Helminths are multicellular parasitic organisms that can cause a range of infections [1]. They are encountered in the areas of the developed world with poor sanitation and socioeconomic conditions, and where various vectors that facilitate their transmission are present [1] [2] [3]. More than 2 billion people are affected worldwide. Helminthiasis, is an infection caused by several parasites which are classified as [1] [2] [3] [4] [5] [6] [7]:

• Intestinal roundworms - Ascaris lumbricoides (large intestinal roundworm), Ancylostoma duodenale and Necator americanus (hookworms), Strongyloides stercoralis (threadworm), Enterobius vermicularis (pinworm) and Trichuris trichura (whipworm) are perhaps the most prevalent helminthic organisms in the world, affecting almost 1 billion people in poorly developed parts of Latin America, Africa, and Asia (China and India) [1] [3] [4] [6]. Intestinal roundworms are all introduced into the human body after ingesting food or other products from soil contaminated with parasitic eggs, thus the term "soil-transmitted helminths" is frequently used [5] [6]. Some intestinal roundworms, however, can cause an infection by invading the human host through breaks in the skin when being in contact with contaminated soil, such as Necator americanus and Strongyloides stercoralis [1] [8]. The majority of patients are asymptomatic, but a range of clinical manifestations may be seen in severe infestation, particularly in immunocompromised children and adults [4] [6] [7]. Gastrointestinal complaints (nausea, vomiting, chronic abdominal pain, diarrhea, malnutrition, reduced appetite), pulmonary symptoms (cough, dyspnea), skin rashes and perianal pruritus are some of the most common symptoms, whereas dissemination of the parasite from the intestines into other organs might occur as well [1] [2] [3].
• Tissue roundworms - Filarial parasites (Loa loa, Wucheria bancrofti, Onchocerca volvulus, Brugia malayi), Trichinella spiralis (the causative agent of trichinellosis), Dracunculus medinensis (Guinea worm), Toxocara canis and T. cati (the causative agent of visceral larva migrans), and Ancylostoma braziliense (responsible for cutaneous larva migrans) are classified into this group of nematodes as they cause infections related to other tissues in the body [2] [3] [4]. Except for trichinellosis, widely known for its acquisition through contaminated meat products, and Dracunculiasis (ingestion of water contaminated with copepods that harbor parasitic eggs) various vectors are integral parts of tissue roundworm life cycle (Anopheles, Aedes, and Culex mosquitoes, as well as black flies) [1] [2] [3]. The sub-Saharan Africa is the principal area where tissue roundworm infections are diagnosed, while Latin America and Asia are also important sites [4]. When the infection is symptomatic, clinical features include lymphedema and elephantiasis (W. bancrofti and B. malayi), conjunctivitis, chorioretinitis and visual deficits (Loa loa and O. volvulus), whereas watery diarrhea, vomiting, abdominal pain, myalgia and weakness appearing peaking in intensity approx. 2-4 weeks after ingestion of contaminated meat are the hallmarks of T. spirallis, which may be life-threatening if complications (myocarditis, encephalitis) develop [6] [7] [8].
• Flukes - The most important helminth belonging in this group are Schistosoma spp. that cause human infection after their acquisition from water sources (through swimming, fishing or drinking) being contaminated by their eggs from snails, pivotal hosts for their life cycle [3]. The clinical course involves three distinct syndromes - the swimmer's itch (manifesting as a maculopapular rash 2-3 days after infection), acute schistosomiasis (also known as Katayama fever, distinguished by fever, hepatosplenomegaly and generalized lymphadenopathy), and chronic infection, in which gastrointestinal (diarrhea, vomiting, abdominal pain, nausea) and urinary (hematuria, obstruction, dysuria, etc.) symptoms are seen, depending on the species responsible for the infection [1] [2] [3]. Other notable flukes are those infecting the intestines (Fasciola hepatica, Fasciolopsis buski) and the liver (Clonorchis sinensis and Opisthorchis viverinni).

