polluted water), and eating food prepared/served with  unwashed  hands.  The  average  incubation period is 2 to 3 days. It is communicable during the  period  when  the  stool  is  positive  for  Vibrio cholerae;  this period continues for a few days after recovery. Patients who develop into carriers may be  communicable  for  several  months. The primary treatment is with the administra- tion   of   large   amounts   of   oral   or   intravenous fluids.  Antibiotics  given  at  the  direction  of  a medical  officer  may  be  helpful  in  reducing  the duration and severity of diarrhea and fluid loss. Preventive  measures  for  control  of  the  disease include  (1)  proper  disposal  of  human  feces;  (2) providing clean drinking water and water treat- ment and disinfection; and (3) emphasizing good personal hygiene, especially handwashing before eating and after using the latrine. Management  of  patients,  contacts,  and  the nearby environment requires (1) isolation of pa- tients  by  enteric  (gastrointestinal)  precautions, e.g.,  handwashing  and  disposal  of  intestinal  ex- cretions;  (2)  observing  contacts  of  patients  for symptoms  5  days  from  the  last  exposure  (an- tibiotic  prophylaxis  and  immunization  are  not routinely  recommended);  and  (3)  conducting  an investigation  for  the  source  of  the  infection.  There is  no  requirement  for  quarantine. Epidemic  control  entails  (1)  providing  clean potable   water   and   sanitary   sewage   disposal; (2)  identifying  the  location  of  the  source  of  in- fection   and   appropriate   control   methods;   and (3)  ensuring  sanitary  food  handling. There  are  some  international  requirements. Ships  and  aircraft  arriving  from  cholera  areas must follow procedures outlined in International Health   Regulations; details  are  found  in SECNAVINST 6210.2. Except for a few specified countries, immunization is not required for inter- national  travel. Dengue Fever (Breakbone fever) Dengue  fever  is  characterized  by  a  sudden onset  of  fever  (occasionally  lasting  7  days  or more),  intense  headache,  pain  behind  the  eyes, joint and muscle pain, and a rash. There is early redness of the skin in some patients; usually for 3  to  4  days  after  the  beginning  of  fever,  a  rash presents  with  small  discolored  raised  spots  or closely   aggregated   bright   red   points.   Minute hemorrhagic or purpuric spots may appear on the feet, legs, axillae, or palate at about the same time the temperature returns to normal. Patients with dark  skin  often  have  no  visible  rash. The infectious agents are the viruses of dengue fever  (types  1,  2,  3,  and  4).  These  viruses  also cause  dengue  hemorrhagic  fever  (discussed  later). The reservoir is either man-mosquito or monkey- mosquito,   depending   on   the   geographic   area. Dengue is endemic to tropical Asia, West Africa, parts of the Caribbean, and several countries in Central  and  South  America. The virus is transmitted to man by the bite of mosquitoes  belonging  to  the  genus  Aedes.  Mos- quitoes  acquire  the  virus  by  biting  man  and,  in some  areas,  monkeys.  The  incubation  period  is usually 5 to 6 days. Patients are normally infec- tive to mosquitoes 24 hours before the onset until the fifth day of the disease. Treatment is suppor- tive;  there  are  no  specific  antibiotics. Preventive  measures  require  (1)  implementing mosquito   surveys   in   affected   communities   to determine the density of vector mosquitoes, iden- tifying breeding places, and eliminating the vec- tors where practical; and (2) making information available  to  the  public  concerning  methods  for protection  from  the  vector  mosquito  bites  such as the use of repellents, screening, and bed nets. Management  of  patients,  contacts,  and  the nearby  environment  includes  (1)  precautions  with patient  blood  by  denying  mosquitoes  access  to  the patient for at least 5 days after attack by using screens,  an  approved  residual  insecticide,  or  by the use of bed nets; and (2) investigation of a case including the place of residence at the time of in- fection (3 to 15 days prior to the onset) and search for unreported or undiagnosed cases. There is no requirement  for  quarantine  or  immunization. Epidemic measures, when necessary, include (1)   surveying,   locating,   and   eliminating   all manmade  Aedes  mosquito  breeding  places;  (2)  en- couraging   all   persons   who   are   occupationally exposed  to  the  vectors  to  use  repellents;  and (3) air dispersal of approved insecticides to stop epidemics. International measures require strict enforce- ment  of  all  existing  international  agreements designated to prevent the spread of this disease by  man,  monkey,  and  mosquitoes  via  ships, airplanes, and land transportation from endemic areas. Dengue Hemorrhagic Fever This severe illness affects primarily children, but  cases  can  be  seen  in  adults.  Symptoms  and signs  include  circulatory  shock,  high  fever,  loss of  appetite,  vomiting,  headache,  and  abdominal pain. A hemorrhagic phenomenon is seen, which 11-10