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

  • Weeks 101-102: 09/24 - 10/07
  • Weeks 103-104: 10/08 - 10/21

General Update at County Level

For each county, the aggregated trend is population-weighted. It is calculated using the 10-days 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 sites.

Table: Percentage of change

Percent change
Virus Merced County Stanislaus County Yolo County
SARS-CoV-2 83% 89.6% 50.4%
Influenza A 77.4% ND 71.3%
Influenza B 83% 89.6% 50.4%
RSV 92% ND 97.1%
HMPV ND ND +706.3%
Norovirus 71.3% 61.9% 59%
Hepatitis A Virus ND ND ND
Human Adenovirus Group F 77.7% 72.4% 85.7%
Rotavirus 89% 24.3% 34.7%
Enterovirus D86 ND ND ND
Candida auris ND ND ND
Parainfluenza 69% +63% +29.4%
Percent change is calculated here using average of measurements over the past two weeks compared to the average of measurements from the prior two weeks.
ND- Non-detect (below detection limit)
+LL increasing but at low levels
Weeks 101-102: 09/24 - 10/07
Weeks 103-104: 10/08 - 10/21

Current wastewater level

Current wastewater level
Virus Merced County Stanislaus County Yolo County
SARS-CoV-2 Low Low Medium
Influenza A Medium Low Medium
Influenza B Low Low Medium
RSV High Low Low
HMPV Low Low Medium
Norovirus Low Low Low
Hepatitis A Virus Low Low Low
Human Adenovirus Group F High High High
Rotavirus High High High
Enterovirus D86 Low Low Low
Candida auris Low Low Low
Parainfluenza High High High
The current wastewater levels are estimated using the 10-day rolling average (10-d.m.a). The 33rd and 66th percentiles are calculated over the past 365 days before 14 days ago. For counties with less than 365 days, all days before 14 days ago are used. The current wastewater level is classified as:
• Low: The current 10-dma is below 33rd percentile
• Medium: The current 10-dma is between the 33rd and 66th percentile
• High: The current 10-dma is above 66th Percentile

Trend test at county level

Relative Strength Index

The Relative Strength Index
Virus Merced County Stanislaus County Yolo County
SARS-CoV-2 Very likely downward Very likely downward Likely downward
Influenza A Very likely downward No Trend Very likely downward
Influenza B Very likely downward Very likely downward Likely downward
RSV Very likely downward Likely downward Very likely downward
HMPV Very likely downward No Data No Trend
Norovirus Likely downward Very likely downward Very likely downward
Hepatitis A Virus No Data No Data No Data
Human Adenovirus Group F Downward Very likely downward Very likely downward
Rotavirus Very likely downward Downward Downward
Enterovirus D86 No Data No Data Very likely downward
Candida auris No Data No Data No Data
Parainfluenza Likely downward No Trend No Trend
Week 104: 10/08 - 10/21
* The Relative Strength Index (RSI) calculates a ratio of the recent upward price movements to the absolute price movement. Developed by J. Welles Wilder.

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
Influenza A Very likely downward Very likely downward Likely downward
Influenza B Very likely downward Very likely downward Very likely downward
RSV Very likely downward Very likely downward Very likely downward
HMPV No Data No Data No Trend
Norovirus Very likely downward Very likely downward Very likely downward
Hepatitis A Virus No Data No Data No Data
Human Adenovirus Group F Very likely downward Very likely downward Very likely downward
Rotavirus Very likely downward Very likely downward Very likely downward
Enterovirus D86 No Data No Data Very likely downward
Candida auris No Data No Data No Data
Parainfluenza Very likely downward Very likely downward Very likely downward
Week 104: 10/08 - 10/21
* 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 raw N/PMMoV data and used a 14-day lookback period. We interpreted positive values of the test statistic, tau (τ), with p ≤ 0.1, p ≤ 0.05, and p ≤ 0.01 as upward, likely upward, and very likely upward trends, respectively. We interpreted negative τ values with p ≤ 0.1, p ≤ 0.05, and p ≤ 0.01 as downward, likely downward, and very likely downward trends, respectively.

