Chikungunya virus, Cameroon, 2006.We report the isolation of chikungunya
adj. 1. Of or relating to phylogeny or phylogenetics. 2. Relating to or based on evolutionary development or history: a phylogenetic classification of species. grouped in the Democratic Republic of the Congo cluster, indicating a continuous circulation of a genetically similar chikungunya virus population during 6 years in Central Africa. ********** Chikungunya virus (CHIKV), formerly only an anecdotally described arbovirus arbovirus Any of a large group of viruses that develop in arthropods (chiefly mosquitoes and ticks). The name derives from “arthropod-borne virus.” The spheroidal virus particle is encased in a fatty membrane and contains RNA; it causes no apparent harm to the , is now a worldwide public health problem (1). Recently, numerous cases of CHIKV infection have been reported from a major outbreak of febrile febrile /feb·rile/ (feb´ril) pertaining to or characterized by fever. feb·rile adj. Of, relating to, or characterized by fever; feverish. illness around the Indian Ocean, which included Comoros, Mauritius, Reunion Island (2,3), and southern India (4). CHIKV is widely distributed in tropical Africa (5,6) and in Asia (7). In Africa, until 2000, the virus was described as endemic, perpetuated through a sylvatic sylvatic /syl·vat·ic/ (sil-vat´ik) sylvan; pertaining to, located in, or living in the woods. sylvatic found in the woods; occurring in animals of the forest. cycle involving wild primates, humans, and mosquitoes of the genus Aedes (2,8). During the past 6 years, the urban cycle has also tended to play a role in Central Africa (6). Nevertheless, although recent serologic se·rol·o·gy n. pl. se·rol·o·gies 1. The science that deals with the properties and reactions of serums, especially blood serum. 2. surveys suggest a high prevalence of Togaviridae, Flaviviridae, and Bunyaviridae (9,10), understanding of the circulation and effects of arboviruses arboviruses (ar´bōvī´r  sz),n. in Cameroon remains imprecise. This lack of understanding may reflect confusion between arboviral infections and hyperendemic Plasmodium falciparum Plasmodium fal·cip·a·rum n. A protozoan that causes falciparum malaria. infection. We report the first isolation, to our knowledge, of CHIKV in Cameroon. The virus was identified during an outbreak of a febrile syndrome in French soldiers in Douala and in patients from an urban medical center in Yaounde. We also found evidence of cocirculation of CHIKV and dengue virus dengue virus n. A virus of the genus Flavivirus that is the cause of dengue. (DENV DENV Department of Environment (Canada) ). The Study In Douala, Cameroon, 2 sporadic cases of a dengue-like syndrome were recorded in French soldiers (patients 1 and 2) on April 3 and May 22, 2006, respectively (Table). From the end of May through the end of July 2006, more cases of denguelike syndrome, which included fever, asthenia asthenia /as·the·nia/ (as-the´ne-ah) lack or loss of strength and energy; weakness. neurocirculatory asthenia , maculopapular rashes, and arthralgia arthralgia /ar·thral·gia/ (ahr-thral´jah) pain in a joint. ar·thral·gia n. Severe pain in a joint. Also called arthrodynia. , were observed in Yaounde. The number of patients who sought treatment at the Yaounde Medical Center peaked in mid-June 2006. Blood samples were collected from 30 of the 40 patients who visited the medical center. The 30 patients' ages ranged from 1 to 54 years. The delay