• Generalized Lymphadenopathy

  lymphadenopathy), and chronic infection, in which gastrointestinal (diarrhea, vomiting, abdominal pain, nausea) and urinary (hematuria, obstruction, dysuria, etc.) symptoms are seen, depending on the species responsible for the infection. [symptoma.com]

• Fatigue

  Recently, Aluna started to feel quite ill and began suffering from nausea, vomiting, and extreme fatigue. She has also become very confused. [study.com]

  Said parasites resides & stay in the gastrointestinal tracts, the liver & other organs Symptoms & Signs Symptoms includes abdominal pain, diarrhea, fever, fatigue, enlarged liver & spleen, cough, malabsorption, anemia bowel obstruction,dehydration, itchy [signssymptoms.org]

  Symptoms Symptoms of Helminthiasis are as follows: 1) Abdominal pain 2) Diarrhea 3) Fever 4) Fatigue 5) Pruritis ani 6) Gastrointestinal inflammation 7) Weight Loss 8) Eosinophilia 9) Dehydration 10) Anorexia 2. [slideshare.net]

  Anemia has also been associated with reduced stamina for physical labor, a decline in the ability to learn new information, and apathy, irritability, and fatigue.[3] A study of the effect of deworming and iron supplementation in 47 students from the Democratic [en.wikipedia.org]

• Abdominal Pain

  Gastrointestinal complaints (nausea, vomiting, chronic abdominal pain, diarrhea, malnutrition, reduced appetite), pulmonary symptoms (cough, dyspnea), skin rashes and perianal pruritus are some of the most common symptoms, whereas dissemination of the [symptoma.com]

  Recurrent urticaria, abdominal pain, peripheral eosinophilia, hyperimmunoglobulin E and small bowel abnormalities on roentgenograms prompted evaluation of a 36 year old man for intestinal parasitism. [ncbi.nlm.nih.gov]

  Common gastrointestinal complaints associated with helminth infection include abdominal pain, nausea, and diarrhea. [amboss.com]

  Disease Symptoms and Treatments: People with light soil-transmitted helminth infections usually have heavy infections can cause a range of health problems, including abdominal pain, diarrhoea, blood and protein loss, rectal prolapse, and physical and [omicsonline.org]

• Geophagia

  "Microbiological and health related perspectives of geophagia: an overview". African Journal of Biotechnology. 9 (36): 5784–91. a b c Crompton D. W. T.; Savioli L. (2007). Handbook of Helminthiasis for Public Health. [en.wikipedia.org]

  Young SL, Dave G, Farag TH, Said MA, Khatib MR, et al. (2007) Geophagia is not associated with Trichuris or hookworm transmission in Zanzibar, Tanzania. Trans R Soc Trop Med Hyg 101: 766–772. View Article Google Scholar 83. [doi.org]

• Abdominal Distension

  The commonest presenting features were abdominal distension (44 patients) and abdominal pain (38 patients). Thirty-three patients presented with vomiting, of whom 8 vomited worms. Twenty-five patients presented with peritonitis. [ncbi.nlm.nih.gov]

• Lactose Intolerance

  Worms compete directly with their hosts for nutrients, but the magnitude of this effect is likely minimal as the nutritional requirements of worms is relatively small.[17][18][19] In pigs and humans, Ascaris has been linked to lactose intolerance and [en.wikipedia.org]

• Epigastric Pain

  Examples include migration of A. lumbricoides through the mouth, occasional gastrointestinal symptoms (epigastric pain 0.3%, diarrhoea 0.3%, nausea 0.2%, vomiting 0.1%), central nervous system symptoms (headache 0.2%, dizziness 0.1%), and rare allergic [doi.org]

• Headache

  Reported adverse reactions include occasional vomiting (5%), dizziness (3%), headache (3%), and weakness (2%); all such reactions were mild and transient [37] – [39]. [doi.org]

