Prevalence of Zoonotic and Vector-Borne Infections Among Afghan National Army Recruits in Afghanistan

To measure prevalence of prior/current Plasmodium vivax and Plasmodium falciparum (PV and PF), Brucella spp. (BR), dengue virus (DENV), Leishmania donovani (visceral leishmaniasis; VL), and Crimean-Congo hemorrhagic fever (CCHF) virus exposure among Afghan National Army (ANA) recruits.

Randomly chosen, nationally representative serum samples from consenting men aged 18-40 years and who were screened between February 2010 and January 2011 were tested, with ∼25 samples/province. Samples were screened for PV and PF antigens and VL antibody with rapid diagnostic tests. Reactive malaria screening results were confirmed with polymerase chain reaction assay. Enzyme-linked immunosorbent assays were used to screen for CCHF and DENV antibodies; reactive DENV samples were confirmed with the plaque-reduction neutralization test. BR screening and confirmatory testing was performed with slide and tube agglutination, respectively. Correlates of BR titres >1:80 were analyzed using logistic regression.

Of 809 participants contributing specimens, 62% had previously lived outside Afghanistan, predominantly in Pakistan and Iran. CCHF (4.1%, n = 33), DENV (2.1%, n = 17), and VL (1.0%, n = 8) antibody prevalence was low. For PV and PF, only 7 out of 56 reactive samples had detectable nucleic acid. For BR, 8.0% (n = 65) of samples had screening titers >1:40, of which 83.1% had confirmatory titers >1:80. Participants from Kabul and surrounding provinces had lower odds (OR = 0.19, 95% CI: 0.04-1.00) of BR antibody compared with other regions.

BR exposure was relatively common with a nearly national distribution, whereas geographic distribution for other pathogens aligned roughly with the expected vector distribution. Public health protection measures should include vector control, food safety, and enhanced diagnostics for acute febrile illness.