Glossary

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Aberrant Host

An aberrant host is a host in which a parasite is unable to complete its normal development or the appropriate phase of its life cycle. Although infection may occur and partial development may take place, the parasite ultimately reaches a biological dead end. In aberrant hosts, the parasite is often found in atypical tissues or ... Read more

Abnormal Host

Abnormal Host An abnormal host is a broad term for a host that is not the parasite’s usual (typical) host. In parasitology, this generally includes two more precise categories: accidental hosts and aberrant hosts. Because “abnormal host” doesn’t specify whether the parasite can develop successfully, many references recommend using accidental or aberrant instead for clarity. ... Read more

Abopercular End

Abopercular End The abopercular end is the end of an egg that is opposite the operculum (the cap-like structure seen in some helminth eggs). When identifying parasite eggs under the microscope, recognizing which side is operculated helps orient the egg correctly. The abopercular end may show subtle shape differences or thickening in some species, which ... Read more

Acanthamoeba species

Acanthamoeba species (also referred to as Acanthamoeba spp.) Acanthamoeba species Details: Type: Free-living amoeba (single-celled organism) Category: Free-living protozoa Transmission Type: Waterborne, environmental exposure Primary Target Area: Eyes, skin, central nervous system Lifecycle Form: Exists in two forms — trophozoite (active feeding form) and cyst (environmentally resistant form) Incubation Period: Varies depending on type of ... Read more

Accidental Host

Accidental Host An accidental host is a host in which a parasite is not commonly found, but the host is still suitable for parasite development. The parasite may progress through expected stages, even though the host is not part of the typical life cycle. In some cases, the accidental host becomes a dead-end host because ... Read more

Acetabulum

Acetabulum An acetabulum is a muscular organ of attachment, commonly called a sucker. It is typically associated with helminths that must anchor firmly to host tissues. In trematodes (flukes), the acetabulum often refers to the ventral sucker used to maintain position against fluid flow or host movement. In cestodes (tapeworms), comparable sucker structures help the ... Read more

Active Transmission

Active Transmission Active transmission occurs when the parasite (or its vector) actively seeks out the host rather than relying on accidental contact. It can occur in two main ways: (1) an animate vector actively finds the host and delivers the parasite (e.g., tsetse flies transmitting African trypanosomiasis), or (2) an active parasite stage directly penetrates ... Read more

Adult Stage

Adult Stage The adult stage is the sexually mature phase of a parasite’s life cycle in which procreation occurs. In helminths, this stage typically produces eggs or larvae that continue the cycle. Adult parasites are often found in the definitive host (the host where sexual reproduction occurs). Depending on the parasite, adults may live in ... Read more

AIDS

AIDS AIDS (Acquired Immune Deficiency Syndrome) is a condition resulting from infection with HIV, where the immune system becomes severely weakened and less able to prevent or control infections. In parasitology, AIDS is especially important because reduced immune function increases susceptibility to opportunistic parasites and can lead to more severe disease, prolonged infection, or dissemination ... Read more

Alternate Host

Alternate Host An alternate host is one of two (or more) hosts that a parasite requires to complete its life cycle. The parasite alternates between hosts to reach different developmental stages. A common example is schistosomes, which alternate between snails (intermediate host) and humans (definitive host). Each host supports specific developmental steps that cannot occur ... Read more

Alternation of Generations

Alternation of Generations Alternation of generations describes a life cycle pattern in which different reproductive forms occur in successive generations—typically one sexual and one asexual. This is common in parasites where asexual multiplication increases numbers rapidly in one host, followed by sexual reproduction in another. Many trematodes show asexual amplification in the snail host and ... Read more

Amitotic Division

Amitotic Division Amitotic division is nuclear division by simple constriction without visible chromosome formation. The nucleus pinches into two, producing two nuclei that are typically described as equal. Unlike mitosis, amitotic division does not involve a spindle apparatus or clearly organized chromosome segregation. It is described in some protozoan contexts and is considered a simpler ... Read more

Ancylostoma duodenale (Hookworm)

Ancylostoma duodenale (commonly referred to as hookworm) Ancylostoma duodenale Details: Type:Helminth (parasitic roundworm) Category:Intestinal nematode (soil-transmitted helminth) Transmission Type:Skin penetration (soil-transmitted), oral ingestion (rare) Primary Target Area:Small intestine Lifecycle Form:Egg, rhabditiform larva, filariform larva (infective stage), adult worm (intestinal stage) Incubation Period:Symptoms may begin within weeks after exposure, depending on parasite load. Transmission: Ancylostoma duodenale ... Read more

Angiostrongylus cantonensis

Angiostrongylus cantonensis (commonly referred to as the rat lungworm) Angiostrongylus cantonensis Details: Type:Helminth (parasitic roundworm) Category:Nematodes (Roundworms) Transmission Type:Foodborne (ingestion of contaminated snails, slugs, or produce) Primary Target Area:Central nervous system (brain and spinal cord) Lifecycle Form:Larval stage (infective third-stage larvae), adult worm (in rats) Incubation Period:Symptoms typically develop 1 to 3 weeks after ingestion. ... Read more

