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. 2018 Jan 29;12(1):e0006231. doi: 10.1371/journal.pntd.0006231

Table 1. Main parameters used in the quantitative microbial risk assessment and susceptible-infected-recovered models developed to simulate waterborne diarrheal infections in children < 5 in Puri District due to Cryptosporidium and Giardia in drinking water from deep (DTW) and shallow (STW) tubewells over two monsoon seasons.

Parameter Symbol (Fig 1): Description (distribution) Parameter value(s) of distribution or point estimate Source
QMRA parameter set
MR: Method recovery (beta binomial)
Crypto. mean = 55%, Giardia mean = 34%
Crypto. = α = 1.9, β = 1.9
Giardia = α = 3.0, β = 6.0
[15]
V: Viability (beta binomial)
Crypto. mean = 38%, Giardia mean = 13%
Crypto. α = 1.65, β = 2.46
Giardia α = 2.93, β = 17.4
[25, 26]
H (HUM scenario): Mean fraction of human parasites Crypto. = 100%, Giardia = 100% [15, 2729]
H (ENV scenario): Mean fraction of human parasites Crypto. = 6%, Giardia = < 1% [15, 2729]
H (MST scenario): Mean fraction of human parasites DTW 2012 = 50%, STW 2012 = 16%
DTW 2013 = 20%, STW 2013 = 33%
[15, 3038]
Z^ (ENV and MST scenario): Mean fraction of non-human parasites infectious-to-humans [zoonotic faction] Crypto. = 41%, Giardia = 19% [15, 3038]
Sp (HUM, ENV, MST scenarios): Mean fraction of parasites of a species infectious-to-humans Sp=H+(1H)×Z^
LR: Reduction from boiling water Crypto. = 6 Log10, Giardia = 6 Log10 [39]
L: Liters of water ingested per day (uniform) a = 0.893, b = 1.39 [40, 41]
r: Exponential dose response parameter
(triangular dist.)*
Crypto. = a = 0.00021, c = 0.0042, b = 0.0500
Giardia = a = 0.0097, c = 0.0198, b = 0.0358
[4244]
SIR parameter set
TW: Probability of using a particular tubewell type DTW = p = 48%
STW = p = 52%
Base line survey
B: Probability of boiling tubewell water before drinking (Bernoulli) DTW = p = 9%
STW = p = 16%
Base line survey
P(s): Morbidity ratio for diarrheic infection (Bernoulli, where p is uniform**) Crypto. = p = a = 29%, b = 68%
Giardia = p = a = 49%, b = 59%
[9, 4547]
D: Duration of illness (gamma)
Crypto. mean = 10 days, Giardia mean = 11days
Crypto. = shape = 1.1, scale = 9.2
Giardia = shape = 3.2, scale = 3.4
[17, 4851]
Re: Reduced recall of diarrhea 2 or more days after occurrence (Bernoulli, where p is uniform**) p = a = 12%, b = 52% [52]

* a, c, b for the triangular distribution are minimum, mode, and maximum respectively.

** a and b for uniform distribution are minimum and maximum.