Protozoan Disease: Definition, Symptoms, Examples, Treatment

Protozoan diseases are infections caused by protozoa. They are single-cell microscopic organisms, classified as a parasite. These diseases can affect both humans and animals which can lead to serious health issues. Protozoa affect the host through various routes which include contaminated water, food and insect bites.

This Story also Contains

1. What are Protozoa?
2. Differences Between Protozoa and Other Microorganisms
3. Protozoan Diseases and their Causative Agents and Transmission
4. Some Common Protozoan Diseases
5. Protozoan Disease Mechanisms
6. Signs and Symptoms of Protozoan Diseases
7. How Protozoan Diseases are Diagnosed?
8. How Protozoan Diseases are Treated?
9. Prevention and Control of Protozoan Diseases
10. Complications and Long-term Effects
11. MCQs on Protozoan Diseases
12. Frequently Asked Questions (FAQs)

Some common examples of protozoan diseases in humans include malaria, amoebiasis, giardiasis, trypanosomiasis, and leishmaniasis. Protozoal infections like coccidiosis and trichomoniasis also affect animals, impacting livestock health and productivity. Protozoan diseases are a major concern in the study of human health and diseases.

What are Protozoa?

Protozoa are tiny, unicellular eukaryotic cells that have the capability of self-propelled movement. They can be parasitic or free-living based on how they move. Their mode of nutrition is heterotrophic i.e. they feed on organic matter or other living organisms as parasites.

Differences Between Protozoa and Other Microorganisms

Protozoa are single-celled organisms that differ from other microbes like bacteria and viruses in structure, function, and life cycle. They often live as parasites and have complex survival strategies. Understanding these differences helps in identifying their role in disease. Some major difference between protozoan, bacteria and virus are discussed below:

Protozoan Diseases and their Causative Agents and Transmission

Protozoan diseases are caused by different protozoa and spread through water, food, or insect bites. These diseases are common in areas with poor hygiene and sanitation. It is important for both personal and public health. The following table enumerates a few prevalent protozoan illnesses, along with information on how they are caused and spread:

Some Common Protozoan Diseases

Protozoan diseases are caused by parasites that affect your health and organs in several ways. Some of the common lists of protozoan diseases along with their symptoms and causative agents are discussed below:

Malaria

It's caused by a plasmodium species and mainly by P. falciparum, P. vivax, P. ovale, and P. malariae. This is spread through bites of infected female Anopheles Mosquitoes. This is acquired by a parasite from the person who is infected by this mosquito. To prevent malaria you can use bed nets, indoor spraying and prophylactic medications in case of seriousness.

Amoebiasis

This protozoan disease is caused by Entamoeba histolytica, this disease is common in tropical areas and is transmitted via contaminated food or water containing protozoan cysts. Symptoms of this protozoan causative agent may vary from mild diarrhoea to severe dysentery and may lead to liver abscesses. Preventive steps against this protozoan disease include hand hygiene, drinking safe water, and ensuring proper sanitation.

Trypanosomiasis (Sleeping Sickness)

This protozoan disease is caused by Trypanosoma species, with T. brucei. This is responsible for causing African Trypanosomiasis and T. cruzi causing Chagas disease in South America. African Trypanosomiasis spreads through infected tsetse flies, while Chagas disease is transmitted by triatomine bugs ("kissing bugs"), through contaminated food, or blood transfusions. Symptoms of this disease vary from fever and headaches to severe neurological or cardiac issues. For preventive measures, you can include using insect repellents, improving living conditions, and avoiding contact with street vectors

Protozoan Diseases in Animals

Protozoan parasites also affect animals, Some common protozoan diseases in animals are discussed below:

1. Babesiosis: This is a disease caused by ticks which are infected with Babesia. It causes fever and anemia in animals like dogs and cattle.

2. Coccidiosis: Livestock and poultry get affected by this illness when they ingest Eimeria species. As an effect of this parasite, there will be diarrhoea and damage in the small intestine.

3. Theileriosis: Theileria species cause the infection in cattle, where ticks spread it out. Anaemia, fever, and enlargement of lymph nodes of the lymphatic system.

