Helminthology Nematodes Nematodes Helminthology Hookworm - PowerPoint PPT Presentation

Helminthology – – Nematodes Nematodes Helminthology Hookworm Hookworm Terry L Dwelle Dwelle MD MPHTM MD MPHTM Terry L 1 1

Classification of Nematodes Classification of Nematodes Superfamily Genus and Species Probable Subclass Subclass Order Order Superfamily Genus and Species Probable (suborder) prevalence in (suborder) prevalence in man man Secernentea Strongylida Ankylostomatoidea Ankylostoma douodenale douodenale 716 million Secernentea Strongylida Ankylostomatoidea Ankylostoma 716 million Necator americanus americanus Necator A caninum caninum Thousands A Thousands A braziliense braziliense Thousands A Thousands A ceylanicum ceylanicum Rare A Rare Ternidens diminutus diminutus Thousands Ternidens Thousands Oesophagostomum Rare Oesophagostomum Rare apiostomum apiostomum Syngamus laryngeus laryngeus Rare Syngamus Rare 2

General Information General Information ► Two major species; ► Two major species; Ankylostoma Ankylostoma duodenale duodenale (old world), Necator Necator Americanus Americanus (new (new (old world), world) world) ► Others; A ► Others; A caninum caninum, A , A braziliense braziliense, A , A ceylanicum ceylanicum ► Prevalence ► Prevalence – – Africa, Asia, Central America, Africa, Asia, Central America, South America, Caribbean Islands, SE US South America, Caribbean Islands, SE US 3

General Recognition Features General Recognition Features ► Size ► Size � Necator � Necator americanis americanis – – male 7 male 7- -9 mm, female 10 9 mm, female 10- -18 mm 18 mm � Ankylostoma � Ankylostoma duodenale duodenale – – male 8 male 8- -11 mm, female 10 11 mm, female 10- -15 15 mm mm ► Structure Structure ► � NA has a fused � NA has a fused copulatory copulatory spicule spicule vs vs AD AD � AD totally dorsally flexed. NA is dorsally flexed but with � AD totally dorsally flexed. NA is dorsally flexed but with a ventral flex near the head a ventral flex near the head � Two sets of reproductive organs � Two sets of reproductive organs � Distinctive mouth parts � Distinctive mouth parts � Copulatory � Copulatory bursa ray patterns are distinctive bursa ray patterns are distinctive ► Eggs Eggs ► 4 to 8 cells � Thin shelled � Thin shelled � 60 � 60- -75 um X 35 75 um X 35- -40 um 40 um 4

General Recognition Features General Recognition Features ► Structure ► Structure � � NA has a fused copulatory copulatory spicule spicule NA has a fused vs AD AD vs � � AD totally dorsally flexed. NA is AD totally dorsally flexed. NA is dorsally flexed but with a ventral dorsally flexed but with a ventral flex near the head flex near the head � � Two sets of reproductive organs Two sets of reproductive organs � � Copulatory bursa ray patterns are bursa ray patterns are Copulatory distinctive for male worms distinctive for male worms From Manson’s Tropical Disease, 20 th Edition, Saunders, pp 1621 5

General Recognition Features General Recognition Features From Manson’s Tropical Disease, 20th Edition, Saunders, pp 1622 6

General Recognition Features General Recognition Features A Caninum A Duodenale From a Color Atlas of Tropical Medicine and Parasitology, 2 nd edition, Yearbook Medical Publishers, pp 148-149 N Americanus A Ceylanicum 7

General Recognition Features General Recognition Features From Manson’s Tropical Disease, 20th Edition, Saunders, pp 1621-1622 8

General Recognition Features General Recognition Features From a Color Atlas of Tropical Medicine and Parasitology, 2nd edition, Yearbook Medical Publishers, pp 148-149 9

General Recognition Features General Recognition Features 10

Life Cycle Life Cycle ► Definitive host ► Definitive host – – man man ► Stage leaving the body ► Stage leaving the body – – fertile eggs fertile eggs ► Infectious stage for the definitive host ► Infectious stage for the definitive host – – L3 L3 larvae larvae 11

Prepatency and Incubation Period and Incubation Period Prepatency ► Prepatency ► Prepatency – – 8 8- -12 weeks 12 weeks ► Incubation period ► Incubation period – – 4 4- -12 weeks 12 weeks 12

Life Cycle Life Cycle L3 Filariform Larvae Penetrates skin within a few minutes L1 rhabdiform Larvae Skin GI Meat 24-48 hours Breast Milk Soil loose, sandy Blood Rhabditis like esophagus Eggs 5000/day NA, 20,000/day AD Lungs AD 5-7w, NA 4-6w 6 – 10 days Small Intestine Largnx Life span 5-10 years Esophagus 13

