Rishi Desai, MD, MPH

Ancylostoma duodenale and Necator americanus

Wikipedia

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Chapter 82 Nematodes (Roundworms)  ANCYLOSTOMA DUODENALE & NECATOR AMERICANUS osms.it/ancylostoma-duodenale osms.it/necator-americanus PATHOLOGY & CAUSES ▪ Infectious hookworm species Adult morphology ▪ Ancylostoma duodenale ▫ Two ventral plates on buccal capsule’s anterior margin; two large teeth fused at base (male 8–11mm, female 10–13mm long) ▪ Necator americanus ▫ Two dorsal/ventral cutting plates around buccal capsule’s anterior margin, paired subdorsal/subventral teeth (male 7–9mm, female 9–11mm long) ▪ A. duodenale, Necator americanus: most common hookworm species causing helminth gastrointestinal infection ▫ Light infection (< 100 worms) ▫ Moderate infection (100–500 worms) ▫ Heavy infection (500–1000 worms) ▪ Pathophysiology ▫ Hookworm attachment, hyaluronidase release → intestinal wall degradation, capillary laceration → anticoagulant peptides, inhibits platelet function inhibitor production → bleeding facilitation → extravasated blood ingested (approx. 0.5mL daily) ▫ Moderate–heavy infections → chronic iron-deﬁciency anemia; protein malnutrition Infectious form ▪ Filariform larva Life cycle ▪ Infectious form maturation ▫ Female A. duodenale lays 10,000– 30,000 eggs daily  ▫ Female N. americanus lays 5,000– 10,000 eggs daily ▫ Human feces egge release → soil deposition → eggs hatch (24–48 hours—favorable conditions) → rhabditiform larvae (L1) → transformation to infectious ﬁlariform larvae (L3) in 5–10 days ▪ Human stages ▫ Filariform larvae skin penetration → passage through veins to heart, lung → pulmonary alveoli penetration, ascend bronchi to pharynx → coughed up/swallowed into small intestine → maturation → intestinal wall attachment via buccal capsule ▪ Some A. duodenale larvae undergo developmental arrest in gut tissues/muscle ▫ Await more favorable environmental conditions (hypobiotic larvae) ▪ Natural life-span ▫ A. duodenale: approx. one year ▫ N. americanus: 3–5 years Transmission ▪ Contaminated soil contact → percutaneous larval penetration ▪ Oral route ▪ Transmammary route  RISK FACTORS  ▪ Inadequate clean-water access ▪ Poor sanitary conditions ▪ Walking barefoot (endemic areas)  COMPLICATIONS  ▪ Severe iron-deﬁciency anemia; protein malnutrition → impaired growth, cognitive  OSMOSIS.ORG 437   

Hookworm Infection

Bacterial structure and functions

Introduction to bacteria

Staphylococcus epidermidis

Staphylococcus aureus

Staphylococcus saprophyticus

Streptococcus viridans

Streptococcus pneumoniae

Streptococcus pyogenes (Group A Strep)

Streptococcus agalactiae (Group B Strep)

Enterococcus

Clostridium perfringens

Clostridium botulinum (Botulism)

Clostridium difficile (Pseudomembranous colitis)

Clostridium tetani (Tetanus)

Bacillus cereus (Food poisoning)

Listeria monocytogenes

Corynebacterium diphtheriae (Diphtheria)

Bacillus anthracis (Anthrax)

Nocardia

Actinomyces israelii

Gram positive bacteria

Escherichia coli

Salmonella (non-typhoidal)

Salmonella typhi (typhoid fever)

Pseudomonas aeruginosa

Enterobacter

Klebsiella pneumoniae

Shigella

Proteus mirabilis

Yersinia enterocolitica

Legionella pneumophila (Legionnaires disease and Pontiac fever)

Serratia marcescens

Bacteroides fragilis

Yersinia pestis (Plague)

Vibrio cholerae (Cholera)

Helicobacter pylori

Campylobacter jejuni

Neisseria meningitidis

Neisseria gonorrhoeae

Moraxella catarrhalis

Francisella tularensis (Tularemia)

Bordetella pertussis (Pertussis/Whooping cough)

Brucella

Haemophilus influenzae

Haemophilus ducreyi (Chancroid)

Pasteurella multocida

Gram negative bacteria

Mycobacterium tuberculosis (Tuberculosis)

Mycobacterium leprae

Mycobacterium avium complex (NORD)

