Protozoan Disease: Definition, Symptoms, Examples, Treatment

Protozoan infections, or protozoan diseases, are what you call infections that are brought on by protozoa— unicellular eukaryotic organisms. When an infection affects a human body's organs and systems, the symptoms vary depending on the severity of the infection. They vary from mild conditions to life-threatening situations. In tropical and subtropical regions, these infections draw attention as major concerns for public health due to the high mortality rates caused by them, along with their high morbidity rates. Effective treatment and prevention strategies can be established by knowing what mechanisms lead to these infections and their causes and symptoms.

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This Story also Contains

1. What are Protozoa?
2. Differences Between Protozoa and Other Microorganisms
3. Protozoan Diseases in Humans: Causative Agents and Transmission
4. Malaria
5. Trypanosomiasis
6. Leishmaniasis
7. Protozoan Diseases in Animals
8. Protozoan Diseases in Plants
9. Protozoa's mechanisms of disease
10. How Protozoa Are Transmitted
11. Signs And Symptoms of Protozoan Diseases
12. Risk Factors
13. How Protozoan Diseases are Diagnosed
14. How Protozoan Diseases are Treated
15. Prevention and Control of Protozoan Diseases
16. Complications and Long-term Effects

What are Protozoa?

Protozoa are tiny, unicellular eukaryotic organisms that have the capability of self-propelled movement. They can be parasitic or free-living based on how they move.

Nutrition: Heterotrophic; feeds on organic matter or other living organisms as parasites.

Differences Between Protozoa and Other Microorganisms

Bacteria: Unlike the more basic prokaryotic bacteria, protozoa are eukaryotic and have nuclei.

Viruses: Viruses need to hijack the machinery of another cell to reproduce. Protozoa: All of these are living cells. These single-celled creatures can reproduce independently of each other.

Protozoan Diseases in Humans: Causative Agents and Transmission

The following table enumerates a few prevalent protozoan illnesses, along with information on how they are caused and spread:

Certain parasites can be the basis of many diseases affecting humans, animals and plants. They include, but are not limited to; leishmaniasis, amoebiasis, trypanosomiasis, malaria and more. It is a fact that the above-named diseases are most prevalent among people.

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Plasmodium species cause malaria, which is spread by Anopheles mosquitoes and causes fever, chills, and anaemia. Tsetse flies transmit trypanosomiasis, commonly known as sleeping sickness, which causes fever, headaches, and ultimately neurological problems. It is caused by Trypanosoma species.

Abdominal pain and severe diarrhoea are symptoms of amoebiasis, which is caused by Entamoeba histolytica and spreads through contaminated food and water. Leishmaniasis, caused by Leishmania species and transmitted by sandflies, results in skin sores, fever, and spleen enlargement.

Malaria

Prevalent species of protozoan parasites that cause the most widespread forms of human malaria include P. falciparum, P. vivax, P. ovale, and P. malaria.

This condition mainly affects humans through mosquito bites, here, anopheles female mosquitoes are the main culprits because they carry this virus within themselves. It passes to people when they are bitten by female Anopheles mosquitoes who have been infected with this parasite by biting other infected people before biting them (CDC).

Prevention: Three preventive strategies for malaria are; using treated bed nets, indoor spraying, and taking drugs to prevent this disease.

Trypanosomiasis

Trypanosomiasis, or sleeping sickness, is caused by microscopic parasites called Trypanosoma spp. In Africa, it is caused by Trypanosoma brucei, while in South America, Chagas disease is caused by Trypanosoma cruzi.

Transmission: Chagas’ disease spreads through contaminated food, blood transfusion or mother-child transmission. On the other hand, triatomine bugs, also known as ‘kissing bugs', transmit African Trypanosomiasis when they feed on people after being infected with trypanosomes through the bite of an infected tsetse fly.

African Trypanosomiasis includes fever, headache, joint pain and pruritus (itching). Later, the disease affects the central nervous system, leading to neurological manifestations such as altered sleep-wake cycles or even death in severe cases. In addition to causing enduring cardiac or gastrointestinal disturbances, Chagas disease may also present with fever, discomfort, myalgia, and oedema, especially at the infection site.

Treatment and Prevention: To prevent African trypanosomiasis, suggested steps include using insect repellent, creating better living conditions, and avoiding contact with vector insects. Antiparasitic medications can be used for treatment in cases where necessary.

Amoebiasis

Cause: Amoebiasis results from infection with Entamoeba histolytica; a protozoan organism that thrives in tropical climates and is often found near bodies of water contaminated by sewage systems.

Transmission: This disease spreads person-to-person via ingesting food or drink contaminated with faecal matter containing even microscopic-sized protozoan cysts can lead to illness. Signs may range according to severity, from mild diarrhoea to dysentery. Sometimes liver becomes infected, causing amoebic liver abscess.

Prevention and Treatment:

• Practise good personal hygiene, such as hand washing before eating and after using the toilet.
• Drink -safe water
• Ensure proper sanitation by constructing toilets that do not leak into water sources.
• Taking medications will cure most cases of invasive diseases.

Leishmaniasis

Leishmaniasis is caused by protozoan parasites of the genus Leishmania. The different forms of the disease are referred to as cutaneous, mucocutaneous, and visceral leishmaniasis. These categories depend on the parasite species and the body parts that are affected.

Transmission: The disease is transmitted through the bite of infected female sandflies.

Symptoms:

• Cutaneous Leishmaniasis causes skin sores that may become ulcers.

• Mucocutaneous Leishmaniasis affects the mucous membranes of the nose, mouth and throat, causing sores and destroying mucous tissue.

• Visceral Leishmaniasis (Kala-azar) affects internal organs, such as the spleen, liver, and bone marrow, causing fever, weight loss, anaemia, and swelling of the liver and spleen.

Protozoan Diseases in Animals

Protozoan parasites also affect animals, where they cause diseases such as:

1. Babesiosis: This is a disease caused by ticks which are infected with Babesia. It causes fever and anaemia 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 intestinal damage.

3. Theileriosis: Theileria species cause the infection in cattle, where ticks spread it out. Anaemia, fever, and enlargement of lymph nodes are some symptoms caused by this protozoan disease.

Protozoan Diseases in Plants

• 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.

Protozoa's mechanisms of 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.

Toxin Generation

Certain protozoa generate toxins that result in the symptoms of the disease. As an example, Entamoeba histolytica secretes enzymes that begin the degradation of tissue in a host, contributing to ulcers of the intestines.

How Protozoa Are Transmitted

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

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

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

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

Treating protozoan infection includes:

• Maintain fluids and nutrition, 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 vaccines 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

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.

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