The major health risks in Botswana are Malaria, Typhoid and HIV/Aids. A
Polio vaccine is recommended for any adult traveller who completed the
childhood series, but never had a vaccine as an adult. Malaria is a
particular risk between November and June in the northern parts of the
country. There are no compulsory vaccinations, but a yellow fever
vaccination certificate is required from travellers over one year of
age coming from infected countries. Occasional outbreaks of anthrax
occur among wild animals, and visitors to affected national parks
should seek local advice. Botswana has a good public health system, but
facilities are limited outside urban areas. Health insurance for
visitors is vital. Tap water in towns is safe to drink, and all
foodstuffs are safe to consume.
Cause: Salmonella typhi, the typhoid bacillus, which infects only humans. Similar paratyphoid and enteric fevers are caused by other species of Salmonella, which infect domestic animals as well as humans. Transmission:
Infection with typhoid fever is transmitted by consumption of
contaminated food or water. Occasionally direct faecal-oral
transmission may occur. Shellfish taken from sewage-polluted beds are
an important source of infection. Infection occurs through eating fruit
and vegetables fertilized by night soil and eaten raw, and milk and
milk products that have been contaminated by those in contact with
them. Flies may transfer infection to foods, resulting in contamination
that may be sufficient to cause human infection. Pollution of water
sources may produce epidemics of typhoid fever, when large numbers of
people use the same source of drinking water. Nature of the disease:
Typhoid fever is a systemic disease of varying severity. Severe cases
are characterized by gradual onset of fever, headache, malaise,
anorexia and insomnia. Constipation is more common than diarrhoea in
adults and older children. Without treatment, the disease progresses
with sustained fever, bradycardia, hepatosplenomegaly, abdominal
symptoms and, in some cases, pneumonia. In white-skinned patients, pink
spots (papules), which fade on pressure, appear on the skin of the
trunk in up to 50% of cases. In the third week, untreated cases develop
additional gastrointestinal and other complications, which may prove
fatal. Around 2-5% of those who contract typhoid fever become chronic
carriers, as bacteria persist in the biliary tract after symptoms have
resolved. Geographical distribution: Worldwide. The disease
occurs most commonly in association with poor standards of hygiene in
food preparation and handling and where sanitary disposal of sewage is
lacking. Risk for travellers: Generally low risk for
travellers, except in parts of north and west Africa, in south Asia and
in Peru. Elsewhere, travellers are usually at risk only when exposed to
low standards of hygiene with respect to food handling, control of
drinking water quality, and sewage disposal. Prophylaxis (protective treatment): Vaccination. Precautions: Observe all precautions against exposure to foodborne and waterborne infections. Source: WHO.
Rabies
Cause: The rabies virus, a rhabdovirus of the genus Lyssavirus. Transmission:
Rabies is a zoonotic disease affecting a wide range of domestic and
wild animals, including bats. Infection of humans usually occurs
through the bite of an infected animal. The virus is present in the
saliva. Any other contact involving penetration of the skin occurring
in an area where rabies is present should be treated with caution. In
developing countries transmission is usually from dogs.
Person-to-person transmission has not been documented. Nature of the disease:
An acute viral encephalomyelitis, which is almost invariably fatal. The
initial signs include a sense of apprehension, headache, fever, malaise
and sensory changes around the site of the animal bite. Excitability,
hallucinations and aerophobia are common, followed in some cases by
fear of water (hydrophobia) due to spasms of the swallowing muscles,
progressing to delirium, convulsions and death a few days after onset.
