Entomology and Vectorborne Diseases, USAMRU-K Jason Richardson Entomology & Vectorborne Diseases U.S. Army Medical Research Unit-Kenya Rift Valley fever

Entomology and Vectorborne Diseases, USAMRU-K

Jason RichardsonJason Richardson

Entomology & Entomology & Vectorborne DiseasesVectorborne Diseases

U.S. Army Medical Research U.S. Army Medical Research Unit-KenyaUnit-Kenya

Rift Valley fever outbreak Rift Valley fever outbreak responseresponse

Dec 2006 – Feb 2007Dec 2006 – Feb 2007


HighlightsHighlights Ken Linthicum is omnipotent. Last RVF outbreak in Kenya was in 1997/98. 14 Dec 2006 - Vector surveillance initiated in NE Kenya. 20 Dec 2006 - Fatalities due to an unexplained fever

confirmed as RVF. 14 Dec through today – Vector surveillance

4 ecologically distinct areas of Kenya. > 420 trap nights, > 40 collection sites, > 105,000 mosquitoes, sand flies, and biting midges, > 2,500 pools (760 already tested for RVFV) 30 RVFV positive pools, Virus isolated in cell culture, Virus sequenced

Outstanding team effort!



RVFV BackgroundRVFV Background Rift Valley Fever (RVF) is a viral zoonosis. Primarily affects livestock. It is spread by the bite of infected mosquitoes. The disease is caused by the RVF virus, a member of the

genus Phlebovirus (family Bunyaviridae). The disease was first reported among livestock in Kenya

around 1915, but the virus was not isolated until 1931. RVF outbreaks occur across sub-Saharan Africa, Egypt in 1977-78, several million people were infected and

thousands died during a violent epidemic. Saudi Arabia and Yemen – 2000.


RVF epidemic foci

(Clements et al., , 2006)


ImpactImpact

Approximately 1% of human sufferers Approximately 1% of human sufferers die of the disease. die of the disease.

Amongst livestock the fatality level is Amongst livestock the fatality level is significantly higher. significantly higher.

In pregnant livestock infected with In pregnant livestock infected with RVF RVF abortion rates approach 100%.abortion rates approach 100%.

An epizootic of RVF is usually first An epizootic of RVF is usually first indicated by a wave of unexplained indicated by a wave of unexplained abortions.abortions.


Transmission CycleTransmission Cycle

Epizootics are dependant on flooding and population densities of flood water Aedes species


Transmission CycleTransmission Cycle

No known vertebrate reservoir. Various competent vectors including Aedes, Culex, Mansonia,

Ochlerotatus spp. Sand flies, culicoides, ticks? Efficient mechanical transmission. Transovariol transmission in Ae. mcintoshi, Ae. vexans Blood and milk-borne. Aerosolized virus lab infections. Man is NOT a dead end host.


DamboDambo


Linthicum, K.J., A. Anyamba, C.J. Tucker, P.W. Linthicum, K.J., A. Anyamba, C.J. Tucker, P.W. Kelley, M.F. Meyers, C. J. Peters, 1999: Kelley, M.F. Meyers, C. J. Peters, 1999:

ScienceScience, 285, pp. 397-400 , 285, pp. 397-400



• A collaborative project between DoD-GEIS and NASA Goddard Space Flight Center.• The ability to map such areas of potential RVF activity 2 to 5 months before outbreaks occur.


Rainfall & “Greeness”Rainfall & “Greeness”

This Normalized Difference Vegetation Index (NDVI) anomaly map depicts the percent deviation or change from mean vegetation greenness


El Nino and Sea Surface El Nino and Sea Surface TemperaturesTemperatures



Outbreak ResponseOutbreak Response

Nov 06 – received an email from Dr. Nov 06 – received an email from Dr. Anyamba (GEIS/NASA) warning of a Anyamba (GEIS/NASA) warning of a possible RVF outbreak.possible RVF outbreak.

14 Dec 06 – USAMRU-K initiated 14 Dec 06 – USAMRU-K initiated vector collections in NE Kenya.vector collections in NE Kenya.

Aedes mcintoshiAedes mcintoshi populations were populations were overwhelming.overwhelming.

Human hemorrhagic fever cases Human hemorrhagic fever cases evident.evident.





Outbreak ResponseOutbreak Response

20 Dec 06 – First confirmed human case.20 Dec 06 – First confirmed human case. Surveillance Surveillance outbreak response outbreak response

planning.planning. Risk managementRisk management Interagency coord.Interagency coord.

