- To monitor the Norway rat resistance to warfarin (First generation anticoagulant rodenticide) at four different governorates by using the conventional method, non- choice feeding test. 5- To monitor the Norway rat resistance to anticoagulants rodenticides (warfarin) at four different governorates through VKORC1 analysis using Polymerase Chain Reaction (PCR) technique. 3 4 Part I: Endo and Ectoparasites of Rattus norvegicus INTRODUCTION Norway rat, Rattus norvegicus (Berk. 1769), is a cosmopolitan rodent species with a wide distribution in urban and suburban-rural habitats. It is commonly found living near sources of food and water, such as garbage and drainage ditches, streams or sewers. Because of its high ability to harbor many zoonotic agents, wild Norway rats play a significant role as definitive and/or intermediate hosts for vector-borne animal and human diseases (Easterbrook et al., 2007). Zoonotic disease or zoonosis are the diseases that can be transmitted from either wild or domesticated animals to humans. About 60% of all infectious disease agents affecting humans are zoonotic in origin and most of the zoonotic reservoir species are rodents (Taylor et al., 2001). Viral, bacterial and protozoan pathogens responsible for zoonotic diseases are excreted by rodent hosts or are transferred via the bite of a bloodsucking arthropod and then enter the human body via inhalation, swallowing or skin punctures (Ostfeld and Holt, 2004). The most famous zoonotic disease associated with rodent presence is probably the infection of rodent fleas with bubonic plague caused by Yersinia pestis bacterium, resulting in many millions of casualties worldwide. 5 Endoparasites of rodents play an important role in the zoonotic cycles of many diseases, such as, schistosomiasis and angiostrongyliosis. Parasites in rats, particularly helminthes, belong to the four major groups; Nematoda, Cestoda, Trematoda and Acanthocephala. Cestode and nematode parasites in rat have been reported from all parts of the world. Vampirolepis nana and Hymenolepis diminuta are commonly found in rats and mice and they are potentially transmissible (Zoonosis) to man. The occurrence of H. diminuta and V. nana in certain rodents is of interest since the possibility exists that rats and mice may serve as reservoir hosts and help in dissemination of these worms to domestic animals and man causing zoonosis (Jawdat and Mahmoud, 1980). Also, rodents are suitable for hospitality of some groups of arthropods that are known as ectoparasites. They are well - adapted for living on the external surface of rodents bodies (permanent or temporary). Rats are known to harbor four groups of arthropod ectoparasites: fleas, ticks, mites and lice (Ansari, 1953; Abu-Madi, et al., 2005). Ectoparasitic arthropods as vectors of zoonotic pathogens have an important role in causing diseases such as anaplasmosis, ehrlichiosis, rickettsiosis, plague, lyme borreliosis, viral encephalitis, tularemia, CCHF, zoonotic leishmaniasis, murine typhus, etc. They can also transmit disease to human by: feces, urine, saliva, milk and blood. 6 Among the ectoparasites infesting rats, the best known and most dangerous to man is the rat flea, Xenopsylla cheopis (Rothschild). This flea is the vector of Yersinia pestis, the causative agent of plague, and Rickettsia typhi, the causative agent of murine typhus. Rickettsial agents, such as Anaplasma, Bartonella, Coxiella, Ehrlichia, and Rickettsia, have been detected by molecular tools from Egyptian ectoparasites, such as lice, ﬂeas, and ticks (Reeves et al., 2006). 7 8 REVIEW OF LITERATURE Indo and ectoparasites associated with Rattus norvegicus Rodents (rats and mice) follow man wherever he goes carrying with them many serious zoonotic diseases (El Shazly et al., 1991). Historically, R. norvegicus has played a major role in diseases transmission. This fact is still important in today's world as it acts as a reservoir and transmits many serious diseases of man and animals like plague, hymenolepiasis, leishmaniasis, trichinosis, babesiosis and toxoplasmosis. (Louisiana, 2000). 1. A brief about Rattus norvegicus (Berkenhout, 1769) Rattus norvegicus is a cosmopolitan rat species that may has many common names like brown rat, Norway rat, sewer rat or burrowing rat. Its usual habitat is away from houses, in drains or in burrows. It is fleshier than R. rattus with broad head, blunt muzzle, small eyes, short ears which, when drawn forward, do not touch each other. Fur is rough, grey brown above and whitish grey on the abdomen. The tail is shorter than the length of the body and head combined. The faecal pellets are sausage shaped and usually occur in groups. It is a commensal rat and not a true domestic rat (Nowak, 1999). Thought to have originated in northern China, R. norvegicus has now spread to all continents and is the 9 dominant rat in Europe and much of North America. It is a common pest wherever humans live particularly in urban areas and degraded environments (Banks et al., 2003). Classification of Rattus norvegicus (according to Nowak, 1999) Kingdom: Animalia Phylum: Chordata Sabphylum: Vertebrata Class: Mammalia Linnaeus, 1758 Subclass: Eutheria Parker and Haswell, 1897 Infraclass: Eutheria Gill, 1872 Order: Rodentia Bowdich, 1821 Suborder: Myomorpha Brandt, 1855 Family: Muridae Illiger, 1815 Subfamily: Murinae Illiger, 1815 Genus : Rattus Fischer, 1803 Rattus norvegicus (Berkenhour, 1767) 2. Endoparasites of rats The ecology, in particularly the component community structure, of helminth parasites in small rodent population has been well documented in temperate regions of Europe (Abu- Madi et al., 1998). In contrast, and despite the wealth of information on species lists and taxonomy, there is little 01 comparable data for rodents living in tropics (Behnke et al., 2000). Rats and mice in Egypt are well-known to be the definitive hosts (reservoir hosts) of several helminthes (Arafa, 1968; Monib, 1980; Wissa, 1980). It has been known from the previous work that rats act as reservoir hosts for many parasitic helminthes

Load more