This is a list of 52 duck health problems, diseases, and sicknesses, with links to resources about each one.
Viral Diseases
Avian Influenza
http://www.duckdvm.com/condition/avian-influenza
https://www.merckvetmanual.com/poultry/avian-influenza/overview-of-avian-influenza
Circovirus
https://en.wikipedia.org/wiki/Duck_circovirus
http://www.thepoultrysite.com/articles/2051/major-viral-diseases-of-waterfowl-and-their-control/
Duck Virus Enteritis (DVE) / Duck Plague
https://www.msdvetmanual.com/poultry/duck-viral-enteritis/overview-of-duck-viral-enteritis
http://www.duckdvm.com/condition/duck-viral-enteritis
Duck Virus Hepatitis (DVH)
https://www.msdvetmanual.com/poultry/duck-viral-hepatitis/overview-of-duck-viral-hepatitis
http://www.duckdvm.com/condition/duck-viral-hepatitis
Infectious Bronchitis
https://poultrykeeper.com/respiratory-problems/infectious-bronchitis/
https://www.farmhealthonline.com/US/disease-management/poultry-diseases/infectious-bronchitis/
http://www.poultryhub.org/health/disease/types-of-disease/infectious-bronchitis/
Infectious LaryngoTracheitis
https://poultrykeeper.com/respiratory-problems/infectious-laryngiotracheitis-ilt/
http://www.thepoultrysite.com/diseaseinfo/83/infectious-laryngotracheitis-ilt/
Newcastle Disease
http://www.thepoultrysite.com/diseaseinfo/111/newcastle-disease-paramyxovirus-1/
http://www.poultryhub.org/health/disease/types-of-disease/newcastle-disease/
Viral Arthritis / Tenosynovitis
https://www.msdvetmanual.com/poultry/viral-arthritis/overview-of-viral-arthritis-in-poultry
http://wildpro.twycrosszoo.org/S/00dis/viral/Reovirus_infection.htm
http://www.thepoultrysite.com/diseaseinfo/164/viral-arthritis/
http://www.poultryhub.org/health/disease/types-of-disease/viral-arthritis-tenosynovitis/
Bacterial Diseases
Bumblefoot / Staphyloccocus Infection
https://www.fresheggsdaily.com/2012/03/bumblefoot.html
http://www.duckdvm.com/condition/bumblefoot
http://www.poultrydvm.com/condition/bumblefoot
Chlamydiosis
https://poultrykeeper.com/respiratory-problems/chlamydiosis-in-poultry/
Colibacillosis / E.coli
https://www.msdvetmanual.com/poultry/colibacillosis/overview-of-colibacillosis-in-poultry
Mycoplasma Gallisepticum Infection
https://poultrykeeper.com/respiratory-problems/mycoplasma/
https://www.msdvetmanual.com/poultry/mycoplasmosis/mycoplasma-synoviae-infection-in-poultry
https://extension.umaine.edu/livestock/poultry/mycoplasma-gallisepticum-faq/
http://www.poultrydvm.com/pathogens/mycoplasma-gallisepticum
Riemerella Anatipestifer Infection / Pasteurella / Avian Cholera
Salmonellosis
http://www.duckdvm.com/condition/salmonellosis
Spirochetosis
http://www.poultrydvm.com/condition/avian-spirochetosis
https://www.msdvetmanual.com/poultry/avian-spirochetosis/overview-of-avian-spirochetosis
Streptococcal Infection
http://www.thepoultrysite.com/diseaseinfo/92/streptococcus-bovis-septicaemia/
https://en.wikivet.net/Streptococcus_%26_Enterococcus_Infections_-_Poultry
Fungal Infections
Aspergillosis / Mycosis
http://www.duckdvm.com/condition/aspergillosis
Nutritional Deficiencies
Angel Wing / Slipped Wing
http://www.duckdvm.com/condition/angel-wing
https://blog.cacklehatchery.com/how-to-prevent-angel-wing-in-ducks-and-geese/
https://www.mailorderpoultry.com/angel-wing-in-ducks-symptoms-causes-cures/#
Choline Deficiency
http://www.duckdvm.com/condition/choline-deficiency
Niacin Deficiency / Vitamin B3 Deficiency
http://www.duckdvm.com/condition/niacin-deficiency
https://www.fresheggsdaily.com/2018/05/ducks-need-niacin-aka-ducks-love-peas.html
http://tiramarhomestead.com/2018/05/what-you-need-to-know-about-ducks-and-niacin/
https://metzerfarms.blogspot.com/2011/03/are-my-ducklings-leg-problems-due-to.html
Rickets
http://www.poultrydvm.com/condition/rickets
http://www.poultryhub.org/health/disease/types-of-disease/rickets-and-cage-layer-fatigue/
Thiamine Deficiency
