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2007 VHF Policy
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Rural African Risk (RAR) Assessment Form
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VHF Risk Assessment Form
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VHF Detailed Action Plan
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UCLH Integrated Care Pathway for VHF
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Viral Haemorrhagic Fever

Page updated 30 April 2007

Viral Haemorrhagic Fever

Key Points

A Rural African Risk Assessment is performed on all new patients with fever from areas endemic for VHF (mainly sub-Saharan Africa)

Then a VHF Risk Assessment must be done

The aim of this policy is to minimise the risk of exposure of healthcare workers and other patients to Viral Haemorrahgic Fever

Introduction

Haemorrhagic diseases that are theoretically capable of being transmitted from man to man include Lassa, Marburg, Ebola and Congo-Crimean haemorrhagic fever. In Africa, transmission of VHF has been associated with the reuse of unsterilised needles and the provision of patient care, without appropriate barrier precautions to prevent exposure to virus-containing blood and other body fluids, such as vomitus, urine and stool. The risks associated with specific body fluids have not been defined, as most health-care workers who caught VHF had had multiple contacts with multiple fluids. Airborne transmission is thought unlikely but is considered a possibility in rare instances from patients in advanced stages of the disease. However, VHF may be transmitted by the airborne route in non-human primates. The risk to contacts is greatest from people who are bleeding, vomiting, have diarrhoea and have shock.

The increasing volume of international travel for vacation, travel by voluntary service organisations, aid workers and UN personnel to areas of conflict particularly to rural areas of Africa, increases the opportunity for the importation of these infections. Recently there were 5 cases of VHF in mainland Europe, one in the UK and 4 in Europe. All have died, despite three having received intensive care.

 

Individual Viruses

Lassa Fever

Lassa fever has been recognised since 1969 and is normally transmitted to man by urine from an infected multimammate rat entering through the skin or mucous membranes. These rats inhabit certain well-defined areas in West Africa. In Africa, clinically identified cases show a high mortality but subclinical and mild undetected infections are more common. Lassa fever may respond to an antiviral drug ribavirin.

There were 9 known cases of Lassa fever imported into the UK between 1974 and 1984, and the last documented case was admitted through UCLH in 2000.

In 1989, a case arrived in Chicago from Nigeria and there have been two cases imported into Tokyo since. A young female student visited Côte d'Ivoire and Ghana in late 1999 and returned to Germany in January 2000 with Lassa Fever.

 

Marburg Disease

Marburg disease was described in 1967 following a European outbreak in which virus was transmitted to technicians from African Green Monkeys caught in Uganda, during laboratory handling of the monkeys and tissue cultures. Subsequently man-to-man transmission occurred. The definitive host is not known and several animal reservoirs have been proposed. There is no treatment.

 

Ebola Virus

Ebola is separate virus in the same family as Marburg virus but outbreaks of both diseases in central Africa have yielded no known source or natural reservoir. Bats may be a vector. Major outbreaks have occurred in hospitals in central and southern Africa. In the Gabon, in 1996, an outbreak in the community affecting a hunter, his friend, a traditional healer led to 24 cases with 17 deaths. A doctor involved flew to Johannesburg for treatment and survived, but a nursing sister caring for him caught Ebola fever and died. In the outbreak in northern Uganda (August 2000-January 2001), there were 425 cases with 224 deaths (53%). A number of health care workers including one doctor died. There is no treatment.

 

Congo-Crimean Haemorrhagic Fever

Congo-Crimean haemorrhagic fever arises from a family of similar viruses that are widespread in Africa, Western Asia and in the USSR. Transmission is usually by tick-bite and man-to-man spread has only been shown to result from contact with infected blood. Strains vary in virulence, those from parts of the Middle-East, north India and Pakistan being rather more so than strains from South Africa.

Incubation Periods

Lassa, Marburg and Ebola fevers have incubation periods which may be quite long (>15 days, perhaps as long as 21 days). Congo-Crimean fever has an incubation period of <14 days and is transmitted by tick bite.

Clinical Features

The features of each of these diseases are very similar. Patients will present with a history of fever, malaise, myalgia, anorexia, nausea, headache, sore throat, diarrhoea, petechial rash or bleeding (e.g. from throat, skin, gut). Pharyngitis and chest pain are characteristic early symptoms. Later the disease is characterised by prostration, hypotension, bruising and bleeding from nose and gums, melaena and haematemesis, thrombocytopenia, increasing haematocrit, mild DIC, respiratory distress and rapid rises in hepatic transaminases. CCF, may present as encephalitis.

Without a bleeding diathesis, the syndrome is non-specific and the diagnosis cannot be made clinically. The most important risk factors are travel to and behaviour in an endemic area. Patients who have been upcountry in Sierra Leone and lived in a tent are much more likely to have Lassa fever than those who stayed in hotels in cities. A detailed, accurate travel history is therefore necessary to decide the level of risk of VHF.

Patients with non-specific fever are far more likely to have malaria, typhoid or non-VHF viral illness than VHF. Sensible precautions should be taken with the blood and excreta from all febrile patients from the Tropics and every care should be taken to reduce the risk of aerosols and needlestick accidents from any blood.

Management Notes

The plan of investigation and care of patients; and measures to prevent secondary transmission are based the UK Department of Health Guidelines and guidelines issued by CDC, Atlanta. The risk categories represent a combination of guidelines from the Advisory Committee on Dangerous Pathogens and more recent guidance. These categories are used for deciding on an action plan in A/E and in the tropical medicine unit.

VHF is restricted to relatively well-defined geographical areas. A detailed history of travel and behaviour is essential to rule out exposure. Referral to current geographical information about outbreaks is essential.

References

UK Department of Health Advisory Committee on Dangerous Pathogens. Guidance on the Management and Control of Viral Heamorrhagic Fevers. (the full report can be accessed at http://www.hpa.org.uk/infections/topics_az/VHF/ACDP_VHF_guidance.pdf)

USA Centres for Disease Control and Prevention. Special Pathogens Branch. Viral Heamorrhagic Fevers.