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New World Screwworm_ Mexico 11_08_01

CEI LogoNew World Screwworm, Mexico

Impact Worksheet, November 8, 2001

Summary:

New World screwworm ( Cochliomyia hominivorax) was confirmed in the state of Chiapas, Mexico on October 29, 2001. The location of the outbreak is close to the plant which produces sterile flies for use in the screwworm eradication program in Central America. In addition to control measures such as quarantine and surveillance, release of sterile flies has begun in the area around the outbreak zone. Mexico is a major world producer of cattle and equids. In 1997, the state of Chiapas had a bovine population of 2.9 million head, which accounted for almost 10% of the total Mexican bovine population. The US imports large numbers of cattle from Mexico, the majority of which are steers going to slaughter. Almost 99% of Mexican live cattle exports are cattle from the arid and semiarid regions of the country, which would exclude Chiapas. The US also imports significant numbers of equids from Mexico. The normal inspection procedure for livestock entering the US from Mexico is sufficient for the detection of screwworm, therefore APHIS has imposed no additional requirements at this point in time.

How extensive is the situation in the affected country and what was the country’s disease status prior to the outbreak?

New World screwworm ( Cochliomyia hominivorax) was detected in two locations in the State of Chiapas, Mexico on October 29, 2001 (indicated by triangles on map). A total of 18 cattle were infested as of November 6. Control measures include activities such as quarantines on the affected/high risk farms, animal movement controls, dipping of susceptible animals, and surveillance (including use of traps and sentinel sheep) in the outbreak and surrounding zones. Release of sterile flies has begun in the outbreak zone (6 districts) and perifocal zone (8 districts). The location of the outbreak is approximately 25 kilometers from the plant (indicated by black square with flag on map) that sterilizes screwworms used in the screwworm eradication program in Central America. DNA studies are being conducted to help determine if this outbreak was caused by escape of fertile material from the plant or an introduction from another country.

New World screwworms have been eradicated from the US, Mexico and much of Central America. Mexico was declared free of screwworm in 1991. Since that time, there have been multiple outbreaks, the most recent being in 1997 in Tamaulipas (northeastern Mexico). In 1996, there was an outbreak of screwworm in Chiapas due to escape of fertile material from the screwworm sterilization plant.

Screwworm Mexico Map

Source: OIE Disease Information Report, APHIS IS

What is the country’s production and trade in affected animals and animal products?

Mexico ranked second in the world (below China) in both horse and mule stocks in 2000 and 2001, accounting for approximately 11% of world horse stocks and 24% of mule stocks (Table 1). Mexico also ranked eighth in the world in cattle stocks in 2000 and 2001 with approximately 2% of world cattle stocks. In 1997, the state of Chiapas had a bovine population of 2.9 million head, which accounted for almost 10% of the total Mexican bovine population. Mexico ranked fourth in world cattle exports in 1999 with 10% of the world’s exports (Table 2).

Table 1: Mexico’s live animal stocks in 2000 and 2001

Product

2000

2001

Stocks

% World

Stocks

% World

Cattle

2.3

2.3

Goats

1.3

1.4

Horses

10.7

10.7

Mules

24.1

24.3

Pigs

1.6

1.6

Sheep

0.6

0.6

Source: United Nations FAO

Table 2: Mexico’s trade of live animals in 1999

Product

1999 Trade

Imports

Exports

Number of Head

% World

Number of Head

% World

Cattle

2.3

10.1

Goats

2.8

0

Horses

3.1

0.3

Mules

0

3.3

Pigs

1.3

<0.01

Sheep

2.5

0.01

Source: United Nations FAO , ERS Current Situation and Outlook of Beef Production in Mexico 1990-1998

What are the US imports of affected animals or animal products from the country?

The US imports large numbers of cattle from Mexico, the majority of which are steers going to slaughter (Table 3). Significant numbers of equids are also imported. Based on 1997 data, almost 99% of live cattle exports from Mexico were cattle from the arid and semiarid regions of the country, which would exclude the state of Chiapas. All livestock imported into the US from Mexico are required to enter via designated ports. At the port of entry, each animal is individually inspected for signs of disease. During this inspection, wounds that might harbor screwworm would be thoroughly examined. Because this normal procedure is sufficient for the detection of screwworm, APHIS has imposed no additional requirements on livestock entering the US from Mexico at this point in time.

Table 3: US Imports from Mexico in 200 and 2001

Product

2000

2001 (Jan - Aug)

$ Value
(million)

Quantity (number)

$ Value
(million)

Quantity (number)

Bovine - not purebred breeding (010290)

Bovine - purebred breeding (010210)

0.09

338

0.06

24

Horses, Asses, Mules, etc. (0101)

Sheep and Goats (0104)

Source: World Trade Atlas, ERS Current Situation and Outlook of Beef Production in Mexico 1990-1998

What is the level of passenger traffic arriving in the United States from the affected country?

It is estimated that 10.3 million visitors arrived in the US from Mexico in the year 2000. Of these, 1.7 million came by air. While it is possible for humans to be infested with screwworms, and thus be a risk of bringing the organism into the US, animal products these passengers might be carrying would not be of risk.
Source: Department of Commerce, Tourism Industries (Secretaria de Turismo, Mexico)

CEI’s plans for follow up:

At this time, CEI has no plans for further activity regarding New World screwworm in Mexico. If you seek more information or wish to comment on this worksheet, please reply to this message or contact Vicki Bridges (970-490-7822) or Ken Geter (970-490-7817) .



Additional Information