http://www.duckdvm.com/condition/thiamin-deficiency
Vitamin A Deficiency
http://www.duckdvm.com/condition/vitamin-a-deficiency
Vitamin B6 Deficiency
http://www.duckdvm.com/condition/vitamin-B6-deficiency
Vitamin D Deficiency
http://www.duckdvm.com/condition/vitamin-d-deficiency
Parasites
Cecal Worms
https://poultrykeeper.com/digestive-system-problems/cecal-worms-or-heterakis-gallinarum/
Gapeworm
https://poultrykeeper.com/respiratory-problems/gapeworm/
Gizzard Worm
https://poultrykeeper.com/digestive-system-problems/gizzard-worm-amidostomum-anseris/
Large Roundworm
https://poultrykeeper.com/digestive-system-problems/large-roundworm-or-ascarida-galli/
Lice
https://poultrykeeper.com/external-problems/lice-on-chickens-and-poultry/
http://www.duckdvm.com/condition/lice
Mites
http://www.majesticwaterfowl.org/mmissue13.htm
http://www.duckdvm.com/condition/mites
Tapeworms
https://poultrykeeper.com/digestive-system-problems/tape-worms-or-cestodes/
Poisoning
Aflatoxin Poisoning
http://www.duckdvm.com/condition/aflatoxicosis
http://www.thepoultrysite.com/diseaseinfo/100/mycotoxicosis/
Botulism
https://www.msdvetmanual.com/poultry/botulism/overview-of-botulism-in-poultry
http://www.duckdvm.com/condition/botulism
https://www.beautyofbirds.com/botulism.html
Castor Bean Poisoning
https://ahdc.vet.cornell.edu/Sects/duck/health.cfm
Hardware Disease
https://www.fresheggsdaily.com/2015/07/preventing-hardware-disease-heavy-metal.html
Insecticides and Rodenticides
https://ahdc.vet.cornell.edu/Sects/duck/health.cfm
http://www.duckdvm.com/condition/rodenticide-toxicity
Rapeseed Meal Poisoning:
https://ahdc.vet.cornell.edu/Sects/duck/health.cfm
Zinc Poisoning
http://www.duckdvm.com/condition/zinc-poisoning
Miscellaneous Health Problems
Blocked Tear Duct
http://www.duckdvm.com/condition/blocked-tear-duct
Conjunctivitis / Pink Eye
http://www.duckdvm.com/condition/dry-eye
Curled Toes
https://sites.google.com/a/larsencreek.com/chicken-orthopedics/
http://www.farmingfriends.com/curled-toes-on-newly-hatched-ducklings/
Egg Binding
https://www.backyardchickens.com/articles/egg-binding-symptoms-treatment-and-prevention.66978/
http://www.duckdvm.com/condition/egg-binding
https://www.shagbarkbantams.com/egg-binding/
Egg Yolk Peritonitis
http://www.theveterinaryexpert.com/backyard-poultry/egg-yolk-peritonitis/
http://www.duckdvm.com/condition/egg-yolk-peritonitis
Foamy Eye
https://www.thecapecoop.com/foamy-eye-disease-ducks/
https://www.fresheggsdaily.com/2015/08/treating-foamy-eye-and-sinus-issues-in.html
Impacted Crop
http://www.majesticwaterfowl.org/mmissue46.htm
https://poultrykeeper.com/digestive-system-problems/impacted-crop/
Lameness
https://poultrykeeper.com/skeletal-and-muscular-disorders/lameness/
https://blog.cacklehatchery.com/what-causes-a-duck-to-limp-and-go-lame/
Prolapsed Penis/Vent
http://www.duckdvm.com/condition/penis-prolapse
http://www.majesticwaterfowl.org/mmissue28.htm
https://www.fresheggsdaily.com/2014/05/natural-treatment-of-vent-prolapse-in.html
http://www.duckdvm.com/condition/oviduct-prolapse
https://poultrykeeper.com/reproductive-system-problems/prolapsed-oviduct/
Sinusitis / Sinus Infection
https://www.fresheggsdaily.com/2015/08/treating-foamy-eye-and-sinus-issues-in.html
http://www.poultrydvm.com/condition/sinusitis
Tear Duct Infection
http://www.majesticwaterfowl.org/mmissue32.htm
Water Belly / Ascites
https://commonsensehome.com/ascites-in-ducks/
https://www.fresheggsdaily.com/2017/06/water-belly-or-ascites-in-backyard.html
Wet Feather
https://www.hobbyfarms.com/how-to-treat-wet-feather-in-ducks/
https://www.fresheggsdaily.com/2016/02/treating-and-preventing-wet-feather-in.html
http://www.duckdvm.com/condition/wet-feather
https://poultrykeeper.com/external-problems/wet-feather/
Wry Neck
https://www.fresheggsdaily.com/2014/04/preventing-and-treating-wry-neck-in.html
http://www.poultrydvm.com/condition/wry-neck