Malaria Diagnosis and Treatment

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Questions and Answers

What is the shape of gametocytes of P. falciparum?

Crescent-shaped (correct)

Ring-shaped

Spherical

Oval-shaped

What is the function of primaquine in malaria treatment?

Kills merozoites

Prevents relapses

Treats erythrocytic schizont

Kills hypnozoites in the liver (correct)

What is the drug of choice for acute malaria?

Primaquine

Chloroquine (correct)

Doxycycline

Mefloquine

What is the purpose of chemoprophylaxis for travelers to areas with chloroquine-resistant P. falciparum?

To prevent malaria infection Signup and view all the answers

What is the shape of Toxoplasma gondii?

Crescent or banana shape Signup and view all the answers

What is the purpose of insecticide spraying in malaria control?

To kill mosquitoes that transmit malaria Signup and view all the answers

What is the characteristic of trophozoites in infected red blood cells?

Ring-shaped Signup and view all the answers

Where do both sexual and asexual reproductive cycles of Toxoplasma gondii occur?

In the gastrointestinal tract of felines Signup and view all the answers

What is the mode of transmission from mothers to their fetus during pregnancy?

Through congenital transmission (tachyzoite) Signup and view all the answers

What is the definitive host of Toxoplasma gondii?

Domestic cat and other felines Signup and view all the answers

What is the form of the parasite that is infectious?

All parasite stages Signup and view all the answers

What is the location of the nucleus in Toxoplasma gondii?

Sub-terminal Signup and view all the answers

What is the mode of transmission through contaminated food and water?

Through ingestion of oocysts Signup and view all the answers

What occurs in the intestinal tract of felines?

Both sexual and asexual reproduction Signup and view all the answers

What is the result of the fusion of male and female gametes in Toxoplasma?

Formation of an oval, thick-walled oocyst Signup and view all the answers

What is the location where sporozoites are released from the disrupted oocyst?

Small intestine Signup and view all the answers

What is the term for the asexual proliferative forms responsible for cell invasion and clinical disease?

Tachyzoites Signup and view all the answers

What is the characteristic of the oocyst wall?

Thick and resistant to environmental challenges Signup and view all the answers

What is the route of transmission of Toxoplasma from felines to other animals and humans?

Fecal-oral route Signup and view all the answers

What is the primary method of diagnosis for acute and congenital toxoplasmosis infections?

Immunofluorescence assay for IgM antibody Signup and view all the answers

What is the characteristic of bradyzoites?

Slowly dividing Signup and view all the answers

What is the main consequence of congenital toxoplasmosis in infected newborns?

Development of chorioretinitis or mental retardation months or years later Signup and view all the answers

What is the term for the disease caused by Toxoplasma gondii?

Toxoplasmosis Signup and view all the answers

What is the recommended temperature to destroy Toxoplasma cysts in meat?

56°C for 15 minutes Signup and view all the answers

What is the characteristic of primary infections in immunocompetent patients?

Mild and nonspecific illness Signup and view all the answers

What is the recommended treatment for congenital toxoplasmosis in symptomatic or asymptomatic patients?

A combination of sulfadiazine and pyrimethamine Signup and view all the answers

What is the primary means of preventing toxoplasmosis?

Avoiding undercooked meat and contact with cats Signup and view all the answers

What is the typical outcome of acute toxoplasmosis in an immunocompetent individual?

Self-limited disease Signup and view all the answers

What is the primary complication of toxoplasmosis in immunocompromised patients?

Encephalitis Signup and view all the answers

What is the typical manifestation of congenital toxoplasmosis in newborns?

Asymptomatic, but chorioretinitis or mental retardation will develop later Signup and view all the answers

What is the primary host for the sexual cycle of Plasmodium?

Female Anopheles mosquito Signup and view all the answers

What is the term for the sexual cycle of Plasmodium?

Sporogony Signup and view all the answers

What is the location where sporozoites enter the human body?

Bloodstream Signup and view all the answers

What is the stage of Plasmodium that grows and divides into merozoites in the liver?

Trophozoite Signup and view all the answers

What is the term for the asexual cycle of Plasmodium?

Schizogony Signup and view all the answers

What is the result of the periodic release of merozoites in malaria patients?

