Echinostoma
Dongyou Liu in Handbook of Foodborne Diseases, 2018
The life cycle of echinostomes included three hosts: two intermediate hosts and a definitive host. The first intermediate host is usually aquatic snails; there are a range of animals that act as second intermediate host (snails, clams, fishes, amphibian, and reptiles), and the definitive host is usually fishes, reptiles, birds, and mammals.83 People can be contaminated by eating raw or undercooked freshwater bivalves, snails, or fish.2,66 The infected person releases eggs in the feces, and because of carrying the infection, he or she may become a reservoir of parasites. Thus, contamination of the environment and spread of the parasite may occur.47 In this case, poverty, malnutrition, poor sanitation, and lack of supervision,45 associated with ignorance, are factors that contribute to the occurrence of echinostomiasis in several countries and to an increase in the chances of echinostomiasis spreading among humans.47
The ecological context
Loretta A. Cormier, Pauline E. Jolly in The Primate Zoonoses, 2017
Two key cycles, sylvatic and urban, have been described for vector-borne infections, but a variety of intermediate stages may also come into play (e.g., Harper 2011; Higgs and Beaty 2005; Weaver 2005). The sylvatic or jungle cycle is enzootic with parasites circulating between mosquitoes and a single or multiple reservoir host species. In the strictest sense, the sylvatic cycles only involves infection of wild animals. However, humans may become accidental hosts of sylvatic parasites when they enter forest zones for a variety of activities, such as hunting game or extracting forest resources. Depending on the parasite, human beings may become dead-end hosts and transmit the infection no further, or if a competent host, they can potentially transfer the infection to other people.
Immunomodulation of Schistosomal-Induced Inflammation
Thomas F. Kresina in Immune Modulating Agents, 2020
All infectious diseases can be thought of as parasitic in nature in terms of host-organism interactions. There is an expanding literature regarding immune networks and infectious diseases. When they are considered in toto, it is apparent that idio-type and antiidiotypic molecules can play a dual role in the ecological relationships established between the host and invading parasite. Idiotypic and antiidiotypic molecules can be components of the host adaption to infection. In cases of symbiosis or chronic infection, immune network components can modify the host’s immune response and promote a state of tolerance to harmful autologous autoimmune responses. Thus, the host may suffer only mild abnormality or illness. In this case, adaptation to infection benefits both host and infective agent.
Nanoparticles for antiparasitic drug delivery
Published in Drug Delivery, 2019
Yuzhu Sun, Dongmei Chen, Yuanhu Pan, Wei Qu, Haihong Hao, Xu Wang, Zhenli Liu, Shuyu Xie
Parasites are a class of pathogens that are more harmful to human and livestock than bacteria, and they generally induce chronic diseases. Unlike most bacterial infectious diseases with rapid onset and obvious symptoms, many parasitic diseases are hardly diagnosed timely and thus bringing great economic losses to animal husbandry (Roberts et al., 1994). Moreover, many parasites are zoonotic pathogens that they can spread between humans and animals, thus posing huge risk to human health. For example, cystic echinococcosis (hydatid disease), a chronic helminthic disease, affects the human, domestic, and wild animals. This disease causes a reduction in the performance by 10% for the infected animals, through the decrease in the meat quality, milk production, and surviving of the offspring. Parasites always have distinct growth stages for surviving from one generation to the next. The parasites in different stages always produce distinct sensibility against the same antiparasitic drugs. Most parasites have life cycles containing intermediate organisms or vectors, which transport them from one to another host. Also, parasites can reside in host cells and establish reservoirs from which reinfection will occur, which often results in the long term and repeated infections. These properties lead to the considerable treatment difficulty for parasitic infections.
Tick transmission of toxoplasmosis
Published in Expert Review of Anti-infective Therapy, 2019
Toxoplasmosis is thought to be acquired by the transmission of T. gondii from the definitive to intermediate hosts, from intermediate to definitive hosts, as well as between similar definitive and between similar intermediate hosts. Intermediate hosts are all warm-blooded animals (mammals and birds), including humans. Definitive hosts are members of the family Felidae, for example, domestic cats [2]. Humans most commonly acquire toxoplasmosis by ingestion of T. gondii cysts in infected meat or by the ingestion of sporulated oocysts from water, soil or food contaminated indirectly from feline feces, or less frequently, directly from feline feces [2,9]. In the US, T. gondii is second only to Salmonella as a domestically acquired foodborne illness resulting in death [10]. Transmission by blood transfusion [11] and organ transplantation [12] has also been reported. Little is known about the relative importance of horizontal transmission of T. gondii between different host species or the epidemiologic impact of the different sources causing infection or disease.
Diagnostic and management strategies of ocular cysticercosis: current perspectives
Published in Expert Review of Ophthalmology, 2020
Cystercosis is a cestode infection that is an important problem in tropical medicine [1–3]. This is a form of Taenia species infection. The human cysticercosis is an accidental dead ended infection caused by pork tapeworm (Taenia solium). The disease is caused by larval cysts of the tapeworm. The two main ways that the patients can acquire this infection are ingestion of tapeworm eggs through a fecal-oral transmission or autoinfection. Basically, human is a definitive host for adult parasite and pig plays role as an intermediate hosts harboring parasitic larva. Accidentally, human might act as an intermediate host and result in cysticercosis. The heteroinfection due to intake of contaminated food or water with the parasitic eggs, external autoinfection by ingestion ova of the existing parasite or internal autoinfection by retrograde peristalsis that pushes proglottids bearing eggs from intestine directly to stomach are the three ways that a human might become an intermediate host and further develops cysticercosis. The disease is strongly related to poor hygiene and common in areas with poor background sanitation.