Remote Sensing-Based Modeling of Infectious Disease Transmission - Biosurveillance: Methods and Case Studies - page 58

In addition, Linthicum et al. (1999) examined RVF outbreaks in East Africa
from 1950 to 1998 and observed that RVF outbreaks to be closely related to
anomalies in the Pacific and Indian Oceans' sea surface temperatures and
vegetation index data.
3.2.5 Filariasis
Lymphatic filariasis is a parasitic disease caused by three nematode species:
Wuchereria bancrofti, Brugia malayi, and Brugia timori . Wuchereria bancrofti is
the most common species, estimated to cause approximately 100 million
infections annually. Lymphatic filariasis is one of the neglected tropical dis-
eases designated by the WHO.
If not properly treated, filariasis infection may lead to elephantitis.
Although the case mortality is low, the social stigma carried by the disease is
significant. Fortunately, antihelminthic treatments for filariasis are effective
and cost-effective. Mass treatment with just one dose each of two drugs may
stop the transmission (The Carter Center 2009). Hence, the WHO considers
lymphatic filariasis to be an eradicable disease.
Humans are the definitive hosts for the parasites responsible for lymphatic
filariasis. Quite a few mosquito species, including those belonging to Aedes,
Anopheles, Culex, Mansonia, and Ochlerotatus , may serve as the intermedi-
ate hosts. The broad spectrum of mosquito species involved in filariasis
transmission makes targeted larval control challenging. On the other hand,
malaria bed nets can provide general protection for filariasis if the particu-
lar filariasis vector species are among those that feed during the night.
The same remote sensing parameters—precipitation, temperature, vegeta-
tion, humidity, and elevation—as in malaria can be used for assessment of
filariasis risks (Sabesab et al . 2006).
3.2.6 leishmaniasis
Leishmaniasis is a disease caused by the Leishmania parasites and transmit-
ted by phlebotomine sand flies. Leishmaniasis has two forms: cutaneous and
visceral. The latter is more serious, with a nearly 100% rate of mortality if left
untreated. Most leishmaniases are zoonotic, and natural reservoirs of the dis-
ease include domestic or wild animals, such as dogs and rodents. After being
bitten by infected female sand flies, humans may not necessarily become
infected except for those who are immunodepressed. Today, coinfection of
leishmaniasis and HIV has emerged as a significant problem. AIDS greatly
increases the risk of visceral leishmaniasis infection, and visceral leishma-
niasis infection accelerates the onset of AIDS. Among intravenous drug
users, sharing needles can also lead to direct human-to-human transmission
of leishmaniasis. Plowing and compacting soil to destroy rodent habitats or
removing the vegetation on which vector rodents feed can help reduce the
rodent reservoir and number of associated cases of cutaneous leishmaniasis.