Pathology, Doelstellingen blok 3.2
Description tropical infectious diseases:
-Infectious diseases found only in tropical or subtropical areas (rare)
-Diseases which are more widespread in the tropics
-Diseases which are more difficult to prevent or control in the tropics
Immunization:
-Passive: antibodies are injected, short term protected
-Active: you make antibodies yourself, often lifelong immunity
Ebola
Pathogen (ziekteverwekker)
Virus
Route of infection (route van besmetting)
It is thought that fruit bats of the Pteropodidae family are natural Ebola virus hosts. Ebola is
introduced into the human population through close contact with the blood, secretions, organs or
other bodily fluids of infected animals such as chimpanzees, gorillas, fruit bats, monkeys, forest
antelope and porcupines found ill or dead or in the rainforest.
Ebola then spreads through human-to-human transmission via direct contact (through broken skin or
mucous membranes) with the blood, secretions, organs or other bodily fluids of infected people, and
with surfaces and materials (e.g. bedding, clothing) contaminated with these fluids.
Health-care workers have frequently been infected while treating patients with suspected or
confirmed EVD. This has occurred through close contact with patients when infection control
precautions are not strictly practiced.
Burial ceremonies in which mourners have direct contact with the body of the deceased person can
also play a role in the transmission of Ebola.
People remain infectious as long as their blood and body fluids, including semen and breast milk,
contain the virus. Men who have recovered from the disease can still transmit the virus through their
semen for up to 7 weeks after recovery from illness.
Incubation period (incubatietijd)
The incubation period, that is, the time interval from infection with the virus to onset of symptoms is
2 to 21 days. Humans are not infectious until they develop symptoms. First symptoms are the sudden
onset of fever fatigue, muscle pain, headache and sore throat. This is followed by vomiting,
diarrhoea, rash, symptoms of impaired kidney and liver function, and in some cases, both internal
and external bleeding (e.g. oozing from the gums, blood in the stools). Laboratory findings include
low white blood cell and platelet counts and elevated liver enzymes.
Clinical picture (klinisch beeld)
It can be difficult to distinguish EVD from other infectious diseases such as malaria, typhoid fever and
meningitis. Confirmation that symptoms are caused by Ebola virus infection are made using the
following investigations:
,-antibody-capture enzyme-linked immunosorbent assay (ELISA)
-antigen-capture detection tests
-serum neutralization test
-reverse transcriptase polymerase chain reaction (RT-PCR) assay
-electron microscopy
-virus isolation by cell culture.
Samples from patients are an extreme biohazard risk; laboratory testing on non-inactivated samples
should be conducted under maximum biological containment conditions.
Therapy
Supportive care-rehydration with oral or intravenous fluids- and treatment of specific symptoms,
improves survival. There is as yet no proven treatment available for EVD. However, a range of
potential treatments including blood products, immune therapies and drug therapies are currently
being evaluated. No licensed vaccines are available yet, but 2 potential vaccines are undergoing
human safety testing.
Prevention
Good outbreak control relies on applying a package of interventions, namely case management,
surveillance and contact tracing, a good laboratory service, safe burials and social mobilisation.
Community engagement is key to successfully controlling outbreaks. Raising awareness of risk factors
for Ebola infection and protective measures that individuals can take is an effective way to reduce
human transmission. Risk reduction messaging should focus on several factors:
-Reducing the risk of wildlife-to-human transmission from contact with infected fruit bats or
monkeys/apes and the consumption of their raw meat. Animals should be handled with gloves and
other appropriate protective clothing. Animal products (blood and meat) should be thoroughly
cooked before consumption.
-Reducing the risk of human-to-human transmission from direct or close contact with people with
Ebola symptoms, particularly with their bodily fluids. Gloves and appropriate personal protective
equipment should be worn when taking care of ill patients at home. Regular hand washing is
required after visiting patients in hospital, as well as after taking care of patients at home.
-Outbreak containment measures including prompt and safe burial of the dead, identifying people
who may have been in contact with someone infected with Ebola, monitoring the health of contacts
for 21 days, the importance of separating the healthy from the sick to prevent further spread, the
importance of good hygiene and maintaining a clean environment.
Dengue (knokkelkoorts)
Pathogen (ziekteverwekker)
virus. Dengue is a mosquito-borne infection found in tropical and sub-tropical regions around the
, world. In recent years, transmission has increased predominantly in urban and semi-urban areas and
has become a major international public health concern.
