Microbial Quality and Safety of Well Water in Rural Nicaragua as Determined by

Low Cost Bacterial Test

Patricia Weiss1, Tiong Gim Aw2, Joan B. Rose2

1School of Public Health, College of Human Medicine, Michigan State University, East Lansing, Michigan, 48824, United States.

2Department of Fisheries and Wildlife, 3 Natural Resources, Michigan State University, East Lansing, Michigan, 48824, United States.

Introduction783 million people lack access to safe water

(United Nations, 2013)2.5 billion people do not have improved

sanitation (United Nations, 2013)1.1 billion practice open defecation (World

Health Organization, 2010)Most of these people live in rural villages

such as Pueblo Nuevo, Nicaragua

Objectives of StudyTest microbial water quality of hand dug

wells in Pueblo Nuevo, NicaraguaDetermine Sources of Contamination

Background on Nicaragua1979 opposition to governmental manipulation—Marxist

Sandinistas came into power (Central Intelligence Agency, n.d.)

1988 hurricane Joan caused more damage to infrastructure and economy (Central Intelligence Agency, n.d.).

About 50% have access to improved sanitation (63% in urban areas and 37% in rural areas) (Central Intelligence Agency, n.d.)

20% without safe drinking water in Latin America (Pearce-Oroz, 2011)

Government is slowly improving access to water and sanitation (Social Investments Funds)

LocationPueblo Nuevo is located on the Caribbean

Coast

Cases of Illness in Pueblo Nuevo2012

• Water-related Diarrhea: 5,675 Cases

• Parasites: 2,850 Cases• Pneumonia: 47 Cases• Respiratory Infections: 8,750 Cases• Injuries due to Weapons: 467 Cases• Pregnancy Issues: 272 Cases

*Provided by Dr.Alejandro Picado

Types of Wells Sampled

Rope Pump Well Simple Well

Location of Wells

MethodsCompartment Bag Test (CBT) – E.coli Membrane Filtration & qPCR –

Microbial source tracking markers: B.theta (human), M2/M3 (bovine)

E. coli, enterococci

Compartment Bag Test

Compartment Bag Test8 key steps to perform CBT

1. Prepare dilutions2. Collect and record3. Mix water sample with growth medium4. Open and fill CBT5. Seal6. Incubate7. Score and record results on data sheets8. MPN chart for quality rating

Last Step: Decontamination• Each bucket=13.4L• 5 ml bleach per bucket• Put rope etc. in bucket

for at least half hour• 0.05g Sodium

Thiosulfate

Membrane FiltrationFiltered 1.4-1.8L of well water

DNA Extraction and qPCRDNA extracted using QIAamp DNA mini kit

(Qiagen) Platform used: Roche LightCycler ® 480 Real-Time PCR

System with 96 well block

Results and DiscussionResults of Compartment Bag Test and qPCR

Compartment Bag Test Results32 wells total87.5% of wells contaminated with E. coliContamination ranged from 3-404.5

MPN/100 mlGeometric mean 25.8/100 ml

Comprehensive Water Quality Rating

Average MPN of E. coli Relative to Depth and Elevation

0 10 20 30 40 50 60 70 800

50100150200250300350400450

f(x) = − 0.915737805094682 x + 60.3592734394429R² = 0.0215719759203369

Depth of Wells

Depth

Average MPN

15 20 25 30 35 40 45 500

50100150200250300350400450

f(x) = 0.471592321116928 x + 36.5689661431065R² = 0.00174700785160087

Elevation of Wells

Elevation

AverageMPN

Comparison of E. coli MPN between simple and rope-pump wells

Geometric Mean

t-Test, t=0.88, p = 0.19

Log-transformed t-Testt=-2.11, p = 0.02

64.1% Reduction in E. coli

*Used MPN of 3 for lower confidence interval

simple rope-pump 34.37 12.34

Similar to results seen in Gorter et al. (1998)—Using geometric mean overall 47% reduction of fecal coliforms seen in rope-pumps.

qPCR detection of molecular markers (No. sample tested: 31)

Conclusion• Generally the well water was deemed

unsafe in this small rural area in Nicaragua. • The CBT made it possible to test in the

field for E.coli contamination in a rural location where supplies and lab equipment was limited.

• qPCR analysis indicated bovine fecal pollution in the well water samples.

AcknowledgementMichigan State University School of Public Health

and College of Human MedicineThanks to Mark Sobsey for helping with Bag Test Regina Weiss, Sammia Forbes, Ashley Hodges,

guide Don Tito, Director Don Miguel, and Dr.Alejandro Picado

Fundacion para la Autonomia y el Desarollo De la Costa Atlantica de Nicaragua (FADCANIC)

Questions?