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
Influenza A Very likely downward Very likely downward Downward
Influenza B Very likely downward Very likely downward Very likely downward
RSV Very likely downward Very likely downward Very likely downward
HMPV No Trend No Trend Likely downward
Norovirus Very likely downward Likely downward Likely downward
Hepatitis A Virus No Trend No Trend No Trend
Human Adenovirus Group F Very likely downward Very likely downward Very likely downward
Rotavirus Very likely downward Likely downward Likely downward
Enterovirus D86 No Trend No Trend Very likely downward
Candida auris No Trend No Trend No Trend
Parainfluenza Very likely downward Likely downward Likely downward
Week 104: 10/08 - 10/21
* 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.

Trend and effective reproductive number at county level

The embedded graph shows the effective reproductive number, Rt, which is the expected number of new infections caused by a single infectious person where some individuals may no longer be susceptible. It used to assess whether the epidemic is growing (>1), shrinking (<1), or holding steady (~1). To compute Rt from wastewater data, we utilize a proxy of the cases derived from the smoothed SARS-CoV-2 RNA concentration. The process involves dividing the smoothed concentration by the minimum concentration observed in the treatment plant. This normalization step ensures that the minimum concentration corresponds to a value of \(1\), serving as a reference point. Next, we multiply the normalized concentration by a scalar value, k; which we set as 3,1,3 for Merced, Stanislaus, and Yolo, respectively. This assumption implies that the minimum concentration observed in the treatment plant corresponds to approximately 4 infected individuals. The choice of k is not critical for calculating since it is scale-free.

The formula for computing the proxy of cases from wastewater data is as follows: \[I_{ww}= k \frac{C_{RNA}}{min {(C_{RNA})}}\] where \(C_{RNA} = (C_1,\ldots,C_n)\) represents the smoothed concentration vector at different time points. By applying this formula, we obtain a proxy of the cases based on the wastewater data.

Merced County

Stanislaus County

Yolo County

General Update at City Level

Table: Percentage of change

Percent change
Virus Merced County Stanislaus County Yolo County
Merced Los Banos Modesto Turlock Davis Esparto Winters Woodland
SARS-CoV-2 9.9% +12.4% 92.2% 19.4% 16.5% +45.1% +217.7% 3.2%
Influenza A +58.4% +37.6% ND ND ND ND ND +LL
Influenza B ND ND ND +LL ND ND ND ND
RSV 74.3% +133.2% ND ND 87.1% ND ND ND
HMPV ND +LL ND ND ND ND ND +LL
Norovirus +165.8% +225.5% 27.5% 26.5% +79.1% +156% 43.8% 28.6%
Hepatitis A Virus ND ND ND ND ND ND ND ND
Human Adenovirus Group F 36.3% 53.5% 50.8% 41.7% 85.5% +103.5% ND 75.2%
Rotavirus +105.1% 70.9% 22% 64.8% 76.6% ND ND +590.6%
Enterovirus D86 ND ND +LL ND ND ND ND ND
Candida auris ND ND ND ND ND ND ND ND
Parainfluenza +150.8% +685.7% +198.3% 47.1% 31% 1.2% +32.1% +1949.6%
Percent change is calculated here using average of measurements over the past two weeks compared to the average of measurements from the prior two weeks.
ND- Non-detect (below detection limit)
+LL increasing but at low levels
Weeks 101-102: 09/24 - 10/07
Weeks 103-104: 10/08 - 10/21

