CHAPTER VIII
Preventive Medicine
The Preventive Medicine Division, Office of the Surgeon, USARV, was organizedlate in 1965 to advise the command on the incidence, prevalence, andepidemiological aspects of diseases which were likely to occur among U.S. Armycombat soldiers and, therefore, to be hazardous to military operations inVietnam.
The 20th Preventive Medicine Unit (Field), formerly the 20th PreventiveMedicine Laboratory, was the first preventive medicine unit deployed to Vietnam.Originally this unit and later four preventive medicine detachments functionedindependently, but late in 1967, higher echelon technical support was requiredand the four detachments were assigned to the 20th Preventive Medicine Unitwhich then assumed responsibility for the countrywide U.S. Army preventivemedicine program. When the 172d Preventive Medicine Unit (Field) becameoperational on 29 July 1968, the responsibility for preventive medicine supportin Vietnam was divided between the two units. Both units were assigned to the44th Medical Brigade, and each was augmented by two detachments, one controlteam and one survey team. Thus, countrywide deployment followed, from Quang Triin the north to Can Tho in the south.
Communicable Diseases
Malaria
Steady progress in the reduction of malaria in Vietnam had been possiblethrough vigorous command emphasis, improved preventive regimens, and increasedcontrol measures. A major change in the chloroquine-primaquine chemoprophylaxisprogram was instituted with Change 1 to USARV Regulation 40-4. This changestipulated that units in high-risk areas were to take daily dapsone tablets inaddition to weekly chloroquine-primaquine tablets as chemoprophylaxis against Plasmodiumfalciparum, the malarial parasite responsible for nearly 98 percent ofinfections occurring among troops. The command surgeon notified field commandersto enforce this change when manpower losses due to infections with P.falciparum were greater than 20 cases per 1,000 per annum per major unit.
The Wilson-Edeson test, adopted by the 172d Preventive Medicine Unit, tomeassure the amount of chloroquinc in urine, was rapid and
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convenient for field use. This test helped field commanders evaluateobjectively each unit's malaria chemoprophylaxis program and resulted in adramatic drop in the malaria rate in the units tested. Since slightly more than80 percent of all cases of malaria occurred in combat units, it was theresponsibility of field commanders to provide consistent and continuous commandemphasis on preventive measures. In addition to chloroquine-primaquine anddapsone chemoprophylaxis, personal protective measures to control malaria werestressed. Skin repellents, aerosol insecticide dispensers, bednets, and headnetswere in general use by field units. Combat units in remote forward areasreceived repellents and aerosol dispensers routinely.
For personnel departing Vietnam, commanders were urged to insure that themalaria chemoprophylaxis records of all returnees were reviewed as soon aspossible after arrival at their new duty station to make certain that eachreturnee had signed a "malaria debriefing" statement. This procedurewas recommended to prevent manpower loss and to limit the spread of malaria frominfected soldiers to susceptible persons in the United States and other areas.Those individuals who had not completed the 8-week chloroquine-primaquine courseand the 28-day dapsone course were to be given sufficient tablets to completethe malaria chemoprophylaxis course they were on in Vietnam.
Infectious Hepatitis
Beginning in 1966, all troops in Vietnam were inoculated with gamma globulinduring their first and fifth months of assignment to control infectioushepatitis. Later, as the troop strength increased, a system of selectivepriorities was set up for the use of this serum, based upon the premise of thegreatest need. Most cases of infectious hepatitis were caused by eating ordrinking contaminated food or water. The disease was of special concern whenthose infected were cooks or food handlers. Continuous efforts were made toinform all troops of the dangers inherent in consuming food purchased on theeconomy, where contact with the virus was unavoidable.
Diarrheal Diseases
The most common disease among U.S. soldiers in Vietnam was diarrhea. The ratefor this disease showed seasonal variations with peaks each year during May andJune, but the greater numbers of cases were sporadic and were usually caused bya breakdown in unit mess sanitation or by eating procured vegetablescontaminated with Shigella and Salmonella. No specific etiologicalagent was identified for most of the diarrheal cases admitted for treatment.Shigellosis accounted for most cases for which an agent could be identified.