Life Cycle Life Cycle L3 Filariform Larvae Penetrates skin within a few minutes L1 rhabdiform Larvae Skin GI Meat 24-48 hours Breast Milk Soil loose, sandy Blood Rhabditis like esophagus Eggs 5000/day NA, 20,000/day AD Lungs 6 – 10 days Small Intestine Largnx Life span 5-15 years Esophagus 14

15

Signs and Symptoms Signs and Symptoms ► Ground itch due to ► Ground itch due to vesiculation vesiculation and and pustulation pustulation at at the entry site the entry site � Exposed portions of the body usually the soles of the � Exposed portions of the body usually the soles of the feet or hands feet or hands ► Asthma and bronchitis caused by migration of the ► Asthma and bronchitis caused by migration of the larvae through the lungs larvae through the lungs � 1 � 1- -2 weeks associated with dry cough and wheezing 2 weeks associated with dry cough and wheezing ► Established infection associated with hookworm Established infection associated with hookworm ► disease disease 16

Established Infection Established Infection • Light infection ( Light infection (< < 100 worms) 100 worms) • Mild anemia • Mild anemia • Fatique • Fatique • Lassitude • Lassitude • Digestive disturbances • Digestive disturbances • Eosinophilia • Eosinophilia • 17

Established Infection Established Infection • Heavy infection ( • Heavy infection (> > 400 worms) 400 worms) – – Fatique • Fatique • Lassitude • Lassitude • Eosinophilia • Eosinophilia • Epigastric apin apin • Epigastric • Perverted taste – – pica, pica, geophagy geophagy • Perverted taste • Hematochezia / / melena melena • Hematochezia • Anemia • Anemia • Edema associated with hypoalbuminemia hypoalbuminemia • Edema associated with • Heart failure • Heart failure • Hypothermia • Hypothermia • Retinal hemorrhages • Retinal hemorrhages • Irregular fever • Irregular fever • Growth failure • Growth failure • 18

Wakana disease disease Wakana ► Associated with oral infection with AD in ► Associated with oral infection with AD in Japan Japan ► No larvae are found in the lung ► No larvae are found in the lung ► Has cough, ► Has cough, dyspnea dyspnea, , eosinophilia eosinophilia, nausea , nausea and vomiting and vomiting ► Seen one to several days after ingestion of ► Seen one to several days after ingestion of larvae larvae ► Etiology is not known ► Etiology is not known 19

Infantile Disease Infantile Disease ► Mostly reported from China ► Mostly reported from China ► Mainly caused by A ► Mainly caused by A Duodenale Duodenale ► Transmission ► Transmission – – trans trans- -mammary, laying mammary, laying infants on infected soil, and rarely trans- - infants on infected soil, and rarely trans placental placental ► Signs and symptoms ► Signs and symptoms – – diarrhea, diarrhea, hematochezia / / melena melena, anorexia, vomiting, , anorexia, vomiting, hematochezia pallor, massive hemorrhage pallor, massive hemorrhage ► Mortality ► Mortality – – 12% 12% 20

21

Diagnosis Diagnosis ► Eggs in the stool ► Eggs in the stool � Heavy infection � Heavy infection – – Direct stool smear with saline or Direct stool smear with saline or potassium iodide saturated with iodine potassium iodide saturated with iodine � Light infection � Light infection – – Concentration Concentration techiques techiques (Kato (Kato- -Katz, Katz, Beaver direct smear, Stoll egg counting techique techique) ) Beaver direct smear, Stoll egg counting � Late � Late prepatent prepatent period Charcot Leyden crystals and period Charcot Leyden crystals and eosinophils may be seen in the feces similar to may be seen in the feces similar to eosinophils whipworm whipworm � > 20 eggs / mg associated with anemia in NA � > 20 eggs / mg associated with anemia in NA vs vs > 5 > 5 eggs / mg with AD eggs / mg with AD 22

Hookworm Hookworm Capillaria Philippinensis Hookworm Egg Trichostrongylus Strongyloides stercoralis larva Trichostrongylus Egg Trichuris trichuria Hookworm 23

Treatment Treatment Drug Adult Pediatric Drug Adult Pediatric Albendazole 400 mg once 400 mg once Albendazole 400 mg once 400 mg once Mebendazole 100 mg bid X 3 100 mg bid X 3 Mebendazole 100 mg bid X 3 100 mg bid X 3 days or 500 mg days or 500 mg days or 500 mg days or 500 mg once once once once Pyrantel 11 mg/kg (max 11 mg/kg (max Pyrantel 11 mg/kg (max 11 mg/kg (max pamoate 1 gm) X 3 days 1 gm) X 3 days pamoate 1 gm) X 3 days 1 gm) X 3 days 24