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

  • Weeks 97-98: 08/27 - 09/09
  • Weeks 99-100: 09/10 - 09/23

General Update at County Level

Table: Percentage of change

Percent change
Virus Merced County Stanislaus County Yolo County
SARS-CoV-2 19% 5% 24%
Influenza A 15% ND +391%
Influenza B ND ND ND
RSV +8% +355% 47%
HMPV +LL 89% +522%
Norovirus +1% +48% 11%
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 97-98: 08/27 - 09/09
Weeks 99-100: 09/10 - 09/23

Current wastewater level

For each county, the concentrations obtained from each sampling location within the county were aggregated using a weighted average (weighted by sewershed population).

Current wastewater level
Virus Merced County Stanislaus County Yolo County
SARS-CoV-2 Medium High Medium
Influenza A Medium Low Medium
Influenza B Low Low Low
RSV Medium Medium Medium
HMPV Low Low Low
Norovirus Low Low Low
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 No Trend No Trend Likely downward
Influenza A No Trend No Data Likely upward
Influenza B No Data No Data No Data
RSV No Trend No Trend Downward
HMPV Very likely upward Very likely downward Likely upward
Norovirus No Trend No Trend Downward
Week 100: 09/10 - 09/23
* 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 upward Upward
Influenza A Very likely downward No Data Very likely upward
Influenza B No Data No Data No Data
RSV Likely upward No Trend Downward
HMPV Very likely upward Very likely downward Very likely upward
Norovirus No Trend No Trend Very likely downward
Week 100: 09/10 - 09/23
* 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 upward Very likely upward
Influenza A Very likely downward No Trend Very likely upward
Influenza B No Trend No Trend No Trend
RSV Very likely upward No Trend No Trend
HMPV Very likely upward Very likely downward Very likely upward
Norovirus No Trend No Trend Very likely downward
Week 100: 09/10 - 09/23
* 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

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 32% 72% +10% +10% 32% +78% +41% +52%
Influenza A 100% +LL ND ND +444% ND ND +LL
Influenza B ND ND ND ND ND ND ND ND
RSV +223% +LL ND 100% +90% 100% +LL ND
HMPV +LL ND ND +21% +LL +LL ND +LL
Norovirus 28% 14% 17% 38% 38% 67% +252% +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 97-98: 08/27 - 09/09
Weeks 99-100: 09/10 - 09/23

Tab: Trend test at city level

Table 1: Percent change (PC)

Percent change in the last 14 days
Virus Merced Los Banos Modesto Turlock Davis Esparto Winters Woodland
SARS-CoV-2 Very likely downward No Trend No Trend Downward Very likely downward Very likely upward Very likely upward No Trend
Influenza A Downward No Trend No Trend No Trend Very likely upward No Trend No Trend No Trend
Influenza B No Trend No Trend No Trend No Trend No Trend No Trend No Trend No Trend
RSV Likely upward No Trend No Trend No Trend Upward No Trend No Trend No Trend
HMPV No Trend No Trend No Trend No Trend Upward No Trend No Trend No Trend
Norovirus Very likely downward Upward Likely upward Very likely downward Very likely downward Very likely downward Very likely upward Very likely upward
Week 100: 09/10 - 09/23
* 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 Los Banos Modesto Turlock Davis Esparto Winters Woodland
SARS-CoV-2 No Trend No Trend No Trend No Trend No Trend No Trend No Trend No Trend
Influenza A No Trend Very likely upward No Data No Data Very likely upward 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 Upward No Data No Data No Data No Trend No Trend No Trend No Data
HMPV No Data No Data No Data No Data Upward No Data No Data No Data
Norovirus Downward No Trend No Trend No Trend No Trend No Trend Very likely upward No Trend
Week 100: 09/10 - 09/23
* 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 Los Banos Modesto Turlock Davis Esparto Winters Woodland
SARS-CoV-2 Very likely downward No Trend No Trend No Trend Very likely downward Very likely upward Upward No Trend
Influenza A Very likely downward Likely upward No Data No Data Very likely upward 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 Very likely upward No Data No Data No Data Upward No Data No Trend No Data
HMPV No Data No Data No Data No Data Very likely upward No Data No Data No Data
Norovirus Very likely downward Upward No Trend Likely downward Very likely downward Downward Very likely upward Likely upward
Week 100: 09/10 - 09/23
* 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 32% between the most recent two weeks and the two weeks prior to that. Los Banos’ average decreased ⬇️ by 72%.

Fig 1. Merced

Fig 2. Los Banos

Influenza A

Merced’s average Influenza A concentrations (Flu A/PMMoV) decreased ⬇️ by 100% between the most recent two weeks and the two weeks prior to that. Los Banos’ average increased ⬆️ by 100%.

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) increased ⬆️ by 223% between the most recent two weeks and the two weeks prior to that. Los Banos’ average increased ⬆️ by 100%.

HMPV

Merced’s HMPV concentrations (HMPV/PMMoV) increased ⬆️ by 100% between the most recent two weeks and the two weeks prior to that. Los Banos’s average showed no detection.

Norovirus

Merced’s average Norovirus concentrations (Norovirus/PMMoV) decreased ⬇️ by 28% between the most recent two weeks and the two weeks prior to that. Los Banos’ average decreased ⬇️ by 14%.

Stanislaus County

SARS-CoV-2

Modesto’s average SARS-CoV-2 concentrations (N/PMMoV) increased ⬆️ by 10% between the most recent two weeks and the two weeks prior to that. Turlock’s average increased ⬆️ by 10%.

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 showed no detection.

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 decreased ⬇️ by 100%.

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 21%.

Norovirus

Modesto’s average Norovirus concentrations (Norovirus/PMMoV) decreased ⬇️ by 17% between the most recent two weeks and the two weeks prior to that. Turlock’s average decreased ⬇️ by 38%.

Yolo County

SARS-CoV-2

Davis’ average SARS-CoV-2 concentrations (N/PMMoV) decreased ⬇️ by 32% between the most recent two weeks and the two weeks prior to that. Esparto’s average increased ⬆️ by 78%. Winters’ average increased ⬆️ by 41%. Woodland’s average increased ⬆️ by 52%.

Fig 1. Davis

Fig 2. Esparto

Fig 3. Winters

Fig 4. Woodland

Influenza A

Davis’ average Influenza A concentrations (Flu A/PMMoV) increased ⬆️ by 444% 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 increased ⬆️ by 100%.

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) increased ⬆️ by 90% between the most recent two weeks and the two weeks prior to that. Esparto’s average decreased ⬇️ by 100%. Winters’ average increased ⬆️ by 100%. Woodland’s average showed no detection.

HMPV

Davis’ HMPV concentrations (HMPV/PMMoV) increased ⬆️ by 100% between the most recent two weeks and the two weeks prior to that. Esparto’s average increased ⬆️ by 100%. Winters’ average showed no detection. Woodland’s average increased ⬆️ by 100%.

Norovirus

Davis’ Norovirus concentrations (Norovirus/PMMoV) decreased ⬇️ by 38% between the most recent two weeks and the two weeks prior to that. Esparto’s average decreased ⬇️ by 67%. Winters’ average increased ⬆️ by 252%. Woodland’s average increased ⬆️ by 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/