10 Common Parasites In Humans
Life is more than what meets the eye in the sense that beyond our sight there is actually a haven out there, correction; not actually out there but within ourselves. We just became a haven for the breeding ground of micro-organisms (protozoan organisms), Helminths organisms (worms) and ectoparasites. We may be caught up in our world lost in it with the issues of finding appropriate life partners and employment problems but in fighting to be alive, we sustain life as well to the colony of unseen creatures we thought were just a figment of our imagination. Creatures which may come closer than our thinking when we realize they are capable to invade our bodies within from the flesh, our intestines and worst, to our brain. Our reality may never be what it seems when we gather our collective consciousness slowly consumed from the inside. These creatures may not literally eat us as a whole but the fact that we may be alive for years not knowing our state of infestation could be weird and distressing.
1. Malaria – Known to be caused by mosquito bites from a female Anopheles mosquito, this disease is caused by a eukaryotic protist of the genus Plasmodium. Out of 5 species of Plasmodium parasites infecting humans, Plasmodium falciparum is considered the most lethal. Malaria parasites could take 2 weeks, several months and in some cases years to propagate after infection finding station at the host’s liver until it multiplies and contaminates the red blood cells. Fevers and headaches start to manifest worsening to hallucinations, coma and finally death. An approximately 350-500 million malaria cases causing deaths of one to three million of mostly children with weak immune system happens each year. It is prevalent in tropical and subtropical regions, including some countries in the Americas, Asia and Africa.
2. Toxoplasmosis – Caused by the protozoan Toxoplasma gondii, the parasite infects all warm bloodied animals including humans. Cats were mainly the hosts/carrier and infection is usually generated by contact with raw meat and ingestion of cat’s faeces or contact with it. An estimated 1/3 of the world’s human population carry a Toxoplasma infection.
3. Amoebiasis – This infection is caused by the amoeba Entamoeba histolytica and shows as a gastrointestinal illness which could remain asymptomatic on an infected host for years and could only be determined after thorough medical examination. Considering our human tendency to seek medical attention in worst cases, amoebiasis could account for an estimated 70,000 deaths annually. Usually taken as a commensal (as in commensal relationship where an organism benefits while the other is unaffected) organism, E. Histolytica may pass on in most humans unnoticed (especially dependent upon the individual’s strong immune system) until the person’s death. However so, severe cases of amoebiasis could literally consume intestinal lining causing amoebic colitis or the liver leading to amoebic liver abscesses.
4. PAM/PAME – Primary Amoebic Meningoencephalitis is a disease caused by the Naegleria fowleri, a free living protist. Infection affects the central nervous system and commonly originates from insufflation of infected water where the parasite attaches to the olfactory nerve. The parasite then migrates to the cribiform plate to the olfactory bulbs of the forebrain. Infection will then progress to the mitral cell axons as the parasite multiplies and advance its path to the host’s cerebrum. Vomiting, delirium and seizures will signal the final phase of invasion and the victim falls into an irreversible coma. Death follows in 2 weeks as the result of respiratory failure when infection consumes the brain stem. Despite this disease’s rarity and lethality, fewer than 200 cases had been confirmed in 2004 advancing through the years. An in-hospital case fatality rate of 97% was recorded with just 3% of patient survival rate.
5. Tapeworms – There are over a thousand species of tapeworms and imagining 1 or 2 species might be living inside ourselves is kind of gory. Consider the irony of tending to a pet where out of your knowing we might be nurturing an unseen creature inside ourselves? Tapeworms live in the digestive tract of vertebrates which ultimately include humans. They are characterized by their heads (scolex) which they use to attach to walls of the intestines. When attached, the worms absorb the nutrients through the food taken by the host and grow its tail in the process. A beef tapeworm may grow to 40 feet and other species may reach as far as 100 feet. Raw meat like underprepared pork or beef, fish meat eaten raw and poor hygiene comes as the common source of infection.
6. Pinworms – Pinworms belong to the genus Enterobius and were actually a type of roundworm. Infection usually occurs to children after ingestion of worm’s eggs passed on from contaminated food, water and hands after handling a variety of objects while playing. Enterobius vermicularis is the common species affecting humans from the US, Europe and around the world. Pinworms have a limited 13 week lifespan but their infestation to a particular host may endure through reinfection thus extending another generation of these parasites to live inside hosts and be passed along.
7. Roundworms – It had been estimated that the total number of identified and unidentified roundworms might be more than 500,000. As of the present only 28,000 had been described out of which 16,000 were confirmed to be parasitic. Unlike flatworms, roundworms possess a digestive system with openings at both ends. Roundworms belong to the phylum Nematoda thus they are often referred as nematodes. Ascaris is the genus of common roundworms infecting humans referred to as “giant intestinal roundworm”. Ascariasis is a state of roundworm infection in humans mostly involving the Ascaris lumbricoides species. This affects mostly sub-tropical and tropical countries with poor sanitation. Male worms reach average of 10 inches and female worm about 13 inches. Identification of infection is usually rare and mostly identified through stool examination with presence of worm’s eggs. Symptoms of infection include bloody sputum, cough, worms in stools and vomiting some of it.
8. Liver Flukes – Commonly referred as trematodes, liver flukes are flatworms from the phylum Platyhelminthes and causes the infection called Fasciolosis. They usually establish a colony at the liver of most mammals including humans and prefer stations in bile ducts and gallbladder. Flukes basically feeds on blood and adults lay eggs passed through the intestine. Clonorchis sinensis is the common species among human infections and believed to be the 3rd most widespread worm parasite in the world affecting countries like Japan, China and the rest of Southeast Asia. These creatures were estimated to exist in 30,000,000 out of the world population.
9. Crab Louse – Infestation from crab louse in humans is referred to as Pediculosis. Considered as an ectoparasite, crab louse thrives outside the body of the human host, particularly the genitals (pubic louse) and areas of the body covered with hair including the eyelashes. These cute critters feed on blood and only exists in humans with related species infecting gorillas. Crab louse favour hairs of the genitals, abdomen, armpits and moustache in adults and eyelashes in children. Owing to the sensitive issue of genital infection by pubic lice going unreported, a rough estimate of 2 % affecting human population was estimated. Transmission of infection usually happens through sexual contact among humans and sharing of contaminated clothing, bedding, among parents and children. A regular bath following regular change of clothing and proper hygiene is instrumental in preventing and further infection.
10. Scabies – Another ectoparasite, the mite Sarcoptic scabiei is responsible for the infection referred as scabies or simply itch. This infection is considered contagious and characterized by skin rashes and redness with itching. In closer examination, the affected skin area is affected by the burrows of these microscopic parasites. The extent of infection would normally reach visual signs in 4-6 weeks of infestation while some individuals may have it for years without knowing it.
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