Re: India Encephalitis 2014 - 2 fatalities
Re: India Encephalitis 2014 - 2 fatalities
ProMed commentary on the above article contains a wealth of background information;
Published Date: 2014-03-06 13:50:15
Subject: PRO/EDR> Acute encephalitis syndrome - India: (UP) R. prowazekii/head lice susp.
Archive Number: 20140306.2317645
ACUTE ENCEPHALITIS SYNDROME - INDIA: (UTTAR PRADESH) RICKETTSIA PROWAZEKII/HEAD LICE SUSPECTED
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[Rickettsial infections, including scrub typhus, endemic (or murine, flea-borne) typhus and Indian tick typhus caused by _Rickettsia conorii_, are known to be prevalent in various parts of India (
https://indianpediatrics.net/feb2010/157.pdf). ProMED-mail has extensively posted reports of outbreaks of acute encephalitis syndrome (AES) of unknown etiology in India (see prior ProMED-mail post Japanese encephalitis & other - India (22): (BR) 20131231.2145305 and others below). In past reports, the disease has been associated with Japanese encephalitis virus infections and with consumption of contaminated water, suggesting enterovirus infections. The above news reports says that a team of experts have attributed the cause of acute encephalitis syndrome (AES) in hundreds of children in eastern Uttar Pradesh, India in 2013 to _Rickettsia prowazekii_ infection, which they say was transmitted person-to-person by human head lice.
Lice found on each area of the body are different from each other. The three types of lice that live on humans are: _Pediculus humanus capitis_ (head louse), _Pediculus humanus corporis_ (body louse), and _Phthirus pubis_ ("crab" or pubic louse). Lice infestations are spread most commonly by close person-to-person contact or through shared clothing or personal items (such as hats or hairbrushes). A louse cannot jump or fly and dogs, cats, and other pets do not play a role in the transmission of human lice (
http://www.cdc.gov/parasites/lice/). Body lice live and lay eggs (nits) in the seams of clothing; they are usually not seen on the body, except when they feed; whereas head lice attach their eggs to the base of the hair shaft, and the lice and their eggs are usually found in hair. Head lice are common in preschool and elementary school-age children.
Head lice have not been previously known to transmit disease (
http://www.cdc.gov/parasites/lice/he...info/faqs.html), although secondary staphylococcal or streptococcal infection also may occur, usually limited to the scalp. Only the body louse was known to spread disease; body lice are vectors for: _R. prowazekii_, the cause of epidemic typhus; _Bartonella quintana_, the cause of trench fever; and _Borrelia recurrentis_, the cause of relapsing fever.
The news report does above not say how head lice were implicated in the outbreak of AES in India. However, specific PCR amplification and determination of the nucleotide base sequences of the amplification products has been used to detect bacterial DNA in lice; using this approach, the presence of _R. prowazekii_ was confirmed in body lice collected from refugees in Burundi, among whom typhus was epidemic (
http://www.ncbi.nlm.nih.gov/pubmed/9...?dopt=Abstract). ProMED-mail would be interested in exactly how infection with _R. prowazekii_ and head lice were implicated in the AES outbreak in India from knowledgeable sources.
Rickettsiae are obligate intracellular coccobacillary bacteria that have typical Gram negative cell walls, but do not stain well with Gram stain. They, however, appear red with Giemsa or Gimenez stains. Rickettsial diseases are usually transmitted to humans by arthropods. _R. prowazekii_ live in the alimentary tract of the body louse, which bites a human for a blood meal and causes an itchy reaction on the host's skin. The louse defecates as it eats; when the host scratches the site, and the rickettsia-laden louse feces is inoculated into the bite wound.
Rickettsiae invade endothelial cells that line the inner walls of blood vessels. The consequent vascular injury causes increases vascular permeability with consequent tissue edema, loss of blood volume, hypoalbuminemia, decreased osmotic pressure, hypotension, tissue hypoperfusion, and end-organ ischemia. This process leads to interstitial pneumonitis, noncardiogenic pulmonary edema, cerebral edema, and meningoencephalitis. Epidemic typhus is usually diagnosed by serology, such as, indirect fluorescence antibody test, complement fixation, and enzyme immunoassay (EIA). However, _R. prowazekii_ may cross-react with _Rickettsia typhi_ (the cause of murine typhus) (
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC95923/). _R. prowazekii_ can also be identified in tissue samples, including skin biopsies, by immunohistochemical staining and polymerase chain reaction (PCR) assays. Early treatment with antibiotics, such as doxycycline, is effective. The case-fatality rate is up to 40% in the absence of antibiotic treatment.
A new human-independent natural cycle of epidemic typhus has been described in flying squirrels and their ectoparasites. Flying squirrels are the only known vertebrate reservoir of _R. prowazekii_, other than humans, and contact with these animals has been linked to most sporadic epidemic typhus cases in the United States (
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3033063/). - Mod.ML]
Cases of AES in northeastern India (especially eastern Uttar Pradesh and Behar states) have seasonal occurrence, peaking in the warmest months and declining as ambient temperatures cool. No explanation is offered by the investigators of how body louse transmission of _R. prowazekii_ would be seasonal and why disease is limited to children. The epidemiological analysis that the report mentions provides no details. WHO indicates that a macular rash is a key sign of epidemic typhus, yet the reports of AES do not mention this in the cases they report. Clearly, laboratory diagnosis to determine the etiological agent(s) involved in these cases is needed. - Mod.TY
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http://healthmap.org/r/1-k3.]
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