Please see below for the latest update on Merced, Stanislaus, and Yolo County wastewater data.

  • Weeks 114-115: 12/24 - 01/06
  • Weeks 116-117: 01/07 - 01/20

General Update at County Level

Aggregated trend lines for counties are calculated using the right-aligned 10-day trimmed average for each site. For each date, an individual site trimmed smoothed value for the day is multiplied by the plant’s population, then these are summed and divided by the total population of all selected sites. This calculation results in the trimmed weighted average \(target/PMMoV_{w,t}\) for day t, as in the following equation for the m selected plants: \[\text{trimmed } target/PMMoV_{t} = \frac {\sum_{i=1}^m target/PMMoV_{i,t}}{\sum_{i=1}^m pop_i}\]

Percentage of change

Percent change
Virus Merced County Stanislaus County Yolo County
SARS-CoV-2 +1.7% 7.7% 41%
Norovirus 13% 6.1% 51%
RSV 10.6% 23.2% 54.3%
Influenza A NA NA +39.1%
Influenza B 34.5% 97.1% 15.2%
HMPV +118% +142% 55.6%
Parainfluenza +30.3% +8.3% 53.7%
Percent change is calculated here using the average of measurements over the past two weeks compared to the average of measurements from the prior two weeks. Results below the limit of detection are included in the averages as half the limit of detection.
Criteria: need at least three positive detections in the last 14 days to report a percent change.
NA: if the above criteria is not met and there were no data available in the last 7 days.
Sporadic: Labeled as sporadic detections if the above criteria is not met, but there is at least 1 positive detection in the last 14 days.
ND: Non-detect (i.e., below the limit of detection) if there were no detections in the last 14 days.
+LL: increasing but at low levels. If the above criteria is met but there were no positive detections or no data in the prior 14 days.
+Sharply: percent change is greater than 500%.
Weeks 114-115: 12/24 - 01/06
Weeks 116-117: 01/07 - 01/20

Current wastewater level

Current wastewater level
Virus Merced Stanislaus Yolo
SARS-CoV-2 High High Medium
Norovirus Medium High Low
RSV Low Medium Medium
Influenza A Low Medium Low
Influenza B Low Low Low
HMPV Low Low Low
Parainfluenza Low Low Low
If there have not been at least one positive sample in the last 7 days and at least three positive samples in the last 14 days, a low categorization is assigned.
For non-seasonal pathogens, the boundaries of the low, medium, and high labels are defined as the tertiles of all data available for that pathogen within a given site or county.
For seasonal pathogens, the boundaries of the low, medium, and high labels are defined as the thirds of the 95th percentile value for all of the data available for that pathogen within a given site or county.

Trend test at County level

Mann-Kendall trend test

Mann-Kendall trend test
Virus Merced County Stanislaus County Yolo County
SARS-CoV-2 Very likely downward Very likely downward Very likely downward
Norovirus No Trend No Trend Very likely downward
Rotavirus Very likely downward Likely downward Very likely downward
Hepatitis A Virus Upward No Trend No Trend
Candida auris No Trend No Trend No Trend
Enterovirus D68 No Trend No Trend Likely downward
RSV Very likely downward Very likely downward Likely downward
Influenza A No Trend No Trend Downward
Influenza B Very likely downward No Trend Likely downward
HMPV Likely upward Likely downward Very likely downward
Parainfluenza Very likely downward Very likely downward No Trend
Week 117: 01/07 - 01/20
* The Mann-Kendall (MK) trend test is a nonparametric test that evaluates whether there is a monotonic trend in a time-series dataset. We applied the MK trend test to smothed N/PMMoV data and used a 14-day lookback period from the last datapoint available. We interpreted positive values of the test statistic, tau, with p <= 0.005, p <= 0.05, and p <= 0.01 as upward, likely upward, and very likely upward trends, respectively. We interpreted negative tau values with p <= 0.005, p <= 0.05, and p <= 0.01 as downward, likely downward, and very likely downward trends, respectively.
Criteria: need at least three positive detections in the last 14 days to report a percent change.
Sporadic: Labeled as sporadic detections if the above criteria is not met, but there is at least 1 positive detection in the last 14 days.