between the onset of symptoms and the sampling ranged from 0 to 39 days with a median of 4 days (Table). All but 1 patient lived in Yaounde, and none of these patients had a history of travel abroad or from Yaounde. Nine patients were Cameroonian, and all other patients were from other countries; 15 patients were female. A blood sample from a 53-year-old woman who returned to France from Yaounde was also received. All patients had negative results for P. falciparum according to rapid test (Core Malaria Pf, Core Diagnostics, Birmingham, UK) and thick smear examination. Serum specimens were tested for immunoglobulin M immunoglobulin M n. Abbr. IgM The class of antibodies found in circulating body fluids and the first antibodies to appear in response to an initial exposure to an antigen. (IgM) and IgG antibodies specific for DENV, West Nile virus West Nile virus, microorganism and the infection resulting from it, which typically produces no symptoms or a flulike condition. The virus is a flavivirus and is related to a number of viruses that cause encephalitis. (WNV WNV West Nile Virus WNV World Net Visions ), Wesselsbron virus, Rift Valley fever Rift Valley fever An arthropod-borne (primarily mosquito), acute, febrile, viral disease of humans and numerous species of animals. Rift Valley fever is caused by a ribonucleic acid (RNA) virus in the genus Phlebovirus of the family Bunyaviridae. virus, Bunyamwera virus, and CHIKV by IgM-antibody capture (MAC-ELISA) and IgG sandwich ELISA ELISA (e-li´sah) Enzyme-Linked Immuno-Sorbent Assay; any enzyme immunoassay using an enzyme-labeled immunoreactant and an immunosorbent. ELISA n. , respectively (11). A serum sample was consider positive if the optical density (OD) ratio of viral antigen viral antigen n. Abbr. VA An antigen with multiple antigenicities that is protein in nature, strain-specific, and closely associated with the virus particle. to uninfected cells was >3. The presence of CHIKV, DENV, and WNV genomes was tested for by specific real-time reverse transcription PCR PCR polymerase chain reaction. PCR abbr. polymerase chain reaction Polymerase chain reaction (PCR) (RT-PCR RT-PCR reverse transcriptase-polymerase chain reaction. See PCR1. ) (12). Virus isolation on C6/36 and Vero cells was attempted on samples that were positive by RTPCR RTPCR Reverse Transcriptase Polymerase Chain Reaction (11). The serologic follow-up of patient 1 (Table) for a 3-week period detected seroconversion seroconversion /se·ro·con·ver·sion/ (-con-ver´zhun) the change of a seronegative test from negative to positive, indicating the development of antibodies in response to immunization or infection. to a virus antigenically related to CHIKV virus (the OD ratios obtained with the second sample were >3) for IgM and IgG. A sample from patient 2 was obtained the day after the onset of symptoms, and no antibodies to all tested arboviruses were detected. However, the specimen was positive by real-time RT-PCR for CHIKV. The patient's sample yielded CHIKV when cultured, and the envelope gene was partially sequenced (position 10,238-11,367, GenBank accession no. EF051584). The 1.2-kb sequence genetic analysis did not show any codon codon: see nucleic acid. deletion or insertion when compared with other African CHIKV sequences available in the GenBank database (3,6,8). A high degree of identity was observed when the sequence was compared with the Democratic Republic of the Congo (DRC DRC Democratic Republic of Congo DRC