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