Filariasis, ascariasis, amoebiasis, ringworm and disease control
Worms (Wuchereria, Ascaris), a protozoan (Entamoeba) and fungi cause these diseases. Personal and public hygiene, vector control, vaccines and drugs keep them in check.
Four diseases at a glance
| Disease | Pathogen | Where it lives | How it spreads | Symptoms |
|---|---|---|---|---|
| Filariasis (elephantiasis) | Wuchereria bancrofti, W. malayi (filarial worms) | Lymphatic vessels, usually of the lower limbs | Bite of female mosquitoes (extra, not in textbook: mainly Culex) | Slow, chronic inflammation for many years; swollen limbs; genital organs may be deformed |
| Ascariasis | Ascaris (roundworm) | Intestine | Eggs pass out in faeces and contaminate soil, water, vegetables, fruits | Internal bleeding, muscular pain, fever, anaemia, blockage of the intestine |
| Amoebiasis (amoebic dysentery) | Entamoeba histolytica (protozoan) | Large intestine | Food and water contaminated with faeces; houseflies carry the parasite to food | Constipation, abdominal pain and cramps, stools with excess mucus and blood clots |
| Ringworm | Microsporum, Trichophyton, Epidermophyton (fungi) | Skin, nails, scalp | Soil; sharing towels, clothes or combs of infected people | Dry, scaly lesions with intense itching; common in moist skin folds like the groin and between toes |
Mechanical carrier vs vector
Control of these diseases
- Personal hygiene: keep the body clean; drink clean water; eat clean food, and wash vegetables and fruits.
- Public hygiene: proper disposal of waste and excreta; regular cleaning and disinfection of water tanks, pools and cesspools; hygiene in public catering.
- Air-borne diseases (pneumonia, common cold): avoid close contact with infected people and their belongings.
- Vector-borne diseases (malaria, filariasis, dengue, chikungunya): remove breeding places, use nets and mesh, Gambusia fish, insecticides.
- Vaccines and immunisation have eradicated smallpox and largely controlled polio, diphtheria, pneumonia and tetanus.
- Antibiotics and other drugs treat many infectious diseases.
Activity: spotting disease-causing organisms
Look at each slide, model, specimen or image. Write the name, two identifying features and the symptoms of the disease it causes.
- 1Ascaris (specimen): long, cylindrical, unsegmented worm with pointed ends; female larger with a straight tail, male smaller with a curved tail. Comment: causes ascariasis, with internal bleeding, anaemia and intestinal blockage.
- 2Entamoeba histolytica (slide): irregular shape with pseudopodia and a single nucleus; may show swallowed RBCs. Comment: causes amoebiasis, with abdominal cramps and stools with mucus and blood.
- 3Plasmodium (blood smear slide): small ring-shaped stages inside red blood cells. Comment: causes malaria, with chills and high fever every 3 to 4 days.
- 4Ringworm fungus such as Trichophyton (slide or image): branched hyphae with spores; on skin, a round, red, scaly, itchy patch. Comment: causes ringworm of skin, nails or scalp.
- 5★Record your answers in a table: organism, group (worm, protozoan, fungus), disease, symptoms, and one way to prevent it.
★ key step
India's school deworming days give children tablets against roundworms like Ascaris, which cause anaemia and poor growth. Washing hands with soap, wearing slippers outside, and eating washed vegetables keep the worms from coming back.
2 marks: “How do houseflies help spread amoebiasis? Write two symptoms of the disease.” They act as mechanical carriers, transferring Entamoeba histolytica from faeces to food. Symptoms: abdominal pain and cramps; stools with excess mucus and blood clots.
3 marks: “Name the pathogens of filariasis and ringworm. Describe one symptom and one mode of spread of each.” Filariasis: Wuchereria bancrofti, W. malayi; chronic inflammation of lymphatic vessels of lower limbs; mosquito bite. Ringworm: Microsporum, Trichophyton, Epidermophyton; dry, scaly itchy lesions; shared towels or combs, soil.
3 marks: “List the measures of personal and public hygiene that help prevent infectious diseases.” Personal: clean body, clean water and food, washed fruits and vegetables. Public: disposal of waste and excreta, cleaning and disinfecting water tanks and pools, hygiene in public catering; plus vector control and vaccination.
Wuchereria swells the legs, Ascaris blocks the gut, Entamoeba brings blood in stools, ringworm loves sweaty folds.