Published Date: 2007-07-18 20:00:03
Subject: PRO/AH/EDR> Epidemic typhus, scrub typhus - India (Kerala)
Archive Number: 20070718.2307
EPIDEMIC TYPHUS, SCRUB TYPHUS - INDIA (KERALA)
A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
Date: Tue 17 Jul 2007
Source: The Times of India [edited]
The Health Minister told the state assembly [in Thiruvananthapuram]
that cases of typhus have been confirmed in the state [Kerala]. "A
child has died of typhus fever in Kozhikode and suspected cases of
scrub typhus disease have been spotted at 3 places in
Thiruvananthapuram," said Health Minister, PK Sreemathi. "We have
also asked the Kozhikode unit of the National Institute of
Communicable Disease to conduct a study to see if typhus fever has
spread," the minister added.
ProMED-mail Rapporteur Brent Barrett
[There are 5 diseases with typhus literally, or figuratively, in
their names: epidemic typhus, Brill-Zinsser disease (recrudescent
epidemic typhus), murine typhus, scrub typhus, and typhoid (so-called
because it is typhus-like and sometimes called abdominal typhus). The
term typhus comes from the Greek, _typhein_ (to smoke), which may
refer to the smoky or clouded mental status that patients present
Typhus fever, the classical epidemic typhus, is a vectorborne disease
with a complex epidemiology. Lice, the vectors, live in clothing;
therefore weather, humidity, and hygiene determine their prevalence.
Consequently, the body or clothing louse is more prevalent during the
colder months, and epidemic typhus is more frequently reported during
the winter and early spring.
The permanent foci of the body louse exist in regions subject to cold
weather, where inhabitants need to wear multiple layers of clothes,
and in poverty-stricken communities whose inhabitants lack multiple
sets of clothes. Such populations are most common in mountainous
regions of countries in intertropical zones, including Ethiopia,
Burundi, and Rwanda in Africa, Peru in South America, and Nepal and
Tibet in central Asia. The prevalence of body lice increases with
altitude. Infestation with lice is more frequent during wars, in
trenches, and in jail, where conditions are cramped, when it is cold,
and where hygiene is limited. Large outbreaks of lice have been
associated with the recent civil wars in Burundi. An outbreak of
typhus occurred in a jail in Burundi, and subsequently, a huge
outbreak of typhus occurred in several refugee camps where nearly all
inhabitants were louse-infested.
The body louse attaches its eggs to clothing, not to the body or
hair, often on the inner belts of underwear, pants or skirts. When
removed from the body, even in the absence of insecticides, the
unwashed clothes will [lose all] viable lice and eggs within 7
days. Raoult and Roux (1) cite Maunder (2), who hypothesized that
religious Sabbath and Sunday ritual days of rest with a change of
clothes could [have contributed] to a delousing cycle.
_Rickettsia prowazekii_, the causative agent of typhus fever, is
considered a category B biowarfare agent because of the propensity
for infective louse feces to be aerosolized.
Scrub typhus is spread to humans as a zoonosis by the bite of the
larval stage of trombiculid mites (chiggers). The term scrub comes
from the type of local vegetation, scrub, between forests and cleared
areas, where the vector is found. The disease is also referred to as
tsutsugamushi fever. The organism, _R. tsutsugamushi_, or _Orientia
tsutsugamushi_, causes natural disease in eastern Asia and in the
western Pacific. In any area, because of high rates of transovarian
transmission in the mite, highly focal areas of high risk exist.
Symptoms are often nonspecific, but severe headache and myalgias
(common in rickettsioses), and an eschar [dry scab] with regional
lymphadenopathy [swollen lymph nodes in the same area], can be helpful
to diagnosis in endemic areas. The diagnosis can be made
serologically, although early treatment (doxycycline) may blunt the
Weil and Felix described the classical assay for rickettsial antibody
detection in 1916. The methodology took advantage of heterophilic
(cross-reacting) antigens of members of the genus _Rickettsia_ and
several species of the Gram-negative bacillus _Proteus_. In the
Weil-Felix test, bacteria of _Proteus vulgaris_ OX-19 agglutinate with
sera of those infected with the typhus group organisms and with the
Rocky Mountain Spotted Fever (RMSF) organism _R. rickettsii_. Cells of
_P. vulgaris_ OX-2, on the other hand, agglutinate with sera from
individuals with spotted fever infection, except RMSF. The OX-19
agglutination is seen in epidemic typhus, but usually not in
Brill-Zinsser recrudescent disease. _P. mirabilis_ OX-K can be
similarly used in the serological diagnosis of scrub typhus. Because
of the relatively poor sensitivity, and specificity, of this test,
more specific assays can be used for diagnosis, including complement
fixation. Dipstick ELISA (enzyme-linked immunosorbent assay) assays
(3) and PCRs (polymerase chain reaction) (4) have now been added to
potential diagnostic tests.
1. Raoult D, Roux V: The body louse as a vector of reemerging human
diseases. Clin Infect Dis 1999; 29: 888-911.
2. Maunder JW: The appreciation of lice. Proc Roy Inst Great Britain.
1983; 55: 1-31.
3. Pradutkanchana J, Silpapojakul K, Paxton H, et al: Comparative
evaluation of 4 serodiagnostic tests for scrub typhus in Thailand.
Trans R Soc Trop Med Hyg. 1997; 91: 425-8.
4. Manosroi J, Chutipongvivate S, Auwanit W, Manosroi A: Early
diagnosis of scrub typhus in Thailand from clinical specimens by
nested polymerase chain reaction. Southeast Asian J Trop Med Public
Health. 2003 Dec; 34(4): 831-8.
Kerala is a state on the Malabar Coast of southwestern India. It can
be found on the map at
<http://en.wikipedia.org/wiki/Kerala>. - Mod.LL]