Ascaris lumbricoides

Ascaris lumbricoides (also referred to as A. lumbricoides) Ascaris lumbricoides Details: Type: Helminth (parasitic roundworm) Category: Intestinal nematode Transmission Type: Fecal-oral (soil-transmitted) Primary Target Area: Small intestine (with temporary lung migration during lifecycle) Lifecycle Form: Egg (infective form), larval stage (migratory), adult worm (intestinal stage) Incubation Period: Symptoms related to lung migration may begin within ... Read more

Asexual Reproduction

Asexual Reproduction Asexual reproduction is reproduction without the formation and fusion of gametes (male and female). New individuals are produced through nonsexual processes such as binary fission, budding, or schizogony. In many parasites, asexual reproduction is a major strategy for rapid expansion within a host or vector, increasing the number of organisms available for transmission. ... Read more

Axostyle

Axostyle An axostyle is a rod-like internal structure that provides rigidity to the bodies of some flagellates, including Trichomonas species. It functions as a supportive “skeleton” that helps maintain cell shape and may contribute to movement or stability as the organism navigates through host environments. Why it matters: The axostyle is a useful structural feature ... Read more

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Babesia microti

Babesia microti (also referred to as B. microti) Babesia microti Details: Type: Protozoan parasite (single-celled organism) Category: Blood parasite (intraerythrocytic protozoa) Transmission Type: Vector-borne, bloodborne Primary Target Area: Red blood cells Lifecycle Form: Exists primarily as sporozoites (transmitted by ticks) and merozoites (infecting red blood cells) Incubation Period: Symptoms typically develop within 1 to 4 ... Read more

Balantidium coli

Balantidium coli (also referred to as B. coli or Balantioides coli) Balantidium coli Details: Type:Protozoan parasite (single-celled organism) Category:Intestinal protozoa Transmission Type:Fecal‑oral Primary Target Area:Large intestine (colon and cecum) Lifecycle Form:Exists in two forms — cyst (infective form) and trophozoite (active form inside the host) Incubation Period:Symptoms, when present, usually develop within a few days ... Read more

Blastocystis hominis

Blastocystis hominis (also known as Blastocystis spp.) Blastocystis hominis Details: Type:Protozoan parasite (single-celled organism) Category:Intestinal protozoa Transmission Type:Fecal-oral parasite (waterborne and foodborne) Primary Target Area:Large intestine Lifecycle Form:Exists in two forms — vacuolar form (active form) and cyst (infectious form) Incubation Period:Symptoms typically appear 1–2 weeks after exposure, though many individuals remain asymptomatic. Transmission:Blastocystis hominis ... Read more

Brugia malayi

Brugia malayi (also referred to as B. malayi) Brugia malayi Details: Type:Helminth (parasitic roundworm) Category:Filarial nematode (lymphatic parasite) Transmission Type:Vector-borne (mosquito transmission) Primary Target Area:Lymphatic system Lifecycle Form:Microfilariae (circulating larval stage), adult worm (lymphatic vessel stage) Incubation Period:Symptoms may take months to years to develop after infection. Transmission: Brugia malayi is transmitted through the bite ... Read more

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Capillaria philippinensis

Capillaria philippinensis (commonly associated with intestinal capillariasis) Capillaria philippinensis Details: Type:Helminth (parasitic roundworm) Category:Nematodes (Roundworms) Transmission Type:Foodborne (consumption of raw or undercooked freshwater fish) Primary Target Area:Small intestine Lifecycle Form:Egg, larval stage, adult worm (intestinal stage) Incubation Period:Symptoms may develop weeks after ingestion. Transmission: Capillaria philippinensis infection occurs when raw or undercooked freshwater fish containing ... Read more

Cimex lectularius (Bed Bugs)

Cimex lectularius (commonly referred to as bed bugs) Cimex lectularius Details: Type:Ectoparasite (blood-feeding insect) Category:Arthropods (Insects) Transmission Type:Environmental exposure (infested furniture, bedding, luggage) Primary Target Area:Skin (surface feeding) Lifecycle Form:Egg, nymph (five stages), adult bug Incubation Period:Bite reactions may appear within hours to several days after exposure. Transmission: Bed bugs spread through movement of infested ... Read more

Cleanse

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Clonorchis sinensis

Clonorchis sinensis (commonly referred to as the Chinese liver fluke) Clonorchis sinensis Details: Type:Helminth (parasitic flatworm) Category:Flukes (Trematodes) Transmission Type:Foodborne (consumption of raw or undercooked freshwater fish) Primary Target Area:Bile ducts within the liver Lifecycle Form:Metacercariae (infective encysted stage in fish), juvenile fluke, adult fluke (bile duct stage) Incubation Period:Symptoms may develop weeks to months ... Read more

