Protozoal infections are parasitic diseases caused by those organisms that were previously placed in the realm of Protozoa within biological systematics. Significant examples of causative organisms of protozoan diseases include Entamoeba histolytica as the causative agent of amoebic dysentery, Plasmodium falciparum as the causative agent of malaria tropica, Giardia lamblia, which about ten percent of the world’s population carries in their intestines, or Trypanosoma brucei, which causes African sleeping sickness via the infected tsetse fly.
What is a protozoan infection?
A protozoal infection is that pathological condition that results from invasion of the body by pathogenic protozoa. Protozoonosis, as protozoal infection is also called, is a disease caused by a number of protozoa, or single-celled organisms. Thus, protozoal infections are also a subset of parasitoses; consequently, all those diseases that can be caused by parasites. The term infection is justified in this context by the fact that the typifying sequence of invasion, multiplication and reaction is present. Due to the constant progress of knowledge in biology, the systematic categorization in a taxon Protozoa is outdated. The phylogenetic relations of the groups summarized as protozoa showed to be far more complex than could originally be assumed from the morphological consideration of the “primordial animals”. A definition of protozoa based on biological systematics is thus no longer possible. The retention of terms such as protozoology or protozoan infection serves only practical considerations. This is because the common systematic denominator of organisms commonly referred to as protozoa goes back to the biological domain of eukaryotes.
Causes
The causes of protozoan infection in humans are disease-causing microorganisms that are parasites that rely on him as a host organism. Trigger of the protozoonoses is based thereby on a variety of different organisms. The International Classification of Diseases ICD-10 published by the World Health Organization (WHO) lists diseases caused by protozoa in sections A06 to A07 and B50 to B64. It should be noted here that with regard to protozoal diseases, the ICD-10 bases its systematics on the overview of the disease pattern caused. Generally speaking, infection with protozoa occurs via ingestion of contaminated food, water, contaminated drinking or bathing water or via the intermediate host route. The causative organisms are therefore included in the following list as examples where appropriate, “spec.” denoting multiple or unknown species of a genus:
- A06 – Amoebiasis: infection by Entamoeba histolytica.
- A07 – Other intestinal diseases caused by protozoa: infections caused by Balantidium coli, Giardia intestinalis, Cryptosporidium spec. …
- B50 – Malaria tropica: infection by Plasmodium falciparum.
- B51 – Malaria tertiana: infection by Plasmodium vivax.
- B52 – Malaria quartana: infection by Plasmodium malariae.
- B53 – Other parasitologically confirmed malaria: infection by Plasmodium ovale or simian plasmodia.
- B54 – Malaria, unspecified: Clinically diagnosed malaria without parasitological confirmation.
- B55 – Leishmaniasis: infections caused by Leishmania spec.
- B56 – African trypanosomiasis: infections caused by Trypanosomiasis gambiensis, Trypanosomiasis rhodesiensis …
- B57 – Chagas disease: infection by Trypanosoma cruzi.
- B58 – Toxoplasmosis: infection caused by Toxoplasma gondii.
- B59 – Pneumocystosis: infections caused by Pneumocystis carinii, Pneumocystis jirovecii …
- B60 – Other protozoal diseases, not elsewhere classified: Infections caused by Babesi spec, Acantamoeba spec, Naegleria fowleri …
- B64 – Unspecified protozoal disease.
Symptoms, complaints and signs
Symptoms can vary considerably depending on the parasite that triggers the infection. Generally, a protozoan infection is manifested by fever, flu-like symptoms and general malaise. Sometimes the infected person is more irritable and shows an increased heart rate. Clearly recognizable signals for an illness
are the appearance of nausea, weight loss and vomiting.Complaints in the stomach area, triggered by abdominal pain, diarrhea and flatulence, are also often indicative of an infection. Sometimes bleeding from the rectum can occur.
Diagnosis and course of the disease
Microscopic procedures can be used to diagnose a wide range of infections caused by protozoa. In amebic dysentery, after an incubation period of a few days, the patient has very frequent stools, which can amount to several dozen times per day if the cramps are severe. If left untreated, amebiasis can lead to death. Malaria tropica is manifested by a decrease in hemoglobin concentration and often by a fever that develops rhythmically. Neurological complications may include impaired consciousness. There is a risk of death from malaria tropica. Lamblia infection can easily go unnoticed. This is true for the majority of the approximately ten percent of the world’s population who carry Giardia lamblia in their intestines. Nevertheless, occasional discomfort occurs in the stomach area, which can be manifested by pain on pressure, diarrhea and weight loss. In African sleeping sickness, diagnosis is based on microscopic identification of the causative trypanosomes from a tissue sample. In most cases, this is based on a blood test. In addition, there is the possibility of a diagnostic detection via trypanosome-specific antibodies, which, however, is associated with some uncertainty due to the variability of the parasite in this respect. The course of the disease is two-stage. The hemolymphatic phase is characterized by fever, headache, joint pain and itching. The fever phases occur at intervals. In addition, severe swelling of the lymph nodes may occur. The second phase of the disease – the neurological phase – occurs when the parasite begins to invade the central nervous system. Here, the trypanosomes manage to penetrate the blood–brain barrier. As a result, infected individuals experience a disturbed sleep-wake cycle. This typical symptomatology gave sleeping sickness its name. Without treatment, sleeping sickness is fatal.
