Alkhurma Hemorrhagic Fever

Chapter 5

Alkhurma Hemorrhagic Fever Pierre E. Rollin1 and Ziad A. Memish2 1

Viral Special Pathogens Branch, Centers for Disease Control and Prevention, Atlanta, GA, USA, 2Global Center for Mass Gathering Medicine, Ministry of Health, Riyadh, Kingdom of Saudi Arabia

CASE PRESENTATION A 32-year-old male Egyptian butcher working in Saudi Arabia was presented to hospital with fever, generalized body aches, and vomiting of 5 day duration. He then developed irritability, convulsions with hematemesis, and melena. On examination the patient was unconscious and in bad general condition. His neck was lax, with no sign of meningeal irritation. His temperature was 38.5 C, blood pressure 90 160 mmHg, and pulse rate 112/min and regular. Abdominal examination showed no abnormality. Skin examination showed ecchymotic patches at injection sites. Laboratory examination revealed the following: leucopenia (leucocytes 2.9 3 109/L), thrombocytopenia (platelets 38 3 109/L), and elevated levels of liver enzymes (serum glutamic oxalacetic transaminase (AST) 680 units/L, serum glutamic pyruvic transaminase (ALT) 1950 units/L), creatinine phosphokinase (18,200 units/L), and blood urea (186 mmol/L). The patient received intensive supportive treatment; however, he became deeply comatose and died of irreversible shock with renal and respiratory failure 2 days after admission. The diagnosis was confirmed by virus isolation from a blood sample taken 6 days after the onset of symptoms. This is a published case report.1

1. WHY THIS CASE WAS SIGNIFICANTLY IMPORTANT AS AN EMERGING INFECTION Alkhurma hemorrhagic fever (AHF) is a viral infection recently described in Saudi Arabia, associated in severe forms with severe hemorrhagic and neurologic manifestations. Mortality in hospitalized patients varied between 1 and 20%. The recent laboratory confirmation of the disease in tourists visiting

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Egypt extends the geographical range of the virus and suggests that infections due to AHF virus, a tick-borne flavivirus, are underreported. The persistence of the virus within the tick population (vertical and horizontal transmission such as co-feeding) and the role of livestock infection in the transmission of the virus to humans are unknown. Their understanding will have great implications on public health, prophylaxis, and health education measures.

2. WHAT IS THE CAUSATIVE AGENT? Alkhurma hemorrhagic fever virus (AHFV) was first isolated from specimens collected from a patient in Mecca, Saudi Arabia, in 1995.1 The patient (a butcher) presented a rapid, fatal hemorrhagic fever and Crimean-Congo hemorrhagic fever was clinically suspected. AHFV is a variant of Kyasanur Forest disease virus (KFDV), which is endemic in the Karnataka State in India and a member of the tick-borne encephalitis group (family Flaviviridae, genus Flavivirus, enveloped, segmented, negative-strand RNA virus).2,3 Phylogenetic analysis of full-genome sequences of AHFV and KFDV revealed a low diversity and a slow rate of molecular evolution, similar to other tick-borne flaviviruses.3,4 The suggested divergence between AHFV and KFDV, around 770 years ago, argues against a recent introduction of KFDV in Saudi Arabia. The virus is classified as a BSL-3 or BSL-4 agent and its manipulation required high-containment laboratories and trained personnel.

3. WHAT IS THE FREQUENCY OF THE DISEASE? Since the first description in the Mecca region, several hundred human cases have been reported in other western Governorates of Saudi Arabia: Jeddah, Jizan, and Najran (Figure 5.1). Antibodies have been found in people living in other Governorates of Saudi Arabia, and in United Arab Emirates.5, unpublished data Three human cases have also been reported in tourists visiting a camel market in Al-Shalateen, along the Red Sea in southern Egypt.6,7 Because of the large geographic range of the tick vector, it is expected that the distribution of the virus is more extensive, with probable unsuspected human cases in Yemen and Sudan. The monthly distribution of human cases, with a peak in spring and summer, is certainly related to the ecology of the reservoirs. In the early description of the disease, the case fatality was reaching 25%. Further studies in Najran added subclinical infection to the spectrum of the disease, lowering the case fatality rate to 1 2%.1,8,9