Route of infection (route van besmetting)
The Aedes aegypti mosquito is the primary vector of dengue. The virus is transmitted to humans
through the bites of infected female mosquitoes. After virus incubation for 4–10 days, an infected
mosquito is capable of transmitting the virus for the rest of its life.
Infected humans are the main carriers and multipliers of the virus, serving as a source of the virus for
uninfected mosquitoes. Patients who are already infected with the dengue virus can transmit the
infection (for 4–5 days; maximum 12) via Aedes mosquitoes after their first symptoms appear.
The Aedes aegypti mosquito lives in urban habitats and breeds mostly in man-made containers.
Unlike other mosquitoes Ae. aegypti is a daytime feeder; its peak biting periods are early in the
morning and in the evening before dusk. Female Ae. aegypti bites multiple people during each
feeding period.
Aedes albopictus, a secondary dengue vector in Asia, has spread to North America and Europe largely
due to the international trade in used tyres (a breeding habitat) and other goods (e.g. lucky bamboo).
Ae. albopictus is highly adaptive and therefore can survive in cooler temperate regions of Europe. Its
spread is due to its tolerance to temperatures below freezing, hibernation, and ability to shelter in
microhabitats.
Incubation period (incubatietijd)
Symptoms usually last for 2–7 days, after an incubation period of 4–10 days after the bite from an
infected mosquito.
Clinical picture (klinisch beeld)
Dengue fever is a severe, flu-like illness that affects infants, young children and adults, but seldom
causes death.
Dengue should be suspected when a high fever (40°C/ 104°F) is accompanied by two of the following
symptoms: severe headache, pain behind the eyes, muscle and joint pains, nausea, vomiting, swollen
glands or rash. Symptoms usually last for 2–7 days, after an incubation period of 4–10 days after the
bite from an infected mosquito.
Severe dengue is a potentially deadly complication due to plasma leaking, fluid accumulation,
respiratory distress, severe bleeding, or organ impairment. Warning signs occur 3–7 days after the
first symptoms in conjunction with a decrease in temperature (below 38°C/ 100°F) and include:
severe abdominal pain, persistent vomiting, rapid breathing, bleeding gums, fatigue, restlessness,
blood in vomit. The next 24–48 hours of the critical stage can be lethal; proper medical care is
needed to avoid complications and risk of death.
Therapy
There is no specific treatment for dengue fever.
Description tropical infectious diseases:
-Infectious diseases found only in tropical or subtropical areas (rare)
-Diseases which are more widespread in the tropics
-Diseases which are more difficult to prevent or control in the tropics
Immunization:
-Passive: antibodies are injected, short term protected
-Active: you make antibodies yourself, often lifelong immunity
Ebola
Pathogen (ziekteverwekker)
Virus
Route of infection (route van besmetting)
It is thought that fruit bats of the Pteropodidae family are natural Ebola virus hosts. Ebola is
introduced into the human population through close contact with the blood, secretions, organs or
other bodily fluids of infected animals such as chimpanzees, gorillas, fruit bats, monkeys, forest
antelope and porcupines found ill or dead or in the rainforest.
Ebola then spreads through human-to-human transmission via direct contact (through broken skin or
mucous membranes) with the blood, secretions, organs or other bodily fluids of infected people, and
with surfaces and materials (e.g. bedding, clothing) contaminated with these fluids.
Health-care workers have frequently been infected while treating patients with suspected or
confirmed EVD. This has occurred through close contact with patients when infection control
precautions are not strictly practiced.
Burial ceremonies in which mourners have direct contact with the body of the deceased person can
also play a role in the transmission of Ebola.
People remain infectious as long as their blood and body fluids, including semen and breast milk,
contain the virus. Men who have recovered from the disease can still transmit the virus through their
semen for up to 7 weeks after recovery from illness.
Incubation period (incubatietijd)
The incubation period, that is, the time interval from infection with the virus to onset of symptoms is
2 to 21 days. Humans are not infectious until they develop symptoms. First symptoms are the sudden
onset of fever fatigue, muscle pain, headache and sore throat. This is followed by vomiting,
diarrhoea, rash, symptoms of impaired kidney and liver function, and in some cases, both internal
and external bleeding (e.g. oozing from the gums, blood in the stools). Laboratory findings include
low white blood cell and platelet counts and elevated liver enzymes.
Clinical picture (klinisch beeld)
It can be difficult to distinguish EVD from other infectious diseases such as malaria, typhoid fever and
meningitis. Confirmation that symptoms are caused by Ebola virus infection are made using the
following investigations:
,-antibody-capture enzyme-linked immunosorbent assay (ELISA)
-antigen-capture detection tests
-serum neutralization test
-reverse transcriptase polymerase chain reaction (RT-PCR) assay
-electron microscopy
-virus isolation by cell culture.