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Measures were continued to improve mess and water sanitation and wastedisposal practices, and to educate the soldiers in basic field and foodsanitation. The use of disposable paper plates and plastic eating utensilseradicated a potential source of diarrheal disease-inadequately cleaned messgear.
Skin Disease
Skin disease caused by prolonged exposure to wetness followed by secondaryinvasion of the injured tissue by fungal or bacterial agents was a problem amongU.S. Army ground troops fighting in inundated areas during the monsoon season.The Office of the Surgeon, USARV, recommended that all combat units be providedwith zipper boots, inserts, and nylon socks. The most useful preventive measureswere limiting participation in combat operations in wet areas to 48 hours,intensive foot care during the "drying out" period which followed,frequent changes of boots and socks, and prophylactic use of griseofulvin.
Fever of Undetermined Origin
Fever of undetermined origin was a major cause of morbidity in Vietnam.Elaborate studies were initiated before 1966 in an attempt to identify theetiological agent or agents involved. By 1968, through laboratory efforts, 40percent of the admissions were identified as caused by arboviruses or otherarthropodborne agents. The preventive measures used were insect sprays andbednets.
Rabies
As the U.S. Army troop buildup in Vietnam increased, there was a concomitantrise in the number of animal bite cases treated in USARV medical facilities. Themajor difficulties were the sheer number of pets acquired by Americans, thelarge number of small units and detachments scattered among the Vietnamesecommunities, and the lack of a meaningful civilian rabies control program. Therewere no cases of rabies among USARV personnel during 1965-70, although severalthousand soldiers received the antirabies vaccine prophylaxis when the bitinganimal was not apprehended.
To control rabies in pets, the preventive medicine rabies control programrequired that each unit commander determine the number of animals to be allowedin his area, that all animals be registered, and that each animal be vaccinatedagainst rabies and restrained within the unit area. Little restraint of pets wasever noted in Vietnam.
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Other Communicable Diseases
Other communicable diseases of special concern occurred in Vietnam andcould have become a threat with the increase of troop strength and accelerationof combat operations without an effective preventive medicine program.
The admission rates for common respiratory disease and influenza remainedrelatively moderate from 1965 to 1970. Although an outbreak of influenza in HongKong in July 1968 was caused by a strain of influenza virus sufficientlydifferent to warrant concern ever a probable pandemic, only a few cases appearedin military units in Vietnam. The monovalent vaccine became available in limitedamounts in January and February 1969.
Melioidosis, a glanders-like disease observed in rodents and occasionally inman, was rarely encountered by the Army before deployment of troops to Vietnam. Pseudomonaspseudomallei, the causative agent of melioidosis, was cultured from samplesof oil, market fruits and vegetables, well water, and surface water. These mayhave been the source of infection since man-to-man transmission was notobserved. Recognition and early treatment were the prime factors in reducing themelioidosis mortality rate in 1968.
Dengue fever was reported in small numbers during 1966, and scrub typhuscases in even fewer numbers. Immunization against typhus, routine since late1962, was temporarily discontinued on 25 February 1969, because availablevaccines were not potent enough to protect individuals against louseborne typhusfever.
Although both cholera and plague were prevalent during 1966 among the civilpopulation of Vietnam, no cases of cholera occurred among U.S. troops from 1965to 1970. As of 19 April 1968, five confirmed cases of plague and one unconfirmedcase had occurred among U.S. Army personnel.
Environmental Sanitation
Field Sanitation Training
Instructors in preventive medicine units and detachments continuouslystressed basic hygiene and sanitation, malaria chemoprophylaxis, insect and postcontrol, waste disposal, and unit and individual protective measures againstarthropodborne and waterborne diseases as well as other health hazards thatcaused discomfort to troops or damage to materiel.
