includes excessive bleeding at venipuncture sites, the nose, and gums. Tissue is easily bruised. In some patients, after a few days of fever, their condition deteriorates into sudden shock (known as the dengue shock syndrome) with blotchy cool skin, cyanosis around the mouth, rapid pulse, and abnormally low blood pressure. In untreated cases of the dengue shock syndrome, the fatality may be as high as 40 to 50 percent.
Outbreaks of dengue hemorrhagic fever have been reported throughout Southeast Asia and Cuba. The occurrence is during the wet season when the Aedes aegypti population is highest. About a third of all deaths are under 15 years of age. This disease primarily affects the indigenous population.
The infectious agent is the dengue virus (types 1, 2, 3, and 4). The reservoir is Aedes aegypti mosquito and man, and it is transmitted by a mosquito bite. The disease is believed to occur by an immunological reaction from a second or subsequent infection with the dengue virus. See the Dengue Fever section for method of control.
Giardiasis
Giardiasis is a parasitic infection of the small intestine. Symptoms may include chronic diarrhea, excess fat in the stools, abdominal cramps, bloating, frequent loose pale stools, fatigue, and weight loss. The diagnosis is established by identification of cysts or trophozoites in feces.
Giardiasis occurs worldwide and in children more often than in adults. More cases occur in areas with poor sanitation, in institutions, and in day-care centers. Waterborne outbreaks have been frequently seen in the United States.
The infectious agent is Giardia lamblia, a protozoa. Reservoirs include man, beavers, and other wild or domestic animals.
Local outbreaks occur when the cysts are ingested with contaminated water and less often in fecally contaminated food. Transmission may occur from person to person by the fecal-oral route in day-care centers.
The incubation period ranges from 5 to 25 days. Giardiasis is communicable during the period of infection; undiagnosed carrier states are common. Treat the infection as directed by a medical officer. Quinicrine hydrochloride (Atabrine) or metronidazole (Flagyl) are drugs of choice.
Preventive measures for control include (1) filtering of public water supplies suspected to be at risk from human or animal fecal contamination; (2) ensuring that families, inmates, and personnel concerned with institutions and day-care centers receive training in personal hygiene after defecation; and (3) ensuring that emergency water supplies taken from suspected sources are boiled or treated with chlorine or iodine.
Management of patients, contacts, and the nearby environment include (1) enteric precautions for patients and (2) investigating contacts and the environment for the source of infections. There is no requirement for quarantine.
Epidemic measures include investigating cases to determine a common source, such as water, food, or direct contact, and instituting measures to prevent transmission.
Viral Hepatitis
Several different illnesses are considered as viral hepatitis; they have similarities and differences. This section will discuss the two major types.
VIRAL HEPATITIS A.— The onset is gradual over several days with symptoms of fever, malaise, loss of appetite, nausea, abdominal discomfort, and, a few days later, jaundice. The course of this disease varies from the commonly seen mild form (lasting for 1 to 2 weeks) to the uncommonly seen severe form (lasting several months). A convalescence of several weeks can be expected. Complete recovery without sequelae can be expected. Many cases are mildly symptomatic with no jaundice. Viral hepatitis A occurs worldwide in epidemics and is endemic in many developing countries. Many outbreaks occur in institutions, housing areas, and in military forces, This disease is more common in schoolage children and young adults.
The infectious agent is the hepatitis A virus. The reservoir is man. The average incubation period is about 28 to 30 days, but it will range from 15 to 50 days, depending on the virus dosage received.
Transmission is from person to person by the fecal-oral route. Hepatitis A virus is at the highest levels in feces 1 to 2 weeks before the symptoms occur and decreases rapidly after the onset of jaundice. Many outbreaks are spread by food and water. Raw or under-cooked clams and oysters have been incriminated. Viral hepatitis A appears to be most communicable during the 2 weeks before the symptoms occur and is probably not transmitted after the first week of illness. There is no specific treatment, except for supportive measures.