Cryptosporidium Hominis

Cryptosporidium hominis (also known as C. hominis) Cryptosporidium hominis Details: Type:Protozoan parasite (single-celled organism) Category:Intestinal protozoa Transmission Type:Waterborne and foodborne parasite Primary Target Area:Small intestine Lifecycle Form:Exists in two forms — oocyst (infectious form) and sporozoite (active form) Incubation Period:Symptoms typically appear 2–10 days after exposure, though timing can vary. Transmission:Cryptosporidium hominis spreads through ingestion ... Read more

Cryptosporidium parvum

Cryptosporidium parvum (also known as C. parvum) Cryptosporidium parvum Details: Type:Protozoan parasite (single-celled organism) Category:Intestinal protozoa Transmission Type:Waterborne and foodborne parasite Primary Target Area:Small intestine Lifecycle Form:Exists in two forms — oocyst (infectious form) and sporozoite (active form) Incubation Period:Symptoms typically appear 1–2 weeks after exposure, though timing can vary. Transmission:Cryptosporidium spreads through ingestion of ... Read more

Cyclospora cayetanensis

Cyclospora cayetanensis (also known simply as Cyclospora) Cyclospora cayetanensis Details: Type:Protozoan parasite (single-celled organism) Category:Intestinal protozoa Transmission Type:Waterborne and foodborne parasite Primary Target Area:Small intestine Lifecycle Form:Exists in two forms — unsporulated oocyst (non-infectious when passed in stool) and sporulated oocyst (infectious form after environmental maturation) Incubation Period:Symptoms typically appear about 1 week after exposure, ... Read more

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Demodex brevis

Demodex brevis (commonly referred to as the sebaceous gland mite) Demodex brevis Details: Type:Ectoparasite (microscopic mite) Category:Arthropods (Arachnids) Transmission Type:Direct skin contact Primary Target Area:Sebaceous (oil) glands and hair follicles Lifecycle Form:Egg, larva, nymph, adult mite (resides deeper in sebaceous glands) Incubation Period:Symptoms, when present, may develop gradually over weeks. Transmission: Demodex brevis spreads primarily ... Read more

Demodex folliculorum

Demodex folliculorum (commonly referred to as the facial hair follicle mite) Demodex folliculorum Details: Type:Ectoparasite (microscopic mite) Category:Arthropods (Arachnids) Transmission Type:Direct skin contact Primary Target Area:Hair follicles (especially face, eyelashes, eyebrows) Lifecycle Form:Egg, larva, nymph, adult mite (lives within hair follicles) Incubation Period:Symptoms, when present, may develop gradually over weeks. Transmission: Demodex folliculorum is commonly ... Read more

Dientamoeba fragilis

Dientamoeba fragilis (also referred to as D. fragilis) Dientamoeba fragilis Details: Type:Protozoan parasite (single-celled organism) Category:Intestinal protozoa Transmission Type:Waterborne and foodborne parasite Primary Target Area:Large intestine Lifecycle Form:Exists mainly as a trophozoite (active form) inside the intestines; a cyst form may exist, but is not fully established. Incubation Period:Symptoms, when present, typically develop within 1–3 ... Read more

Diphyllobothrium latum (Fish Tapeworm)

Diphyllobothrium latum (commonly referred to as the fish tapeworm) Diphyllobothrium latum Details: Type:Helminth (parasitic tapeworm) Category:Intestinal cestode Transmission Type:Foodborne (consumption of raw or undercooked freshwater fish) Primary Target Area:Small intestine Lifecycle Form:Plerocercoid larva (infective stage in fish), adult tapeworm (intestinal stage in humans) Incubation Period:Adult worms typically develop within 3 to 6 weeks after ingestion ... Read more

Dipylidium caninum

Dipylidium caninum (commonly referred to as the flea tapeworm) Dipylidium caninum Details: Type:Helminth (parasitic tapeworm) Category:Intestinal cestode (zoonotic) Transmission Type:Ingestion of infected fleas (zoonotic) Primary Target Area:Small intestine Lifecycle Form:Egg packets, cysticercoid larva (infective stage in fleas), adult tapeworm (intestinal stage) Incubation Period:Adult worms typically develop within 2 to 3 weeks after ingestion of an ... Read more

Dracunculus medinensis

Dracunculus medinensis (commonly referred to as Guinea worm) Dracunculus medinensis Details: Type:Helminth (parasitic roundworm) Category:Tissue nematode Transmission Type:Waterborne (ingestion of contaminated water) Primary Target Area:Subcutaneous tissue (usually lower limbs) Lifecycle Form:Larvae (infective stage inside water fleas), adult worm (subcutaneous tissue stage) Incubation Period:Symptoms typically appear about 10 to 14 months after ingestion of contaminated water. ... Read more

