Worms

• Protozoan parasites

• Parasitic worms (helminth)

• Arthropod parasites

sexual reproduction in which either partner can act as female or male

characterizes a parasite whose development involves several host species.

One species: Monoxenous

sexual reproduction

developmental processes or asexual reproduction

Accumulates larvae and facilitates transmission to the definite host.

A disease which can be transmitted to humans from animals

Unnatural host, the parasite cannot establish patient infection, and cannot complete development.

Mebendazole, albendazole, and ivermectin single dose

• Nematoda (roundworms)

• Plathelminthes (flatworms)

DALY = Disability Adjusted Life Years

YLL = Years of Life Lost due to premature mortality

YLD = Years Lived with a Disability

(DALY = YLL + YLD)

Benzimidazoles: albendazole, mebendazole

• Ancylostoma duodentale

• Ancylostoma braziliense (cats/dogs)

• Ancylostoma ceylanicum (cats/dogs)

Wucheria bancrofti

Onchocerca volvulus

during the night: microfilariae move to surface vessels; coincides with feeding time of (mosquito) vectors

parasitic nematode worm that is transmitted by biting flies and mosquitoes, causing filariasis and related diseases.

E.g. Wucheria bancrofti & Brugia malayi

adult worms nest in the lymphatic vessels and disrupt the normal function of the lymphatics

Describes the condition of persistent (chronic) infection with adult worms, with effective immunity to larval stages of the same pathogen.

Mechanisms by which pathogens evade recognition or defense by the immune system

MDA treatment (albendazole (ALB) plus diethylcarbamazine (DEC), ALB plus ivermectin, or ALB alone) + highprotein, reduced-fat diet (success rate: 60%)

• invasive surgical procedures, such as sclerotherapy (sclerosis of lymphatic renal fistula) and nephrolympholysis (pyelolymphatic disconnection)

• steroid treatment against tropical pulmonary eosinophilia (cough/wheezing)

Vector control: Permethrin-impregnated bed nets Clean water, sewage management, proper garbage disposal, Insecticides

larvae of the blackfly vectors breed in fast flowing rivers

Worms that do not lay eggs, but give birth to microfilariae

The microfilaria is an early stage in the life cycle of certain parasitic nematodes in the family Onchocercidae.

• during the day: larger vessels, deep tissue blood

• during the night: surface vessels; coincides with feeding time of (mosquito) vectors

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filarial nematodes can carry a symbiotic partner, Wolbachia, which are intracellular alphaproteobacteria related to the pathogens Rickettsia and Erlichia

Antibiotics harm the development of the worm because it is in sybiosis with a bacterium.

Tetracycline treatment of infected animals results in blocking of nematode development, stunting of growth and elimination of fecundity

cycle repeats as pigs eat rats and rats eat larval stages containing cadaver leftovers from the slaughterhouse

• Adults cause a mild gastroenteritis

• Pathology arises with presence of larvae in muscle tissues and organs (fever, myositis)

• muscle fiber size increases in size, become edematous and develop a spindle form (nurse cell)

• => muscle pain

• Myocarditis/ respiratory failures=> death

• Within a year, symptoms can also fade and diseappear

nourish it as well as protect it from host immune responses

• mature Nurse cell is morphologically distinct from any other mammalian cell type

• can survive in the human host for up to 30 years

• polyzoic organisms (scolex, proglottids: head and many individual segments)

• can reach many meters (tapeworms)

• no mouth and no intestine

• infection (mostly) acquired via food

bovine tapeworm (D: Rinderfinnenbandwurm), 4-8m in lenght

hold-fast organ

cestodes use hooks, suckers, or both

• nutrients have to be taken up through the syncytial tegument

• Def. tegument: outer body covering of platyhelminth (dynamic structure with excretory/secretory/pore features)

• adult worms of Echinococcus measure only few mm (tiny tapeworms, 2-7 mm, max. 6 proglottids)

larval stage of a tapeworm

• unilocular, subspherical fluid-filled structure

• each hydatid is bounded by a thin continuous layer of parasite cells (germinal layer)

• hydatid cyst enlarges gradually, producing protoscolices and daughter cysts that fill the cyst interior

• early infection: completely asymptomatic or present with non-specific signs

• clinical presentation: >10 cm or when 70% of the organ volume has been taken up by the cyst (70% liver involvement)

• hypochondrial pain, a hepatic mass, and nausea and vomiting

• cystic rupture occurring spontaneously or infrequently after blunt abdominal trauma

• a rupture is a fatal complication = anaphylactic shock

• rupture can also cause ‘seeding’ of viable protoscolices in the peritoneum resulting in secondary hydatidosis

Albendazole to stop cyst growth, or surgery