Percent change (PC)

Percent change in the last 14 days
Virus Merced County Stanislaus County Yolo County
SARS-CoV-2 Very likely downward Very likely downward Very likely downward
Norovirus No Trend No Trend Very likely downward
Rotavirus Very likely downward Very likely downward Very likely downward
Hepatitis A Virus No Trend No Trend No Trend
Candida auris No Trend No Trend No Trend
Enterovirus D68 No Trend No Trend No Trend
RSV Very likely downward Very likely downward Likely downward
Influenza A No Trend No Trend No Trend
Influenza B Very likely downward No Trend No Trend
HMPV Very likely upward Likely downward Very likely downward
Parainfluenza Very likely downward Very likely downward Likely downward
Week 117: 01/07 - 01/20
* The slope is calculated from a least-squares linear regression of log10-transformed values of the N/PMMoV data versus day. We used a 14-day look-back period to calculate the slope. For each slope estimate, we extracted the 90%, 95%, and 99% confidence intervals (CIs) to calculate the 90%, 95%, and 99% CIs for each PC estimate. We interpreted PC values greater than 0 for the 90%, 95%, and 99% upper CIs as upward, likely upward, and very likely upward trends, respectively. We interpreted PC values less than 0 for the 90%, 95%, and 99% lower CIs as downward, likely downward, and very likely downward trends day and previous n - 1 days.
Criteria: need at least three positive detections in the last 14 days to report a percent change.
Sporadic: Labeled as sporadic detections if the above criteria is not met, but there is at least 1 positive detection in the last 14 days.

Relative Strength Index

The Relative Strength Index
Virus Merced County Stanislaus County Yolo County
SARS-CoV-2 No Trend No Trend Downward
Norovirus No Trend No Trend Downward
Rotavirus Downward No Trend No Trend
Hepatitis A Virus No Trend No Trend Very likely upward
Candida auris No Trend No Trend No Trend
Enterovirus D68 No Trend Very likely upward Very likely downward
RSV Downward No Trend No Trend
Influenza A No Trend No Trend No Trend
Influenza B Downward No Trend Downward
HMPV Upward No Trend No Trend
Parainfluenza Downward No Trend No Trend
Week 117: 01/07 - 01/20
* The Relative Strength Index (RSI) calculates a ratio of the recent upward price movements to the absolute price movement. Developed by J. Welles Wilder.
Criteria: need at least three positive detections in the last 14 days to report a percent change.
Sporadic: Labeled as sporadic detections if the above criteria is not met, but there is at least 1 positive detection in the last 14 days.

General Update at City Level

Percentage of change

Percent change
Virus Merced County Stanislaus County Yolo County
Merced Los Banos Modesto Turlock Davis Esparto Winters Woodland
SARS-CoV-2 0.7% 33% 56.3% 51.7% 27.6% 87.6% +43.8% 59.1%
Norovirus 43.5% 8.7% +64% 47.6% 32% 62.5% 76.8% 69.8%
Rotavirus 44.2% 75% 12.1% +38.2% +97.7% 91.5% +Sharply 44.5%
Hepatitis A Virus +190% ND ND ND ND ND ND ND
Candida auris ND ND ND ND ND ND ND NA
Enterovirus D68 ND ND ND ND ND ND ND ND
RSV +2.2% 72.2% 20.1% 16.3% +20.7% 89% 14.4% +40.4%
Influenza A NA NA NA NA NA NA 60.8% NA
Influenza B 54.5% +13.7% ND 86.2% 10.4% ND ND ND
HMPV +31.3% +194% ND +415% 52.3% +9% ND 74.1%
Parainfluenza 12.9% +107% +35.3% +27.5% 33.8% +156% 71.1% 40.5%
Percent change is calculated here using the average of measurements over the past two weeks compared to the average of measurements from the prior two weeks. Results below the limit of detection are included in the averages as half the limit of detection.
Criteria: need at least three positive detections in the last 14 days to report a percent change.
NA: if the above criteria is not met and there were no data available in the last 7 days.
Sporadic: Labeled as sporadic detections if the above criteria is not met, but there is at least 1 positive detection in the last 14 days.
ND: Non-detect (i.e., below the limit of detection) if there were no detections in the last 14 days.
+LL: increasing but at low levels. If the above criteria is met but there were no positive detections or no data in the prior 14 days.
+Sharply: percent change is greater than 500%.
Weeks 114-115: 12/24 - 01/06
Weeks 116-117: 01/07 - 01/20

