Ecology

The Ecology team of the Lassa Fever Program at the Kenema Government Hospital contribute valuable skills and services to the research being conducted into Lassa Fever by collaborators in the West. Mastomys natalensis, the rodent reservoir of the Lassa virus, are ever-present in the rural areas of Sierra Leone. Together with researchers, the Ecology team have worked on a series of projects including studies exploring the environmental risk factors impacting rodent infestation and the spread of the Lassa virus, recolonization studies, as well as working closely with the Lassa Outreach team in their contact tracing efforts.

The Ecology team is currently a three man team. Kandeh Kargbo and James Koninga both have over 30 years of field experience, while Willie Robert joined the team in 1998. Their job is not for the faint hearted. Firstly their work requires them to handle rodents carrying a killer virus, and despite the extensive personal protective measures that they undertake, there is little room for human error. Secondly they face logistical challenges related to poor road conditions in the field, as well as having to transport heavy equipment into remote locations, some of which are inaccessible by vehicle.

Since becoming involved in ecology, in the late 1970s, Kandeh Kargbo and James Koninga have worked on studies conducted by numerous institutions including the Center for Disease Control and Prevention, Colorado State University, University of New Mexico and Tulane University. In the late seventies and early eighties they also trapped animals for the National Museum of Natural History in Washington DC. Their work has taken them to the Democratic Republic of Congo where they collected samples from all animals during the Ebola outbreak of 1995. In Tanzania they worked on an integrated pest control management project.

Rodent trapping is physically demanding and requires long hours in the field. When collecting samples from rodents in the field, the team members wear protective clothing including gowns, shoe covers, masks and gloves that prevent them from contracting the deadly virus from its hosts. The Sherman traps (shown here on the left) are used to capture the rats and the GPS coordinates of each trap are noted allowing the team to pinpoint the exact location of each trap. Since Mastomys are most active at night, traps are set in the evening between 4 and 5 PM and are baited with oats, ground nut paste (peanut butter), palm oil and dried fish. Each trap is then checked in the morning starting at sunrise. Depending on the research being conducted the catch are processed, samples are taken (whole blood, spleen and/or liver depending on the study), the anatomy of the rodent is documented, the traps and all equipment used to handle and dissect rodents are disinfected, and the traps are set again in the evening. If the study requires it, this process is repeated several times to ensure that as many rodents as possible in a specific area are captured. The rodents have a short gestation period of only 30 days and can produce more than 14 offspring per litter, which makes controlling Matomys populations particularly challenging.

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