  The usual mild side effects of praziquantel which generally do not require treatment are malaise, headache, dizziness, abdominal discomfort with or without nausea and/or vomiting, fever and urticarial. [intechopen.com]

As the majority of helminths can be diagnosed through appropriate microbiological methods, it is the physician's clinical suspicion during the assessment of the patient which plays an important role in the workup. Because helminthiasis encompasses a large number of parasitic organisms, however, a comprehensive clinical and laboratory workup is vital in narrowing the list of potential pathogens responsible for the infection. As most helminths are endemic for tropical parts of the world, a detailed patient history of recent travel to these areas, or if they resided in these parts of the world for a prolonged period of time [1] [3] [5] should be obtained. If patients did visit endemic regions, the physician should further assess if they consumed local products or were exposed to water sources that may have been contaminated [1] [3]. After performing a meticulous physical examination, laboratory workup should start with a complete blood count (CBC), which will reveal eosinophilia, one of the most important findings that point toward helminthiasis as the underlying cause of symptoms [7]. Current diagnostic strategies advise testing of feces, sputum, blood, urine, skin, and biopsies of the liver or muscle in rare cases, but the examination of feces is perhaps the main diagnostic method in the field of parasitology [1] [2] [3] [7] [8]. The majority of parasites are excreted in stool in their egg form, including all intestinal roundworms, the majority of flukes, and tapeworms as well (Taenia saginata, T. solium, Diphyllobothrium latum and Hymenolepsis nana) [1] [2] [3] [7]. On the other hand, detection of specific antibodies is available for several helminths, such as Strongyloides stercoralis, T. spiralis, lymphatic filariae (W. bancrofti and b. malayi), virtually all flukes, and T. canis and T. cati [1] [3].

• Dirofilaria Immitis

  Bourguinat C, Keller K, Bhan A, Peregrine AS, Geary TG, et al. (2011) Macrocyclic lactone resistance in Dirofilaria immitis. Vet Parasitol 181: 388–392. View Article Google Scholar 130. [doi.org]

• Tissue Nematode

  Nematodes. ii) Tapeworms: They are found in the intestine or larvae in the tissues. iii) Flukes: These are hermaphrodites with an exception of blood flukes. [slideshare.net]

1. Kasper DL, Fauci AS, Hauser SL, Longo DL, Jameson J, Loscalzo J. eds. Harrison's Principles of Internal Medicine, 19e. New York, NY: McGraw-Hill; 2016.
2. Mandell GL, Bennett JE, Dolin R. Mandel, Douglas and Bennett's Principles and Practice of Infectious Diseases. 8th ed. Philadelphia, Pennsylvania: Churchill Livingstone; 2015.
3. Murray PR, Rosenthal KS, Pfaller MA. Medical Microbiology. Seventh edition. Philadelphia: Elsevier/Saunders; 2013
4. Hotez PJ, Brindley PJ, Bethony JM, King CH, Pearce EJ, Jacobson J. Helminth infections: the great neglected tropical diseases. J Clin Invest. 2008;118(4):1311-1321.
5. Croker C, Reporter R, Redelings M, Mascola L. Strongyloidiasis-Related Deaths in the United States, 1991–2006. Am J Trop Med Hyg. 2010;83(2):422-426.
6. Brooker S, Clements AC, Bundy DA. Global epidemiology, ecology and control of soil-transmitted helminth infections. Advances in parasitology. 2006;62:221-261.
7. Nutman TB. Evaluation and differential diagnosis of marked, persistent eosinophilia. Immunol Allergy Clin North Am. 2007;27(3):529-549.
8. Nikolay B, Brooker SJ, Pullan RL. Sensitivity of diagnostic tests for human soil-transmitted helminth infections: a meta-analysis in the absence of a true gold standard. Int J Parasitol. 2014;44(11):765-774.