Environmental surveillance of poliovirus in Guatemala

What is Poliomyelitis?

Poliomyelitis, commonly known as polio, is a highly contagious, vaccine preventable disease caused by the poliovirus, which can lead to paralysis in children under 15 years of age.  In Guatemala, both the inactivated poliovirus vaccine (IPV) and the oral poliovirus vaccine (OPV) are administered.

The last confirmed case of wild poliovirus-induced poliomyelitis in Guatemala was recorded in 1990, and in the Americas region in 1991. In 1994, the region was certified poliovirus-free.

Despite efforts to eradicate it, some countries still report cases of children with permanent paralysis as a result of this disease.

What is Environmental Surveillance?

Environmental surveillance for poliovirus is a surveillance strategy that involves the collection and analysis of samples of wastewater or water from other environments to detect the presence of poliovirus.

This is complementary to epidemiological surveillance of acute flaccid paralysis (AFP) cases, helping to identify virus circulation in the community before clinical cases appear.

Why and since when is it performed in Guatemala?

In 2014, The PAHO Technical Advisory Group recommended the implementation of wastewater-based environmental surveillance to ensure the timely implementation of relevant control measures.

According to the risk assessment for reintroduction and circulation of poliovirus in the Americas region, conducted by the Regional Certification Commission, in 2018 Guatemala was classified as high-risk. This was due to the country’s vaccination coverage and surveillance system, as well as information on recent epidemic outbreaks, basic services, and other related indicators.

In response, the Ministry of Public Health and Social Assistance of Guatemala initiated environmental surveillance in November 2018.

Where is environmental surveillance conducted?

Environmental surveillance of poliovirus is implemented in two urban areas: San Juan Sacatepéquez and Villa Nueva. Three different sampling sites are selected in each municipality.

The selection of these municipalities and sites was based on population density, OPV3 vaccination coverage (2014-2017), surveillance indicators, and basic sanitation conditions.

What is the process?

Field visits to the three sampling sites in each of the two municipalities are conducted once a month, from 7:00 a.m. to 9:00 a.m., when the population contributes most biological waste to the sampling sites. Two bottles, each containing one liter of untreated wastewater, are collected at each selected sampling site.

The process is as follows:

Verification of the sampling site, surrounding area, and confirmation that it is safe to obtain samples.

Verification of the container from which the sample is obtained and its labeling (sample code, date, time, and collector's initials).

Completion of the "wastewater collection form" with collector information, date and time of collection, sample code, weather conditions at the site the previous day and on the day of sample collection.

The wastewater sampling process is performed by gently submerging a bucket into the wastewater so that the water flows into it. The collected water is then poured into the sample storage container.

The container is disinfected after pouring the water sample.

The temperature of the sample is taken and recorded on the form.

The container with the sample is sealed with Parafilm and stored in a plastic bag with a tight seal, and finally placed in a thermal box (cooler) at a temperature between +2 and +8°C.

This same process is repeated at the other sampling sites.

After completing the sampling, the containers with the are transported to the National Health Laboratory Directorate of the Ministry of Public Health and Social Assistance, Guatemala. 

The samples are delivered to the reception area of the National Health Laboratory Directorate where the condition of the samples is verified, and the temperature is recorded and documented on the form. 

Receipt of samples at the National Health Laboratory Directorate of the Ministry of Public Health and Social Assistance, Guatemala.

After registration at the laboratory, the samples are sent to virology, where they are stored at -20°C until they are sent by international courier to the Poliovirus and Picornavirus Laboratory (PPLB) at the Centers for Disease Control and Prevention (CDC) in the United States, Atlanta. This is funded thanks to support from PAHO/WHO.

The shipment follows the International Air Transport Association (IATA) regulations for the safe transport of infectious substances.

At the CDC's Poliovirus and Picornavirus Laboratory samples are processed using standardized methods of the WHO Global Polio Laboratory Network.

Results are then communicated to PAHO and the Ministry of Public Health and Social Assistance of Guatemala, who analyze them and take action accordingly.

PAHO Support

PAHO/WHO provides technical and financial support for poliovirus environmental surveillance in Guatemala. This support includes risk analysis, site selection for sampling, and the development of implementation protocols.