Chapare Hemorrhagic Fever and Virus Detection in Rodents in Bolivia in 2019.

BACKGROUND: In June 2019, the Bolivian Ministry of Health reported a cluster of cases of hemorrhagic fever that started in the municipality of Caranavi and expanded to La Paz. The cause of these cases was unknown. METHODS: We obtained samples for next-generation sequencing and virus isolation. Human and rodent specimens were tested by means of virus-specific real-time quantitative reverse-transcriptase-polymerase-chain-reaction assays, next-generation sequencing, and virus isolation. RESULTS: Nine cases of hemorrhagic fever were identified; four of the patients with this illness died. The etiologic agent was identified as Mammarenavirus Chapare mammarenavirus, or Chapare virus (CHAPV), which causes Chapare hemorrhagic fever (CHHF). Probable nosocomial transmission among health care workers was identified. Some patients with CHHF had neurologic manifestations, and those who survived had a prolonged recovery period. CHAPV RNA was detected in a variety of human body fluids (including blood; urine; nasopharyngeal, oropharyngeal, and bronchoalveolar-lavage fluid; conjunctiva; and semen) and in specimens obtained from captured small-eared pygmy rice rats (Oligoryzomys microtis). In survivors of CHHF, viral RNA was detected up to 170 days after symptom onset; CHAPV was isolated from a semen sample obtained 86 days after symptom onset. CONCLUSIONS: M. Chapare mammarenavirus was identified as the etiologic agent of CHHF. Both spillover from a zoonotic reservoir and possible person-to-person transmission were identified. This virus was detected in a rodent species, O. microtis. (Funded by the Bolivian Ministry of Health and others.).

Seminario Fiebre Hemorrágica Argentina en Provincia de Buenos Aires: nuestro desafío

Destinado a todo el personal de salud, Alejandra Rodríguez aborda aspectos epidemiológicos de la Fiebre Hemorrágica Argentina, la Dra. Andrea Uboldi diserta sobre la vacuna y la Dra. Alejandra Gaiano sobre los desafíos futuros

Reactive astrogliosis in response to hemorrhagic fever virus: microarray profile of Junin virus-infected human astrocytes.

BACKGROUND: Arenavirus Junin is the causative agent of Argentine hemorrhagic fever. Limited information is available concerning the pathogenesis of this human disease, especially the pathogenesis of acute and late neurological symptoms. METHODS: In our study we present for the first time cDNA microarray profile of human astrocytes infected with the virulent strain of Junin virus. Transcriptional profiling was confirmed by quantitative real-time RT-PCR and cytokine/chemokine/growth factor assay. RESULTS: We demonstrated the impact of virus infection on immune/inflammatory response/interferon signaling and apoptosis. Pro-apoptotic response and amplification with time of pro-inflammatory cascade of human astrocytes suggested neurodegenerative dysfunctional reactive astrogliosis in response to Junin virus infection. CONCLUSION: Our results suggest potential pathogenic role of astroglial cells in the development of neurological symptoms and late neurological syndrome during Argentine hemorrhagic fever.

Latin American hemorrhagic fever.

Several viral and bacterial agents are responsible for hemorrhagic fever in Latin America, but there are three agents that are only present in this region: (1) the Junin virus, (2) the Machupo virus, and (3) the Guanaritovirus, members of the Tacaribe complex of the family Arenaviridae and responsible for the Argentinian, Bolivian, and Venezuelan hemorrhagic fever. The clinical manifestations of hemorrhagic fever are similar for the three viruses, mainly myalgia, arthralgia, headache, relative bradycardia, conjunctivitis, nausea, vomiting, diarrhea, and hemorrhagic disorders. In this article, the three viruses, their causes, and manifestations are discussed.

Pichinde virus-induced respiratory failure due to obstruction of the small airways: structure and function.

Respiratory distress that leads to death is seen in patients with Lassa fever. The development of this respiratory problem was studied using a Pichinde virus model (10(4) plaque forming units, IP, survival time 20 +/- 1 days) in strain 13 guinea pigs (n = 35, 229-353 g) of this lethal human contagious infectious disease. Extravascular lung water to bloodless dry lung weight (EVLW/BDLW) ratio showed a modest yet significant increase in animals 13 and 18-21 days postinoculation (PI). In contrast, residual lung blood and lung radioactive 125I-labeled human serum albumin activity index were elevated only in the 18- to 21-day group. These data are consistent with the progressive severity of perivascular edema, lymphocytic pneumonitis, and some alveolar protein between days 13 and 18-21 PI. Lymphocytic pneumonitis appeared to be distributed near most airways and was proportional to the degree of Pichinde virus antigen staining of alveolar macrophages, large mononuclear cells within the pulmonary vascular and extravascular spaces, and alveolar-capillary membranes. These findings suggest that lymphocyte recruitment to the lung reflects the Pichinde virus-induced cell-mediated immune response. Obstructed small bronchi with some lumenal cell debris and hypertrophied epithelial cells were found associated with the areas of marked pneumonitis. The severe hypoxemia and modest anaerobic metabolism in association with marked tachypnea and normocapnia are consistent with small airway obstruction and wasted ventilation, since no change in arterial blood pressure, heart rate, hematocrit, hemoglobin, or blood volume was noted. These data suggest that Pichinde virus-induced respiratory failure was due to obstruction of the small airways with wasted ventilation in association with lymphocytic pneumonitis.

