Comments
INITIAL SYMPTOMS:
Five phases beginning with flu-like illness and then hypotensive, oliguric, diuretic, and convalescent; The hantaviral diseases share the following: febrile prodrome, thrombocytopenia, leukocytosis, and capillary leakage. [CCDM]
FINDINGS:
In the severe disease caused by Hantaan and Dobrava viruses, five clinical phases have been described: febrile, hypotensive, oliguric, diuretic, and convalescent. Common symptoms during the febrile phase include flu-like symptoms, abdominal pain, low back pain, vomiting, facial and chest flushing, petechiae, conjunctival injection, and blurred vision. Pulmonary edema is recognized in about 10% to 20% of the cases. After appearance of the petechiae, capillary leaking and hemoconcentration are marked by elevation of the hematocrit. The ensuing shock is fatal in some cases. Renal failure for 3-7 days is followed by slow recovery. Fatal hemorrhages, usually of the CNS, occur rarely. Laboratory abnormalities after the initial phase include leukocytosis with left shift, thrombocytopenia, proteinuria, hematuria, and elevated BUN and creatinine. Case-fatality rates for this syndrome range from less than 1% for the Puumala virus to 5%-15% for the Hanta and Dobrava viruses. [CCDM, p. 245-9; ID, p. 2023-9, 2140-4] Bleeding and kidney effects can be severe (+++). Heart effects are common (++). Pulmonary and neurological effects are occasionally noted. Not typically noted are rash, jaundice, and eye effects. [Cecil, p. 2151] Rashes include petechiae on the upper trunk and an erythematous flush that blanches on pressure on the torso and face. [PPID, p. 2027] Neurological disease dominates in some cases, suggesting viral encephalitis. [Guerrant, p. 475]
EPIDEMIOLOGY:
Field rodents are the reservoir, and the virus is present in feces, urine, and saliva of infected animals. Workers are infected by inhaling dust contaminated with rodent excreta. Person-to-person transmission occurs rarely. Two of the viruses cause severe HFRS: Hantaan in East Asia and Dobrava in the Balkans. Puumala virus causes mild disease in Europe and the Balkans, and Seoul virus causes mild to severe disease worldwide. HFRS is a rural disease except for Seoul virus that infects urban rats. Seoul virus also infects laboratory rats and the technicians and scientists who handle them. An estimated 100,000 Hantaan virus infections occur in China each year. Dobrava virus infects a few hundred people a year. Exposure usually occurs indoors where mice live or search for food. The highest infection rates are in workers who have contact with mice. [CCDM, p. 245-9; ID, p. 2023-9, 2140-4] This virus does not replicate to high concentrations in cell cultures, and, therefore, is not likely to be used as a biological weapon. [JAMA] Puumala virus causes asymptomatic infections in up to 90% of cases. The disease is called nephropathia epidemica, which is rarely hemorrhagic. Seoul virus causes mild to moderately severe HFRS in Eurasia, and hepatic involvement is prominent. [PPID, p. 2028]
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