Infectious Diseases Pediatric
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ex book VOLUME Ralph D. Feigin, M.D. Gail J. 'Demmler, M.D. J. S. Abercrombie Professor and Uhairmano Professor, Department of Pediatrics Department of Pediatrics, and Baylor College of Medicine Distinguished Service Professor, Director, Diagnostic Virology Laboratory Baylor College of Medicine Texas Children 's Hospital Physician-in-Chiel; Houston, Texas Texas Children 's Hospital Physician-in-Chiel; Service of Pediatrics, Sheldon L. Kaplan, M.D. Ben Taub General Hospital Professor and Vice-Chairman of Clinical ChieI; Pediatric Service, Affairs, Department ofPediatrics The Methodist Hospital Baylor College of Medicine Houston, Texas Chief, lnfectious Disease Service, Texas Children's Hospital, James D. Cherry M.D., M.Sc. Houston, Texas ., Professor of Pediatrics David Geffen School of Medicine at UCLA Member, Division of lnfectious Diseases Mattel Children 's Hospita! at UCLA Los Angeles, California 'ISAUNDERSI An Imprint of Elsevier Science effect.21 The agent is sensitive to the action or sodium CHAPTER 192D deoxycholate.9 Oropouche Fever FRANCISCO P. PINHEIRO. Epidemiology AMElIA P. A. TRAV ASSOS DA ROSA- GEOGRAPHIC DISTRIBUTION PEDRO FERNANDO DA C. VASCONCELOS Thus far, the only reported cases of Oropouche rever have occurred in Brazil, Panama, Peru, and Trinidad Oropouche rever is an arbovirus infection that causes an (Fig. 192-3). However, most cases have been limited to the acute febrile episode accompanied by headache, myalgia, Brazilian Amazon region, with none reported in other areas artbralgia, and other systemic symptoms. The symptoms of Brazil. usuaIly recur a few days after the end of the first febrile With a few exceptions, alI episodes of Oropouche rever episode, at which time they are generally less severe. Asep- have been in the form of urban epidemics, including those iQ tic meningitis may develop in some patients. Patients make Belém and Manaus, the largest cities in the Braziliaq a full recovery, without any apparent aftereffects, even in Amazon region. The city of Belém, capital of Pará State, wa8 the most serious cases. No fatalities have been confirmed as struck by three major epidemics during a 20-year period. being attributable to, Oropou,che rever. One of the most The city of Santarém and surrounding villages algo were striking ch~acteristics of Oropouche virus (OROV) is its affected' by a major epidemic in 1974 and 1975.19The first ability to produce epidemics in urban population centers, epidemics that occurred outside the State of Pará, those most of which reportedly,have occurred in the Brazilian striking the cities of Manaus and Barcelos in the State of Amazon tegion. Many of these outbreaks have had a major Amazonas3 and the city of Mazagão in what was then the impact on the stricken cities. , Amapá Territory, were reported early in the 1980s.13Mter a The first case of the disease was described in 1.955 in a period of quiescence lasting unti11988, new outbreaks ofthe residentofVega deOropouche, Trinidad, from whose blood disease struck the cities of Porto Franco and Tocantinópolis the agent was isolated.1 The disease was detected again in in the states ofMaranhão and Tocantins, respectively.26The 1961, this time in the city of Belém, Pará State, northern next reported epidemics occurred in 1991, this time in more Brazil, 'where it caused .an epidemic that affected at least distant locations, namely, in the cities of Ariquemes and 11,000 people.15This epidemic was followed by many other Ouro Preto D'Oeste in the State of Rondônia; the epidemic's epidemics, several of an explosive naLure, in urban popula- impact on these cities was so great that it was reported in tion centers throughout the Brazilian states of Pará, Amapá, the national press. In 1994., another outbreak involving at Amazonas, Tocantins, Maranhão, Rondônia, and Acre.6, 10,15, least 6000 people was recorded in Serra Pelada, Pará State.25 19,2f>' 22, 25, 26 Outside Brazil, epidemics of Oropouche rever The last outbreaks were recorded in 1996 and affected at we~e reported in Panama in 1989 (Quiroz, E., and associ- least tive urban centers in the states of Pará, Amazonas, ate~, Panama, unpublished data, 1989) and in the Amazon and Acre.22 Thus, during 1961 to 1996, more than 30 region of Peru in 19924 and in 1994 (Ministry of Health, epidemics of Oropouche rever have been recorded in Brazil. Peru, and U.S. Naval Medical Research Institute Detach- Serologic surveys6, 13,17,20 have estimated that more than me~t [NAMRID], Lima, 1994). 