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Echinococcus granulosus

Echinococcus granulosus (commonly associated with hydatid disease) Echinococcus granulosus Details: Type:Helminth (parasitic tapeworm) Category:Tissue cestode (zoonotic tapeworm) Transmission Type:Fecal-oral (zoonotic, dog-associated) Primary Target Area:Liver (most common), lungs, other organs Lifecycle Form:Egg (infective stage), hydatid cyst (larval stage in humans), adult worm (intestinal stage in dogs) Incubation Period:Symptoms may develop months to years after ingestion of ... Read more

Echinococcus multilocularis

Echinococcus multilocularis (commonly associated with alveolar echinococcosis) Echinococcus multilocularis Details: Type:Helminth (parasitic tapeworm) Category:Tissue cestode (zoonotic tapeworm) Transmission Type:Fecal-oral (wild canid-associated) Primary Target Area:Liver (primarily), with possible spread to lungs or other organs Lifecycle Form:Egg (infective stage), alveolar cyst (larval stage in humans), adult worm (intestinal stage in foxes and other canids) Incubation Period:Symptoms may ... Read more

Entamoeba histolytica

Entamoeba histolytica (also known as E. histolytica) Entamoeba histolytica Details: Type:Protozoan parasite (single-celled organism) Category:Intestinal protozoa Transmission Type:Fecal-oral parasite (waterborne and foodborne) Primary Target Area:Large intestine Lifecycle Form:Exists in two forms — trophozoite (active form) and cyst (infectious form) Incubation Period:Symptoms typically appear 2–4 weeks after exposure, though timing can vary. Transmission:Entamoeba histolytica spreads through ... Read more

Enterobius vermicularis (pinworm)

Enterobius vermicularis (commonly referred to as pinworm or threadworm) Enterobius vermicularis Details: Type: Helminth (parasitic roundworm) Category: Intestinal nematode Transmission Type: Fecal-oral, person-to-person Primary Target Area: Large intestine (colon and rectum) Lifecycle Form: Egg (infective form), larval stage, adult worm (intestinal stage) Incubation Period: Symptoms typically develop 2 to 6 weeks after ingestion of infective ... Read more

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Fasciola hepatica (Liver Fluke)

Fasciola hepatica (commonly referred to as the liver fluke) Fasciola hepatica Details: Type:Helminth (parasitic flatworm) Category:Flukes (Trematodes) Transmission Type:Foodborne / Waterborne (ingestion of contaminated aquatic plants or water) Primary Target Area:Liver and bile ducts Lifecycle Form:Metacercariae (infective encysted stage on aquatic vegetation), juvenile fluke (migratory stage), adult fluke (bile duct stage) Incubation Period:Symptoms may develop ... Read more

Fasciolopsis buski

Fasciolopsis buski (commonly referred to as the giant intestinal fluke) Fasciolopsis buski Details: Type:Helminth (parasitic flatworm) Category:Flukes (Trematodes) Transmission Type:Foodborne (ingestion of contaminated aquatic plants) Primary Target Area:Small intestine Lifecycle Form:Metacercariae (infective encysted stage on aquatic vegetation), juvenile fluke, adult fluke (intestinal stage) Incubation Period:Symptoms may develop weeks to months after ingestion. Transmission: Fasciolopsis buski ... Read more

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Giardia lamblia

Giardia lamblia (also known as Giardia intestinalis or Giardia duodenalis) Giardia lamblia Details: Type:Protozoan parasite (single-celled organism) Category:Intestinal protozoa Transmission Type:Waterborne and foodborne parasite Primary Target Area:Small intestine Lifecycle Form:Exists in two forms — trophozoite (active form) and cyst (infectious form) Incubation Period:Symptoms typically appear 1–2 weeks after exposure, though timing can vary. Transmission:Giardia spreads ... Read more

Gnathostoma spinigerum

Gnathostoma spinigerum (commonly associated with gnathostomiasis) Gnathostoma spinigerum Details: Type:Helminth (parasitic roundworm) Category:Nematodes (Roundworms) Transmission Type:Foodborne (consumption of raw or undercooked freshwater animals) Primary Target Area:Subcutaneous tissues (may migrate to other organs) Lifecycle Form:Third-stage larva (infective stage in humans), adult worm (in animal hosts) Incubation Period:Symptoms may develop days to weeks after ingestion, though migration ... Read more

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Hymenolepis nana (Dwarf Tapeworm)

Hymenolepis nana (commonly referred to as the dwarf tapeworm) Hymenolepis nana Details: Type:Helminth (parasitic tapeworm) Category:Intestinal cestode Transmission Type:Fecal-oral (direct egg ingestion), autoinfection possible Primary Target Area:Small intestine Lifecycle Form:Egg (infective stage), cysticercoid larva (intestinal stage), adult tapeworm Incubation Period:Adult worms typically develop within 2 to 4 weeks after ingestion of infective eggs. Transmission: Hymenolepis ... Read more