Correlation between cyclophosphamide-induced viral susceptibility and depletion of Junin virus-induced suppressor populations.

In contrast to lymphocytic choriomeningitis virus, another arenavirus, Junin virus (JV), the etiologic agent of Argentine hemorrhagic fever, when inoculated into suckling mice, induces lethal meningoencephalitis characterized by a delayed-type hypersensitivity (DTH)-like immune response. However, the adult BALB/c mouse is resistant to infection and no DTH reaction can be seen. This different viral sensitivity may be related to the development of an antigen non-specific DTH-suppressor cell pathway at work in the adult mouse. When the resistant mice are treated with cyclophosphamide (Cy) (50 mg/kg each dose) given at days -1,+1,+4 (zero: infection day), animals become susceptible and develop DTH reaction in brain that leads to death. We analyze the influence of the timing of Cy administration on the suppressor system developing after infection. It was found that Cy depletes the previously described JV-induced suppressor populations (Tsv) but a new suppressor cell (Tsv*) is disclosed bearing the Thy 1+ Ly1+2- phenotype which is unable to depress DTH in Cy-treated animals. With only two doses of Cy corresponding to days -1 and +1, the target of Tsv* cells is depleted but the third dose is still required to achieve full depletion of Tsv cells which are able to employ the Cy-resistant antigen-specific suppressor cells as targets. Since the Cy treatment is able to deplete the Tsv population together with the target of Tsv* cells, animals became unable to regulate lethal DTH reaction. Thus, a cellular explanation for an empirically established Cy schedule able to abrogate the adult mouse resistance to JV is proposed.

Venezuelan haemorrhagic fever.

An outbreak of severe haemorrhagic illness began in the municipality of Guanarito, Portuguesa State, Venezuela, in September, 1989. Subsequent detailed study of 15 cases confirmed the presence of a new viral disease, designated Venezuelan haemorrhagic fever. Characteristic features are fever, toxicity, headache, arthralgia, diarrhoea, conjunctivitis, pharyngitis, leucopenia, thrombocytopenia, and haemorrhagic manifestations. Other features include facial oedema, cervical lymphadenopathy, nausea/vomiting, cough, chest or abdominal pain, and convulsions. The patients ranged in age from 6 to 54 years; all were residents of rural areas in central Venezuela, and 9 died. Infection with Guanarito virus, a newly recognised arenavirus, was shown by direct culture or by serological confirmation in all cases. Epidemiological studies suggest that the disease is endemic in some rural areas of central Venezuela and that it is rodent-borne. Venezuelan haemorrhagic fever has many similarities to Lassa fever and to the arenavirus haemorrhagic fevers that occur in Argentina and Bolivia.

Astrocytic reaction predominance in chronic encephalitis of Junin virus-infected rats.

Junin virus antigen distribution and astrocytic reaction to prolonged infection were characterized in rat brain by the PAP technique. During the acute stage of neurologic disease following intracerebral inoculation, Junin antigen was detected in 100% of animals, strongly in most neurons but also to a much lesser degree in scattered astrocytes, dropping to 20% of rats at 540 days postinfection. Initially labeled in all brain areas, viral antigen gradually disappeared from hippocampus but persisted irregularly in cerebral cortex, basal ganglia, Purkinje cells, pons, and medulla oblongata. Such a pattern suggests that specific neuronal subpopulations, in spite of apparently unaltered cell morphology, may persistently harbor the virus, leading on occasion to a delayed neurologic syndrome. During both the acute and chronic stages of disease, a mild inflammatory exudate was observed, characterized by the presence of T and B lymphocytes, as well as macrophages and unidentified round cells. GFAP immunostaining showed increased astrocytic reaction as infection lapsed into chronicity. Corpus callosum, hippocampus, and cerebellum exhibited the sharpest reactive astrocytosis, followed by basal ganglia, pons, and medulla oblongata, whereas in cerebral cortex it was considerably less. Astrocyte activation, which failed to correlate with viral antigen presence in neurons, seems to result from a generalized condition, possibly including diffusible brain factors triggered by viral infection. Such widespread astroglial reaction may thus contribute to the outcome of the late neurologic syndrome.

[Treatment of neurological forms of Argentinian hemorrhagic fever with cytarabine]. / Traitement des formes nerveuses de la fièvre hémorragique argentine par la cytarabine.

The effects of cytarabine on neurological forms of Argentina Hemorrhagic Fever were evaluated in 125 patients. The mortality was 12.88 per cent compared to 61.40 per cent in untreated patients. (p less than 0.0001). The efficiency of this treatment depends on its early application. No side effect was observed.

Virus-specific factors in experimental Argentine hemorrhagic fever in rhesus macaques.

