Lassa virus is a linear, bisegmented, single-stranded RNA virus, which belong to the Arenaviridae family that causes viral hemorrhagic fever transmitted by rats. The virus is endemic in West African countries, which may be due to its zoonotic nature. Lassa virus infection occurs through contact with the vector Mastomys natalensis or infected humans and can lead to wide symptoms from a mild infection to Lassa fever and to a severe fatal viral hemorrhagic fever, which include delayed cellular immunity resulting to fulminant viremia. The virus replicates through a strategy known as the Ambisense, where two RNA strands code for genes in both the sense and antisense direction that is rapid and demonstrate temporal control in replication. Different diagnostic tests for the virus are available, which range from viral culture to serological and molecular diagnostic tests. There is an urgent need to develop drugs and vaccines against the virus because the World Health Organization (WHO) has identified Lassa virus as one of the viruses that is likely to cause a future epidemic, although a research is ongoing to evaluate Lassa virus vaccine immunogenicity in the CBA/J-ML29 mouse model. This chapter gives an overview on the structure, replication cycle, pathogenesis, and diagnosis of the virus.
Part of the book: Current Topics in Tropical Emerging Diseases and Travel Medicine
Hepatitis B virus (HBV) is a double-stranded circular DNA virus that infects the hepatocytes. HBV infection is considered as an important public health concern globally especially with one-third of the world’s population been infected. Local and international migrants are one of those population at high risk of the infection. Many factors interplay in the acquisition of HBV such as purpose of travel, destination endemicity rate of the virus, time of stay of the traveler, inadequate prevention and control measures, among others, understanding the genotypes of HBV is critical in correlating the evolution of the virus and migration of humans and also treatment responses of infected population. The symptom of the virus ranges from fever to jaundice and to a liver cirrhosis and hepatocellular carcinoma (HCC). Transmission of HBV is commonly via horizontal route in developing regions and in the developed regions; transmission occur more often among adults that use injectable drugs and high-risk sexual behaviors. Therefore, the Centers for Disease Control and Prevention (CDC) and World Health Organization (WHO) have recommended HBV screening and vaccination to all travelers without an HBV immunization history before traveling to endemic regions. This chapter gives an overview on HBV as a potential traveler’s infection.
Part of the book: Tourism