Parasites PDF

Malaria Parasite: Plasmodium spp. Plasmodium falciparum Plasmodium vivax Plasmodium malariae Plasmodium ovale Disease Transmission Incubation 7-30 days P. falciparum – short P. malariae -longest Prophylaxis Can delay symptoms by weeks to months for P. ovale or P. vivax. Liver (dormant stage may not...

Malaria Parasite: Plasmodium spp. Plasmodium falciparum Plasmodium vivax Plasmodium malariae Plasmodium ovale Disease Transmission Incubation 7-30 days P. falciparum – short P. malariae -longest Prophylaxis Can delay symptoms by weeks to months for P. ovale or P. vivax. Liver (dormant stage may not be killed by anti-parasitic drug) Travel is relevant for at least a year after return. Symptoms Fever, Chills, Sweating, Headache, Nausea and vomiting, Body aches, General malaise. In countries where malaria is frequent, residents often recognize the symptoms as malaria and treat themselves without seeking diagnostic confirmation ("presumptive treatment"). Physical findings may include: Elevated temperature, Perspiration, Weakness, Enlarged spleen In P. falciparum malaria, additional findings may include: Mild jaundice, Enlargement of the liver, increased respiratory rate. Cerebral malaria, with abnormal behavior, impairment of consciousness, seizures, coma, or other neurologic abnormalities Severe anemia due to hemolysis (destruction of the red blood cells) Hemoglobinuria (hemoglobin in the urine) due to hemolysis Pulmonary edema (fluid buildup in the lungs) or acute respiratory distress syndrome (ARDS), which may occur even after the parasite counts have decreased in response to treatment Severe Malaria (P. faciparum) Abnormalities in blood coagulation and thrombocytopenia (decrease in blood platelets) Cardiovascular collapse and shock Acute renal failure Hyperparasitemia, where more than 5% of the red blood cells are infected by malaria parasites Metabolic acidosis (excessive acidity in the blood and tissue fluids), often in association with hypoglycemia Hypoglycemia (low blood glucose). Hypoglycemia may also occur in pregnant women with uncomplicated malaria, or after treatment with quinine. Diagnosis Blood smear Antigen Detection (Rapid test) confirm positives by microscopy PCR – most accurate, but expensive and requires specialized laboratory Serology – Detect antibodies by IFA or ELISA – more useful to detect past infection rather than current infection Chemoprophylaxis About 1500 cases of malaria in US 2/3 P. falciparum 1/3 P. vivax Four questions to ask: Where is the traveler going? When is the traveler going (seasonal risk)? What is the style and duration of travel (backpacking versus hotel)? Who is the traveler (pregnant, visiting friends and relatives)? https://wwwnc.cdc.gov/travel/yellowbook/2020/table-of-contents Parasitic Infections Non-specific clinical signs Limited awareness in medical community Lack of a single broad treatment Clinical presentation aggravated by concurrent disease, poor sanitation. Challenge to treat without harming host Types Helminths Roundworms, tapeworms flukes Protozoa Ectoparasites Nematodes (round worms) Ascaris lumbricodes Asia>>Africa>South America – Moist tropical areas – 1 billion infected (4 million Americans) – 25,000 tons of Ascaris eggs annually Ingest eggs that are found in soil – Hatch in small intestine and/or cecum – Larvae accumulate in liver or pass through portal circulation – Larvae may migrate to heart and lungs In the lungs they travel up the bronchi to trachea/ pharynx – swallow and mature into adult worms in small intestine – produce eggs that are passed in feces Ascaris – stool sample (eggs) Ascaris Clinical presentation Lung – pneumonitis (cough, asthma, dyspnea, pain), eosinophilia, fever, skin rash Abdomen – distension, pain, NV, anal itching, anorexia, malabsorption Complications Intestinal obstruction, intussusception, cholangitis, obstructive jaundice, appendicitis, intestinal perforation, peritonitis, respiratory obstruction Enterobius vermicularis (Pin worms) Common parasitic infection in the US 40 million prevalence in US alone Especially children - family Female emerges at night and deposits 20,000 sticky eggs in perianal, perineal areas Constant itching Debilitating sleep disturbance Weight loss, UTI, appendicitis Enterobius Diagnosis Symptoms – intense perianal itching to asymptomatic – Perineal or vaginal pain in adolescent girls Often spreads through household Eggs remain on clothing and bedding x 72 h Transmitted – fecal/oral route Adult worms deposit ~15,000 eggs Taenai saginata – Beef tapeworm Dipylidium caninum- Dog tapeworm Flukes Blood flukes Schistosoma sp. (Schistosomiasis) Liver flukes Fasciola sp. - Caribbean, Hiawaii and More than 50 countries Intestinal flukes Fasciolopsis (SE Asia ) All involve snail host Protozoa (Microsporidia) Cryptosporidiosis 300,000 cases in US each year Fecal oral transmission –Wild, domestic animals and people Ingestion of contaminated water or recreational water contact –Organism resists chlorine Cryptosporidiosis Presentation – Watery diarrhea – Abdominal cramps or pain – Dehydration – Nausea / vomiting – Fever – Weight Loss – Severe disease in immunocompromised E.g. AIDS Cryptosporidium Giardiasis (Flagellates) #2 Parasitic infection in the US Worldwide problem Fecal/oral transmission Likes cold water (streams) and resists chlorine Backpacking/camping risk MSM risk (oral/anal sex) Cyst from survives in water for months Zoonosis (beaver, cattle, dogs, rodents) Acid in stomach promotes maturation Giardia Giardiasis Presentation Prolonged diarrhea – 2 to 6 weeks Gas / flatulence Greasy stools that tend to float Abdominal cramps Nausea Toxoplasmosis Protozoa found in many animals Infection – undercooked meat or exposure to oocysts Pigs and sheep (tissue cysts) Cats (litter boxes) Special hosts Pregnant women Immunocompromised (e.g. AIDS) Cats – Toxoplasma amplification 1 infection per lifetime in a cat Excrete about 50 million oocysts during infection >90 million cats in the US Oocysts survive in environment for months Litter – dispose of daily – landfill not toilet –Takes about 72 h to mature Pregnancy Routine screening not recommended Mono-like syndrome – serology testing Rare serious neurological complications and congenital infection Transmission increases with gestational age Make partner handle kitty liter! Trichomonas vaginalis STD >7 million cases in US each year Presentation – Male – mild urethritis or asymptomatic – Female – vaginal itching, dysuria, frothy yellowgreen discharge Trichomonas vaginalis