Joseph B. McCormick

Lassa fever: Effective therapy with ribavirin

Abstract In a study of Lassa fever in Sierra Leone, West Africa, we identified two variables associated with a high risk of death, and we evaluated the efficacy of ribavirin and Lassa virus-convalescent plasma for the treatment of Lassa fever. A serum aspartate aminotransferase level greater than or equal to 150 IU per liter at the time of hospital admission was associated with a case-fatality rate of 55 percent (33 of 60). Patients with the same risk factor who were treated for 10 days with intravenous ribavirin, begun within the first 6 days after the onset of fever, had a case-fatality rate of 5 percent (1 of 20) (P = 0.0002 by Fishers exact test). Patients whose treatment began seven or more days after the onset of fever had a case-fatality rate of 26 percent (11 of 43) (P = 0.01). Viremia with levels greater than or equal to 10(3.6) TCID50 per milliliter on admission was associated with a case-fatality rate of 76 percent (35 of 46). Patients with this risk factor who were treated with intravenous ribavirin within the first six days after onset of fever had a case-fatality rate of 9 percent (1 of 11) (P = 0.006), whereas those treated after seven days or more of illness had a fatality rate of 47 percent (9 of 19) (P = 0.035). Oral ribavirin was also effective in patients at high risk of death. Lassa-convalescent plasma did not significantly reduce mortality in any of the high-risk groups. We conclude that ribavirin is effective in the treatment of Lassa fever and that it should be used at any point in the illness, as well as for postexposure prophylaxis.

Defective humoral responses and extensive intravascular apoptosis are associated with fatal outcome in Ebola virus-infected patients.

Ebola virus is very pathogenic in humans. It induces an acute hemorrhagic fever that leads to death in about 70% of patients. We compared the immune responses of patients who died from Ebola virus disease with those who survived during two large outbreaks in 1996 in Gabon. In survivors, early and increasing levels of IgG, directed mainly against the nucleoprotein and the 40-kDa viral protein, were followed by clearance of circulating viral antigen and activation of cytotoxic T cells, which was indicated by the upregulation of FasL, perforin, CD28 and gamma interferon mRNA in peripheral blood mononuclear cells. In contrast, fatal infection was characterized by impaired humoral responses, with absent specific IgG and barely detectable IgM. Early activation of T cells, indicated by mRNA patterns in peripheral blood mononuclear cells and considerable release of gamma interferon in plasma, was followed in the days preceding death by the disappearance of T cell-related mRNA (including CD3 and CD8). DNA fragmentation in blood leukocytes and release of 41/7 nuclear matrix protein in plasma indicated that massive intravascular apoptosis proceeded relentlessly during the last 5 days of life. Thus, events very early in Ebola virus infection determine the control of viral replication and recovery or catastrophic illness and death.

ACQUIRED IMMUNODEFICIENCY SYNDROME IN A HETEROSEXUAL POPULATION IN ZAIRE

38 patients with the acquired immunodeficiency syndrome (AIDS) were identified in Kinshasa, Zaire, during a 3 week period in 1983. The male to female ratio was 1.1:1. The annual case rate for Kinshasa was estimated to be at least 17 per 100 000. Opportunistic infections were diagnosed in 32 (84%) patients, disseminated Kaposis sarcoma (KS) with opportunistic infection in 5 (13%), and disseminated KS alone in 1 patient. Immunological characteristics of these patients were as reported for cases in the USA and Europe, but immunological abnormalities were also found in 6 controls with infectious diseases but no symptoms of AIDS. Female AIDS cases were younger than male patients with AIDS (mean ages 28.4 vs 41.1 years, respectively), and were more often single (14/18 vs 2/20). Homosexuality, intravenous drug abuse, and blood transfusion did not appear to be risk factors in these patients. The findings of this study strongly argue that the situation in central Africa represents a new epidemiological setting for this worldwide disease--that of significant transmission in a large heterosexual population. Two instances of clusters of AIDS (not included in the above series) involving males and females with frequent heterosexual contact further implicate heterosexual transmission.