357,000 people have been infected during this period. How- ever, this estimate is actually quite conservative becausethe incidence of this viral disease had not been computed in Etiblogic Agent many major outbreaks (Belém, 1968; Porto Franco and Tocantinópolis, 1988). Accordingly, possibly more than a Oropouche rever is caused by OROV, which belongs to half million people in the Brazilian Amazon region may have the genus Bunyavirus of the family Bunyaviridae.21 The been infected with the Oropouche virus since the beginning vírus has enveloped spherical, particles 90 to 100 nm in of the 1960s. diameter, the capsid has helical symmetry, and the RNA In addition to the aforementioned epidemic areas, count- contains three segments.11,21 Phylogenetic analysis has less small villages scattered throughout virtually the entire revealed that alI OROV, strains forro a monophylogenetic Amazon region have residents who show hemagglutination- group consisting of three distinct lineages. Lineage I con- inhibition antibodies against OROV. In general, the preva- tains the prototype strain from Trinidad and most of the lence of these antibodies is less than 3 percent, with the Brazilian strains, lineage 11 contains six Peruvian strains exception of Ilha de Gurupá, where it is 10.7 percent.2o isolated between 1992 and 1998 and two strains from west- Outside Brazil, outbreaks were reported in Panama and ern! Braz~l isolated in 1991, and lineage 111comprises four Peru. The outbreak in Panama occurred in 1989 in the vil- strJins isolated from Panama during 1989.24Antigenically, lage of Bejuco, which is located approximately 50 km west of it belongs to the Simbu group, which in turn. is part of the the capital (Quiroz, E., and associates, Panama, unpublished Bunyamwera supergroup of arboviruses. The vírus has a data, 1989). The first epidemic in Peru was reported in 1992 hemagglutinin that' is active against geese erythrocytes, and in the city of Iquitos in the Peruvian Amazon region4; sub- it can be recovered from infected hamster serum treated sequently, an outbreak occurred in Puerto Maldonado, with acetone (Travassos da Rosa, Belém, unpublished data, Madre de Dios, algo in the Peruvian Amazon region 1969). lntracerebral and intraperitoneal inoculation of (Ministry ofHealth, Peru, and NAMRID, Lima, 1994). Stud- OROV into .baby mice and intracerebral, intraperitoneal, ies performed in Peru suggest that transmission of OROV and subcutaneous inoculation of the vírus into adult ham- occurs continuously in the population of the city of Iquitos sters produce lethal infections. The vírus replicates in and surrounding villages.27Evidence of immunity to OROV numerous cell cultures, including Vero, BHK-21, and pri- was detected in nonhuman primates in Colombia, thus sug- mary chicken embryo fibroblast, and causes a cytopathic gesting its presence in that country as well.9 2418 CHAPTER192 Other Bunyaviruses ~~~ <\lJ V~ FIGURE 192-3 ...Outbreaks of Oropouche fevur rep(lrlud in lhe Americas fro!l1 196.1 to 2000. '"2419~ 2420 SECTION XVII Virallnfections lNCIDENCE TRANSMISSION MECHANISM A significant characteristic of Oropouche rever has been the Laboratory studies and broad-based surveys conducted ~xceptionally high attack rates seen during several out- by the Evandro Chagas Institute during the course of breaks'. A.lthough incidence rates have varied in different epidemics point to the importance of lhe insect C. paraensis outbreliks, a rate of 30 percent was quite common. The pro- in the Ceratopogonidae family as the urban vector for portion of those infected who ~uffer overt disease is not OROV.14.18 These tiny insects, commonly known as maru- known with certainty, but in one epidemic, clinical disease ins (biting midges) in the Amazon region, are active during developed in 63percent ~f lhose i,nfcctcd." , the day, particularly in lhe late afternoon hours. They crave Gender-speçific attack rates vary, with rates in females human blo'od and bite people inside as well as outside their slightly higher than those in males in villages in the Bra- homes.8. 19.23 The disease is transmitted by inoculation of gantina area; eastern Pará State; struck by the virus in the virus into exposed individuaIs by bites of infected 1979,6with the opposite being true in the outbreak in Be.lém midges. that garoe year. Howcvcr', in thc rcporLed cpidcrnics in San- tarém, the infection struck females twice as oftenas males.5 Oropo~che rever affects alI age groups, although in certain CYCLES outbreaks its incidence was higher in children and young adultsL ' Studies conducted by the Evandro Chagas Institute2O suggest that OROV is perpetuated in nature through two different cycles, namely, an urban cycle and a wild DIFFUSION OF EPIDEMICS cycle. In the urban or epidemic cycle, the virus is transmitted As indicated earlier, Oropouche rever epidemics have from person to person by the bite of C. paraensis. One ofthe struck different Iocations at varying intervals. However, most conclusive pieces of evidence attesting to this assertion many ! outbreaks were marked by bona fide epidemic lies in demonstration of the ability of C. paraensis, after sweep$, with countIess numbers of viII ages within a partic- feeding on the blood of viremic patients, to transmit the ular geographic area being affected by the virus. This virus to hamsters bitten by the midges 5 or more days difTusion phenomenon was observed in Bragança in 1967, later.18 Moreover, these midges typically are found in high in Santarém in 1974 and 1975, and even more so in Belém densities during periods of epidemics.