Recurrent symptoms of chills, fever, and sweats Signup and view all the answers

What is the number of species of Anopheles mosquitoes that can transmit Plasmodium?

Over 60 Signup and view all the answers

What is the geographical distribution of malaria?

Endemic in over 100 countries in the tropics and subtropics Signup and view all the answers

What is the primary mode of transmission of Toxoplasma from infected felines to humans?

Through ingestion of contaminated food and water with sporulated oocysts Signup and view all the answers

What is the mode of transmission of Toxoplasma from mothers to their fetus during pregnancy?

Through congenital transmission Signup and view all the answers

What is the common mode of transmission of Toxoplasma through ingestion of undercooked meat?

Through ingestion of bradyzoites in infective meat Signup and view all the answers

What is the route of transmission of Toxoplasma from felines to other animals and humans?

Through ingestion of contaminated food and water with sporulated oocysts Signup and view all the answers

What is the mode of transmission of Toxoplasma through contaminated food and water?

Through ingestion of sporulated oocysts in contaminated food and water Signup and view all the answers

What is the primary mode of transmission of Toxoplasma in humans?

Through ingestion of contaminated food and water with sporulated oocysts Signup and view all the answers

What is the mode of transmission of Toxoplasma through congenital transmission?

From mothers to their fetus during pregnancy Signup and view all the answers

What is the common mode of transmission of Toxoplasma through ingestion of infective meat?

Through ingestion of bradyzoites in infective meat Signup and view all the answers

What is the primary means of transmission of Plasmodium to humans?

Through the bite of an infected female Anopheles mosquito Signup and view all the answers

Where do sporozoites enter the human body?

Through the circulatory system, from the saliva of the biting mosquito Signup and view all the answers

What is the role of the female Anopheles mosquito in the transmission of Plasmodium?

Vector and intermediate host Signup and view all the answers

How do merozoites infect red blood cells?

After being released from the liver cells Signup and view all the answers

What is the result of the bite of an infected female Anopheles mosquito?

Introduction of sporozoites into the blood Signup and view all the answers

What is the site where Plasmodium penetrates the host cells?

Hepatocytes Signup and view all the answers

What is the stage of the parasite that is responsible for transmission to humans?

Sporozoite Signup and view all the answers

What is the primary route of transmission of Plasmodium?

Vector-borne transmission through the bite of an infected mosquito Signup and view all the answers

What is the mode of transmission of Plasmodium to humans?

Through the bite of an infected female Anopheles mosquito Signup and view all the answers

Where do the gametocyte-containing red blood cells get ingested?

In the mosquito's gut Signup and view all the answers

What is the role of the female Anopheles mosquito in the life cycle of Plasmodium?

It acts as a vector for transmission to humans Signup and view all the answers

What is the stage of Plasmodium that is transmitted to humans?

Sporozoite Signup and view all the answers

How do sporozoites enter the human body?

Through the skin when bitten by an infected mosquito Signup and view all the answers

What is the mode of transmission of Plasmodium from mother to fetus?

Through vertical transmission Signup and view all the answers

What is not a mode of transmission of Plasmodium?

Through airborne transmission Signup and view all the answers

What is the primary means of transmission of Plasmodium?

Through the bite of an infected female Anopheles mosquito Signup and view all the answers

What is a common symptom of malaria?

Fever Signup and view all the answers

What is a potential complication of P. falciparum malaria?

Cerebral malaria Signup and view all the answers

What is a typical laboratory diagnosis method for malaria?

Microscopic examination of blood Signup and view all the answers

What is a consequence of intravascular hemolysis in malaria?

All of the above Signup and view all the answers

What is a characteristic of cerebral malaria?

Anoxia, ischemia, and numerous small hemorrhages Signup and view all the answers

What is a common finding in malaria patients?

All of the above Signup and view all the answers

What is a potential consequence of untreated P. falciparum malaria?

Death Signup and view all the answers

What is a characteristic of malaria?

Acute onset of fever and chills Signup and view all the answers

What is the typical duration until symptoms appear after the erythrocytic cycle begins?

10-14 days Signup and view all the answers

What is the likely cause of fever in malaria?

Release of interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNF-α) Signup and view all the answers

What is the periodicity of febrile episodes in P. falciparum, P. vivax, and P. ovale infections?

48 hours Signup and view all the answers

What is the characteristic of the asexual cycle in malaria?

