Pathophysiology and Gastrointestinal Impacts of Parasitic Helminths in Human Being

According to zoological sciences, parasitic worms are the most
successful invertebrate animals found as parasite (endoparasites...


Introduction
According to zoological sciences, parasitic worms are the most successful invertebrate animals found as parasite (endoparasites and exoparasites of other animals) with varied shape of elongate, threadlike, roundworms, or eelworms. Many of parasitic worm species are extremely successful parasites, their biological process and food availability is largely depend on the appropriate host of animals. Gastrointestinal parasitic worms are multicellular organisms, vermiform invertebrate animal species, almost microscopic, of which are endoparasites of animals (Pokharel, and Larsen [1]and Pokharel et al. [2]). In addition, intestinal parasites infect gastro-intestinal tract of humans such as helminthes and protozoan which live in intestinal wall (Loukopoulos et al. [3]).
Protozoans like Entoameba histolytica, and Giardia lamblia are single celled microscopic, able to multiply in humans, which contributes to their survival, cause serious infections (Patel and Khaldekar [4]) and transmit to another human through a fecaloral route (Magambo et al. [5]) and also helminthes are necked multicellular organisms, referred as intestinal worms even though not all helminthes reside in intestines (Markell et al. [6]). Similarly, in their adult form, helminthes cannot multiply in humans and they are able to survive in mammalian host for many years due to their ability to manipulate immune response (Bogitsh et al. [7]). have harmful effect on survival, appetite, growth, physical fitness, school attendance and cognitive performance (Green et al. 2011) and also poor sanitation, clean drinking water scarcity and poor personal hygiene practices may contribute to the rapid spread of intestinal parasite (Celiksoz et al. [8]). Furthermore, environmental factors also play a great role in the frequency of intestinal parasitic infection as hot and humid tropical climate favor increased parasite prevalence (Geiger et al. [9]). In addition, in developing countries, intestinal parasites are widely distributing due to low level of environmental sanitation, contaminated water and unaware of simple health promotion practices such as personal and food hygiene, altitudinal effect, urbanization, irrigation, and country resettlement (Endeshaw, et al. [10]). Utzinger, [11]). The epidemiology of intestinal parasitic infections shows that, parasites are found in every age group and in both sexes but, the incidence is high in some areas and in some age groups (Abu [12] and Judith et al. [13]). World Health Organization (WHO), large number of people around worldwide infected with some type of intestinal parasite, and amoebiasis, ascariasis, hookworm and trichiuriasis infections are among most common infections of top ten global health problems (CDC [14]) and more than 980 million people are infected by A. lumbricoides (Mengistu et al. [15]).
Lymphatic filariasis (LF) are endemic in 72 tropics and sub-tropics countries where about 1.4 billion people are at risk of infection and about 120 million people infected with one or more types of the lymphatic filariae (Rao [16]). The most highly distributed intestinal parasites includes Ascaris lumbricoides, Giardia lamblia, Necator americanus, Ancyclostoma duodenale, Trichuris trichiura, Enterobius vermicular, Wuchereria bancrofti and Brugia timori (Adem [17]) with varying prevalence in different areas. Therefore, collecting relevant information, organizing and brief scientific explanation on the above some example of human pathogenic gastrointestinal parasitic helminths invertebrate animals species is required.

Methods, Pathophysiology and gastrointestinal impacts of helminthes:
This article is mainly focus on the pathophysiology and gastrointestinal impacts of various helminthes including their symptoms, transmission, diagnosis, prevention and treatment of intestinal parasitic infections and also their economic impacts on human being. In addition, both primary and secondary data were collected using direct observation, books, articles and from key health personnel (i.e. doctors, health officers, nurses, and laboratory technician) and also the collected statistical data and information were analyzed and interpretation of quantitative data using table and figures, and the qualitative method represents by explanation.

Pathophysiology of intestinal parasitic worms:
In biological sciences, pathological information on the main causes and effects of the disease-causing pathogens of some intestinal parasites of human being and some other mammals are explained as follows.
Parasitic organisms can be endoparasites or ectoparasites living temporarily inside or on the body of other organisms as host (Adem [17]). The main routes of transmission of some helminthes, protozoa and microsporidia to humans is via the fecal-oral, direct contact with infected persons, zoonotic transmission, ingestion of contaminated food or water and so cause gastrointestinal infections (Xiao [18]) and also there are various ways of infecting and transmission of intestinal parasitic worms such as mosquito bites, ingesting organisms eggs, penetration of the body skin, when fecal matter get into the mouth via contaminated food or water, eating of raw meat containing encysted larvae of helminth species, swimming in contaminated water, oral and anal sex, nonsexual close contact like diaper changing (Capó [19]; CDC [14]). In addition, eating of raw meat containing encysted larvae of a species can lead to a disease with two phases called gastrointestinal phase (occur after ingestion of infected meat by humans) and systemic (parenteral) phase (occur when the larvae enter the lymphatic circulation then into the blood, skeletal muscles, myocardium, and brain which are high in oxygen content) (Capó,[19]).
Intestinal parasites are one of the most important causal agents of gastrointestinal disorders like diarrhea, dysentery, vomiting, lack of appetite, hematuria, abdominal distension, loss of weight, abdominal pain, nausea, and Iron deficiency anemia (Even and Stephenson, 2001; Wafa [20]) and also causes itching and scratching around perianal area, swelling of the lower limbs, pharyngeal irritation, cough, dyspepsia, etc. Therefore, spreading of intestinal parasitic infections can be controlled by family planning, protecting personal and environmental hygiene, health education and nutrition and also prevention strategies include use of proper sewage disposal methods, consumption of clean and treated safe drinking water and food, proper hygiene such as hand washing, cleaning fruits and vegetable before consumption (Evan et al. [21]).
According to the nature of gastrointestinal parasites, there are various methods of diagnosis and treatments suggested by physicians. These various diagnosis methods of intestinal parasitic infections can be done by morphological examination, host antibody detection, parasite antigen detection, parasite DNA detection, specific antigen detection in stool specimen, rapid diagnostic test, etc (Regnath et al. [22]) and also these infections are among the most widespread of all chronic human infections worldwide (Wafa [20]). There are different methods of treatment modalities for various intestinal parasites, antihelminthic medications include Albendazole, Mebendazole, Pyrantel Pamoate (Ashford, et al. [23], Gupta et al. [24]). The most common treatment for hookworm, pinworm, whipworm, roundworm and other worms are albendazole and/or mebendazole (Bethony,et al. [9]; Avinash and Mollie [25]) and Diethylcarbamazine is an effective microfilaricidal drug (Adinarayanan, et al. [26]).

