Cryptosporidium and Giardia shedding among humans and animals in coastal Orissa, India Miles E. Daniels Woutrina A. Smith, Arpit Shrivastava, Priyadarshi Sahu, Mitsunori Odagiri, Pravas R. Misra, Pinaki Panigrahi, Mrutyunjay Suar, Marion W. Jenkins
Sanitation and exposure to pathogens in rural Puri Open defecation widespread lack improved sanitation Frequent contact with livestock ~ 80% HH own at least one species of livestock Humans and livestock share community water sources
Cryptosporidium and Giardia Protozoal parasites not bacteria or viruses Zoonotic potential Infectious for days to months in environment 200 million symptomatic cases per year in Asia, Africa, and Latin America Cryptosporidium recently noted as 2 nd largest cause of diarrhea in < 2yr old in India
Project goals Estimate Cryptosporidium and Giardia prevalence in co-existing humans and animals Examine associations between host characteristics and infection Estimate environmental loading of Cryptosporidium and Giardia from animals
Methods
General study design Screen human feces (n = 85) from three diarrhea wards Screen animal feces (n =587 individual = 111 pooled) throughout study region & Outcome measurements from screening were: 1: parasite presence/absence 2: parasite counts per gram of wet feces
Additional host information Age Gender Residence Residence Species < 5 yr 5 59 yr > 59 yr Urban or Rural Urban or Rural 7 species cattle, buffalo, sheep, goat, cat, chicken, and dog
Statistical models Human Animal Outcome variable presence / absence parasites counts of parasites Predictor variables Statistical model residence age gender logistic regression residence species negative binomial regression
Model averaging and AIC: Mode of inference Don t just use best model for inference, but all candidate models Use AIC weights to weight information from candidate models to calculate averaged model coefficients Use Evidence Ratio (ER) to infer relative importance of averaged coefficients
Results
Cryptosporidium % Posi ve Giardia % Posi ve Human screening results 20% *12% overall prevalence of both parasites in humans 15% 10% 5% 0% 20% Overall Female Male Rural Urban < 5 yrs 5-59 yrs > 59 yrs *statistical models found no evidence of associations 15% 10% 5% 0% Overall Female Male Rural Urban < 5 yrs 5-59 yrs > 59 yrs
Cryptosporidium % Posi ve Giardia % Posi ve Animal screening results 100% 75% 50% *35% overall prevalence of Giardia 25% 0% 100% 75% Overall Ca le Buffalo Goat Sheep Dog Chicken Cat Rural Urban 50% *17% overall prevalence of Cryptosporidium 25% 0% Overall Ca le Buffalo Goat Sheep Dog Chicken Cat Rural Urban
Statistical results for animal shedding Giardia Effect Constant Rural Buffalo Goat Sheep Dog Chicken Coefficient β 0 β 1 β 2 β 3 β 4 β 5 β 6 M ave 4.697 1.873-6.008-5.643-0.365 3.604-39.734 ER 4.060 >1000 >1000 >1000 >1000 >1000 RR 6.510 0.002 0.004 0.694 36.745 <0.001 Substantial evidence that shedding rates differ by rural and urban settings: Rural animals at greater risk Decisive evidence that shedding rates differ between species: Dogs at highest risk and buffalo at lowest risk (relative to cattle)
Statistical results for animal shedding Cryptosporidium Effect Constant Rural Buffalo Goat Sheep Dog Chicken Coefficient β 0 β 1 β 2 β 3 β 4 β 5 β 6 M ave -2.27 1.412-1.303 4.398 7.694 5.582-19.457 ER 1.993 >1000 >1000 >1000 >1000 >1000 RR 4.104 0.273 81.288 2195.138 265.602 <0.001 Decisive evidence that shedding rates differ between species: Sheep at highest risk and buffalo at lowest risk (relative to cattle)
Estimating animal loading of parasites X Dog Goat Sheep Buffalo = Cattle parasites counts (parasites g -1 ) X fecal production (g individual -1 day -1 ) animal census (individual) Source: Puri District Government 2007 environmental loading from animals (parasites day -1 )
Animal loading estimates Giardia Cryptosporidium Host Population Total Load % Total Load % Species (N) (cyst day -1 ) (oocyst day -1 ) Cattle 429,897 3.37 E + 12 (>99%) 2.3 E + 09 (9.58%) Buffalo 11,204 2.73 E + 08 (0.01%) 1.4 E + 07 (0.06%) Goat 132,767 9.29 E + 07 (<0.01%) 1.9 E + 09 (7.92%) Sheep 57,466 8.96 E + 09 (0.26%) 1.9 E + 10 (79.17%) Dog 11,837 1.19 E + 10 (0.35%) 8.1 E + 07 (0.34%) Cattle are biggest animal shedders of Giardia in study region Sheep and cattle are two biggest animal shedders of Cryptosporidium in study region
Humans: Conclusions Both parasites are present in study region and likely at higher prevalence than reported from our study Small sample size may have precluded ability to detect differences between age, gender, or residence status Animals: Parasites from cattle in rural areas may present public health concern considering high loading rates, frequent human contact with feces, and previous studies finding zoonotic strains in bordering states
Comments or Questions? meddaniels@ucdavis.edu