This chapter provides an overview of some of the newly recognised and emerging ocular infections. Rickettsioses are zoonoses due to obligate intracellular small gram-negative bacteria. Most of them are transmitted to humans by the bite of contaminated arthropods, such as ticks. Rickettsial agents are classified into three major categories: the spotted fever group, the typhus group, and the scrub typhus. The spotted fever group includes Mediterranean spotted fever (MSF), Rocky Mountain spotted fever (RMSF), and numerous other rickettsioses. For most of the organisms of the spotted fever and typhus groups, the target cells are the endothelial cells of blood vessels. A rickettsial disease should be suspected, during spring or summer, in the presence of the triad of high fever, headache and general malaise, and skin rash in a patient living in or traveling back from a region endemic for rickettsioses. Ocular involvement is common in patients with rickettsiosis. Non-granulomatous anterior uveitis without or with associated posterior segment involvement has been described with rickettsioses. Retinochoroidal involvement is common in patients with rickettsioses. In a recent prospective study, more than 80% of patients with acute MSF examined by ophthalmoscopy and fluorescein angiography had chorioretinal involvement, which was frequently asymptomatic. Retinitis is observed in at least 30% of patients with acute MSF. An associated mild or moderate vitreous inflammation is commonly observed. Fluorescein angiography shows early hypofluorescence and late staining of large acute white retinal lesions and isofluorescence or moderate hypofluorescence of small active retinal lesions throughout the whole phase of dye transit. The West Nile virus (WNV), first isolated in 1937 in the West Nile district of Uganda, is an enveloped single-stranded RNA flavivirus. It is a member of the Japanese encephalitis virus serocomplex, which includes Japanese encephalitis virus, Saint Louis encephalitis virus, Murray Valley encephalitis virus, and Kunjin virus. Symptoms of affected patients include high-grade fever, headache, myalgia, arthralgia, malaise, nausea, vomiting, skin rash, weakness, and pharyngitis. Ocular involvement in dengue fever has recently been reported from Singapore, Thailand, Taiwan, India, Mexico, and Brazil. The ocular symptoms my range from mild blurring of vision to catastrophic and severe blindness and they usually occur within a month of the dengue infection.