A less common form, paralytic rabies, is characterized by loss of
sensation, weakness, pain and paralysis. Geographical distribution: Rabies is present in animals in many countries worldwide. Most cases of human infection occur in developing countries. Risk for travellers:
In rabies-endemic areas, travellers may be at risk if there is contact
with both wild and domestic animals, including dogs and cats. Prophylaxis (protective treatment):
Vaccination for travellers with a foreseeable significant risk of
exposure to rabies or travelling to a hyperendemic area where modern
rabies vaccine may not be available. Precautions:
Avoid contact with wild animals and stray domestic animals,
particularly dogs and cats, in rabies-endemic areas. If bitten by an
animal that is potentially infected with rabies, or after other suspect
contact, immediately clean the wound thoroughly with disinfectant or
with soap or detergent and water. Medical assistance should be sought
immediately. The vaccination status of the animal involved should not
be a criterion for withholding post-exposure treatment, unless the
vaccination has been thoroughly documented and vaccine of known potency
has been used. In the case of domestic animals, the suspect animal
should be kept under observation for a period of 10 days. Rabies post-exposure treatment:
In a rabies-endemic area, the circumstances of an animal bite, other
contact with the animal, and the animal's behaviour and appearance may
suggest that it is rabid. In such situations, medical advice should be
obtained immediately. Post-exposure treatment to prevent the
establishment of rabies infection involves first-aid treatment of the
wound followed by administration of rabies vaccine and antirabies
immunoglobulin in the case of a bite or exchange of saliva. The
administration of vaccine, and immunoglobulin if required, must be
carried out, or directly supervised, by a physician. Source: WHO.
Malaria
General considerations: Malaria is a common and
life-threatening disease in many tropical and subtropical areas. It is
currently endemic in over 100 countries, which are visited by more than
125 million international travellers every year. Each year many
international travellers fall ill with malaria while visiting countries
where the disease is endemic, and well over 10,000 fall ill after
returning home. Fever occurring in a traveller within three months of
leaving a malaria-endemic area is a medical emergency and should be
investigated urgently. Cause: Human malaria is caused by four different species of the protozoan parasite Plasmodium: Plasmodium falciparum, P. vivax, P. ovale and P. malariae. Transmission: The malaria parasite is transmitted by various species of Anopheles mosquitoes, which bite mainly between sunset and sunrise. Nature of the disease:
Malaria is an acute febrile illness with an incubation period of 7 days
or longer. Thus, a febrile illness developing less than one week after
the first possible exposure is not malaria. The most severe form is
caused by P. falciparum, in which variable clinical features
include fever, chills, headache, muscular aching and weakness,
vomiting, cough, diarrhoea and abdominal pain; other symptoms related
to organ failure may supervene, such as: acute renal failure,
generalized convulsions, circulatory collapse, followed by coma and
death. It is estimated that about 1% of patients with P. falciparum
infection die of the disease. The initial symptoms, which may be mild,
may not be easy to recognize as being due to malaria. It is important
that the possibility of falciparum malaria is considered in all cases
of unexplained fever starting at any time between the seventh day of
first possible exposure to malaria and three months (or, rarely, later)
after the last possible exposure, and any individual who experiences a
fever in this interval should immediately seek diagnosis and effective
treatment. Early diagnosis and appropriate treatment can be
life-saving. Falciparum malaria may be fatal if treatment is delayed
beyond 24 hours. A blood sample should be examined for malaria
parasites. If no parasites are found in the first blood film but
symptoms persist, a series of blood samples should be taken and
examined at 6-12-hour intervals. Pregnant women, young children and
elderly travellers are particularly at risk. Malaria in pregnant
travellers increases the risk of maternal death, miscarriage,
stillbirth and neonatal death. The forms of malaria caused by other Plasmodium
species are less severe and rarely life-threatening. Prevention and
treatment of falciparum malaria are becoming more difficult because P. falciparum
is increasingly resistant to various antimalarial drugs. Of the other
malaria species, drug resistance has to date been reported for P. vivax, mainly from Indonesia (Irian Jaya) and Papua New Guinea, with more sporadic cases reported from Guyana. P. vivax
with declining sensitivity has been reported for Brazil, Colombia,
Guatemala, India, Myanmar, the Republic of Korea, and Thailand. P. malariae resistant to chloroquine has been reported from Indonesia. Geographical distribution:
The risk for travellers of contracting malaria is highly variable from
country to country and even between areas in a country. In many endemic
countries of Latin America and the Caribbean, Asia and the
Mediterranean region, the main urban areas, but not necessarily the
outskirts of towns, are free of malaria transmission. However, malaria
can occur in main urban areas in Africa and India. There is usually
less risk of the disease at altitudes above 1,500 metres, but in
favourable climatic conditions it can occur at altitudes up to almost
3,000 metres. The risk of infection may also vary according to the
season, being highest at the end of the rainy season. There is no risk
of malaria in many tourist destinations in South-East Asia, Latin
America and the Caribbean. Source: WHO.