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Isospora Belli

Isospora belli (also referred to as Cystoisospora belli) Isospora Belli Details: Type:Protozoan parasite (single-celled organism) Category:Intestinal protozoa Transmission Type:Fecal‑oral Primary Target Area:Small intestine Lifecycle Form:Exists in two forms — oocyst (infective form) and sporozoite/trophozoite (active form inside the host) Incubation Period:Symptoms typically appear 1–2 weeks after exposure, though timing can vary. Transmission:Isospora belli spreads when ... Read more

Ixodes species (Ticks)

Ixodes species (commonly referred to as hard ticks or deer ticks) Ixodes Species Details: Type:Ectoparasite (blood-feeding arachnid) Category:Arthropods (Arachnids) Transmission Type:Skin attachment and blood feeding Primary Target Area:Skin (attachment site) Lifecycle Form:Egg, larva, nymph, adult tick Incubation Period:Local irritation may occur within hours; symptoms of tick-borne illnesses may develop days to weeks after a bite. ... Read more

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Leishmania donovani

Leishmania donovani (also referred to as L. donovani) Leishmania donovani Details: Type: Protozoan parasite (single-celled organism) Category: Intracellular protozoa (hemoflagellate parasite) Transmission Type: Vector-borne (sandfly transmission) Primary Target Area: Reticuloendothelial system (liver, spleen, bone marrow) Lifecycle Form: Exists in two main forms — promastigote (infective form transmitted by sandflies) and amastigote (intracellular form within human ... Read more

Leishmania major

Leishmania major (also referred to as L. major) Leishmania major Details: Type: Protozoan parasite (single-celled organism) Category: Intracellular protozoa (hemoflagellate parasite) Transmission Type: Vector-borne (sandfly transmission) Primary Target Area: Skin tissue Lifecycle Form: Exists in two main forms — promastigote (infective form transmitted by sandflies) and amastigote (intracellular form within human immune cells) Incubation Period: ... Read more

Loa loa

Loa loa (commonly referred to as the African eye worm) Loa loa Details: Type:Helminth (parasitic roundworm) Category:Filarial nematode (tissue-dwelling worm) Transmission Type:Vector-borne (deer fly transmission) Primary Target Area:Subcutaneous tissue (beneath the skin), eyes Lifecycle Form:Microfilariae (circulating larval stage), adult worm (subcutaneous tissue stage) Incubation Period:Symptoms may develop months to years after infection. Transmission: Loa loa ... Read more

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Microsporidia

Microsporidia Details: Type:Obligate intracellular, spore-forming parasites Category:Intestinal and systemic protozoa-like/fungal parasites Transmission Type:Fecal‑oral Primary Target Area:Primarily the small intestine, but it can affect multiple organs, such as the eyes, muscles, and respiratory tract Lifecycle Form:Exists in two forms — environmentally resistant spores (infective form) and intracellular replicative forms (meronts/trophozoites) Incubation Period:Symptoms usually appear within a ... Read more

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Naegleria fowleri

Naegleria fowleri (often referred to as the “brain-eating amoeba”) Naegleria fowleri Details: Type:Free-living amoeba (single-celled organism) Category:Free-living protozoa Transmission Type:Waterborne (nasal exposure) Primary Target Area:Brain and central nervous system Lifecycle Form:Exists in three forms — trophozoite (active feeding form), flagellate (temporary motile form), and cyst (environmentally resistant form) Incubation Period:Symptoms typically begin 1 to 12 ... Read more

Necator americanus (Hookworm)

Necator americanus (commonly referred to as hookworm) Necator americanus Details: Type:Helminth (parasitic roundworm) Category:Intestinal nematode (soil-transmitted helminth) Transmission Type:Skin penetration (soil-transmitted) Primary Target Area:Small intestine Lifecycle Form:Egg, rhabditiform larva, filariform larva (infective stage), adult worm (intestinal stage) Incubation Period:Symptoms may begin within several weeks after exposure, depending on parasite load. Transmission: Necator americanus infects humans ... Read more

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Onchocerca volvulus

Onchocerca volvulus (commonly referred to as the river blindness parasite) Onchocerca volvulus Details: Type:Helminth (parasitic roundworm) Category:Filarial nematode (tissue-dwelling parasite) Transmission Type:Vector-borne (blackfly transmission) Primary Target Area:Skin and eyes Lifecycle Form:Microfilariae (larval stage in skin and eyes), adult worm (subcutaneous nodules) Incubation Period:Symptoms may take months to years to develop after infection. Transmission: Onchocerca volvulus ... Read more

