What are common bacteria and viruses based on geography?

Common Bacteria and Viruses by Geographic Region

Geographic Distribution of Key Pathogens

Sub-Saharan Africa

Bacterial Pathogens:

• Rickettsia africae (African tick bite fever) is endemic throughout rural areas, transmitted by cattle ticks, and represents a common cause of fever in travelers returning from safaris 1
• Salmonella typhi and Salmonella paratyphi (enteric fever) are common, particularly in those visiting friends and relatives 1
• Streptococcus pneumoniae causes significant morbidity, killing approximately half a million children under 5 years old annually in this region 1
• Plague (Yersinia pestis) remains endemic with cases reported during 2000-2009 1

Viral Pathogens:

• Dengue virus is present but less prevalent than in Asia 1
• Yellow fever is endemic and requires vaccination consideration 1
• Measles remains a significant cause of mortality, with rubeola virus causing over 20 million infections worldwide in 2013 1
• Chikungunya was initially described in East Africa and remains endemic 1

South and Southeast Asia

Bacterial Pathogens:

• Rickettsia typhi (murine typhus) is found in tropical port cities and coastal regions with dense rodent populations 1
• Orientia tsutsugamushi (scrub typhus) is a significant cause of fever in rural populations, especially in Laos 1
• Burkholderia pseudomallei (melioidosis) should be investigated in patients presenting with respiratory symptoms and upper zone infiltrates 1
• Corynebacterium diphtheriae remains endemic in the Indian subcontinent due to breakdowns in immunization programs 1
• Quinolone-resistant Campylobacter isolates are increasingly reported 1

Viral Pathogens:

• Dengue is the commonest arboviral infection in returning travelers from Asia, with an annual global incidence of 50-100 million cases 1, 2
• Chikungunya has spread to large areas of south and Southeast Asia following an epidemic originating in Mauritius 1
• Japanese encephalitis is endemic and vaccine-preventable 1
• Norovirus GII is among the most prevalent enteric viruses with the highest concentration 3

Mediterranean and Middle East

Bacterial Pathogens:

• Rickettsia conorii (Mediterranean spotted fever) is transmitted by dog ticks, predominantly in urban and suburban areas of the Mediterranean and Caspian littorals 1
• Brucella species are present due to contact with livestock and unpasteurized milk 1
• Coxiella burnetii (Q fever) occurs as endemic cases or outbreaks 1

Viral Pathogens:

• Tick-borne encephalitis is restricted to central and Eastern Europe 1
• Hepatitis A is transmitted through the fecal-oral route via contaminated water and food 1

South and Central America

Bacterial Pathogens:

• Corynebacterium diphtheriae remains endemic due to immunization program breakdowns 1
• Leptospira species are present, particularly in areas with contaminated water 1

Viral Pathogens:

• Dengue is particularly prevalent, second only to Asia in global distribution 1
• Yellow fever is endemic in tropical regions 1
• Arenaviruses cause viral hemorrhagic fever 1
• Chikungunya transmission was documented in the eastern Caribbean 1

Eastern Caribbean

Bacterial Pathogens:

• Rickettsia africae is endemic in this region, transmitted by cattle ticks 1

Viral Pathogens:

• Chikungunya is present following spread from the Mauritius epidemic 1

Universal Respiratory Pathogens (All Regions)

Bacterial:

• Streptococcus pneumoniae, Haemophilus influenzae, and Group A streptococci remain the most likely upper respiratory tract pathogens globally 1
• Mycoplasma pneumoniae is the most common atypical pathogen, followed by Legionella and Chlamydia species 1
• Community-acquired MRSA (CA-MRSA) with PVL toxin has disseminated globally, causing necrotizing pneumonia 1

Viral:

• Rhinovirus (30-80% of common colds), human coronavirus (15%), respiratory syncytial virus (10-15%), and adenoviruses (5%) are distributed worldwide 1
• Influenza is the most common vaccine-preventable infection acquired by travelers globally 1

Critical Clinical Pitfalls

• Fecal indicator bacteria like E. coli and Enterococcus are not universal predictors for pathogens in tropical environments 3
• Dengue warning signs (persistent vomiting, abdominal pain, mucosal bleeding, lethargy) typically appear around day 3-7 of illness and warrant immediate hospitalization 2, 4
• Vector isolation for dengue patients must continue for 5-6 days after symptom onset, as patients remain viremic during this period 5
• Fever recurring after 4 afebrile days in dengue falls outside the expected illness pattern and mandates investigation for secondary bacterial infection 4