atholog P y & nt a M Meena et al., J Plant Pathol Microbiol 2019, 10:1 l i P c f r o o b DOI: 10.4172/2157-7471.1000472 l i Journal of a o l n o r g u y o J ISSN: 2157-7471 Plant Pathology & Microbiology Review ArticleArticle OpenOpen Access Access A Review on Infectious Pathogens and Mode of Transmission Meena M1*, Swapnil P2, Barupal T1 and Sharma K1 1Department of Botany, University College of Science, Mohanlal Sukhadia University, Udaipur, India 2International Centre for Genetic Engineering and Biotechnology, New Delhi, India Abstract The pathogen is a microorganism that is responsible for the infection. Specific pathogens cause specific infections with specific transmission cycles. Pathogens cause the diseases in humans as well as in animals. The life cycle of these pathogens includes growth phase, consolidation, and modification of structure, multiplication/ reproduction, spreading, and infection of a new host, which is called the development of the pathogen. The transmission of pathogens from present to future host follows a repeating cycle which can be simple or complex, where transmission occurs through multiple host/vectors which are known as a transmission cycle of disease. To prevent the infections, the transmission cycles of particular pathogen must be understood. In the present review, we focus on the pathogen development mechanisms in association with the host, symptoms and signs of infection of pathogens, and their transmission routes. Keywords: Microorganisms; Pathogen; Transmission; Infection; iv. Reproduce, by the use of host resources; and Vector; Foodborne v. Exit and expand to a new host. Introduction Symptoms and signs of infection caused by pathogens A pathogen (Greek word: pathos “suffering, passion” and genes Albeit, it is easily understood that why pathogenic microorganisms “producer of”) is a microorganism that causes disease in another would expand to reproduce in a host, but there is less lucid information organism (host) [1,2]. This pathogenic microorganism is known as about that why they would evolve to cause disease. One justification the infectious agent who may be the virus, bacteria, fungi, protozoa, may be that microorganisms elicited the pathological responses by prion or other micro-organisms. The study of pathogen and disease increasing the efficiency of their spread or proliferation/propagation is described under the field of pathology. There are a number of and therefore clearly have a discriminating advantage for the pathogen. substrates as well as pathways where the pathogens can invade a host, For example, virus-containing lesions found on genitalia caused by the principal pathways have diverse episodic time frameworks, but soil Herpes simplex infection, to expedite direct spread of the virus from an contamination has the fastest or most persistent potential for anchor infected host to an uninfected partner for the duration of sexual contact. aging a pathogen. There are many diseases which are caused by viral In addition, diarrheal infections are proficiently extended from patient pathogens consist of influenza, smallpox, chickenpox, mumps, measles, to caretaker. Moreover, the stimulation of the disease has no probable rubella and Ebola. Diseases caused by microorganisms in the human advantage for the pathogen [1,2]. There are several symptoms and signs body are distinguished as pathogenic diseases. that related to the infectious disease are directly emergence of the host’s Literature Review immune responses via swelling and redness at the site of infection as well as production of pus (mostly dead white blood cells), therefore Pathogens developed specific mechanisms in association the direct result of immune system cells attacking to exterminating the with host invading microorganisms. Fever, is also a preventive reaction, when the raise in body temperature can diminish the development of several The human body is a multifaceted and flourishing ecosystem microorganisms. which contains near about 1013 human cells and surrounds several natural defences adjacent to various frequent pathogens in the form Transmission of pathogens of the human immune system and through a number of “helpful” bacteria, protozoan, and fungal cells, which represent thousands Pathogenic microorganisms cause disease in humans, animals, of microbial species. These microbes found in the human body’s plants as well as in other species. The pathogenic transmission known the normal flora, are frequently limited to certain areas of comprises three steps: rescue from the host, travel and infection of the body, together with the skin, mouth, large intestine, and vagina. the new host. Pathogenic transmission occurs in numerous manners, Besides, humans