Protozoan Diseases in Plants

Some common protozoan disease in plants is discussed below:

• Clubroot Disease is most commonly caused by Plasmodiophora brassicae. It promotes large root formation and stunted plant growth in cruciferous vegetables.

• Phytomonas: A plant disease that reduces plant health and yields in crops like oil palm and coconut.

Protozoan Disease Mechanisms

Protozoa infect the host's body by entering through the digestive tract, skin, or blood. Once inside, they multiply and damage tissues or organs. Some may avoid the immune system, making infections worse. Each species uses a unique mechanism to cause disease. Protozoa may be the causative agents of disease via numerous different mechanisms:

• Invasion: Protozoa go into host cells and tissues, in which they propagate and therefore disrupt normal body activities.

• Immunoevasion: Protozoa have techniques (antigenic variation) permitting them to hide from recognition by the host's immune system.

• Tissue destruction: Protozoa generate damage in 2 ways: direct cell death of host tissues or induction of inflammatory reactions.

Protozoan Diseases and Their Transmission

Person-to-Person Transmission

• Direct Contact: trichomoniasis is transmitted through intimate contact.

Indirect Transmission

• Contaminated Food And Water: Protozoa such as Entamoeba histolytica and Giardia lamblia are transferred from an infected person, through ingestion of contaminated food and or water.

• Fomites: Some protozoa can survive on surfaces and be transmitted through contact with contaminated objects.

Vector-Borne

• Insects: Protozoa like Plasmodium spp. (malaria) and Trypanosoma spp. (Chagas disease and African sleeping sickness) are transmitted by insect vectors like mosquitoes and tsetse flies.

Signs and Symptoms of Protozoan Diseases

Symptoms can vary based on the disease and the affected part of the body. Common signs include fever, diarrhea, fatigue, and weight loss. Some show severe symptoms like organ damage. Early detection can reduce health risks. Some of the common signs and symptoms of protozoan diseases are discussed below:

General Symptoms

• Fever is common in diseases such as malaria.

• Diarrhoea may be seen in diseases such as amoebic dysentery and giardiasis.

• Fatigue

• Abdominal pain is common in infections.

Specific Symptoms

• Malaria: Fever and shaking chills, anaemia, fatigue, and an enlarged spleen.

• Amoebiasis: diarrhoea with mucus and blood, stomach pain, and weight loss.

• Giardiasis: Watery faeces, gas, and malnutrition.

Risk Factors of Protozoan Disease

Acquiring protozoan infections is more likely if you have:

• Poor sanitation

• Drinking infected water

• Access to medical care

• Weakened immune systems

• Travel to places with contagious diseases

How Protozoan Diseases are Diagnosed?

Diagnosis usually involves lab tests like blood smear, stool test, or antigen detection. Identifying the parasite early helps in better treatment. Microscopes and modern diagnostic tools are used. Accurate diagnosis is important for controlling the disease. Diagnosing protozoan disease typically involves using:

• Microscopy: Microscopy of stool, blood, or tissue specimens to find the protozoan.

• Serological Testing: Identification of specific antigens or antibodies in the blood.

• Molecular Methods: For detecting protozoan genetic material, such as PCR and other DNA-based methods

How Protozoan Diseases are Treated?

Protozoan diseases are treated using antiparasitic drugs. The type of medicine depends on the species of protozoa involved. In severe cases, hospital care may be needed. Timely treatment can prevent serious complications. Treating protozoan infection includes:

• Maintain fluids and nutrients, and treat the symptoms with supportive care.

• Antiparasitic medications are used to treat amoebic dysentery and chloroquine for malaria.

• In extreme cases, removing affected body parts could result in a surgical operation.

Prevention and Control of Protozoan Diseases

Parasitic protozoans are significantly larger and more complicated pathogens than viruses or bacteria. They use a variety of mechanisms to evade the host's immune system. It is difficult to develop vaccination for protozoan diseases. As a result, preventing protozoan infection is more convenient than treating it. The strategies for preventing protozoan infection include:

• Sanitation: Maintaining clean water and food practices.