4. HOW IS THE VIRUS TRANSMITTED? Epidemiological, veterinary and entomological aspects, and the cycle of transmission of AHFV are still poorly understood. AHFV is a zoonotic

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FIGURE 5.1 Geographic range of Alkhurma virus (the large black dots correspond to the region on known endemicity of the virus).

virus, and has been detected and isolated from adult soft ticks (Ornithodoros savignyi) and hard ticks (Hyalomma dromedari) collected in western Saudi Arabia.10,11 Both ticks have a very wide distribution. People can be infected through tick bite or when crushing infected ticks. Soft ticks feed and stay attached to the host only for a short period of time and this could be a reason for them being unnoticed by patients. All the epidemiological studies identified contacts with domestic animals or livestock as risk factors for human infections. There is no known disease in animals after infection by AHFV, but no experimental infections have been done, and as with Crimean-Congo hemorrhagic fever virus, another tick-borne virus, the animal could develop a viremia without obvious clinical symptoms. If this is the case, slaughtering animals during this phase of infection could certainly be the source of human infection. Mosquito transmission has been hypothesized but no detection or isolation in wild-caught mosquitoes has been reported and the taxonomic classification of the virus makes it unlikely. No transmission through non-pasteurized milk consumption has been described, although other viruses from the tick-borne encephalitis group have been transmitted to humans through this route. No nosocomial transmissions are reported in healthcare workers but standard precautions are recommended when handling AHFV patients or their biological specimens.

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5. WHICH FACTORS ARE INVOLVED IN DISEASE PATHOGENESIS? WHAT ARE THE PATHOGENIC MECHANISMS? Very little is known about the pathogenesis of AHFV in humans and no animal models of the human disease are available. The virus is present in the blood during the clinical phase of the disease, then disappears and is replaced by IgM and IgG antibodies. AHFV certainly affect the liver, as reflected by the elevation of the liver enzymes, and this tropism may be partly associated with hemostasis abnormalities and bleeding tendencies in patients. Although the central nervous system is affected in a certain number of patients, no cerebrospinal fluid (CSF) examination or imaging evaluation of the brain has been reported. The neurotropism during human infection by members of the tick-borne flavivirus group is well known: KFDV can be isolated from the CSF12 and intrathecal production of antibodies is also described in tick-borne encephalitis.13

6. WHAT ARE THE CLINICAL MANIFESTATIONS? It is difficult to have a definite duration for the incubation of AHF, because of the permanent exposure to the potential risk factors, but in the Italyimported patients, the incubation after apparent tick bite was as short as 2 to 4 days, comparable with the reported 2 7 days for KFD. The disease appears to be diphasic at least in some patients, and starts as a non-specific flu-like syndrome with fever, anorexia, malaise, diarrhea, vomiting, followed by either neurological or hemorrhagic manifestations in the severe forms (Table 5.1).1,6 9,14 16 Laboratory abnormalities such as thrombocytopenia, leukopenia, elevated creatine phosphokinase, LDH, and liver enzymes are nearly always present in hospitalized patients (Table 5.2).1,6 8,14 16 No data are available on CSF even in neurological forms. Multi-organ failures precede the fatal outcome. No sequelae have been reported after clinical recovery. Rhabdomyolysis has been reported in one patient.7 As reported by Alzahrani and colleagues,9 milder clinical forms that do not require hospitalization or even doctor consultation exist.

7. HOW DO YOU DIAGNOSE? In Saudi Arabia, a clinical, laboratory, and epidemiologic case definition has been put in place (Table 5.3). ALK virus infection can be confirmed at the acute phase of the disease by direct detection of virus in blood, plasma, or serum either by virus isolation or by detection of the viral RNA. The same techniques can be used to detect ALK virus from viremic animals or infected ticks. At later stages of human disease, in serological surveys, or in animal samples, IgM and IgG antibodies may be detectable in the blood, plasma,

TABLE 5.1 Alkhurma Hemorrhagic Fever: Clinical Signs and Symptoms Variable

Zaki1 n (%)

Madani14 Memish15 Charrel16 Madani8 Alzahrani9 n (%) n (%) n (%) n (%) hospitalized n (%)

Fever

10 (100) 20 (100)

Headache

4 (24)

1 (100)

78 (100)

10 (100) 15 (75)

16 (100)