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 Low Medium Low Low High Low Medium Medium
Influenza A High High Low Low Low Low Low High
Influenza B Low Low Low High Low Low Low Low
RSV High Medium Low Low Low Low Low Low
HMPV Low Medium Low Low Low Low Low High
Norovirus Medium Low Low Low Low Medium Low Low
Hepatitis A Virus Low Low Low High Low Low Low Low
Human Adenovirus Group F High High Low Low Low Medium Low Low
Rotavirus Low Low High High Low Low Low High
Enterovirus D86 Low Low High Low Low Low Low High
Candida auris Low Low Low Low Low Low Low Low
Parainfluenza High High High High High High High NA
The current wastewater levels are estimated using the 10-day rolling average (10-d.m.a). The 33rd and 66th percentiles are calculated over the past 365 days before 14 days ago. For cities with less than 365 days, all days before 14 days ago are used. The current wastewater level is classified as:
• Low: The current 10-dma is below 33rd percentile
• Medium: The current 10-dma is between the 33rd and 66th percentile
• High: The current 10-dma is above 66th Percentile

Tab: Trend test at city level

Table 1: 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 upward No Trend Upward No Trend No Trend No Trend Very likely upward Very likely upward
Influenza A Very likely upward No Trend Very likely downward No Trend No Trend No Trend No Trend Upward
Influenza B No Trend No Trend No Trend No Trend No Trend No Trend No Trend No Trend
RSV Likely downward No Trend Very likely downward No Trend Likely downward No Trend No Trend No Trend
HMPV No Trend No Trend No Trend No Trend No Trend No Trend No Trend Very likely upward
Norovirus Very likely upward Very likely upward Likely downward No Trend Very likely upward Very likely downward No Trend No Trend
Hepatitis A Virus No Trend No Trend No Trend No Trend No Trend No Trend No Trend No Trend
Human Adenovirus Group F Very likely downward No Trend Very likely downward Very likely downward Very likely downward No Trend No Trend Very likely downward
Rotavirus No Trend Downward No Trend No Trend Very likely downward No Trend No Trend Very likely upward
Enterovirus D86 No Trend No Trend Upward 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
Parainfluenza Very likely upward Very likely upward No Trend No Trend Very likely downward No Trend Very likely downward Very likely upward
Week 104: 10/08 - 10/21
* 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.

Table 2: 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 Upward No Trend Upward No Trend No Trend Upward No Data
Influenza A Likely upward No Trend No Trend No Data No Trend No Data No Data No Data
Influenza B No Data No Data No Data No Data No Data No Data No Data No Data
RSV No Trend Very likely upward No Trend Downward No Trend No Data No Trend No Data
HMPV Very likely downward Very likely upward No Data No Data No Data No Data No Data No Data
Norovirus Likely upward Very likely upward Downward No Trend Very likely upward No Trend No Trend No Data
Hepatitis A Virus No Data No Data No Data No Data No Data No Data No Data No Data
Human Adenovirus Group F No Trend No Trend No Trend No Trend No Trend No Trend No Data No Data
Rotavirus No Trend No Trend No Trend Upward No Trend No Data No Trend No Data
Enterovirus D86 No Data No Data Very likely upward No Data No Data No Data No Data No Data
Candida auris No Data No Data No Data No Data No Data No Data No Data No Data
Parainfluenza No Trend No Trend No Trend No Trend No Trend No Trend No Trend No Data
Week 104: 10/08 - 10/21
* The Relative Strength Index (RSI) calculates a ratio of the recent upward price movements to the absolute price movement. Developed by J. Welles Wilder.

