Unusual pattern of chikungunya virus epidemic in the Americas, the Panamanian experience

Abstract

BackgroundChikungunya virus (CHIKV) typically causes explosive epidemics of fever, rash and polyarthralgia after its introduction into naïve populations. Since its introduction in Panama in May of 2014, few autochthonous cases have been reported; most of them were found within limited outbreaks in Panama City in 2014 and Puerto Obaldia town, near the Caribbean border with Colombia in 2015. In order to confirm that Panama had few CHIKV cases compared with neighboring countries, we perform an epidemiological analysis of chikungunya cases reported from May 2014 to July 2015. Moreover, to understand this paucity of confirmed CHIKV cases, a vectorial analysis in the counties where these cases were reported was performed.MethodsChikungunya cases were identified at medical centers and notified to health authorities. Sera samples were analyzed at Gorgas Memorial Institute for viral RNA and CHIKV-specific antibody detection.ResultsA total of 413 suspected cases of CHIKV infections were reported, with incidence rates of 0.5 and 0.7 per 100,000 inhabitants in 2014 and 2015, respectively. During this period, 38.6% of CHIKV cases were autochthonous with rash and polyarthralgia as predominant symptoms. CHIKV and DENV incidence ratios were 1:306 and 1:34, respectively. A phylogenetic analysis of E1/E2 genomic segment indicates that the outbreak strains belong to the Asian genotype and cluster together with CHIKV isolates from other American countries during the same period. Statistical analysis of the National Vector Control program at the district level shows low and medium vector infestation level for most of the counties with CHIKV cases. This index was lower than for neighboring countries.ConclusionsPrevious training of clinical, laboratory and vector workers allowed a good caption and detection of the chikungunya cases and fast intervention. It is possible that low/medium vector infestation level could explain in part the paucity of chikungunya infections in Panama.

Human and Equine Infection with Alphaviruses and Flaviviruses in Panamá during 2010: A Cross-Sectional Study of Household Contacts during an Encephalitis Outbreak

“…Overall, our results are consistent with MADV being the principal etiologic agent of the 2010 Panamanian equine epizootic. 8,12,23,29 Our results suggest that WNV also circulates in Panamá, with seropositive horses in Coclé. A high prevalence of HI antibodies against SLEV was also detected (63.0%), consistent with the co-circulation of SLEV reported during previous MADV epizootics in Panamá.…”

“…28 However, human infection has not been detected in Panamá despite surveillance and epidemiologic investigations for alphavirus infections. 8,28,29 Our results highlight the need for further investigation of MAYV epidemiology in Panamá to assess its potential to cause outbreaks of severe, chronic arthralgia, as observed in South America. 4 A recent report of MAYV infection in Haiti suggests the possibility of recent spread.…”

Evolutionary analysis of the Chikungunya virus epidemic in Mexico reveals intra-host mutational hotspots in the E1 protein

“…We sought to gain insights into CHIKV evolution by analysing the emergent epidemic in Mexico, where over 11,000 confirmed cases were reported in 2015, the highest number in any country that year [19]. As seen in other non-endemic countries, with the exception of Panama[20], CHIKV spread rapidly to tropical regions nationwide. The endemicity of the primary vector Ae .…”

Genomic epidemiology of Chikungunya virus in Colombia reveals genetic variability of strains and multiple geographic introductions in outbreak, 2014

“…On May 13, 2014, Panama reported its first imported cases passengers coming from the Dominican Republic and Haiti 29 . Colombia’s first imported cases came from Venezuela, the Dominican Republic, and Panama and were reported more than two months later, in late July 19 .…”