HIV/AIDS and Sexually Transmitted Diseases
The most important sexually transmitted diseases and infectious
agents are HIV/AIDS, hepatitis B, syphilis, gonorrhoea, chlamydia
infections, trichomoniasis, chancroid, genital herpes and genital
warts. Transmission: Infection occurs during unprotected sexual
intercourse. Hepatitis B, HIV and syphilis may also be transmitted in
contaminated blood and blood products, by contaminated syringes and
needles used for injection, and potentially by unsterilized instruments
used for acupuncture, piercing and tattooing. Nature of the diseases:
Most of the clinical manifestations are included in the following
syndromes: genital ulcer, pelvic inflammatory disease, urethral
discharge and vaginal discharge. However, many infections are
asymptomatic. Sexually transmitted infections are a major cause of
acute illness, infertility, long-term disability and death, with severe
medical and psychological consequences for millions of men, women and
children. Apart from being serious diseases in their own right,
sexually transmitted infections increase the risk of HIV infection. The
presence of an untreated disease (ulcerative or non-ulcerative) can
increase by a factor of up to 10 the risk of becoming infected with HIV
and transmitting the infection. On the other hand, early diagnosis and
improved management of other sexually transmitted infections can reduce
the incidence of HIV infection by up to 40%. Prevention and treatment
of all sexually transmitted infections are therefore important for the
prevention of HIV infection. Geographical distribution:
Worldwide. Sexually transmitted infections have been known since
ancient times; they remain a major public health problem, which was
compounded by the appearance of HIV/AIDS around 1980. An estimated 340
million episodes of curable sexually transmitted infections (chlamydial
infections, gonorrhoea, syphilis, trichomoniasis) occur throughout the
world every year. Viral infections, which are more difficult to treat,
are also very common in many populations. Genital herpes is becoming a
major cause of genital ulcer, and subtypes of the human papillomavirus
are associated with cervical cancer. Risk for travellers:
For some travellers there may be an increased risk of infection. Lack
of information about risk and preventive measures and the fact that
travel and tourism enhance the probability of having sex with casual
partners increase the risk of exposure to sexually transmitted
infections. In some developed countries, a large proportion of sexually
transmitted infections now occur as a result of unprotected sexual
intercourse during international travel. In addition to transmission
through sexual intercourse (both heterosexual and homosexual-anal,
vaginal or oral), most of these infections can be passed on from an
infected mother to her unborn or newborn baby. Hepatitis B, HIV and
syphilis are also transmitted through transfusion of contaminated blood
or blood products and the use of contaminated needles. There is no risk
of acquiring any sexually transmitted infection from casual day-to-day
contact at home, at work or socially. People run no risk of infection
when sharing any means of communal transport (e.g. aircraft, boat, bus,
car, train) with infected individuals. There is no evidence that HIV or
other sexually transmitted infections can be acquired from insect
bites. Prophylaxis: There is a vaccination against hepatitis B. No prophylaxis is available for any of the other sexually transmitted diseases. Precautions:
Male or female condoms, when properly used, have proved to be effective
in preventing the transmission of HIV and other sexually transmitted
infections, and for reducing the risk of unwanted pregnancy. Latex
rubber condoms are relatively inexpensive, are highly reliable and have
virtually no side-effects. The transmission of HIV and other infections
during sexual intercourse can be effectively prevented when
high-quality condoms are used correctly and consistently. Studies on
serodiscordant couples (only one of whom is HIV-positive) have shown
that, with regular sexual intercourse over a period of two years,
partners who consistently use condoms have a near-zero risk of HIV
infection. A man should always use a condom during sexual intercourse,
each time, from start to finish, and a woman should make sure that her
partner uses one. A woman can also protect herself from sexually
transmitted infections by using a female condom - essentially, a
vaginal pouch, which is now commercially available in some countries.
