Surveillance for Enteric Parasites among U.S. Military Personnel and Civilian Staff on Joint Task Force Base-Bravo in Soto Cano, Honduras and the Local Population in Comayagua and La Paz, Honduras

Military Medicine, Nov 2004 by Kwa, Boo H, Aviles, Ricardo, Tucker, Matthew S, Sanchez, Jaime A, Et al

A study was conducted in Honduras to address whether military personnel assigned to Joint Task Force-Bravo in Soto Cano, Honduras, routinely acquire parasite infections, and the results were compared with those collected from civilian base workers and the general local population in the nearby towns of Comayagua and La Paz. Results from this study report 21 species of enteric parasites among Hondurans living in Comayagua and La Paz, 13 species among local Hondurans working as base civilian personnel, and 3 species among U.S. military servicemen and women. The most prevalent organism found was Blastocystis hominis, infecting 95 people (35.8% of 265 samples). Prevalence rates in this study are similar to documented reports on parasite transmission in Central American countries and other areas of Honduras. Although preventive protocols for U.S. military "force protection" appear to be effective in controlling transmission, continuous surveillance for enteric parasites is warranted because of the high parasite loads in the populations with which military personnel come into contact.

Introduction

United States military personnel serving overseas in different geographical regions may become infected with parasites prevalent in those locales. They may potentially act as silent carriers and contribute to transnational transmission because U.S. troops undergo continuous reassignments to different theaters. Furthermore, intense transmission of enteric parasites is likely to be exacerbated in situations of wartime disruption. In the wake of a major disaster or conflict, extreme conditions are likely to contribute to contamination of the environment with parasites where both military and civilian personnel are expected to operate. Other adverse conditions may increase vector habitats and possibly increase infections not only in the indigenous population, but also in civilian and military relief workers. Natural disasters (e.g., hurricanes and floods) not only disrupt the normal life of the local inhabitants but also overwhelm an already inadequate sanitation infrastructure. These calamities particularly affect regions of the Caribbean, including Central and South America, where much of recent U.S. Southern Command (SOUTHCOM) military and civilian humanitarian efforts have been focused. The disasters have included earthquakes in Colombia, Peru, and hurricanes affecting the islands of the Caribbean and countries of Central America (e.g., Honduras affected by Hurricane Mitch). When relief workers perform their duties in these unsanitary conditions, there is a greater risk of contracting communicable diseases. Many soilborne infections (e.g., hookworms) may pose risks to populations through direct environmental exposure. Moreover, relief personnel may be exposed to food-borne and water-borne infections when eating unfamiliar local foods or drinking unsafe water. The less evident parasitic diseases such as those caused by enteric helminths and protozoa have been largely neglected in most recent research literature, and this has led to an underestimation of the serious health effects these diseases can cause.

In August 2001, we visited Joint Task Force-Bravo in Soto Cano, Honduras, with the purpose of establishing contact with key military personnel. Through discussions of project aims and goals, we determined logistics for collection of fecal samples and diagnosis of enteric infections. The air base of Soto Cano in Honduras was selected for its unique role in providing humanitarian assistance to the Honduran population. In addition, Soto Cano Air Base is located in the valley of Comayagua, with its tropical climate ideal for all forms of helminth and protozoa to survive and maintain their presence among the inhabitants of the region. U.S. military personnel work in conjunction with the Honduran military and civilian organizations by providing medical assistance to underprivileged people with no access to health care. There is also cooperation in the area of civil engineering. After Hurricane Mitch, most of the country suffered devastation of its already fragile infrastructure, thus requiring assistance to rebuild roads, bridges, and schools. Armed Forces maintain missions dedicated to provide such post- disaster relief missions, thus mobilizing personnel to work in areas where sanitary conditions are very poor.

This study was conducted jointly by SOUTHCOM/Joint Task Force-Bravo (JTFB) and the University of South Florida College of Public Health. The purpose of the study was to assess the infection risk of military personnel exposed to intestinal parasites when on field assignments (such as humanitarian assistance missions). In Soto Cano, support was given by the Medical Element (MEDEL) to provide the logistics and cooperation in the study. Operations run by MEDEL comprise all basic medical services to military personnel stationed at the base, as well as to provide support and organize health campaigns in remote underserved areas of Honduras. The plan for sample collection included obtaining stool samples from military units deployed monthly from the United States to provide relief (either medical units or engineer units) to measure their risk of infection with intestinal parasites. We theorized that military personnel might acquire parasites when dining and working outside of the base. Stool samples were also collected from the local population to obtain a cross-sectional profile of the local distribution of intestinal parasite infections. This would give us an idea of the types of parasites that the military might be exposed to outside of the base. A third group consisting of Hondurans working on base was later added to determine the prevalence of infections in support workers and to determine whether this group might represent a risk of disease transmission to military personnel.