Typhoid Fever
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. [+] Show All Plague
Cause:
The plague bacillus, Yersinia pestis.
Transmission:
Plague is a zoonotic disease affecting rodents and transmitted by fleas from rodents to other animals and to humans. Direct person-to-person transmission does not occur except in the case of pneumonic plague, when respiratory droplets may transfer the infection from the patient to others in close contact. [+] Show All Meningococcal disease
Cause:
The bacterium Neisseria meningitidis, of which 12 serogroups are known. Most cases of meningococcal disease are caused by serogroups A, B and C; less commonly, infection is caused by serogroups Y and W-135. Epidemics in Africa are usually caused by N. meningitidis type A.
Transmission:
occurs by direct person-to-person contact, including aerosol transmission and respiratory droplets from the nose and pharynx of infected persons, patients or carriers. There is no animal reservoir or insect vector. [+] Show All 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. [+] Show All 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. [+] Show All Hepatitis E
Cause:
Hepatitis E virus, which has not yet been definitively classified (formerly classified as Caliciviridae).
Transmission:
Hepatitis E is a waterborne disease usually acquired from contaminated drinking water. Direct faecal-oral transmission from person to person is also possible. There is no insect vector. It is suspected, but not proved, that hepatitis E may have a domestic animal reservoir host, such as pigs. [+] Show All 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). [+] Show All Cholera
Cause:
Vibrio cholerae bacteria, serogroups O1 and O139.
Transmission:
Infection occurs through ingestion of food or water contaminated directly or indirectly by faeces or vomit of infected persons. Cholera affects only humans; there is no insect vector or animal reservoir host. [+] Show All 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. [+] Show All |