Table 3: 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 Likely upward No Trend Very likely upward No Trend No Trend No Trend No Trend Very likely upward
Influenza A Very likely upward No Trend Very likely downward No Data No Data No Data No Data Very likely upward
Influenza B No Data No Data No Data No Data No Data No Data No Data No Data
RSV Downward Likely upward Very likely downward No Trend Likely downward No Data No Trend No Data
HMPV No Data Likely upward No Data No Data No Data No Data No Data Very likely upward
Norovirus Very likely upward Very likely upward Very likely downward No Trend Very likely upward Very likely downward No Trend No Trend
Hepatitis A Virus No Data No Data No Data No Data No Data No Data No Data No Data
Human Adenovirus Group F Very likely downward No Trend Likely downward Very likely downward Very likely downward No Trend No Data Very likely downward
Rotavirus No Trend No Trend No Trend No Trend Very likely downward No Data Likely downward Very likely upward
Enterovirus D86 No Data No Data Very likely upward No Data No Data No Data No Data No Trend
Candida auris No Data No Data No Data No Data No Data No Data No Data No Data
Parainfluenza Very likely upward Very likely upward No Trend Downward Very likely downward No Trend Very likely downward Very likely upward
Week 104: 10/08 - 10/21
* 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 raw N/PMMoV data and used a 14-day lookback period. We interpreted positive values of the test statistic, tau (τ), with p ≤ 0.1, p ≤ 0.05, and p ≤ 0.01 as upward, likely upward, and very likely upward trends, respectively. We interpreted negative τ values with p ≤ 0.1, p ≤ 0.05, and p ≤ 0.01 as downward, likely downward, and very likely downward trends, respectively.

Merced County

SARS-CoV-2

Merced’s average SARS-CoV-2 concentrations (N/PMMoV) decreased ⬇️ by 9.9% between the most recent two weeks and the two weeks prior to that. Los Banos’ average increased ⬆️ by 12.4%.

Fig 1. Merced

Fig 2. Los Banos

Influenza A

Merced’s average Influenza A concentrations (Flu A/PMMoV) increased ⬆️ by 58.4% between the most recent two weeks and the two weeks prior to that. Los Banos’ average increased ⬆️ by 37.6%.

Influenza B

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

RSV

Merced’s average RSV concentrations (RSV/PMMoV) decreased ⬇️ by 74.3% between the most recent two weeks and the two weeks prior to that. Los Banos’ average increased ⬆️ by 133.2%.

HMPV

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

Norovirus

Merced’s average Norovirus concentrations (Norovirus/PMMoV) increased ⬆️ by 165.8% between the most recent two weeks and the two weeks prior to that. Los Banos’ average increased ⬆️ by 225.5%.

Stanislaus County

SARS-CoV-2

Modesto’s average SARS-CoV-2 concentrations (N/PMMoV) decreased ⬇️ by 92.2% between the most recent two weeks and the two weeks prior to that. Turlock’s average decreased ⬇️ by 19.4%.

Fig 1. Modesto

Fig 2. Turlock

Influenza A

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

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 +LL.

RSV

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

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 showed no detection.

Norovirus

Modesto’s average Norovirus concentrations (Norovirus/PMMoV) decreased ⬇️ by 27.5% between the most recent two weeks and the two weeks prior to that. Turlock’s average decreased ⬇️ by 26.5%.

Yolo County

SARS-CoV-2

Davis’ average SARS-CoV-2 concentrations (N/PMMoV) decreased ⬇️ by 16.5% between the most recent two weeks and the two weeks prior to that. Esparto’s average increased ⬆️ by 45.1%. Winters’ average increased ⬆️ by 217.7%. Woodland’s average remained the same 🔄.

Fig 1. Davis

Fig 2. Esparto

Fig 3. Winters

Fig 4. Woodland

Influenza A

Davis’ average Influenza A concentrations (Flu A/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 +LL.

Influenza B

Davis’ average Influenza B concentrations (Flu B/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.

RSV

Davis’ average RSV concentrations (RSV/PMMoV) decreased ⬇️ by 87.1% 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.

HMPV

Davis’ HMPV concentrations (HMPV/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 +LL.

Norovirus

Davis’ Norovirus concentrations (Norovirus/PMMoV) increased ⬆️ by 79.1% between the most recent two weeks and the two weeks prior to that. Esparto’s average increased ⬆️ by 156%. Winters’ average decreased ⬇️ by 43.8%. Woodland’s average decreased ⬇️ by 28.6%.

All Counties

Mpox Update

There are no detections for samples taken at our plants from the last two weeks. https://healthycvtogether.org/monkeypox-data/