Other Infectious Diseases
The international traveler may be potentially exposed to infectious
diseases for which no vaccines or preventive medications are currently
available. The following includes a brief description of selected
infectious diseases and appropriate precautions that may be of interest
to international travelers.
African sleeping sickness | Amebiasis
| American trypanosomiasis | Dengue
fever | Lassa fever | Leishmaniasis
| Onchocerciasis | Rift
Valley fever | Schistosomiasis
| Sexually transmitted diseases | Tickborne
African sleeping sickness (African
trypanosomiasis) is transmitted by the bite of the tsetse fly, a
large gray-brown insect approximately the size of a honeybee, which
bites during the day. Fever, rash or skin lesions, lethargy, and
confusion are usually the predominate signs and symptoms. Travelers
at risk should take personal protective measures
against these flies.
Amebiasis is caused by a protozoan
parasite. Infection is acquired by the fecal-oral route, either
by person-to-person contact or indirectly by eating or drinking
fecally contaminated food or water. Most infected persons do not
have symptoms. In persons with symptoms, diarrhea is most common.
Travelers at risk are advised to take appropriate food
and beverage precautions.
American trypanosomiasis (Chagas'
disease) is caused by a protozoan parasite that is usually transmitted
by contact with the feces of an infected reduviid bug. Transmission
may also occur through blood transfusion or via transplacental infection.
Acute infection may be asymptomatic or accompanied by a fever with
inflammation of the heart muscle or the lining of the brain or spinal
cord. Travelers at risk should take personal
protective measures against these bugs.
Dengue fever and dengue hemorrhagic
fever are viral diseases transmitted by urban Aedes mosquitos
that feed on humans during the daytime. Many cases of subclinical
or nonspecific infection occur, but dengue may also present as a
severe and fatal hemorrhagic disease. Dengue fever is characterized
by sudden onset, high fever, severe frontal headache, and joint
and muscle pain. Many patients have nausea, vomiting, and rash.
Travelers at risk should take personal protective
measures against these mosquitos.
Lassa fever is a severe, often fatal,
hemorrhagic fever that occurs in rural areas of West Africa, and
is caused by a virus transmitted from infected rodents to man. The
risk of infection in international travelers is considered small.
Leishmaniasis is a parasitic
disease acquired through the bite of some species of sand flies.
The disease most commonly manifests either in a cutaneous (skin)
form or in a visceral (internal organ) form. The appearance of disease
in the cutaneous form may take weeks to months after infection,
while the visceral form may take months to years to develop. Preventive
measures include reducing contact with sand flies and taking personal
protective measures against them.
Onchocerciasis (river blindness)
is transmitted by the bite of female Simulium flies (black
flies) that bite during the day and are found near rapidly flowing
rivers and streams. The disease may result in skin lesions, swollen
glands, and visual impairment, including blindness. Infections tend
to occur in expatriate groups such as missionaries and their families,
field scientists, and Peace Corps volunteers. Preventive measures
include avoidance of black fly habitats and use of personal
protective measures against them.
Rift Valley fever is a viral disease
transmitted by the bites of mosquitos and other biting insects,
and by skin inoculation or inhalation of aerosols from contaminated
blood or fluids of infected animals. Disease manifestations may
include fever with headache, fatigue, and muscle or joint pain.
More severe infections may also result in encephalitis, hemorrhage,
or blindness. Travelers visiting risk areas can reduce their exposure
by avoiding contact with livestock and taking personal
protective measures against mosquitos and other biting insects.
(bilharziasis) is caused by flukes whose complex life cycles utilize
specific fresh water snail species as intermediate hosts. Schistosomiasis
infection is estimated to occur among 200 million persons worldwide.
The most common acute symptoms include fever, weakness, headache,
and it may affect the gastrointestinal system. Chronic infections
can cause disease of the lungs, liver, intestines, or bladder. Even
brief exposures to contaminated water can result in infection. Those
at greatest risk are travelers who engage in wading or swimming
in fresh water in rural areas where poor sanitation and appropriate
snail hosts are present. Bathing with contaminated fresh water can
also transmit infection. Schistosomiasis is not acquired by wading
or swimming in salt water (oceans or seas). Travelers to risk areas
should take swimming precautions and
treat bath water by heating it to 122 degrees F for five minutes
or by treating it with iodine or chlorine (see food
and beverage precautions) to make it safe. In case of accidental
water exposure, vigorous towel drying is suggested as a possible
mechanism to interrupt skin penetration and infection.
Sexually transmitted diseases including
HIV infection and AIDS, are caused by numerous infectious agents.
Travelers should be aware that the risk of sexually transmitted
disease is very high in certain parts of the world. If treatment
does exist, it may be complicated by the emergence of antibiotic-resistant
strains of disease. To avoid acquiring sexually transmitted diseases,
travelers should not have sexual contact with persons who may be
infected. Persons most likely to be infected include those with
numerous sex partners, such as prostitutes. Travelers choosing to
have sexual contact may reduce their risk of acquiring infection
by always using a latex condom during intercourse.
Tickborne encephalitis is a viral
infection of the central nervous system transmitted by bites of
certain vector ticks. Risk of acquiring the disease is greater from
April through August. Infections follow bites of infected ticks,
usually in travelers who visit forests, fields, or pastures. Infection
may also be acquired by consuming unpasteurized dairy products from
infected cows, goats, or sheep. Travelers to risk areas should take
personal preventive measures against
ticks and avoid consumption of unpasteurized dairy products.