Opisthorchis viverrini

Opisthorchis viverrini (commonly referred to as the Southeast Asian liver fluke) Opisthorchis viverrini Details: Type:Helminth (parasitic flatworm) Category:Flukes (Trematodes) Transmission Type:Foodborne (consumption of raw or undercooked freshwater fish) Primary Target Area:Bile ducts within the liver Lifecycle Form:Metacercariae (infective encysted stage in fish), juvenile fluke, adult fluke (bile duct stage) Incubation Period:Symptoms may develop weeks to ... Read more

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Paragonimus westermani

Paragonimus westermani (commonly referred to as the lung fluke) Paragonimus westermani Details: Type:Helminth (parasitic flatworm) Category:Flukes (Trematodes) Transmission Type:Foodborne (consumption of raw or undercooked crustaceans) Primary Target Area:Lungs (primarily), occasionally brain or other tissues Lifecycle Form:Metacercariae (infective encysted stage in crustaceans), juvenile fluke (migratory stage), adult fluke (lung stage) Incubation Period:Symptoms may develop weeks to ... Read more

Parasite

Parastrongylus Species

Parastrongylus species (commonly associated with rat lungworm infection; often classified under Angiostrongylus) Parastrongylus Species Details: Type:Helminth (parasitic roundworm) Category:Nematodes (Roundworms) Transmission Type:Foodborne (ingestion of contaminated snails, slugs, or produce) Primary Target Area:Central nervous system (in humans) Lifecycle Form:Third-stage larvae (infective stage), adult worms (in definitive animal hosts such as rats) Incubation Period:Symptoms typically develop 1 ... Read more

Pediculus humanus capitis (Head Lice)

Pediculus humanus capitis (commonly referred to as head lice) Pediculus humanus capitis Details: Type:Ectoparasite (parasitic insect) Category:Arthropods (Insects) Transmission Type:Direct contact (head-to-head), rarely via shared personal items Primary Target Area:Scalp and hair Lifecycle Form:Nit (egg), nymph, adult louse Incubation Period:Eggs hatch within 7 to 10 days; itching may develop weeks after initial infestation. Transmission: Head ... Read more

Plasmodium falciparum

Plasmodium falciparum (also referred to as the malignant or tropical malaria parasite) Plasmodium Falciparum Details: Type:Single-celled parasitic protozoan Category:Blood & tissue protozoa Transmission Type:Mosquito-borne (via infected Anopheles mosquitoes) Primary Target Area:Liver cells and red blood cells Lifecycle Form:Exists in multiple forms — sporozoites (infective form injected by mosquito), merozoites (blood-stage replicating form), and gametocytes (sexual ... Read more

Plasmodium knowlesi

Plasmodium knowlesi Plasmodium knowlesi (also referred to as P. knowlesi) Plasmodium knowlesi Details: Type: Protozoan parasite (single-celled organism) Category: Blood parasite (malarial parasite) Transmission Type: Vector-borne (mosquito transmission) Primary Target Area: Red blood cells (circulatory system) Lifecycle Form: Exists in multiple stages — sporozoite (infective form transmitted by mosquitoes), liver stage (hepatic schizont), and blood ... Read more

Plasmodium malariae

Plasmodium malariae (also referred to as the quartan malaria parasite) Giardia lamblia Details: Type:Single-celled parasitic protozoan Category:Blood & tissue protozoa Transmission Type:Mosquito-borne Primary Target Area:Red blood cells Lifecycle Form:Exists in multiple forms — sporozoites (infective form), merozoites (blood-stage replicating form), gametocytes (sexual form). Incubation Period:Symptoms usually appear 18–40 days after infection, though low-level infections can ... Read more

Plasmodium ovale

Plasmodium ovale (also referred to as the tertian malaria parasite) Plasmodium ovale Details: Type:Single-celled parasitic protozoan Category:Blood & tissue protozoa Transmission Type:Mosquito-borne Primary Target Area:Liver cells and red blood cells Lifecycle Form:Exists in multiple forms — sporozoites (infective form), merozoites (blood-stage replicating form), gametocytes (sexual form), and hypnozoites (dormant liver stage causing relapse) Incubation Period:Symptoms ... Read more

Plasmodium vivax

Plasmodium vivax (also referred to as the benign tertian malaria parasite) Plasmodium vivax Details: Type:Single-celled parasitic protozoan Category:Blood & tissue protozoa Transmission Type:Mosquito-borne Primary Target Area:Liver cells and red blood cells Lifecycle Form:Exists in multiple forms — sporozoites (infective form), merozoites (blood-stage replicating form), gametocytes (sexual form), and hypnozoites (dormant liver stage causing relapse) Incubation ... Read more

Pthirus pubis (Pubic Lice)

Pthirus pubis (commonly referred to as pubic lice or “crabs”) Pthirus pubis Details: Type:Ectoparasite (parasitic insect) Category:Arthropods (Insects) Transmission Type:Direct close contact (most commonly sexual contact) Primary Target Area:Pubic hair (may also affect coarse hair such as armpits, beard, chest, eyelashes) Lifecycle Form:Nit (egg), nymph, adult louse Incubation Period:Eggs hatch within 6 to 10 days; ... Read more