Current wastewater level

Current wastewater level
Virus Merced County Stanislaus County Yolo County
Merced Los Banos Modesto Turlock Davis Esparto Winters Woodland
SARS-CoV-2 Medium High High Medium High Medium High High
Norovirus Low High High High Medium Low Low Medium
Rotavirus High Medium Medium Medium High High Low High
Hepatitis A Virus High Low Low Low Low Low Low Low
Candida auris Low Low Low Low Low Low Low Low
Enterovirus D68 Low Low Low Low Low Low Low Low
RSV High Low Low Medium Medium Low Medium High
Influenza A Low Medium Low Medium Medium Medium Low Low
Influenza B Low Low Low Low Low Low Low Low
HMPV Low Low Low Low Low Low Low Low
Parainfluenza Low Low Low Low Low Medium Low Low
If there have not been at least one positive sample in the last 7 days and at least three positive samples in the last 14 days, a low categorization is assigned.
For non-seasonal pathogens, the boundaries of the low, medium, and high labels are defined as the tertiles of all data available for that pathogen within a given site or county.
For seasonal pathogens, the boundaries of the low, medium, and high labels are defined as the thirds of the 95th percentile value for all of the data available for that pathogen within a given site or county.

Trend test at City level

Mann-Kendall trend test

Mann-Kendall trend test
Virus Merced County Stanislaus County Yolo County
Merced Los Banos Modesto Turlock Davis Esparto Winters Woodland
SARS-CoV-2 Very likely downward No Trend No Trend Very likely downward No Trend Very likely downward No Trend Very likely downward
Norovirus Very likely downward Likely upward Very likely upward No Trend Upward Likely downward Very likely downward Very likely downward
Rotavirus Very likely downward Very likely downward Likely downward Very likely downward Very likely upward Very likely downward Sporadic Downward
Hepatitis A Virus Very likely upward No Trend No Trend No Trend No Trend No Trend No Trend No Trend
Candida auris No Trend No Trend No Trend No Trend No Trend No Trend No Trend No Trend
Enterovirus D68 No Trend No Trend No Trend No Trend No Trend No Trend No Trend No Trend
RSV Very likely downward Very likely downward Sporadic Very likely downward No Trend Very likely downward Very likely upward No Trend
Influenza A No Trend Downward Sporadic No Trend No Trend Very likely downward Likely downward Sporadic
Influenza B Sporadic Sporadic No Trend Sporadic Sporadic No Trend No Trend No Trend
HMPV Very likely downward Very likely upward No Trend Sporadic Sporadic Sporadic No Trend No Trend
Parainfluenza Very likely downward Likely downward Sporadic Very likely downward No Trend Likely upward Sporadic Sporadic
Week 117: 01/07 - 01/20
* The Mann-Kendall (MK) trend test is a nonparametric test that evaluates whether there is a monotonic trend in a time-series dataset. We applied the MK trend test to smothed N/PMMoV data and used a 14-day lookback period from the last datapoint available. We interpreted positive values of the test statistic, tau, with p <= 0.005, p <= 0.05, and p <= 0.01 as upward, likely upward, and very likely upward trends, respectively. We interpreted negative tau values with p <= 0.005, p <= 0.05, and p <= 0.01 as downward, likely downward, and very likely downward trends, respectively.
Criteria: need at least three positive detections in the last 14 days to report a percent change.
Sporadic: Labeled as sporadic detections if the above criteria is not met, but there is at least 1 positive detection in the last 14 days.