Samples from patients are an extreme biohazard risk; laboratory testing on non-inactivated samples
should be conducted under maximum biological containment conditions.
Therapy
Supportive care-rehydration with oral or intravenous fluids- and treatment of specific symptoms,
improves survival. There is as yet no proven treatment available for EVD. However, a range of
potential treatments including blood products, immune therapies and drug therapies are currently
being evaluated. No licensed vaccines are available yet, but 2 potential vaccines are undergoing
human safety testing.
Prevention
Good outbreak control relies on applying a package of interventions, namely case management,
surveillance and contact tracing, a good laboratory service, safe burials and social mobilisation.
Community engagement is key to successfully controlling outbreaks. Raising awareness of risk factors
for Ebola infection and protective measures that individuals can take is an effective way to reduce
human transmission. Risk reduction messaging should focus on several factors:
-Reducing the risk of wildlife-to-human transmission from contact with infected fruit bats or
monkeys/apes and the consumption of their raw meat. Animals should be handled with gloves and
other appropriate protective clothing. Animal products (blood and meat) should be thoroughly
cooked before consumption.
-Reducing the risk of human-to-human transmission from direct or close contact with people with
Ebola symptoms, particularly with their bodily fluids. Gloves and appropriate personal protective
equipment should be worn when taking care of ill patients at home. Regular hand washing is
required after visiting patients in hospital, as well as after taking care of patients at home.
-Outbreak containment measures including prompt and safe burial of the dead, identifying people
who may have been in contact with someone infected with Ebola, monitoring the health of contacts
for 21 days, the importance of separating the healthy from the sick to prevent further spread, the
importance of good hygiene and maintaining a clean environment.
Dengue (knokkelkoorts)
Pathogen (ziekteverwekker)
virus. Dengue is a mosquito-borne infection found in tropical and sub-tropical regions around the
, world. In recent years, transmission has increased predominantly in urban and semi-urban areas and
has become a major international public health concern.
Route of infection (route van besmetting)
The Aedes aegypti mosquito is the primary vector of dengue. The virus is transmitted to humans
through the bites of infected female mosquitoes. After virus incubation for 4–10 days, an infected
mosquito is capable of transmitting the virus for the rest of its life.
Infected humans are the main carriers and multipliers of the virus, serving as a source of the virus for
uninfected mosquitoes. Patients who are already infected with the dengue virus can transmit the
infection (for 4–5 days; maximum 12) via Aedes mosquitoes after their first symptoms appear.
The Aedes aegypti mosquito lives in urban habitats and breeds mostly in man-made containers.
Unlike other mosquitoes Ae. aegypti is a daytime feeder; its peak biting periods are early in the
morning and in the evening before dusk. Female Ae. aegypti bites multiple people during each
feeding period.
Aedes albopictus, a secondary dengue vector in Asia, has spread to North America and Europe largely
due to the international trade in used tyres (a breeding habitat) and other goods (e.g. lucky bamboo).
Ae. albopictus is highly adaptive and therefore can survive in cooler temperate regions of Europe. Its
spread is due to its tolerance to temperatures below freezing, hibernation, and ability to shelter in
microhabitats.
Incubation period (incubatietijd)
Symptoms usually last for 2–7 days, after an incubation period of 4–10 days after the bite from an
infected mosquito.
Clinical picture (klinisch beeld)
Dengue fever is a severe, flu-like illness that affects infants, young children and adults, but seldom
causes death.
Dengue should be suspected when a high fever (40°C/ 104°F) is accompanied by two of the following
symptoms: severe headache, pain behind the eyes, muscle and joint pains, nausea, vomiting, swollen
glands or rash. Symptoms usually last for 2–7 days, after an incubation period of 4–10 days after the
bite from an infected mosquito.
Severe dengue is a potentially deadly complication due to plasma leaking, fluid accumulation,
respiratory distress, severe bleeding, or organ impairment. Warning signs occur 3–7 days after the
first symptoms in conjunction with a decrease in temperature (below 38°C/ 100°F) and include:
severe abdominal pain, persistent vomiting, rapid breathing, bleeding gums, fatigue, restlessness,
blood in vomit. The next 24–48 hours of the critical stage can be lethal; proper medical care is
needed to avoid complications and risk of death.
Therapy
There is no specific treatment for dengue fever.