67 (85.9)

Malaise

15 (75)

16 (100)

67 (85.9)

Myalgia

15 (75)

16 (100)

64 (82.1)

64 (82.1)

16 (100)

43 (55.1)

43 (55.1)

65 (83.3)

65 (83.3) 56 (71.8)

10 (100) 1 (5)

Arthralgia

9 (45)

Backache, body ache

10 (100) 5 (25)

16 (100)

56 (71.8)

Nausea, vomiting

10 (100) 10 (50)

10 (62.5)

56 (71.8)

5 (20)

4 (25)

40 (51.3)

3 (15)

2 (12.5)

0

Diarrhea Rash

2 (20)

11 (100)

Carletti6 Madani8 Ravanini7 n (%) n (%) n (%)

16 (100)

Retro-orbital pain

1 (100)

Alzahrani9 nonhospitalized n (%)

78 (100)

1 (100)

67 (85.9) 1 (100) 1 (100)

1 (100)

67 (85.9)

56 (71.8) 40 (51.3) 1 (100)

5 (46)

2 (12)

0 (Continued )

TABLE 5.1 (Continued) Variable

Zaki1 n (%)

Madani14 Memish15 Charrel16 Madani8 Alzahrani9 n (%) n (%) n (%) n (%) hospitalized n (%)

Alzahrani9 nonhospitalized n (%)

Bleeding ( )

2 (20)

11 (55)

1 (100)

0

1 (5)

1 (100)

Confusion, disorientation

4 (25)

20 (25.6) 5 (46) 8 (10.7)

Carletti6 Madani8 Ravanini7 n (%) n (%) n (%) 20 (25.6) 8 (10.7)

Neck stiffness

7 (9.3)

3 (27)

0

7 (9.3)

Seizures

4 (5.1)

2 (18)

0

4 (5.1)

Encephalitis

1 (10)

4 (20)

Mortality

2 (20)

5 (25)



0

5 (31)

10 (12.8)

10 (12.8)

1 (1.3)

1 (1.3)

May include epistaxis, gum bleeding, melena, hematemesis, and genital bleeding.

TABLE 5.2 Alkhurma Hemorrhagic Fever: Laboratory Data Variable

Zaki1 n (%)

Madani14 n (%)

Memish15 n (%)

Charrel16 n (%)

Carletti6 n (%)

Madani8 n (%)

Ravanini7 n (%)

Leukopenia

10 (100)

13 (65)

1 (100)

16 (100)

1 (100)

57/65 (87.7)

1 (100)

Thrombocytopenia

10 (100)

15 (75)

1 (100)

16 (100)

1 (100)

30/65 (46.2)

1 (100)

High bilirubin

6 (30)

5/39 (12.8)

High hemoglobin

1 (5)

5/62 (8.1)

High INR

9 (45)

5/21 (23.8)

1 (100)

High PTT

15 (75)

10/19 (52.6)

1 (100)

21/46 (41.7)

1 (100)

9/36 (25)

1 (100)

High CPK

10 (100)

High LDH

19 (5)

1 (100)

17 (85)

1 (100)

16 (100)

High AST

10 (100)

20 (100)

1 (100)

16 (100)

1 (100)

54/63 (85.7)

1 (100)

High ALT

10 (100)

16 (80)

1 (100)

16 (100)

1 (100)

43/64 (67.2)

1 (100)

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TABLE 5.3 Alkhurma Hemorrhagic Fever: Saudi Arabia Case Definition17 Clinical case definition (human cases): Suspected: Case meets the clinical and exposure criteria Probable: suspected case with clinical laboratory data (e.g., thrombocytopenia, leucopenia, elevation of liver enzymes, elevated CPK or LDH) and IgM detected by capture ELISA Confirmed: Probable case and laboratory criteria listed below Clinical criteria: Unexplained acute febrile illness (fever. 38 C) with one of the three following features: Hemorrhagic manifestations not related to injury (bleeding under the skin, in internal organs or from body orifices; and positive tourniquet test) Liver involvement (jaundice, hepatomegaly) Neurological involvement (severe headache, altered mental status, and/or seizures) Laboratory criteria (one or more of the following laboratory findings): AHFV RNA detected by real-time or conventional RT-PCR Virus isolation/identification using cell culture or suckling mice Four-fold antibody (IgM and or IgG) rise in paired serum samples using ELISA or IFA Neutralization test—preferably plaque reduction for paired sera Exposure criteria (one or more of the following exposures before onset of symptoms): Recent contact with animal, blood, or other animal products Recent exposure to or bite by tick Contact with blood or body fluid from a confirmed human case Work in a laboratory that handles AHFV specimens/isolates