Percent change (PC)

Percent change in the last 14 days
Virus Merced County Stanislaus County Yolo County
Merced Los Banos Modesto Turlock Davis Esparto Winters Woodland
SARS-CoV-2 Very likely downward No Trend No Trend Very likely downward Likely upward Very likely downward No Trend Likely downward
Norovirus Very likely downward Very likely upward Very likely upward No Trend Upward Very likely downward Very likely downward Likely downward
Rotavirus Very likely downward Very likely downward Likely downward Very likely downward Very likely upward Very likely downward Sporadic No Trend
Hepatitis A Virus Likely upward No Trend No Trend No Trend No Trend No Trend No Trend No Trend
Candida auris No Trend No Trend No Trend No Trend No Trend No Trend No Trend No Trend
Enterovirus D68 No Trend No Trend No Trend No Trend No Trend No Trend No Trend No Trend
RSV Very likely downward Very likely downward Sporadic Very likely downward No Trend Very likely downward Very likely upward No Trend
Influenza A No Trend Very likely downward Sporadic No Trend No Trend Very likely downward Very likely downward Sporadic
Influenza B Sporadic Sporadic No Trend Sporadic Sporadic No Trend No Trend No Trend
HMPV Very likely downward Very likely upward No Trend Sporadic Sporadic Sporadic No Trend No Trend
Parainfluenza Very likely downward No Trend Sporadic Very likely downward Upward Very likely upward Sporadic Sporadic
Week 117: 01/07 - 01/20
* The slope is calculated from a least-squares linear regression of log10-transformed values of the N/PMMoV data versus day. We used a 14-day look-back period to calculate the slope. For each slope estimate, we extracted the 90%, 95%, and 99% confidence intervals (CIs) to calculate the 90%, 95%, and 99% CIs for each PC estimate. We interpreted PC values greater than 0 for the 90%, 95%, and 99% upper CIs as upward, likely upward, and very likely upward trends, respectively. We interpreted PC values less than 0 for the 90%, 95%, and 99% lower CIs as downward, likely downward, and very likely downward trends day and previous n - 1 days.
Criteria: need at least three positive detections in the last 14 days to report a percent change.
Sporadic: Labeled as sporadic detections if the above criteria is not met, but there is at least 1 positive detection in the last 14 days.

Relative Strength Index

The Relative Strength Index
Virus Merced County Stanislaus County Yolo County
Merced Los Banos Modesto Turlock Davis Esparto Winters Woodland
SARS-CoV-2 No Trend No Trend No Trend No Trend No Trend Downward No Trend No Trend
Norovirus No Trend No Trend No Trend No Trend Downward No Trend No Trend No Trend
Rotavirus No Trend No Trend No Trend No Trend No Trend Downward Sporadic Upward
Hepatitis A Virus Very likely upward No Trend No Trend No Trend No Trend No Trend No Trend No Trend
Candida auris No Trend No Trend No Trend No Trend No Trend No Trend No Trend No Trend
Enterovirus D68 No Trend No Trend No Trend No Trend No Trend No Trend No Trend No Trend
RSV No Trend Downward Sporadic No Trend No Trend Downward No Trend Upward
Influenza A No Trend No Trend Sporadic No Trend No Trend No Trend No Trend Sporadic
Influenza B Sporadic Sporadic No Trend Sporadic Sporadic No Trend No Trend No Trend
HMPV No Trend Very likely upward No Trend Sporadic Sporadic Sporadic No Trend No Trend
Parainfluenza Downward No Trend Sporadic No Trend No Trend Upward Sporadic Sporadic
Week 117: 01/07 - 01/20
* The Relative Strength Index (RSI) calculates a ratio of the recent upward price movements to the absolute price movement. Developed by J. Welles Wilder.
Criteria: need at least three positive detections in the last 14 days to report a percent change.
Sporadic: Labeled as sporadic detections if the above criteria is not met, but there is at least 1 positive detection in the last 14 days.

Merced County

SARS-CoV-2

Merced’s average SARS-CoV-2 concentrations (N/PMMoV) remained the same 🔄 between the most recent two weeks and the two weeks prior to that. Los Banos’s average decreased ⬇️ by 33%.

