Moraxella
Classification Characteristics Features: Stain: gram-negative Morphology: diplococcus Nonmotile Growth and culture: Microaerophilic Oxidase-positive, catalase-positive Asaccharolytic (does not ferment carbohydrates) M. catarrhalis and M. lacunata are the most clinically relevant species within this genus. Pathogenesis Transmission Humans are the primary reservoir. M. catarrhalis spreads from person to person via respiratory droplets. Nasopharyngeal colonization: Common in infancy, […]
Taenia/Taeniasis
General Characteristics and Epidemiology General features of Taenia Taenia is a genus of parasitic cestodes (tapeworms). Eggs: Adults: Clinically relevant species Taenia tapeworms cause the following diseases: Epidemiology Geographic distribution of species: Taeniasis: Cysticercosis: Pathogenesis Hosts Risk factors for hosts Transmission Life cycle and pathophysiology Taeniasis: Cysticercosis: Clinical Presentation Taeniasis Most patients (particularly adults) are […]
Enterobius/Enterobiasis
General Characteristics and Epidemiology Basic features of Enterobius Nematode Appearance: White Slender Pointed, pin-like tail in females Size: Females: 8–13 mm long Males: 2–5 mm long Eggs: Elongated Flattened on 1 side Translucent Clinically relevant species Enterobius vermicularis, or pinworm, causes enterobiasis. Epidemiology Enterobiasis is the most common helminth infection in the United States and […]
Diphyllobothrium/Diphyllobothriasis
General Characteristics and Epidemiology General features of Diphyllobothrium Diphyllobothriasis is caused by a parasitic infection from the cestode (tapeworm) Diphyllobothrium. The largest human parasite (length up to 10 meters) Adult morphology: Scolex No hooks Paired slit-like attachment grooves (bothria) Neck Strobila with up to 3,000–4,000 proglottids Segmented Contains sets of reproductive organs Eggs: Ellipsoidal or […]
Echinococcus/Echinococcosis
General Characteristics and Epidemiology General features of Echinococcosis Echinococcosis is a parasitic disease caused by Echinococcus tapeworms. Features include: Eggs: Small Round Thick-shelled Contain a 6-hooked (hexacanth) embryo Adults: Small (1.2–7 mm long, depending on the species) Ribbon-like body shape: Scolex: Hook-filled rostellum 4 lateral suckers Neck Strobila with 3–6 proglottids: Segmented Contain sets of […]
Toxocariasis
General Characteristics and Epidemiology Basic features of Toxocara Nematode (roundworm) A dioecious helminth (males and females have different morphologies): Females are longer than males. Males have a curved tail with paired spicules. Size: 4–12 cm long Have complete digestive systems Move in contractile waves Eggs: Brownish Spherical Granulated or pitted surface Very resistant to adverse […]
Coxiella/Q Fever
General Characteristics of Coxiella General features of Coxiella Clinically relevant species Coxiella burnetii causes Q fever. Epidemiology and Pathogenesis Epidemiology Reservoir Routes of transmission Host risk factors Virulence factors Antigenic phase variation: Morphological variants: Escape from intracellular killing: Pathophysiology Clinical Presentation Patients may present with a wide range of symptoms, and vary in severity from […]
Trichinella/Trichinellosis
General Characteristics Basic features of Trichinella Intestinal and tissue nematode (roundworm) Intracellular parasite Associated disease: trichinellosis Clinically relevant species Most notable and worldwide: Trichinella spiralis Causes of trichinellosis: Encapsulating/encysting (within host muscles): Trichinella britovi (Europe, Asia, and northern and western Africa) Trichinella murelli (North America) Trichinella nativa (Arctics) Trichinella nelsoni (Eastern Africa) Nonencapsulating: Trichinella papuae […]
Hookworm Infections
Overview General characteristics Hookworms: Average length of adult worm: 10 mm Head is often curved in the opposite direction of the body: worms have a “hooked” appearance. Male worms have a unique copulatory bursa instead of the curved, pointed tail seen in other intestinal nematodes. Major species of hookworms that cause human infections: Ancylostoma duodenale: […]
Plasmodium/Malaria
Overview Definition Malaria is a parasitic disease caused by unicellular parasites of the Plasmodium genus and transmitted by mosquitoes of the Anopheles genus. Epidemiology Malaria occurs throughout most of the tropical regions of Africa, Central and South America, parts of the Caribbean, Asia, Eastern Europe, and the South Pacific. In 2019, the WHO reported 229 […]