Mycobacteria

Mycoplasma pneumoniae

Chlamydia pneumoniae

Chlamydia trachomatis

Borrelia burgdorferi (Lyme disease)

Borrelia species (Relapsing fever)

Leptospira

Treponema pallidum (Syphilis)

Rickettsia rickettsii (Rocky Mountain spotted fever) and other Rickettsia species

Coxiella burnetii (Q fever)

Ehrlichia and Anaplasma

Gardnerella vaginalis (Bacterial vaginosis)

Other bacteria

Bacteriology

Viral structure and functions

Introduction to viruses

Varicella zoster virus

Cytomegalovirus

Epstein-Barr virus (Infectious mononucleosis)

Human herpesvirus 8 (Kaposi sarcoma)

Herpes simplex virus

Human herpesvirus 6 (Roseola)

Adenovirus

Parvovirus B19

Hepatitis B and Hepatitis D virus

Human papillomavirus

Poxvirus (Smallpox and Molluscum contagiosum)

BK virus (Hemorrhagic cystitis)

JC virus (Progressive multifocal leukoencephalopathy)

DNA viruses

Poliovirus

Coxsackievirus

Rhinovirus

Hepatitis A and Hepatitis E virus

Influenza virus

Mumps virus

Measles virus

Respiratory syncytial virus

Human parainfluenza viruses

Dengue virus

Yellow fever virus

Zika virus

Hepatitis C virus

West Nile virus

Norovirus

Rotavirus

Coronaviruses

HIV (AIDS)

Human T-lymphotropic virus

Ebola virus

Rabies virus

Rubella virus

Eastern and Western equine encephalitis virus

Lymphocytic choriomeningitis virus

Hantavirus

RNA viruses

Prions (Spongiform encephalopathy)

Prions and virioids

Virology

Coccidioidomycosis and paracoccidioidomycosis

Histoplasmosis

Blastomycosis

Systemic fungal infections

Pneumocystis jirovecii (Pneumocystis pneumonia)

Candida

Mucormycosis

Aspergillus fumigatus

Sporothrix schenckii

Cryptococcus neoformans

Opportunistic fungal infections

Malassezia (Tinea versicolor and Seborrhoeic dermatitis)

Cutaneous fungal infections

Mycology

Plasmodium species (Malaria)

Babesia

Giardia lamblia

Entamoeba histolytica (Amebiasis)

Cryptosporidium

Acanthamoeba

Naegleria fowleri (Primary amebic meningoencephalitis)

Toxoplasma gondii (Toxoplasmosis)

Trypanosoma brucei

Trypanosoma cruzi (Chagas disease)

Trichomonas vaginalis

Leishmania

Protozoa

Loa loa (Eye worm)

Toxocara canis (Visceral larva migrans)

Onchocerca volvulus (River blindness)

Ascaris lumbricoides

Anisakis

Angiostrongylus (Eosinophilic meningitis)

Strongyloides stercoralis

Guinea worm (Dracunculiasis)

Wuchereria bancrofti (Lymphatic filariasis)

Trichinella spiralis

Enterobius vermicularis (Pinworm)

Trichuris trichiura (Whipworm)

Echinococcus granulosus (Hydatid disease)

Diphyllobothrium latum

Paragonimus westermani

Clonorchis sinensis

Schistosomes

Worms

Pediculus humanus and Phthirus pubis (Lice)

Sarcoptes scabiei (Scabies)

Ectoparasites

Parasitology

Protein synthesis inhibitors: Aminoglycosides

Antimetabolites: Sulfonamides and trimethoprim

Antituberculosis medications

Miscellaneous cell wall synthesis inhibitors

Protein synthesis inhibitors: Tetracyclines

Cell wall synthesis inhibitors: Penicillins

Miscellaneous protein synthesis inhibitors

Cell wall synthesis inhibitors: Cephalosporins

DNA synthesis inhibitors: Metronidazole

DNA synthesis inhibitors: Fluoroquinolones

Mechanisms of antibiotic resistance

Antibiotics

Integrase and entry inhibitors

Nucleoside reverse transcriptase inhibitors (NRTIs)

Protease inhibitors

Hepatitis medications

Non-nucleoside reverse transcriptase inhibitors (NNRTIs)

Neuraminidase inhibitors

Herpesvirus medications

Antivirals

Azoles

Echinocandins

Miscellaneous antifungal medications

Antifungals

Anthelmintic medications

Antimalarials

Anti-mite and louse medications

Antiparasitics

Pharmacology

Ancylostoma duodenale and Necator americanus

Videos

Notes