Human asymptomatic Ebola infection and strong inflammatory response

BACKGROUND Ebola virus is one of the most virulent pathogens, killing a very high proportion of patients within 5-7 days. Two outbreaks of fulminating haemorrhagic fever occurred in northern Gabon in 1996, with a 70% case-fatality rate. During both outbreaks we identified some individuals in direct contact with sick patients who never developed symptoms. We aimed to determine whether these individuals were indeed infected with Ebola virus, and how they maintained asymptomatic status. METHODS Blood was collected from 24 close contacts of symptomatic patients. These asymptomatic individuals were sampled 2, 3, or 4 times during a 1-month period after the first exposure to symptomatic patients. Serum samples were analysed for the presence of Ebola antigens, virus-specific IgM and IgG (by ELISA and western blot), and different cytokines and chemokines. RNA was extracted from peripheral blood mononuclear cells, and reverse transcriptase-PCR assays were done to amplify RNA of Ebola virus. PCR products were then sequenced. FINDINGS 11 of 24 asymptomatic individuals developed both IgM and IgG responses to Ebola antigens, indicating viral infection. Western-blot analysis showed that IgG responses were directed to nucleoprotein and viral protein of 40 kDa. The glycoprotein and viral protein of 24 kDa genes showed no nucleotide differences between symptomatic and asymptomatic individuals. Asymptomatic individuals had a strong inflammatory response characterised by high circulating concentrations of cytokines and chemokines. INTERPRETATION This study showed that asymptomatic, replicative Ebola infection can and does occur in human beings. The lack of genetic differences between symptomatic and asymptomatic individuals suggest that asymptomatic Ebola infection did not result from viral mutations. Elucidation of the factors related to the genesis of the strong inflammatory response occurring early during the infectious process in these asymptomatic individuals could increase our understanding of the disease.

Crimean Congo-Haemorrhagic Fever treated with oral ribavirin

Crimean-Congo Haemorrhagic Fever (CCHF) is an often-lethal haemorrhagic fever caused by a tick-borne virus. There are no published data on ribavirin treatment of CCHF-infected patients, despite established in-vitro and in-vivo sensitivity. We report three health workers--two surgeons and a hospital worker--infected with CCHF virus in Pakistan who were treated with oral ribavirin 4 g/day for four days, then 2.4 g/day for six days. Intravenous ribavirin was unavailable. All three patients were severely ill with low platelet and white-cell counts, raised aspartate transaminase and evidence of impaired haemostasis. Based on published reports, all had an estimated probability of death of 90% or more. The patients became afebrile, and their haematological and biochemical abnormalities returned to normal within 48 h of ribavirin treatment; all made a complete recovery, and developed IgG and IgM antibody to CCHF virus. Our experience with ribavirin treatment is encouraging, but does not constitute evidence of efficacy. Given the difficulties in gathering adequate treatment data, we propose a consensus protocol for both intravenous and oral treatment of CCHF. This protocol could be distributed to key medical personnel in areas endemic for CCHF and used to provide a firm basis for effective treatment recommendations.

Review of cases of nosocomial Lassa fever in Nigeria : the high price of poor medical practice

Abstract Objective: To investigate two hospital outbreaks of Lassa fever in southern central Nigeria. Setting: Hospitals and clinics in urban and rural areas of Imo State, Nigeria. Design: Medical records were reviewed in hospitals and clinics in both areas. Patients with presumed and laboratory confirmed Lassa fever were identified and contracts traced. Hospital staff, patients, and local residents were questioned, records were carefully reviewed, and serum samples were taken. Serum samples were assayed for antibody specific to Lassa virus, and isolates of Lassa virus were obtained. Results: Among 34 patients with Lassa fever, including 20 patients, six nurses, two surgeons, one physician, and the son of a patient, there were 22 deaths (65% fatality rate). Eleven cases were laboratory confirmed, five by isolation of virus. Most patients had been exposed in hospitals (attack rate in patients in one hospital 55%). Both outbreak hospitals were inadequately equipped and staffed, with poor medical practice. Compelling, indirect evidence revealed that parenteral drug rounds with sharing of syringes, conducted by minimally educated and supervised staff, fuelled the epidemic among patients. Staff were subsequently infected during emergency surgery and while caring for nosocomially infected patients. Conclusion: This outbreak illustrates the high price exacted by the practice of modern medicine, particularly use of parenteral injections and surgery, without due attention to good medical practice. High priority must be given to education of medical staff in developing countries and to guidelines for safe operation of clinics and hospitals. Failure to do so will have far reaching, costly, and ultimately devastating consequences.