Human gastrointestinal impacts of helminths (worms):
In biological sciences, human parasitic infections are the major medical problem all over the world, especially in developing countries where they cause more morbidity and mortality than other infectious diseases and are the primary cause of death. The two main groups of parasitic organisms are protozoans include plasmodium species and helminths metazoan organisms, include the cestodes, trematodes and nematodes (Gillian, et al. [27]).
Parasitic organisms are organisms that can found internal or external body surface of other organisms, can live in a variety of ecological settings and some infections have zoonotic importance as disease producing agents resulting in potentially serious infections (Dickson et al. [28]). There are many pathogenic gastrointestinal parasitic species cause diseases to human being and other animals with various shapes such as elongated, threadlike, roundworms, eelworms active invertebrate animals and helminths species have greatest medical importance (Gaurab [29]). Therefore, some of the   [32]). In this case, humans are definitive hosts for both Necator americanus and Ancylostoma duodenale and also primarily it infects dogs, but humans can be dead-end hosts that prevent the larvae from completing their life cycle (John et al. [33]).    Holland [46]). Therefore, protecting personal and environmental hygiene is the most important advisable prevention methods of Ascaris lumbricoides infection.     [55]; Johhn et al. [52]; Choi et al. [56]).
In addition to swelling of the lower limbs, Lymphatic filariasis also cause impairs the lymphatic system and can lead to the abnormal enlargement of body parts, causing pain, severe disability and social stigma. The major pathologic manifestations includes acute fever accompanied by tender swelling of the lymphatics male genitalia leads to dysfunction and swelling of the legs, arms, or breasts of human (Casiraghi et al. [55]; Choi et al. [56]).  Figure 7. Skin ulcer comes into contact with water the free-swimming larvae are released and this larvae then swim until they are eaten by a Cyclops or die (Peters and Gilles [57]). Therefore, it is very important treating drinking water to protect health of people which caused by drinking contaminated water.

Heartworms:
The heartworm (Dirofilaria immitis) is a type of parasitic filarial roundworm, also known as dog heartworm, a small tread-like worm that causes dirofilariasis, spread from host to host through the bites of mosquitoes and rarely infects humans (Amaral et al. [51] CDC [58]). There are four genus of mosquitoes that transmit dirofilariasis, such as Ades, Culex, Anopheles and Mansonia (CDC [58]). The main definitive host is the dog, but it can also infect cat, wolves, coyotes, jackals, foxes, and other animals such as ferrets, bears, seals, sea, lions and under rare circumstance humans (AHS [59]). However, opposing to their name, adult heartworms often reside in the pulmonary arterial system of the lung and the heart as indicated in figure 8 and also damage those vessels and tissues of infected host animals and causes a serious complications for the infected host if untreated eventually leading to death, most often as a result of secondary cognitive heart failure (Ettinger et al. [60]).  [61]). According to CDC [62], the tapeworms are parasites that live in the small intestines of many different animals species, including humans and its size is vary depending on the species, example, while Echinococcus multilocularis is less than 1 cm long, an adult Taenia saginata up to 10 metres long. Except for the head, a tapeworm's body is made up entirely of small segments, called proglottids, which break off from the end of the worm's tail and both intact proglottids and the eggs may be passed in the feces.
Of all the tapeworms in pets, Echinococcus spp. pose the greatest disease risk to people. Tapeworm infection in adult animals rarely causes illness, even with large numbers of worms, but the motile proglottids may cause irritation around the anus, causing the animal to chew or rub the area or "scoot" as indicated in figure 9. There are three main groups of tapeworms, each containing one or more species, that are a concern for most domestic animals and humans. Each group poses a different level of risk to people and may be spread between animals and people in a different way (CDC [62]). Intestinal tapeworm infections can be easily treated using oral dewormers such as praziquantel and also can be prevented in people using the two major components are preventing intestinal infection in pets and preventing human exposure to the parasite eggs and cysts (CDC [62]).