Synchronous and periodic Signup and view all the answers

What is the stage of the parasite that grows and divides into merozoites in the liver?

Sporozoite Signup and view all the answers

What is the typical duration of febrile episodes in malaria?

10-14 days Signup and view all the answers

What is the result of the processing of red blood cell debris by macrophages?

Release of interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNF-α) Signup and view all the answers

What is the timing of the onset of symptoms in malaria?

10-14 days after the erythrocytic cycle begins Signup and view all the answers

What is the term for the disease caused by Toxoplasma gondii?

Toxoplasmosis Signup and view all the answers

What are the characteristics of bradyzoites?

Similar to tachyzoites, but smaller and dividing more slowly Signup and view all the answers

What is the result of primary infections in immunocompetent patients?

Mild, and nonspecific illness Signup and view all the answers

What is the classification of symptomatic toxoplasmosis?

Acute, subacute, chronic, or congenital Signup and view all the answers

What is the term for the asexual proliferative forms responsible for cell invasion and clinical disease?

Tachyzoites Signup and view all the answers

What is the characteristic of the oocyst?

Oval and thick-walled Signup and view all the answers

What is the route of transmission of Toxoplasma from felines to other animals and humans?

Fecal-oral route Signup and view all the answers

What is the characteristic of tachyzoites?

Rapidly multiplying forms Signup and view all the answers

What is the primary method of diagnosis for acute and congenital toxoplasmosis infections?

Immunofluorescence assay for IgM antibody Signup and view all the answers

What is the purpose of the immunofluorescence assay for IgM antibody?

To diagnose acute and congenital toxoplasmosis infections Signup and view all the answers

What is the importance of laboratory diagnosis in toxoplasmosis?

To diagnose and confirm acute and congenital toxoplasmosis infections Signup and view all the answers

What is the laboratory method used to diagnose acute toxoplasmosis?

Immunofluorescence assay for IgM antibody Signup and view all the answers

What is the laboratory diagnosis method used to confirm congenital toxoplasmosis?

Immunofluorescence assay for IgM antibody Signup and view all the answers

What is the significance of IgM antibody in the diagnosis of toxoplasmosis?

It indicates acute infection Signup and view all the answers

Why is serologic diagnosis important in toxoplasmosis?

To diagnose and confirm acute and congenital toxoplasmosis infections Signup and view all the answers

What is the role of laboratory diagnosis in the management of toxoplasmosis?

To diagnose and confirm acute and congenital toxoplasmosis infections and guide treatment Signup and view all the answers

What is the primary method used in the laboratory diagnosis of malaria?

Microscopic examination of blood Signup and view all the answers

What type of smears are used in the diagnosis of malaria?

Thin and thick Giemsa-stained smears Signup and view all the answers

What is the purpose of the thick smear in the diagnosis of malaria?

To screen for the presence of the parasite Signup and view all the answers

What is the purpose of the thin smear in the diagnosis of malaria?

To identify the species of the parasite Signup and view all the answers

Which of the following is NOT a laboratory diagnostic method for malaria?

Blood chemistry analysis Signup and view all the answers

What is the primary advantage of microscopic examination of blood in the diagnosis of malaria?

It can detect the presence of the parasite in the blood Signup and view all the answers

What is the significance of Giemsa stain in the diagnosis of malaria?

It helps to visualize the parasite in the blood Signup and view all the answers

What is the role of the laboratory in the diagnosis of malaria?

To confirm the clinical diagnosis Signup and view all the answers

What is the result of the fusion of male and female gametes in Toxoplasma?

Formation of an oval, thick-walled oocyst Signup and view all the answers

Where are sporozoites released from the disrupted oocyst?

In the small intestine Signup and view all the answers

What is the term for the asexual proliferative forms responsible for cell invasion and clinical disease?

Tachyzoites Signup and view all the answers

What is the characteristic of the oocyst wall?

Thick and resistant to environmental challenges Signup and view all the answers

What is the route of transmission of Toxoplasma from felines to other animals and humans?

Fecal-oral route Signup and view all the answers

What is the characteristic of bradyzoites?

They are smaller than tachyzoites and divide more slowly Signup and view all the answers

What is the term for the disease caused by Toxoplasma gondii?