Unsafe injections and the transmission of hepatitis B and C in a periurban community in Pakistan

Following reports of frequent deaths associated with jaundice and chronic liver disease among adults in a periurban community of Karachi, Pakistan, an investigation was conducted to evaluate the relationship between injections and viral hepatitis infections, to identify the reasons why patients received frequent injections, and to observe the injection practices employed in clinics. Two hundred and three adult patients were interviewed as they left each of the 18 area clinics. Practitioners were interviewed and three consecutive injections were observed at each clinic. Eighty-one per cent of patients received an injection on the day of the interview. Of the 135 patients who provided a serum sample, 59 (44%) had antibodies against hepatitis C virus and 26 (19%) had antibodies against hepatitis B virus. Patients who received more injections were more likely to be infected with hepatitis C. If oral and injected medications were equally effective, 44% of patients preferred injected medication. None of the practitioners knew that hepatitis C could be transmitted by injections. Non-sterile syringes and needles that had been used earlier in the day on other patients were used for 94% of the observed injections. Interventions to limit injections to those which are safe and clinically indicated are needed to prevent injection-associated infections in Pakistan and other low-income countries.

Descriptive analysis of Ebola virus proteins.

The virion proteins of two strains of Ebola virus were compared by SDS-polyacrylamide gel electrophoresis (PAGE) and radioimmunoprecipitation (RIP). Seven virion proteins were described; an L (180K), GP (125K), NP (104K), VP40 (40K), VP35 (35K), VP30 (30K), and VP24 (24K). The RNP complex of the virus contained the L, the NP, and VP30, with VP35 in loose association with them. The GP was the major spike protein, with VP40 and VP24 making up the remaining protein content of the multilayered envelope.

Diagnosis of Ebola haemorrhagic fever by RT-PCR in an epidemic setting.

This study reports the first field evaluation of a new diagnostic technique for Ebola virus disease with sensitivity and specificity. Ebola virus causes rare but fulminating outbreaks in Equatorial Africa. Rapid differentiation from other infections is critical for timely implementation of public health measures. Patients usually die before developing antibodies, necessitating rapid virus detection. A reverse transcriptase‐polymerase chain reaction (RT‐PCR) assay was developed, implemented and evaluated at Centre International de Recherches Médicales de Franceville (CIRMF) in Gabon, to detect Ebola viral RNA in peripheral blood mononuclear cells (PBMC). Twenty‐six laboratory‐confirmed patients during and 5 after the acute phase of Ebola haemorrhagic fever, 15 healthy controls and 20 febrile patients not infected with Ebola virus were studied. RT‐PCR results were compared with ELISA antigen capture, and Ebola specific IgM and IgG antibody detection. Ebola virus RNA was amplified from 26/26 specimens from the acute phase, 3/5 during recovery, 0/20 febrile patients and 1/15 negative controls. Sensitivity of RT‐PCR in identifying acute infection and early convalescence compared with antigen or IgM detection was 100% and 91% respectively, and specificity compared with antigen detection and IgM assay combined was 97%. Antigen capture detected only 83% of those identified by PCR, and IgM only 67%. Ebola virus RNA was detected in all 13 fatalities, only 5 of whom had IgM and none IgG. RT‐PCR detected Ebola RNA in PBMC one to three weeks after disappearance of symptoms when antigen was undetectable. RT‐PCR was the most sensitive method and able to detect virus from early acute disease throughout early recovery. J. Med. Virol. 60:463–467, 2000.

Use of pertussis vaccine in an epidemic involving hospital staff.

An epidemic of pertussis occurred among hospital staff caring for paediatric patients. Eight physicians and five nurses were affected. Pertussis developed in six newborn infants exposed to infected hospital staff in the nursery. Erythromycin prophylaxis was used to control the epidemic. Clinical pertussis developed in five adults infected with Bordetella pertussis before erythromycin was used, whereas symptoms developed in only one of the eight adults who became infected after erythromycin prophylaxis was started. Pertussis vaccine was given to adult volunteers in the hospital, and in 77% of two hundred and eighty-six vaccinees there was a fourfold rise in pertussis agglutinins. Local reactions were common, and in two vaccinees generalised rashes developed. One of these required treatment with corticosteroids. The risk of pertussis occurring in adults providing medical care for children should be recognised, and employees with symptoms should be removed from the hospital environment.