A nonhuman primate model for Argentine hemorrhagic fever has been developed that closely mimics the human clinical syndrome. Parenteral infection of adult Macaca mulatta with low-passage isolates of two Junin viral strains resulted in distinctive hemorrhagic or neurological disease in rhesus macaques that correlated with clinical illness patterns present in the humans from whom the viral strains were obtained. Transient leukopenia, together with thrombocytopenia and secondary bacterial septicemia, were documented among animals infected with both viral strains. In contrast, differing patterns of viremia, oropharyngeal viral shedding, and antibody response occurred in the two virus-infected groups. These results, together with postmortem virologic and histopathologic findings, suggest that viral-strain-specific factors are important determinants of clinical disease patterns in this model system.

Protection of Junín virus-infected marmosets by passive administration of immune serum: association with late neurologic signs.

Argentine hemorrhagic fever (Junín virus) is a human viral disease for which immune therapy proves effective, though a late neurologic syndrome is occasionally associated with the treatment. We attempted to determine in the infected marmoset Callithrix jacchus whether immune therapy leads to protection and/or CNS damage. Fifteen C jacchus were inoculated with 10(3) tissue culture infectious dose 50% (TCID50) of the XJ strain of Junín virus. On day 6 post infection (pi), 12 primates were treated with homologous immune serum. Animals were observed daily; and hematologic, serologic, virologic, and histologic studies were performed. All primates, both treated and controls, presented leukopenia, thrombocytopenia, anemia, and weight loss from day 14 pi onward. The three control animals died on days 22, 25, and 32 pi. Among the 12 treated monkeys, 3 died on days 21, 22, and 29. Hematologic values returned to normal during the second month; initial weight was recovered by the fourth month. Three out of the nine survivors showed neurologic alterations of various degrees, with hind-limb paralysis in the most severe case. Among treated monkeys, viremia and viral titers in the lungs, kidney, and lymph nodes were lower than in controls. Neutralizing antibodies were present in high titers in all treated marmosets, except in the one presenting paralysis in which values were minimal and viral persistence was detected in CNS. In conclusion, immune serum treatment of Junín virus-infected marmosets was found to reduce mortality from 100% to 25%. Viremia and viral titers in organs were lowered, and late neurologic signs appeared in 30% of treated survivors.

Treatment of junin virus-infected guinea pigs with immune serum: development of late neurological disease.

Guinea pigs infected with Argentine hemorrhagic fever virus (Junin) were treated with pooled, homologous convalescent sera. Use of 15,000 or 5,000 therapeutic units of immune sera prevented all signs of illness when administered within 24 hr of infection. We could also prevent illness and death in infected guinea pigs as late as 6 days after infection if we used more antisera (30,000 therapeutic units/kg). In some treatment groups, surviving animals developed a late neurological syndrome with prominent rear-limb paralysis. Treated animals typically expressed higher viral titers in the brain than in any other organ. There appeared to be no acute exacerbation of disease by antibody administration. Our data suggest that, after replicating peripherally, Junin virus infects the brain where circulating immunoglobulins may not eliminate viable virus. Subsequent replication of virus in the brain may generate a neurological phase of the illness. Histological examination of brains from guinea pigs in treatment groups favoring the neurological phase of illness showed encephalitis, meningitis, and swollen astrocytes, suggestive of neuronal degeneration. There is likely a delicate balance among presence of virus in the brain, the amount of antibody transported into the central nervous system, and the occurrence of this late neurological aspect of experimental Argentine hemorrhagic fever. Further study of this model may elucidate factors relevant in understanding the continuing problem of the late neurological syndrome seen in some human cases of Argentine hemorrhagic fever treated with immune plasma.

Antibody to mouse alpha/beta interferon abrogates Pichinde virus-induced liver lesions in suckling mice.

Infection of newborn C3HeB/FeJ mice with the arenavirus Pichinde resulted in stunted growth, severe liver cell degeneration, and death. Administration of sheep anti-mouse alpha/beta interferon globulin completely abrogated liver lesions in virus-infected mice, although it did not decrease the incidence of mortality. These results indicate that endogenous interferon may be responsible for some manifestations of viral disease.

Chronic neurologic disease in Junín virus-infected rats.

The purpose of this study was to determine whether Junín virus persistence in CNS of rats was capable of inducing late neurologic disease. Following intracerebral inoculation of newborn animals with XJ strain, three distinct stages could be discerned: an early phase of acute disease, up to 30 days pi, with 5% mortality; an intermediate one, extending to 280 days pi, without clinical signs but with evident viral persistence; and a final period of chronic illness, featuring clinical neurologic syndrome, severe perivascular inflammatory reaction, PAP-labeled viral antigen in a few cerebral and cerebellar neurons, and virus recovery only by coculture. Late neurologic disease seems associated to the lack of effective clearance of brain virus, leading to viral persistence and long lasting immunologic stimulation. The importance of animal models for pathogenic studies on CNS persistent viral infections leading to late neurologic disease is stressed.