Toxoplasmosis Signup and view all the answers

What is the characteristic of primary infections in immunocompetent patients?

They are usually asymptomatic or produce a mild, nonspecific illness Signup and view all the answers

What is the primary route of transmission of Toxoplasma from felines to other animals and humans?

Through fecal-oral route Signup and view all the answers

What is the typical outcome of acute toxoplasmosis in an immunocompetent individual?

Mild, non-specific illness Signup and view all the answers

What is the form of the parasite that is infectious?

Oocyst Signup and view all the answers

What is the term for the asexual proliferative forms responsible for cell invasion and clinical disease?

Tachyzoite Signup and view all the answers

What is the characteristic of the oocyst wall?

Thick and resistant Signup and view all the answers

What is the disease caused by Toxoplasma gondii?

Toxoplasmosis Signup and view all the answers

What is the primary method of prevention of toxoplasmosis?

Proper hygiene and food handling Signup and view all the answers

What is the characteristic of bradyzoites?

Slowly multiplying Signup and view all the answers

What is the primary treatment for congenital toxoplasmosis in symptomatic or asymptomatic patients?

A combination of sulfadiazine and pyrimethamine Signup and view all the answers

What is the typical outcome of acute toxoplasmosis in an immunocompetent individual?

A self-limited disease that usually resolves on its own Signup and view all the answers

What is the primary complication of toxoplasmosis in immunocompromised patients?

Disseminated disease, primarily encephalitis Signup and view all the answers

What is the recommended treatment for acute toxoplasmosis in immunocompetent individuals?

No treatment is required, as the disease is self-limited Signup and view all the answers

What is the primary treatment for disseminated disease in immunocompromised patients?

A combination of sulfadiazine and pyrimethamine Signup and view all the answers

What is the recommended treatment for congenital toxoplasmosis in newborns?

A combination of sulfadiazine and pyrimethamine Signup and view all the answers

What is the primary goal of treatment for toxoplasmosis in immunocompromised patients?

To reduce the severity of symptoms Signup and view all the answers

What is the primary treatment for toxoplasmosis in pregnant women?

A combination of sulfadiazine and pyrimethamine Signup and view all the answers

What is the primary function of chloroquine in the treatment of malaria?

To kill the merozoites and reduce parasitemia Signup and view all the answers

Which of the following is used to prevent relapses of P. vivax and P. ovale?

Primaquine Signup and view all the answers

What is the purpose of chemoprophylaxis for travelers to areas with chloroquine-resistant P. falciparum?

To prevent infection with P. falciparum Signup and view all the answers

What is the duration of chloroquine chemoprophylaxis for travelers to areas where the other three plasmodia are found?

2 weeks before and 6 weeks after departure Signup and view all the answers

What is the complete treatment of malaria?

Destruction of the erythrocytic schizont, the hepatic schizont, and the erythrocytic gametocyte Signup and view all the answers

What is the purpose of PCR-based tests for Plasmodium nucleic acids?

To confirm the diagnosis of malaria when blood smears are negative Signup and view all the answers

Study Notes

Plasmodium

Ring-shaped trophozoites can be seen within infected red blood cells.
Gametocytes of P.falciparum are crescent-shaped ("banana-shaped"), whereas those of the other plasmodia are spherical.
PCR-based test for Plasmodium nucleic acids can be useful if blood smears do not reveal the diagnosis.
The complete treatment of malaria requires the destruction of three parasitic forms: the erythrocytic schizont, the hepatic schizont, and the erythrocytic gametocyte.
Chloroquine is the drug of choice for acute malaria, killing merozoites and reducing parasitemia, but not affecting the hypnozoites of P.vivax and P.ovale in the liver.
Primaquine is used to prevent relapses, killing the hypnozoites of P.vivax and P.ovale in the liver.
Control and prevention of malaria involve insecticide spraying, improvements in land drainage, and removal of standing water, particularly in inhabited areas.
Chemoprophylaxis of malaria for travelers to areas where chloroquine-resistant P.falciparum is endemic consists of mefloquine or doxycycline.
Travelers to areas where the other three plasmodia are found should take chloroquine starting 2 weeks before arrival and continuing for 6 weeks after departure.
Several vaccines are under development.

