Ancestral Dengue Virus, Malaysia | CDC EID

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Volume 16, Number 11–November 2010
Dispatch
Isolation of Ancestral Sylvatic Dengue Virus Type 1, Malaysia

Boon-Teong Teoh, Sing-Sin Sam, Juraina Abd-Jamil, and Sazaly AbuBakar Comments to Author
Author affiliation: University of Malaya, Kuala Lumpur, Malaysia

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Abstract
Ancestral sylvatic dengue virus type 1, which was isolated from a monkey in 1972, was isolated from a patient with dengue fever in Malaysia. The virus is neutralized by serum of patients with endemic DENV-1 infection. Rare isolation of this virus suggests a limited spillover infection from an otherwise restricted sylvatic cycle.

Dengue virus (DENV) is a mosquito-borne pathogen maintained in sylvatic (nonhuman primate/sylvatic mosquitoes) and endemic (human/urban/peridomestic mosquitoes) cycles. The endemic form of DENV poses a serious health threat to >100 million persons living in dengue-endemic regions (1). The endemic form of DENV may have originated from adaptation of sylvatic DENV to either peridomestic/urban mosquitoes or nonhuman primate hosts 100–1,500 years ago (2).

All 4 DENV genotypes are thought to have independently evolved from a sylvatic ancestral lineage, perhaps in Malaysia (2). However, only sylvatic DENV-1, DENV-2, and DENV-4 have been isolated, and monkey seroconversion against DENV-1, DENV-2, and DENV-3 has been demonstrated (3). Incidences of spillover infection involving sylvatic DENV-2 have been reported, but mainly in West Africa.

Sylvatic dengue may still be endemic to West Africa, especially in areas with dense human habitation near forest areas (4,5). Sporadic reports of sylvatic dengue may be the result of low incidence of severe forms of this disease in these regions. In contrast, infection with sylvatic dengue is rare in other parts of the world, especially in Southeast Asia where dengue is hyperendemic. Sylvatic DENVs (DENV-1, DENV-2, and DENV-4) were last isolated from monkeys in Malaysia in the 1970s (3).

During 2004–2007, a dramatic increase occurred in the number of suspected dengue cases in Malaysia; 155,424 cases and 358 deaths were reported (6). DENV-1 was the predominant virus isolated and accounted for 68% of all DENVs isolated. This outbreak represented a third cycle that involved DENV-1 in Malaysia since the 1960s (7). We report isolation of DENV-1 that shared >97% genome sequence similarity to an ancestral DENV-1 isolated from a sentinel monkey in Malaysia in 1972 (3).

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Suggested Citation for this Article

Teoh B-T, Sam S-S, Abd-Jamil J, AbuBakar S. Isolation of ancestral sylvatic dengue virus type 1, Malaysia. Emerg Infect Dis [serial on the Internet]. 2010 Nov [date cited]. http://www.cdc.gov/EID/content/16/11/1783.htm

DOI: 10.3201/eid1611.100721