and serum by ELISA.18 Viral antigen can certainly be detected by immunohistochemistry in formalin-fixed tissues and paraffin-embedded blocks. As usual, when an infectious disease etiology is suspected, a combination of several techniques should be used for laboratory confirmation.

7.1 Viral Isolation All isolation attempts require high-containment laboratory and trained personnel. Virus can be isolated from acute patient samples using several cell types, but most often Vero or BHK21 cells; a cytopathic effect is easily seen after 9 10 days. If newborn suckling mice are available, the animals, after intracerebral inoculation, show paralysis and die after 5 7 days.1,4

7.2 Molecular Detection: RT-PCR Conventional and real-time reverse transcriptase polymerase chain reactions (RT-PCR) are available for detecting ALK RNA from acute human

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samples (first week post-onset), or from infected ticks. A real-time kit is commercially available (TIB MolBiol LightMixs Kit Alkhurma Virus, Cat. No. 40-0581-16). The virus being present in circulating macrophages, using blood or buffy-coat will increase the sensitivity of the molecular detection.19

7.3 Serological Diagnosis The interpretation of the serological assays needs caution when several flaviviruses are circulating in the same geographical zone. Several IgM and IgG ELISAs have been developed and are used in Saudi Arabian laboratories for identification of acute human cases or surveys.5,9

8. HOW DO YOU DIFFERENTIATE THIS DISEASE FROM SIMILAR ENTITIES? Clinical diagnosis is difficult or impossible without etiologic laboratory confirmation. Crimean-Congo hemorrhagic fever and Rift Valley fever should be suspected in patients fulfilling the clinical criteria of the proposed case definition, coming from the AHFV endemic area, and exposed to identical risk factors (exposition to livestock, working in slaughterhouses). The initial laboratory data (white blood and platelets count, liver function tests) may also be identical. Molecular assays are very specific and sensitive. But the well-known antibody cross-reactivity within flaviviruses (i.e., dengue and maybe Kadam viruses) circulating in the same geographical range make any diagnosis based on a single serological assay suspicious.20,21

9. WHAT IS THE THERAPEUTIC APPROACH? There is no standard specific treatment for ALK disease. Patients receive supportive therapy. This consists of balancing the patient’s fluids and electrolytes, maintaining their oxygen status and blood pressure, and treating them for any complicating infections.

10. WHAT ARE THE PREVENTIVE AND INFECTION CONTROL MEASURES? No treatment or specific prophylaxis being available, prevention and awareness are the only recommended measures. Controlling vectors is difficult and interrupting the cycle of the virus within the reservoirs is impossible. In the endemic region, it is recommended, as for other tick-borne pathogens, if possible to avoid tick-infected areas and limit contact with tick-infested livestock or domestic animals. At the individual level, people should use

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tick repellents on skin and clothes, check skin for attached ticks and remove them as soon as possible, and prevent tick infestation on domestic animals (tick collars) and livestock (dipping). Applications of pesticides and insecticides around the habitations and animal living areas could have some effect in reducing the tick populations. Although difficult in practice, people working with animals or animal products on farms or in slaughterhouses should avoid unprotected contact with blood of potentially viremic animals. No human-to-human or nosocomial infections have been described, but standard infection control practices are recommended for healthcare workers.