Toxoplasma

Toxoplasma gondii is an obligate intracellular sporozoan that causes toxoplasmosis.
The parasite has a crescent or banana shape, with a sub-terminal nucleus.
The major morphologic forms of the parasite are the tachyzoite, tissue cyst, and oocyst.
All parasite stages are infectious.
The definitive host is the domestic cat and other felines, while humans and other mammals are intermediate hosts.
Human infections are found in every region of the globe, with a higher incidence in the tropics and lower in cold regions.
Transmission of Toxoplasma occurs through congenital transmission from mothers to their fetus during pregnancy, ingestion of contaminated food and water with sporulated oocysts from cat feces, and ingestion of bradyzoites (tissue cysts) in infective meat.
The life cycle in the definitive host (felines) involves sexual reproduction of T.gondii in the intestinal tract, leading to the formation of an oval, thick-walled oocyst that is shed in the feces.
The life cycle in intermediate hosts (humans and other mammals) involves the ingestion of sporozoites, which then invade the gut wall, differentiate into rapidly multiplying tachyzoites, and eventually develop into cysts containing bradyzoites.
Tachyzoites are the asexual proliferative forms responsible for cell invasion and clinical disease, but are not infective on ingestion.
Tissue cysts contain bradyzoites, which are similar to tachyzoites but divide more slowly, and are infectious to the animal that ingests them.
The oocyst is ovoid, with a thick wall that makes it resistant to most environmental challenges, and is responsible for the spread of the parasites from felines to other animals and humans via the fecal-oral route.
Clinical disease manifestations include asymptomatic or mild, nonspecific illness, as well as acute, subacute, chronic, or congenital toxoplasmosis, which can result in abortion, stillbirth, or neonatal disease with encephalitis, chorioretinitis, and hepatosplenomegaly.
Laboratory diagnosis is primarily through serologic procedures, including an immunofluorescence assay for IgM antibody.
Treatment involves a combination of sulfadiazine and pyrimethamine for acute toxoplasmosis in immunocompetent individuals, congenital toxoplasmosis, and disseminated disease in immunocompromised patients.
Prevention involves cooking meat thoroughly to kill the cysts, especially for pregnant women, and avoiding contact with cats.

Toxoplasma

Toxoplasma gondii is an obligate intracellular sporozoan that causes toxoplasmosis.
It differs from Plasmodium in that both sexual and asexual reproductive cycles occur within the gastrointestinal tract of felines (the definitive host).
The parasite has a crescent or banana shape, with a sub-terminal nucleus.
Major morphologic forms include the tachyzoite, tissue cyst, and oocyst, all of which are infectious.
The definitive host is the domestic cat and other felines, while humans and other mammals are intermediate hosts.

Epidemiology of Toxoplasma

Human infections are found in every region of the globe, with higher incidence in the tropics and lower incidence in cold regions.
Transmission occurs through three ways:
- Congenital: from mothers to their fetus during pregnancy (tachyzoite).
- Ingestion of contaminated food and water with sporulated oocysts from cat feces.
- Ingestion of bradyzoites (tissue cysts) in infective meat (raw or undercooked).

Life Cycle of Toxoplasma

Sexual reproduction of T. gondii occurs only in the intestinal tract of felines, most commonly in the domestic cat.
Ingested parasites enter epithelial cells of the ileum and undergo schizogony, releasing merozoites that infect adjacent epithelial cells.

Plasmodium

The vector and definitive host for plasmodia is the female Anopheles mosquito (only the female takes a blood meal).
There are two phases in the life cycle: the sexual cycle, which occurs primarily in mosquitoes, and the asexual cycle, which occurs in humans, the intermediate hosts.

Distribution and Transmission of Plasmodium

Malaria is endemic in over 100 countries in the tropics and subtropics, and was formerly present in many temperate regions.
Transmission occurs when sporozoites are injected along with mosquito saliva during blood feeding by females of over 60 species of Anopheles mosquitoes.

Life Cycle of Plasmodium

The life cycle begins with the introduction of sporozoites into the blood from the saliva of the biting mosquito.
The sporozoites enter the circulatory system and are carried to the liver, where they penetrate hepatocytes and undergo exo-erythrocytic development.
The erythrocytic cycle involves the release of merozoites from the liver cells, which infect red blood cells.
The merozoites differentiate into ring-shaped trophozoites, which grow into ameboid forms and eventually produce schizonts filled with merozoites.

