Global Health Pre-Trip Session Helminthic infections seen in developing nations:

Neglected Tropical Diseases!

Paul M Southern, MD, DTM&H

2013

Diseases to be covered

� Ascariasis: Ascaris lumbricoides

� Echinococcosis (cystic hydatid): Echinococcus granulosus

� Hookworm: Ancylostoma duodenale, Necator americanus

� Lymphatic filariasis: Wuchereria bancrofti, Brugia malayi, B. timori

� Onchocerciasis: Onchocerca volvulus

� Schistosomiasis: Schistosoma mansoni, S. haematobium, S. japonicum, S. intercalatum, S. mekongi

� Strongyloidiasis: Stongyloides stercoralis

� Taeniasis: Taenia solium, T. saginata, cysticercosis

� Trichuriasis: Trichuris trichiura

Diseases NOT covered

� Enterobiasis (pinworm): Enterobius vermicularis

� Filaria (others): Loa loa, Mansonella ozzardi, M. perstans, M. streptocerca, Dirofilaria spp.

� Intestinal cestodes (rarer): Hymenolepis nana, H. diminuta, Dipyllidium caninum, Diphyllobothrium latum, agents of Sparganosis

� Intestinal nematodes (rarer): Capillaria philippinensis, Trichostrongylus spp.

� Other trematodes: intestinal, liver, lung

� Tissue nematodes: many

� Not covering ANY protozoa, despite their great importance

Global Estimates of number of soil-transmitted helminths (millions), WHO

� Ascariasis: 1,222

� Trichuriasis: 795

� Hookworm: 740

� Strongyloidiasis: ~500*

* = incomplete data

Estimated number of DALYs lost (thousands) by cause [helminths only]*

� Schistosomiasis: 1,707 worldwide, 1,502 Africa

� Lymphatic filariasis: 5,941 worldwide, 2,263 Africa, 3,525 SE Asia

� Onchocerciasis: 389 worldwide, 375 Africa

� Ascariasis: 1,851 worldwide, 915 Africa, 404 SE Asia

� Hookworm: 1,092 worldwide, 377 Africa, 286 SE Asia

* WHO data; DALY = disability-adjusted life years

Cost-effectiveness of controlling neglected tropical diseases (Cost per DALY averted in $US)

� Lymphatic filariasis: 35 – 370 (depends on region)

� Schistosomiasis: 10-23, or as much as 844 (depends on strategy)

� Onchocerciasis: 9

� Soil-transmitted helminths: 2-11 (mass school treatment) (Includes hookworm, ascariasis, whipworm)

WHO-recommended anthelminthic drugs for treatment or prevention

Disease Albend-azole

Mebend-azole

Diethyl-carbam-ezine

Ivermectin Prazi-quantel

Levam-isole

Pyrantel

Ascariasis + + - (+) - + + Hookworm + + - - - + + Lymphatic filariasis

+ - + + - - -

Oncho-cerciasis - - - + - - -

Schisto- somiasis

- - - - + - -

Trichuriasis + + - (+) - (?) (?) Other flukes

- - - - + - -

Strongyloid-iasis + (+) - + - - - Taeniasis - - - - + - -

Morbidity associated with soil-transmitted helminths*

� Intestinal bleeding: Hookworm

� Malabsorption syndromes: Ascariasis

� Competition for micronutrients: Ascariasis

� Impaired growth: Ascariasis

� Anorexia, reduced food intake: Ascariasis

� Diarrhea or dysentery: Trichuriasis

� Cognitive impairment: Trichuriasis

� Intestinal obstruction: Ascariasis

� Rectal prolapse: Trichuriasis

* Montresor, et al.TRSTMH.2010;104:129-32

Taenia

Taenia solium

Taenia saginata

T. saginata T. solium

CLASSIFICATION OF PATHOGENIC AND COMMENSAL HUMAN PARASITES

B. TISSUE CESTODES (Larval) 1. Taenia solium (cysticercoisis)

2. Echinococcus granulosus (hydatid cysts)

3. Echinococcus multilocularis (alveolar hydatid)

4. Multiceps spp. (Taenia multiceps) “Coenurosis”, “Coenuriasis”

5. Spirometra mansoni, Spirometra mansonoides, others (Sparganosis)

ECHINOCOCCOSIS (Hydatid Disease)

Causative Agents: Echinococcus granulosus Unilocular, simple cysts, cystic hydatid Echinococcus multilocularis Alveolar, complex cysts

Echinococcus oligarthrus}

Echinococcus vogeli }

Manifestations: Cysts in liver, spleen, lung, bone, kidney, muscles, brain, myocardium

Diagnosis: Clinical history and examination, imaging techniques, serological tests (ELISA, CF, IHA, arc-5 double-diffusion assay, enzyme-linked immunotransfer blot), hydatid sand in cyst at surgery

Treatment: Surgery, pre-and postoperative albendazole with or without praziquantel (scolicidal); albendazole dosage 400 mg BID X 28 days, repeat if necessary; PAIR

Polycystic hydatid

Echinoccosis granulosus

CT Scan of Abdomen,transverse

CT Scan of Abdomen, vertical

View at Surgery

Surgical specimen from prior patient

Intestinal obstruction due to Ascaris lumbricoides

Hookworm Life Cycle

Larva currens

Rhabditiform larva of Strongyloides stercoralis

Strongyloides stercoralis on stool culture plate

P A

Taken from:

Wuchereria bancrofti microfilaria in peripheral blood

nuclei tip

sheath

Brugia malayi microfilaria

Brugia malayi, separation of last nuclei

Onchocerca volvulus, life cycle

Geography of epidemiology

Black fly, (Simulium damnosum)

Schistosome Map, 2006

Major Schistosomes, life cycle

Egg Schistosoma intercalatum

Schistosoma spp. epidemiology

Epidemiology of S. mansoni and S. haematobium in Africa

Cote d’Ivoire Senegal

Epidemiology of S. mansoni and S. haematobium in Africa

Beautiful Lake Malawi: notorious as a prime site for transmission of schistosomiasis

S. japonicum, mekongi

�Similar pathogenesis as S. mansoni

�More CNS lesions in S. japonicum

�Salmonella bacteremic infections may occur with most species of Schistosoma

S. Japonicum Asia

S. japonicum, Asia

Transmission of S. japonicum in China

Agricultural irrigation ditch

S. japonicum, S. mekongi

The End