Osteoporosis: A Woman’s Disease Only? We are fearfully and wonderfully made.
By Peter N. Landless and Allan R. Handysides
I travel a lot, and I heard of an outbreak of yellow fever in Uganda. What is this disease, and should I be worried?
Yellow fever is a disease caused by a virus found in the tropical areas of Africa and South America. The virus is one of the flavivirus group; other flaviviruses include dengue, West Nile virus, and Zika. The disease takes its name from the jaundice it causes in some patients; accumulation of bilirubin as a result of liver damage results in a yellow discoloration of the sclera (white portions) of the eyes, mucous membranes of the mouth, and also the skin. It’s further classified as an acute viral hemorrhagic disease; other such diseases include Ebola, Marburg, and Lassa fever.
The virus is transmitted by the bite of infected mosquitoes, usually of the Aedes or Haemogogus species. It’s possible for mosquitoes to transmit the virus from people with yellow fever for a short while prior to the onset of fever and for approximately five days thereafter.
Once the disease is contracted, the virus incubates in the body for three to six days. The disease then follows one of two courses:
An acute phase with fever; muscle pains, including backache; headache; episodes of shivering (rigors); nausea; and possibly vomiting and loss of appetite. Most patients improve and symptoms clear within three to four days. Fifteen percent of patients have a more severe course, entering a more serious phase after the first four days. The fever returns, and the patient rapidly develops jaundice, with abdominal pain and vomiting. Bleeding may occur. The kidneys are affected and function deteriorates. Fifty percent of patients who enter this “toxic phase” die within 10 to 14 days; the remainder usually recover fully.
Yellow fever can be difficult to diagnose, as it may mimic malaria, dengue, or other hemorrhagic fevers. The diagnosis can be confirmed by blood tests, which detect the yellow fever antibodies produced in response to the viral infection. Additional sophisticated tests can help to detect the presence of the virus during the illness and even after death, when the cause of death is uncertain.
The World Health Organization (WHO) estimates that 44 nations—in Africa (31) and Latin America (13)— are at risk. The total population living in these countries is more than 900 million. WHO further estimates that since the early 1990s, 200,000 cases of yellow fever have been responsible for 30,000 deaths globally each year. Most of these cases have been in Africa. Additionally, a small number of cases are imported into countries traditionally free of yellow fever because of the movement of workers and travel in general. All these statistics would be much greater were it not for vaccination.
The single most important prevention measure against yellow fever is vaccination. It is safe and provides effective immunity against the disease within 10 days for 99 percent of those vaccinated. Serious side effects are extremely rare, making the risk/benefit ratio favorable, considering the significant mortality associated with yellow fever. Those who should not be vaccinated include infants younger than 9 months, pregnant women (except in an outbreak when the risk is very high), people with severe allergies to egg protein, and those with severe immune-compromised states, as in symptomatic HIV/AIDS. The risk/benefit needs to be carefully assessed in individuals over the age of 60, when adverse side effects are more common. Mosquito control is important at all times, but especially as populations are building immunity through vaccination programs.
Should you be worried? Enough to be vaccinated, and to encourage those who may be at risk to do likewise. Prevention is better than cure!
Peter N. Landless, a board-certified nuclear cardiologist, is director of the General Conference Health Ministries Department.
Allan R. Handysides, a board-certified gynecologist, is a former director of the General Conference Health Ministries Department.