Down (Stage) Right Center DRC Director(ate) of Reserve Components DRC Disability Rights Commission (United Kingdom) ) strains isolated in 2000 (6). Paired identity ranged from 97% to 98.1% at the nucleotide level and from 98.7% to 99.3% at the amino acid level. The Cameroon isolate displayed a higher nucleotide divergence (paired identity ranging from 95% to 95.5%) when compared with the 2006 Reunion Island strains (2,3,13). However, amino acid sequences were highly conserved (99%-99.5%). The sequence identity among these isolates highlights their common origin and particularly the genetic stability of CHIKV despite the 6 years and the geographic distance from the DRC outbreaks. As shown in the phylogenetic tree (Figure), the CHIKV Cameroon strain clustered with DRC CHIKV strains with a high bootstrap See boot. (operating system, compiler) bootstrap - To load and initialise the operating system on a computer. Normally abbreviated to "boot". From the curious expression "to pull oneself up by one's bootstraps", one of the legendary feats of Baron von Munchhausen. value of 100. This genotype of CHIKV was closely related to strains from the Central African Republic Central African Republic, republic (2005 est. pop. 3,800,000), 240,534 sq mi (622,983 sq km), central Africa. The landlocked nation is bordered by Chad (N), Sudan (E), Congo (Kinshasa) and Congo (Brazzaville) (S), and Cameroon (W). and the 1982 Uganda isolate (6,8). The close genetic relationship suggests a continuous circulation of a homologous CHIKV population in Central Africa with a high degree of genetic stability. The genetic stability of the Central African CHIKV strains during 24 years, whether associated with epidemic or sporadic cases, highlights the peculiar importance of the few mutations detected in the recent Reunion Island isolates (3). This also suggests that the Central African strain CHIKV zone of circulation now includes India (4), the Indian Ocean, and Cameroon. [FIGURE OMITTED] The phylogenetic tree also illustrates the differences between the Cameroon isolates and the Asian subgroup isolates. Moreover, when compared with Asian CHIKV, including the 2006 isolates, the Cameroon strain showed 91%-91.9% and 96.8%-98.8% identity at the nucleotide and amino acid levels, respectively. Despite the similarity, cross-neutralization experiments must be conducted to confirm the protective effect of the Asian CHIKV-based vaccine against Central African strains (2). Among patients from Yaounde, 1 (patient 11) had only IgM antibodies specific to CHIKV, while patients 18 and 28 had both IgM and IgG antibodies specific to CHIKV (Table). One patient from Cameroon (patient 20) had IgG specific to both CHIKV and flavivirus. Three patients (nos. 6, 13, and 15), 2 of whom were Cameroonian, had antibodies specific for flavivirus. All samples were negative for WNV and CHIKV by RT-PCR. One sample (from patient 31) was positive for DENV; however, no virus was detected by cell culture. These results suggested a cocirculation of CHIKV and dengue virus during the same period, which is consistent with the suspected circulation of dengue virus, CHIKV, and yellow fever virus yellow fever virus n. An arbovirus of the genus Flavivirus that causes yellow fever and is transmitted by mosquitoes. observed in a study from 2000 through 2003 in Cameroon (9). In Cameroon, as in DRC (6), patients were likely infected in urban or periurban centers (Yaounde, the capital of Cameroon Noun 1. capital