It is essential to avoid injecting drugs for non-medical purposes, and
particularly to avoid any type of needle-sharing to reduce the risk of
acquiring hepatitis, HIV, syphilis and other infections from
contaminated needles and blood. Medical injections using unsterilized
equipment are also a possible source of infection. If an injection is
essential, the traveller should try to ensure that the needles and
syringes come from a sterile package or have been sterilized properly
by steam or boiling water for 20 minutes. Patients under medical care
who require frequent injections, e.g. diabetics, should carry
sufficient sterile needles and syringes for the duration of their trip
and a doctor's authorization for their use. Unsterile dental and
surgical instruments, needles used in acupuncture and tattooing,
ear-piercing devices, and other skin-piercing instruments can likewise
transmit infection and should be avoided. Treatment:
Travellers with signs or symptoms of a sexually transmitted disease
should cease all sexual activity and seek medical care immediately. The
absence of symptoms does not guarantee absence of infection, and
travellers exposed to unprotected sex should be tested for infection on
returning home. HIV testing should always be voluntary and with
counselling. The sexually transmitted infections caused by bacteria,
e.g. chancroid, chlamydia, gonorrhoea and syphilis, can be treated
successfully, but there is no single antimicrobial that is effective
against more than one or two of them. Moreover, throughout the world,
many of these bacteria are showing increased resistance to penicillin
and other antimicrobials. Treatment for sexually transmitted viral
infections, e.g. hepatitis B, genital herpes and genital warts, is
unsatisfactory due to lack of specific medication, and cure is
difficult to achieve. The same is true of HIV infection, which in its
late stage causes AIDS and is thought to be invariably fatal.
Antiretroviral drugs cannot completely eradicate the HIV virus;
treatment is expensive and complex and most countries have only a few
centres that are able to provide it. Source: WHO.
Hepatitis B
Cause: Hepatitis B virus (HBV), belonging to the Hepadnaviridae. Transmission:
Hepatitis B is transmitted from person to person by contact with
infected body fluids. Sexual contact is an important mode of
transmission, but infection is also transmitted by transfusion of
contaminated blood or blood products, or by use of contaminated needles
or syringes for injections. There is also a potential risk of Hepatitis
B transmission through other skin-penetrating procedures including
acupuncture, piercing and tattooing. Perinatal transmission may occur
from mother to baby. There is no insect vector or animal reservoir. Nature of the disease:
Many HBV infections are asymptomatic (e.g. causes no symptoms) or cause
mild symptoms, which are often unrecognised in adults. When clinical
hepatitis results from infection, it has a gradual onset, with
anorexia, abdominal discomfort, nausea, vomiting, arthralgia and rash,
followed by the development of jaundice in some cases. In adults, about
1% of cases are fatal. Chronic HBV infection persists in a proportion
of adults, some of whom later develop cirrhosis and/or liver cancer. Geographical distribution:
Worldwide, but with differing levels of endemicity. In north America,
Australia, northern and western Europe and New Zealand, prevalence of
chronic HBV infection is relatively low (less than 2% of the general
population). Risk for travellers: Negligible for those
vaccinated against hepatitis B. Unvaccinated travellers are at risk if
they have unprotected sex or use contaminated needles or syringes for
injection, acupuncture, piercing or tattooing. An accident or medical
emergency requiring blood transfusion may result in infection if the
blood has not been screened for HBV. Travellers engaged in humanitarian
relief activities may be exposed to infected blood or other body fluids
in health care settings. Prophylaxis (protective treatment): Vaccination. Precautions:
Adopt safe sexual practices and avoid the use of any potentially
contaminated instruments for injection or other skin-piercing activity.
Source: WHO.
Hepatitis A
Cause: Hepatitis A virus, a member of the picornavirus family. Transmission:
The virus is acquired directly from infected persons by the faecal-oral
route or by close contact, or by consumption of contaminated food or
drinking water. There is no insect vector or animal reservoir (although
some non-human primates are sometimes infected). Nature of the disease:
An acute viral hepatitis with abrupt onset of fever, malaise, nausea
and abdominal discomfort, followed by the development of jaundice a few
days later. Infection in very young children is usually mild or
asymptomatic (e.g. causes no symptoms); older children are at risk of
symptomatic disease. The disease is more severe in adults, with illness
lasting several weeks and recovery taking several months; case-fatality
is greater than 2% for those over 40 years of age and 4% for those over
60. Geographical distribution: Worldwide, but most common where sanitary conditions are poor and the safety of drinking water is not well controlled. Risk for travellers:
Non-immune travellers to developing countries are at significant risk
of infection. The risk is particularly high for travellers exposed to
poor conditions of hygiene, sanitation and drinking water control. Prophylaxis (protective treatment): Vaccination. Precautions:
Travellers who are non-immune to hepatitis A (i.e. have never had the
disease and have not been vaccinated) should take particular care to
avoid potentially contaminated food and water. Source: WHO.
