in 2000 , the naval medical research center detachment ( nmrcd ) and the ministry of health of peru established a passive surveillance study to determine arboviral causes of febrile illness ( protocol nmrcd.2000.0006 ) . patients with acute , undifferentiated febrile illness of < 7 days were invited to enroll , and demographic and clinical information was obtained at the time of enrollment . blood samples were obtained and assayed by virus isolation , and convalescent - phase samples were obtained 10 days to 4 weeks later for serologic studies . patient 1 was a 7-year - old girl from san benito , a rural community near yurimaguas city ( figure 1 ) , who on june 19 , 2006 , was noted to have nasal congestion , sneezing , chills , malaise , myalgia , abdominal pain , and fever followed by several episodes of watery , nonbloody feces , and vomiting . the next day the involuntary movement and vomiting stopped ; however , other signs worsened and she became somnolent and prostrate . later that day she was admitted to the hospital santa gema of yurimaguas with fever , dehydration , stupor , and signs of respiratory distress along with tonic temperature was 40c ( 104f ) , blood pressure 90/50 mm hg , respiratory rate markedly increased , and heart rate 132 beats / min . distal cyanosis , nasal flaring , rhonchi without crackles , and supraclavicular and intercostal retractions were noted , but no jaundice , lymphadenopathy or conjunctival hemorrhage were observed . hepatomegaly ( liver 4 cm under the costal border ) , stupor , and neck stiffness were also noted . laboratory test results showed a left shift in the leukocyte count and renal failure ( table 1 ) . later that day the patient was considered to have a complicated , febrile , neurologic illness , and a blood sample was sent for advanced analysis at the nmrcd in lima , peru , and the national institute of health of peru . selected sites in peru of passive surveillance study to determine arboviral causes of febrile illness in peru , established in 2000 by naval medical research center detachment and the ministry of health of peru ( protocol nmrcd.2000.0006 ) . sites shown include those of 2 patients with evidence of acute venezuelan equine encephalitis virus infection . the girl was given supportive therapy with broad spectrum antibiotics , intravenous hydration , oxygen , and anticonvulsive medications ( diazepam , phenytoin ) . on june 21 , seizures persisted , and the patient became comatose and later died of respiratory arrest . arterial blood gasses and electrolytes could not be measured because of the limited capacity of the hospital laboratory . the girl s parents did not consent to lumbar puncture or autopsy . examination of the girl s serum in vero cells identified veev , and sequencing and phylogenetic analyses using previously described methods further identified it as subtype i d panama / peru genotype ( figure 2 ) ( 15 ) . on the day the serum was collected ( 1 day after onset of signs ) , viremia titer was 1.8 10 pfu / ml , similar to titers from other veev - infected study patients who did not have neurologic complications ( table 2 ) . the national institute of health reported the sample to be negative for leptospiral and rickettsial organisms , according to elisa immunoglobulin ( ig ) m and indirect immunofluorescent assays , respectively . neighbor - joining phylogenetic tree of venezuelan equine encephalitis virus ( veev ) complex based on partial sequence of the pe2 segment ( nucleotide positions 83859190 of the veev genome ) . the tree was rooted by using an outgroup of 3 major lineages of eastern equine encephalitis virus ( eeev ) . the strain isolated from a 7-year - old girl who died from acute veev infection in peru , june 21 , 2006 , is in boldface . viruses are labeled by code designation , abbreviated location name , year of isolation ( last 2 digits of year only ) , and genbank accession numbers of the corresponding sequences . pa , panama ; gu , guatemala ; mx , mexico ; fg , french guiana ; ve , venezuela ; br , brazil ; ag , argentina ; pe , peru ; fl , florida . patient 2 was a 25-year - old man from puerto maldonado , a city in the department of madre de dios ( figure 1 ) . on february 24 , 2005 , he reported fever , headache , myalgia , nausea , vomiting , and diarrhea . because he was from an outlying rural area , he was taken to the local health center where he received intravenous rehydration and partially recovered . the patient stayed at home , but his signs and symptoms persisted . on february 27 , jaundice and epistaxis developed , and the local health center referred him to the santa rosa hospital in puerto maldonado , where he was admitted on february 28 . the patient s status deteriorated quickly ; hematuria and hematemesis were followed by liver and renal failure ( table 1 ) , and the patient died on march 1 . postmortem examination found multiple hemorrhages in his lungs , kidneys , and stomach . a serum sample collected at the time of admission was positive for veev antibodies , according to elisa igm ( titer 6,400 ) ( 2,3 ) . serologic assays produced negative results for leptospiral and arboviral diseases , including dengue , mayaro , yellow fever , oropouche , and eastern equine encephalitis . veev subtype i d infection ( panama / peru genotype ) was confirmed . because her viremia titer was similar to titers of other patients who did not have neurologic complications and survived veev infection , although veev was isolated from the patient s serum and she met the centers for disease control and prevention s diagnostic criteria for confirmed vee ( www.cdc.gov/ncphi/disss/nndss/casedef/arboviral_current.htm ) , we can not rule out concomitant bacterial meningitis in this patient , who had meningismus and leukocytosis . the limited extent of our diagnostic procedures prevent us from concluding with certainty that veev infection was the main cause of death . although an uncommon manifestation of veev infection , these complications have been reported elsewhere ( 6,8,14 ) . to date , only veev subtype i d has been isolated in and around puerto maldonado ( 5 ) ; thus , this patient was probably also infected with this subtype . however , we can not unequivocally state that the patient died from veev infection . both fatal cases described in this report were clinically similar to previously reported enzootic and epidemic vee cases ( 1,6,8,9,11,14 ) . initially , both patients had fever , body aches , vomiting , and diarrhea ( table 1 ) ( 1 , 6,8,9,11 ) , which are also caused by other tropical diseases like dengue . only some patients , such as patient 1 from yurimaguas , had neurologic complications ( table 1 ) , which are more commonly observed in children<15 years of age ( 6,8,9,11 ) . our surveillance activities were limited to only 8 surveillance sites in peru ( figure 1 ) , so vee cases in other areas may remain undiagnosed . because of the lack of surveillance activities and proper diagnostic capabilities , fatal veev infection in peru is likely ; many cases may remain underreported in isolated rural locations where the disease is most common . additional studies are needed to fully measure the extent and effects of vee in peru .
studies have suggested that enzootic strains of venezuelan equine encephalitis ( vee ) subtype i d in the amazon region , peru , may be less pathogenic to humans than are epizootic variants . 
 deaths of 2 persons with evidence of acute vee virus infection indicate that fatal veev infection in peru is likely . cases may remain underreported .