Pulex irritans (Human Flea)

Pulex irritans (commonly referred to as the human flea) Pulex irritans Details: Type:Ectoparasite (blood-feeding insect) Category:Arthropods (Insects) Transmission Type:Environmental exposure (infested bedding, animals, or surroundings) Primary Target Area:Skin (surface feeding) Lifecycle Form:Egg, larva, pupa, adult flea Incubation Period:Bite reactions may appear within minutes to hours after exposure. Transmission: Pulex irritans infests environments and feeds on ... Read more

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Sarcoptes scabiei (Scabies Mite)

Sarcoptes scabiei (commonly referred to as the scabies mite) Sarcoptes scabiei Details: Type:Ectoparasite (microscopic mite) Category:Arthropods (Arachnids) Transmission Type:Prolonged skin-to-skin contact Primary Target Area:Skin (especially between fingers, wrists, elbows, waistline, and genitals) Lifecycle Form:Egg, larva, nymph, adult mite (burrows into skin) Incubation Period:Symptoms typically appear 2 to 6 weeks after first exposure; reinfestation may cause ... Read more

Schistosoma haematobium

Schistosoma haematobium (commonly associated with urinary schistosomiasis) Schistosoma haematobium Details: Type:Helminth (parasitic flatworm) Category:Flukes (Trematodes) Transmission Type:Waterborne (skin penetration by larval stage) Primary Target Area:Blood vessels of the urinary tract, bladder Lifecycle Form:Cercariae (free-swimming infective larval stage), schistosomula, adult worms (blood vessel stage), eggs Incubation Period:Early symptoms may develop within weeks of exposure; chronic disease ... Read more

Schistosoma japonicum

Schistosoma japonicum (commonly associated with intestinal and hepatosplenic schistosomiasis) Schistosoma japonicum Details: Type:Helminth (parasitic flatworm) Category:Flukes (Trematodes) Transmission Type:Waterborne (skin penetration by larval stage) Primary Target Area:Intestinal blood vessels (mesenteric veins), liver Lifecycle Form:Cercariae (free-swimming infective larval stage), schistosomula, adult worms (blood vessel stage), eggs Incubation Period:Early symptoms may appear within weeks after exposure; chronic ... Read more

Schistosoma mansoni

Schistosoma mansoni (commonly associated with intestinal schistosomiasis) Schistosoma mansoni Details: Type:Helminth (parasitic flatworm) Category:Flukes (Trematodes) Transmission Type:Waterborne (skin penetration by larval stage) Primary Target Area:Intestinal blood vessels (mesenteric veins), liver Lifecycle Form:Cercariae (free-swimming infective larval stage), schistosomula, adult worms (blood vessel stage), eggs Incubation Period:Early symptoms may appear within weeks after exposure; chronic disease can ... Read more

Strongyloides stercoralis

Strongyloides stercoralis (also referred to as S. stercoralis) Strongyloides stercoralis Details: Type:Helminth (parasitic roundworm) Category:Intestinal nematode (soil-transmitted helminth) Transmission Type:Skin penetration (soil-transmitted) Primary Target Area:Small intestine (with potential systemic spread in severe cases) Lifecycle Form:Filariform larva (infective stage), rhabditiform larva, adult worm (intestinal stage) Incubation Period:Initial symptoms may develop within days to weeks after skin ... Read more

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Taenia saginata (Beef Tapeworm)

Taenia saginata (commonly referred to as the beef tapeworm) Taenia saginata Details: Type:Helminth (parasitic tapeworm) Category:Intestinal cestode Transmission Type:Foodborne (consumption of undercooked beef) Primary Target Area:Small intestine Lifecycle Form:Cysticercus (larval stage in cattle, infective to humans), adult tapeworm (intestinal stage in humans) Incubation Period:Adult worms typically develop within 8 to 12 weeks after ingestion of ... Read more

Taenia solium (Pork Tapeworm)

Taenia solium (commonly referred to as the pork tapeworm) Taenia solium Details: Type:Helminth (parasitic tapeworm) Category:Intestinal cestode (with potential tissue involvement) Transmission Type:Foodborne (undercooked pork), fecal-oral (egg ingestion) Primary Target Area:Small intestine (adult worm stage), muscles, brain, eyes (larval cyst stage) Lifecycle Form:Cysticercus (larval stage in pigs and sometimes humans), adult tapeworm (intestinal stage in ... Read more

Thelazia Species (Eye Worm)

Thelazia species (commonly referred to as eye worms) Thelazia Species Details: Type:Helminth (parasitic roundworm) Category:Nematodes (Roundworms) Transmission Type:Vector-borne (transmitted by flies) Primary Target Area:Eyes (conjunctival sac, tear ducts) Lifecycle Form:Larval stage (transmitted by flies), adult worm (resides in eye tissues) Incubation Period:Symptoms may develop days to weeks after exposure. Transmission: Thelazia species are transmitted when ... Read more