Pathogenesis of Plasmodium

Ten to fourteen days after the erythrocytic cycle begins, the parasite numbers reach a density that induces the onset of symptoms, including fever, chills, diarrhea, headache, and sometimes pulmonary and cardiac symptoms.
Fever coincides with red blood cell lysis and is likely caused by the release of interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNF-α) by macrophages activated during the processing of red blood cell debris.
The periodicity of fever episodes is 48 hours for P. falciparum, P. vivax, and P. ovale infections (tertian malaria) and 72 hours for P. malariae infection (quartan malaria).

Malaria

Destruction of erythrocytes leads to anemia and enlargement of the liver and spleen.
Massive hemoglobinuria (blackwater fever) is a consequence of intravascular hemolysis, which can lead to acute tubular necrosis and renal failure.
Cerebral malaria occurs in P. falciparum malaria, where late-stage schizonts elaborate proteins that are expressed on the erythrocyte surface, promoting aggregation and adhesion to capillary endothelial cells, constricting capillary blood flow and causing anoxia, ischemia, and numerous small hemorrhages.

Clinical Disease

Malaria is caused by four plasmodia species: P. vivax, P. ovale, P. malariae, and P. falciparum.
Malaria presents with abrupt onset of fever and chills, accompanied by headache, myalgia, and arthralgia, about 2 weeks after the mosquito bite.
The fever spike can reach 41°C, frequently accompanied by shaking chills, nausea, vomiting, and abdominal pain.
Splenomegaly and hepatomegaly are seen in most patients, and anemia is prominent.

Laboratory Diagnosis

Diagnosis rests on microscopic examination of blood, using both thick and thin Giemsa-stained smears.
The thick smear is used to screen for the presence of organisms, and the thin smear is used for species identification.

Toxoplasma

Life Cycle in Intermediate Hosts

After ingestion by a susceptible animal or human, sporozoites are released from the disrupted oocyst.
In the small intestine, the cysts rupture and release forms that invade the gut wall, where they are ingested by macrophages and differentiate into rapidly multiplying (tachyzoites).
Tachyzoites enter host cells in the brain, muscle, and other tissues, where they develop into cysts in which the parasites multiply slowly.

Clinical Disease and Clinical Findings

Toxoplasma gondii causes toxoplasmosis, which may be classified as acute, subacute, chronic, or congenital.
Most primary infections in immunocompetent patients are asymptomatic or produce a mild, nonspecific illness.

Plasmodium Life Cycle

The sexual cycle begins in the human red blood cells when some merozoites develop into male and others into female gametocytes.
The gametocyte-containing red blood cells are ingested by the female Anopheles mosquito, producing a female macrogamete and eight sperm-like male microgametes.

Pathogenesis

Ten to fourteen days after the erythrocytic cycle begins, the parasite numbers reach a density that induces the onset of symptoms.
Fever, chills, diarrhea, headache, and sometimes pulmonary and cardiac symptoms are typical.
Fever coincides with red blood cell lysis, and is likely to be caused by the release of interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNF-α) by macrophages activated during the processing of red blood cell debris.

Toxoplasma

Toxoplasma gondii causes toxoplasmosis, which can present with various symptoms and severity
Acute toxoplasmosis symptoms include painful, swollen lymph glands, fever, headache, anemia, muscle pain, and pulmonary complications
Congenital toxoplasmosis can result in abortion, stillbirth, or neonatal disease with encephalitis, chorioretinitis, and hepatosplenomegaly
Fever, jaundice, and intracranial calcifications are also seen in congenital toxoplasmosis
Most infected newborns are asymptomatic, but chorioretinitis or mental retardation may develop months or years later
In immunocompromised hosts, toxoplasmosis is a serious, often fatal disease, causing life-threatening disseminated disease, primarily encephalitis

Laboratory Diagnosis

Serologic procedures, specifically immunofluorescence assay for IgM antibody, are used to diagnose acute and congenital infections

Treatment

Acute toxoplasmosis in immunocompetent individuals is usually self-limited
Congenital toxoplasmosis, whether symptomatic or asymptomatic, and disseminated disease in immunocompromised patients should be treated with a combination of sulfadiazine and pyrimethamine

