Malaria in humans is caused by one of four protozoan species of the genus Plasmodium: P. falciparum, P. vivax, P. ovale, or P. malariae. All species are transmitted by the bite of an infected female Anopheles mosquito. Occasionally, transmission occurs by blood transfusion or congenitally from mother to fetus. Although malaria can be a fatal disease, illness and death from malaria are largely preventable.

Yellow fever is a mosquito-borne viral disease. Illness ranges in severity from an influenza-like syndrome to severe hepatitis and hemorrhagic fever. Yellow fever is caused by a zoonotic virus that is maintained in nature by transmission between nonhuman primates and mosquito vectors. In some situations, humans may serve as the primary host in the transmission cycle ("urban yellow feverÓ").

Diphtheria is an acute bacterial disease involving primarily the tonsils, pharynx, larynx, nose, skin, and occasionally other mucous membranes. The characteristic lesion is marked by a patch or patches of an adherent grayish membrane with a surrounding inflammation.

Tetanus is an acute disease characterized by muscle rigidity and painful spasms, often starting in the muscles of the jaw and neck. The disease is caused by neurotoxin produced by anaerobic tetanus bacilli growing in contaminated wounds. Lesions that are considered Òtetanus proneÓ are wounds contaminated with dirt, feces or saliva, deep wounds, or those with necrotic tissue. However, tetanus has been associated with apparently clean superficial wounds, surgical procedures, insect bites, dental infections, chronic sores and infections, and intravenous drug use. In 5%Ð10% of reported cases in the United States, no antecedent wound was identified.

Pertussis is an acute bacterial disease involving the respiratory tract, characterized by prolonged paroxysmal coughing. Persons in all age groups can be infected. Complications and deaths from pertussis are most common among infants.

Hepatitis A is a liver disease caused by the hepatitis A virus (HAV). Hepatitis A can affect anyone. In the United States, hepatitis A can occur in situations ranging from isolated cases of disease to widespread epidemics.

Hepatitis B is a serious disease caused by a virus that attacks the liver. The virus, which is called hepatitis B virus (HBV), can cause lifelong infection, cirrhosis (scarring) of the liver, liver cancer, liver failure, and death.

Typhoid fever is an acute, life-threatening febrile illness caused by the bacterium Salmonella enterica Typhi.

Rabies is a preventable viral disease of mammals most often transmitted through the bite of a rabid animal. The vast majority of rabies cases reported to the Centers for Disease Control and Prevention (CDC) each year occur in wild animals like raccoons, skunks, bats, and foxes. Domestic animals account for less than 10% of the reported rabies cases, with cats, cattle, and dogs most often reported rabid.

Rabies virus infects the central nervous system, causing encephalopathy and ultimately death. Early symptoms of rabies in humans are nonspecific, consisting of fever, headache, and general malaise. As the disease progresses, neurological symptoms appear and may include insomnia, anxiety, confusion, slight or partial paralysis, excitation, hallucinations, agitation, hypersalivation, difficulty swallowing, and hydrophobia (fear of water). Death usually occurs within days of the onset of symptoms.

Meningitis is an infection of the fluid of a person's spinal cord and the fluid that surrounds the brain. People sometimes refer to it as spinal meningitis. Meningitis is usually caused by a viral or bacterial infection. Knowing whether meningitis is caused by a virus or bacterium is important because the severity of illness and the treatment differ. Viral meningitis is generally less severe and resolves without specific treatment, while bacterial meningitis can be quite severe and may result in brain damage, hearing loss, or learning disability. For bacterial meningitis, it is also important to know which type of bacteria is causing the meningitis because antibiotics can prevent some types from spreading and infecting other people. Before the 1990s, Haemophilus influenzae type b (Hib) was the leading cause of bacterial meningitis, but new vaccines being given to all children as part of their routine immunizations have reduced the occurrence of invasive disease due to H. influenzae. Today, Streptococcus pneumoniae and Neisseria meningitidis are the leading causes of bacterial meningitis.

More health informations for travellers can be found there : http://www.cdc.gov/travel/