of Cameroon - the capital of Cameroon Yaounde Cameroun, Republic of Cameroon, Cameroon - a republic on the western coast of central Africa; was under French and British control until 1960 ; Douala, a major city). These infections occurred in a context where Aedes albopictus tends to replace indigenous Ae. aegypti in rural and urban Cameroonian environments (14). This finding suggests that urban cycles and urban vectors, in addition to the traditional forest-dwelling vectors, may play an important role in the maintenance and amplification of CHIKV in Africa. Conclusions Since its first isolation in 1953 (8), CHIKV has been isolated in different Central African countries (8,6). Until now, only 2 alphavirus strains antigenically suspected to be CHIKV had been isolated from human patients in Cameroon (15). Recent serosurvey studies suggested a possible CHIKV circulation in Cameroon (9,10). Our Cameroon CHIKV isolate confirmed its circulation in this country. Our study suggests a 6-year continuous circulation of genetically stable and indigenous strains in Central Africa rather than importation of CHIKV from the recent Indian Ocean or Asian outbreaks. Moreover, the genetic stability of the Central African CHIKV highlights the importance of the unique molecular features that was shown in Reunion Island isolates (3). Acknowledgments We are indebted to Jon Davis for manuscript revision. References (1.) Gubler DJ. The global emergence/resurgence of arboviral diseases as public health problems. Arch Med Res. 2002;33:330-42. (2.) Bessaud M, Peyrefitte CN, Pastorino BAM Bam (bäm), town (1996 pop. 70,100), Kerman prov., SE Iran, on the intermittent Bam River. Located on the western edge of the Dasht-e Lut, Bam is a trade center in a henna-growing region. Dates and other fruits are also grown; camels are raised. , Tock F, Merle merle a pattern of coat color pigmentation with dark, irregular blotches on a lighter background. Seen in some Collies and Welsh corgis. In shorthaired dogs, e.g. Great Danes and Dachshunds, the similar pattern is called dapple. O, Colpart JJ, et al. Chikungunya virus strains, Reunion Island outbreak. Emerg Infect Dis. 2006; 12:1604-6. (3.) Schuffenecker I, Iteman I, Michault A, Murri S, Frangeul L, Vancy MC, et al. Genome microevolution mi·cro·ev·o·lu·tion n. Evolution resulting from a succession of relatively small genetic variations that often cause the formation of new subspecies. of chikungunya viruses causing the Indian Ocean outbreak. PLoS Med. 2006;3 :e263. (4.) Yergolkar PN, Tandale BV, Arankalle VA, Sathe PS, Sudeep AB, Ganghe SS, et al. Chikungunya outbreaks caused by African genotype, India. Emerg Infect Dis. 2006; 12:1580-3. (5.) Saluzzo JF, Adam C, Castagnet P, Chapelle P, Cornet M, Heme heme: see coenzyme. G, et al. Une poussee epidemique due au virus chikungunya dans l'ouest du Senegal en 1982. Med Afr Noire. 1982;30:427-30. (6.) Pastorino B, Muyembe-Tamfum JJ, Bessaud M, Tock F, Tolou H, Durand JP, et al. Epidemic resurgence of Chikungunya virus in Democratic Republic of the Congo: identification of a new central African strain. J Med Virol. 2004;74:277-82. (7.) Lam SK, Chuah KB, Hooi PS, Rahimah MA, Kumari S, Tharmaratnam M, et al. Chikungunya infection--an emerging disease in Malaysia. Southeast Asian J Trop Med Public Health. 2001 ;32:447-51. (8.) Powers AM, Brault AC, Tesh RB, Weaver SC. Re-emergence of Chikungunya and O'nyong-nyong viruses: evidence for distinct geographical lineages and distant evolutionary relationships. J Gen Virol. 