COMMON DISEASES IN HUMANS
Introduction
- Various pathogens cause diseases in humans.
- Pathogens can enter the body, multiply, and disrupt normal functions.
Bacterial Diseases
Salmonella Typhi and Typhoid Fever
- Pathogenic bacterium causing typhoid fever.
- Transmitted through contaminated food and water.
- Symptoms include sustained high fever, weakness, stomach pain, etc.
- Mary Mallon, a typhoid carrier, is an example.
Streptococcus Pneumoniae and Haemophilus Influenzae
- Responsible for pneumonia in humans.
- Infection of lung alveoli, leading to respiratory problems.
- Transmission through infected persons and shared items.
Other Bacterial Diseases
- Dysentery, plague, diphtheria, etc., are bacterial diseases in humans.
Viral Diseases
Rhinoviruses and Common Cold
- Rhinoviruses cause the common cold.
- Symptoms include nasal congestion, sore throat, cough, and more.
- Transmitted through respiratory droplets and contaminated objects.
Protozoan Diseases
Malaria and Plasmodium
- Plasmodium causes malaria.
- Different species lead to various types of malaria.
- Severe cases can be fatal.
- Transmission through infected mosquitoes.
Amoebiasis and Entamoeba Histolytica
- Protozoan parasite causing amoebiasis.
- Symptoms include constipation, abdominal pain, and more.
- Transmission through houseflies and contaminated water/food.
Helminthic Diseases
Ascaris and Ascariasis
- Ascaris is an intestinal parasite causing ascariasis.
- Symptoms include internal bleeding, pain, fever, anemia, and blockage.
- Transmission through contaminated water and food.
Wuchereria and Elephantiasis
- Filarial worms causing chronic inflammation in lymphatic vessels.
- Can lead to deformities.
- Transmitted through mosquito bites.
Fungal Diseases
Ringworms
- Microsporum, Trichophyton, and Epidermophyton fungi cause ringworms.
- Symptoms include dry, scaly lesions and intense itching.
- Transmission through soil and shared items.
Preventive and Control Measures
- Personal hygiene, clean water and food, and public hygiene are crucial.
- Hygiene practices vary based on the mode of disease transmission.
- Vector control, vaccines, and antibiotics are vital tools in disease control.
Advances in Disease Control
- Vaccines, immunization, and biotechnology have improved disease control.
- Smallpox eradicated through vaccination.
- Other diseases controlled with vaccines and antibiotics.
- Biotechnology offers safer vaccines and treatments.
Bacterial diseases
| Pathogen Name | Mode of Transmission | Symptoms | Prevention Measures |
|---|---|---|---|
| Salmonella Typhi | Contaminated food and water | High fever, weakness, stomach pain, constipation, headache, loss of appetite. Intestinal perforation and death in severe cases. | Personal and public hygiene, clean water, and proper food handling. |
| Streptococcus Pneumoniae | Inhalation of respiratory droplets, shared items | Fever, chills, cough, headache, gray to bluish lips and fingernails in severe cases. | Avoid close contact with infected individuals, vaccination. |
| Haemophilus Influenzae | Inhalation of respiratory droplets, shared items | Similar to pneumonia symptoms. | Avoid close contact with infected individuals, vaccination. |
| Other Bacterial Diseases | Various modes of transmission (not specified) | Vary depending on the disease. | Personal and public hygiene, vaccination where available. |
Viral diseases
| Pathogen Name | Mode of Transmission | Symptoms | Prevention Measures |
|---|---|---|---|
| Rhinoviruses | Inhalation of respiratory droplets, contact with contaminated objects | Nasal congestion, sore throat, cough, headache, tiredness. Lasts 3-7 days. | Avoid close contact with infected individuals, practice good respiratory hygiene, and maintain personal hygiene. |
| Other Viral Diseases | Various modes of transmission (not specified) | Vary depending on the disease. | Avoid close contact with infected individuals, vaccination where available. |
Protozoan diseases
| Pathogen Name | Mode of Transmission | Symptoms | Prevention Measures |
|---|---|---|---|
| Plasmodium | Through the bite of an infected female Anopheles mosquito | Malaria symptoms include recurring high fever, chills, and anemia. Fatal in severe cases. | Vector control (mosquitoes), use of mosquito nets, and personal protection. |
| Entamoeba Histolytica | Transmission through houseflies and contaminated water/food | Symptoms include constipation, abdominal pain, mucous and blood in stools. | Personal and public hygiene, clean water, and proper food handling. |
Worm diseases
| Pathogen Name | Mode of Transmission | Symptoms | Prevention Measures |
|---|---|---|---|
| Ascaris | Transmission through contaminated water and food | Internal bleeding, muscular pain, fever, anemia, intestinal blockage | Personal and public hygiene, clean water, and proper food handling. |
| Wuchereria | Transmitted through mosquito bites | Chronic inflammation in lymphatic vessels, deformities | Vector control (mosquitoes), personal protection, and use of bed nets. |
Fungal Diseases
| Pathogen Name | Mode of Transmission | Symptoms | Prevention Measures |
|---|---|---|---|
| Microsporum, Trichophyton, and Epidermophyton | Transmission through contact with contaminated objects or soil | Dry, scaly lesions on skin, nails, and scalp, accompanied by intense itching | Personal and public hygiene, avoiding sharing personal items, and maintaining cleanliness. |
The life cycle of Plasmodium
Entry into the Human Host:
- Plasmodium enters the human body as sporozoites. These sporozoites are the infectious form of the parasite.
- This entry typically occurs when an infected female Anopheles mosquito bites a human and injects the sporozoites into the person’s bloodstream.
Liver Stage:
- Once inside the human host, the sporozoites travel to the liver.
- They invade liver cells and begin to multiply, forming thousands of new parasites known as merozoites.
Blood Stage:
- The merozoites are released from the infected liver cells into the bloodstream.
- In the bloodstream, the merozoites invade red blood cells (RBCs).
Multiplication in Red Blood Cells:
- Inside the RBCs, the merozoites undergo a cycle of multiplication.
- They multiply rapidly, leading to the rupture of the infected RBCs.
Release of Toxins and Symptoms:
- The rupture of infected RBCs releases merozoites and a toxic substance called haemozoin into the bloodstream.
- The release of haemozoin is responsible for the recurrent symptoms of malaria, such as chills, high fever, and other flu-like symptoms.
Continuation of the Cycle:
- Some of the merozoites go on to infect new RBCs, continuing the cycle of multiplication and rupture.
Transmission Back to the Mosquito:
- When an infected person is bitten by a female Anopheles mosquito, the mosquito ingests the merozoites along with the person’s blood.
Mosquito Host:
- Inside the mosquito, the merozoites transform into sporozoites.
Further Development in the Mosquito:
- The sporozoites multiply within the mosquito’s body and eventually migrate to its salivary glands.
Transmission to Another Human:
- When the infected mosquito bites another human, it injects the sporozoites from its salivary glands into the new host’s bloodstream, restarting the cycle in a different human.
