Thorough searching includes the examination of animal nests (especially wood rat) for the presence of bones, clothing, or shiny personal items possibly from a presumed dead subject. I have received inquiries about the hazards of contracting Hantavirus from dismantling rodent nests. In this regard, I have summarized an article in the November 1996 edition of the Journal of Forensic Sciences on the subject.
Fink, T. Michael: "Rodents, Human Remains, and North American Hantaviruses: Risk Factors and Prevention Measures for Forensic Science Personnel." JFS, Vol. 41, #6, November 1996. pp. 1052-1056.
Hantavirus was identified in 1993 as the cause of a severe form of respiratory distress, later termed Hantavirus pulmonary syndrome (HPS). Hantavirus is typically found in a rodent population, and is shed in their saliva, urine, and feces. Humans become infected after inhaling aerosolized droplets of urine or particulates contaminated with rodent excreta. There have been 128 cases of HPS reported in the US (1993-2/96) with a mortality of approximately 50%. There is probably a greater incidence among agricultural workers, with mortality/morbidity being attributed to other disease conditions. A large proportion of the cases occurred among forensic science and anthropological workers. The primary vector is the deer mouse, however the common wood rat is identified as a co-vector. It has been observed that there is a coincidence of Hantavirus within rodent populations harboring plague, therefore personnel should consider protecting themselves against both virus and flea-borne disease with conducting activities that might lead to exposure.
(Risk factors we might identify in search activities are dismantling of wood rat nests, and movement of remains that have been subject to rodent activity.)
Appropriate measures include protection against inhalation of contaminated particulates, protection against particulates coming into contact with conjunctiva (eyes), and protection against fleabites. In certain circumstances, decontamination measures might be taken before moving debris or dismantling nests.
The recommendation for respiratory protection is a HEPA respirator (i.e., something that covers the mouth and nose, uses a particulate filter, and is not just a bandana or surgical mask.) Goggles are appropriate eyewear. Surgical gloves taped or pulled over long sleeves are appropriate to protect against fleabites, as is taping of pants at ankles.
Lysol spray left on for 10 minutes will decontaminate most surfaces, however should be avoided if there is any possibility the evidence may be osteological specimens that will undergo carbon-14 dating. This would commonly be the case when excavating or recovering possible Native American sites. In general search situations, this may not be as significant an issue.
Therefore, I propose the following protocols for discussion:
1. Personnel actively involved in dismantling a rodent nest or moving remains that have been disturbed by rodents should be wearing a HEPA respirator that covers the mouth and nose. Personnel should also wear latex or other barrier gloves, long sleeves, long pants, and closed pants legs.
2. Rodent nests that are to be dismantled should first be sprayed with common aerosol Lysol, with a 10 minute wait prior to dismantling. The exception to use of Lysol would be if there were a high expectation that osteological evidence will be found in the nest, and that the bone evidence would be subject to carbon dating.
3. Implements used to dismantle nests should be sprayed with Lysol aerosol after use.
4. In areas where plague is known, rodent nests should be sprayed with an insecticide specific for fleas prior to dismantling.
5. In a situation where rodent nests are found within corpses or osteological remains, the nests should be removed from the remains before spraying with insecticide and Lysol to prevent destruction of chemically sensitive evidence.
Clearly, most searchers are in greater danger while driving to and from a search scene that from Hantavirus or Plague, however the rapid mortality associated with these diseases and the rodent as a vector encourages us to take some form of minimum precautions.
Perhaps some of you have other information to share. I am particularly interested in developing decontamination protocols that provide sufficient protection to personnel yet do not chemically contaminate potential evidence.
Michael M.
Zanoni, Ph.D.
Independent Consultant
Zanoni@netcom.com