Cryptosporidium Foodborne Disease PDF

PUBH 4104 Foodborne Disease Protozoan Infections Cryptosporidium 1 Cryptosporidium o March/April 1993, Milwaukee, Wisconsin o 403,000 people contracted cryptosporidiosis o Two water treatment plants serviced 800,000 residents and 10 other municipalities o Sout...

PUBH 4104 Foodborne Disease Protozoan Infections Cryptosporidium 1 Cryptosporidium o March/April 1993, Milwaukee, Wisconsin o 403,000 people contracted cryptosporidiosis o Two water treatment plants serviced 800,000 residents and 10 other municipalities o South plant showed turbidity increases starting March 21st but much higher levels from March 23rd -April 5th o Boil water order on April 7th o Plant temporarily closed on April 9th 2 Cryptosporidium o Medical record audit for a 4 month period during and after the outbreak showed: o 88% of those infected did not seek medical care o 11% sought out patient medical care o 1% were hospitalized (average stay was 8 days) o Cost of outbreak was approximately 96.2 million (67% attributed to lost productivity) o A 2 year follow-up study showed 54 death records indicating cryptosporidiosis as a contributing or underlying cause of death, 85% of these cases were associated with AIDS. 3 Cryptosporidium o Cryptosporidium was first isolated in 1907 but it would be 1976 before the first human cases were reported. o Cryptosporidium parvum type 1 is now referred to a Cryptosporidium hominis and is associated with human reservoirs o Cryptosporidium parvum type 2 is now referred to a Cryptosporidium parvum and is associated with bovine and human reservoirs 4 Cryptosporidium o Cryptosporidium felis, C. meleagridis, and a new cervine (deer) genotype are uncommon causes of human infection but are seen more commonly in HIV infected patients. o The protozoan is found in: o Fish, amphibians and reptiles such as snakes, lizards and tortoises o Wild and domesticated birds such as chickens, turkeys, ducks canaries and cockatiels o Mammals such as rodents, cats, dogs, sheep, goats, pigs, deer, cows and humans 5 Transmission o Transmission is via: o Fecal-oral route: o Through oocyst-contaminated drinking or recreational waters o Food o Close contact with humans or other species infected with the organism (petting zoos) o Environmental contamination is common and is worldwide o One study showed oocysts in 27% of drinking water samples from 66 inspected treatment plants 6 Transmission o Implicated food sources include: o Raw vegetables o Basil, cilantro o Fresh-pressed, even ozonated apple cider o Chicken salad o Shellfish o A 1996 CDC report identified a caterer who changed an infants diaper and later prepared chicken salad for a social event, resulting in 50 people being infected. 7 Infection Process o The incubation period (IP) varies from 2 to 14 days, with an average being 7 days. o Children and the elderly see a shorter IP of about 5 days o Cryptosporidiosis affects persons of all ages, but the most severe disease occurs in immunocompromised persons. o Immunocompromised individuals are: o More susceptible to infection o Harder to treat o Likely to see more severe sequelae 8 Infection Process o The round, thick walled oocyst is 4-6 ㎛ in diameter o After ingestion, enzymes and bile salts in the small intestine trigger excystation and 4 small sporozoites are released and enter intestine cells. o Each sporozoite matures and divides asexually to produce 4-8 merozoites that either reinvade the intestinal cells or begin sexual maturation to a zygote and ultimately a sporulated oocyst. 9 Infection Process o About 1 in 5 oocysts are thin walled and help to re-infect the host. o The remaining thick-walled oocysts are passed through the feces to the environment o The mechanism of disease is unknown o As few as 30 oocysts have been known to cause infection the average infectious dose is approximately 130 oocysts o Oocysts are infective immediately after being excreted. 10 Cryptosporidium attached to intestinal lumen 11 Symptoms o Duration of illness is about 2-14 days for immunocompetent people, a chronic state is common in the immunocompromised.but the range is 1-53 days o Major symptom is diarrhea: o On average about 12 stools per day (≤ 25 L/day) o Oocyst excretion may last for several months after diarrhea has stopped. o Nausea, fever, vomiting and cramping may also be seen. 12 Symptoms o May also see: o loss of appetite o Abdominal cramps o Nausea o C. hominis infections also see: o Joint pain, eye pain, recurrent headaches, dizzy spells and fatigue. 13 Pathology o Organism is limited to the intestine and appendix in the immunocompetent host o Organism may be found through the GI tract, in the hepato-biliary system and in the respiratory tract of immunocompromised patients o Illness is usually self-limited in normal, healthy individuals with the symptoms managed with oral rehydration and anti- diarrheals. 14 Pathology o Immunocompromised hosts with: o CD+4 cell counts of >200/mm3 usually experience and acute illness which resolves o CD+4 cell counts of