Parasites

A parasite is an organism that lives in or on a host organism and gets its food from or at the expense of its host

• strongly specialized on their host

• co-evolutionary evolved with their hosts

• survive in extreme habitats

• chronically infects the host

• large endemic/areas high prevelance

• high productivity rates

• Large Body size

• Hermaphroditism

• Protozoan Parasites, single cell eukaryotic organisms that infect hosts, often causing Diseases like malaria and sleeping sickness

• Parastic Worms (hemlinths) Multicellular intevertebrates, including roundworms and flatworms that live in or on their host, often disrupting body function

• Arthropod parasites Invertebrates with exosceleton, such as ticke, mites and lice that feed on the hosts and can transmit disease

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• Monoxenous: Inside a Host

  • (Ascaris lumbricoides(worm), Trichus suis)

• Diheteroxenous: Intermediate Host-> Final Host

  • Carunculus medinensis

• Trihetereoxenous: First Intermediate Host -> Second Intermediate Host -> Finale Host

  • Schistocephalus solidus (Tapeworm of water birds)

• Dracunculus = little Dragon, a roundworm (nematode)

• female worms are 70-120 cm

• produce enema, blister and ulcers

• secondary infections & abscess formation

• tetanus, septic arthritis or systemic sepsis

• symptoms: fever, nausea and vomiting to permanent disability

• no effecitve anti parasitic or vaccine/medical prophylaxis

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• 1a and 1 b copepods infected with larvae of Drancunculus inside Water or undercooked fish or frogs are consumed by human

• swollowed copepods die inside the stomach and the larvae are released into the body, they penetrate the wall of the stomach and intesting and enter the abdominal cavity. There the larvae mature into Adult worms, which then mate

• After mating the male worms die and the female worms move through tisses under the skin usually to the legs or feet. About a year after people become infected the worms come to the surface of the skin causing sever blisters, casing a burning sensation, the blisters eventually break open

• People usually try to releave the pain by putting their legs into water where the worms release larvea into the water

• the larvea are ingested by copepod

• inside the copepod the larvea change into different forms and become able to cause infection, when they become consumed again the cycle is completed

• Mostly in the Sahel belt of Africa, limited to tropical or subtropical areas

• affects the poorest of the poor

• Almost eradicated, from over a million cases in chad in 1985 to 14 cases in 2023

• Angola, Cameroon, Chad, Ethiopia, Mali and South Sudan

• Infections in non human animal species are difficult

• Numbers increased in animals(cats/dogs)

• Water filtration devices -> removing copepods from drinking water

• Water treatment with larvicides -> vector control

• Containment of human and animal cases(reporting) -> prevent transmission

• cash rewards for reporting suspected cases of GWD in animals and humans

• Worm like parasites

  • Round and flatworms

• 342 helminth species are described to be associated with humans

• are multicellular animals, highly adapted to vertebrate hosts

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1. embryonation (eggs)

2. moulting (L2 -> L3/L4)

3. sexual reproduction/maturation (adult worm)

4. Example here Trichuris suis (pig whipworm)

Trichuris trichiura(whipworm)

• 3-5cm long, lives in the large intestine, infects large intestine

  
  

• Monoxenous lifecycle, eggs hetch into larvea in small intestine and mature there, eggs passed through fesces into soil, and get ingested

• Bacteria triggered egg hatching in the small intestine

• L1 larvea penetrate gut epithellal cells

• intra-epthelial larvae in gut cells (L1 and L2)

• L3 and L4 larvae extend into the gut lumen

• Adult worms start intracellular infection into the large intestine

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Ascaris lumbricoides(small intenstinal roundworm)

• 15-35 cm long, lives in small intestine infects liver, lungs and small intestine, monoexenous lifecycle

• 1. Adults life in small intestine

• 2. eggs released through fesces into the wild

• 3. embryogenated egg with L3 larvae

• 4 Ingestion

• 5 hatched larvae enter circulation and migrate to lungs

• 6 larvae are coughed ip and swallowed, re-entering the gastrointestinal tract. Maturation proceeds in the small intestine.

• Eggs hatch realeasing L3 larvae

• larvae penetrate the epthelim of the large intestine and migrate to liver

• migration of l3 larvae through pulmonary tissue

• larvae are coughed up and swollowed

• adult worms dwell in the lumen of the small intestine

• associated with poverty

• lack of proper sanitary infrastructure and poor socio-economic conditions

• environmental and behavioural features

• hosts genetics and immunity

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• often asymptomatic

• gut pathology caused by large number of small worms

• feed on intestine fluid (not blood)

• accute or chronic large intestinal diarrhea

• abdominal pain, rectal prolapse and possibly growth retardation

• impaired coginitve development

• Anthelminthic Therapy

  • Mebendazole, albendazole, ivermectin

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• community-wide MDA to reduce infection intensity in communities and interrupt transimission

• regular, periodic treatment to an entire population in a geographic are

• all egilible people infected or not receive a treatment

• school-based delivery system

• Ancylostoma duodenale

  • greater mdeical veterinary importance due to higher distribution, prevalencae and zoonotic species

• Necator americanus

• depend on host haemoglobin and serum proteins

• adult worms blood suckers in the small intestine

• feed on villus rupturing it with teeth

• Causing Anemia

• sunted growith and iron deficiency and cognitive impairment in children

ancylostoma, necator

Both species attach to the intestinal wall and feed on blood, potentially causing anemia.