2000;81:471-9. (9.) Kuniholm MH, Wolfe ND, Huang CYH CYH Check Your Head (youth driven organization in Canada) CYH Consider Yourself Hugged , Mpoudi-Ngole E, Tamoufe U, Burke DS, et al. Seroprevalence seroprevalence Immunology The proportion of a population that is seropositive–ie, has been exposed to a particular pathogen or immunogen; the seropositivity of a population is calculated as the number of individuals who produce a particular antibody divided and distribution of Flaviviridae, Togaviridae, and Bunyaviridae arboviral infections in rural Cameroonian adults. Am J Trop Med Hyg. 2006;74:1078-83. (10.) Ndip LM, Bouyer DH, Travassos Da Rosa APA (All Points Addressable) Refers to an array (bitmapped screen, matrix, etc.) in which all bits or cells can be individually manipulated. APA - Application Portability Architecture , Titanji VPK VPK Vapaaehtoinen Palokunta (Voluntary Fire Brigade in Finnish) VPK Voluntary Pre-Kindergarten program VPK Vehicle Per Kilometer VPK Vänster Partiet Kommunisterna (former Swedish Communist Party) , Tesch RB, Walker DH. Acute spotted fever rickettsiosis rickettsiosis /rick·ett·si·o·sis/ (ri-ket?se-o´sis) infection with rickettsiae. rick·ett·si·o·sis n. Infection with Rickettsia bacteria. among febrile patients, Cameroon. Emerg Infect Dis. 2004; 10:432-7. (11.) Peyrefitte CN, Pastorino BAM, Bessaud M, Gravier P, Tock F, Couissinier-Paris P, et al. Dengue dengue or breakbone fever or dandy fever Infectious, disabling mosquito-borne fever. Other symptoms include extreme joint pain and stiffness, intense pain behind the eyes, a return of fever after brief pause, and a characteristic rash. type 3 virus, Saint Martin, 2003-2004. Emerg Infect Dis. 2005; 11:757-61. (12.) Pastorino B, Bessaud M, Grandadam M, Murri S, Tolou HJ, Peyrefitte CN. Development of a TaqMan RT-PCR assay without RNA RNA: see nucleic acid. RNA in full ribonucleic acid One of the two main types of nucleic acid (the other being DNA), which functions in cellular protein synthesis in all living cells and replaces DNA as the carrier of genetic extraction step for the detection and quantification of African Chikungunya viruses. J Virol Methods. 2005; 124:65-71. (13.) Parola P, de Lamballerie X, Jourdan J, Rovery C, Vaillant V, Minodier P, et al. Novel chikungunya virus variant in travelers returning from Indian Ocean islands. Emerg Infect Dis. 2006; 12:1493-9. (14.) Simard F, Nchoutpouen E, Toto JC, Fontenille D. Geographic distribution and breeding site preference of Aedes albopictus and Aedes aegypti (Diptera: Culicidae) in Cameroon, Central Africa. J Med Entomol. 2005;42:726-31. (15.) Digoutte JP. In: Pasteur Institute and IRD IRD Institut de Recherche pour le Développement (French) IRD Inland Revenue Department (New Zealand's tax revenue collection department) IRD Integrated Receiver Decoder . CRORA (Centre collaborateur OMS OMS - Opportunity Management System de reference et de recherche pour les arbovirus et les virus de fievres hemorragiques) database. [cited 2007 Mar 21]. Available from http://www.pasteur.fr/recherche/banques/CRORA Dr Peyrefitte is involved in the diagnosis and epidemiology of arboviruses. He also researches arbovirus-cell interactions. Address for correspondance: Marc Grandadam, Unite de Virologie Tropicale, IMTSSA, BP 46, 13 998 Marseille Armees, France; email: publi.viro@laposte.net Use of trade names is for identification only and does not imply endorsement by the Public