infectious diseases
Lassa Fever
Diagnosis of Lassa Fever
Polymerase chain reaction (PCR) or serologic testing Lassa fever is suspected in patients with possible exposure if they have a viral prodrome followed by unexplained disease of any organ system. Liver tests, urinalysis, serologic tests, and complete blood count should then be done. Proteinuria is common and may be massive. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels rise (to 10 times normal), as do lactic dehydrogenase levels. The most rapid diagnostic test is PCR, but demonstrating either Lassa IgM antibodies or a 4-fold rise in IgG antibody titer using an indirect fluorescent antibody technique is also diagnostic. Although the virus can be grown in cell culture, cultures are not routine. Because infection is a risk, particularly in patients with hemorrhagic fever, cultures must be handled only in a biosafety level 4 laboratory. Chest x-rays, obtained if lung involvement is suspected, may show basilar pneumonitis and pleural effusions. 