Anthrax
Cause: Bacillus anthracis bacteria. Transmission:
Cutaneous infection, the most frequent clinical form of anthrax, occurs
through contact with contaminated products from infected animals
(mainly cattle, goats, sheep), such as leather or woollen goods, or
through contact with soil containing anthrax spores. Nature of the disease:
Anthrax is a disease of herbivorous animals that occasionally causes
acute infection in humans, usually involving the skin, as a result of
contact with contaminated tissues or products from infected animals, or
with anthrax spores in soil. Untreated infections may spread to
regional lymph nodes and to the bloodstream, and may be fatal. Geographical distribution: Sporadic cases of Anthrax occur in animals worldwide; there are occasional outbreaks in central Asia. Risk for travellers: The risk of Anthrax is very low for most travellers. Prophylaxis (protective treatment): None. (A vaccine is available for people at high risk because of occupational exposure to Bacillus anthracis; it is not commercially available in most countries.) Precautions: Avoid direct contact with soil and with products of animal origin, such as souvenirs made from animal skins. Source: WHO.
Yellow fever
Cause: The yellow fever virus, an arbovirus of the
Flavivirus genus.
Transmission: Yellow fever in urban and some rural areas is transmitted by the bite of infective
Aedes aegypti
mosquitoes and by other mosquitoes in the forests of south America. The
mosquitoes bite during daylight hours. Transmission occurs at altitudes
up to 2,500 metres. Yellow fever virus infects humans and monkeys. In
jungle and forest areas, monkeys are the main reservoir of infection,
with transmission from monkey to monkey carried out by mosquitoes. The
infective mosquitoes may bite humans who enter the forest area, usually
causing sporadic cases or small outbreaks. In urban areas, monkeys are
not involved and infection is transmitted among humans by mosquitoes.
Introduction of infection into densely populated urban areas can lead
to large epidemics of yellow fever. In Africa, an intermediate pattern
of transmission is common in humid savannah regions. Mosquitoes infect
both monkeys and humans, causing localized outbreaks.
Nature of the disease:
Although some infections are asymptomatic, most lead to an acute
illness characterized by two phases. Initially, there is fever,
muscular pain, headache, chills, anorexia, nausea and/or vomiting,
often with bradycardia. About 15% of patients progress to a second
phase after a few days, with resurgence of fever, development of
jaundice, abdominal pain, vomiting and haemorrhagic manifestations;
half of these patients die 10-14 days after onset of illness.
Geographical distribution:
The yellow fever virus is endemic in some tropical areas of Africa and
central and south America. The number of epidemics has increased since
the early 1980s. Other countries are considered to be at risk of
introduction of yellow fever due to the presence of the vector and
suitable primate hosts (including Asia, where yellow fever has never
been reported).
Risk for travellers: Travellers are at risk in
all areas where yellow fever is endemic. The risk is greatest for
visitors who enter forest and jungle areas.
Prophylaxis (protective treatment): Vaccination. In some countries, yellow fever vaccination is mandatory for visitors.
Precautions: Avoid mosquito bites during the day as well as at night.
Endemic Countries:
The World Health Organization considers the following countries to be
endemic for yellow fever: Angola, Benin, Bolivia, Brazil, Burkino Faso,
Burundi, Cameroon, Central African Republic, Chad, Colombia, Congo,
Congo, Côte d'Ivoire, Democratic Republic of the Congo, Ecuador,
Equatorial Guinea, Ethiopia, French Guyana, Gabon, Gambia, Ghana,
Guinea, Guinea-Bissau, Guyana, Kenya, Liberia, Mali, Niger, Nigeria,
Panama, Peru, Rwanda, Sao Tome and Principe, Senegal, Sierra Leone,
Somalia, Sudan, Suriname, Togo, Trinidad and Tobago, Uganda, United
Republic of Tanzania and Venezuela.
Source: WHO.