Health Service or by the U.S. Department of Health and Human Services Noun 1. Department of Health and Human Services - the United States federal department that administers all federal programs dealing with health and welfare; created in 1979 Health and Human Services, HHS . Christophe N. Peyrefitte, * Dominique Rousset, ([dagger]) Boris A.M. Pastorino, * Regis Pouillot, ([dagger]) Mael Bessaud, * Fabienne Tock, * Helene Mansaray, ([double dagger]) Olivier L. Merle, * Aurelie M. Pascual, * Christophe Paupy, ([section]) Aurelia Vessiere, ([dagger]) Patrice Imbert, ([paragraph]) Patrice Tchendjou, ([dagger]) Jean-Paul Durand, * Hugues J. Tolou, * and Marc Grandadam * * Institut de Medecine Tropicale du Service de Sante des Armees, Marseille, France; ([dagger]) Centre Pasteur du Cameroun, Yaounde, Cameroon; ([double dagger]) Centre Medico Social, Yaounde, Cameroon; ([section]) Institut de Recherche pour le Developpement, Yaounde, Cameroon; and ([paragraph]) Hopital d'Instruction des Armees Begin, St. Mande, France
Table. Characteristics of patients with febrile acute denguelike
syndrome, Cameroon, 2006 *
Symptom
Patient no. Sex/age, y City onset
1 M/35 Douala 3 Apr
1 M/35 Douala 3 Apr
2 ([section]) M/36 Douala 22 May
3 F/54 Yaounde 11 Jun
4 F/49 Yaounde 10 Jun
5 F/42 Yaounde 11 Jun
6 F/41 Yaounde 7 Jun
7 M/38 Yaounde 15 Jun
8 M/30 Yaounde 18 Aug
9 M/21 Yaounde 15 Jun
10 F/32 Yaounde 21 Jun
11 F/22 Yaounde 19 Jun
12 F/53 Imported 20 Jun
13 M/42 Yaounde 24 Jun
14 F/42 Yaounde 18 Jun
15 F/27 Yaounde 18 Jun
16 F/43 Yaounde 26 Jun
17 M/31 Yaounde 16 Jun
18 F/37 Yaounde 22 May
19 F/45 Yaounde 10 Jun
20 M/45 Yaounde 22 Jun
21 M/1 Yaounde 23 Jun
22 F/9 Yaounde 10 Jun
23 M/4 Yaounde 26 Jun
24 M/54 Yaounde 4 Jul
25 F/45 Yaounde 14 Jun
26 M/48 Yaounde 24 Jun
27 M/20 Yaounde 30 Jun
28 M/37 Yaounde 4 Jul
29 M/36 Yaounde 9 Jul
30 M/33 Yaounde 28 Jun
31 M/32 Yaounde 10 Jul
32 F/38 Yaounde 16 Jul
33 M/45 Yaounde 21 Jul
Sampling IgM
Patient no. date Delay, d ([dagger])
1 7 Apr 4 Neg
1 11 May 21 Pos CHIKV
2 ([section]) 23 May 1 Neg
3 12 Jun 1 Neg
4 13 Jun 3 Neg
5 12 Jun 1 Neg
6 7 Jun 0 Neg
7 19 Jun 4 Neg
8 19 Jun 1 Neg
9 19 Jun 4 Neg
10 22 Jun 1 Neg
11 26 Jun 7 Pos CHIKV
12 26 Jun 6 Pos CHIKV
13 27 Jun 3 Neg
14 28 Jun 10 Neg
15 29 Jun 11 Neg
16 30 Jun 4 Neg
17 30 Jun 14 Neg
18 30 Jun 39 Pos CHIKV
19 30 Jun 20 Neg
20 30 Jun 8 Neg
21 30 Jun 7 Neg
22 30 Jun 20 Neg
23 30 Jun 4 Neg
24 6 Jul 2 Neg
25 5 Jul 21 Neg
26 6 Jul 12 Neg
27 1 Jul 1 Neg
28 11 Jul 7 Pos CHIKV
29 11 Jul 2 Neg
30 10 Jul 12 Neg
31 12 Jul 2 Neg
32 17 Jul 1 Neg
33 26 Jul 5 Nea
IgG PCR
Patient no. ([dagger]) ([double dagger])
1 Neg Neg
1 Pos CHIKV Neg
2 ([section]) Neg Pos CHIKV
3 Neg Neg
4 Neg Neg
5 Neg Neg
6 Pos Flavi Neg
7 Neg Neg
8 Neg Neg
9 Neg Neg
10 Neg Neg
11 Neg Neg
12 Pos CHIKV Neg
13 Pos Flavi Neg
14 Neg Neg
15 Pos Flavi Neg
16 Neg Neg
17 Neg Neg
18 Pos CHIKV Neg
19 Neg Neg
20 Pos Flavi Neg
and CHIKV
21 Neg Neg
22 Neg Neg
23 Neg Neg
24 Neg Neg
25 Neg Neg
26 Neg Neg
27 Neg Neg
28 Pos CHIKV Neg
29 Neg Neg
30 Neg Neg
31 Neg Pos DENY
32 Neg Neg
33 Nea Neg
* IgM, immunoglobulin M; Neg, negative; Pos, positive; CHIKV,
chikungunya virus; Flavi, flavivirus; DENV, dengue virus.
([dagger]) DENV, West Nile virus, Wesselsbron virus, Rift Valley
fever virus, Bunyamwera virus, and CHIKV antibodies tested.
([double dagger]) DENV, West Nile virus, CHIKV tested by real-time
reverse transcription-PCR.
([section]) CHIKV isolation successful.
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