Water Supply Surveillance
Major emphasis was placed on medical surveillance of field water points andcantonment water supply systems. Preventive medicine units providedfirst-echelon surveillance of water supplies for organizations
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Preventive Medicine Unit Team Member Using the MiteyMite Backpack Sprayer-Duster
without assigned medical personnel, and second-echelon surveillance of watersupplies for all others. The USARV requirement for free available chlorine inwater was strictly enforced: 5.0 parts per million after 30 minutes contact atfield water points and 2.0 parts per million at field consumption points.
Preventive medicine units also provided medical surveillance of iceplants,including residual chlorine and bacteriological testing of the quality of water.Ice consumed or used for chilling foods and beverages was supplied by iceplantsoperated by the Army or by Army-approved local civilian firms.
Waste Disposal Practice
Monitoring waste disposal practices was another important preventive medicineactivity; no major breakdowns in the waste disposal systems were related todisease outbreaks. In general, field units used urine soakage pits, with orwithout "urineoils," and "burn-out" latrines for thedisposal of human excreta. For liquid wastes, oxidation ponds and sewagelagoons were used as well as septic tanks with soil absorption beds. Refuse-garbage, trash, kitchenwastes-was disposed of in sanitary fills. Infectiouswastes from hospitals and other medical facilities were disposed of inhigh-temperature incinerators or by special packaging and burial.
Food Service Sanitation
Messkit sanitation procedures were almost totally unnecessary in Vietnam.Troops provided with rations used plastic trays, paper plates, or, in rarecases, chinaware. The individual combat meal (C-ration) was usually eaten withthe utensils provided with the ration. The use of food service disinfectants, anitem of special interest for USARV annual general inspections, was emphasized.
Pest Control Measures
Pest control in USARV was an integrated program involving the co-ordinatedefforts of unit field sanitation teams, contract engineer entomology services,and preventive medicine units and detachments. Unit self-help sparked by trainedfield sanitation teams was the backbone of the program. In addition to pestcontrol, preventive medicine person-
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nel provided first- and second-echelon support to unit programs and insuredthat field sanitation teams were trained. Contract engineer entomology serviceswere provided at major installations and base camps throughout Vietnam byPacific Architects and Engineers and by the Philco Ford Company. Preventivemedicine units conducted ground fogging and mist operations in remote areaswhere contract entomology services were lacking. Close liaison and co-operationwere encouraged by medical entomologists with engineer entomologists to insurerapid exchange of information. The engineer program was unique in that it wasthe first time in recent history that the mission of pest control had been givenon a broad scale to a civilian contractor in a combat zone.
Quarantine and Inspection Procedures
Early in the 1960's, the Armed Forces Pest Control Board was designated theco-ordinating agency for development of appropriate insect and rodent controlprograms for the Armed Forces. The Armed Forces had become increasingly aware ofthe real threat of accidental importation into the United States from Vietnam ofpests and diseases of agricultural and medical concern. The inherent problems ofinspecting vast quantities of cargo at U.S. ports of entry demanded theestablishment of a preshipment quarantine inspection program for military cargo.Quarantine inspection of vessels, aircraft, and retrograde cargo in Vietnam waspart of a co-operative preventive medicine program between the Department ofDefense, the USPHS (U.S. Public Health Service), and the USDA (U.S. Departmentof Agriculture) during 1969. More than 350 medical personnel of the Army, Navy,and Air Force were trained and certified as USPHS and USDA quarantineinspectors. A 24-hour daily inspection service was maintained at major maritimeand aerial ports operated by the Armed Forces for incoming and outgoing cargo.In addition, by special arrangement, cargo shipments were inspected andcertified at auxiliary ports located throughout Vietnam.
Professional Conferences
Three USARV preventive medicine conferences were held during a 12-monthperiod in 1968 and 1969. These 1-day conferences were conducted as workingseminars and included formal presentations and informal study groups. About 75individuals attended each conference. Besides participants from all USARVcommands, there were preventive medicine representatives of the Surgeon, USMACV;AID; and ARVN. The seminars and panel discussions covered all phases ofpreventive medicine and provided the means for exchange of information and theopportunity to profit from the experience of personnel in different areas ofVietnam.