• Vector Control: Reducing insect vectors with the use of insecticides, bed nets, and repellents

• Personal Protection: Avoid infected water and food, have safe sex, and wear protective clothing.

Complications and Long-term Effects

If left untreated, it can lead to serious health problems. They may damage organs, cause long-lasting weakness, or even death. Some diseases may return or become chronic. Prevention and early treatment are key to avoiding such outcomes.

Immediate Effects

• Significant Anaemia: Especially in malaria, it leads to fatigue and pallor.

• Organ Damage: Protozoa, such as species in Malaria, may result in impaired organ function, including liver and splenic damage.

• Shock: Severe infections can result in a systemic inflammatory response and shock.

Chronic Effects

• Chronic disease syndromes: Prolonged symptoms in the form of chronic fatigue or gastrointestinal morbidity.

• Neurological Failure: Long-term effects that can develop following cerebral malaria infections or associated with immuno-compromised patients.

MCQs on Protozoan Diseases

Q1. Which one of the following diseases is caused by a protozoan?

1. Malaria

2. Amoebiasis

3. Both (a) and (b)

4. All of the above

Correct answer: 4) All of the above

Explanation:

As we have already studied in Protozoan Disease -

Malaria and Amoebiasis is a type of protozoan disease. Malaria is caused by a parasite - Plasmodium and transmitted into the human body by the bite of a female mosquito called Anopheles. Its symptoms include malarial fever, restlessness, less appetite and muscular pain. Amoebiasis is caused by Entamoeba histolytica. It can be caused by the fecal-oral route or sexual transmission. Its symptoms include stools with blood and abdominal pain

Hence, the correct option is 4) All of the above.

Q2. Which one of the following cannot be used for preparation of vaccines against plague?

1. Formalin-inactivated suspensions of virulent bacteria

2. Avirulent live bacteria

3. Synthetic capsular polysaccharide material

4. Heat-killed suspensions of virulent bacteria

Correct answer: 3) Synthetic capsular polysaccharide material

Explanation:

Plague is an infectious disease caused by the bacterium Yersinia pestis. Inactivated bacteria have been used since 1890 but have been less effective against pneumonic plague, so live attenuated and recombinant protein vaccines have recently been developed to prevent the disease. Synthetic capsular polysaccharide vaccine for the treatment of pneumonia and meningitis. Therefore, synthetic capsular polysaccharide materials cannot be used in the preparation of vaccines against harmful organisms.

Hence, the correct answer is option 3) synthetic capsular polysaccharide material.

Q3. Which one of the following diseases is not caused due to contamination of water?

1. Hepatitis-B

2. Jaundice

3. Cholera

4. Typhoid

Correct answer: 1) Hepatitis-B

Explanation:

Hepatitis B is spread through body fluids like blood, sperm, sputum, mucus, and vaginal fluids. It can be transmitted via direct contact with infected fluids, such as through unprotected sexual contact, sharing needles, or from an infected mother to her baby during childbirth. The virus can also be transmitted through exposure to contaminated blood products or medical equipment that hasn't been properly sterilized. In some cases, the virus can be spread through sharing personal items, like razors or toothbrushes, that may have come in contact with infected blood. Hepatitis B can lead to chronic liver disease, liver cancer, or cirrhosis if left untreated.

Hence, the correct answer is the option 1) Hepatitis-B.

Also Read:

• MCQs on Protozoan Diseases

• Immunology

• Antibodies

Frequently Asked Questions (FAQs)

Q1. What are the common protozoan diseases?
Some of the common protozoan diseases include malaria, amoebiasis, giardiasis, leishmaniasis, and sleeping sickness.

Q2. Is dengue a protozoan disease?
No, dengue is a viral disease caused by the dengue virus, not by protozoa.

Q3. What are the 5 plant diseases caused by protozoa?
Examples include bunchy top of papaya, little leaf of brinjal, grasserie of silkworm, and spike disease of sandalwood.

Q4. What are a few examples of protozoa?
A few examples of protozoa are Plasmodium, Entamoeba, Giardia, and Trypanosoma.

Q5. Is dysentery caused by protozoa?
Yes, amoebic dysentery is caused by the protozoan Entamoeba histolytica.