Toxocara canis

Toxocara canis (commonly referred to as dog roundworm) Toxocara canis Details: Type:Helminth (parasitic roundworm) Category:Zoonotic nematode Transmission Type:Fecal-oral (soil-transmitted, zoonotic) Primary Target Area:Multiple organs (liver, lungs, eyes, central nervous system) Lifecycle Form:Egg (infective form), larval stage (migratory in humans), adult worm (in dogs only) Incubation Period:Symptoms may develop weeks to months after ingestion of infective ... Read more

Toxocara cati

Toxocara cati (commonly referred to as cat roundworm) Toxocara cati Details: Type:Helminth (parasitic roundworm) Category:Zoonotic nematode Transmission Type:Fecal-oral (soil-transmitted, zoonotic) Primary Target Area:Multiple organs (liver, lungs, eyes, central nervous system) Lifecycle Form:Egg (infective form), larval stage (migratory in humans), adult worm (in cats only) Incubation Period:Symptoms may develop weeks to months after ingestion of infective ... Read more

Toxoplasma gondii

Toxoplasma gondii (also referred to as T. gondii) Toxoplasma gondii Details: Type: Protozoan parasite (single-celled organism) Category: Intracellular protozoa (tissue parasite) Transmission Type: Foodborne, zoonotic, congenital Primary Target Area: Muscle tissue, brain, eyes, and other organs Lifecycle Form: Exists in multiple forms — oocyst (shed in cat feces), tachyzoite (rapidly multiplying form), and bradyzoite (slow-growing ... Read more

Trichinella spiralis

Trichinella spiralis (also referred to as T. spiralis) Trichinella spiralis Details: Type:Helminth (parasitic roundworm) Category:Tissue nematode Transmission Type:Foodborne (zoonotic) Primary Target Area:Small intestine (initial stage), skeletal muscle (larval stage) Lifecycle Form:Encysted larva (infective form in meat), adult worm (intestinal stage), migrating larva (muscle stage) Incubation Period:Gastrointestinal symptoms may develop within 1 to 2 days after ... Read more

Trichuris trichiura (whipworm)

Trichuris trichiura (commonly referred to as whipworm) Trichuris trichiura Details: Type: Helminth (parasitic roundworm) Category: Intestinal nematode (soil-transmitted helminth) Transmission Type: Fecal-oral (soil-transmitted) Primary Target Area: Large intestine (colon and cecum) Lifecycle Form: Egg (infective form), larval stage, adult worm (intestinal stage) Incubation Period: Symptoms typically develop 1 to 3 months after ingestion of infective ... Read more

Trypanosoma brucei

Trypanosoma brucei (also referred to as T. brucei) Trypanosoma brucei Details: Type:Protozoan parasite (single-celled organism) Category:Blood and tissue protozoa (hemoflagellate parasite) Transmission Type:Vector-borne (tsetse fly transmission) Primary Target Area:Bloodstream, lymphatic system, central nervous system Lifecycle Form:Trypomastigote (circulating infective form in humans), epimastigote (form within the tsetse fly vector) Incubation Period:Symptoms may develop within days to ... Read more

Trypanosoma cruzi

Trypanosoma cruzi (also referred to as T. cruzi) Trypanosoma cruzi Details: Type: Protozoan parasite (single-celled organism) Category: Blood and tissue protozoa (hemoflagellate parasite) Transmission Type: Vector-borne, congenital, bloodborne, foodborne Primary Target Area: Bloodstream, heart tissue, digestive tract (esophagus and colon) Lifecycle Form: Exists in multiple forms — trypomastigote (circulating infective form), amastigote (intracellular replicative form), ... Read more

Tunga penetrans (Sand Flea)

Tunga penetrans (commonly referred to as the sand flea or chigoe flea) Tunga penetrans Details: Type:Ectoparasite (burrowing flea) Category:Arthropods (Insects) Transmission Type:Skin penetration (environmental exposure) Primary Target Area:Skin of feet (especially toes, soles, and under toenails) Lifecycle Form:Egg, larva, pupa (environmental stages), adult flea (female burrows into skin) Incubation Period:Symptoms typically begin within days after ... Read more

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Wuchereria bancrofti

Wuchereria bancrofti (also referred to as W. bancrofti) Wuchereria bancrofti Details: Type:Helminth (parasitic roundworm) Category:Filarial nematode (lymphatic parasite) Transmission Type:Vector-borne (mosquito transmission) Primary Target Area:Lymphatic system Lifecycle Form:Microfilariae (circulating larval stage), adult worm (lymphatic vessel stage) Incubation Period:Infection may remain asymptomatic for months to years before symptoms develop. Transmission: Wuchereria bancrofti is transmitted through the ... Read more