Influenza A

Merced’s average Influenza A concentrations (Flu A/PMMoV) No data available between the most recent two weeks and the two weeks prior to that. Los Banos’ average No data available.

Influenza B

Merced’s average Influenza B concentrations (Flu B/PMMoV) decreased ⬇️ by 54.5% between the most recent two weeks and the two weeks prior to that. Los Banos’ average increased ⬆️ by 13.7%.

RSV

Merced’s average RSV concentrations (RSV/PMMoV) remained the same 🔄 between the most recent two weeks and the two weeks prior to that. Los Banos’ average decreased ⬇️ by 72.2%.

HMPV

Merced’s HMPV concentrations (HMPV/PMMoV) increased ⬆️ by 31.3% between the most recent two weeks and the two weeks prior to that. Los Banos’s average increased ⬆️ by 194%.

Norovirus

Merced’s average Norovirus concentrations (Norovirus/PMMoV) decreased ⬇️ by 43.5% between the most recent two weeks and the two weeks prior to that. Los Banos’ average decreased ⬇️ by 8.7%.

Hepatitis A Virus

Merced’s average Hepatitis A Virus concentrations (HAV/PMMoV) increased ⬆️ by 190% between the most recent two weeks and the two weeks prior to that. Los Banos’ average showed no detection.

Rotavirus

Merced’s average Rotavirus concentrations (Rotavirus/PMMoV) decreased ⬇️ by 44.2% between the most recent two weeks and the two weeks prior to that. Los Banos’ average decreased ⬇️ by 75%.

Enterovirus D68

Merced’s average Enterovirus D68 concentrations (EV_D68/PMMoV) showed no detection between the most recent two weeks and the two weeks prior to that. Los Banos’ average showed no detection.

Candida auris

Merced’s average Candida auris concentrations (C_auris/PMMoV) showed no detection between the most recent two weeks and the two weeks prior to that. Los Banos’ average showed no detection.

Parainfluenza

Merced’s average Parainfluenza concentrations (HPIV/PMMoV) decreased ⬇️ by 12.9% between the most recent two weeks and the two weeks prior to that. Los Banos’ average increased ⬆️ by 107%.

Stanislaus County

SARS-CoV-2

Modesto’s average SARS-CoV-2 concentrations (N/PMMoV) decreased ⬇️ by 56.3% between the most recent two weeks and the two weeks prior to that. Turlock’s average decreased ⬇️ by 51.7%.

Influenza A

Modesto’s average Influenza A concentrations (Flu A/PMMoV) No data available between the most recent two weeks and the two weeks prior to that. Turlock’s average No data available.

Influenza B

Modesto’s average Influenza B concentrations (Flu B/PMMoV) showed no detection between the most recent two weeks and the two weeks prior to that. Turlock’s average decreased ⬇️ by 86.2%.

RSV

Modesto’s average RSV concentrations (RSV/PMMoV) decreased ⬇️ by 20.1% between the most recent two weeks and the two weeks prior to that. Turlock’s average decreased ⬇️ by 16.3%.

HMPV

Modesto’s average HMPV concentrations (HMPV/PMMoV) showed no detection between the most recent two weeks and the two weeks prior to that. Turlock’s average increased ⬆️ by 415%.

Norovirus

Modesto’s average Norovirus concentrations (Norovirus/PMMoV) increased ⬆️ by 64% between the most recent two weeks and the two weeks prior to that. Turlock’s average decreased ⬇️ by 47.6%.

Hepatitis A Virus

Modesto’s average Hepatitis A Virus concentrations (HAV/PMMoV) showed no detection between the most recent two weeks and the two weeks prior to that. Turlock’s average showed no detection.

Rotavirus

Modesto’s average Rotavirus concentrations (Rotavirus/PMMoV) decreased ⬇️ by 12.1% between the most recent two weeks and the two weeks prior to that. Turlock’s average increased ⬆️ by 38.2%.

Enterovirus D68

Modesto’s average Enterovirus D68 concentrations (EV_D68/PMMoV) showed no detection between the most recent two weeks and the two weeks prior to that. Turlock’s average showed no detection.