1. Zoonotic Hookworm Infections (e.g., Ancylostoma braziliense, Ancylostoma caninum):

   • Transmission: Zoonotic hookworms are typically transmitted to humans through skin penetration by larvae from contaminated soil (often from pets, like dogs or cats).

   • Pathology: These infections often result in cutaneous larva migrans (creeping eruption), where the larvae move under the skin, causing localized itching, inflammation, and a serpentine rash. They don’t mature into adults in humans, but the infection can lead to discomfort and sometimes systemic symptoms if larvae migrate deeper.

2. Human-Specific Hookworm Infections (e.g., Ancylostoma duodenale, Necator americanus):

   • Transmission: These hookworms are transmitted through larvae ingestion or skin penetration, typically via contaminated soil. The larvae mature into adults in the small intestine and suck blood.

   • Pathology: These infections cause more severe systemic effects like anemia (due to blood loss), malnutrition, and abdominal pain. Chronic infections can result in growth retardation in children and more serious gastrointestinal complications.

• mmagraphical thorugh breastfeeding

• oral

• skin penetration

• not by their eggs

• - A. duodenale = male 8-12 mm,

  female 10-15 mm

  - N. americanus males are 5-9 mm

  long, females 9-11 mm.

• The anterior region differentiate Ancylostoma has cutting teeth while Necator has motuh parts with cutting plates

• adult worms can be differentiated based on the morphology of the buccal capsule and the adult male coulatory bursa

• transmission through human faeces,

  • Cutaneous rout -> penetration of the skin by infective filariform larva

  • Oral route -> ingestion of L3 larca present in the soil

  • Transmammary transmission -> Breast feeding by mothers to infants

• withing 24-48h, L1 larvae can develop into L3 under favourable environmental conditions

• L3 migrate inside human body

• L3 enters lymphatics to venous circulation

• migrates to bronchi

• MDA (single-dose) albendazole or mebendazole but not very effective

• Human Hookworm Vaccine Initiative (targeting surface antigens at larval stages) or gut antigens (adults)

• Nematodes that inhabita tissues or body cavities but never the intestine

• long, filiform worms

• inhabit lymphatics or connective tissues

• do not lay eggs but give birth to microfilariae

• transmitted by bloodsucking arthropods(vector-borne disease)

• Infected moscito transmitts mosquito

• larvae migrates to lymphic system(nodes and vessels) developing into threat like adult worms

• female worms release embryonic offspring)(microflariea)

• uptake of microfiliariae by vector

• (L1 to L3)

• w.bancrofti 22-2:00 is active in the bigger vessels, during night time more the surface vessels coincides with mosicto feeding time

1. periodicity in which theycirculate in the blood predominately at certain times of the day must be known

2. prepare thick and thin blood films

3. Giemsa, Wright-Giemsa, and Delafield’s hematoxylin

4. Transmission factors

   1. population prevelance, mf density in blood, moscito density, environment, vector exposure

2021: 882.5 million people in 44 countries (40%India 30% Africa)

• painful and profoundly disfiguring manifestiaton of diseases. Lymphodema, elephantiasis and scrotal sweling

• tropical pulmonary eosinophilia (can be mistaken for asthma)

• Immune evasion srategies

  • mechanical protection, mobility, retreat, antigen change, antigen masking, detoxifying enzymes, immunomodulation

• MDA treatment (albendazole diethylcabamazine)

• surgical procedures

• steroids

• vector control

vessels.

fits!

-scleoratl growth

• Immune response

  • adequate

    • resistent potenntially immune (mf-negative)

  • hyporeactive (cellular repression)

    • low pathology (mf-positive)

  • hyperreactive

    • extreme pathology (mf-negative)

• mosquitoes (W. bancrofti and Brugia spp.)

  biting midges (M. ozzardi, M. perstans, and M. streptocerca)

  black flies (M. ozzardi and O. volvulus)

  deer flies (L. loa).

• can carry symbiotic partner, Wolbachia, which are intracellular aphaproteobacteria

• Tetracycline bocks nematode development

• female Onchocerca cannot produce viable microfilariae