are frequently infected with viruses, most of which frequently reliant on the organism’s ecology. For instance, respiratory occasionally, if ever, become symptomatic. Pathogens are commonly distinguished from the normal flora and do not require that the host be immuno-compromised or injured. The pathogens have developed *Corresponding author: Meena Meena, Department of Botany, University College eminently specialized mechanisms for passing biochemical barriers of Science, Mohanlal Sukhadia University, Udaipur, India, Tel: +91-8726699266; as well as cellular barriers and for eliciting peculiar responses from E-mail: [email protected] the host organism that contribute to the survival and multiplication Received December 07, 2018; Accepted January 21, 2019; Published January of the pathogen. Consecutively to survive and multiply in the host, a 25, 2019 conquering pathogen must be competent to following criteria: Citation: Meena M, Swapnil P, Barupal T, Sharma K (2019) A Review on Infectious i. Colonize the host; Pathogens and Mode of Transmission. J Plant Pathol Microbiol 10: 472. doi: 10.4172/2157-7471.1000472 Stumble on a nutritionally well-suited niche in the host body; ii. Copyright: © 2019 Meena M, et al. This is an open-access article distributed under iii. Avoid, subvert, or circumvent the host innate and adaptive the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and immune reactions; source are credited. J Plant Pathol Microbiol, an open access journal ISSN: 2157-7472 Volume 10 • Issue 1 • 1000472 Citation: Meena M, Swapnil P, Barupal T, Sharma K (2019) A Review on Infectious Pathogens and Mode of Transmission. J Plant Pathol Microbiol 10: 472. doi: 10.4172/2157-7471.1000472 Page 2 of 4 pathogens are mostly airborne, whereas digestive tracts pathogens are Transmission via direct contact arising in water or food [3]. Pathogenic agents can be spread from Indirect transmission, an infected host transmits a disease directly animal-to-animal or animal-to-human via different transmission to another host via direct contact. The pathogens that pass through ways. Generally, pathogen transmission may occur through two types this manner are extremely sensitive to the environment and cannot of contact, direct and indirect, in which there are various mechanisms be sustain at the outer surface of the host for any length of time. For are involved. Figure 1 shows the chain of infectious disease via various example, sexually transmitted diseases (STDs) are caused by the pathogenic infectious agents, the different mode of transmission pathogens which are transmitted through blood, semen, or saliva. of pathogens, types of susceptible host, portal of entry and exit, There are some pathogens which are responsible for STDs comprise and types of the reservoir. Tremonema palidum (syphilis), Neisseria gonorrhoea (gonorrhoea), Figure 1: Summary of infection of disease through several pathogenic infectious agents, different mode of transmission, types of susceptible host, portal of entry and exit, and types of reservoir. Figure 2: Showing various routes of faecal-oral transmission with faeces via directly or indirectly to someone’s mouth could potentially transmit the pathogen. J Plant Pathol Microbiol, an open access journal ISSN: 2157-7472 Volume 10 • Issue 1 • 1000472 Citation: Meena M, Swapnil P, Barupal T, Sharma K (2019) A Review on Infectious Pathogens and Mode of Transmission. J Plant Pathol Microbiol 10: 472. doi: 10.4172/2157-7471.1000472 Page 3 of 4 Vector Species Pathogen Disease Infections of direct contact Onchocerciasis Black fly Simulium spp. Onchocerca volvulus (river blindness) The pathogens are directly transmitted through contaminated Rickettsia typhi Murine typhus hands, clothes, domestic flies, or such other type of contaminated Flea Xenopsylla cheopis Yersinia pestis Plague substances. This type of infections affect the skin or eyes, and the Kissing pathogens are present on the skin or in the affected body parts or eyes. Triatoma spp. Trypanosoma cruzi Chagas disease bug The pathogen enters the body through the skin or mucous membranes Bartonella quintana Trench fever such as the eyes. This category showed several other diseases such Pediculus humanus Louse Borrelia recurrentis Relapsing fever as trachoma, conjunctivitis, yaws, and scabies. These infections are humanus Rickettsia prowazekii Typhus connected with deprived personal hygiene and are water-washed. Leptotrombidium spp. Orientia tsutsugamushi Scrub typhus Some of these infections also have animal hosts. Mite Liponyssoides (chigger) Rickettsia akari Rickettsialpox sanguineus Transmission via indirect contact Sand fly Phlebotomus spp. Leishmania spp. Leishmaniasis Indirect transmission