Candida auris

Modesto’s average Candida auris concentrations (C_auris/PMMoV) showed no detection between the most recent two weeks and the two weeks prior to that. Turlock’s average showed no detection.

Parainfluenza

Modesto’s average Parainfluenza concentrations (HPIV/PMMoV) increased ⬆️ by 35.3% between the most recent two weeks and the two weeks prior to that. Turlock’s average increased ⬆️ by 27.5%.

Yolo County

SARS-CoV-2

Davis’ average SARS-CoV-2 concentrations (N/PMMoV) decreased ⬇️ by 27.6% between the most recent two weeks and the two weeks prior to that. Esparto’s average decreased ⬇️ by 87.6%. Winters’ average increased ⬆️ by 43.8%. Woodland’s average decreased ⬇️ by 59.1%.

Influenza A

Davis’ average Influenza A concentrations (Flu A/PMMoV) No data available between the most recent two weeks and the two weeks prior to that. Esparto’s average No data available. Winters’ average decreased ⬇️ by 60.8%. Woodland’s average No data available.

Influenza B

Davis’ average Influenza B concentrations (Flu B/PMMoV) decreased ⬇️ by 10.4% between the most recent two weeks and the two weeks prior to that. Esparto’s average showed no detection. Winters’ average showed no detection. Woodland’s average showed no detection.

RSV

Davis’ average RSV concentrations (RSV/PMMoV) increased ⬆️ by 20.7% between the most recent two weeks and the two weeks prior to that. Esparto’s average decreased ⬇️ by 89%. Winters’ average decreased ⬇️ by 14.4%. Woodland’s average increased ⬆️ by 40.4%.

HMPV

Davis’ HMPV concentrations (HMPV/PMMoV) decreased ⬇️ by 52.3% between the most recent two weeks and the two weeks prior to that. Esparto’s average increased ⬆️ by 9%. Winters’ average showed no detection. Woodland’s average decreased ⬇️ by 74.1%.

Norovirus

Davis’ Norovirus concentrations (Norovirus/PMMoV) decreased ⬇️ by 32% between the most recent two weeks and the two weeks prior to that. Esparto’s average decreased ⬇️ by 62.5%. Winters’ average decreased ⬇️ by 76.8%. Woodland’s average decreased ⬇️ by 69.8%.

Hepatitis A Virus

Davis’ Hepatitis A Virus concentrations (HAV/PMMoV) showed no detection between the most recent two weeks and the two weeks prior to that. Esparto’s average showed no detection. Winters’ average showed no detection. Woodland’s average showed no detection.

Rotavirus

Davis’ Rotavirus concentrations (Rotavirus/PMMoV) increased ⬆️ by 97.7% between the most recent two weeks and the two weeks prior to that. Esparto’s average decreased ⬇️ by 91.5%. Winters’ average increased ⬆️ sharply. Woodland’s average decreased ⬇️ by 44.5%.

Enterovirus D68

Davis’ Enterovirus D68 concentrations (EV_D68/PMMoV) showed no detection between the most recent two weeks and the two weeks prior to that. Esparto’s average showed no detection. Winters’ average showed no detection. Woodland’s average showed no detection.

Candida auris

Davis’ Candida auris concentrations (C_auris/PMMoV) showed no detection between the most recent two weeks and the two weeks prior to that. Esparto’s average showed no detection. Winters’ average showed no detection. Woodland’s average No data available.

Parainfluenza

Davis’ Parainfluenza concentrations (HPIV/PMMoV) decreased ⬇️ by 33.8% between the most recent two weeks and the two weeks prior to that. Esparto’s average increased ⬆️ by 156%. Winters’ average decreased ⬇️ by 71.1%. Woodland’s average decreased ⬇️ by 40.5%.

All Counties

Mpox Update

Davis’ average Mpox concentrations (Mpox/PMMoV) No data available between the most recent two weeks and the two weeks prior to that. Esparto’s average No data available. Winters’ average No data available. Woodland’s average No data available. Merced’s average No data available. Los Banos’ average No data available. Modesto’s average No data available. Turlock’s average No data available https://healthycvtogether.org/monkeypox-data/