Prevention

Cooking meat thoroughly to kill cysts is the most effective means of preventing toxoplasmosis
Pregnant women should avoid undercooked meat and contact with cats
Cysts in meat can be destroyed by proper cooking (56°C for 15 minutes) or freezing to –20°C
Drinking water from lakes and rivers should be boiled

Plasmodium (Malaria)

Clinical Disease

Malaria is caused by four Plasmodium species: Plasmodium vivax, Plasmodium ovale, Plasmodium malariae, and Plasmodium falciparum
Malaria presents with abrupt onset of fever and chills, accompanied by headache, myalgia, and arthralgia
Splenomegaly and hepatomegaly are seen in most patients, and anemia is prominent
Untreated malaria caused by P. falciparum is potentially life-threatening due to extensive brain (cerebral malaria) and kidney (black water fever) damage
Relapses of P. vivax and P. ovale malaria can occur up to several years after the initial illness due to hypnozoites latent in the liver

Laboratory Diagnosis

Diagnosis is based on microscopic examination of blood using both thick and thin Giemsa-stained smears
The thick smear is used to screen for the presence of organisms, and the thin smear is used for species identification

Toxoplasma Life Cycle in Intermediate Hosts

After ingestion by a susceptible animal or human, sporozoites are released from the disrupted oocyst
In the small intestine, the cysts rupture and release forms that invade the gut wall, where they are ingested by macrophages and differentiate into rapidly multiplying (tachyzoites)
Tachyzoites enter host cells in the brain, muscle, and other tissues, where they develop into cysts in which the parasites multiply slowly (bradyzoites)

Malaria

Ring-shaped trophozoites are seen within infected red blood cells.
Gametocytes of P. falciparum are crescent-shaped, while those of other plasmodia are spherical.
PCR-based test for Plasmodium nucleic acids can be useful if blood smears do not reveal diagnosis.
Complete treatment requires destruction of three parasitic forms: erythrocytic schizont, hepatic schizont, and erythrocytic gametocyte.
Chloroquine is the drug of choice for acute malaria, but does not affect hypnozoites of P. vivax and P. ovale in the liver.
Primaquine is used to prevent relapses.

Malaria Control and Prevention

Control measures include insecticide spraying, improvements in land drainage, and removal of standing water.
Chemoprophylaxis for travelers to areas with chloroquine-resistant P. falciparum involves mefloquine or doxycycline.
Travelers to areas with other plasmodia should take chloroquine starting 2 weeks before arrival and continuing for 6 weeks after departure.

Toxoplasma

Clinical Disease and Findings

Acute toxoplasmosis symptoms include painful, swollen lymph glands, fever, headache, anemia, muscle pain, and sometimes pulmonary complications.
Congenital toxoplasmosis can result in abortion, stillbirth, or neonatal disease with encephalitis, chorioretinitis, and hepatosplenomegaly.
In immunocompromised hosts, toxoplasmosis can be a serious, often fatal disease.

Laboratory Diagnosis

Serologic procedures are the primary method of diagnosis.
Immunofluorescence assay for IgM antibody is used for acute and congenital infections.

Treatment

Acute toxoplasmosis in immunocompetent individuals is usually self-limited.
Congenital toxoplasmosis, whether symptomatic or asymptomatic, and disseminated disease in immunocompromised patients should be treated with a combination of sulfadiazine and pyrimethamine.

Prevention

Cooking meat thoroughly can kill cysts and prevent toxoplasmosis.
Pregnant women should avoid undercooked meat and contact with cats.
Drinking water from lakes and rivers should be boiled.

Life Cycle in Intermediate Hosts

After ingestion, sporozoites are released from the disrupted oocyst.
Sporozoites invade the gut wall, where they are ingested by macrophages and differentiate into tachyzoites.
Tachyzoites enter host cells in the brain, muscle, and other tissues, where they develop into cysts containing bradyzoites.

Life Cycle Forms

Tachyzoites are asexual proliferative forms responsible for cell invasion and clinical disease.
Bradyzoites are similar to tachyzoites but are smaller and divide more slowly.
Oocysts are ovoid, with a thick wall that makes them resistant to environmental challenges.

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This quiz covers the diagnosis and treatment of malaria, including the identification of Plasmodium parasites and the destruction of different parasitic forms.