REFERENCES 1. Zaki AM. Isolation of a flavivirus related to the tick-borne encephalitis complex from human cases in Saudi Arabia. Trans. Roy Soc Trop Med Hyg 1997;91:179 81. 2. Charrel RN, Zaki AM, Attoui H, et al. Complete coding sequence of the Alkhurma virus, a tick-borne flavivirus causing severe hemorrhagic fever in humans in Saudi Arabia. Biochem Biophys Res Comm 2001;287:455 61. 3. Charrel RN, Zaki AM, Fakeeh M, et al. Low diversity of Alkhurma hemorrhagic fever virus, Saudi Arabia, 1994 1999. Emerg Infect Dis 2005;11:683 8. 4. Dodd KA, Bird BH, Khristova ML, et al. Ancient Ancestry of KFDV and AHFV revealed by complete genome analyses of viruses isolated from ticks and mammalian hosts. PLoS Negl Trop Dis 2011;5:e1352. 5. Memish ZA, Albarrak A, Almazroa MA, et al. Seroprevalence of Alkhurma and other hemorrhagic fever viruses, Saudi Arabia. Emerg Infect Dis 2011;17:2316 8. 6. Carletti F, Castilletti C, Di Caro A, et al. Alkhurma hemorrhagic fever in travelers returning from Egypt, 2010. Emerg Infect Dis 2010;16:1979 82. 7. Ravanini P, Hasu E, Huhtamo E, et al. Rhabdomyolysis and severe muscular weakness in a traveler diagnosed with Alkhurma hemorrhagic fever virus infection. J Clin Virol 2011;52:254 6. 8. Madani TA, Azhar EI, Abuelzein EME, et al. Alkhumra (Alkhurma) virus outbreak in najran, Saudi Arabia: epidemiological, clinical, and laboratory characteristics. J Infect 2011;62:67 76. 9. Alzahrani AG, Al Shaiban HM, Al Mazroa MA, et al. Alkhurma hemorrhagic fever in humans, Najran, Saudi Arabia. Emerg Infect Dis 2010;16:1882 8. 10. Charrel RN, Fagbo S, Moureau G, Alqahtani MH, Temmam S, de Lamballerie X. Alkhurma hemorrhagic fever virus in Ornithodoros savignyi ticks. Emerg Infect Dis 2007;13:153 5. 11. Mahdi M, Erickson BR, Comer JA, et al. Kyasanur Forest disease virus Alkhurma subtype in ticks, Najran Province, Saudi Arabia. Emerg Infect Dis 2011;17:945 7. 12. Bhatt PN, Work TH, Varma VGR, Trapido H, Narasimha Murthy DP, Rodrigues FM. Isolation of Kyasanur forest disease virus from infected humans and monkeys of Shimoga district, Mysore State. Indian J Med Sci 1966;20:316 20. 13. Gunther G, Haglund M, Lindquist L, Skoldenberg B, Forsgren M. Intrathecal IgM, IgA and IgG antibody response in tick-borne encephalitis. Long-term follow-up related to clinical course and outcome. Clin Diag Virol 1997;8:17 29. 14. Madani TA. Alkhumra virus infection, a new viral hemorrhagic fever in Saudi Arabia. J Infect 2005;51:91 7.

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15. Memish ZA, Balkhy HH, Francis C, Cunningham G, Hajeer AH, Almuneef MA. Alkhurma haemorrhagic fever: case report and infection control details. Br J Biomed Sci 2005;62:37 9. 16. Charrel RN, de Lamballerie X, Zaki AM. Human cases of hemorrhagic fever in Saudi Arabia due to a newly discovered flavivirus, Alkhurma hemorrhagic fever virus. In: Lu Y, Essex M, Roberts B, editors. Emerging infections in Asia. New York: Springer; 2008. p. 179 92. 17. Memish ZA, Fagbo SF, Assiri AM, et al. Alkhurma viral hemorrhagic fever virus: proposed guidelines for detection, prevention, and control in Saudi Arabia. PLoS Negl Trop Dis 2012;6:e1604. 18. Memish ZA, Charrel RN, Zaki AM, Fagbo SF. Alkhurma haemorrhagic fever—a viral haemorrhagic disease unique to the Arabian Peninsula. Int J Antimicrob Agents 2010;36 (Suppl. 1):S53 7. 19. Madani TA, Abuelzein EE, Azhar EI, et al. Superiority of the buffy coat over serum or plasma for the detection of Alkhumra virus RNA using real time RT-PCR. Arch Virol 2012;157:819 23. 20. Allwinn R, Doerr HW, Emmerich P, Schmitz H, Preiser W. Cross-reactivity in flavivirus serology: new implications of an old finding? Med Microbiol Immunol 2002;190:199 202. 21. Kuno G. Serodiagnosis of flaviviral infections and vaccinations in humans. Adv Virus Res 2003;61:3 65.