Complications
Usually, the protozoan infection leads to symptoms that closely resemble influenza. For this reason, early diagnosis or detection of this disease is not possible in many cases. The patients suffer from a high fever and also from a strong exhaustion. There is also a feeling of malaise and a general feeling of illness. The heart rate of the affected person is also increased by the protozoan infection. Patients lose weight in the course of the disease and suffer from vomiting and nausea. Diarrhea or abdominal pain may also occur, significantly reducing the affected person’s quality of life. In many cases, the protozoan infection also leads to very painful cramps, so that the affected person also suffers from restricted mobility. If there is no treatment, this disease usually leads to the death of the affected person. Pain in the head or joints can also occur due to this disease. Treatment of this disease is done with the help of antibiotics and in most cases leads to a positive course of the disease. Special complications usually do not occur if treatment occurs early.
When should you go to the doctor?
In any case, a protozoan infection must be examined and treated by a physician. There is usually no self-healing with this disease and, in the worst cases, significant limitations in life. Early diagnosis and treatment always have a very positive effect on the course of the disease and can prevent further complications. A doctor should be consulted in the case of protozoal infection when flu-like symptoms occur. The affected person is irritable and generally feels unwell. The symptoms occur without any particular reason and are accompanied by weight loss and nausea. Furthermore, the protozoan infection often also leads to vomiting. In some cases, severe abdominal pain associated with bloating and diarrhea may also be indicative of the protozoal infection and must be evaluated by a physician. The disease can be diagnosed by a general practitioner or in a hospital. For treatment, the affected person is dependent on taking medication.In some cases, it may also result in decreased life expectancy.
Treatment and therapy
Drug treatment is generally by means of antibiotics. In amebic dysentery, these are metronidazole as well as tetracyclines; in addition, chloroquine, an enantiomeric quinine derivative, is used for this purpose. Quinine is classically available as a therapeutic option for malaria, especially for malaria tropica. In the case of giardiasis, treatment is not necessary in all cases. As a rule, the body’s own defenses are sufficient to overcome the infection. In acute disease progression or if debilitating symptoms exist, drug treatment becomes necessary. Nitroimidazoles such as metronidazole, tinidazole, secnidazole or ornidazole are used for this purpose. Treatment of African sleeping sickness usually requires hospitalization. The drugs used for this purpose cause considerable side effects, especially in the second stage of the disease. While suramin can be administered medicinally for treatment in the first stage, the subsequent stage requires the use of arsenic-containing compounds.
Prevention
Prevention is advised to avoid protozoal infection. Primarily, this means avoiding epidemiologically relevant areas to this end. In addition, the known precautionary measures should be observed: Cooking food thoroughly, boiling drinking water, using mosquito nets and anti-insect agents. Occasionally, instructions from the authorities can be found in the form of bathing bans at thermal springs. Possibilities for prophylactic medication exist in the case of malaria. It should be noted here that even chemoprophylaxis with drugs such as chloroquine or proguanil can only provide incomplete protection.
Follow-up care
Because protozoa can potentially infect all organs and it is possible that some protozoa remain in the body even after successful treatment of a protozoal infection, regular follow-up examinations are necessary after a protozoal infection. If the mucous membranes were infected, swabs of the mucous membranes should be taken at regular intervals. In addition, regular examinations of the blood must be carried out by the family doctor. Here, not only the protozoa should be examined, but also the organ values should be measured in order to recognize a possible organ infestation as a long-term consequence of the protozoan infection at an early stage. If poor organ values are measured or if an organ was affected by the protozoan infection, tissue samples (biopsies) of the respective organ should also be taken. In addition, imaging procedures (MRI, ultrasound) may be indicated in this case to detect a possible organ infestation. In addition, a high standard of hygiene should be maintained to prevent recurrence of protozoal infection. This consists in particular of regular hand disinfection and avoidance of public toilets. If the use of public toilets cannot be avoided, intensive disinfection of all body regions that have come into contact with objects inside the public toilet should be carried out afterwards. Clothing should be washed with a sanitary rinse after a protozoan infection to ensure that no protozoa remain in the clothing. In addition, contact with animals that can transmit protozoa should be avoided.
What you can do yourself
Treatment for a protozoan infection depends on which organism was found in the patient’s body. Since some protozoa can cause life-threatening diseases, conscientious diagnosis with appropriate microscopic examinations is important. The patient should then strictly adhere to the doctor’s prescriptions, especially with regard to taking antibiotics. By the time a diagnosis is made, patients have usually suffered for a long time, been fatigued, suffered from nausea, diarrhea and/or vomiting, and have often lost a lot of weight. Therefore, they should pay special attention to a healthy lifestyle during the convalescence period. This includes that the affected persons should not smoke and drink little to no alcohol. In order to stabilize body weight again, healthy, high-fiber meals with plenty of fresh fruit and vegetables should be eaten regularly. However, a healthy lifestyle also includes a regulated sleep-wake rhythm with sufficient sleep. Stress should be avoided during this time. It is also recommended to drink plenty of water during this time.It helps to eliminate toxins and other excess substances from the body. Other detoxifying measures such as sauna sessions, steam baths and sweaty sports are also helpful. Naturopathic doctors and alternative practitioners advise on other detoxification options.