CDCCDC USAMRIIDUSAMRIID NAMRU-3NAMRU-3 DOSDOS KMOH KMOH


KEMRI VHF Reference Lab (GEIS)

USAMRIID CDC, Ft Collins NAMRU-3

USAMRU-K, Vector-borne Disease Program



Surveillance in NE Kenya Surveillance in NE Kenya


Nomadic pastoralistsNomadic pastoralists


Typical “village”Typical “village”


Manyatta – Typical homeManyatta – Typical home


Herder hooch



Herders live on raw Herders live on raw blood & milkblood & milk


Dry ice is not Dry ice is not candycandy







Tick collectionsTick collections


SerosurvSerosurveyey




Driving to the coastDriving to the coast


Driving to the coastDriving to the coast


Life at the Life at the beachbeach


Kilifi RVF Case LocationsKilifi RVF Case Locations





Lab ResultsLab Results Tested 765 pools by real-time and Tested 765 pools by real-time and

conventional RT-PCR.conventional RT-PCR. Detected 30 positive pools (2 species not Detected 30 positive pools (2 species not

previously implicated as vectors).previously implicated as vectors). Aedes mcintoshi Aedes mcintoshi (11 pools)(11 pools), , Ae. ochraceus Ae. ochraceus (11 pools)(11 pools), , Ae. pembaensis Ae. pembaensis (1 pool)(1 pool), , An. squamosus An. squamosus (1 pool)(1 pool), , Culex bitaeniorhynchus Culex bitaeniorhynchus (3 pools)(3 pools),, Cx. poicilipesCx. poicilipes (3 pools). (3 pools).

12 of 21 sites tested had at least one 12 of 21 sites tested had at least one positive pool. positive pool.


Lab ResultsLab Results

Minimal field infection rate (MIR)Minimal field infection rate (MIR) MIR = (# pools pos/# of samples) * MIR = (# pools pos/# of samples) *

10001000 30 positive pools (25 per pool)30 positive pools (25 per pool) 19125 specimens tested (to date)19125 specimens tested (to date) MIR = 1.57MIR = 1.57


Lab Lab ResultsResults

Identified ~40,000 Identified ~40,000 arthropods to date.arthropods to date.

> 40 species> 40 species > 10,000 > 10,000

Ae. mcintoshiAe. mcintoshi

District

SPECIES Garissa Kilifi Kirinyaga Tana River

Grand Total

Ae. aedimorphus 7 7 Ae. aegypti 90 4 3 97 Ae. circumluteolus 124 4 128 Ae. mcintoshi 10936 4 1 10941 Ae. mucidus scatophagoides(sudanensis) 542 5 2 549 Ae. neomelaniconion 50 50 Ae. ochraceus 9557 1 4 9562 Ae. simpsoni 17 4 1 2 24 Ae. skusea pembaensis 1541 1541 Ae. stegomyia 58 6 2 66 Ae. vittatus 2 2 Aedes spp 72 220 18 310 Aediomyia furfurea 7 7 An. coustani 357 33 8 398 An. funestus 34 34 An. gambiae 753 49 162 1 965 An. maculipalpis 45 45 An. pharoensis 32 19 51 An. squamosus 2265 13 32 6 2316 Anopheles spp 434 2 26 462 Coquilletidia spp 1 1 2 Cq. fuscopennata 28 28 Culex spp 431 663 483 1577 Culicoides 82 75 157 Cx. annuloris 309 309 Cx. bitaeniorhynchus 511 533 56 1 1101 Cx. cx. culiciomyia macfiei 5 35 40 Cx. cx. fatigans/quinquefasciatus 35 332 154 521 Cx. duttoni 61 61 Cx. ethiopicus 100 100 Cx. neoculex 4 4 Cx. ochraceus 75 75 Cx. pipiens 1632 30 395 6 2063 Cx. poicilipes 4005 2565 4 1 6575 Cx. simpsoni 25 105 130 Cx. tigripes 4 47 51 Cx. univittatus 720 52 92 6 870 Cx. vansomerei 63 3 66 Eretmapodites chrysogaster 9 9 Eretmapodites 2 2 M. Africana 2 278 280 M. uniformis 149 149 Sand flies 8 16 167 191 To be identified 49378 1200 173 50751 Grand Total 82484 6708 3326 488 93006


Real-Time & Conventional RT-PCRKLF-014 (#4) 588F-946RC + 642 probeKLF-085 (#9) 588F-946RC + 642 probeKLF-091 (#15) 588F-946RC + 642 probeKLF-112 (#33) 588F-946RC + 642 probeneg cntl 588F-946RC + 642 probe

Collected in Kilifi on 13 January 2007

Species: Ae. pembaensis (lane 5);

Cx. bitaeniorhynchus (lane 10)

Sample: KLF014/04; KLF 085/09

Product 551 bp, Ibrahim et al. 1997


Deployable PCR LabDeployable PCR Lab








BSL-3 LabBSL-3 Lab


After virus inactivationAfter virus inactivation


Containment and SafetyContainment and Safety

RVFV RVFV BSL 3 BSL 3 Field (open air processing) Field (open air processing)

PPE PPE Prevent aerosolizationPrevent aerosolization Inactivate virusInactivate virus


Virus IsolationVirus Isolation

Vero cells

Negative control CPE from positive mosquito


Blast Report for RVFV Isolated in Blast Report for RVFV Isolated in Kenya 2007Kenya 2007


RVFV Sequence Alignment RVFV Sequence Alignment KEN-1998 and KEN-2007: M Segment

Sequencing was conducted at KEMRI, Nairobi, Kenya

- Nucleotide Substitutions


Documents

Entomology and Vectorborne Diseases, USAMRU-K Jason Richardson Entomology & Vectorborne Diseases U.S. Army Medical Research Unit-Kenya Rift Valley fever